Note: Descriptions are shown in the official language in which they were submitted.
CA 02812971 2013-04-15
MICRO-OPTIC SECURITY AND IMAGE PRESENTATION SYSTEM
Field of the Invention
The present invention relates to a synthetic magnification micro-optic system
that
in an exemplary embodiment is formed as a polymer film. The unusual optical
effects
provided by the various embodiments of the disclosure can be used as a
security device
for overt and covert authentication of currency, documents, and products as
well as visual
enhancement of products, packaging, printed material, and consumer goods.
Background
Various optical materials have been employed to provide authentication of
currency and documents, to identify and distinguish authentic products from
counterfeit
products, and to provide visual enhancement of manufactured articles and
packaging.
Examples include holographic displays, and other image systems involving
lenticular
structures and arrays of spherical micro-lenses. Holographic displays have
become
prevalent for use with credit cards, drivers' licenses, and clothing tags.
An example of a lenticular structure for document security is disclosed in
U.S. Patent
4,892,336 to Kaule, et al. directed to a security thread for embedding within
a
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document to provide anti-falsification measures. The security thread is
transparent
having a printed pattern on one side, on the opposite side, a lenticular lens
structure
coordinated with the printed pattern. The lenticular lens structure is
described as
comprised of a plurality of parallel cylinder lenses, or alternatively
spherical or
honeycomb lenses.
U.S. Patent 5,712,731 to Drinkwater, et at. discloses a security device that
includes an array of micro-images coupled with an array of substantially
spherical
micro-lenses. The lenses may also be astigmatic lenses_ The lenses are each
typically
50-250 um and with a focal length of typically 20012m.
These approaches all suffer from similar drawbacks. They result in a
relatively thick structure that is not particularly suitable for use with
document
authentication. Their use of cylindrical or spherical lenses provides a narrow
field of
view resulting in fuzzy images and requiring exact and difficult alignment of
the focal
point of the lenses with the associated images. Additionally, they have not
proven
particularly effective as security or anti-counterfeiting measures.
In view of these and other deficiencies, a need exists in the industry for
secure
and visually unique optical materials that can facilitate overt authentication
of
currency, documents, manufactured articles, and products and for optical
materials
that provide visual enhancement of manufactured articles, products, and
packaging.
Summary
The present disclosure relates to a film material that utilizes a regular two-
dimensional array of non-cylindrical lenses to enlarge micro-images, called
icons
herein, and to form a synthetically magnified image through the united
performance
of a multiplicity of individual lens/icon image systems. The synthetically
magnified
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images and the background surrounding them can be either colorless or colored,
and
either or both the images and the background surrounding them can be
transparent,
translucent, pigmented, fluorescent, phosphorescent, display optically
variable color,
metallized, or substantially retroreflective. The material displaying colored
images on
a transparent or tinted background is particularly well suited for use in
combination
with underlying printed information. When a piece of such material is applied
over
printed information both the printed information and the images are seen at
the same
time in spatial or dynamic motion relationship to each other. Material of this
kind
can also be overprinted, i.e. have print applied to the uppermost (lens)
surface of the
Material. Alternatively, the material displaying colored images (of any color,
including white and black) on a translucent or substantially opaque background
of
different color is particularly well suited for stand-alone use or with
overprinted
information, not in combination with underlying printed information.
The magnitude of the synthetic magnification achieved can be controlled by
the selection of a number of factors, including the degree of 'skew' between
the axes
of symmetry of the lens array and the axes. of symmetry of the icon array.
Regular
periodic arrays possess axes of symmetry that define lines that the pattern
could be
reflected around without changing the basic geometry of the pattern, that in
the ideal
of arrays are infinite in extent. A square array, for example, can be
reflected around
any diagonal of any square without changing the relative orientation of the
array: if
the sides of the squares are aligned with the x and y axes of the plane, then
the sides
of the squares will still be aligned with those axes after reflection, with
the
assumption that all sides are identical and indistinguishable.
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Instead of mirroring the square array the array can be rotated through an
angle
equal to the angle between the axes of symmetry of the same type. In the case
of a .
square array the array can be rotated through an angle of 90 degrees, the
angle
between diagonals, to arrive at an array orientation which is
indistinguishable from
the original array. Similarly, an array of regular hexagons can be mirrored or
rotated
about a number of axes of symmetry, including the "diagonals" of the hexagon
(the
lines connecting opposite vertices) or "midpoint divisors" (lines that connect
between
the center points of faces on opposite sides of the hexagon). The angle
between the
axes of symmetry of either type is sixty degrees (601 results in an array
orientation
that is indistinguishable from the original orientation.
If a lens array and an icon array are initially arranged with their planar
dimensions defining their respective x-y plane, one of the axes of symmetry
being
chosen to represent the x axis of the first array, the corresponding type of
axis of
symmetry (for example, diagonal axis of symmetry) being chosen to represent
the x
axis of the second array, with the two arrays separated by a substantially
uniform
distance in the z axis direction, then the arrays are said to have zero skew
if the x axes
of the arrays appear to be parallel to each other when the arrays are viewed
along the
z axis direction. In the case of hexagonal arrays, rotation of one array
through an
angle of 60 degrees, or multiples thereof, puts the arrays in alignment again,
so there
is no skew, just as there is no skew for a rotation of 90 degrees, or
multiples thereof,
in the case of square arrays. Any angular misalignment between the x axes that
is
different from these "zero skew rotations" is called the skew. A small skew,
such as
0.06 degree, can create a large magnification, in excess of 1,000x, and a
large skew,
such as 20 degrees produces a small magnification, potentially as small as lx.
Other
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factors, such as the relative scales of the two arrays and the F# of the lens,
can affect
both the magnification of the synthetic image as well as its rotation,
orthoparallactic
movement, and apparent visual depth.
There are a number of distinct visual effects that can be provided by the
present material (subsequently referred to as "Unison" for the material in
general, or
by the names "Unison Motion", "Unison Deep", "Unison SuperDeep", "Unison
Float", "Unison SuperFloat", "Unison Levitate", "Unison Morph", and "Unison 3-
D"
for Unison material presenting those respective effects), and their various
embodiments producing each of these effects, generally described as follows:
Unison Motion presents images that show orthoparallactic movement (OPM)
¨ when the material is tilted the images move in a direction of tilt that
appears to be
perpendicular to the direction anticipated by normal parallax. Unison Deep and
SuperDeep present images that appear to rest on a spatial plane that is
visually deeper
than the thickness of the material. Unison Float and SuperFloat present images
that
appear to rest on a spatial plane that is a distance above the surface of the
material;
=
and Unison Levitate presents images that oscillate from Unison Deep (or
SuperDeep)
to Unison Float (or SuperFloat) as the material is rotated through a given
angle (e.g.
90 degrees), then returning to Unison Deep (or SuperDeep) again as the
material is
further rotated by the same amount. Unison Morph presents synthetic images
that
change form, shape, or size as the material is rotated or viewed from
different
viewpoints. Unison 3-D presents images that show large scale three-dimensional
structure, such as an image of a face.
Multiple Unison effects can be combined in one film, such as a film that
incorporates multiple Unison Motion image planes that can be different in
form,
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color, movement direction, and magnification. Another film can combine a
Unison
Deep image plane and a Unison Float image plane, while yet another film can be
designed to combine Unison Deep, Unison Motion, and Unison Float layers, in
the
same color or in different colors, those images having the same or different
graphical
elements. The color, graphical design, optical effect, magnification, and
other visual
elements of multiple image planes are largely independent; with few
exceptions,
planes of these visual elements can be combined in arbitrary ways.
For many currency, document and product security applications it is desirable
that the total thickness of the film be less than 50 microns, (also referred
to herein as
" ", or "urn"), for example less than about 45 microns, and as a further
example in the .
range of about 10 microns to about 40-microns. This can be accomplished, for
example, through the use of focusing elements having an effective base
diameter of
less than 50 microns, as a further example less than 30 microns, and as yet a
further
example, from about 10 microns to about 30 microns. As another example, a
focusing element having a focal length of less than about 40 microns, and as a
further
example having a focal length of about 10 to less than about 30 microns, can
be used.
In a particular example focusing elements having a base diameter of 35 microns
and a
focal length of 30 microns can be used. An alternate, hybrid
refractive/diffractive
embodiment, can be made as thin as 8 microns.
The films herein are highly counterfeit resistant because of their complex
multi-layer structure and their high aspect-ratio elements that are not
amenable to
reproduction by commonly available manufacturing systems.
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Thus, the present system provides a micro-optic system preferably in the form
of a polymer film having a thickness that when viewed by unaided eye(s) in
reflective
or transmitted light projects one or more images that:
i. show orthoparallactic movement (Unison Motion);
ii. appear to lie on a spatial plane deeper than the thickness of the
polymer film (Unison Deep and Unison SuperDeep);
iii. appear to lie on a spatial plane. above a surface of the polymer
film (Unison Float and Unison SuperFloat);
iv. oscillate between a spatial plane deeper than the thickness of
the polymer film and a spatial plane above a surface of the film as the film
is
azimuthally rotated (Unison Levitate);
v. transform from one form, shape, size, color (or some
combination of these properties) into a different form, shape, size, or color
(or some
combination of these properties) (Unison Morph); and/or
vi. appear to have realistic three-dimensionality (Unison 3-D).
The present disclosure more particularly provides a synthetic magnification
micro-optic system and method of making the same comprising:
(a) one or more optical spacers;
(b) a micro image comprised of a periodic planar array of a plurality of image
icons having an axis of symmetry about at least one of its planar axes, and
positioned
on or next to the optical spacer; and
(c) a periodic planar array of image icon focusing elements having an axis of
symmetry about at least one of its planar axes, the axis of symmetry being the
same
planar axis as that of the micro image planar array, each focusing element
being either
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a polygonal base multi-zonal focusing element, a lens providing an enlarged
field of
view over the width of the associated image icon so that the peripheral edges
of the
associated image icon do not drop out of view, or an aspheric focusing element
having an effective diameter of less than 50 microns.
The system can include one or more of the aforementioned effects. A method
is provided by which said effects can be selectively included within the
system.
The present disclosure further provides a security device suitable for at
least
partial incorporation in or on, and for use on or in association with, a
security
document, label, tear tape, tamper indicating device, sealing device, or other
authentication or security device, which comprises at least one micro-optic
system, as
defined above. More particularly the present disclosure provides a document
security
device and method of making the same comprising:
(a) one or more optical spacers;
(b) a micro image comprised of a periodic planar array of a plurality of image
icons having an axis of symmetry about at least one of its planar axes, and
positioned
on or next to the optical spacer; and
(c) a periodic planar array of image icon focusing elements having an axis of
symmetry about at least one of its planar axes, the axis of symmetry being the
same
planar axis as that of the micro image planar array, each focusing element
being either
a polygonal base multi-zonal focusing element, a lens providing an enlarged
field of
view over the width of the associated image icon so that the peripheral edges
of the
associated image icon do not drop out of view, or an aspheric focusing element
having an effective diameter of less than 50 microns.
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CA 02812971 2014-12-02
Additionally, the present disclosure provides a visual enhancement device
which
comprises at least one micro-optic system, as defined above and having the
above
described effects, for visual enhancement of clothing, skin products,
documents, printed
matter, manufactured goods, packaging, point of purchase displays,
publications,
advertising devices, sporting goods, financial documents and transaction
cards, and all
other goods.
Also provided is a security document or label having at least one security
device,
as defined above, at least partially embedded therein and/or mounted thereon.
In accordance with another aspect of the present invention, there is provided
film
material utilizing a regular two dimensional array of non-cylindrical lenses
to enlarge
micro-images, and to form a synthetically magnified image through the united
performance of a multiplicity of individual lens/icon image systems, wherein
the lenses
have a diameter of less than 50 microns.
In accordance with another aspect of the present invention, there is provided
film
material utilizing a regular two dimensional array of non-cylindrical lenses
to enlarge
micro-images, and to form a synthetically magnified image through the united
performance of a multiplicity of individual lens/icon image systems, wherein
the micro-
images are formed from the voids in a microstructure.
Other features and advantages of the present disclosure will be apparent to
one of
ordinary skill from the following detailed description and accompanying
drawings.
Other systems, devices, methods, features, and advantage will be or become
apparent to one with skill in the art upon examination of the following
drawings and
detailed description. It is intended that all such additional systems,
methods, features, and
advantages be included within this description, be within the scope of the
present
disclosure, and be protected by the accompanying claims.
Brief Description of the Figures:
Many aspects of the disclosure can be better understood with reference to the
drawings. The components in the drawings are not necessarily to scale,
emphasis
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instead being placed upon clearly illustrating the principles of the present
disclosure.
Moreover, in the drawings, like reference numerals designate corresponding
parts
throughout the several views.
Fig. l a is a cross-section of a micro-optic system exemplifying one
embodiment of the present disclosure providing orthoparallactic movement of
the
images of the system.
Fig. lb is an isometric cutaway view of the embodiment of Fig. la.
Fig. 2a illustrates an orthoparallactic synthetic image motion effect of the
embodiment of Figs. la-b.
Figs. 2 b-c illustrate the visual effects of the Deep and Float embodiments of
the present system.
Figs. 2 d-f illustrate the visual effects obtained by rotation of a Levitate
embodiment of the present system.
Figs. 3 a-i are plan views showing various embodiments and fill-factors of
different patterns of symmetric two dimensional arrays of lenses of the
present
system.
Fig. 4 is a graph illustrating different combinations of Deep, Unison, Float,
and Levitate embodiment effects produced by variation of the icon element
period/lens period ratio.
. Figs. 5 a-c are plan views illustrating how the synthetic magnification
of the
icon images can be controlled by the relative angle between the lens array and
icon
array axes of the present system.
Figs. 6 a-c are plan views illustrating an embodiment accomplishing a
motphing effect of synthetically magnified images of the present system.
CA 02812971 2013-04-15
Figs. 7 a-c are cross-sections showing various embodiments of the icon layer
of the present system.
Figs. 8 a-b are plan views illustrating both 'positive' and 'negative' icon
element embodiments.
Fig. 9 is a cross-section view illustrating an embodiment of a multi-level
material for creating regions of a synthetically magnified image having
different
properties.
Fig. 10 is a cross-section view illustrating another embodiment of a multi-
level
material for creating regions of a synthetically magnified image having
different
properties.
Figs. 11 a-b are cross-section views showing reflective optics and pinhole
optics embodiments of the present system.
= Figs. 12 a-b are cross-section views comparing the structures of an all-
refractive material embodiment with a hybrid refractive/reflective material
embodiment.
Fig. 13 is a cross-section view showing a 'peel-to-reveal' tamper-indicating
material embodiment_
Fig. 14 is a cross-section view illustrating a 'peel-to-change' tamper-
indicating
material embodiment.
Figs. 15 a-d are cross-section views showing various embodiments of two-
sided systems.
Figs. 16 a-f are cross-section views and corresponding plan views illustrating
three different methods for creating grayscale or tonal icon element patterns
and
subsequent synthetically magnified images by the present system.
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Figs. 17 a-d are cross-section views showing the use of the present system in
conjunction with printed information.
Figs. 18 a-f are cross-section views illustrating the application of the
Present
system to, or incorporation into, various substrates and in combination with
printed
information.
Figs. 19 a-b are cross-section views comparing the in-focus field of view of a
spherical lens with that of a flat field aspheric lens when each are
incorporated into
the present system.
Figs. 20 a-c are cross-section views illustrating two benefits of utility
which
result from the use of a thick icon layer in the present system. .
Fig. 21 is a plan view that shows the application of the present system to
currency as a "windowed" security thread.
= . Fig. 22 illustrates the orthoparallactic motion embodiment of the
present
system of images in connection with a "windowed" security thread.
Fig. 23 illustrates half-toning a synthetic image of the present system.
Fig. 24a illustrates use of the present system to create combined synthetic
images that are smaller in dimension than the smallest feature of the
individual
= synthetic images.
Fig. 24b illustrates use of the present system to create narrow patterns of
gaps
between icon image elements.
Fig. 25 illustrates incorporation of covert, hidden information into icon
images
of the present system.
Fig. 26 illustrates creating fully three-dimensional images with the present
system.
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Fig. 27 illustrates the method for designing icon images for the three-
dimensional embodiment of Fig. 26.
Fig. 28 illustrates the icon image resulting from the method of Fig. 27.
Fig. 29 illustrates how the method of Fig. 27 can be applied to a complex
three-dimensional synthetic image.
Fig. 30 illustrates the central zone focal properties of an exemplary
hexagonal
base multi-zonal lens having an effective diameter of 28 microns.
Fig. 31 illustrates the central zone focal properties of a spherical lens
having a
diameter of 28 microns.
Fig. 32 illustrates the performance of the side zones of the hexagonal lens of
Fig. 30.
Fig. 33 illustrates the performance of the outer zones of the spherical lens
of
Fig. 31.
Detailed Description of the Embodiments
Reference is now made in detail to the description of the embodiments as
illustrated in the figures. While several embodiments are described in
connection
with these figures, there is no intent to limit the invention to the
embodiment or
embodiments disclosed herein. On the contrary, the intent is to cover all
alternatives,
modifications, and equivalents.
Fig. la illustrates one embodiment of the present micro-optic system 12
providing orthoparallactic movement of the images of the system.
The system 12 micro-lenses 1 that have at least two substantially equal axes
of
symmetry and that are arranged in a two-dimensional periodic array. Lens
diameter 2
is preferably less than 50p. and the interstitial space between lenses 3 is
preferably 511
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or less. (We use the terms "p,." and "p.m" interchangeably to mean the same
measurement). Micro-lens 1 focuses an image of icon element 4 and projects
this -
image 10 toward a viewer. The system is commonly used in situations having
normal
levels of ambient lighting, so the illumination of the icon images arises from
reflected
or transmitted ambient light. Icon element 4 is one element of a periodic
array of icon
elements having periods and dimensions substantially similar to those of the
lens
array including lens 1. Between the lens 1 and the icon element 4 is an
optical spacer
5, which may be contiguous with the lens 1 material or may optionally be a
separate
substrate 8 ¨ in this embodiment the lenses 9 are separate from the substrate.
The
icon elements 4 may be optionally protected by a sealing layer 6, preferably
of a
polymer material. Sealing layer 6 may be transparent, translucent, tinted,
pigmented,
opaque, metallic, magnetic, optically variable, or any combination of these
that
provide desirable optical effects and/or additional functionality for security
and
authentication purposes, including support of automated currency
authentication,
verification, tracking, counting and detection systems, that rely on optical
effects,
electrical conductivity or electrical capacitance, magnetic field detection.
The total thickness 7 of the system is typically less than 5011; the actual
thickness depends on the F# of the lenses 1 and the diameter of the lenses 2,
and the
thickness of additional security feature or visual effect layers. The repeat
period 11 of
the icon elements 4 is substantially identical to the repeat period of the
lenses 1; the
"scale ratio", the ratio of the repeat period of the icons to the repeat
period of the
lenses, is used to create many different visual effects. Axially symmetric
values of
the scale ratio substantially equal to 1.0000 result in Unison Motion
orthoparallactic
=
effects when the symmetry axes of the lenses and the icons are misaligned,
axially
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symmetric values of the scale ratio less than 1.0000 result in Unison Deep and
Unison
SuperDeep effects when the symmetry axes of the lenses and the icons are
substantially aligned, and axially symmetric values of the scale ratio greater
than
1.0000 result in Unison Float and Unison SuperFloat effects when the symmetry
axes
of the lenses and the icons are substantially aligned. Axially asymmetric
values of the
scale ratio, such as 0.995 in the X direction and 1.005 in the Y direction,
result in
Unison Levitate effects.
Unison Morph effects can be obtained by scale distortions of either or both
the
lens repeat period and the icon repeat period, or by incorporating spatially
varying
information into the icon pattern. Unison 3-D effects are also created by
incorporating spatially varying information into the icon pattern, but in this
embodiment the information represents different viewpoints of a three
dimensional
object as seen from specific locations substantially corresponding to the
locations of
the icons.
Fig. lb presents an isometric view of the present system, as depicted in cross-
section in Fig. la, having square array patterns of lenses 1 and icons 4 of
repeat period
11 and optical spacer thickness 5 (Fig. la is not specific to a square array
pattern, but
is a representative cross-section of all regular periodic array patterns). The
icon
elements 4 are shown as "$" images, clearly seen in the cut-away section at
the front.
While there is substantially a one-to-one correspondence between lenses 1 and
icon
elements 4, the axes of symmetry of the lens array will not, in general, be
exactly
aligned with the axes of symmetry of the icon array.
In the case of the Unison (orthoparallactic motion) material embodiment of
Figs. la-b with a scale ratio of 1.0000, when the lens 1 axes and icon
elements 4 axes
CA 02812971 2013-04-15
are substantially aligned, the resulting synthetic images of the icon elements
(in this
example, a giant "$") "blow-up" and are magnified by a factor that
theoretically
approaches infinity. Slight angular misalignment of the lens 1 axes and icon
elements
4 axes reduces the magnification factor of the synthetic images of the icon
elements
and causes the magnified synthetic images to rotate.
The synthetic magnification factor of Unison Deep, Unison Float, and Unison
Levitate embodiments depends on the angular alignment of the lens 1 axes and
the
icon elements 4 axes as well as the scale ratio of the system. When the scale
ratio is
not equal to 1.0000 the maximum magnification obtained from substantial
alignment
of these axes is equal to the absolute value of 1/(1.0000 ¨(scale ratio)).
Thus a
Unison Deep material having a scale ratio of 0.995 would exhibit a maximum
magnification of11/(1.000 ¨ 0.995)1= 200x. Similarly, a Unison Float material
having a scale ratio of 1.005 would also exhibit a maximum magnification of
11/(1.000 ¨ 1.005)1= 200x. In a manner similar to the Unison Motion material
embodiment, slight angular misalignment of the lens 1 axes and icon elements 4
axes
of the Unison Deep, Unison Float, and Unison Levitate embodiments reduces the
magnification factor of the synthetic images of the icon elements and causes
the
magnified synthetic images to rotate.
The synthetic image produced by a Unison Deep or SuperDeep icon pattern is
upright with respect to the orientation of the Unison Deep or SuperDeep icon
pattern,
while the synthetic image produced by a Unison Float or SuperFloat icon
pattern is
upside down, rotated one hundred and eighty degrees (180 ) with respect to the
Orientation of the Unison Float or Super Float icon pattern.
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Fig. 2a schematically depicts the counter-intuitive orthoparallactic image
motion effects seen in the Unison Motion embodiment. The left side of Fig. 2a
depicts a piece of Unison Motion material 12 in plan view being oscillated 18
about
horizontal axis 16. If the synthetically magnified image 14 moved according to
parallax, it would appear to be displaced up and down (as shown in Fig. 2a) as
the
material 12 was oscillated around the horizontal axis 16. Such apparent
parallactic
motion would be typical of real objects, conventional print, and holographic
images.
Instead of exhibiting parallactic motion, synthetically magnified image 14
shows
orthoparallactic motion 20¨ motion which is perpendicular to the normally
expected
parallactic motion direction. The right side of Fig. 2a depicts a perspective
view of a
piece of material 12 exhibiting the orthoparallactic motion of a single
synthetically
magnified image 14 as it is oscillated 18 about horizontal rotational axis 16.
The
dotted outline 22 shows the position of the synthetically magnified image 14
after it
has moved to the right by orthoparallaxis and the dotted outline 24 shows the
position
of the synthetically magnified image 14 after it has moved to the left by
orthoparallaxis.
The visual effects of the Unison Deep and Unison Float embodiments are
isometrically depicted in Figs. 2 b,c. In Fig. 2b,a piece of Unison Deep
material 26
presents synthetically magnified images 28 that stereoscopically appear to lie
beneath
the plane of the Unison Deep material 26 when viewed by the eyes of the
observer 30.
In Fig. 2c, a piece of Unison Float material 32 presents synthetically
magnified
images 34 that stereoscopically appear to lie above the plane of the Unison
Float
material 34 when viewed by the eyes of the observer 30. The Unison Deep and
Unison Float effects are visible from all azimuthal viewing positions and over
a wide
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range of elevation positions, from vertical elevation (such that the line of
sight from
the eyes of the observer 30 to the Unison Deep material 26 or Unison Float
material
32 is perpendicular to the surface of the materials) down to a shallow
elevation angle
which is typically less than 45 degrees. The visibility of the Unison Deep and
Unison
Float effects over a wide range of viewing angles and orientations provides a
simple
and convenient method of differentiating Unison Deep and Unison Float
materials
from simulations utilizing cylindrical lenticular optics or holography.
The Unison Levitate embodiment effect is illustrated in Figs. 2 d-f by
isometric views showing the stereoscopically perceived depth position of a
synthetically magnified image 38 in three different azimuthal rotations of the
Unison
Levitate material 36 and the corresponding plan view of the Unison Levitate
material
36 and synthetically magnified image 38 as seen by the eyes of the observer
30. Fig.
2d depicts the synthetically magnified image 38 (hereafter referred to as 'the
image')
as stereoscopically appearing to lie in a plane beneath the Unison Levitate
material 36
when said material is oriented as shown in the plan view. The heavy dark line
in the
plan view serves as an azimuthal orientation reference 37 for the sake of
explanation.
Note that in Fig. 2d the orientation reference 37 is aligned in a vertical
direction and
the image 38 is aligned in a horizontal direction. The image 38 appears in the
Unison
Deep position because the scale ratio is less than 1.000 along a first axis of
the Unison
Levitate material 36 that is aligned substantially parallel to a line
connecting the
pupils of the observer's two eyes (this will be hereafter called the
'stereoscopic scale
ratio'). The stereoscopic scale ratio of the Unison Levitate material 36 is
greater than
= 1.000 along a second axis perpendicular to this first axis, thereby
producing a Unison
Float effect of the image 38 when the second axis is aligned substantially
parallel to a
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line connecting the pupils of the observer's eyes, as shown in Fig. 2f. Note
that the
orientation reference 37 is in a horizontal position in this figure. Fig. 2e
depicts an
intermediate azimuthal orientation of the Unison Levitate material 36 that
produces a
Unison Motion orthoparallactic image effect because the stereoscopic scale
ratio in
this azimuthal orientation is substantially 1.000.
The visual effect of a Unison Levitate image 38 moving from beneath the
Unison Levitate material 36 (Fig. 2d) up to the level of the Unison Levitate
material
36 (Fig. 2e) and further up above the level of the Unison Levitate material 36
(Fig. 2f)
as the material is azimuthally rotated can be enhanced by combining the Unison
Levitate material 36 with conventionally printed information. The unchanging
stereoscopic depth of the conventional print serves as a reference plane to
better
perceive the stereoscopic depth movement of the images 38.
When a Unison material is illuminated by a strongly directional light source
such as a 'point' light source (ex: a spotlight or an LED flashlight) or a
collimated
source (ex: sunlight), "shadow images" of the icons may be seen. These shadow
images are unusual in many ways. While the synthetic image presented by Unison
does not move as the direction of illumination is moved, the shadow images
produced
do move. Furthermore, while the Unison synthetic images may lie in different
visual
planes than the plane of the material, the shadow images always lie in the
plane of the
material. The color of the shadow image is the color of the icon. So black
icons
create black shadow images, green icons create green shadow images, and white
icons .
create white shadow images.
The movement of the shadow image as the angle of illumination moves is tied
to the specific depth or motion Unison effect in a way that parallels the
visual effect
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present in the synthetic image. Thus the movement of a shadow image as the
angle of
the light is altered parallels the movement that the synthetic image shows
when the
angle of view is altered_ In particular:
Motion shadow images move orthoparallactically as the light source is moved.
Deep shadow images move in the same direction as the light source.
Float shadow images move opposite to the direction of the light source.
Levitate shadow images move in directions that are a combination of the
above:
Levitate Deep shadow images move in the same direction as the light
in the left-right direction, but opposite from the direction of the light in
the up-down direction; Levitate Float shadow images move opposite to
the light in the left right direction but in the same direction as the light
in the up-down direction; Levitate Motion shadow images show
orthoparallactic motion with respect to the light movement.
Unison Morph shadow images show morphing effects as the light source is
moved.
Additional unusual shadow image effects are seen when a diverging point
light source, such as an LED light, is moved toward and away from a Unison
film.
When the light source is further away its diverging rays more closely
approximate
collimated light, and the shadow images produced by Deep, SuperDeep, Float, or
SuperFloat Unison synthetic images appear approximately the same size as the
synthetic images. When the light is brought closer to the surface the shadow
images
of Deep and SuperDeep materials shrink because the illumination is strongly
divergent, while the shadow images of Float and SuperFloat materials expand.
=
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Illuminating these materials with converging illumination causes Deep and
= SuperDeep shadow images to enlarge to a size greater than the synthetic
images,
while Float and SuperFloat shadow images shrink
The shadow images of Unison motion material do not change scale
significantly as the convergence or divergence of illumination is changed,
rather, the
shadow images rotate about the center of illumination. Unison Levitate shadow
images shrink in one direction and enlarge in the perpendicular direction when
the
convergence or divergence of the illumination is changed. Unison Morph shadow
images change in ways specific to the particular Morph pattern as the
convergence or
divergence of the illumination is changed.
All of these shadow image effects can be used as additional authentication
methods for Unison materials utilized for security, anti-counterfeiting, brand
protection applications, and other similar applications.
Figs. 3 a-i are plan views showing various embodiments and fill-factors of
different patterns of symmetric two-dimensional arrays of micro-lenses.
Figs.3a, d
and g depict micro-lenses 46, 52, and 60, respectively, that are arranged in
regular
hexagonal array pattern 40. (The dashed array pattern lines 40,42, and 44
indicate the
symmetry of the pattern of lenses but do not necessarily represent any
physical
element of the lens array.) The lenses of Fig. 3a have substantially circular
base
geometry 46, the lenses of Fig.3g have substantially hexagonal base geometries
60,
and the lenses of Fig. 3d have intermediate base geometries which are rounded-
off
hexagons 52. A similar progression of lens geometries applies to the square
array 42
of lenses 48,54, and 62, wherein these lenses have base geometries which range
from
= substantially circular 48, to rounded-off square 54, to substantially
square 62, as seen
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in Figs. 31, e, and h. Correspondingly, the equilateral triangular array 44
holds lenses
having base geometries that range from substantially circular 50, to rounded-
off
triangle 58, to substantially triangular 64, as seen in Figs. 3c, f and i.
The lens patterns of Figs. 3 a-i are representative of lenses that can be used
for the present system. The intersititial space between the lenses does not
directly
contribute to the synthetic magnification of the images. A material created
using one
of these lens patterns will also include an array of icon elements that is
arranged in the
same geometry and at approximately the same scale, allowing for differences in
scale
utilized to produce Unison Motion, Unison Deep, Unison Float, and Unison
Levitate
effects. If the interstitial space is large, such as is shown in Fig. 3c, the
lenses are said
to have a low fill-factor and the contrast between the image and the
background will
be reduced by light scattered from icon elements. If the interstitial spaces
are small
the lenses are said to have a high fill-factor and the contrast between the
image and
the background will be high, providing the lenses themselves have good focal
properties and icon elements are in the lenses' focal planes. It is generally
easier to
form high optical quality micro-lenses with a circular or nearly circular base
than with
a square or triangular base. A good balance of lens performance and minimizing
of
interstitial space is shown in Fig. 3d; a hexagonal array of lenses having
base
geometries that are rounded hexagons.
Lenses having a low F# are particularly suitable for use in the present
system.
By low F# we mean less than 4, and in particular for Unison Motion
approximately 2
or lower. Low F# lenses have high curvature and a correspondingly large sag,
or
center thickness, as a proportion of their diameter. A typical Unison lens,
with an F#
of 0.8, has a hexagonal base 28 microns wide and a center thickness of 10.9
microns.
22
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A typical Drinkwater lens, with a diameter of 50 microns and a focal length of
200
microns, has an F# of 4 and a center thickness of 3.1 microns. If scaled to
the same
base size, the Unison lens has a sag almost six times larger than the
Drinlcwater lens.
We have discovered that polygonal base multi-zonal lenses, for example
hexagonal base multi-zonal lenses, have important and unexpected advantages
over
circular base spherical lenses. As explained above, hexagonal base multi-zonal
lenses
significantly improve manufacturability by virtue of their stress-relieving
geometry,
but there are additional unexpected optical benefits obtained through the use
of
hexagonal base multi-zonal lenses.
We refer to these lenses as multi-zonal because they possess three optical
zones that each provide a different and unique benefit to the subject
invention. The
three zones are the central zone (constituting approximately half of the area
of the
lens), the side zones, and the corner zones. These polygonal lenses have an
effective
diameter that is the diameter of a circle drawn inside the comer zones around
the=
central zone and including the side zones.
The central zone of the hexagonal base multi-zonal lens of the subject
invention has an aspheric form (for example, having the form defined by [
y--5.1316E)X4 ¨ (0.01679) X3 + (0.124931) X + 11.24824 for a 28 micron
diameter lens with a nominal 28 micron focal length) that brings light to a
focus at
least as well as a spherical surface having the same diameter and focal
length. Figure
illustrates the central zone 780 focal properties 782 of a nominal 28 micron
diameter hexagonal base multi-zonal lens 784 with a nominal 28 micron focal
length
in a polymer substrate 786 (lens and substrate n=1.51) and Figure 31
illustrates the
central zone 788 focal properties 790 of a 28 micron diameter spherical lens
792 with
23
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a nominal 30 micron focal length in a polymer substrate 794 (lens and
substrate
n=1.51). Comparison of these two figures clearly demonstrates that the
hexagonal
base multi-zonal lens 784 of the subject disclosure performs at least.as well
as the
spherical lens 792. The central zone 780 of the hexagonal base multi-zonal
lens 784
provides high image resolution and shallow depth of field from a wide variety
of
viewing angles.
=Each of the six side zones 796 of the hexagonal base multi-zonal lens 784 of
the subject invention have focal lengths that depend on the location with the
zone in a
complex way, but the effect is to cause the focus of the side zones 796 to be
spread
over a range of values 798 spanning approximately +1- 10 percent of the
central zone
focus, as illustrated in Figure 32. This vertical blurring 798 of the focal
point
effectively increases the depth of field of the lens in these zones 796, and
provides a
benefit that is equivalent to having a flat-field lens. The performance of the
outer
zones 800 of spherical lens 792 can be seen in Figure 33. The vertical
blurring of the
focal point 802 is significantly less for the spherical lens 792 than it is
for the
hexagonal base multi-zonal lens 784.
This is particularly important for off-normal viewing: the increased depth of
field, and effectively flatter field, mitigates the abrupt image defocus that
can occur
with a spherical lens when its curved focal surface separates from the icon
plane.
Consequently, a Unison material using hexagonal base multi-zonal lenses
displays
synthetic images that fade from focus more softly at higher viewing angles
than the
equivalent Unison material using spherical lenses. This is desirable because
it
increases the effective viewing angle of the material and therefore increases
its
usefulness as a security device or an image presentation device.
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The corner zones 806 of the hexagonal base multi-zonal lens 784 of Figure 32
possess diverging focal properties that provide the unexpected benefit of
scattering
808 ambient illumination onto the icon plane and thereby reducing the
sensitivity of
the Unison material to illumination conditions. The spherical lens 792 of
Figure 33
does not scatter the ambient illumination over as wide an area (as seen by the
absence
of rays scattered into the icon plane regions 804), so Unison materials made
using
spherical lenses have greater synthetic image brightness variations when
viewed from
a variety of angles than Unison materials made using hexagonal base multi-
zonal
lenses.
The benefit obtained from the exemplary hexagonal base multi-zonal lenses is
further magnified because hexagonal base multi-zonal lenses have a higher fill
factor
(ability to cover the plane) than spherical lenses. The interstitial space
between
spherical lenses provides virtually no scattering of ambient light, while this
non-
scattering area is much smaller in the case of hexagonal base multi-zonal
lenses.
Thus it is seen that even though the focal properties of a hexagonal base
multi-
zonal lens are inferior to those of a spherical lens as evaluated by
conventional optical
standards, in the context of the subject invention hexagonal base multi-zonal
lenses
provide unexpected benefits and advantages over spherical lenses.
Either type of lens can benefit from the addition of scattering
microstructures
or scattering materials introduced into, or incorporated into, the lens
interstitial spaces
to enhance the scattering of ambient illumination onto the icon plane.
Furthermore,
the lens interstitial spaces can be filled with a material that will form a
small radius
meniscus, with either converging or diverging focal properties, to direct
ambient
illumination onto the icon plane. These methods may be combined, for example,
by =
CA 02812971 2013-04-15
incorporating light scattering particles into a lens interstitial meniscus
fill material.
Alternatively, the lens interstitial zones can be originally manufactured with
suitably
scattering lens interstitial zones.
A spherical lens having these proportions is very difficult to manufacture
because the high contact angle between the surface of the film and the edge of
the lens
acts as a stress concentrator for the forces applied to separate the lens from
the tool
during manufacture. These high stresses tend to cause the adhesion of the lens
to the
film to fail and to failure of removal of the lens from the tool. Furthermore,
the
'optical performance of a low F# spherical lens is progressively compromised
for
radial zones away from the center of the tens: low F# spherical lenses do not
focus
well except near their central zone.
. Hexagonal base lenses have an unexpected and significant benefit
over lenses
that have a more substantially circular base: hexagonal lenses release from
their tools
with lower peeling force than the optically equivalent lenses with
substantially
circular bases. Hexagonal lenses have a shape that blends from substantially
axially
symmetric near their center to hexagonally symmetric, with corners that act as
stress
concentrators, at their bases. The stress concentrations caused by the sharp
base
corners reduce the overall peeling force required to separate the lenses from
their
molds during manufacturing. The magnitude of this effect is substantial ¨ the
peeling
forces can be reduced during manufacturing by a factor of two or more for
hexagonal
base lenses as compared to substantially circular base lenses.
The image contrast of the material can be enhanced by filling the lens
interstitial spaces with a light absorbing (dark colored) opaque pigmented
material,
effectively forming a mask for the lenses. This eliminates the contrast
reduction that
A.
CA 02812971 2013-04-15
arises from light scattered from the icon layer through the lens interstitial
spaces. An
additional effect of this interstitial fill is that the overall image becomes
darker
because incoming ambient illumination is blocked from passing through the
interstitial spaces to the icon plane. The image clarity produced by lenses
having
aberrant focusing at their periphery can also be improved by an opaque
pigmented
interstitial fill, providing that this fill occludes the aberrant peripheral
lens zone.
A different effect can be obtained by filling the lens interstitial spaces
with a
white or light colored material, or a material color matched to a substrate to
be used
with the Unison material. If the light colored lens interstitial fill is dense
enough and
the icon plane incorporates a strong contrast between the icon elements and
the
background, the Unison synthetic image will be substantially invisible when
viewed
with reflected light, yet will be distinctly visible when viewed in
transmitted light
from the lens side, but not visible when viewed from the icon side. This
provides the
novel security effect of having a one-way transmission image that is visible
only in
transmitted light and visible only from one side.
Fluorescing materials can be utilized in a lens interstitial coating instead
of, or
in addition to, visible light pigments to provide additional means of
authentication.
Fig. 4 graphs the effects of changing the stereoscopic scale ratio, SSR (the
icon element repeat period/ the lens array repeat period), along an axis of
the present
material. Zones of the system having an SSR greater than 1.0000 will produce
Unison Float and SuperFloat effects, zones having an SSR of substantially
1.0000 will
produce Unison Motion orthoparallactic motion (OPM) effects, and zones having
an
SSR less than 1.0000 will produce Unison Deep and Unison SuperDeep effects.
All
of these effects can be produced and transitioned from one to another in a
variety of
CA 02812971 2013-04-15
ways along an axis of system film. This figure illustrates one of an infinite
variety of
such combinations. The dashed line 66 indicates the SSR value corresponding
substantially to 1.0000, the dividing line between Unison Deep and Unison
SuperDeep and Unison Float and Unison SuperFloat, and the SSR value which
demonstrates OPM. In zone 68 the SSR of the Unison material is 0.995, creating
a
Unison Deep effect.
Adjacent to this is zone 70 in which the SSR is ramped from 0.995 up to
1.005, producing a spatial transition from a Unison Deep to a Unison Float
effect.
The SSR in the next zone 72 is 1.005 creating a Unison Float effect. The next
zone
= 10 74 creates a smooth transition down from a Unison Float effect to a
Unison Deep
effeci Zone 76 proceeds stepwise up from a Unison Deep effect, to OPM, to a
Unison Float effect, and zone 78 steps it back down to OPM. The variations in
repeat
period needed to accomplish these effects are generally most easily
implemented in
the icon element layer. In addition to varying the SSR in each zone, it may be
desirable to vary the rotational angle of each zone of the arrays, preferably
within the
icon element array, to keep the synthetically magnified images substantially
similar in
size.
The easiest way to interpret this graph is to see it as a cross-section of the
stereoscopic depth that will be perceived across this axis of a piece of
system
material. It is therefore possible to create a stereoscopically sculpted field
of images,
a contoured visual surface, by local control of the SSR and optionally by
=
corresponding local control of the array rotational angle. This
stereoscopically
sculpted surface can be used to represent an unlimited range of shapes,
including
human faces. A pattern of icon elements that create the effect of a
stereoscopically
28
CA 02812971 2013-04-15
sculpted grid, or periodic dots, can be a particularly effective way to
visually display a
complex surface.
Figs. 5 a-c are plan views depicting the effect of rotating one array pattern
with respect to the other in the production of material of the present system.
Fig. 5a
shows a lens array 80 having a regular periodic array spacing 82, without
substantial
change in the angle of the array axes. Fig. 5b shows an icon element array 84
with a
progressively changing array axis orientation angle 86. If the lens array 80
is
combined with the icon element array 84 by translating the lens array over the
icon
array, as drawn, then the approximate visual effect that results is shown in
Fig. 5c. In
Fig.5c the material 88 created by combining lens array 80 and icon array 84
creates a
pattern of synthetically magnified images 89, 90, 91 that vary in scale and
rotation
across the material. Towards the upper edge of the material 88 image 89 is
large and
shows a small rotation. Image 90, toward the upper middle section of material
88 is
smaller and is rotated through a significant angle with respect to image 89.
The
different scales and rotations between images 89 and 91 are the result of the
differences in the angular misalignment of the lens pattern 82 and the icon
element
pattern 86.
Figs. 6 a-c illustrate a method for causing one synthetically magnified OPM
image 98 to morph into another synthetically magnified image 102 as the first
image
moves across a boundary 104 in the icon element patterns 92 and 94. Icon
element
pattern 92 bears circle-shaped icon elements 98, shown in the magnified inset
96.
Icon element pattern 94 bears star-shaped icon elements 102, shown in the
magnified
inset 100. Icon element patterns 92 and 94 are not separate objects, but are
joined at
their boundary 104. When the material is assembled using this combined pattern
of
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icon elements the resulting OPM images will show the morphing effects depicted
in
Figs. 6b and c: Fig. 6b shows OPM circle images 98 moving to the right 107
across
the boundary 104 and emerging from the boundary as star images 102 also moving
to
the right. Image 106 is in transition, part circle and part star, as it
crosses the
boundary. Fig. 6c of the figure shows the images after they have moved further
to the
right: image 98 is now closer to the boundary 104 and image 106 has almost
completely crossed the boundary to complete its morphing from circle to star.
The
morphing effect can be accomplished in a less abrupt marmer by creating a
transition
zone from one icon element pattern to the other, instead of having a hard
boundary
104. In the transition zone the icons would gradually change from circle to
star
through a series of stages. The smoothness of the visual morphing of the
resulting
OPM images will depend on the number of stages used for the transition. The
range
of graphical possibilities is endless. For example: the transition zone could
be
designed to make the circle appear to shrink while sharp star points protruded
up
through it, or alternatively the sides of the circle could appear to dent
inward to create
a stubby star that progressively became sharper until it reached its final
design.
Figs. 7 a-c are cross-sections of materials of the present system that
illustrate
alternative embodiments of the icon elements. Fig. 7a depicts a material
having
lenses I separated from icon elements 108 by optical spacer 5. Icon elements
108 are
formed by patterns of colorless, colored, tinted, or dyed material applied to
the lower
surface of optical spacer 5. Any of the multitude of common printing methods,
such
=
as ink jet, laserjet, letterpress, flexo, gravure, and intaglio, can be used
to deposit icon
elements 108 of this kind so long as the print resolution is fine enough.
CA 02812971 2013-04-15
Fig. 7b depicts a similar material system with a different embodiment of icon
elements 112. In this embodiment the icon elements are formed from pigments,
dyes,
or particles embedded in a supporting material 110. Examples of this
embodiment of
icon elements 112 in supporting material 110 include: silver particles in
gelatin, as a
photographic emulsion, pigmented or dyed ink absorbed into an ink receptor
coating,
dye sublimation transfer into a dye receptor coating, and photochromic or
thermochromic images in an imaging film.
Fig. 7c depicts a microstructure approach to forming icon elements 114. This
method has the benefit of almost unlimited spatial resolution. The icon
elements 114
can be formed from the voids in the microstructure 113 or the solid- regions
115,
singly or in combination. The voids 113 can optionally be filled or coated
with
another material such as evaporated metal, material having a different
refractive
index, or dyed or pigmented material.
Figs. 8 a,b depict positive and negative embodiments of icon elements. Fig.
8a shows positive icon elements 116 that are colored, dyed, or pigmented 120
against
a transparent background 118. Fig. 8b shows negative icon elements 122 that
are
transparent 118 against a colored, dyed, or pigmented background 120. A
material of
the present system may optionally incorporate both positive and negative icon
elements. This method of creating positive and negative icon elements is
particularly
well adapted to the microstructure icon elements 114 of Fig. 7c.
Fig. 9 shows a cross-section of one embodiment of a pixel-zone material of the
present system. This embodiment includes zones with lenses 124 having a short
focus
and other zones with lenses having a long focus 136. The short focus lenses
124
project images 123 of icon elements 129 in icon plane 128 disposed at the
focal plane
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of lenses 124. The long focus lenses 136 project images 134 of icon elements
137 in
icon plane 132 disposed at the focal plane of lenses 136. Optical separator
126
separates short focus lenses 124 from their associated icon plane 128. Long
focus
lenses 136 are separated from their associated icon plane 132 by the sum of
the
thicknesses of optical separator 126, icon plane 128, and second optical
separator 130.
Icon elements 137 in the second icon plane 132 are outside the depth of focus
of short
focus lenses 124 and therefore do not form distinct synthetically magnified
images in
the short focus lens zones. In a similar manner, icon elements 129 are too
close to
long focus lenses 136 to form distinct synthetically magnified images.
Accordingly,
zones of material bearing short focus lenses 124 will display images 123 of
the icon
elements 129, while zones of material bearing long focus lenses 136 will
display
images 134 of icon elements 137. The images 123 and 134 that are projected can
differ in design, color, OPM direction, synthetic magnification factor, and
effect,
including the Deep, Unison, Float, and Levitate effects described above.
Fig. 10 is a cross-section of an alternate embodiment of a pixel-zone material
of the present system. This embodiment includes zones with lenses 140 elevated
by a
lens support mesa 144 above the bases of the non-elevated lenses 148. The
focal
length of the elevated lenses 140 is the distance 158, placing the focus of
these lenses
in the first icon plane 152. The focal length of the non-elevated lenses 148
is the
distance 160, placing the focus of these lenses in the second icon plane 156.
These
two focal lengths, 158 and 160, may be chosen to be similar or dissimilar. The
elevated lenses 140 project images 138 of icon elements 162 in icon plane 152
disposed at the focal plane of lenses 140. The non-elevated lenses 148 project
images.
146 of icon elements 164 in icon plane 156 disposed at the focal plane of
lenses 148.
32
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The elevated lenses 140 are separated from their associated icon elements 162
by the
= sum of the thickness of the lens support mesa 144 and the optical
separation 150. The
non-elevated lenses 148 are separated from their associated icon elements 164
by the
sum of the thickness of the optical separation 150, the icon layer 152, and
the icon
separator 154. Icon elements 164 in the second icon plane 156 are outside the
depth
of focus of the elevated lenses 140 and therefore do not form distinct
synthetically
magnified images in the elevated lens zones. In a similar manner, icon
elements 152
are too close to non-elevated lenses 148 to form distinct synthetically
magnified
images. Accordingly, zones of material bearing elevated lenses 140 will
display
images 138 of the icon elements 162, while zones of material bearing non-
elevated
lenses 136 will display images 146 of icon elements 156. The images 138 and
146
that are projected can differ in design, color, OPM direction, synthetic
magnification
factor, and effect, including Deep, Unison, Float, and Levitate effects.
Figs. 11 a,b are cross-sections illustrating non-refractive embodiments of the
present system. Fig. lla illustrates an embodiment that utilizes a focusing
reflector
166 instead of a refractive lens to project images 174 of icon elements 172.
The icon
layer 170 lies between the viewer's eyes and the focusing optics. Focusing
reflectors
166 can be metallized 167 to obtain high focusing efficiency. The icon layer
170 is
maintained at a distance equal to the focal length of the reflectors by
optical separator
168. Fig. 1 lb discloses a pinhole optics embodiment of this material. Opaque
upper
layer 176, preferably black in color for contrast enhancement, is pierced by
apertures
178. Optical separator element 180 controls the field of view of the system.
Icon
elements 184 in icon layer 182 are imaged through apertures 178 in a manner
similar
to the pinhole optics of a pinhole camera. Because of the small amount of
light
33
CA 02812971 2013-04-15
passed through the apertures, this embodiment is most effective when it is
back-
illuminated, with light passing through the icon plane 182 first, then through
the
apertures 178. Effects of each of the above-described embodiments, OPM, Deep,
Float, and Levitate, can be created using either the reflective system design
or the
pinhole optics system design.
Figs. 12 a,b are cross-sections comparing the structures of an all-refractive
material 188 with a hybrid refractive/reflective material 199. Fig. 12a
depicts an
exemplary structure, with micro-lenses 192 separated from the icon plane 194
by
optical separator 198. Optional sealing layer 195 contributes to the total
refractive
system thickness 196. Lenses 192 project icon images 190 toward the viewer
(not
shown). Hybrid refractive/reflective material 199 includes micro-lenses 210
with
icon plane 208 directly beneath them. Optical spacer 200 separates the lenses
210 and
the icon plane 208 from reflective layer 202. Reflective layer 202 can be
metallized,
such as by evaporated or sputtered aluminum, gold, rhodium, chromium, osmium,
depleted uranium or silver, by chemically deposited silver, or by multi-layer
interference films. Light scattered from icon layer 208 reflects from
reflective layer
202, passes through icon layer 208 and into lenses 210 which project images
206
toward the viewer (not shown). Both of these figures are drawn to
approximately the
same scale: by visual comparison it can be seen that the total system
thickness 212 of
the hybrid refractive/reflective system 199 is about half the total system
thickness 196
of the all-refractive system 188. Exemplary dimensions for equivalent systems
are
29 total refractive system 188 thickness 196 and 17ji for total hybrid
refractive/reflective system 199 thickness 212. The thickness of a
refractive/reflective
system can be further reduced by scaling. Thus, a hybrid system having lenses
15p. in
34
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diameter can be made with a total thickness of about 81.L. Effects of each of
the above
described embodiments, OPM, Deep, Float, Levitate, Morph, and 3-D can be
created
using the hybrid refractive/diffractive design.
Fig. 13 is a cross-section showing a 'peel-to-reveal' tamper-indicating
material
embodiment of the present system. This embodiment does not display an image
until
it is tampered with. The untampered structure is shown in region 224, where a
refractive system 214 is optically buried under a top layer 216 consisting of
an
optional substrate 218 and a peelable layer 220 which is conformal to the
lenses 215.
Peelable layer 220 effectively forms negative lens structures 220 that fit
over positive
lenses 215 and negate their optical power. Lenses 215 cannot form images of
the icon
layer in the untampered region, and the light scattered 222 from the icon
plane is
unfocused. Top layer 216 may include an optional film substrate 218.
Tampering,
shown in region 226, causes the release of top layer 216 from the refractive
system
214, exposing the lenses 215 so that they can form images 228. Effects of each
of the
above described embodiments, OPM, Deep, Float, and Levitate, can be included
in a
tamper indicating 'peel-to-reveal' system of the type of Fig. 13.
Fig. 14 is a cross-section illustrating a 'peel-to-change' tamper-indicating
material embodiment of the present system. This embodiment displays a first
image
248 of a first icon plane 242 prior to tampering 252, then displays a second
image 258,
at region 254 after it has been tampered with. The untampered structure is
shown in
region 252, where two refractive systems, 232 and 230, are stacked. The first
icon
plane 242 is located beneath the lenses 240 of the second system. Prior to
tampering
in region 252 the first, or upper, system 232 presents images of the first
icon plane
242. The second icon plane 246 is too far outside the depth of focus of lenses
234 to
CA 02812971 2013-04-15
form distinct images. The first lenses 234 are separated from the second
lenses 240
by an optional substrate 236 and a peelable layer 238 which is conformal to
the
second lenses 240. Peetable layer 232 effectively forms negative lens
structures 238
that fit over positive lenses 240 and negate their optical power. Top layer
232 may
include optional film substrate 236. Tampering results in the peeling 256 of
the top
layer 232, shown in region 254, from the second refractive system 230,
exposing the
second lenses 240 so that they can form images 258 of the second icon layer
246.
Second lenses 240 do not form images of the first icon layer 242 because the
icon
Layer is too close to the lenses 240.
This embodiment of a tamper indicating material is well suited to application
as a tape or label applied to an article. Tampering releases the top layer
232, leaving
the second system 230 attached to the article. Prior to tampering, this
embodiment
presents a first image 248. After tampering 254 the second system 230, still
attached
to the article, presents a second image 258 while the peeled layer 256
presents no
image at all. Effects of each of the above described embodiments, OPM, Deep,
Float,
and Levitate, can be included in either the first system 232 or the second
system 230.
Note that an alternative embodiment accomplishing a similar effect to that of
Fig. 14 is to have two separate systems laminated to each other. In this
embodiment
when the upper layer is peeled it takes the first icon plane and its image(s)
with it,
revealing the second system and its image(s).
Figs. 15 a-d are cross-sections showing various two-sided embodiments of the
present system. Fig. 15a depicts a two-sided material 260 that includes a
single icon
plane 264 that is imaged 268 by lenses 262 on one side and imaged 270 by a
second
set of lenses 266 on the opposite side. The image 268 seen from the left side
(as
36
CA 02812971 2013-04-15
drawn) is the mirror image of the image 270 seen from the right side. Icon
plane 264
may contain icon elements that are symbols or images which appear similar in
mirror
image, or icon elements which appear different in mirror image, or
combinations of
icon elements wherein a portion of the icon elements are correct-reading when
viewed
from one side and the other icon elements are correct-reading when viewed from
the
other side. Effects of each of the above described embodiments, OPM, Deep,
Float,
and Levitate, can be displayed from either side of a two-sided material
according to
this embodiment.
Fig. 15b illustrates another two-sided embodiment 272 having two icon planes
276 and 278 that are imaged, 282 and 286 respectively, by two sets of lenses,
274 and
280 respectively. This embodiment is essentially two separate systems, 287 and
289,
such as illustrated in Fig. la, that have been joined together with an icon
layer spacer
277 in between them. The thickness of this icon layer spacer 277 will
determine the
degree that the 'wrong' icon layer is imaged 284 and 288 by a set of lenses.
For
example, if the thickness of icon layer spacer 277 is zero, such that icon
layers 276
and 278 are in contact, then both icon layers will be imaged by both sets of
lenses 274
and 280. In another example, if the thickness of icon layer spacer 277 is
substantially
larger than the depth of focus of lenses 274 and 280, then the 'wrong' icon
layers will
not be imaged by the lenses 274 and 280. In yet another example, if the depth
of
focus of one set of lenses 274 is large, but the depth of focus of the other
set of lenses
is small (because the lenses 274 and 280 have different RN, then both icon
planes
276 and 278 will be imaged 282 through lenses 274 but only one icon plane 278
will
be imaged through lenses 280, so a material of this type would show two images
from
one side but only one of those images, mirrored, from the opposite side.
Effects of
37
CA 02812971 2013-04-15
each of the above described embodiments, OPM, Deep, Float, and Levitate, can
be
displayed from either side of a two-sided material according to this
embodiment, and
the projected images 282 and 286 can be of the same or different colors.
Fig. 15c shows yet another two-sided material 290 having a pigmented icon
layer spacer 298 that blocks the lenses on one side of the material from
seeing the
'wrong' set of icons. Lenses 292 image 294 icon layer 296 but cannot image
icon
layer 300 because of the presence of pigmented icon layer 298. Similarly,
lenses 302
image 304 icon layer 300, but cannot image icon layer 296 because of the
presence of
pigmented icon layer 298. Effects of each of the above described embodiments,
OPM, Deep, Float, and Levitate, can be displayed from either side of a two-
sided
material according to this embodiment, and the projected images 294 and 304
can be
of the same or different colors.
Fig. 15d discloses a further two-sided material 306 embodiment having lenses
308 that image 318 icon layer 314 and lenses 316 on the opposite side that
image 322
icon layer 310. Icon layer 310 is close to, or substantially in contact with,
the bases of
lenses 308 and icon layer 314 is close to, or substantially in contact with,
the bases of
lenses 316. Icons 310 are too close to lenses 308 to form an image, so their
light
scatters 320 instead of focusing. Icons 314 are too close to lenses 316 to
form an
image, so their light scatters 324 instead of focusing. Effects of each of the
above
described embodiments, OPM, Deep, Float, and Levitate, can be displayed from
either side of a two-sided material according to this embodiment, and the
projected
images 318 and 322 can be of the same or different colors.
Figs. 16 a-f are cross-sections and corresponding plan views illustrating
three
different methods for creating grayscale or tonal icon element patterns and
subsequent
38
CA 02812971 2013-04-15
synthetically magnified images with the present system. Figs. 16 a-c are cross-
section
= details of the icon side of a material 307, including part of optical
separator 309 and a
transparent micro structured icon layer 311. The icon elements are formed as
bas-
relief surfaces 313, 315, 317 that are then filled with a pigmented or dyed
material
323, 325, 327 respectively. The underside of the icon layer may be optionally
sealed
by a sealing layer 321 that can be transparent, tinted, colored, dyed, or
pigmented, or
opaque. The bas-relief micro structures of icon elements 313, 315, and 317
provide
thickness variations in the dyed or pigmented fill material, 323, 325, and 327
respectively, that create variations in the optical density of the icon
element as seen in
plan view. The plan views corresponding to icon elements 323, 325, and 327 are
plan
views 337, 339, and 341. The use of this method to create grayscale or tonal
synthetically magnified images is not limited to the specifics of the examples
disclosed here, but may be generally applied to create an unlimited variety of
grayscale images.
Fig. 16 a includes icon element 313, dyed or pigmented icon element fill 323,
and corresponding plan view 337. The cross section view of the icon plane at
the top
of this figure can only show one cutting plane through the icon elements. The
location of the cutting plane is indicated by the dashed line 319 through the
plane
views 337, 339, and 341. Accordingly, the cross-section of icon element 313 is
one
plane through a substantially hemispherical-shaped icon element. By suitably
limiting the overall dye or pigment density of the fill 323, thickness
variations of the
dyed or pigmented fill 323 create a tonal, or grayscale, optical density
variations
represented in the plan view 337. An array of icon elements of this type can
be
39
CA 02812971 2013-04-15
synthetically magnified within the present material system to produce images
that
show equivalent grayscale variations.
Fig. 16 b includes icon element 315, dyed or pigmented icon element fill 325,
and corresponding plan view 339. Plan view 339 shows that the icon element 315
is a
bas-relief representation of a face. The tonal variations in an image of a
face are
complex, as shown by the complex thickness variations 325 in the cross-section
view.
As disclosed with regard to icon element 313, an array of icon elements of
this type,
as shown by 315, 325, and 339, can be synthetically magnified within the
present
material system to produce images that show equivalent grayscale variations
representing, in this example, the image of a face.
Fig. 16 c includes icon element 317, dyed or pigmented fill 327, and
corresponding plan view 341. In a manner similar to the discussion of Figs. 16
a,b,
above, the bas-relief shape of this icon element structure produces a tonal
variation in
the appearance of the dyed and pigmented fill 327 and in the synthetically
magnified
image produced by the present material system. Icon element 317 illustrates a
method
for creating a bright center in a rounded surface, as compared to the effect
of icon
element 313 which creates a dark center in a rounded surface.
Figs. 16 d,e disclose another embodiment 326 of transparent bas-relief micro
structured icon layer 311 including icon elements 329 and 331 that are coated
with a
high refractive index material 328. The icon layer 311 can be sealed with an
optional -
sealing layer 321 that fills the icon elements 329 and 331, 330 and 332,
respectively.
The high refractive index layer 328 enhances the visibility of sloping
surfaces by
creating reflections from them by total internal reflection. Plan views 342
and 344
present representative images of the appearance of icon elements 329 and 331
and
CA 02812971 2013-04-15
their synthetically magnified images. This high refractive index coating
embodiment
provides a kind of edge-enhancement effect without adding pigment or dye to
make
the icons and their images visible.
Fig. 16 f discloses yet another embodiment 333 of transparent bas-relief micro
structured icon 335 utilizing an air, gas, or liquid volume 336 to provide
visual
definition for this phase interface 334 microstructure. Optional sealing layer
340 may
be added with or without optional adhesive 338 to entrap the air, gas, or
liquid volume
336. The visual effect of a phase interface icon element is similar to that of
a high
refractive index coated icon element 329 and 331.
Figs. 17 a-d are cross-sections showing the use of the present system as a
laminating film in conjunction with printed information, such as may be
utilized in the
manufacture off.D. cards and driver's licenses, wherein the material 348
(consisting
of the coordinated micro-array of lenses and images described above) covers a
substantial proportion of the surface. Fig. I7a depicts an embodiment of
Unison used
as a laminate over print 347. Material 348 having at least some optical
transparency
in the icon layer is laminated to fibrous substrate 354, such as paper or
paper
substitute, with lamination adhesive 350, covering or partly covering print
element
352 that had previously been applied to the fibrous substrate 354. Because the
material 348 is at least partially transparent, the print element 352 can be
seen through
it and the effect of this combination is to provide the dynamic image effect
of the
present system in combination with the static print.
Fig. 17b shows an embodiment of the system material used as a laminate over
a print element 352 applied to a nonfibrous substrate 358, such as a polymer
film. As
in Fig 17a, material 348 having at least some optical transparency in the icon
layer is
41
CA 02812971 2013-04-15
laminated to nonfibrous substrate 358, such as polymer, metal, glass, or
ceramic
substitute, with lamination adhesive 350, covering or partly covering print
element
352 that had previously been applied to the nonfibrous substrate 354. Because
the
material 348 is at least partially transparent, the print element 352 can be
seen through
it and the effect of this combination is to provide the dynamic image effect
in
combination with the static print.
Fig. 17c depicts the use of a print element directly on the lens side of
material
360. In this embodiment material 348 has print element 352 directly applied to
the
upper lens surface. This embodiment does not require that the material be at
least
partly transparent: the print element 352 lies on top of the material and the
dynamic
image effects can be seen around the print element. In this embodiment the
material
348 is used as the substrate for the final product, such as currency, ID
cards, and other
articles requiring authentication or providing authentication to another
article.
Fig. 17d depicts the use of a print element directly on the icon side of an at-
least partially transparent material 362. Print element 352 is applied
directly to the
icon layer or sealing layer of an at-least partially transparent system
material 348.
Because the system material 348 is at least partially transparent, the print
element 352
can be seen through it and the effect of this combination is to provide the
dynamic
image effect in combination with the static print. In this embodiment the
system
material 348 is used as the substrate for the final product, such as currency,
ID cards,
and other articles requiring authentication or providing authentication to
another
article.
42
CA 02812971 2013-04-15
Each of the embodiments of Figs. 17 a-d can be used singly or in combination.
Thus, for example, a system material 348 can be both overprinted (Fig. 17c)
and
backside printed (Fig. I 7d), then optionally laminated over print on a
substrate
(Figs. 17 a,b). Combinations such as these can further increase the
counterfeiting,
simulation, and tampering resistance of the material of the present system.
Figs. 18 a-f are cross-sections illustrating the application of the present
system
to, or incorporation into, various substrates and in combination with printed
information. The embodiments of Figs. 18 a-f differ from those of Figs. 17 a-d
in that
the former figures disclose system material 348 that covers most or all of an
article,
whereas the present figures disclose embodiments wherein the system material
or its
optical effect do not substantially cover a whole surface, but rather cover
only a
portion of a surface. Fig. 18a depicts a piece of at-least partially
transparent system
material 364 adhered to a fibrous or non-fibrous substrate 368 with adhesive
element
366. Optional print element 370 has been directly applied to the upper, lens,
surface
of material 364. Print element 370 may be part of a larger pattern that
extends beyond
the piece of material 364. The piece of material 364 is optionally laminated
over print
element 372 that was applied to the fibrous or non-fibrous substrate prior to
the
application of the material 364.
Fig. 18b illustrates an embodiment of single-sided system material 364
incorporated into an non-optical substrate 378 as a window, wherein at least
some of
the edges of the system material 364 are captured, covered, or enclosed by the
non-
optical substrate 378. Print elements 380 may be optionally applied on top of
the
system material lens surface and these print elements may be aligned with, or
correspond to, print elements 382 applied to the non-optical substrate 378 in
the area
43 --
CA 02812971 2013-04-15
adjacent to print element 380. Similarly, print elements 384 can applied to
the
opposite side of the non-optical substrate aligned with, or corresponding to,
print
elements 386 applied to the icon or sealing layer 388 of the system material
364. The
effect of a window of this kind will be to present distinct images when the
material is
viewed from the lens side and no images when viewed from the icon side,
providing a
one-way image effect.
Fig. 18c shows a similar embodiment to that of Fig. 18b, except that the
system material 306 is double-sided material 306 (or other double-sided
embodiment
described above). Print elements 390, 392, 394, and 396 substantially
correspond in
function to print elements 380, 382, 384, 386, previously described. The
effect of a
material window of this kind will be to present different distinct images when
the
material is viewed from opposite sides. For example, a window incorporated
into a
currency paper could display the numerical denomination of the bill, such as
"10"
when viewed from the face side of the bill, but when viewed from the back side
of the
bill the Unison window could display different information, such as "USA",
that may
be in the same color as the first image or a different color.
Fig. 18d illustrates a transparent substrate 373 acting as the optical spacer
for a
material formed by a zone of lenses 374 of limited extent and an icon layer
376
extending substantially beyond the periphery of the zone of lenses 374. In
this
embodiment the present effects will only be visible in that zone that includes
both
lenses and icons (corresponding to lens zone 374 in this figure). Both the
lenses 374
and the adjacent substrate may optionally be printed 375, and print elements
may also
be applied to the icon layer 376 or to an optional sealing layer covering the
icons (not
indicated in this figure ¨ see Fig. 1). Multiple lens zones can be used on an
article
44
CA 02812971 2013-04-15
after the manner of this embodiment; wherever a lens zone is placed the Unison
effects will be seen; the size, rotation, stereoscopic depth position, and OPM
properties of the images can be different for each lens zone. This embodiment
is well
suited for application to ID cards, credit cards, drivers' licenses, and
similar
applications.
Fig. 18e shows an embodiment that is similar to that of Fig. 18d, except that
the icon plane 402 does not extend substantially beyond the extent of the lens
zone
= 400. Optical spacer 398 separates the lenses 400 from the icons 402.
Print elements
404 and 406 correspond to print elements 375 and 377 in Fig. 18d. Multiple
zones
400 can be used on an article after the manner of this embodiment; each zone
can
have separate effects. This embodiment is well suited for application to ID
cards,
credit cards, drivers' licenses, and similar applications.
Fig. 18f depicts an embodiment that is similar to Fig. 18d except that the
present embodiment incorporates optical spacer 408 that separates lenses 413
from
icon plane 410. Lenses 413 extend substantially beyond the periphery of the
icon
zone 412. Print elements 414 and 416 correspond to print elements 375 and 377
in
Fig. 18d. Multiple lens zones can be used on an article after the manner of
this
embodiment; wherever a lens zone is placed the present effects will be seen;
the size,
rotation, stereoscopic depth position, and OPM properties of the images can be
different for each lens zone. This embodiment is well suited for application
to ID
cards, credit cards, drivers' licenses, and similar applications.
Figs. 19 a,b illustrate cross-sectional views comparing the in-focus field of
view of a spherical lens with that of a flat field aspheric lens when each are
incorporated into a structure of the type described above. Fig. 19a
illustrates a
CA 02812971 2013-04-15
substantially spherical lens as applied in a system as described above.
Substantially
spherical lens 418 is separated from icon plane 422 by optical spacer 420.
Image 424
projected out perpendicular to the surface of the material originates at focal
point 426
within the icon layer 422. The image 424 is in sharp focus because the focal
point
426 is within the icon layer 422. When the lens is viewed from an oblique
angle, then
image 428 is blurry and out of focus because the corresponding focal point 430
is no
longer in the icon plane, but is above it a substantial distance. Arrow 432
shows the
field curvature of this lens, equivalent to the sweep of the focal point from
426 to 430.
The focal point is within the icon plane throughout the zone 434, then moves
outside
of the icon plane in zone 436. Lenses which are well suited to application in
coordination with a plane of printed images or icons typically have a low F#,
typically
less than 1, resulting in a very shallow depth of focus¨ higher F# lenses can
be used
effectively with Deep and Float effects, but cause proportionate vertical
binocular
disparity with effects described herein when used with Unison Motion effects.
As
soon as the lower limit of the depth of focus moves outside of the icon plane
the
image clarity degrades rapidly. From this figure it can be seen that the field
curvature
of a substantially spherical lens limits the field of view of the image: the
image is
distinct only within the in-focus zone 434, rapidly going out of focus for
more
oblique viewing angles. Substantially spherical lenses are not flat-field
lenses, and
the field curvature of these lenses is amplified for low F# lenses.
Fig. 19b illustrates an aspheric lens as applied to the present system. As an
aspheric lens, its curvature is not approximated by a sphere. Aspheric lens
438 is
separated from icon layer 442 by optical spacer 440. Aspheric lens 438
projects
image 444 of icon plane 442 normal to the plane of the material. The image
46
CA 02812971 2013-04-15
originates at focal point 446. The focal length of aspheric lens 438 lies
within the
= icon plane 442 for a wide range of viewing angles, from normal 444 to
oblique 448,
because it has a flat-field 452. The focal length of the lens varies according
to the
angle of view through it. The focal length is shortest for normal viewing 444
and
increases as the viewing angle becomes more oblique. At the oblique viewing
angle
448 the focal point 450 is still within the thickness of the icon plane, and
the oblique
image is therefore still in focus for this oblique viewing angle 448. The in-
focus zone
454 is much larger for the aspheric lens 438 than the in-focus zone 434 of the
substantially spherical lens 418. The aspheric lens 438 thus provides an
enlarged field
of view over the width of the associated image icon so that the peripheral
edges of the
associated image icon do not drop out of view compared to that of the
spherical lens
418. Aspheric lenses are preferred for the present system because of the
larger field
of view they provide and the resulting increase in visibility of the
associated images.
Figs. 20 a-c are cross-sections illustrating two benefits of utility which
result
from the use of a thick icon layer. These benefits apply whether the lens 456
used to
view them is substantially spherical 418 or aspheric 438, but the benefits are
greatest
in combination with aspheric lenses 438. Fig. 20a illustrates a thin icon
layer 460
system material including lenses 456 separated from icon layer 460 by optical
spacer
458. Icon elements 462 are thin 461 in comparison to the field curvature of
the lens
463, limiting the in-focus zone to a small angle, the angle between the image
projected in the normal direction 464 and the highest oblique angle image 468
that has
a focal point 470 within the icon layer 460. The greatest field of view is
obtained by
designing the normal image focus 466 to lie at the bottom of the icon plane,
thereby
maximizing the oblique field of view angle, limited by the point at which the
focal
47
CA 02812971 2013-04-15
point 470 lies at the top of the icon plane. The field of view of the system
in Fig. 20a
is limited to 30 degrees.
Fig. 20b illustrates the benefits obtained from the incorporation of an icon
plane 471 that is thick 472 in comparison to the field curvature of lens 456.
Lenses
456 are separated from thick icon elements 474 by optical spacer 458. Thick
icon
elements 474 remain in focus 475 over a larger field of view, 55 degrees, than
the thin
Icon elements 462 of Fig. 20a. The normal image 476 projected through lenses
456
from focal point 478 is in clear focus, and the focus remains clear while the
angle of
view increases all the way up to 55 degrees, where oblique image 480 focal
point 482
lies at the top.of the thick icon plane 471. The increased field if view is
greatest for a
flat-field lens, such as the aspheric lens 438 of Fig. 19b.
Fig. 20c illustrates yet another advantage of a thick icon plane 492; reducing
the sensitivity of the present system material to variations in thickness S
that may
result from manufacturing variations. Lens 484 is spaced a distance S from the
bottom surface of icon layer of thickness i. Lens 484 projects image 496 from
focal
point 498 disposed at the bottom of icon layer 492. This figure is drawn to
demonstrate that variations in the optical space S between the lenses and the
icon
layer can vary over a range equal to the thickness of the icon layer i without
loss of
image 496, 500, 504 focus. At lens 486 the optical spacer thickness is about
(S + 11
2) and the focal point 502 of image 500 is still within the thickness i of
icon layer
492. At lens 488 the thickness of the optical spacer has increased to (S + i )
490 and
the focal point 506 of image 504 lies at the top of thick icon element 494.
The optical
spacer thickness can therefore vary over a range corresponding to the
thickness of the
icon layer i : a thin icon layer therefore provides a small tolerance for
optical spacer
48
CA 02812971 2013-04-15
thickness variations and a thick icon layer provides a larger tolerance for
optical
spacer thickness variations.
An additional benefit is provided by a thick icon layer 492. Imperfect lenses,
such as substantially spherical lenses, may have a shorter focal length 493
towards
their edges than at their center 496. This is one aspect of the common
spherical
aberration defect of substantially spherical lenses. A thick icon layer
provides an icon
element that can be clearly focused over a range of focal lengths, 498 to 495,
thereby
improving the overall clarity and contrast of an image produced by a lens 484
having
focal length variations.
" Fig. 21 is a plan view that shows the application of the present system
to
currency and other security documents as a 'windowed' security thread. Fig. 21
shows a windowed thread structure including system material 508 that has been
slit
into a ribbon, referred to as a "thread", that is typically in the range of
0.5 mm to 10
mm in width. Thread 508 is incorporated into the fibrous document substrate
510 and
provides windowed zones 514. The thread 508 may optionally incorporate a
pigmented, dyed, filled, or coated sealing layer 516 to increase image
contrast and/or
to provide additional security and authentication features, such as electrical
conductivity, magnetic properties, nuclear magnetic resonance detection and
authentication, or to hide the material from view in reflected illumination
when
viewed from the back side of the substrate (the side opposite the side
presenting the
Unison synthetic images and an adhesive layer 517 to strengthen the bond
between
the thread 508 and the fibrous substrate 510. The thread 508 is maintained in
an
orientation to keep the lenses uppermost so that the image effects are visible
in the
windowed zones 514. Both the fibrous substrate 510 and the thread may be
49
CA 02812971 2013-04-15
overprinted by print elements 518 and the fibrous substrate may be printed 520
on its
opposite face.
Fig. 21 illustrates that thread 508 and its image effects 522 are only visible
from
the upper surface 521 of the substrate 510 in the windowed zones 514. Thread
508 is
covered by fibrous substrate material at the inside zones 512 and the image
effects 522
are not substantially visible in these zones. OPM effects are particularly
dramatic when
incorporated into thread 508. (See Fig. 22) As the fibrous substrate 510 is
tilted in various
directions the OPM image can be made to scan across the width 524 of the
thread,
producing a startling and dramatic visual effect. This scanning feature of an
OPM image
makes it possible to present image 522 which is larger than the width of the
thread 508.
The user examining the document containing a windowed thread 508 can then tilt
the
document to scan the whole image across the thread, scrolling it like a
marquee sign. The
effects of the Deep, Float, and Levitate embodiments can also be used to
advantage in a
windowed thread format.
The thread 508 may be at least partially incorporated in security papers
during
manufacture by techniques commonly employed in the paper-making industry. For
example, thread 508 may be pressed within wet papers while the fibers are
unconsolidated and pliable, as taught by U.S. Patent 4,534,398.
The windowed thread of the present system is particularly well suited for
application to currency. A typical total thickness for the thread material is
in the range of
22 to 3411, while the total thickness of currency paper may range as high as
88 . It is
possible to incorporate a windowed security thread of the present system into
currency
paper without substantially altering the total thickness of the paper by
CA 02812971 2013-04-15
locally reducing the thickness of the paper by an amount equivalent to the
thicknesS of
the thread.
In an exemplary embodiment, thread 508 comprises:
(a) one or more optical spacers;
(b) one or more optionally periodic planar arrays of micro-images
or icons positioned within, on, or next to an optical spacer; and
(c) one or more optionally periodic planar arrays of non-
cylindrical
micro lenses positioned on or next to either an optical spacer or a planar
icon array,
with each micro-lens having a base diameter of less than 50 microns.
In another embodiment, the micro-images or icons constitute filled voids or
recesses that are formed on a surface of the one or more optical spacers,
while the
non-cylindrical micro-lenses are aspheric micro-lenses, with each aspheric
micro-lens
having a base diameter ranging from about 15 to about 35 microns. At least one
pigmented sealing or obscuring layer 516 may be positioned on the planar
array(s) of
micro-images or icons for increasing contrast and thus visual acuity of the
icons and
also for masking the presence of thread 508 when the thread is at least
partially
embedded in a security document.
In yet another embodiment of the present invention, thread 508 comprises:
(a) an optical spacer having opposing upper and lower planar
surfaces;
(b) a periodic array of micro-images or icons comprising filled
recesses formed on the lower planar surface of the optical spacer,
(c) a periodic array of non-cylindrical, flat field, aspheric or
polygonal base multi-zonal micro-lenses positioned on the upper planar surface
of the
51
CA 02812971 2013-04-15
optical spacer, wherein each micro-lens have a base diameter ranging from
about 20
to about 30 microns; and
(d) a pigmented sealing or obscuring layer 516 positioned on
the
icon array.
The optical spacer(s) may be formed using one or more essentially colorless
polymers including, but not limited to, polyester, polypropylene,
polyethylene,
polyethylene terephthalate, polyvinylidene chloride, and the like. In an
exemplary
embodiment, the optical spacer(s) is formed using polyester or polyethylene
terephthalate and has a thickness ranging from about 8 to about 25 microns.
The icon and micro-lens arrays can be formed using substantially transparent .
or clear radiation curable material including, but not limited to acrylics,
polyesters,
epoxies, urethanes and the like. Preferably, the arrays are formed using
acrylated
urethane which is available from Lord Chemicals under the product designation
U107.
The icon recesses formed on the lower planar surface of the optical spacer
each measures from about 0.5 to about 8 microns in depth and typically 30
microns in
micro-image or icon width. The recesses can be filled with any suitable
material such
as pigmented resins, inks, dyes, metals, or magnetic materials. In an
exemplary
embodiment, the recesses are filled with a pigmented resin comprising a sub-
micron
pigment which is available from Sun Chemical Corporation under the product
designation Spectra Pac.
The pigmented sealing or obscuring layer 516 can be formed using one or
more of a variety of pacifying coatings or inks including, but not limited
to,
pigmented coatings comprising a pigment, such as titanium dioxide, dispersed
within
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a binder or carrier of curable polymeric material. Preferably, the sealing or
obscuring
layer 516 is formed using radiation curable polymers and has a thickness
ranging
from about 0.5 to about 3 microns.
Thread 508, which is described above, may be prepared in accordance with the
following method:
(a) applying a substantially transparent or clear radiation curable
resin to the upper and lower surfaces of the optical spacer;
(b) forming a micro-lens array on the upper surface and an icon
array in the form of recesses on the lower surface of the optical spacer;
(c) curing the substantially transparent or clear resin using a source
of radiation;
(d) filling the icon array recesses with a pigmented resin or ink;
(e) removing excess resin or ink from the lower surface of the
optical spacer; and
(0 applying a pigmented sealing or obscuring coating or layer to
the lower surface of the optical spacer.
In many cases, it is desirable that security threads used in currency and in
other high value financial and identification documents be detected and
authenticated
by high-speed non-contact sensors, such as capacitance sensors, magnetic field
sensors, optical transmission and opacity sensors, fluorescence, and/or
nuclear
magnetic resonance.
Incorporation of fluorescent materials into the lens, substrate, icon matrix,
or
icon fill elements of a Unison film can enable covert or forensic
authentication of the
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Unison material by observation of the presence and spectral characteristics of
the
fluorescence. A fluorescing Unison film can be designed to have its
fluorescent
properties visible from both sides of the material or from only one side of
the
material. Without an optical isolation layer in the material beneath the icon
layer, the
fluorescence of any part of a Unison material will be visible from either of
its sides.
Incorporation of an optical isolation layer makes it possible to separate the
visibility
of the fluorescence from its two sides. Thus a Unison material incorporating
an
optical isolation layer beneath the icon plane may be designed to exhibit
fluorescence
in a number of different ways: fluorescent color A visible from the lens side,
no
10. fluorescence visible from the optical isolation layer side, fluorescent
color A or B .
visible from the optical isolation layer side but not from the lens side, and
fluorescent
color A visible from the lens side and fluorescent color A or B visible from
the optical
isolation layer side. The uniqueness provided by the variety of fluorescent
signatures
possible can be used to further enhance the security of the Unison material.
The
optical isolation layer can be a layer of pigmented or dyed material, a layer
of metal,
or a combination of pigmented layers and metal layers, that absorbs or
reflects the
fluorescent emission from one side of the material and prevents it from being
seen
from the other side.
Icons formed from shaped voids and their inverse, icons formed from shaped
posts, are particularly enabling for adding machine-readable authentication
features to
a Unison material security thread for currency and other high value documents.
The
icon matrix, the icon fill, and any number of back coats (sealing coats) can
all,
separately and/or in all combinations, incorporate non-fluorescing pigments,
non-
fluorescing dyes, fluorescing pigments, fluorescing dyes, metal particles,
magnetic
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particles, nuclear magnetic resonance signature materials, lasing particles,
organic
LED materials, optically variable materials, evaporated metal, thin film
interference
materials, liquid crystal polymers, optical upconversion and downconversion
materials, dichroic materials, optically active materials (possessing optical
rotary
power), optically polarizing materials, and other allied materials.
In some circumstances, such as when a dark or colored coating (such as a
magnetic material or conductive layer) has been added to a Unison material or
when
the color of the icon plane is objectionable when seen through the back side
of a
substrate, it may be desirable to mask or hide the appearance of an embedded,
partially embedded, or windowed Unison material security thread from one side
of a
paper substrate as seen in reflected light, while the thread is visible from
the opposite
side of the substrate. Other types of currency security threads commonly
incorporate
a metal layer, typically aluminum, to reflect light that filters through the
surface
substrate, thereby providing similar brightness to the surrounding substrate.
Aluminum or other color neutral reflecting metal can be used in similar manner
to
mask the appearance of a Unison thread from the back side of a paper substrate
by
applying the metal layer on the back surface of the Unison material and then
optionally sealing it in place. A pigmented layer can be utilized for the same
purpose, that of hiding or obscuring the visibility of the security thread
from the
"back" side of the document, in place of a metallized layer, or in conjunction
with it.
The pigmented layer can be of any color, including white, but the most
effective color
is one that matches the color and intensity of the light internally scattered
within, and
outside of, the fibrous substrate.
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The addition of a metallized layer to a Unison material can be accomplished in
a number of ways, including direct metallization of the icon or sealing layer
of the
Unison material by evaporation, sputtering, chemical deposition, or other
suitable
means, or lamination of the icon or sealing layer of the Unison material to
the
metallized surface of a second polymer film. It is common practice to create
currency
security threads by metallizing a film, pattern demetallizirig this film to
leave narrow
'ribbons' of metallized area, laminating the metallized surface to a second
polymer
film, then slitting the laminated material such that the metal ribbons are
isolated from
the edges of the slit threads by the laminating adhesive; thereby protecting
the metal
from chemical attack at the edges of the thread. This method can also be
applied in
the case of the subject invention: the Unison material can simply replace the
second
laminating film. Thus a Unison material can be augmented by the addition of
patterned or unpatterned metallized layers.
Synthetic images can be designed as binary patterns, having one color (or
absence of color) defining the icons and a different color (or absence of
color)
defining the background; in this case each icon zone includes a complete
single-tone
image that utilizes image 'pixels' that are either full on or full off. More
sophisticated
synthetic images can be produced by providing tonal variations of the selected
icon
color. The synthetic image tonal variation can be created by controlling the
density of
the color in each icon image or by effectively 'half-toning' the synthetic
image by
including or excluding design elements in selected groups of icons.
The first method, controlling the density of the color in each icon image, may
=
be accomplished by controlling the optical density of the material creating
the
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microprinted icon image. One convenient method to do this utilizes the filled
void
icon embodiment, already described previously.
The second method, 'half-toning' the synthetic image by including or
excluding design elements in selected groups of icons, illustrated in Figure
23,
accomplished by including image design elements in a proportion of icon zones
that is
equal to the color density desired. Figure 23 illustrates this with an example
using a
hexagonal repeat pattern for the icon zones 570 that would be coordinated with
a
similar hexagonal repeat pattern of lenses. Each of the icon zones 570 do not
contain
identical information. All of the icon image elements, 572, 574, 576, and 578
are
present at substantially the same color density. Icon image elements 572 and
574 are
present in some of the icon zones and different icon image elements are
present in
other icon zones. Some icon zones contain the single icon image element 570.
Specifically, the icon image element 572 is present in half of the icon zones,
icon
image element 574 is present in three-fourths of the icon zones, icon image
element
578 is present in half of the icon zones, and icon image element 576 is
present in one-
third of the icon zones. The information present in each icon zone determines
whether its associated lens will show the color of the icon image pattern or
the color
of the icon image background from a particular viewing orientation. Either
image
elements 572 or 578 will be visible in all of the lenses associated with this
icon
pattern, but the synthetic image 580 space of icon image element 572 overlaps
the
synthetic image space of icon image element 578. This means that the overlap
zone
582 of the synthetic images of icons 572 and 578 will appear at 100% color
density,
because every lens will project icon image color in this zone.. The non-
overlapping
part of these two synthetic images, 588, is only visible in 50% of the lenses,
so it
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appears at 50% color density. The synthetic image 586 of icon element 576 is
visible
in only one third of the lenses, so it appears at 33.3...% density. The
synthetic image
584 of icon image element 576 correspondingly appears at 75% color density. It
is
clear within the scope of this teaching that a tremendous range of tonal
variations can
be obtained in the synthetic image through selective omission of icon image
elements
in selected percentages of icon zones. For greatest effectiveness the
distributions of
the icon image elements across the icon image zones should be relatively
uniform. =
A related icon image design method, illustrated in Figure 24a, can be used to
create
combined synthetic image elements that are smaller in dimension than the
smallest
feature of the individual synthetic image elements. This is possible in the
common
circumstance where the smallest feature size of an icon image is larger than
the
placement accuracy of the feature. Thus an icon image may have minimum
features
on the order of two microns in dimension, but those features may be placed
accurately
on any point on a grid of 0.25 micron spacing. In this case the smallest
feature of the
icon image is eight times larger than the placement accuracy of that feature.
As with
the previous diagram this method is illustrated using a hexagonal icon pattern
594, but
it applies equally well to any other usable pattern symmetry. In similar
fashion to the
method of Figure 23, this method relies on the use of different information in
at least
one icon zone. In the example of Figure 24a two different icon patterns, 596
and 598,
are each present in half of the icon zones (for clarity only one of each
pattern is shown
in this figure). These icon images produce a composite synthetic image 600
that
incorporates synthetic image 602 created by icon image elements 596, and
synthetic
image 604, created by icon image element 598. The two synthetic images, 602
and
604, are designed to have overlapped areas, 606 and 608,
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that appear to have 100% color density while the non-overlapped areas 605 have
50%
color density. The minimum dimension of the overlapped areas in the composite
= synthetic image may be as small as the synthetic magnification-scaled
positioning
accuracy of the icon image elements, and therefore may be smaller than the
minimum
feature size of the two constituent synthetic images that are designed to
overlap in a
small region. In the example of Figure 23, the overlap regions are used to
create the
characters for the number "10" with narrower lines than would otherwise be
possible.
This method can also be used to create narrow patterns of gaps between icon
image elements, as shown in Figure 24b. Hexagonal icon zones 609 could be
square
or any other suitable shape to make a space-filling array, but hexagonal is
preferred.
In this example, half the icon patterns the icon image 610, and half of them
are the
icon image 611. Ideally these two patterns would be relatively uniformly
distributed
among the icon zones. All of the elements of these patterns are depicted as
being of
substantially equal and uniform color density. In isolation these two patterns
do not
clearly suggest the form of the final image, and this can be used as a
security element
¨ the image is not obvious until it is formed by the overlying lens array. One
instance
of the synthetic image 612 formed by the combination of the synthetic image of
icon
elements 610 with the synthetic image of icon elements 611 is shown, whereby
the
- gaps that remain between the separate synthetic images form the numeral
"10". In
this case, two synthetic images are combined to form the final synthetic
image, so the
colored parts of this image 613 show 50% color density. This method is not
limited
by the details of this example: three icons could have been used instead of
two, the
gaps defining the desired element in the composite synthetic images can have
variable
widths and unlimited shape variety, and this method can be combined with
either the
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methods of Figures 23, 24a,b or 25, or an other icon image design method we
have
taught.
Covert, hidden information can be incorporated into the icon images that
cannot be seen in the resulting synthetic images. Having such covert
information
hidden in the icon images can be used, for example, for covert authentication
of an
object. Two methods for accomplishing this are illustrated by Figure 25. The
first
method is illustrated by the use of matched icon images 616 and 618. Icon
image 616
shows a solid border pattern and the number "42" contained inside of the
border. Icon
image 618 shows a solid shape with the number "42" as a graphical hole in that
shape.
In this example, the perimeter shapes of icon images 616 and 618 are
substantially
identical and their relative position within their respective icon zones, 634
and 636,
are also substantially identical. When a composite synthetic image 620 is
created
from these icon images, the border of the composite synthetic image 622 will
show
100% color density because all icon images have a pattern in that
corresponding area,
so there is full overlap in the synthetic images created from icon images 616
and 618.
The color density of the interior 624 of the composite synthetic image 620
will be
50%, since the image of the space surrounding the "42" comes from icon images
618
that only fill half the icon zones, and the image of the colored "42" comes
from icon
images 616 that also fill half the icon zones. Consequently, there is no tonal
differentiation between the "42" and its background, so the observed composite
=
synthetic image 626 will show an image having a 100% color density border 628
and
a 50% color density interior 630. The "42" covertly present in all of the icon
images
616 and 618 is thereby "neutralized" and will not be seen in the observed
composite
synthetic image 626.
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A second method for incorporating covert information into icon images is
= illustrated by triangles 632 in Figure 25. Triangles 632 may be randomly
placed
within the icon zones (not shown in this figure) or they can be placed in an
array or
other pattern that does not substantially match the period of the icon zones
634, 632.
Synthetic images are created from a multiplicity of regularly arrayed icon
images that
are imaged by a corresponding regular array of micro-lenses. Patterns in the
icon
plane that do not substantially correspond to the period of the micro-lens
array will
not form complete synthetic images. The pattern of triangles 632 therefore
will not
create a coherent synthetic imige and will not be visible in the observed
synthetic
image 626. This method is not limited to simple geometric designs, such as
triangles
632: other covert information, such as alpha-numeric information, bar codes,
data
bits, and large-scale patterns can be incorporated into the icon plane with
this method.
=
Figure 26 illustrates a general approach to creating fully three dimensional
integral images in a Unison material (Unison 3-D). A single icon zone 640
contains
icon image 642 that represents a scale-distorted view of an object to be
displayed in 3-
D as seen from the vantage point of that icon zone 640. In this case the icon
image
642 is designed to form a synthetic image 670 of a hollow cube 674. Icon image
642
has a foreground frame 644 that represents the nearest side 674 of hollow cube
672,
tapered gap patterns 646 that represent the corners 676 of the hollow cube
672, and a
background frame 648 that represents the farthest side 678 of the hollow cube
672. It
can be seen that the relative proportions of the foreground frame 644 and the
baCkground frame 648 in the icon image 642 do not correspond to the
proportions of
the nearest side 674 and the farthest side 678 of the synthetic image hollow
cube 672.
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The reason for the difference in scale is that images that are to appear
further from the
plane of the Unison material experience greater magnification, so their size
in the icon
image must be reduced in order to provide the correct scale upon magnification
to
form the synthetic image 672.
At a different location on the Unison 3-D material we find icon zone 650 that
includes a different icon image 652. As with icon image 642, icon image 652
represents a scale-distorted view of the synthetic image 672 as seen from the
different
vantage point of this icon zone 650. The relative scaling of foreground frame
654 and
background frame 658 are similar to the corresponding elements of icon image
642
(although this-will not be true, in general), but the position of the
background frame
658 has shifted, along with the size and orientation of the comer patterns
656. Icon
zone 660 is located a further distance away on the Unison 3-D material and it
presents
yet another scale-distorted icon image 662, including icon image 662 with
foreground
frame 664, tapered gap patterns 667, and background frame 668.
In general, the icon image in each icon zone in a Unison 3-D material will be
slightly different from its nearby neighbors and may be significantly
different from its
distant neighbors. -It can be seen that icon image 652 represents a
transitional stage
between icon images 642 and 662. In general, each icon image in a Unison 3-D
material may be unique, but each will represent a transitional stage between
the icon
images to either side of it.
Synthetic image 670 is formed from a multiplicity of icon images like icon
images 640, 650, and 660 as synthetically imaged through an associated lens
array.
The synthetic image of the hollow cube 674 shows the effects of the different
synthetic magnification factors that result from the effective repeat periods
of the
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different elements of each of the icon images. Let us assume that the hollow
cube
= image 674 is intended to be viewed as a SuperDeep image. In this case if
icon zone
640 was disposed some distance to the lower left of icon zone 650, and icon
zone 660
was disposed some distance to the upper right of icon zone 650, it can be seen
that the
effective period of the foreground frames 644, 654, and 664 will be less than
that of
the background frames 648, 658, and 668, thereby causing the closest face 676
of the
cube (corresponding to the foreground frames 644, 654, and 664) to lie closer
to the
plane of the Unison material and the farthest face 678 of the cube to lie
deeper and
further from the plane of the Unison material, and to be magnified by a
greater factor.
The corner elements 646, 656, and 667 coordinate with both the foreground and
background elements to create the effect of smoothly changing depth between
them.
The method of designing icon images for Unison 3-D is more fully described
in Figure 27. This figure isolates the method for a single image projector
680. As
previously described, a single image projector includes a lens, an optical
spacer, and
an icon image; the icon image having substantially the same dimensions as the
repeat
period of the lens (allowing for the small differences in scale that create
the Unison
visual effects). The field of view for the lens and its associated icon is
shown as the
cone 682: this also corresponds to an inversion of the focal cone of the lens,
so the
proportions of the field of view cone 682 are determined by the F# of the
lens.
Although the figure shows this cone as having a circular base, the base shape
will
actually be the same as the shape of an icon zone, such as a hexagon.
In this example we wish to create a Unison 3-D synthetic image that
incorporates three copies of the word "UNISON", 686, 690 and 694, at the same
visual size at three different SuperDeep image planes 684, 690, and 692. The
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diameter of the image planes 684, 688, and 692 expands with the field of view
cone:
in other words, as the depth of image increases, area covered by the field of
view cone
increases. Thus the field of view at the shallowest depth plane 684 only
encompasses
portions of "NIS" of the word UNISON, while the middle depth plane 688
encompasses all of "NIS" and portions of "U" and "0" and the deepest depth
plane
692 encompasses almost all of "UNISON", lacking only part of the final "N".
The information they presented (UNISONs 686, 690, and 694) by each of
these synthetic image planes 684, 688, and 692, must ultimately be
incorporated into a
single icon image in image projector 680. This is accomplished by capturing
the
information in the field of view cone 686 at each depth plane 684, 688, and
692, then
scaling the resulting icon image patterns to the same dimensions. Icon image
696
represents the field of view of UNISON image 686 as seen at depth plane 684,
icon
image 704 represents the field of view of UNISON image 690 as seen at depth
plane
688, and icon image 716 represents the field of view of UNISON image 694 as
seen
at depth plane 692.
Within icon image 696 icon image elements 698 originate from a portion of
the first "N" of UNISON image 686, icon image element 700 originates from a
portion of the of UNISON image 686, and icon image elements 702 originate
from portions of the "S" of UNISON image 686. Within icon image 704 icon image
element 706 originates from a portion of the "U" of UNISON image 690, icon
image
element 708 originates from the first "N" of UNISON image 690, icon image
element
710 originates from the "S" of UNISON image 690, and icon image element 714
originates from a portion of the "0" of UNISON image 690. Note that although
the
synthetic images 686, 690, and 694 are presented at similar scale, icon image
704 for
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the middle depth plane 688 presents its UNISON letters at a smaller scale than
those
of icon image 696. This accounts for the higher synthetic magnification that
icon
image 704 will experience (when synthetically combined with a multiplicity of
surrounding icon images for the same depth plane). In similar manner, icon
image
716 incorporates icon image elements 718 that originate from the UNISON image
694
and the UNISON letters incorporated in its icon image are at a further reduced
scale.
The final icon image for this image projector is created by combining these
three icon images 696, 704, and 716 into a single icon image 730, shown in
Figure 28.
The combined icon elements 732 incorporate all of the graphical and depth
information necessary for the image projector 680 to make its contribution to
the
synthetic image formed from a multiplicity of image projectors, each
incorporating
the specific icon image information that results from the intersection of its
own field
of view cone, centered on the image projector, with the levels and elements of
the
synthetic image to be produced. Since each image projector is displaced by at
least
one lens repeat period from every other image projector, each image projector
will
carry different information resulting from the intersection of its field of
view cone
with the synthetic image space.
Each of the icon images required to present a chosen 3-D image can be
computed from knowledge of the three-dimensional digital Model of the
synthetic
image, desired depth position and depth span to be presented in the synthetic
image,
the lens repeat period, the lens field of view, and the ultimate graphical
resolution of
the icon images. This latter factor puts an upper limit on the level of detail
that can be
presented at each depth plane. Since depth planes that lie further from the
plane of
the Unison material carry a larger amount of information (because of the
increased
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field of view) the graphical resolution limit of the icons has the greatest
impact on the
resolution of these synthetic image depth planes.
Figure 29 illustrates how the method of Figure 27 can be applied to a complex
three-dimensional synthetic image, such as an image of the priceless ice-age
carved
mammoth ivory artifact, the Lady of Brassempouy 742. Individual image
projector
738, incorporating at least a lens, an optical spacing element, and an icon
image (not
shown in this figure), lies in the plane 740 of a Unison material that
separate the float
synthetic image space from the deep synthetic image space. In this example the
synthetic image space spans the Unison material such that a portion of the
image lies
in the float synthetic image space and a portion lies in the deep synthetic
image space.
The image projector 738 has a substantially conical field of view that extends
both
into the deep synthetic image space 744 and into the float synthetic image
space 746.
A chosen number of deep image planes are selected, 748 and 752-762, at
whatever
spacing is required to obtain the deep synthetic image space resolution
desired.
Similarly, a chosen number of float image planes are selected, 750 and 764-
774, at
whatever spacing is required to obtain the float synthetic image space
resolution
desired. Some of these planes, such as deep planes 748 and float planes 750
will
extend beyond the synthetic image and will not contribute to the final
information in
the icon image. For clarity, the number of image planes shown in Figure 29 is
limited
to a small number but the actual number of image planes selected may be high,
such
as 50 or 100 planes, or more, to obtain the desired synthetic image depth
resolution.
The method of Figures 27 and 28 is then applied to obtain the icon image at
each depth plane by determining the shape of the intersection of the surface
of the
object 742 with the selected depth plane 756-774. The resulting separate icon
images
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are scaled to the final size of the combined icon image. All of the float icon
images
are first rotated 180 degrees (because they undergo that rotation again when
they are
projected, thereby returning them to their correct orientation in the
synthetic image)
then they are combined with the deep icon images to form the final icon image
for this
image projector 738. This process is repeated for each of the positions of the
image
projectors to obtain the complete pattern of icon images required to form the
full
synthetic image 742.
The resolution of the synthetic image depends on the resolution of the optical
projectors and the graphical resolution of the icon images. We have obtained
icon
image graphical resolutions, less than 0.1 micron, that exceed the theoretical
optical
resolution limit of magnifying optics ( 0.2 micron). A typical icon image is
created
with a resolution of 0.25 micron.
Unison materials can be manufactured by sheet or web processing utilizing
tools that separately incorporate the lens and icon microstructures. Both the
lens tools
and the icon tools are originated using photomasks and photoresist methods.
Lens tools are initially designed as semiconductor-type masks, typically black
chrome on glass. Masks having sufficient resolution can be created by
photoreduction, electron beam writing, or laser writing. A typical mask for a
lens tool
will incorporate a repeating pattern of opaque hexagons at a chosen period
such as 30
microns, with clear lines separating the hexagons that are less than 2 microns
wide.
This mask is then used to expose photoresist on a glass plate using a
conventional
semiconductor UV exposure system. The thickness of the resist is selected to
obtain
the desired sag of the lens. For example, a thickness of 5 microns of AZ 4620
positive photoresist is coated onto a glass plate by suitable means, such as
by spin
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coating, dip coating, meniscus coating, or spraying, to form lenses having a
nominal
30 micron repeat and a nominal 35 micron focal length. The photoresist is
exposed
with the mask pattern, and developed down to the glass in a conventional
manner,
then dried and degassed at 100 C for 30 minutes. The lenses are formed by
thermal
reflow according to standard methods that are known in the art. The resulting
photoresist micro-lenses are coated with a conductive metal, such as gold or
silver,
and a negative nickel tool is created by electroforming.
Icon tools are created in a similar manner. An icon pattern is typically
designed with the aid of CAD software and this design is transmitted to a
semiconductor mask manufacturer. This mask is used in similar manner to the
lens
mask, except the thickness Of the resist to be exposed is typically in the
range of 0.5
micron to 8 microns, depending on the optical density of the desired synthetic
image.
The photoresist is exposed with the mask pattern, developed down to glass in a
conventional manner, coated with a conductive metal, and a negative nickel
tool is
created by electroforming. According the choice of original mask design and in
the
choice of resist type used (positive or negative), the icons can be created in
the form
of voids in the resist pattern or they can be created in the form of "mesas"
or posts in
the resist pattern, or both.
Unison materials can be manufactured from a variety of materials and a
multiplicity of methods that are known in the art of micro-optic and
microstructure
replication, including extrusion embossing, radiation cured casting, soft
embossing,
and injection molding, reaction injection molding, and reaction casting. An
exemplary method of manufacture is to form the icons as voids in a radiation
cured
liquid polymer that is cast against a base film, such as 75 gage adhesion-
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PET film, then to form the lenses from radiation cured polymer on the opposite
face
of the base film in correct alignment or skew with respect to the icons, then
to fill the
icon voids with a subrnicron particle pigmented coloring material by gravure-
like
doctor blading against the film surface, solidify the fill by suitable means
(ex: solvent
removal, radiation curing, or chemical reaction), and finally apply an
optional sealing
layer that may be either clear, dyed, pigmented, or incorporate covert
security
materials.
The manufacture of Unison Motion material requires that the icon tool and the
lens tool incorporate a chosen degree of misalignment of the axes of symmetry
of the
two arrays. This misalignment of the icon and lens patterns axes of symmetry
controls the synthetic image size and synthetic image rotation in the produced
material. It is often desirable to provide the synthetic images substantially
aligned
with either the web direction or the cross-web direction, and in these cases
the total
angular misalignment of the icons and the lenses is divided equally between
the lens
pattern and the icon pattern. The degree of angular misalignment required is
usually
quite small. For example, a total angular misalignment on the order of 0.3
degree is
suitable to magnify 30 micron icon images to a size of 5.7 mm in a Unison
Motion
material. In this example, the total angular misalignment is divided equally
between
the two tools, so each tool is skewed through an angle of 0.15 degree in the
same
direction for both tools. The skew is in the same direction because the tools
form
microstructures on opposite faces of a base film, so the skews of the tools
add to each
other, instead of canceling each other.
Skew can be incorporated into the tools at the time of the original design of
the masks by rotating the whole pattern through the desired angle before
writing it.
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Skew can also be mechanically incorporated into a flat nickel tool by cutting
it at the
appropriate angle with a numerically controlled mill. The skewed tool is then
formed
into a cylindrical tool using the skew-cut edge to align the tool to the
rotational axis of
an impression cylinder.
The synthetic magnification micro-optic system herein can be combined with
additional features including but not limited to these embodiments as single
elements
or in various combinations, such as icon fill materials, back coatings, top
coatings,
both patterned and non-patterned, fill or inclusions in the lens, optical
spacer or icon
materials, as a laminate or coating. inks and or adhesives including aqueous,
solvent
or radiation curable, optically transparent, translucent or opaque, pigmented
or dyed
Indicia in the form of positive or negative material, coatings, or print
including but not
limited to inks, metals, fluorescent, or magnetic materials, X-ray, infrared,
or ultra-
violet absorbent or emitting materials, metals both magnetic and non-magnetic
including aluminum, nickel, chrome, silver, and gold; magnetic coatings and
particles
for detection or information storage; fluorescent dye and pigments as coatings
and
particles; ER fluorescent coatings, fill, dyes or particles; UV fluorescent
coatings, fill,
dyes or particles; phosphorescent dye and pigments as coatings and particles,
planchettes, DNA, RNA or other macro-molecule taggants, dichroic fibers,
radioisotopes, print receptive coatings, sizing, or primers, chemically
reactive
materials, micro-encapsulated ingredients, field affected materials,
conductive
particles and coatings both metallic and non-metallic, micro-perforated holes,
colored
threads or fibers, patches of Unison embedded in the surface of a document,
label, or
materials surface, bonded to paper or polymer as a carrier to adhere to paper
during
manufacture, fluorescent Dichrok threads or particles, raman scattering
coatings or
CA 02812971 2013-04-15
particles, color shifting coatings or particles, Unison laminated to paper,
paper board,
card board, plastic, ceramic, fabric, or metal substrate, Unison as a thread,
patch,
label, over wrap, hot stamp foil, or tear tape, holographic, diffractive,
diffractive
kinegram, isograms, photographic or refractive optical elements, liquid
crystal
materials, Up Conversion and Down Conversion materials.
The synthetic magnification micro-optic system herein has many fields of use
and applications. Examples include:
Government and defense applications ¨ whether Federal, State or Foreign
(such as Passports, II) Cards, Driver's Licenses, Visas, Birth Certificates,
Vital
Records, Voter Registration Cards, Voting Ballots, Social Security Cards,
Bonds,
Food Stamps, Postage Stamps, and Tax Stamps);
currency ¨ whether Federal, State or Foreign (such as security threads in
paper
currency, features in polymer currency, and features on paper currency);
documents (such as Titles, Deeds, Licenses, Diplomas, and Certificates);
financial and negotiable instruments (such as Certified Bank Checks,
Corporate Checks, Personal Checks, Bank Vouchers, Stock Certificates,
Travelers'
Cheeks, Money Orders, Credit cards, Debit cards, ATM cards, Affinity cards,
Prepaid
Phone cards, and Gift Cards);
confidential information (such as Movie Scripts, Legal Documents,
Intellectual Property, Medical Records/Hospital Records, Prescription
Forms/Pads,
and "Secret Recipes");
= product and brand protection, including Fabric & Home Care (such as
Laundry Detergents, fabric conditioners, dish care, household cleaners,
surface
coatings, fabric refreshers, bleach, and care for special fabrics);
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beauty care (such as Hair care, hair color, skin care & cleansing, cosmetics,
fragrances, antiperspirants & deodorants, feminine protection pads, tampons
and
pantiliners);
baby and family care (such as Baby diapers, baby and toddler wipes, baby
bibs, baby change 8c bed mats, paper towels, toilet tissue, and facial
tissue);
health care (such as Oral care, pet health and nutrition, prescription
pharmaceuticals, over-the counter pharmaceuticals, drug delivery and personal
health
care, prescription vitamins and sports and nutritional supplements;
prescription and
non-prescription eyewear; Medical devices and equipment sold to Hospitals,
Medical
Professionals, and Wholesale Medical Distributors (ie: bandages, equipment,
implantable devices, surgical supplies);
food and beverage packaging;
dry goods packaging;
electronic equipment, parts & vomponents;
apparel and footwear, including sportswear clothing, footwear, licensed and
non-licensed upscale, sports and luxury apparel items, fabric;
biotech pharmaceuticals;
aerospace components and parts;
automotive components and parts;
sporting goods;
tobacco Products;
software;
compact disks and DVD's;
explosives;
72-
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CA 02812971 2013-04-15
novelty items (such as gift wrap and ribbon)
books and magazines;
school products and office supplies;
business cards;
shipping documentation and packaging;
notebook covers;
book covers;
book marks;
event and transportation tickets;
gambling and gaming applications (such as Lottery tickets, game cards, casino
chips and items for use at or with casinos, raffle and sweepstakes);
home furnishing (such as towels, linens, and furniture);
flooring and wallcoverings;
jewelry & watches;
handbags;
art, collectibles and memorabilia;
toys;
displays (such as Point of Purchase and Merchandising displays);
product marking and labeling (such as labels, hangtags, tags, threads, tear
strips,
over-wraps, securing a tamperproof image applied to a branded product or
document
for authentication or enhancement, as camouflage, and as asset tracking.
Suitable materials for the embodiments described above include a wide range
of polymers. Acrylics, acrylated polyesters, acrylated urethanes,
polypropylenes, qarr'et
urethanes, and polyesters have suitable optical and mechanical properties for
both the
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CA 02812971 2013-04-15
microlenses and the microstructured icon elements. Suitable materials for the
optional substrate film include most of the commercially available polymer
films,
including acrylic, cellophane, Saran, nylon, polycarbonate, polyester,
polypropylene,
polyethylene, and polyvinyl. Microstructured icon fill materials can include
any of
the materials listed above as suitable for making microstructured icon
elements, as
well as solvent based inks and other commonly available pigment or dye
vehicles.
Dyes or pigments incorporated into these materials should be compatible with
the
chemical makeup of the vehicle. Pigments must have a particle size that is
substantially smaller than the smallest dimensions of any component of an icon
element. Optional sealing layer materials can include any of the materials
listed
above as suitable for making microstructured icon elements, plus many
different
commercially available paints, inks, overcoats, varnishes, laquers, and clear
coats
used in the printing and paper and film converting industries. There is no
preferred
combination of materials¨ the choice of materials depends o the details of the
material geometry, on the optical properties of the system, and on the optical
effect
that is desired.
Although exemplary embodiments have been shown and described, it will be
clear to those of ordinary skill in the art that a number of changes,
modifications, or
alterations to the invention as described can be made. All such changes,
modifications, and alterations should therefore be seen as within the scope of
the
disclosure.
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