Note: Descriptions are shown in the official language in which they were submitted.
CA 02642330 2008-08-13
Security element having an optically variable structure
[0001] This invention relates to a security element having an optically
variable
structure which has an embossed structure with linear embossed elements and a
coat-
ing, the embossed structure and the coating being so disposed that at least
parts of the
coating are completely visible upon perpendicular viewing but concealed upon
oblique viewing. The invention relates further to a method for producing such
a secu-
rity element, a data carrier having such a security element, and the use of
such a secu-
rity element or data carrier for product protection.
[0002] For protection against imitation, in particular with color copiers or
other re-
production methods, data carriers, such as bank notes, papers of value, credit
or iden-
tity cards, passports, certificates and the like, labels, packages or other
elements for
product protection are equipped with optically variable security elements. The
protec-
tion from forgery here is based on the fact that the optically variable
effect, which is
readily and clearly recognizable visually, is not rendered sufficiently or at
all by the
above-mentioned reproduction devices.
[0003] In this connection, CA 10 19 012 for example discloses a bank note
which
is provided in a partial area of its surface with a parallel printed line
pattern. For pro-
ducing the optically variable effect, a line structure is additionally
embossed into the
data carrier in the area of said printed line pattern, resulting in flanks
that are visible
only at certain viewing angles in each case. Targeted arrangement of the line
pattern
on flanks of like orientation causes the lines provided on the flanks to be
visible upon
oblique viewing of said flanks, while the line pattern is not recognizable
upon oblique
viewing of the back flanks. If phase jumps are provided in the line grid or in
the em-
bossed grid in partial areas of the embossed area, this permits information to
be repre-
sented that is recognizable either only from the first oblique viewing angle
or only
from the second viewing angle.
CA 02642330 2008-08-13
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100041 Although such an optically variable security element shows a compara-
tively sharp tilt effect to the viewer, the parallel printed line patterns
with constant
line spacing can nowadays be imitated with a certain effort by modern
reproduction
techniques. A further disadvantage is that the printed line patterns described
in CA 10
19 012 do not allow any tilt effects with highly detailed and elaborately
designed pic-
ture motifs as a coating.
[0005] The invention is therefore based on the problem of proposing a security
ele-
ment of the type stated at the outset that avoids the disadvantages of known
generic
security elements and offers an increased degree of falsification security.
Further-
more, a data carrier having such a security element and a method for producing
such a
security element are to be specified.
[0006] This problem is solved by the features of the independent claims.
Develop-
ments of the invention are the subject matter of the dependent claims.
[0007] The optically variable structure of the inventive security element
consists of
a coating which is formed substantially completely from nonlinear primitives,
and an
embossed structure superimposed on said coating. The embossed structure has
linear
embossed elements which are so combined with the coating comprising nonlinear
primitives that different infonnation is visible upon a change of viewing
direction.
The nonlinear primitives are characterized by the parameters of outline fonn,
size,
color and orientation, and so combined with the embossed structure that the
inventive
shadowing effect results. With respect to the linear embossed elements the
nonlinear
primitives are thus so disposed that certain inforlnation results for a viewer
in a top
view of the security element, said infonnation changing upon a change of
viewing
direction.
100081 A line will hereinafter be understood to be a connection of two points
ac-
cording to the definition stated in "Taschenbuch der Mathematik," Bronstein,
Se-
mendjajew, 25th edition. This definition of course includes not only a
straight con-
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nection but also a nonstraight, i.e. a curved, wavy or spiral, connection of
two points
in two- or three-dimensional space.
[0009] Applied to the present invention, this means that linear embossed
elements
are understood to be all three-dimensional elements whose projections into the
plane
of the optically variable element form a line according to the above
definition.
[0010] The linear embossed elements are characterized as a rule by four
flanks,
said flanks having dimensions that permit the inventive shadowing effect. That
is, the
flanks inust be so dimensioned that, for the viewer looking at such a flank,
informa-
tion located behind said flank is at least partly concealed or shadowed.
[0011] Nonlinear primitives will hereinafter be understood to be all elements
of
two- and three-dimensional space whose outline fonn is so selected that they
are not
linear elements according to the above definition of a line. The nonlinear
primitives
of the present application are therefore, in geometric terms, derived from a
single
two-dimensional point and not from a two-dimensional connection of two points
(line). The nonlinear primitives can thus generally be characterized as
compact,
nonelongate elements.
[0012] The use of nonlinear primitives of any outline fonn, size, color and
align-
ment makes it possible to give the coating of the optically variable structure
a design
so elaborate and highly detailed as to virtually rule out forgery at present.
The protec-
tion from forgery is also increased according to the invention by the fact
that substan-
tially the total coating is formed from nonlinear primitives. A potential
forger would
thus have to imitate not only single areas but the total coating with extreme
precision,
which is virtually impossible at present.
[0013] Besides the increase in falsification security by using the embossed
inven-
tive coating, there is advantageously also a considerable increase in possible
choices
with regard to the motifs and geometric patterns to be used for the coating,
as well as
the freedom of design for the motifs and patterns, thereby resulting in
considerably
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more impressive and optically more attractive tilt effects for the viewer upon
suitable
embossing of the coating. This makes the authenticity of an inventive security
ele-
ment easily ascertainable to the "man or woman on the street" as well. A
forged secu-
rity element can be readily recognized by the fact that the dramatic tilt
effect inherent
in the authentic optically variable structure can be observed only to a very
limited
extent or not at all for a very elaborately designed coating.
[0014) The use of the inventive nonlinear primitives advantageously also makes
it
possible to realize tilt effects hitherto unknown in connection with generic
security
elements, with picture motifs or geometric patterns represented in true
colors. Finally,
a further advantage of the invention is that the superiinposition of
primitives of dif-
ferent color permits secondary color effects dependent on viewing direction.
[00151 The inventive primitives are characterized firstly by the parameter of
out-
line form. All outline forms can be used that are nonlinear according to the
definition
stated hereinabove. Although the outline form of the primitives can be varied
within a
very wide range, those primitives are preferred that have a circular, oval or
poly-
gonally bounded outline form. A primitive is polygonally bounded according to
the
present invention if it is a polygon in the mathematical sense. Conceptually,
polygons
are determined in two- or three-dimensional space. Therefore, it is possible
to use
polygons starting with triangles up to polygons with a large number of sides.
Particu-
larly preferable polygons are various four-sided figures, such as
parallelograms,
squares, rectangles, rhombi and trapeziums. The nonlinear primitives can of
course
also have an outline form that is e.g. circular or oval in certain areas and
polygonally
bounded in other areas.
[0016] Besides said outline forms known from geometry, it is furthermore also
pre-
ferred that the linear primitives have an outline form determined by a symbol,
geo-
metric pattern and/or alphanumeric character. As symbols it is possible to use
all
nonlinear primitives that are accessible to the methods used for applying the
coating.
These may be for example mathematical symbols, such as the integral or root
symbol,
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or else the well-known sharp or double sharp symbol. Furthermore, it is
possible to
use characters, in particular alphanumeric characters, of all known fonts,
although
characters from the standard Latin and Greek fonts are particularly
preferable. Fur-
thermore, the outline of an inventive primitive can also be determined by a
geometric
pattern, e.g. the outline form of a snowflake or a guilloche pattern.
[0017] The nonlinear primitives characterized by a certain outline fonn can
expe-
diently have a filling which is preferably executed substantially all over. It
is of
course also conceivable, however, that the filling is screened, e.g. in the
form of a dot
screen, or that the primitive is determined only by a line defining the
outline contour
and thus has no filling. In this case, the color of the layer or layers
located under the
primitive can be recognized in the nonfilled inner areas of the primitives.
[0018] The size of an inventive nonlinear primitive will hereinafter be
understood
to be its dimension in one or more directions. Although it can be expedient
for certain
uses in the product production area to provide primitives with a dimension in
the
range of a few millimeters, it is particularly preferable if the nonlinear
primitives have
a dimension of 10 m to 500 m, in particular 20 m to 250 m. It goes without
say-
ing that a small dimension will increase the protection from forgery of the
claimed
security elements having an optically variable structure. Therefore, in
particular coat-
ings with a dimension of the primitives of e.g. 30 gm offer very great
protection from
forgery. At the same time, the dimension of the primitives is of course to be
provided
so as to permit the production of high-quality inventive security elements.
[0019] Unlike the coatings known for example from CA 10 19 012 having printed
line patterns in which the dimension of the lines in the longitudinal
direction is con-
siderably higher than the dimension of the lines in the transverse direction,
the inven-
tive nonlinear primitives preferably have an outline form in which no
dimension in
any direction is more than four times the dimension in one of the other
directions of
the primitive.
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[0020] For it has turned out that particularly impressive tilt effects of the
optically
variable structures, at the same time as great freedom of design for the
inventive coat-
ing, can be obtained when the inventive primitives have a form that does not
differ
too much from the outline form of a circle, triangle or square, i.e. a compact
element.
In such bodies, no dimension in any direction is more than approximately twice
a di-
mension in one of the other directions.
[0021] The coatings comprising the inventive nonlinear primitives can be a
printed
layer, in particular an offset, intaglio, screen, flexographic, xerographic,
ink-jet or
thermographic printed layer. Each of the stated printed layers has certain
properties
that are per se known to the expert, depending on the method used therefor.
The
choice of a certain printed layer will therefore depend firstly on the
intended use of
ink, desired embossed structure, resolution, provided picture motif, etc.
[0022] Furthermore, it is preferred if the coating comprising nonlinear
primitives is
a layer incorporated by a laser printer or by the action of laser radiation of
a laser.
Depending on the material used for the substrate of the optically variable
structure,
possible radiation sources here are CO2lasers, Nd:YAG lasers or other types of
laser
in the wavelength range from ultraviolet (UV) to far infrared (IR), whereby
the lasers
often also work with frequency doubling, tripling or even greater harmonic
genera-
tion. However, it is preferable to use laser sources in the near IR, since
this wave-
length range well matches the absorption properties of the materials provided
for the
optically variable structures. Since the spot size of the laser radiation can
vary from a
few microns to a few millimeters depending on the application case, the
inventive
primitives can be advantageously produced by the use of laser radiation. The
continu-
ous power of the lasers used therefor is normally between a few watts and a
few hun-
dred watts.
[0023] The inventive coating can fundamentally be formed from nonlinear primi-
tives of any arrangement. Besides a completely random arrangement, e.g. an ar-
rangement in the form of a fractal pattern is also possible. However, it is
particularly
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preferable if at least a part of the nonlinear primitives is disposed in a
preferably peri-
odic grid. A grid arrangement of the primitives defines preferred directions
of the
coating which, when combined with a suitable embossed structure, lead to
particu-
larly impressive tilt effects. Although it is fundamentally possible that only
a part of
the nonlinear primitives is disposed in the form of a grid and the other part
not in grid
form, it is particularly expedient if all primitives forming the coating are
disposed in
the form of a grid, in particular periodic grid.
[0024] Independently of whether the primitives are disposed randomly or in a
grid,
primitives of different colors can overlap and produce a secondary color in
the over-
lap areas, whereby the arrangement of secondary colors in the overlap areas
can in
turn be per se a security feature of the coating.
[0025] According to a preferred embodiment, it is provided that groups of at
least
two nonlinear primitives of different color are disposed in the form of color
primi-
tives. The choice of colors and of type of primitives of a color primitive is
fundamen-
tally free, but colors of a primary color system are preferred. The use of
color primi-
tives permits the representation of elaborate and highly detailed picture
motifs and
geometric patterns, among other things.
[0026] The arrangement of the color primitives can again be effected
completely
randomly, in the form of a fractal pattern or in a combination of said two
possible
arrangements. It is particularly preferable, however, if at least a part of
the color
primitives is disposed in an, in particular periodic, grid. Such an
arrangement is par-
ticularly suitable for representing color pictures and similar motifs. It is
of course also
conceivable that a relatively large number of color primitives is disposed in
a grid and
the coating simultaneously has nonlinear primitives disposed randomly or
likewise in
grid form.
100271 Although the primitives or color primitives can be disposed in a grid
with
varying grid spacing, it is particularly expedient if the grid spacing of the
grid is con-
CA 02642330 2008-08-13
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stant for a part or the total coating. The thereby obtained regular
arrangement defines
one or more preferred directions in the plane of the coating and opens up, in
combina-
tion with an appropriately disposed embossed structure, particularly striking
tilt ef-
fects for the viewer.
[0028] The coating coinprising nonlinear primitives, or color primitives
formed
therefrom, can contain primitives of any color. However, primitives in the
colors of a
primary color system are particularly preferable. Furtherinore, coatings are
claimed
that have color primitives with nonlinear primitives in the colors of a
primary color
system. All primary color systems can be used that permit the application of a
coating
for the optically variable structure by the printing methods already
described. How-
ever, it is particularly preferable to use the primary color systems RGB (red,
green,
blue), CMY (cyan, magenta, yellow) and CMYK (cyan, magenta, yellow, key
(black)).
[0029] It is furthermore particularly expedient if the optically variable
structure has
a multiplicity of color primitives that represent, upon perpendicular viewing,
a multi-
colored picture motif and/or geometric pattern whose visual impression varies
upon a
change of viewing angle. The color primitives representing the picture motif
or pat-
tern can have nonlinear primitives of any color or elements in the colors of a
primary
color system. As mentioned above, suitable embossing of the inventive coating
makes
it possible to produce elaborately designed and highly detailed picture motifs
that are
substantially completely visible in a top view, but upon a change of viewing
angle
only partly visible due to the shadowing effect.
[0030] In a special einbodiment, the color primitives correspond to the pixels
of
the picture motif and/or geometric pattern, said pixels having certain color
compo-
nents of a color system associated therewith. The color primitives have
nonlinear
primitives with colored areas in the colors of the color system, the size of
the colored
areas of the nonlinear primitives corresponding to the particular color
component of
the pixels. The color effect of a color primitive therefore results for the
viewer from
CA 02642330 2008-08-13
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the size of the areas covered with the particular colors. The areas can be
directly adja-
cent each other or also maintain a certain distance apart so that the color
effect of the
color primitive is ultimately also influenced by the color of the light
reflected by the
base surface. According to this special embodiment, it is thus possible to
represent
picture motifs and geometric patterns in true colors, whereby the number of
pixels of
the picture motif or pattern at the same time corresponds to the number of
color
primitives. It should be noted that, in a top view, the true color of a color
primitive
results as the secondary color of the nonlinear primitives forming the color
primitive
if the dimensions of the colored areas are below the viewer's visual
resolution.
100311 According to a further advantageous embodiment of the security element,
it
is provided that at least two grids coinprising nonlinear primitives of one
color in
each case form a picture motif and/or geometric pattern. The arrangement of
the grids
defines areas in which the nonlinear primitives of different grids overlap and
produce
a secondary color in said areas. To produce as definite a secondary color as
possible
in the overlap area, nonlinear primitives with a well defined outline fonn and
an all-
over filling are particularly preferable for forming the grids. The grids can
of course
contain primitives in the colors of a primary color system, thereby causing
the secon-
dary colors produced in the overlap areas to in turn be well defined secondary
colors
of a subtractive color mixture. Since the grids used do not cover the
substrate material
all over as a rule, there is light reflection in the bare areas of the
substrate. The re-
flected light and the overlap areas of subtractive color mixture ultimately
yield an
additive (autotypic) color mixture perceived by the observer.
[0032] It is further particularly preferable if the areas of overlapping
primitives
correspond to the pixels of the picture motif and/or geometric pattern, said
pixels hav-
ing certain colors of a color system associated therewith, and the secondary
color of
the areas of overlapping primitives corresponds to the particular color of the
pixels, so
that the color effect of the picture motif and/or geometric pattern varies
upon a
change of viewing angle. In this case, a pixel of the motif or pattern is thus
repre-
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sented by a secondary color produced by subtractive color mixture. Depending
on the
degree of coverage of the substrate by the overlap areas of the grids, an
additive color
mixture ultimately also results for the viewer to a certain degree through the
light re-
flected by the substrate.
100331 If the nonlinear primitives or color primitives are disposed in the
form of a
grid, such a regular arrangement of the primitives or color primitives defines
at least
one preferred direction in the plane of the coating. It is particularly
preferable that the
linear embossed elements are disposed in the direction of the at least one
preferred
direction at least in certain areas, so that when the areas provided with
embossed
structures are viewed perpendicular to the at least one preferred direction
the visual
impression varies in dependence on viewing direction. For it has turned out
that the
tilt effect perceptible to the viewer upon a change of viewing angle is
particularly
pronounced with an arrangement of the embossed elements in a preferred
direction.
The tilt effect will furthermore be particularly impressive if different areas
of the
coating are provided with embossed elements that are disposed in a preferred
direc-
tion in each case. The preferred direction itself can be caused by the outline
fonn
and/or the arrangement of the primitives or color primitives in the grid.
Therefore, a
preferred direction can be defined by the arrangement and simultaneously by
the out-
line contour of the primitives forming the grid.
[0034] The optically variable structure can have additional information which
arises by variation of the coating and/or of the embossed structure. The
additional
information can be recognizable from one or more viewing directions. It is
also pos-
sible that the additional infonnation runs into second, third, etc.,
additional informa-
tion depending on the viewing angle.
[00351 The additional information can arise for example by a variation of the
fonn,
color and/or the arrangement of the nonlinear primitives, such as offset,
change of
grid spacing, omission, reflection of single or several nonlinear primitives.
The addi-
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tional information can also have information in the coating that
individualizes the
optically variable element, such as alphanumeric characters or bar codes.
[0036] Although the inventive optically variable structure of the security
elements
can contain linear embossed elements of any arrangement, it is particularly
preferable
if the embossed elements are disposed in the form of an embossed grid with a
grid
spacing. The grid spacing of the embossed structure can correspond to the grid
spac-
ing of the coating grid. If the grid spacings of the coating and of the
embossed struc-
ture are not identical but shifted by a certain value, however, this yields
interesting
beat effects dependent on viewing direction.
[0037] The additional information can advantageously also arise by a variation
of
the form, size, height and/or the arrangement of the linear embossed elements,
such as
offset, change of grid spacing, omission of single or several linear embossed
ele-
ments. The additional information by variation of the embossed structure is
strength-
ened by a simultaneous variation of the coating.
[0038] In a further advantageous embodiment, it is provided that the optically
vari-
able structure is subdivided into partial areas in which different partial
embossed
structures and/or partial coatings are disposed. If the linear embossed
elements of the
embossed structure or the nonlinear primitives are disposed in the fonn of a
grid with
a grid spacing, an expedient embodiment results from the partial embossed
structures
or partial coatings being offset in at least two adjacent partial areas by a
fraction, in
particular a third, of the grid spacing. Furtherinore, parts of the partial
embossed
structures can also have an unembossed edge contour so as to be better
recognizable.
[0039] In connection with this matrix-like arrangement of the partial embossed
structures and the production of additional information in the area of the
embossed
structures or the coating, express reference is made here to WO 97/17211 and
WO
02/20280 Al.
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[0040] The inventive optically variable structure forms a security element
that is
difficult to imitate and can be disposed directly on any data carriers. The
optically
variable structure can also be part of a security element having further
security fea-
tures besides the optically variable structure.
[0041] The security element can for example have in the area of the optically
vari-
able structure a further ink layer which is preferably translucent and which
is dis-
posed congruently with the raised areas of the embossed structure. Here, too,
a great
variety of embodiments are possible. Some are for exainple already described
in WO
2004/022355 A2, to which express reference is likewise made in this
connection.
[0042] According to a further embodiment, the security element can have
further
layers and authentication features, such as a metallic layer, a metallic
effect layer, an
additional translucent, optically variable layer or a foil element. Such
layers and ele-
ments can be superimposed on optically variable structures or underlaid
thereunder.
The coating combined with the linear embossed elements can of course also be
such a
metallic layer, a metallic effect layer or optically variable layer.
(0043] Finally, it is also possible to equip the coating or the printing inks
used for
producing the primitives and color primitives, and/or the ink layer disposed
congru-
ently with the raised areas of the embossed structure, at least partially with
machine-
readable properties. For this purpose it is possible to use e.g. magnetic,
electrocon-
ductive, luminescent additives. Additives absorbent in a certain wavelength
range,
preferably in the UV or IR region, can also be used advantageously.
[0044] The inventive optically variable structure or the inventive security
element
is preferably applied to data carriers, such as security documents and value
docu-
ments, such as bank notes, shares, bonds, certificates, coupons, credit cards
or identity
cards, passports or the like. The data carriers are thus equipped with a
security ele-
ment easily recognizable even to laymen for increasing the falsification
security.
However, the optically variable structure or the inventive security element
can also be
CA 02642330 2008-08-13
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used very advantageously in the area of product protection. Here, the
optically vari-
able structure or the security element can be applied to suitable labels or
packages or
the goods themselves.
[0045] If paper is used as the data carrier material, it is possible to use in
particular
cotton vellum papers, paper-like materials made of plastic films, plastic-film-
coated
or laminated paper or multilayer composite materials.
[0046] For producing the inventive security element or the optically variable
struc-
ture, any substrate is preferably first provided with the coating comprising
nonlinear
primitives, and the embossed structure then produced in register with said
coating.
However, it is fundamentally also possible to provide the method steps in the
reverse
order. The coating is preferably printed on or transferred to the substrate by
the ther-
motransfer method here. The coating can be produced by any printing process,
such
as planography, e.g. the offset process, relief printing, e.g. the letterpress
or flex-
ographic process, screen printing, gravure printing, e.g. halftone gravure or
intaglio
printing, or a thermographic process. Furthermore, the coating can preferably
also be
produced by a laser printer or by the action of laser radiation.
[0047] For producing the einbossed structure, any methods can likewise be
used.
The embossed structure is preferably produced by means of an embossing tool,
which
can be for example an intaglio printing plate. The embossing is produced here
as a
blind embossing with the help of an inkless intaglio printing plate. According
to a
special embodiment, however, the embossed structure can also be produced by
inta-
glio printing with ink. This production variant can be used in particular for
embodi-
ments in which a further ink layer is provided congruently with the embossed
struc-
ture.
[0048] For producing the embossing tool, a plate surface is for example milled
with a graver or a laser. The plate surface used can be any material, such as
copper,
brass, steel, nickel or the like. The graver used for milling preferably has a
flank angle
CA 02642330 2008-08-13
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of approx. 40 and a rounded point approaching a spherical segment or sector.
The
embossing tool can be milled as a one-up unit or already as a multi-up unit.
[0049] The order of the two method steps can fundamentally be selected freely.
As
a rule, the coating is first applied and then embossed. The relief height and
shaping of
the embossing is thus spared from further influences occurring for example in
a sub-
sequent printing operation.
[0050] The alternative, namely first embossing and then applying the coating,
of-
fers the advantage of higher color brilliance and a more sharply contoured
print, how-
ever. This effect comes from the fact that the substrate is simultaneously
calendered
during embossing and thus acquires a smoother, less absorbent surface.
[0051] Furtherinore, application of the coating before embossing offers the
advan-
tage that the coating can be disposed solely on the flanks of the embossed
elements or
else solely in the zeniths/amplitudes of the embossed elements. This makes it
possible
to obtain particularly impressive shadowing effects. Unlike intaglio printing
with ink,
in which embossing and application of the coating are effected simultaneously
and the coating can be disposed solely in the area of the zeniths/amplitudes
of the em-
bossed elements, the separation of the method steps of embossing and
application of
the coating opens up much greater latitude for design. In particular a process
control
by which the coating is first disposed on the substrate and the embossed
structure is
then produced with high register accuracy permits the above-mentioned
selective ar-
rangement of the coating solely on the flanks of the embossed elements, while
the
zeniths/amplitudes of the embossed elements have no coating. With respect to
the
arrangement of the coating solely in the zeniths/amplitudes or flanks of the
embossed
elements, the disclosure of WO 97/17211 is included in the present
application. Fur-
thermore, the description of the figures of the present application will also
indicate
further details and advantages for the selective arrangement of the coating on
the
flanks or the zeniths/amplitudes.
CA 02642330 2008-08-13
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[0052] With reference to the following examples and supplementary figures, the
advantages of the invention will be explained. The described single features
and sub-
sequently described embodiments are inventive when taken alone but also
inventive
in coinbination. The examples represent preferred embodiments, but without in
any
way restricting the invention. The proportions shown in the figures do not
correspond
to the relations existing in reality and serve solely to improve the
clearness.
[0053] The schematic drawings are described as follows:
Fig. 1 an inventive data carrier,
Fig. 2 a section along the line A-A from Fig. 1,
Fig. 3 a first inventive coating in a top view,
Fig. 4 a second inventive coating in a top view,
Fig. 5 a third inventive coating in a top view,
Fig. 6 a fourth inventive coating in a top view,
Fig. 7 a fifth inventive coating in a top view,
Fig. 8 a sixth inventive coating in a top view, which is a variant of the
coating of
Fig. 7,
Fig. 9 an embossed structure with linear embossed elements in a top view,
Fig. 10 a further inventive coating with nonlinear primitives disposed in the
fonn
of a grid,
Fig. 11 a perspective view of an inventive optically variable structure formed
from
the embossed structure and coating shown in Fig. 9 and Fig. 10, respec-
tively,
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Fig. 12 a further embossed structure with nonlinear embossed elements,
Fig. 13 a further inventive coating with nonlinear primitives disposed in the
fonn
of a grid,
Fig. 14 a perspective view of a further inventive optically variable structure
formed from the embossed structure and coating shown in Fig. 12 and Fig.
13, respectively,
Fig. 15 a further inventive coating with three different types of nonlinear
primi-
tives which are disposed in the form of a grid,
Fig. 16 the inventive coating from Fig. 15 with preferred directions marked
for
three areas of the coating,
Fig. 17a a further inventive coating with nonlinear primitives disposed in
grid fonn,
Fig. 17b the coating from Fig. 17a with three marked preferred directions and
sche-
matically shown embossed structures corresponding thereto,
Fig. 18a a further inventive coating with nonlinear primitives disposed in
grid forin,
Fig. 18b three preferred directions resulting from the grid arrangement
according to
Fig. 18a,
Fig. 18c a further inventive coating with color primitives disposed in grid
form,
Fig. 18d three preferred directions resulting from the grid arrangement
according to
Fig. 18c,
Fig. 19 a further inventive coating with color primitives disposed in grid
form, the
coating having additional information,
Fig. 20 a detail of a picture motif shown in Fig. 1, in a black-and-white
representa-
tion,
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Fig. 21 the detail according to Fig. 20 in the form of an inventive coating
with
nonlinear primitives disposed in grid form,
Fig. 22 the detail from Fig. 20 in the fonn of a further inventive coating,
Fig. 23 a further inventive coating with color primitives disposed in the form
of a
grid,
Fig. 24 the coating of Fig. 23 with two preferred directions resulting from
the grid,
and embossed elements disposed along said preferred directions, in a top
view,
Fig. 25 a detail of Fig. 20 with a preferred direction for the arrangement of
the lin-
ear embossed elements,
Fig. 26 a further picture motif with a plurality of preferred directions for
the ar-
rangement of the linear embossed elements,
Fig. 27 a further embossed structure with linear embossed elements,
Fig. 28 a further inventive coating with nonlinear primitives disposed in the
forln
of a grid, whereby nonlinear primitives of different grids overlap in certain
areas,
Fig. 29a a further inventive coating with overlapping primitives of different
colors
and three preferred directions of the coating,
Fig. 29b the inventive coating from Fig. 29a with additional information
disposed in
the coating,
Fig. 29c the inventive coating from Fig. 29a with further additional
infonnation
disposed in the coating,
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Fig. 30 a further inventive coating with a marked direction which does not
corre-
spond to a preferred direction of the coating,
Fig. 31 a cross section through an embossed structure with additional
information,
Fig. 32 a further embossed structure in cross section with different
additional in-
formation,
Fig. 33 a further embossed structure in cross section with embossed elements
which are disposed in a grid with large grid spacing,
Figs. 34a-34p cross sections through different linear embossed elements,
Fig. 35a an inventive data carrier in cross section before embossing,
Fig. 35b an inventive data carrier in cross section after embossing,
Fig. 36a a further inventive data carrier in cross section before embossing,
Fig. 36b the further inventive data carrier after embossing done with ink.
100541 Fig. 1 shows an inventive data carrier 1 in the fonn of a bank note
with an
optically variable structure 3 which is placed in the printed image area 2 of
the data
carrier 1 and in the unprinted area. The optically variable structure 3 is
used accord-
ing to the invention as a so-called human feature, i.e. as a feature testable
by a human
without aids, possibly alongside further features for detecting the
authenticity of the
data carrier. Providing such features is particularly expedient in bank notes,
but also
in other cash-equivalent documents, such as shares, checks and the like. Data
carriers
according to the invention may also be labels, passports or cards as are used
nowa-
days e.g. for identifying persons or goods or for performing transactions or
services.
[0055] The optically variable structure 3 can be of different structure, in
conjunc-
tion with the resulting different effects from different viewing directions.
According
to a preferred embodiment, the optically variable structure 3 consists of a
one or
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multi-colored coating contrasting with the surface of the data carrier, such
as a pat-
tern, picture or alphanumeric information, which is produced by printing
technology
or in another way, for example by a transfer method or by the action of laser
radia-
tion. Depending on the design of coating and einbossed structure and their
mutual
association, the embossed structure interacting with the coating produces the
inven-
tive effects to be used for the authenticity check.
[0056] All optically variable structures according to the invention have in
common
that they and the resulting effects cannot be imitated using currently known
reproduc-
tion techniques, in particular copying machines, since copying machines can
only
render the optically variable structure from one viewing direction so that the
optically
variable effect is lost. Furthermore, imitation will generally also fail
because the reso-
lution of the reproduction apparatuses is too low.
[0057] Hereinafter, some examples of different preferred embodiments of the in-
vention will be explained with reference to the figures. The representations
in the fig-
ures are greatly schematized for purposes of better understanding and do not
reflect
the actual conditions.
[0058] The embodiments described in the following examples are reduced to the
essential information for better comprehensibility. In actual iinplementation
it is pos-
sible to use considerably more complex patterns or pictures in single- or
multicolor
printing as a coating. The same applies to the embossed structures. The
information
represented in the following examples can likewise be replaced by picture or
text in-
formation as elaborate as desired. Production of the coating e.g. as a print
normally
exploits the possibilities of printing technology. Typical dimensions of
nonlinear
primitives as of approx. 10 m are used. The linear embossed elements forming
the
embossed structure have as a rule an embossing height in the range of 10 m to
250
gm, preferably 50 m to 120 gm. The various embodiments are not restricted to
use
in the described form either, but can also be combined with each other to
enhance the
effects.
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[0059] Further, only the design and mutual association of the embossed
structure
and the coating are shown in the following examples to perinit a clear
presentation of
the optical effects of the inventive optically variable structure.
Example 1(Figures 2 to 14 and Fig. 34) [0060] Fig. 2 shows a schematic
sectional view along the line A-A (see Fig. 1) and
in connection with Figures 3 and 4 of an optical variable structure in which
the em-
bossed structure 4 is formed of regularly disposed, uniform, linear embossed
elements
5, i.e. designed as a periodic line screen. The linear embossed elements 5 are
provided
with a coating 7 which is formed as a multi-colored arrangement of nonlinear
primi-
tives. The individual color areas of the nonlinear primitives are located on
the flanks
of the linear embossed elements. The formation of the linear embossed elements
5 as
elevations, which are preferably produced by embossing the data carrier, can
be
clearly recognized in the sectional view on the upper side of the data
carrier. If the
data carrier is mechanically defonned with an embossing tool, the underside of
the
data carrier material shows the negative deformation. The defonnation is shown
only
schematically here. The back of the data carrier will in general not have an
embossing
that is so pronounced and true to the embossing die. Hereinafter, only the
upper or
front side of the data carrier essential for understanding the invention will
be de-
scribed as it is perceived by the viewer in a top view from the viewing
direction AU.
Deformation of the underside or back is not essential to the invention but
merely con-
comitant to special embossing techniques, such as intaglio printing. However,
it can
serve as a further authentication feature.
[0061] The inventive coating 7 is shown more closely in Figures 3 and 4.
Accord-
ing to Fig. 3 the coating 7 is formed from nonlinear primitives 8 and 13
disposed
regularly in the form of a grid. The elements 8 and 13 are of different
colors, which is
symbolized by the different filling of the circles fonning the primitives 8
and 13. Be-
sides the primitives with a circular outline form shown in Fig. 3, two further
outline
fonns of the primitives are shown in Fig. 4. The outline of the primitives 13
is that of
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a syinmetrical cross, whereas the outline of the elements 8 corresponds to a
star,
which can also be regarded as a special decagon. The primitives 8 and 13 of
Fig. 4 are
also disposed in grid form. The elements 13 in Figures 3 and 4 are offset from
the
elements 8 by half a grid spacing in a direction 17 extending from below to
above in
Fig. 3. The nonlinear primitives 13 are also offset from the primitives 8 in a
direction,
not specified in Figures 3 and 4, perpendicular to the direction 17.
[0062] The preferred direction 17 oriented from below to above in Fig. 3 is
defined
by the grid arrangement of the primitives 8 and 13. Along said preferred
direction 17
a linear embossed element of the embossed structure can be disposed so that
the
structure comprising coating 7 and embossed structure 4 as shown in cross
section in
Fig. 2 ultimately results if the primitives 8, 13 are so embossed with the
embossed
element 5 that they come to lie approximately symmetrically to the center of
the em-
bossed element. To arrive at the structure of Fig. 2, a linear embossed
element 5 with
an approximately semicircular cross section, as shown in Fig. 34d, must
further be
produced in the substrate.
[0063] To obtain a sharper tilt effect, a cross section according to Figure
34c or
34h can be selected for the embossed elements. Even greater strengthening of
the tilt
effect results from the choice of a profile according to Figure 34a, 34b or
34f. Fur-
thermore, other embossed element cross sections shown in Fig. 34 can also be
com-
bined advantageously with the coating 7.
[0064] As can be easily seen in Figures 2 and 3, the total coating formed from
the
primitives 8 and 13 is visible in a substantially perpendicular top view of
the inven-
tive optically variable structure. Upon a change of viewing direction from the
top
view (AU) to an oblique view from direction B, however, the primitives 8
disposed
on a flank of the linear embossed elements 5 will dominate the visual picture,
while
the primitives 13 disposed on the other flank of the linear embossed elements
5 are
partly or completely concealed (shadowed) by the embossed elements 5. Upon
oblique viewing of the optically variable structure from direction C, the
primitives 13
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dominate the visual impression and the primitives 8 are wholly or partly
shadowed.
This basic principle inherent in the inventive optically variable structures 3
is realized
analogously if the linear embossed elements 5 are not straight, as in Fig. 3,
but have
the fonn of a wavy or curved line. The line 6 shown for illustrating such an
emboss-
ing in Fig. 4 is only for illustration's sake. It is of course also possible
to emboss a
considerably more complicated pattern, e.g. a spiral pattern, into the base
surface.
[0065] Hereinafter, further inventive coatings will be described with
reference to
Figures 5 to 8. The coating 7 in Fig. 5 shows primitives 8, 9 of different
color whose
outline form corresponds to that of a symmetrical "L". The primitives 8 and 9
are dis-
posed in a regular grid in such a way that a primitive 8 is combined with a
primitive 9
in each case. The primitives 8 and 9 thus form in pairs a color primitive 52,
which
will be dealt with in more detail.
[0066] A further variant of the coating 7 is shown in Fig. 6. The coating 7
here
consists of regularly disposed, nonlinear primitives 8, 9 and 13 which in each
case
have the outline form of an arched element. The primitives assume the
positions of a
grid with constant grid spacing.
[0067] It is also possible that the primitives, as shown in Figures 7 and 8,
have an
outline form complementary to the outline form of an adjacently disposed
primitive
so as to yield a substantially all-over coating 7. While having basically the
same out-
line fonn, the elements can also be disposed so as to yield additional
inforination in
the coating, as shown in Fig. 8.
[0068] With reference to Figures 9 to 14, further inventive optically variable
struc-
tures will be dealt with in detail. Fig. 9 shows an embossed structure 4
consisting of
three linear embossed elements 5 with a triangular cross section. Each
embossed ele-
ment 5 has four flanks which rise above the plane formed by the substrate. The
flanks
extending in the longitudinal direction of the linear embossed element 5 are
desig-
nated with the reference signs 5a and 5b in Fig. 9, while the two flanks
present at the
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ends of the embossed element 5 are provided with the reference signs 5c and
5d. The
grid spacing of the grid determining the arrangement of the linear embossed
elements
is designated x.
[0069] Fig. 10 shows a coating 7 that yields in combination with the embossed
structure of Fig. 9 the optically variable structure shown in Fig. 11. The
coating 7
consists of two types of nonlinear primitives with a different outline and
different
color. The primitives 8 have a polygonally bounded outline form in the form of
a rec-
tangle. Each primitive 9, however, has the outline form of a square and an
area ap-
proximately half as great as the area of a primitive 8. The primitives 8 and 9
are dis-
posed at regular intervals on the positions of a grid. Each pair of primitives
8 and 9
forms a color primitive 52 which is disposed in a grid cell 12. The grid
spacing x of
the coating 7 corresponds to the grid spacing x of the embossed structure 4 of
Fig. 9.
[0070] When a substrate provided with the coating 7 is provided in exact
register
with the embossed structure 4 from Fig. 9 this yields the combined structure
from Fig.
11. While the total coating 7 is visually ascertainable in a vertical top view
of the
structure shown in Fig. 11, fundamentally only the grid arrangement of the
nonlinear
primitives 9 on the flanks 5b of the embossed elements 5 can be perceived upon
oblique viewing from direction B. Conversely, only the primitives 8 on the
flanks 5a
of the linear embossed elements 5 can be seen from viewing direction C. With
the
arrangement of the primitives 9 at the base of each flank 5b as shown in Fig.
11, the
primitives 9 disposed between a plurality of linear embossed elements 5 are
shad-
owed very quickly by the flanks 5b of adjacent embossed elements 5 when the
angle
of vision changes from a substantially perpendicular top view (AU in Fig. 2)
to view-
ing from direction B. Since the primitives 8 are so disposed, on the other
hand, that
they come to lie on the flanks 5a of the embossed elements 5 close to the
amplitude
20, they can be seen on the flanks 5a over a wide angular range due to the
lesser
shadowing by the embossed elements upon a change of viewing from a
substantially
perpendicular top view to oblique viewing from direction C.
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[0071] Fig. 12 shows an embossed structure 4 varied with respect to the
structure
shown in Fig. 9. It comprises a linear embossed element 5 extending along a
first pre-
ferred direction 16. Perpendicular thereto, three further linear embossed
elements 15
are disposed along a second preferred direction 17. The grid spacing of the
embossed
element 5 is x, the grid spacing of the embossed elements 15 is y. In the
present case
the grid spacings x and y are equal.
100721 Fig. 13 shows an inventive coating 7 which is fonned by a grid
arrangement
of the nonlinear primitives 8 and 9, both primitives having a rectangularly
bounded
outline form and different colors. The primitives 8 and 9 again form a color
primitive
52 which is disposed in a grid cell 12. The combination of the embossed
structure 4
from Fig. 12 and the coating 7 from Fig. 13 yields the combined structure
shown in
perspective in Fig. 14. Viewing from directions B and C yields this time a
completely
different picture from Fig. 11, since the linear embossed elements 5 and 15
are dis-
posed along two preferred directions. From direction C substantially only the
primi-
tives 8 disposed on the flanks 5a can be seen, while from direction B the
primitives 9
disposed on the flanks 5b, unless they are shadowed by adjacent embossed
elements.
100731 From direction D, on the other hand, the elements 8 can be seen, and
from
direction E the elements 9. The arrangement of the primitives on the
particular flanks
of the embossed elements also has an influence on the color shift effect of
this struc-
ture.
Example 2 (Figures 15 and 16)
100741 The inventive coating 7 shown in Figures 15 and 16 comprises three
types
of different-colored and nonlinear primitives 8, 13 and 39 which are in each
case dis-
posed in the fonn of a grid with constant grid spacing. Furthermore, one
primitive 8,
13 and 39 in each case are printed on the substrate (not specifically shown)
so as to
form a color primitive 52. In accordance with the regular arrangement of the
individ-
ual elements, the color primitives 52 are also disposed in the form of a
regular grid
CA 02642330 2008-08-13
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with constant grid spacing. One color primitive 52 is located in a grid cell
12 of the
grid in each case. The thus obtained regular arrangement of color primitives
52 is di-
vided into three partial areas A, B and C in the shown preferred embodiment.
Each
partial area is provided with an embossed structure 4 (not shown) comprising
linear
embossed elements 5. The alignment of the embossed structure 4 is effected in
each
partial area parallel to the preferred directions of the grid, whereby in Fig.
16 only
one preferred direction is marked for each area A, B and C and used for
aligning the
embossed structure. As in the above-described optically variable structures,
an opti-
cally variable effect dependent on viewing direction results for the embossing
of the
coating 7 shown in Figures 15 and 16. While in a top view the total coating 7
can be
perceived by a viewer, any other oblique viewing directions yield interesting
tilt ef-
fects which are different for the single areas A, B and C since the embossed
structures
in each case have different orientations in said areas.
Example 3 (Figures 17a, 17b, 18a and 18b)
[0075] The coating 7 shown in Figures 17a and 17b is formed from three
circular
primitives 8, 9 and 13 of different color which again define a color primitive
52 in a
grid cell 12 of a regular grid. The arrangement of the primitives 8, 9 and 13
again de-
termines preferred directions along which an embossing is effected. In Fig.
17b the
preferred directions 16, 18 and 19 are marked and the embossed structures 64
shown
schematically along the preferred directions. The cross section of the linear
embossed
elements is triangular and corresponds to the cross section shown in Fig. 34a.
The
embossed structure 64 has amplitudes or zeniths 20 and valleys 21 located
therebe-
tween. Therefore, the nonlinear primitives 8 and 9 come to lie on one flank of
the
nonlinear embossed element upon an embossing of the coating 7 along the
preferred
direction 16, while the elements 13 come to lie on the other flank of the
element.
[0076] If the dimensions of the primitives 8, 9 and 13 are selected so that
they are
no longer perceived as separate elements by the human eye, a secondary color
recog-
nizable in a top view results for a color primitive 52 defined by the
primitives 8, 9 and
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13. Depending on the area coverage of the color primitive 52 in the grid cell
12, the
viewer perceives a secondary color resulting from the secondary color of the
color
primitive 52 and the color of the substrate surface on which the coating is
disposed.
Upon viewing from a direction different from the perpendicular top view (AU in
Fig.
2) a secondary color resulting from the colors of the primitives 8, 9 and the
color of
the substrate surface is observed in the area of the linear embossing along
the direc-
tion 16 on a flank of the embossed element. From a direction opposite this
viewing
direction, however, the secondary color comprising the color of the primitives
13 and
the color of the base surface is perceived on the other flank of the embossed
element.
It is evident from Fig. 17b that the secondary color resulting for the
individual flanks
of the embossed element changes in case of an embossing along the preferred
direc-
tion 19. In this case, a secondary color comprising the colors of the
primitives 8, 9
and 13 and the color of the base surface results upon viewing of one flank.
The per-
ceived secondary color of the opposite flank, however, is defined by the color
of the
differently spaced elements 8, 9 and 13 and the color of the base surface.
[0077] Fig. 18a shows a further inventive coating 7 wherein triangular
primitives
8, 9 and 13 are disposed in the form of a relatively large regular triangle.
The ar-
rangement of the primitives 8, 9 and 13 again defines a color primitive in
each grid
cell 12 of a grid. Compared to the color primitives 52 shown in Fig. 17a the
color
primitives of Fig. 18a are characterized by a greater coverage of the base
surface.
Therefore, the color effect that can be perceived by the viewer in a top view
of a grid
cell is determined to a greater extent by the inherent color of the triangular
primitives
8, 9 and 13 or the color primitive. Furthermore, said primitives again define
preferred
directions in the plane of the coating 7, which are shown by the reference
signs 16, 18
and 19 in Fig. 18b. If an embossing is effected along said preferred
directions with an
embossed structure having a pointed profile, e.g. the profile from Fig. 34a,
34b or 34f,
this yields color shift effects with extremely pronounced dependence on
viewing di-
rection. If for example the colors of the primary color system CMY are used
for the
primitives 8, 9 and 13, this yields for the coating 7 in a top view a
substantially gray
CA 02642330 2008-08-13
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secondary color for the color primitives 52, which is somewhat brightened by
an e.g.
white inherent color of the substrate.
Example 4 (Figures 18c and 18d)
[0078] Figures 18c and 18d show a further variant of the inventive coating 7.
The
nonlinear primitives 8, 9 and 13 again form a color primitive 52 in a grid
cell 12 of a
regular grid. The triangular primitives 8, 9 and 13 have the colors of a
primary color
system, for example those of the primary color system CMY. In the shown
example,
the triangles 8 have the color cyan, the triangles 9 the color magenta and the
triangles
13 the color yellow.
[0079] Unlike the coating grid of Fig. 18a, the coating 7 from Fig. 18c
comprises
two grids which are offset in the horizontal direction (direction 16 in Fig.
18d). As is
apparent from Fig. 18c, the color primitives 52 of the first and third lines
of the
shown coating belong to a grid, while the color primitives 52 of the second
line are
disposed in the grid cells 62 of the second grid. The grid cells 62 are offset
from the
grid cells 12 of the first grid by half a grid spacing in the horizontal
direction 16.
[0080] Again, three preferred directions 16, 18 and 19 result for the
arrangement of
the linear embossed elements (see schematic embossed structure 64). If an
embossed
element is superimposed on the second line of the coating 7 in direction 16,
for ex-
ample, solely yellow triangles 13 come to lie on one flank of the embossed
element
with an e.g. triangular cross section. When viewing said flank the viewer
therefore
sees solely yellow triangles 13 and the color of the base surface, e.g. white,
ultimately
yielding a bright yellow color. Conversely, he can perceive on the other flank
of the
embossed element disposed in direction 16 a secondary color recognizable from
the
colors magenta and cyan of the primitives 9, 8 and the white base surface
areas.
[0081] Analogously, the arrangement of a linear embossed element along the pre-
ferred direction 18 yields a perception dependent on viewing direction,
whereby one
flank of the embossed element, due to the magenta triangles solely disposed
there,
CA 02642330 2008-08-13
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shows a magenta color brightened by the color of the base surface. Viewing of
the
other flank of the embossed element, however, yields a secondary color from
the
color of the base surface and the colors yellow and cyan of the primitives 13,
8.
[0082] Finally, the arrangement of an embossed structure along the preferred
direc-
tion 19 will yield for one flank the pure brightened color cyan, and the other
flank a
secondary color from the color of the base surface and the colors magenta and
yellow
of the primitives 9, 13.
100831 A top view of the coating 7 of Figures 18c and 18d again yields for
each
color primitive a gray secondary color from the color of the primitives 8, 9
and 13.
The general impression of the coating is therefore again a somewhat brightened
gray
tone due to the white hue of the base surface. In the above discussion of
secondary
colors, a secondary color of the color primitives always results when the
dimensions
of the color areas of the individual primitives are below the resolution of
the human
eye.
Example 5 (Fig. 19)
[0084] Fig. 19 shows a coating 7 similar to the coating shown in Figures 18a
and
18b. However, in some grid cells of the coating 7 the arrangement of the
primitives 8,
9 and 13 of a color primitive 52 is different from the other grid cells 12.
The grid cells
with a different arrangement of the elements are provided with the reference
sign 22
and ultimately forin additional inforination within the coating. Depending on
the
alignment of the embossed structure with respect to the color primitives
disposed in
grid form, said additional information can be perceived in a top view and from
certain
directions. It constitutes an additional security feature which is inherent in
the inven-
tive coating 7.
CA 02642330 2008-08-13
-29-
Example 6 (Figs. 20 to 26)
[0085] Hereinafter, the production of secondary color effects by the inventive
opti-
cally variable structure will be dealt with in depth. Fig. 20 shows a detail
of the pic-
ture motif rendered in the printed image area 2 of the data carrier 1 of Fig.
1. It can be
disposed with nonlinear primitives of a color, e.g. black, on a substrate.
Furthermore,
an embossed structure is provided which extends in a certain direction in
certain areas
of the coating. An example thereof is shown in Fig. 25 for the eye area of the
picture
motif.
[0086] As shown in Fig. 21, the picture detail can also be effected by
nonlinear
primitives disposed in grid form, which have one or different outline fonns
and one
or different colors. In the present case, the coating of the picture motif is
fonned by
primitives 39 with a circular outline fonn, the primitives 39 having a filling
of vary-
ing degree for producing a coverage associated with a certain area of the
picture mo-
tif. For example, the primitives 39 are filled substantially completely in the
area of the
depicted person's hair, whereas the primitives 39 in the area of the forehead
are circu-
lar rings in whose center the color of the base surface, e.g. white, can be
perceived.
Furthermore, the color of the primitives can be varied for the individual
image areas.
[0087] Further, Fig. 22 shows the picture detail from Figs. 20 and Fig. 21
with a
coarser grid comprising primitives 13. A pair of arched or circular segment
shaped
primitives 13 is disposed in each case in a regular grid. By variation of the
area filling
of the individual primitives 13 the picture detail can be rendered with
sufficient con-
trast. It is of course also possible that a pair of primitives 13 of different
color is dis-
posed in each case so as to fonn a color primitive, and a certain color
primitive shows
in a top view a secondary color that is derived from the color of the
primitive pair and
the color recognizable in a grid cell from the base surface. The inventive
coatings
shown in Figures 21 and 22 are also provided with suitable embossed
structures,
whereby different alignments of the embossed elements are again provided in
single
image areas. Although a picture motif with straight partial areas defines a
multiplicity
CA 02642330 2008-08-13
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of preferred directions (see Fig. 26 with the preferred directions 16 to 19),
striking
preferred directions can also be found for the image areas of Figures 21 and
22, as
shown by way of example in Fig. 25.
[0088] The interaction of color primitives and linear embossed structure for
achieving impressive color shift effects with secondary colors will be
described in
detail with reference to Figures 23 and 24. The inventive coating 7 shown in
Fig. 23
can be a greatly enlarged detail of the picture motif of Fig. 21. Nonlinear
primitives 8,
9 and 13 of different color are disposed in the form of a grid with constant
grid spac-
ings x and y. One primitive 8, 9 and 13 in each case fonns a color primitive
52 which
is disposed in a grid cell 12 of the grid. Each color primitive 52 corresponds
to ex-
actly one pixel of a colored picture motif, e.g. the motif shown in Fig. 21.
Each pixel
of the picture motif has a certain color component of a color system
associated
therewith. In the present case, the primary color system CMY is used.
Accordingly,
the primitives 8, 9 and 13 of each color primitive 52 of the coating 7 have
the colors
cyan, magenta and yellow. The color component of a pixel is determined via the
size
of the colored areas of the primitives 8, 9 and 13. Due to its limited
resolution, the
human eye cannot perceive the primitives separately from each other and thus
recog-
nizes in a top view of the coating 7 only the secondary color of each color
primitive
52, defined by the color areas of the primitives. It should be noted that in
the case of
incomplete coverage of the base surface, the color of the base surface yields
an addi-
tional color component, but if a white base surface is selected this leads
only to a
brightening of the visually perceived secondary color of the color primitive
52. On
the other hand, a color primitive 52 can readily also be so designed that it
substan-
tially completely covers the area of a grid cell 12, so that solely the
secondary color
of the color primitive 52 defines the color of a pixel of the picture motif.
[0089) As shown in Fig. 23, the size of the colored area of a primitive is
varied in
such a way that the color component of each color primitive 52 is exactly
detennined.
CA 02642330 2008-08-13
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Therefore, in a top view of the coating 7 a picture motif to be represented
results in an
exactly defined color for each single pixel.
100901 The interaction of such a coating with linear embossed elements leads
to an
inventive optically variable structure as rendered in Fig. 24. The embossed
structure 4
comprises linear embossed elements 5 and 15, the former being disposed along
the
preferred direction 16 and the latter along the preferred direction 17. The
grid spacing
x and y of the linear embossed grids 5 and 15 corresponds exactly to the grid
spacings
x and y of the coating 7. Fig. 24 indicates that the arrangement of the
embossed ele-
ments in the area of the coating 7 virtually does not change the visual
impression in a
top view. That is, due to the limited resolution of the human eye, only the
secondary
color associated with a color primitive 52 is perceived in the area of a grid
cell 12 of
the coating. Upon viewing from an angle other than the top-view angle, e.g.
from the
direction 17, however, a completely different picture is perceived by the
viewer. For
exainple, only the color area of the primitive 8 is located on the flank 5a of
the em-
bossed element 5, while the color areas of the primitives 9 and 13 come to lie
on the
flank 5b. Accordingly, a secondary color defined by the color areas of the
primitives
9 and 13 and the color of the base surface results for the flank 5b within the
grid cell
12 of the embossed element 5, while the perceptible color for the flank 5a
within the
same grid cell 12 results from the inherent color of the primitive 8 and the
color of the
base surface. The same applies to each grid cell 12 of the coating 7 that is
provided
with an embossed structure. In this way it is possible to represent picture
motifs in
true colors and simultaneously provide the motifs with an impressive color
shift ef-
fect.
Example 7 (Figs. 27 to 29)
[0091] Figures 27 to 29 show a further variant of an inventive optically
variable
structure wherein tilt effects, and secondary color effects produced by the
overlapping
of primitives, are combined with each other. Fig. 27 shows an embossed
structure 4
with linear embossed elements 15. Unlike the embossed structure shown in Fig.
12,
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the embossed elements 5 and 15 of Fig. 27 have the cross sections shown in
Fig. 34g
and 34f, respectively.
[0092] Fig. 28 shows an inventive coating 7 which is coinbined with the
embossed
structure 4 from Fig. 27 to form an optically variable structure. The coating
7 is
formed from three types of nonlinear primitives 8, 9 and 13 which are in each
case
disposed in the form of a regular grid. In accordance with the grids formed by
the
primitives 8 and 9, primitives with a filling and thus a large area coverage
of the grid
are particularly well suited for this coating variant. Furthermore, it is
fundamentally
also possible to use other primitives, such as the alphanumeric characters 13.
It is evi-
dent from Fig. 28 that the arrangement of the primitives and thus of the grids
defines
the preferred directions 16 and 17. Also, the coating grid 7 has a grid
spacing x in
direction 17 and a grid spacing y in direction 16, which corresponds to the
grid spac-
ings of the embossed structure 4 from Fig. 27. The primitives of a grid have a
certain
color, e.g. the colors red, green and blue of the RGB primary color system. In
the ar-
eas defined by the arrangement of the grid, the primitives of the different-
colored
grids overlap and form a defined secondary color in said areas. The coating 7
thus
appears in a top view as an overlapping of different-colored grids which have
a sec-
ondary color in the overlap areas. The arrangement of the overlap areas
corresponds
to the pixels of a picture motif or a geometric pattern, so that in a top view
the picture
motif or pattern can be recognized in a grid comprising primary colors
corresponding
to the secondary colors. In combination with the embossed structure from Fig.
27 the
result is an optically variable structure displaying the above-described
coating in a top
view and the color structures dependent on the embossed structure 4 from other
view-
ing directions.
[0093] Figures 29a to 29c show further inventive coating grids 7. For reasons
of
clarity, the nonlinear primitives forming a grid are not shown singly,
although they
are spaced apart in a grid in the same way as in Fig. 28. As is evident from
Fig. 29a,
the grids formed from the primitives do not cross at right angles, so that
three pre-
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ferred directions 17, 37 and 47 result for one possible arrangement of the
embossed
structure. The arrangement of the grids in turn yields overlap areas of the
primitives
of different grids, so that the coating 7 yields in a top view a complicated
structure
comprising pixels with secondary colors and the pure colors of the primitives.
The
arrangement of the grids is effected so precisely on the base surface that the
arrange-
ment of the secondary color areas constitutes per se a security feature which
is com-
bined with the tilt effect caused by the embossed structure.
[0094] Fig. 29b shows the coating grid 7 from Fig. 29a in a variant. A
colorless
area 39 has been inserted around the grid formed by the primitives 9. This
results in a
dependence of the arrangement of the primitives 13 on the white areas 39 and
the
primitives 9. The resulting spatial dependence of the primitives 9 on
primitives of
other grids and the inserted areas 39 yields an additional security feature of
the coat-
ing 7.
[0095] Fig. 29c shows a further variant of a coating grid 7 with secondary
color ef-
fects. In this case, an area 38 has been inserted around the grid formed from
the
primitives 8, leading to a subdivision of the grids formed from the primitives
9 and
13. The spatial dependence of the primitives on the primitives of other grids
is an ad-
ditional security feature that cannot be readily imitated at present. In
addition, coating
7 of Fig. 29c yields overlap areas with secondary colors which lead to viewing
direc-
tion-dependent tilt effects by arrangement of an embossed structure.
Example 8 (Figures 30 to 34)
[0096] The inventive coating 7 shown in Fig. 30 consists of elliptical
primitives 8,
9 and 13 of different color. Unlike the hitherto described coatings 7, a
direction 47 is
marked that does not correspond to a preferred direction of the coating grid.
If the
arrangement of the linear embossed elements is effected along said direction,
a tilt
effect results from viewing directions that do not match the preferred
directions of the
coating grid. If the coating 7 with an embossed structure disposed in
direction 47 is
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integrated into a further coating 7 wherein the embossing is effected along
one of the
preferred directions of the coating 7, the depicted area of Fig. 30
constitutes addi-
tional information within the total coating.
100971 Figures 31, 32 show cross sections of embossed structures in which addi-
tional information 40 is contained. In the case of the structure shown in Fig.
31, the
additional information 40 is produced by a change of the grid spacing of the
em-
bossed grid. However, the additional information in the embossed structure of
Fig. 32
results from a change of the cross section of the linear embossed elements
from circu-
lar to triangular. [0098] The additional information of the coating can also
be easily disposed in an
embossed structure formed therefor, as is evident from the example of the
structure of
Fig. 33. The embossed structure comprising a triangular cross section has
amplitudes
20 and a comparatively large grid spacing, leaving between the single linear
em-
bossed elements base areas 31 that can be provided with the additional
infonnation of
the coating. The additional information incorporated there is visible in a top
view and
from certain viewing directions and shows a tilt effect inherent in the
inventive opti-
cally variable structure.
100991 Fig. 34 shows different cross sections of linear embossed elements. It
should be noted that cross sections involving a combination of the shown cross
sec-
tions are also possible. Also, the flanks of the cross section, e.g. those of
Fig. 34m,
can be concave.
Example 9 (Figures 35a, 35b, 36a and 36b)
[0100] The production of an inventive data carrier is explained in Figures
35a, 35b
and 36a, 36b.
[0101] The optically variable element is preferably produced by printing
technol-
ogy. For this purpose, the coating is printed on'a substrate, preferably the
document
CA 02642330 2008-08-13
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material, by any printing process, preferably offset printing, and said
coating is then
embossed accordingly with an embossing tool. The embossing tool preferably
used is
an intaglio printing plate. This procedure is shown in Figures 35a and 35b.
[0102] Fig. 35a shows an inventive data carrier in cross section before the
emboss-
ing process. The data carrier substrate 10 is first printed e.g. all over with
a base sur-
face layer 29. The coating comprising primitives 26, 27 is applied thereabove.
[0103] The base surface layer 29 can also be present in the form of
infonnation and
patterns. It is also possible to use special printing inks which further
increase the anti-
forgery effect of the optically variable element. These may be optically
variable print-
ing inks, such as printing inks containing interference layer pigments or
liquid crystal
pigments, or metallic effect inks, such as gold or silver effect inks.
[0104] Fig. 35b shows a sectional view of the data carrier after embossing,
which
has been done in the shown example as a blind embossing by intaglio printing.
The
embossing is so positioned that the coating with primitives 26, 27 comes to
lie on the
flanks of the embossed structure. Alternatively, the base surface 29 can also
be ap-
plied by another method, for example a transfer method, all over or likewise
provided
with gaps or a pattern. It is also possible to apply metallic pattern elements
or coat-
ings by the transfer method.
[01051 The base surface layer 29 can also be completely omitted, as shown in
Fig.
36a. However, the embossing, which is produced for example by steel intaglio
print-
ing, is executed with ink.
[0106] Fig. 36a shows the structure before embossing with substrate 10 and
coat-
ing 26, 27. Fig. 36b shows the situation after embossing. The structure shown
in Fig.
36b has been embossed with ink, so that an ink layer 30 is present congruently
with
the embossing. The additional ink layer 30 comes to lie as the uppermost
layer, since
this embossing has been carried out as the last method step here.
CA 02642330 2008-08-13
-36-
[0107] Preferably, an at least translucent ink is used for the ink layer 30.
The inta-
glio printing with ink can, in a variation, be so executed that inking is
effected only
on the nonlinear embossed elements, while the valleys between the nonlinear em-
bossed elements remain free of ink.
[0108] In a development, an ink with machine-readable additives, such as
lumines-
cent substances, can be used for the ink layer 30.
