Note: Descriptions are shown in the official language in which they were submitted.
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TRANSLATION
Security feature for a security document or
document of value with a fractal laminate system
The invention relates to a security feature for security documents and
documents of value
according to the generic term of patent claim 1 as well as to a process for
its production
State of the art in the arrangement of security features in the case of
security documents and
documents of value are so-called multiplex holograms. It is a matter here of a
hologram which
from different viewing directions generates different images for the viewer.
Further there are
known so-called interference layers in foils or generally in transparent
bodies. In such interference
layers it is a matter of thin optical layers which generate angle-dependent
graphic or color
effects--according to the viewing angle.
Further, so-called variable displays are known; here it is a matter of lens
arrays which can be
arranged on a security document over print or security features and according
to viewing direction
generate on these lenses a different image depending on the viewing angle.
The disadvantages of the techniques mentioned are that holograms and
interference layers can be
represented only poorly under multifarious conditions of illumination.
Furthermore, holograms
and interference layers are wave-dispersive: i.e., here in the viewing there
occur different color
fringes in white light, depending on the viewing angle.
The aforementioned lens arrays require complicated production techniques and a
certain, finite
substrate thickness.
U.S. 3,887,742 shows a security feature for a document of value, namely a
copying protection,
which consists of a transparent foil, and within this foil there are provided
obliquely arranged
lamellae. These lamellae are made black or reflecting, and bring it about that
information located
underneath the security feature can be read out and in the other direction
this information is not
visible for the viewer. In this other direction the observer receives the
graphic information of
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the lamellae, namely transmitted black or reflecting.
DE 25 40 846 A1 shows a protective coating for documents against copying in
the form of a
transparent film in which black lamellae are arranged obliquely.
A disadvantage of the forms of execution of the documents US 3,887,742 and DE
25 40 846 Al
is that only a slight resolution is achieved and a relative great swing angle
must first be run
through in order to obtain an information change from "not see-through" to
"see-through" . These
lamella structures, therefore, are only inadequately suited for the rapid and
sure checking of
security documents and documents of value, since they have a low resolution,
and a relatively
great swing angle has to be gone through, so that there is involved a time-
consuming checking of
the security documents and documents of value.
Underlying the invention, therefore, is the problem of further developing a
security feature of the
type mentioned at the outset so that under different viewing angles different
graphic
information data can be generated in a simpler and more economical manner.
For the solution of the problem posed the invention is characterized by the
technical teaching of
claim 1. 1
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For the solution of the problem posed, the invention is characterized by the
technical teaching of
claim 1.
An essential feature of the invention is that in a transparent body there are
arranged lamellae
nearly overlapping one another, which, increasing about stepwise, fill out the
cross section of the
body. Fractally increasing lamellae are preferred.
Underlying the invention, therefore, is the insight that a transparent
substrate is subdivided by a
nontransparent laminate system, and namely in such manner that the substrate
appears transparent
with a certain viewing direction upon the substrate, while, if the viewing
direction is changed, the
nontransparent laminate system becomes visible and prevents a looking through
the substrate.
If, with unchanging viewing direction the substrate is rotated under the eye,
the substrate appears
transparent or black according to the turning, because in the case of
blackening the nontransparent
laminate system with its non-transparent lamellae, prevents a view through the
substrate.
According to the turning of the substrate, therefore, a light-and-dark effect
is generated.
In a further development of the invention it is provided that not every
lamella forms a straight line
on its side edge, but each lamella is divided into a large number of part-
lamellae increasing in step
form one after another, so that, therefore, fractal lamellae are created,
which fill the cross section
of the substrate.
With the subdivision of the laminate system into fractal lamellae there is
yielded, namely, the
advantage that the switchover of the light-dark principle (look-through vs.
black) occurs abruptly;
i.e. if the lamellae are released with a correspondingly high iteration stage,
it is therewith ensured
that in a rotation of this substrate an abrupt switchover from light to dark
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occurs--i.e. from one graphic element to another. In the ideal state,
therefore, there are no
intermediate stages when a sufficiently high iteration stage occurs in the
resolving of individual
lamellae into fractal sub-lamellae.
In the above it was indicated that with the arrangement of fractal lamellae
such a transparent
substrate can be of such nature that during a total observation value of a
certain observation angle
of, for example 90° it appears fully transparent, and that then a
sudden switchover occurs and from
this switchover angle onward the substrate in further turning no longer
appears
transparent.
There is, therefore, for example, in the ideal case an angle from 0° to
90° where the substrate
appears transparent, while at an angle of from 91° to 180° the
substrate still appears only dark.
In a further development of the technical teaching according to the present
invention it is provided
that in such a transparent substrate there is present not only a single
laminate system which ensures
this light-to-dark switchover and therewith is in a position to deliver this
light-dark information,
but that in this substrate there are present several laminate systems which
cooperate.
As was stated earlier there is a range from 0° to 90° where the
first laminate system is transparent.
If one now arranges a second laminate system in the substrate so that in this
range--where the first
laminate system appears open and transparent, the second system appears
nontransparent, then
over this viewing angle from 0° to 90° there can be represented
altogether two different graphic
informations, namely the graphic information of the first laminate system
(which is bright) and in
which in this bright state the graphic information of the second laminate
system appears dark when
one looks through the substrate with the viewing angle from 0° to
90° remaining constant.
These laminate systems can be arranged next to one another and/or over one
another. They can
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cover each other, or be present in separate zones.
Above it was merely stated that light-and-dark graphics can be generated when
it is possible to
subdivide a linear lamella into individual fractally subdivided individual
lamellae. It is
obvious that with the present invention not only light-and-dark informations
can be conveyed, but
it can be provided that instead of the subdivision of a single linear line
course (single lamella) there
can also be fractally subdivided a letter consisting of individual line
strokes. This leads now to the
result that at a first viewing angle there becomes visible the substrate
transparent per se, for
example, of the letter A in the interior of this substrate and that with
increasing rotation of the
substrate into another viewing angle the letter A abruptly disappears and the
letter B pops up.
This is achieved exclusively by the overlapping and by the integration of two
different laminate
systems in the transparent substrate.
The laminate system of the invention is suited for use in transmitted light
and/or incident light.
The object of the present invention is yielded not only from the object of the
individual patent
claims, but also from the combination of the individual patent claims among
one another.
All the indications and features disclosed in the documents, inclusive of the
abstract, especially
the spatial construction represented in the drawings, are claimed as essential
to the invention
insofar as they are novel individually or in combination with respect to the
state of the art.
In the following the invention is explained in detail on the basis of drawings
which represent only
one course of execution. Here there proceed from the drawings and their
description further
features essential to the invention and further advantages of the invention.
In the drawings:
Fig. 1 shows schematically a substrate with a simple laminate arrangement with
non-fractal
subdivision;
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Fig. 2 a substrate modified with respect to Fig. 1, with a fractal subdivision
of lamellae;
Fig. 3a the representation of a continuous linear segment which forms the side
edge of a
lamella according to Fig. l:
Fig. 3b: the subdivision of a continuous linear segment which forms the side
edge of a
lamella according to Fig. 1;
Fig. 3c: the subdivision of the linear strokes according to Fig. 3b under
doubling of this
angle;
Fig. 3d: the subdivision of the linear course according to Fig.3c under
tripling of the angle;
Fig. 4: in schematized form a representation of the light-to-dark switchover
on change of
the viewing direction.
Fig. 1 shows a substrate, i.e., therefore, a transparent body 2 which shows
altogether three
lamellae 6, 7, 8 (arranged crudely with spacing next to one another). The body
has here two
lengthwise sides 3 spaced from one another and at a 90* angle from these there
are arranged here
the narrow sides 26. The body is further defined by an upper cover surface 4
and a lower cover
surface 5. It is a matter, therefore of a body 2 of about plate form, which is
to be transparent.
In the interior of the body there are now arranged lamellae 6, 7, 8 parallel
to one another, which
form between them interspaces 12, 13.
Each lamella is defined by a lengthwise edge 9, which runs about parallel to
the lengthwise edge
of the narrow sides 26, and otherwise the surface of each lamella 6 to 8 also
runs parallel to the
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narrow sides 26 of this plate-form body. The narrow sides of each lamella are
defined in each
case by a line segment 1, which runs about parallel to the narrow sides of the
body.
If one looks now through this transparent body in arrow direction 10, then one
sees through the
interspaces 12 between the lamellae 6, 7, 8, because the lamellae themselves
are not visible in this
direction and the body appears transparent.
If, however, one looks at the body 2 in arrow direction 11 (or in opposite
direction to this), then
the non-transparent lamellae 6, 7, 8 prevent a viewing through the body: the
body appears block.
In correspondence to the viewing direction, therefore, a light-and-dark
information can be
transmitted which depends on the position of the lamellae and the number of
them, etc.
If one now subdivides a line segment 1 according to Fig. 3 into several line
segments lb according
to Fig. 3b, then this line segment 1 is transformed.
Underlying the invention is the insight that with (fractal) lamella systems
surprising projection
properties can be realized. A fractal lamella system (laminate system) arises
through the repeated
application of a transformation onto a line segment 1. As an example, Fig. 3a
shows a laminate
system which arises through repeated division of a line segment 1 into N parts
and rotation about
an angle 8. Figs. 3b to 3d show different iteration stages of the
construction. Despite the ever
finer-becoming subdivision of the lamellae, the depth (D) required for the
laminate system
does not increase significantly. The laminate system from Fig. 3d is very
nearly impermeable to
light for all angles between 0° and +90° and is permeable to
light for all angles between 0°
and -90° (see Fig. 4). For a small angle 8 and a large N the deviations
from "impermeable to
light" and "permeable to light" with increasing iteration degree approach
zero. From such fractal
lamellae there can be constructed images which appear and disappear at sharply
defined angles.
It is mathematically proven that fractal laminate systems can be constructed,
the parallel
projection of which from every spatial angles yields a desired image for this
spatial angle.
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The laminate systems can be exposed, inscribed, imprinted, extruded,
mechanically generated
(bored) into a substrate or be realized in similar processes. They can be
designed for observation
in transillumination or incident illumination (rear side illumination or
reflection). By suitable
choice of the colors of substrate and lamellae the security feature can be
executed in color.
Advantages of the invention over the state of the art:
- Astonishing, clearly verifiable effect.
- the "reading-out" of the structure of the laminate system is very difficult.
- The resetting of the laminate system is still more difficult.
In a further development of the present invention it is provided that several
layers of such laminate
systems are present in panes of different depth of the substrate, and likewise
it
is provided that the angle-dependent graphic effect is visible in the
transmitted light.
Likewise in can be provided in another form of execution that the angle-
dependent graphic effect
is visible in incident light.
Fig. 2 shows the application of the fractal lamellae 14, 15, 16, 17 in a
substrate according to
Fig. 2.
There it is perceptible that the lamellae 14-17, with formation of interspaces
12, 13 are arrayed
tightly and stagewise as well as in step form on one another, in which
arrangement the interspaces
12, 13 permit a viewing through these fractal lamellae when the body 2 is
viewed from above in
the zone between the arrow directions 11-22, in contrast, the body 2 appears
dark.
In Fig. 3b it is further explained that the angle that is provided with
reference symbols 18,. and
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the angle 19 according to Fig. 3c is doubled with respect to the angle 18,
where, however, the
angle 20 in Fig. 3d is tripled with respect to the angle 18.
In Fig. 4 it is schematically represented that, in dependence on the viewing
direction 23, there is
a light zone 24 in the angle range from +90° to 0°, and likewise
a dark zone 25 in the angular
range from 0° to +90°.
With the given technical principle, therefore, security features can very well
be produced secure
against falsification, for such security features can very easily be
integrated into security
documents and value documents. Such a transparent body can be arranged in a
window-type
cutout of such a security document and value document and can be viewed either
in transmitted
or in incident light.
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Legends for drawings 1
1. Line segment 16
2. Body
3. Lengthwise side
4. Cover surface
5. Cover surface
6. Lamella
7. Lamella
8. Lamella
9. Longitudinal edge
10. Arrow direction (illumination direction)
11. Arrow direction (dark zone)
12. Interspace
13. Interspace
14. Fractallamella
15. Fractallamella
16. Fractallamella
17. Fractallamella
18. Angle
19. Angle
20. Angle
21. Arrow direction (light (or bright) zone)
22. Arrow direction (switchover (or transition) zone)
23. Viewing direction
24. Light (or bright) zone
25. Dark zone
26. Narrow side
