Note: Descriptions are shown in the official language in which they were submitted.
CA 02496829 2005-02-04
Data carrier with an optically variable element
This invention relates to a data carrier with an optically variable structure
having
an embossed structure with raised areas and a first coating contrasting with
the surface
of the data carrier, the embossed structure and the coating being so combined
that at
least parts of the coating are completely visible upon perpendicular viewing
but con-
cealed upon oblique viewing so that a tilt effect arises upon alternate
perpendicular
and oblique viewing. The invention further relates to a method for producing
such a
data carrier.
It has been known for some time to equip data carriers, such as bank notes, pa-
pers of value, credit cards or ID cards or the like, with optically variable
security ele-
ments, in particular optically variable diffraction structures such as
holograms. Protec-
tion from forgery by holograms is based on the different optical impression of
said
holograms that occurs upon a change of viewing angle relative to the hologram.
Said
optically variable impression cannot be rendered by copying machines since
copying
machines only render the appearance of the hologram from a certain viewing
angle. A
data carrier with such a hologram is known for example from EP 0 440 045 A2.
This
print proposes applying the hologram to the data carrier as a prefabricated
element or
as an embossing in a lacquer layer applied to the data carrier.
However, there are other optically variable security elements that can be pro-
vided on a data carrier. Thus, it is known for example from CA 1 019 012 to
provide a
bank note in a partial area of its surface with a parallel printed line
pattern. To produce
the optically variable effect, a line structure is additionally embossed into
the data car-
rier in the area of the printed line pattern so as to form flanks visible only
at certain
viewing angles. Selectively disposing the printed line pattern on like-
oriented flanks of
the embossed line structure causes the line pattern to be visible upon oblique
viewing
of the flanks provided with the lines. Upon oblique viewing of the rear side
of the
flanks the line pattern is not recognizable.
The antiforgery effect of such embossed optically variable security elements
can
be improved further if additional visually recognizable effects are produced
by selec-
CA 02496829 2010-10-14
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tively changing the line pattern or embossed structure. Examples of such
additional
effects are described in WO 97/17211 and WO 02/20280.
The optically variable effect of the latter known security elements arises
funda-
mentally from the combination of a print with a blind embossing that is
preferably
produced by intaglio printing. Blind embossing has the disadvantage that it
cannot be
integrated into a colored intaglio image but can only be used as an isolated
security
feature. This is because a relatively great distance between the blind
embossing areas
and the ink-carrying areas is required to make sure that absolutely no ink
gets into the
blind embossing depressions when the intaglio printing plate is inked.
The invention is therefore based on the problem of proposing a data carrier
with
an optically variable security element of the abovementioned kind that can be
inte-
grated into a printed image.
According to one aspect of the present disclosure, a data carrier with an
optically
variable structure is provided. The optically variable structures has an
embossed struc-
ture with raised areas and a first coating contrasting with the surface of the
data carrier
and provided only in certain areas, the embossed structure and the coating are
so com-
bined that at least parts of the coating are completely visible upon
perpendicular view-
ing but concealed upon oblique viewing so that a tilt effect arises upon
alternate per-
pendicular and oblique viewing. The optically variable structure has, at least
in partial
areas, a second coating disposed in overlap with the first coating at least in
partial
areas, such that the second coating likewise contrasts with the data carrier
surface. At
least one of the coatings consists at least partly of translucent inks.
According to another aspect of the present disclosure, a method for producing
a
data carrier with an optically variable structure is provided. The optically
variable
structure has an embossed structure with raised areas and a first coating
contrasting
with the surface of the data carrier and applied to the data carrier only in
certain areas.
The embossed structure and the coating are so combined that at least parts of
the coat-
ing are completely visible upon perpendicular viewing but concealing upon
oblique
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viewing so that a tilt effect arises upon alternate perpendicular and oblique
viewing.
The method includes applying the first coating to the data carrier only in
certain areas
and embossing the embossed structure in the data carrier by means of an
embossing
tool. With the embossing, a second coating is transferred to the data carrier
in overlap
with the first coating at least in partial areas. Accordingly, a color
likewise contrast-
ing with the surface of the data carrier is selected for the second coating
and the trans-
ferring of the second coating to the data carrier is done congruently to at
least parts of
the raised areas of the embossed structure. At least one of the coatings
consists at least
partly of translucent inks.
The invention is based on the finding that the optically variable effect of
the se-
curity element is retained if an ink-carrying embossing is used instead of the
blind em-
bossing. That is, the optically variable structure has at least in partial
areas a second
coating likewise contrasting with the data carrier surface and disposed
congruent to the
raised areas of the embossed structure. The second coating offers the
advantage of sta-
bilizing the embossed structure without an additional printing operation.
Moreover, the inventive security element has the advantage that it can be inte-
grated into an intaglio motif and thus into the representational and color
design of the
main motif.
Intaglio printing is characterized in that linear depressions are provided in
the
printing plates to produce a printed image. Areal representations are also
produced by
closely adjacent engraved lines, the individual engraved lines normally being
fractions
of a millimeter wide.
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For the printing operation the engraved lines of the plate are filled with
ink. Sur-
plus ink is removed from the plate with the help of a wiping cylinder or
doctor blade
such that the engraved lines are filled with ink up to the edge. During the
printing op-
eration the data carrier to be printed, normally paper, is finally pressed
onto the plate
with high pressure by means of a pressure cylinder having an elastic surface.
The data
carrier is thereby pressed into the ink-filled engraved lines of the plate,
thus coming in
contact with the ink. When the data carrier is detached it pulls the ink out
of the de-
pressions of the engraved lines. The thus produced printed image has printed
lines that
vary in ink layer thickness depending on the depth of engraving. The data
carrier is
pressed into the depressions of the plate so strongly that it not only
receives ink from
Q the depressions but is also simultaneously embossed.
When translucent inks are used in intaglio printing, light color tones are
obtained
if a white data carrier is printed with thin ink layers, and darker color
tones if printed
with thick ink layers. This effect can also be utilized within the scope of
the invention
to produce different color effects and increase the contrast of the tilt
effect. Likewise,
it is possible to combine translucent and nontranslucent inks.
The inventive optically variable structure can therefore be integrated into
the
printing plate of an intaglio motif in a very simple way by providing the
embossed
structure likewise in the form of depressions in the plate. During the
printing operation
0 the depressions belonging to the embossed structure are filled with an ink
having for
example the same color as the intaglio motif to be printed. This ink layer,
which is
transferred to the data carrier with the embossing operation, forms the
inventive sec-
ond coating disposed congruent to the raised areas of the embossed structure.
It is not necessary for the total embossed structure to be inked with this
color.
Only partial areas of the embossed structure can also be provided with a
color. Alter-
natively, it is also possible to provide the embossed structure with different
colors or a
color flow. Such a color flow can be produced via a color split whereby the
printing
plate is accordingly inked by means of single color stencils. Preferably, the
color of the
second coating is integrated into the color design of the intaglio motif.
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The color split and a corresponding choice of printing inks employed are used
se-
lectively here to control the contrast of the optically variable structure.
The color split can also be used to make parts of the optically variable
structure
machine-readable by adding at least one feature substance, such as a
luminescent sub-
stance, magnetic substance or electrically conductive substance, to at least
one of the
inks. Different parts of the optically variable structure can also be provided
with dif-
ferent feature substances. Alternatively, the total optically variable
structure can also
be equipped with a uniform machine-readable property.
The optically variable structure can be directly adjacent to the intaglio
motif or
else be part of the steel intaglio motif.
Since such intaglio motifs are primarily applied in security printing, the
inventive
data carrier is preferably a paper of value, in particular a bank note. The
paper of value
can be a security paper made of cotton fibers, a paper containing synthetic
fibers
and/or chemical pulp, or consist of pure plastic foils. Such a paper of value
can also be
used advantageously for protecting any products and goods.
The second coating disposed in the area of the embossed structure can moreover
have a color contrasting with the first coating and be disposed at least in
partial over-
lap with the first coating. Further, one of the coatings can have machine-
readable
properties at least in certain areas. These may be for example magnetic,
electrically
conductive or luminescent properties. Finally, the data carrier can have a
metallic
background layer in the area of the optically variable structure.
The embossed structure is preferably executed as a screen structure. It can be
tri-
angular, but also trapezoidal, sinusoidal, semicircular or another shape.
Preferably, the
embossed structure is executed as a line screen with a constant screen ruling.
In some
embodiments, however, it can also be expedient to use different screen
rulings. For
example, the screen ruling can increase continuously in the edge area of the
optically
variable structure so that the embossed structure quasi tapers out. The same
effect can
be obtained by a continuous reduction of line width with constant or
increasing screen
CA 02496829 2010-10-14
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ruling. In this edge area the first coating can be adapted in accordance with
the em-
bossed structure or be completely lacking.
Further effects can be obtained if the flank angles vary within a line of the
em-
bossed structure executed as a line screen.
To better bring out the optically variable effects, the embossed structure can
be
subdivided into partial areas where different partial embossed structures are
provided,
as described in WO 02/20280.
The partial areas preferably form a two-dimensional matrix having m partial
areas in the horizontal direction and n partial areas in the vertical
direction, where in, n
> 1, preferably m, n > 2. The partial embossed structures in at least two
adjoining par-
tial areas are disposed mutually offset by a fraction, in particular one
third, of the
screen ruling.
The first coating is preferably a print likewise formed as a screen structure,
whe-
reby the individual screen elements can be designed at will. However, a line
screen
with a constant screen ruling is preferably used. According to a preferred
embodiment,
said line screen consists of printed lines of any desired color design. The
print is done
by any desired printing process, such as offset or screen printing. Any
desired indirect
printing processes, such as indirect letterpress, can also be applied. The
methods
moreover make it possible to provide the first coating with a color flow, a so-
called
"rainbow blend."
Printed screen and embossed structure are adjusted to each other, preferably
such
that the width of the printed screen lines is somewhat smaller than the length
of the
flanks of the embossed structure lines and that they extend parallel or
largely parallel.
Printed screen and embossed structure need not necessarily extend in a
straight line,
they can instead also be designed in the form of wavy lines, etc. The line
widths are
between 25 microns and 300 microns, preferably between 55 microns and 150
micro-
ns. If the line screen is composed of printed, spaced-apart lines, a ratio of
about 1 :1 is
preferably selected for the ratio of printed to unprinted areas. If a line
width in the
CA 02496829 2005-02-04
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order of magnitude of about 100 microns is additionally selected, the lines
can virtu-
ally no longer be resolved by the eye and a homogeneous color effect arises.
That is,
the line screen is visually perceived only as a homogeneous colored surface.
Addition-
ally, the lines can be executed thicker in certain areas and thus represent
for example a
halftone image or another motif. Preferably, the lines only have thickened
areas on one
side. This likewise leads to stronger contrast. Alternatively, the lines can
have gaps to
produce an additional visually recognizable pattern. The first coating and/or
the em-
bossed structure can also be executed so as to repeat the content of other
information
present on the document of value to make comparison possible.
Quite generally it is to be underlined that the color design of the security
element
can be adjusted at will by a corresponding color choice of first and second
coatings,
since the mixture of the two colors is always perceived at least in a top
view. Likewise,
the information perceptible from different viewing angles can be adjusted by a
corre-
sponding choice of parameters, such as color, line thickness and line
modulation of the
first coating and flank angle, flank height and flank modulation of the
embossed struc-
ture.
Rasterization of the print can be dispensed with if optically variable inks
are
used, i.e. inks having different optical effects dependent on the angle of
vision. These
may be high-gloss, e.g. metallic, layers or else inks that change their color
effect them-
selves in angle-dependent fashion, as is the case for example with liquid
crystal pig-
ment inks.
However, an inventive optically variable structure with a rasterized first
coating
can also be additionally underlaid or covered with an optically variable
printed image.
This is preferably done with printing inks having interference layer and/or
liquid crys-
tal pigments. An additional metallic background is also conceivable. The
printed im-
age can be executed to be positive or negative. The use of liquid crystals
additionally
provides elevated protection from forgery since the printed image in this case
has
light-polarizing properties that can be read by machine. This holds in
particular when
the printed image is composed of partial printed images, with liquid crystals
having
different polarization properties being used for the partial printed images.
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The inventive optically variable structure can be underlaid or covered, not
with
an additional printed image, but with a foil element, such as a diffraction
structure em-
bossed into a lacquer layer. Here, any desired layer structures and types of
foil ele-
ments can be used, such as real holograms, lattice structures, volume
holograms that
are executed to be transparent, semitransparent or opaque.
According to a preferred embodiment, the inventive optically variable
structure
consists of a print in the form of a printed line screen, a first color and an
embossed
structure superimposed on said line screen and likewise executed in linear
fashion
whose raised areas are provided with a further color contrasting with said
first color.
Said second color is preferably produced by means of translucent printing inks
that
have a certain transparency so that the color of the first coating shines
through said
color and the viewer thus perceives a mixed color in the superimposed areas.
Espe-
cially good effects are achieved if there is a complementary contrast between
the first
and second colors.
When viewing said optically variable structure perpendicular to the data
carrier
surface, the viewer ideally recognizes only a uniform color effect. When the
data car-
rier is tilted or the viewing angle changed, parts of the first and/or second
coating are
concealed by the embossed structure, so that in certain areas the color effect
of the first
or second coating or of the mixed color of the two coatings predominates and
thus
variable color effects arise.
This interplay of colors appears all the more clearly the better-contrasting
the
colors of the two coatings are. For example, a dark, e.g. black, line screen
can be com-
bined with a well-contrasting colored intaglio print with translucent inks,
such as yel-
low or other light color tones. The first coating in the form of a black line
screen is
preferably printed on here by the offset process.
Alternatively, a further preferably all-over ink layer can be disposed under
the
first preferably screenlike coating. Said layer serves to stabilize the paper
in the area of
the security element and permits sharper edges in the area of the embossed
structure.
Said layer can be executed as a primer or colored lacquer layer or else
contribute addi-
tionally to the color design of the security element if said layer has a color
contrasting
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with the first coating. One can use conventional printing inks or else special-
effect
inks, such as luminescent inks or printing inks containing interference or
liquid crystal
pigments.
Finally, additional information can also be incorporated by designing the em-
bossed structure and/or first coating accordingly. For example, the raised
areas of the
embossed structure can have different heights. If the embossed structure is
produced
by intaglio printing, this means that the engraving depths for the embossed
structure
are selected differently. The areas of lower engraving depth are filled with
less ink in
the printing or embossing operation and produce areas with a lighter color
tone if
translucent inks are used. In this way the inventive second coating can be
used to pro-
duce additional information visually recognizable at all viewing angles. Due
to the
different embossing heights, however, a change of viewing angle yields
additional op-
tically variable effects that are caused by the relative position of the first
and second
coatings as well as the embossed structure and the interplay thereof.
The additional information can also be emphasized by an unembossed edge con-
tour, as already described in WO 02/20280. Alternatively, the edge contour can
also be
provided with the second coating and the embossed structure according to the
inven-
tion.
As mentioned above several times, the inventive optically variable security
ele-
k 0- is preferably produced in two printing operations. In a first printing
operation,
preferably by the offset process or an indirect printing process, the first
coating is
printed on the data carrier. In the second printing operation, which is
preferably done
by intaglio according to the invention, the embossed structure and the second
coating
are finally transferred to the data carrier simultaneously.
Similar optical effects can be achieved if the two coatings are printed on in
regis-
ter to each other by offset and/or screen printing and this printed area is
then provided
with a blind embossing likewise in register. All embodiments described within
the
scope of the invention can be produced in this way. According to a special
embodi-
ment, for example, a line screen in a first color can be applied and at least
partly in
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overlap therewith a second coating of translucent inks all over. In a last
step, the total
printed area is provided with a blind embossing in the form of a line screen
in register.
However, it is also possible to use the reverse order, providing first the
embossed
structure and second coating on the data carrier and then the first coating.
Further embodiments and advantages of the invention will be explained with ref-
erence to the figures, in which:
Fig. 1 shows an inventive data carrier,
Fig. 2 shows a section along A - A in Fig. 1,
Fig. 3 shows a schematic representation of the relative position between the
first
and second coatings of the inventive security element in a first embodiment,
Fig. 4 shows a schematic representation of the relative position between the
first
and second coatings of the inventive security element according to a second
embodi-
ment,
Fig. 5 shows a schematic representation of the relative position of the first
and
second coatings of the inventive security element according to a third
embodiment, the
embossed structure having raised areas of different heights,
Fig. 6 shows an inventive embossing mold in cross section for producing the em-
bossed structure with additional information,
Fig. 7. shows a further embodiment of the inventive embossing mold,
Fig. 8 shows a further variant of the inventive security element,
Fig. 9 shows a further variant of the inventive security element,
Fig. 10 shows a special embodiment of the inventive security element wherein
the embossed structure is present in the form of a matrix,
Fig. 1 I shows a special embodiment of the embossed structure of the inventive
security element.
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Fig. 1 shows inventive data carrier I with optically variable structure 2.
Optically
variable structure 2 is a security feature that can be checked without aids
and is used
optionally alongside further security features for checking the authenticity
of the data
carrier. The further security features may be for example a security thread,
watermark
or the like. As preferred within the scope of the invention, optically
variable structure
2 is disposed in the area of intaglio motif 3 of document of value 1. The
geometrical
and color design of optically variable security element 2 can be adapted to
intaglio
motif 3. Depending on the execution of intaglio motif 3, optically variable
structure 2
can also be integrated completely into said intaglio motif.
However, the inventive security element can alternatively be disposed at any
other place on document of value 1.
It is especially advantageous to use inventive optically variable structure 2
in
bank notes, as well as other papers of value such as shares, checks or the
like. Labels
or other elements for product protection can also be provided with such an
optically
variable structure.
Optically variable structure 2 consists according to the shown embodiment of a
first coating in the form of a print contrasting with the surface of the data
carrier as
well as an embossed structure and a second coating that likewise contrasts in
color
with the data carrier surface and is disposed congruent to the raised areas of
the em-
bossed structure. The various elements of optically variable structure 2 are
combined
with each other such that at least partial areas of the first coating are
completely visible
upon perpendicular viewing but concealed upon oblique viewing.
This principle is made clear by the section along A - A shown in Fig. 2. First
coating 4 consists of line screen 4, in the case shown here, and embossed
structure 5 is
also designed in the form of a line screen structure. Second ink layer 6 is
disposed
congruent to embossed structure 5, thus completely covering first coating 4.
Upon per-
pendicular viewing from viewing direction A, the viewer ideally recognizes
only a
colored surface whose color largely corresponds to the mixed color of first
coating 4
and second coating 6. Upon oblique viewing from viewing direction B, the
viewer is
faced by the flank of embossed structure 5 that coincides with the printed
lines of
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printed screen 4. The viewer therefore perceives from viewing direction B an
almost
uniform colored print in the color of the mixed color from first coating 4 and
second
coating 6. In viewing direction C the viewer is faced by the flanks of
embossed struc-
ture 5 that coincide with the particular gap of line screen 4, so that from
this direction
the viewer perceives a likewise uniformly colored surface in the color of
second coat-
ing 6.
Embossed structure 5 and second coating 6 are preferably transferred to docu-
ment of value 1 by the intaglio printing plate. This has the advantage that
the security
element can be produced simultaneously with intaglio motif 3 in one operation.
For
this purpose, both the negative of desired embossed structure 5 and the
intaglio motif
0 are engraved into the printing plate. During the printing operation the
printing plate is
filled with ink and then data carrier material 1 is pressed into the engraved
areas of the
plate and lastingly deformed. The high contact pressure causes embossing 5 to
also be
noticeable on the back of data carrier material 1.
The printing plate, can be inked with a uniform color for the printing
operation so
that second coating 6 and intaglio motif 3 have the same color. Different
colors can
also be used, however.
Since translucent inks are preferably used for second coating 6, the viewer
can
recognize the mixed color of the two colors in the overlap area between first
and sec-
AN and coatings 4, 6.
Embossed structure 5 shown in Fig. 2 consists of directly adjoining triangular
profiles when viewed in cross section. However, the triangular profiles can
also be
slightly spaced apart. The relative position of first coating 4 and second
coating 6 or
embossed structure 5 can also vary, as made clear by Figs. 3 to 5. Here, only
the em-
bossed profile and the relative position of coatings 4, 6 are shown.
In Fig. 3 the triangular profiles of embossed structure 5 are spaced apart,
which is
indicated by connection bars 7. First coating 4 is disposed on one of the
flanks of em-
bossed structure 5 below second coating 6, as shown in Fig. 2. Connection bars
7 are
coating-free, however, so that the data carrier surface is visible in this
area.
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Fig. 4 shows a variant in which first coating 4 completely covers connection
bars
7 and part of the flanks of embossed structure 5. In this example, second
coating 6
covers first coating 4 only partly, so that first coating 4 is also visible in
partial areas.
Fig. 5 shows a further embodiment in which the relative position of embossed
structure 5, first coating 4 and second coating 6 corresponds to the
embodiment al-
ready shown in Fig. 3. However, the raised areas of embossed structure 5 have
differ-
ent heights in this example. If embossed structure 5 and coating 6 are
produced by ink-
carrying intaglio printing, this means that more ink is transferred in the
areas of the
embossed structure with the higher raised areas. Due to the higher ink layer
thickness
in area 8 of embossing 5, partial areas 8 of embossing 5 appear in a darker
color tone
than partial areas 9 of embossing 5. In this way, additional information can
be pro-
duced in the optically variable element.
However, such visually recognizable additional information can also be
produced
in other ways. If translucent printing inks are used, the additional
information can also
be represented by a higher ink layer thickness in certain areas of the printed
image.
Fig. 6 shows in cross section printing plate 30 for producing such additional
in-
formation. First printed image 31 is engraved into plate 30 with depth t1.
Second
printed image 32, which is superimposed on first printed image 31, is engraved
into
plate 30 with depth t2. Since the engraving for second printed image 32 is
deeper than
the engraving for first printed image 31, more ink is transferred in the area
of printed
image 32. When translucent printing inks are used, a darker color effect
therefore re-
sults in the area of printed image 32, and printed image 32 is recognizable
against
lighter printed image 31. According to this example, the two printed images
31, 32
form the second coating that is transferred to the document of value
simultaneously
with the embossed structure in the printing operation.
Fig. 7 shows a further variant for producing additional information in the
second
coating. It again shows printing plate 30, into which a line with width b is
milled. Said
line is composed of different areas 33, 34 that differ in their depth and
flank steepness.
In the finished printed image said line shows different color effects along
its length
since the inking is different in areas 33, 34.
AMENDED SHEET
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If the line depth is too great, paper tears might occur during the embossing
opera-
tion. To therefore permit the same line width to be retained, it might
therefore be nec-
essary to make the line just as wide but less deep. If a milling tool is used
for produc-
ing the printing plate, it might therefore be necessary to produce the line by
means of a
narrower engraving tool that nevertheless produces the width of the desired
engraved
line by corresponding guidance of the milling tool.
Fig. 8 shows a further embodiment of the inventive optically variable
structure.
In this example, the first coating consists of two crosswise disposed line
screens 10, 11
that can also be designed in different colors. In the shown example, the lines
of printed
screen 11 are disposed on one of the flanks of embossed structure 5. This
association
emerges from the profile sketches at the lower edge of Fig. 8, which shows a
detail of
embossed structure 5 and coating 6 in cross section.
Fig. 9 shows an embodiment of the inventive optically variable structure in
which the first coating consists of one-sided screen 40. Said screen starts at
straight
baseline 41. Opposite line 42 of the screen element is of irregular design and
can vary
from screen element to screen element. This particular screen can be used to
represent
very well-contrasting halftone images. As explained above with reference to
Fig. 8,
said screen elements 40 preferably come to lie on the flanks of embossed
structure 5
and are covered by second coating 6.
Fig. 10 shows a top view of the basic structure of inventive optically
variable
structure 2. It consists of the first coating in the form of line screen 4
with a constant
screen ruling, the line screen consisting of spaced-apart printed lines.
Embossed struc-
ture 5 is disposed in overlap with print 4, being indicated only by the dash-
lined frame
for clarity's sake. Shown embossed structure 5 is subdivided into six partial
areas 50,
51, 52, 53, 54, 55 where partial embossed structures are disposed, being
omitted from
the drawing as mentioned above. The second coating, which is disposed
congruent to
the raised areas of the partial embossed structures, is not shown either.
Partial areas 50,
51, 52, 53, 54, 55 are directly adjacent here and form a two-dimensional
matrix. De-
pending on the embodiment, said matrix can have n partial areas in the
vertical direc-
tion and m partial areas in the horizontal direction, where n, m > 1,
preferably n, in > 2.
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In the shown example, n - 3 and m - 2. A second coating, which is likewise
omitted
from the drawing, is disposed congruent to the raised areas of embossed
structure 5 in
this example as well.
The relative position of the partial embossed structures and line screen 4
varies
within embossed structure 5 from partial area to partial area, so that partial
areas 50,
51, 52, 53, 54, 55 differ in their color, color tone or brightness and are
thus visually
recognizable as contrasting partial areas. Upon a change of viewing angle, the
color
and light/dark impressions of the partial areas vary. This impression is
strengthened by
superimposed second coating 6.
Fig. 11 schematically shows a further special embodiment of embossed structure
5. It is composed of partial areas 50, 51, 52, 53, 54, 55 where different
partial em-
bossed structures 20, 21, 22, 23, 24, 25 are disposed. The sloping lines in
Fig. 11 indi-
cate the course and arrangement of particular partial embossed structure 20,
21, 22, 23,
24, 25. The shown lines mark the valleys of the embossed structure, as is made
clear
by the sketch in the left area under embossed structure 5, which shows partial
em-
bossed structure 23 in cross section. For clarity's sake, the zeniths of
partial embossed
structures 20, 21, 22, 23, 24, 25 have not been shown with lines in the
figures.
All partial embossed structures 20, 21, 22, 23, 24, 25 have same screen ruling
a.
However, pairs of adjoining partial embossed structures 20, 21, 22, 23, 24, 25
are mu-
g
tually offset. In the shown example, the offset is preferably a fraction l/x
of screen
ruling a. Preferably, a pair of adjacent partial embossed structures is
mutually offset by
one third of screen ruling a. The first coating has been omitted in Fig. 11
for clarity's
sake. Since the arrangement of the partial embossed structures and congruently
dis-
posed second coating varies from partial area to partial area, however, the
relative po-
sition between the first coating and particular partial embossed screen 20,
21, 22, 23,
24, 25 also varies accordingly. This produces frequently changing light/dark
contrasts
and changing color effects that visually stand out clearly and are well
recognizable. If
the offset is selected for example so that the partial embossed structures
recur within
embossed structure 5, a plurality of partial areas show the same appearance
from one
viewing angle. However, partial embossed structures 20, 21, 22, 23, 24, 25 of
inven-
CA 02496829 2005-02-04
- 15-
tive embossed structure 5 need not be fundamentally offset by a fraction of
screen rul-
ing a. Any other offset is equally conceivable. Also, not all partial embossed
structures
20, 21, 22, 23, 24, 25 need be mutually offset. In some circumstances it is
sufficient if
only two of partial areas 50, 51, 52, 53, 54, 55 are provided with mutually
offset par-
tial embossed structures 20, 21, 22, 23, 24, 25. The latter also need not
necessarily be
directly adjacent. Likewise, single partial areas 50, 51, 52, 53, 54, 55 can
be provided
with partial embossed structures 20, 21, 22, 23, 24, 25 with different screen
ruling a.
The extending direction of single partial embossed structures 20, 21, 22, 23,
24, 25 can
also vary with respect to the extending direction of adjacent partial embossed
struc-
tures 20, 21, 22, 23, 24, 25. For example, partial embossed structure 20 can
be dis-
posed at an angle of 90 to partial embossed structure 21.
In the shown examples, the first coating was always applied first and then em-
bossing 5 or second coating 6. Alternatively, it is of course also possible to
first apply
the embossed structure and the second coating and then print the first coating
on the
second coating.
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