WO2022227741A1 - 光学防伪元件及其设计方法、防伪产品 - Google Patents
光学防伪元件及其设计方法、防伪产品 Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
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- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
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Definitions
- the present application relates to the technical field of anti-counterfeiting, in particular to an optical anti-counterfeiting element, a design method thereof, and an anti-counterfeiting product.
- optical anti-counterfeiting technology is widely used in various high-security or high-value-added products such as banknotes and financial instruments, and has achieved very good results.
- the eye-catching technology is the combination of the microstructure determined by the plate making and the optically variable layer, as disclosed in Chinese Patents CN 102712207 A and CN 107995894 A, by modulating the brightness distribution of the reflected light through the pre-designed micro-reflection surface, so as to realize Dynamic effect, and can superimpose interference coating to realize the combination of color change and dynamic effect.
- This often produces patterns, such as lines, rings, curves, or multiple motion effects of text, and can create a three-dimensional feel.
- the color tone of the pattern and the background can only be the same, and the light-dark contrast relationship is basically single, so it is difficult to realize the dynamic characteristics of multiple colors or any light-dark relationship.
- Demonstrations with three-dimensional depth effects can also be produced by Moiré magnification constructions based on microlenses and micropatterns, such as described in patent WO 2005/052650 A2.
- a periodic presentation composed of many small micropatterns is enlarged using a grid composed of microlenses with similar but not identical periods.
- the disadvantage of this moiré magnification configuration is that it is complex to manufacture, requiring two imprinting steps for the microlenses and micropatterns, with precise alignment between the two steps.
- magnetically aligned reflective pigments are aligned with correspondingly shaped magnets, resulting in a bright (especially annular) dynamic effect that can include a certain depth effect.
- This effect is very bright and easy to see, but the magnetic ink required is expensive, and the variety and resolution of the effect is limited by the available magnets, making it difficult to adjust at will.
- the purpose of the embodiments of the present application is to provide an optical anti-counterfeiting element, a design method thereof, and an anti-counterfeiting product, which have a simple manufacturing process and can flexibly realize dynamic features such as color and/or light-dark contrast.
- an embodiment of the present application provides an optical anti-counterfeiting element.
- the optical anti-counterfeiting element can present dynamic features.
- the dynamic features are pre-designed as a reproduction of a set of animation frames visible at a preset viewing angle set ⁇ v, and the animation frames include patterns.
- the optical anti-counterfeiting element has a roughly smooth diffusely reflective curved surface, and the incident light can be reflected by the diffusely reflective curved surface to form a roughly uniform within the range not less than the preset observation angle set ⁇ v Brightness distribution;
- the diffuse reflective surface includes a modified surface area and an undecorated surface area, and the modified surface area and the undecorated surface area have different reflection characteristics, wherein the modified surface area is similar to the pattern area.
- the diffusely reflective curved surface when the diffusely reflective curved surface is irradiated by incident light, the modified curved surface areas together appear as a pattern of dynamic features, and the unmodified surface areas together appear as a dynamic feature background.
- the diffusely reflective surface is periodic in at least one direction.
- the diffusely reflective surface is aperiodic in at least one direction.
- the average distance between adjacent wave crests and wave troughs of the diffusely reflective curved surface is 5 ⁇ m to 100 ⁇ m, preferably 10 ⁇ m to 30 ⁇ m.
- the average height difference between adjacent wave peaks and wave troughs of the diffusely reflective curved surface is 1 ⁇ m to 10 ⁇ m.
- At least a portion of the unmodified surface area is smooth or has secondary structures.
- the modified surface area is modified in one or more of the following ways: adding secondary structures to the modified surface area; smoothing the modified surface area; making the modified surface area flatten the area; set the modified surface area to be convex or concave compared to the unmodified surface area; adjust the angle of the modified surface area so that incident light is reflected beyond a preset set of viewing angles ⁇ v range; or adjust the thickness of the coating or coating of the modified surface area to be different from that of the unmodified surface area.
- the two or more ways exist in a parallel combination and/or a serial combination.
- the lateral feature size of the secondary structure is 0.2 ⁇ m to 5 ⁇ m.
- the different reflection characteristics refer to one or a combination of the modified curved surface area and the unmodified curved surface area having different reflection colors, different reflection brightness, or different reflection textures when irradiated by incident light.
- an embodiment of the present application also provides a design method for an optical anti-counterfeiting element, the design method includes: designing a dynamic feature, where the dynamic feature is the reproduction of a group of animation frames visible at a preset observation angle set ⁇ v, the animation frame It includes a pattern area and a background area that forms optical contrast with the pattern area; a generally smooth diffusely reflective curved surface designed for optical anti-counterfeiting elements, so that incident light can be reflected by the diffusely reflective curved surface at not less than the preset viewing angle set ⁇ v.
- a generally uniform brightness distribution is formed within the range; based on the observation angle of each animation frame of a group of animation frames, the area corresponding to the pattern area of each animation frame is modified to form a modified surface area, so that the modified surface area It has different reflection characteristics from the unmodified surface area.
- the modified surface area When the diffusely reflective surface is illuminated by incident light, the modified surface area together presents a dynamic feature pattern, and the unmodified surface area together presents a dynamic feature background.
- the diffusely reflective surface is periodic in at least one direction.
- the diffusely reflective surface is aperiodic in at least one direction.
- the average distance between adjacent wave crests and wave troughs of the diffusely reflective curved surface is 5 ⁇ m to 100 ⁇ m, preferably 10 ⁇ m to 30 ⁇ m.
- the average height difference between adjacent wave peaks and wave troughs of the diffusely reflective curved surface is 1 ⁇ m to 10 ⁇ m.
- modifying the area corresponding to the pattern area of each animation frame to form a modified surface area including: modifying each animation frame in a group of animation frames.
- the animation frame and the diffuse reflection surface are pixelated; the first azimuth angle and the first pitch angle of each animation frame are determined, and the first azimuth angle and the first pitch angle are determined according to the observation angle of the animation frame; the diffuse reflection surface is determined
- the second azimuth angle and the second pitch angle of each pixel of the At the position of the diffuse surface corresponding to the pixels of the pattern area in the animation frame, look for the second azimuth angle and the second pitch angle corresponding to the first azimuth angle and the first pitch angle of the animation frame. pixels, thereby forming an area corresponding to the pattern area of the animation frame in the diffuse reflective surface; and modifying the area corresponding to the pattern area of the animation frame formed in the diffuse reflective surface.
- a second azimuth angle and a second azimuth angle that match the first azimuth angle and the first pitch angle of the pixels in the pattern area at the positions of the diffuse reflective surface corresponding to the pixels of the pattern area in the animation frame.
- the pixels corresponding to the pitch angle include: within a preset distance range between the diffuse reflective surface and the pixels in the pattern area in the animation frame, searching for an angular difference with half the first azimuth angle within the first preset distance.
- the preset distance range refers to that the distance from the pixel position of the pattern area in the animation frame is less than 100 ⁇ m, preferably less than 50 ⁇ m; and/or the first preset angle difference range refers to the distance from the first azimuth angle. The angle difference between them is less than 3°, preferably less than 0.5°; and/or the second preset angle difference range means that the angle difference from the first pitch angle is less than 3°, preferably less than 0.5°.
- modifying the area corresponding to the pattern area of each animation frame to form a modified surface area includes performing one or more of the following manners: adding secondary structures to the modified surface area; Smooths the retouched surface area; flattens the retouched surface area; sets the retouched surface area to be convex or concave compared to the undecorated surface area; adjusts the angle of the retouched surface area , so that the incident light is reflected beyond the range of the preset observation angle set ⁇ v; or the thickness of the coating or coating of the modified curved surface area is adjusted to be different from that of the unmodified curved surface area.
- the dynamic feature is one or a combination of translation, rotation, scaling, deformation, looming, and yin-yang conversion; and/or the optical contrast is one or a combination of different colors, different brightness, and different textures visible to the human eye. .
- the width of the modified curved area is 0.5 ⁇ m to 20 ⁇ m, preferably 2 ⁇ m to 10 ⁇ m.
- the embodiments of the present application further provide an anti-counterfeiting product using the above-mentioned optical anti-counterfeiting element.
- an embodiment of the present application further provides a data carrier, where the data carrier has the above-mentioned optical anti-counterfeiting element, or has the above-mentioned anti-counterfeiting product.
- the optical anti-counterfeiting element provided by the embodiment of the present application has a simple manufacturing process and can flexibly realize dynamic features such as color and/or light-dark contrast.
- dynamic features such as color and/or light-dark contrast.
- various multi-color dynamic features can be displayed macroscopically, and there is no directly identifiable microscopic feature. Arrangement rules to enhance the difficulty of counterfeiting in multiple dimensions such as microstructure design and manufacturing process.
- 1 is a schematic diagram of the diffuse reflection effect of the diffusely reflective curved surface area of the optical anti-counterfeiting element on incident light;
- Fig. 2 is a kind of design example diagram of periodic diffuse reflection curved surface area
- Fig. 3 is a kind of design example diagram of aperiodic diffuse reflection curved surface area
- Fig. 4 is an embodiment of determining the curved surface area to be modified according to the animation frame
- FIG. 6 is a schematic diagram of a partial or overall modification method of the modified curved surface area
- FIG. 7 is a schematic diagram of the use of the optical anti-counterfeiting element on a banknote.
- the embodiments of the present application provide an optical anti-counterfeiting element.
- the optical anti-counterfeiting element can present dynamic features.
- the dynamic features are pre-designed as the reproduction of a set of animation frames visible at a preset viewing angle set ⁇ v, and the animation frames include a pattern area and a pattern area.
- the background area that forms the optical contrast; the optical anti-counterfeiting element has a roughly smooth diffusely reflective curved surface, and the incident light can be reflected by the diffusely reflective curved surface to form a roughly uniform brightness distribution within the range of not less than the preset observation angle set ⁇ v; diffuse reflection
- the characteristic surface includes a modified surface area and an undecorated surface area, and the modified surface area and the undecorated surface area have different reflection characteristics, wherein the modified surface area corresponds to the pattern area; in the diffuse reflection When the curved surface is irradiated by incident light, the modified surface area together presents a dynamic feature pattern, and the unmodified surface area together presents a dynamic feature background, that is, the modified reflective surface elements jointly reproduce the dynamic feature pattern. , the undecorated reflective surface elements together reproduce the background with dynamic characteristics.
- Different reflection characteristics refer to one or a combination of different reflection colors, different reflection brightness, or different reflection textures when the modified curved surface area and the unmodified curved surface area are irradiated by incident light.
- the animation frame can be observed at the corresponding observation angle of each animation frame, wherein the pattern of the observed animation frame is presented by the modified surface area, and it is observed that The background of the animation frame is rendered by the undecorated surface area.
- a group of animation frames visible in the preset observation angle set ⁇ v refers to a one-to-one correspondence between observation angles and animation frames, and one observation angle corresponds to one animation frame.
- the dynamic features in the embodiments of the present application essentially refer to dynamic features that appear when the observation angle is changed.
- the viewing angle can be the angle of one or more of the three elements, the light source (ie the incident light), the element and the observer.
- the observation direction is defined by the connecting line between the observer's eyes and the observed point, thereby defining the observation angle.
- the observation angle is a three-dimensional space parameter, so it needs to be decomposed into at least two angles for accurate description.
- the pitch angle and the azimuth angle can be used to describe together, or the angle between the observation direction and the three coordinate axes of x, y, and z can be used to describe together.
- the pattern of the animation frame can be designed as letters, numbers, characters, symbols or geometric shapes (especially circles, ovals, triangles, rectangles, hexagons or stars, etc.).
- the above-mentioned dynamic features generally refer to any translation, rotation, scaling, deformation, looming, yin-yang conversion, etc. of the design pattern directly visible to the human eye presented by the element, and can also be any combination of these dynamic features.
- the translation can be designed to design the pattern to translate in a specific direction, or it can be designed to translate in multiple directions, and the translation direction is associated with the observation direction.
- a common combination feature is that when the position of the design animation frame pattern changes, its shape also changes, for example, a circle turns into a square.
- the dynamic feature can have the orthogonal parallax motion behavior of the pattern, that is, the motion direction of the pattern is always perpendicular to the change of the observation direction, which further attracts the observer's attention through the counter-intuitive phenomenon.
- the motion of the animation frame pattern can create a three-dimensional effect that floats above or below the plane of the element through the principle of binocular horizontal parallax.
- the pattern may also include multiple sub-patterns exhibiting the same or different motion behaviors and/or the same or different fly heights or depths.
- the pattern may comprise at least a first curve and a second curve which appear as a first or a second curve located at the center of the first or second area respectively when viewed from the first or second viewing direction, respectively. target curve.
- the two curves preferably move in different (preferably opposite) directions, resulting in a particularly dynamic appearance.
- the pattern of the security element may also comprise more than two curves which may move in the same or different directions when the security element is tilted.
- a curve in the form of an alphanumeric string may alternately exhibit different motion behaviors, such as alternately floating above or below the plane of the flat pattern area, and moving according to its floating height when tilted.
- the terms "pattern” and "pattern area” can be replaced with each other.
- Dynamic features can be represented by a set of pictures generated by computer software, such as mathematical calculation software, pattern processing software, etc., during specific design. For example, using a bitmap in the format of bmp, the design patterns of different colors and the common background of the patterns are reflected through the gray value of 0-255. Each picture corresponds to the visual information presented to the human eye under a specific viewing angle, which is called a frame animation of the designed dynamic feature.
- the preset observation angle set ⁇ v refers to all the preset dynamic features that can be seen when the observation angle of the human eye changes within the set. Optical anti-counterfeiting elements may reflect illuminating light out of the set, but these reflected light may be unrelated to the designed animated feature, or may provide a darker or darker visual information for the dynamic feature.
- the preset observation angle set ⁇ v can be described by the azimuth angle and the elevation angle.
- the azimuth angle can be designed to be 0-360°
- the elevation angle can be 0-35° or 10-50°, etc., that is, when the human eye is in this Dynamic features can be seen in the conical area.
- the setting of the angle parameter depends on the purpose of the designer, the lighting environment possessed by the observer, the viewing habits, and so on.
- the diffusely reflective surface S area can use the pitch and azimuth angles to determine the orientation of the various curved areas.
- other parameters can also be used to determine the orientation of the surface area, especially parameters that are orthogonal to each other, such as two orthogonal components of the direction of the surface area.
- the wave characteristic length of the diffusely reflective surface S that is, the average distance between adjacent wave crests and wave troughs, is preferably smaller than the recognition ability of the human eye. Discrimination power is typically around 100 ⁇ m, with closer distances increasing the resolving power. Therefore, the average distance between adjacent peaks and valleys should not be greater than 100 ⁇ m.
- the lateral dimension is at a distance of 5 ⁇ m to 100 ⁇ m, sufficiently fine features can be produced without producing obvious diffractive iridescence, and the lateral dimension can be further preferably 10 ⁇ m to 30 ⁇ m.
- the average distance between the crests and the troughs in the diffusely reflective surface S can be calculated by the following method. Select a square area with area A in the diffuse reflection surface S, find the number N of wave crests contained in the area A, and consider that the number of wave crests and wave troughs is basically the same, then the above average distance
- the diffusely reflective curved surface S is continuous and smooth, that is, the curved surface has no breakpoints and cracks, and the curved surface has no edges and corners. Satisfy the first derivative are basically continuous.
- the accuracy of actual fabrication is limited, and the purpose of the present application can be achieved with the diffusely reflective curved surface S being roughly smooth.
- the diffusely reflective curved surface S is smooth everywhere in practical use, and most areas, such as curved surfaces with an area of more than 80%, have smooth properties, which can achieve the purpose of the present application.
- the diffusely reflective surface S may be periodic in at least one direction, for example, the diffusely reflective surface S may be periodic in both x and y directions, such as a surface determined by the following expression:
- p x represents the period in the x direction
- p y represents the period in the y direction
- x and y represent the independent variables
- coefficients C n , N can be set, and a periodic function can be constructed using the following formula, where N is a positive integer.
- a computer program can be used to generate a random height matrix of the matrix, and the value of the height matrix represents several scattered points on the diffuse reflection surface S.
- the non-periodic diffuse reflection surface SS can be obtained by a certain difference processing or blurring processing of this matrix.
- the main function of the diffusely reflective curved surface S is to generate uniform reflected light at the set preset viewing angle set ⁇ v, which is similar to the visual impression of diffuse reflection produced by general office paper.
- the orientation of each curved surface area needs to be selected from the continuous set of angles ⁇ s, and the orientation can be defined by, for example, an azimuth angle and an elevation angle.
- the selection of the angle continuum set ⁇ s must uniformly reflect the incident light to at least the preset observation angle set ⁇ v, so ⁇ s must cover a minimum set jointly determined by the incident light directions ⁇ i and ⁇ v.
- the reflective surface S reflects the incident light to the angle set ⁇ r, which covers the preset observation angle set ⁇ v, that is, ⁇ v is a subset or proper subset of ⁇ r.
- ⁇ s is designed to be the smallest set jointly determined by the incident light directions ⁇ i and ⁇ v, that is, ⁇ v is the same as ⁇ r.
- the azimuth angle of the element of ⁇ s is the same as the azimuth angle of the element of ⁇ v
- the pitch angle of its element is half the pitch angle of the element of ⁇ v.
- the diffuse reflective surface In order to realize the dynamic feature, it is necessary to modify the diffuse reflective surface according to each pixel point of each animation frame, so as to change the uniform reflected light distribution in the observation angle set ⁇ v.
- the size of the diffuse surface should be larger than the size of the area occupied by all animation frames, so that each animation frame can correspond to the diffuse surface without scaling, so that each pixel in the pattern area of the animation frame is The corresponding position point can be found on the diffuse surface, and the position point will be modified.
- the position Pv of the pattern area contained in an animation frame and the observed angle ⁇ v find the position Ps and angle ⁇ s of the surface area to be modified. For example, you can find the position and angle of the surface area to be modified per pixel. angle.
- Pv and Ps should be at the same position, and the reflection law of geometric optics should be satisfied between ⁇ v, ⁇ s and the incident light angle ⁇ i, that is, the normals of the incident light, reflected light, and surface area are in the same plane, and the incident light is in the same plane.
- the angle is equal to the reflection angle.
- the selection of the position deviation ⁇ P and the angle deviation ⁇ is determined according to the size of the surface area, the resolution of the angle and size of the human eye, and the designed dynamic characteristics.
- the principle is that at least one surface area that should be modified can be found.
- the patterns do not produce differences discernible to the human eye.
- the position deviation ⁇ P is less than 100 ⁇ m, preferably less than 50 ⁇ m
- the angle deviation ⁇ is defined as the angle between the normal direction of the modified surface area and the normal direction of the surface area corresponding to the preset observation angle of the pattern, and the angle deviation ⁇ should be less than 3 °, preferably less than 0.5°.
- each animation frame can be pixelated, and the diffuse surface can be pixelated.
- the pattern area of each animation frame can be pixelated.
- the essence of pixelation is to divide the animation frame into, for example, N ⁇ M small areas, and the area occupied by each small area can be very small, for example.
- Similar diffuse surfaces can be pixelated into small regions that can be very small.
- the width of each small area in the embodiments of the present application may be 0.5 ⁇ m to 10 ⁇ m, preferably 2 ⁇ m to 4 ⁇ m, and correspondingly, the length of each small area may be 0.5 ⁇ m to 10 ⁇ m, preferably 2 ⁇ m to 4 ⁇ m.
- the first azimuth angle and the first pitch angle of each animation frame can be determined, and each animation frame corresponds to a specific observation angle, so the first azimuth angle and the first pitch angle can be determined according to the observation angle of the animation frame.
- the observation angle is a direction vector in a rectangular coordinate system.
- the angle between the direction vector and the xy plane is defined as the pitch angle (which can also be said to be the complementary angle to the z-axis).
- the direction vector is projected onto the xy plane to form a projection vector, and the angle between the projection vector and the x-axis is defined as the azimuth angle.
- the second azimuth angle and the second elevation angle of each pixel of the diffusely reflective surface may be determined, and the second azimuth and the second elevation angle are determined according to the normal vector at the pixel of the diffusely reflective surface.
- the azimuth angle of a pixel can be defined as the angle between the normal vector at the pixel and the x-axis
- the pitch angle can locate the angle between the normal vector at the pixel and the z-axis.
- the xy plane is the plane where the optical anti-counterfeiting element is located
- the x-axis can be the longitudinal direction of the optical anti-counterfeiting element
- the y-axis can be the lateral direction of the optical anti-counterfeiting element
- the z-axis can be the same as the optical anti-counterfeiting element. vertical axis.
- the following steps may be performed: finding a first azimuth and a first pitch of the animation frame at a location of the diffuse surface corresponding to the pixels of the pattern area in the animation frame Pixels corresponding to the second azimuth angle and the second pitch angle whose angles are matched, thereby forming an area corresponding to the pattern area of the animation frame in the diffusely reflective surface.
- a set of animation frames can be vertically projected on the diffuse reflection surface in the same proportion, so that the position on the diffuse reflection surface corresponding to each pixel in each animation frame can be determined.
- Finding the pixels corresponding to the second azimuth and the second pitch angle that match the first azimuth and the first pitch angle of the animation frame may include: a preset of pixels in the pattern area of the diffusely reflective surface that match the animation frame Within the distance range, find the second azimuth angle whose angle difference from the first azimuth angle is within the range of the first preset angle difference, and the angle difference between the first pitch angle and half of the first pitch angle is within the second preset angle difference range.
- the pixel corresponding to the second pitch angle within the range of the angle difference.
- the difference in azimuth angle becomes unimportant.
- the azimuth angle may not be considered, and only within the preset distance range, the angular difference between the first pitch angle and one-half of the first pitch angle can be found to be within the second preset angle difference range.
- the pixel corresponding to the second pitch angle.
- the preset distance range means that the distance from the position of the pixel in the pattern area in the animation frame is less than 100 ⁇ m, preferably less than 50 ⁇ m.
- the first preset angle difference range means that the angle difference from the first azimuth angle is less than 3°, preferably less than 0.5°.
- the second preset angle difference range means that the angle difference from the half of the first pitch angle is less than 3°, preferably less than 0.5°.
- one or more eligible pixels may be found in the diffuse surface, and the one or more eligible pixels can be modified. After finding pixels in the diffuse surface that match each pixel of the pattern area of the animation frame, these matched pixels form the area corresponding to the pattern area of the animation frame.
- the modified surface area can be formed by modifying the area corresponding to the pattern area of each animation frame formed in the diffuse reflective surface.
- the modification of the curved surface area can add secondary structures to the modified curved surface area.
- the feature size of the secondary structure is significantly smaller than that of the curved surface area, so it can be spread on the surface of the curved surface area along the direction of the curved surface area.
- the characteristic size of the surface area of a diffusely reflective surface can be characterized by the average distance between adjacent peaks and troughs.
- the lateral feature size of the secondary structure is 0.2 ⁇ m to 5 ⁇ m, which can produce diffraction or absorption of visible light.
- the absorption can be based on the principle of surface plasmon resonance absorption, and the sub-wavelength scale grating structure absorbs the incident light of a specific frequency set, thereby changing the color of the reflected light while maintaining the original reflection direction.
- the subwavelength structure becomes optical absorption or optical absorption. black structure.
- the surface area to be modified can have a secondary structure as a whole before modification, which can generate a uniform reflected light distribution within the set of observation angles ⁇ v, and provide specific color or brightness characteristics at the same time. Therefore, the modification of the surface area can smooth the part or the whole of the modified surface area. For example, the secondary structure of the modified curved surface area is removed, so that it can produce specular reflection with higher reflectivity in the full wavelength range of visible light.
- at least a portion of the unmodified surface area may be provided to be smooth or with secondary structures.
- the modification of the surface area may be to flatten the modified surface area, so that the modified surface area can only reflect incident light to a specific direction. At other viewing angles, the modified area provides little or no reflected light, resulting in a darker or darker visual perception than other areas.
- the modification to the curved surface area may be to adjust the angle of the modified curved surface area, so that the modified curved surface area reflects all the light rays incident on the modified curved surface area to a direction exceeding the preset observation angle set ⁇ v.
- the pitch angle of the curved surface area is increased and exceeds a minimum set jointly determined by the incident light directions ⁇ i and ⁇ v, and the incident light can be reflected to exceed the set determined by ⁇ v.
- the modified curved area provides little or no reflected light, resulting in a darker or darker visual perception than other areas.
- the surface on which the modified curved region is located or the surface opposite the surface on which the modified curved region is located may have a coating or coating.
- the reflection-enhancing coating, coating or reflective ink layer preferably has a color-shifting effect, ie a hue change of the color at different viewing angles, for example using a Fabry-Perot interference structure.
- the reflective and curved regions can also be imprinted in the reflective ink layer or the ink absorbing layer.
- the modification to the curved surface area can be that the modified curved surface area is formed into a convex or concave compared with the surrounding unmodified curved surface area; or the modification to the curved surface area can be that the coating or coating thickness of the modified curved surface area is different from that of the unmodified curved surface area.
- Retouched surface area there is a reflective coating, coating, or ink in the modified curved area, and no reflective coating, coating, or ink in the unmodified curved area; or no reflective plating, coating, or ink in the modified curved area or ink, while having a reflective coating, coating or ink on unmodified curved areas.
- the modification to the surface area can be a serial combination of the above-mentioned modification methods. For example, a lower recess is formed in the modified surface area than the unmodified surface area, then secondary structures are added in the recess, and finally the reflective coating in the secondary structure area is removed (ie, the same as the unmodified surface area).
- the reflective coating has different thickness); or, a lower depression is formed in the modified surface area than the unmodified surface area, and the color ink is filled in the depression, and its thickness is significantly larger than that of the ink in the unmodified surface area. thickness.
- Retouching of surface areas can be combined in parallel with multiple retouching methods.
- a flat depression is formed in a part of the modified curved surface area, and secondary structures are added along the direction of the curved surface area in another part of the modified curved surface area.
- the modification to the surface area can be used in combination of the above modification methods of serial combination and parallel combination.
- the width of the modified region is 0.5 ⁇ m to 20 ⁇ m, preferably 2 ⁇ m to 10 ⁇ m.
- the modified surface area has one or a combination of different reflection colors, different reflection brightness, and different reflection textures than the unmodified surface area.
- the modified curved surface areas together appear as a pattern of animation frames, and the unmodified surface areas together appear as the background of the animation frames.
- the pattern area has a different optical contrast than the background area, which can be one or a combination of different colors, different brightness, and different textures visible to the human eye.
- an embodiment of the present application also provides a design method for an optical anti-counterfeiting element.
- the design method may include: designing a dynamic feature, where the dynamic feature is a set of animation frames visible at a preset viewing angle set ⁇ v, and the animation frames include: A pattern area and a background area that forms optical contrast with the pattern area; a roughly smooth diffusely reflective curved surface designed for optical anti-counterfeiting elements, so that incident light can be reflected by the diffusely reflective curved surface within a range not less than the set of preset viewing angles ⁇ v A roughly uniform brightness distribution is formed in the interior; based on the observation angle of each animation frame of a group of animation frames, the area corresponding to the pattern area of each animation frame is modified to form a modified surface area, so that the modified surface area is the same as the one. Unmodified surface areas have different reflection characteristics. When the diffusely reflective surface is illuminated by incident light, the modified surface areas together appear as a dynamic feature pattern, and the unmodified surface regions together appear as a
- Dynamic features can be represented by a set of pictures generated by computer software, such as mathematical calculation software, pattern processing software, etc., during specific design. For example, using a bitmap in the format of bmp, the design patterns of different colors and the common background of the patterns are reflected through the gray value of 0-255. Each picture corresponds to the visual information presented to the human eye under a specific viewing angle, which is called a frame animation of the designed dynamic feature.
- computer software such as mathematical calculation software, pattern processing software, etc.
- the embodiment of the present application further provides an anti-counterfeiting product using the optical anti-counterfeiting element of any embodiment of the present application.
- the anti-counterfeiting product can be in the form of anti-counterfeiting thread, anti-counterfeiting strip, and anti-counterfeiting label.
- the embodiments of the present application further provide a data carrier having the anti-counterfeiting element according to any embodiment of the present application or the anti-counterfeiting product according to any embodiment of the present application, and the anti-counterfeiting element or the anti-counterfeiting product can be arranged in the opaque area of the data carrier and in the data carrier. in or above the transparent window area or through opening.
- the data carrier can in particular be a document of value, such as bank notes (especially paper bank notes, polymer bank notes or film composite bank notes), stocks, warrants, certificates, tickets, checks, high-value tickets, but also Is an identification card, such as a credit card, bank card, cash card, authorization card, personal identification card, or the personal information page of a passport, etc.
- optical anti-counterfeiting element provided in real time by the present application and the manufacturing method thereof will be further described below with reference to the accompanying drawings.
- FIG. 1 is a schematic diagram of the diffuse reflection effect of the diffusely reflective curved surface area of the optical anti-counterfeiting element on incident light.
- the plane where the optical anti-counterfeiting element 1 is located is defined as the xy plane, and the diffusely reflective curved surface S is composed of a plurality of smoothly connected curved surface areas 3 .
- a smooth connection means that the first derivative of the two surfaces to be connected is continuous, that is to say, there is no connection but is connected, and there is no break and no corrugation.
- the curved area 3 can have protrusions and depressions.
- the optical anti-counterfeiting element 1 has a base material 6, and the diffusely reflective curved surface S is located on one side of the base material.
- the presence of the substrate 6 is a requirement of the manufacturing process, which may not be part of the optical security element 1 itself.
- the substrate 6 can be used as a part of the anti-counterfeiting product formed by the optical anti-counterfeiting element 1 .
- the base material 6 can also be removed in the anti-counterfeiting product, for example, in a hot stamping product, the structural layer is transferred to another carrier, and the base material 6 does not become a part of the anti-counterfeiting product.
- the substrate 6 does not become an essential component of the optical anti-counterfeiting element 1 .
- the incident light 4 is incident on the side of the substrate 6 with the diffusely reflective curved surface S, and the incident light 4 is reflected by the diffusely reflective curved surface S to form a plurality of reflected rays 5 in different directions.
- angles the angles are defined by, for example, azimuth angle and pitch angle
- a substantially uniform diffuse reflection visual effect covers a predetermined set of viewing angles ⁇ v of predetermined dynamic features.
- the direction of the incident light 4 is set as the z direction, which is the direction perpendicular to the xy plane.
- the azimuth angle of the elements of the set ⁇ v is predetermined to be 0°-360°, and the elevation angle is predetermined to be 0°-35°. Accordingly, the average distance between the peaks and troughs of the diffusely reflective curved surface can be controlled in the range of 20 ⁇ m to 50 ⁇ m, and the longitudinal height can be set to 0 ⁇ m to 10 ⁇ m, so that the incident light 4 is reflected by the diffusely reflective curved surface S to the angle set ⁇ r, ⁇ r can cover the preset observation angle set ⁇ v.
- the coverage of this application specifically means that any element in the set ⁇ v can find a sufficiently close corresponding element in ⁇ r, such as the angle between the two. not more than 1°.
- the reflective smooth surface should contain at least 3000 peaks and troughs, preferably more than 50000, so as to produce a sufficiently fine and uniform reflected light distribution.
- FIG. 1 only shows that the diffusely reflective curved surface of the optical anti-counterfeiting element can produce a diffuse reflection effect on incident light, and does not involve specific dynamic characteristics and modification methods for the curved surface area.
- FIG. 2 illustrates a design method of a periodic diffusely reflective curved surface.
- This formula produces a smooth diffuse surface with periodicity in both the x and y directions.
- the pitch angle of each area of the diffusely reflective curved surface can be adjusted as a whole by adjusting the overall undulating height of the diffusely reflective curved surface S as required.
- Both sine and cosine functions are infinitely derivable, so the equation S(x, y) fully satisfies the requirements of continuity and smoothness.
- Fx represents the first derivative of the function F(x,y,z) with respect to x
- Fy represents the first derivative of the function F(x,y,z) with respect to y
- Fz represents the first derivative of the function F(x,y,z) on The first derivative of z.
- the azimuth angle ⁇ (defined as the angle between the normal vector and the x -axis) and the pitch angle ⁇ (defined as the angle between the normal vector and the z-axis ) can be directly obtained from the normal vector.
- horn The azimuth angle ⁇ (defined as the angle between the normal vector and the x -axis) and the pitch angle ⁇ (defined as the angle between the normal vector and the z-axis ) can be directly obtained from the normal vector.
- Figure 3 exemplifies an aperiodic diffuse reflective surface design method.
- the non-periodic diffuse reflection surface S one method is to use a computer program to generate a matrix random height matrix, and the value of this height matrix represents several scattered points on the diffuse reflection surface S.
- the aperiodic diffuse reflection surface S can be obtained by a certain difference processing or blurring processing of this matrix. Difference processing can use bilinear interpolation, resampling using pixel area relationship, bicubic interpolation of 4 ⁇ 4 pixel neighborhood, or Lanczos interpolation of 8 ⁇ 8 pixel neighborhood, etc., while blur processing can use average blur, Defocus blur, motion blur, or Gaussian blur.
- Difference processing or blurring processing can ensure that there is no steep change and break between heights, thus ensuring the smooth characteristics of the diffuse reflection surface, that is, the first derivative is basically continuous.
- Random heights can be generated using pseudo-random numbers, which are strings of numbers that appear random but are calculated by deterministic algorithms, so they are not truly random numbers in the strict sense.
- pseudorandom numbers are widely used because the statistical properties of pseudorandom selection (such as equal probability of individual numbers or statistical independence of consecutive numbers) are usually sufficient for practical purposes, and unlike true random numbers, pseudorandom numbers are Random numbers are easily generated by computers.
- the specific surface area of the diffuse reflection area is modified to generate locally different reflection characteristics.
- the incident light angle ⁇ i is set to be along the z-axis direction.
- Figures 4 and 5 provide two examples to illustrate how to determine the surface area to be modified.
- FIG. 4 is an embodiment of determining the surface area to be retouched according to the animation frame.
- the two tables in FIG. 4 represent the pitch and azimuth angles of the local curved area, respectively. Due to the limited sampling density of discrete data, the data of the pitch angle and azimuth angle in Fig. 4 do not clearly reflect the smooth characteristics of the diffuse reflection surface S, which does not affect the principle description of how to use the animation frame to determine the surface area to be modified in this embodiment.
- 71 is the pattern area of the animation frame
- 72 is the background area of the animation frame. 71 and 72 have optical contrast visible to the human eye.
- the size of the reflection area 21 corresponding to the animation frame 7 on the diffuse reflective surface S is at least not smaller than the size of the area where the animation frame 7 is located, so that the visual information of the animation frame 7 can be completely presented. Taking any point Pv on the pattern area 71 (which can also be considered as any pixel point) as an example, the corresponding point of Pv is determined in the reflection area 21 .
- the corresponding point of any point Pv in the reflection area 21 can always be found, that is, the curved surface area to be modified can be found.
- the modification of the surface area corresponding to this point can produce the expected visual contrast at the Pv point of animation frame 7.
- FIG. 5 is another embodiment of determining the surface area to be retouched according to the animation frame.
- the two tables in FIG. 5 represent the pitch angle and azimuth angle of the local curved area, respectively. Due to the limited sampling density of discrete data, the pitch angle and azimuth angle data in FIG. 5 do not clearly reflect the smoothness of the curved surface S, which does not affect the principle description of how to use animation frames to determine the curved surface area to be modified in this embodiment.
- 81 is the pattern area of the animation frame 8
- 82 is the background area of the animation frame 8
- the pattern area 81 and the background area 82 have an optical contrast visible to the human eye.
- the size of the reflection area 22 corresponding to the animation frame 8 on the diffuse reflective surface S is at least not smaller than the size of the area where the animation frame 8 is located, so that the visual information of the animation frame 8 can be completely presented.
- the corresponding point of Pw is determined in the reflection area 22 .
- the curved surface area to be modified can always be found in the reflection area 22 .
- 91 indicates that the modification of the curved surface area is to form a depression in the modified curved surface area relative to the periphery (for example, the unmodified curved surface area). related.
- the modification of the curved surface area can be to make the modified curved surface area flat, so that the modified curved surface area can only reflect the incident light to a specific reverse direction. Under other viewing angles, the modified curved surface area None or very little reflected light is provided, resulting in a darker or darker visual perception than other areas.
- 92 indicates that the modification of the curved area can add a secondary structure to the modified area.
- the characteristic scale of the secondary structure is significantly smaller than the size of the curved area, so it can be spread on the surface of the curved area along the direction of the curved area.
- the lateral feature size of the secondary structure is 0.2 ⁇ m to 5 ⁇ m, which can produce diffraction or absorption of visible light.
- the absorption can be based on the principle of surface plasmon resonance absorption, and the sub-wavelength scale grating structure absorbs the incident light of a specific frequency set, thereby changing the color of the reflected light while maintaining the original reflection direction.
- the subwavelength structure becomes optical absorption or optical absorption. black structure.
- the modified curved surface area may have a secondary structure as a whole before modification, which produces a uniform reflected light distribution in the observation angle set ⁇ v, and provides specific color or brightness characteristics. Therefore, the modification of the curved surface area can make the modified curved surface area smooth, that is, remove the secondary structure of the curved surface area to be modified, so that it can produce specular reflection with higher reflectivity for the entire visible light band.
- the surface on which the modified curved area is located or the surface opposite to the surface on which the modified curved area is located may have a coating or coating Floor.
- the reflection-enhancing coating, coating or reflective ink layer preferably has a color-shifting effect, i.e. a hue change of the color at different viewing angles, e.g. with a Fabry-Perot interference structure, e.g. Cr(5nm)/MgF2 ( 500nm)/ Al (50nm) structure.
- the reflective and curved regions can also be imprinted in the reflective ink layer or the ink absorbing layer.
- the modification to the curved area may be that the coating or coating thickness of the modified curved area is different from that of the unmodified curved area.
- there is a reflective coating, coating, or ink in the modified curved area and no reflective coating, coating, or ink in the unmodified curved area; or no reflective plating, coating, or ink in the modified curved area or ink, while having a reflective coating, coating or ink on unmodified curved areas.
- the modification to the curved surface area may be to adjust the angle of the modified curved surface area, so as to reflect the incident light to a direction exceeding the preset observation angle set ⁇ v.
- the pitch angle of the curved surface area is increased and exceeds a minimum set jointly determined by the incident light directions ⁇ i and ⁇ v, and the incident light can be reflected to exceed the set determined by ⁇ v.
- the modified curved area provides little or no reflected light, resulting in a darker or darker visual perception than other areas.
- 96 indicates that the modification to the surface area can be used in a serial manner of multiple modification methods. For example, forming a lower depression in the modified surface area than the surrounding area, then adding a secondary structure in the depression, and finally removing the reflective coating in the secondary structure area (ie, having a different thickness from the unmodified surface area) ; Or form a depression lower than the surrounding area in the modified curved surface area, and fill the color ink in the depression, the thickness of which is significantly larger than the thickness of the ink in the unmodified curved surface area.
- 97 indicates that the modification to the curved surface area can be used in parallel with multiple modification methods.
- a flat depression is formed in a part of the modified curved surface area, and secondary structures are added along the direction of the curved surface area in another part of the modified curved surface area.
- the modification to the surface area can be used in combination of the above modification methods of serial combination and parallel combination.
- the modified part can exist in part or the whole of the modified surface area.
- the trimmed portion will be equal to the trimmed surface area.
- the modified part will exist locally in the modified surface area.
- the width of the modified region is 0.5 ⁇ m to 10 ⁇ m, preferably 2 ⁇ m to 4 ⁇ m.
- the modified surface area has one or a combination of different reflection colors, different reflection brightness, and different reflection textures than the unmodified surface area.
- Part of the curved areas 31 and 32 of the diffusely reflective curved surface S in FIG. 6 reflect the incident light 4 to directions 51 and 52, respectively.
- the reflected light of the modified curved surface area 31 generates the pattern of the animation frame, that is, the modified curved surface area presents the pattern of the animation frame together;
- the reflected light of the unmodified curved surface area 32 generates the background of the animation frame, that is, the unmodified curved surface area 32 generates the background of the animation frame.
- the retouched surface areas are collectively rendered as the background of the animation frame.
- the pattern area has a different optical contrast than the background area, which can be one or a combination of different colors, different brightness, and different textures visible to the human eye.
- FIG. 7 shows a schematic view of a banknote 10 having the optical security element of the present application, which is embedded within the banknote 10 in the form of a window security thread 101 .
- the optical anti-counterfeiting element can also be used in the form of labeling 102 , and an opening area 103 can be formed on the banknote 10 to facilitate light-transmitting observation.
- the present application is not limited to anti-counterfeiting threads and banknotes, but can be used in various anti-counterfeiting products, such as in labels on goods and packaging, or in anti-counterfeiting documents, ID cards, passports, credit cards, health cards, etc. middle.
- wider security strips or transfer elements can be used, for example.
- An embodiment of the present application provides a storage medium on which a program is stored, and when the program is executed by a processor, the design method for an optical anti-counterfeiting element according to any embodiment of the present application is implemented.
- An embodiment of the present application provides a processor, where the processor is used to run a program, wherein the design method for an optical anti-counterfeiting element according to any embodiment of the present application is executed when the program runs.
- An embodiment of the present application provides an electronic device, the device includes a processor, a memory, and a program stored in the memory and executable on the processor, and the processor implements the optical anti-counterfeiting element according to any embodiment of the present application when the processor executes the program. design method.
- the present application also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program initialized with the steps of the design method for an optical anti-counterfeiting element of any embodiment of the present application.
- the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
- computer-usable storage media including, but not limited to, disk storage, CD-ROM, optical storage, etc.
- These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions
- the apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.
- a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.
- processors CPUs
- input/output interfaces network interfaces
- memory volatile and non-volatile memory
- Memory may include non-persistent memory in computer readable media, random access memory (RAM) and/or non-volatile memory in the form of, for example, read only memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium.
- RAM random access memory
- ROM read only memory
- flash RAM flash memory
- Computer-readable media includes both persistent and non-permanent, removable and non-removable media, and storage of information may be implemented by any method or technology.
- Information may be computer readable instructions, data structures, modules of programs, or other data.
- Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), Flash Memory or other memory technology, Compact Disc Read Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, Magnetic tape cartridges, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information that can be accessed by a computing device.
- computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.
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Abstract
本申请提供一种光学防伪元件及其设计方法、防伪产品。光学防伪元件具有大致平顺的漫反射性曲面,入射光被漫反射性曲面反射后可在不小于预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;漫反射性曲面包括被修饰的曲面区域和未被修饰的曲面区域,被修饰的曲面区域和未被修饰的曲面区域具有不同的反射特性,其中,被修饰的曲面区域与动画帧的图案区域相对应;在漫反射性曲面被入射光照射时,被修饰的曲面区域共同呈现为动感特征的图案,未被修饰的曲面区域共同呈现为动感特征的背景。其制造工艺简单且可灵活实现颜色和/或明暗对比等的动感特征。
Description
相关申请的交叉引用
本申请要求于2021年4月25日提交至中国专利局、申请号为202110449712.1,申请名称为“光学防伪元件及其设计方法、防伪产品”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
本申请涉及防伪技术领域,具体地涉及一种光学防伪元件及其设计方法、防伪产品。
为了防止利用扫描和复印等手段产生的伪造,钞票、金融票据等各类高安全或高附加值产品中广泛采用了光学防伪技术,并且取得了非常好的效果。
目前,引人注目的技术是由制版决定的微结构与光变层相结合,如中国专利CN 102712207 A和CN 107995894 A公开的,通过预先设计的微反射面调制反射光线的亮度分布,从而实现动感效果,并可以叠加干涉镀层实现颜色变化和动感效果的结合。这通常可产生图案,如线条、圆环、曲线或文字的多种运动效果,并可以产生三维立体感。但是,绝大多数情况下,图案和背景的颜色色调只能是相同的,明暗对比关系也基本是单一的,难以实现多种颜色或任意明暗关系的动感特征。
通过基于微透镜和微图案的莫尔放大构造还能产生具有三维深度效果的展示图,例如专利WO 2005/052650 A2中所述。在此,利用由具有相似但不完全相同周期的微透镜组成的网格放大由很多小微图案构成的周期性展示图。通过这种方式,能够产生明显位于实际表面之前或之后的立体感,或者能够产生所谓的正交视差运动。但是,这种莫尔放大构造的不利之处在于其制造比较复杂,需要用于微透镜和微图案的两个压印步骤,且两步之间需要精确的对准。
最后,例如专利WO2014/108303A1中所述,将磁性排列的反射颜料与具有相应形状的磁体对准,从而产生可包括一定的深度效果的明亮(尤其是环状)的动感效果。这种效果非常明亮且很容易看清,但是所需的磁性油墨较昂贵,并且效果的种类和分辨率受可用磁体的限制,难以随意调节。
以上申请除了已列出的不足外,都采用了“单元”形式的结构,例如微反射面、颜 料片、微透镜单元,单元之间斜率的突变和空隙不可避免的造成无法充分表示元件的展示面积,并降低图像的分辨率。因此,需要开发一种表现力足够细致、制造工艺简单且可灵活实现颜色和/或明暗对比等的动感特征的光学防伪元件。
申请内容
本申请实施例的目的是提供一种光学防伪元件及其设计方法、防伪产品,其制造工艺简单且可灵活实现颜色和/或明暗对比等的动感特征。
为了实现上述目的,本申请实施例提供一种光学防伪元件,光学防伪元件能够呈现动感特征,动感特征被预先设计为一组在预设观察角度集合Ωv可见的动画帧的再现,动画帧包括图案区域和与图案区域形成光学对比度的背景区域;光学防伪元件具有大致平顺的漫反射性曲面,入射光被漫反射性曲面反射后可在不小于预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;漫反射性曲面包括被修饰的曲面区域和未被修饰的曲面区域,被修饰的曲面区域和未被修饰的曲面区域具有不同的反射特性,其中,被修饰的曲面区域与图案区域相对应;在漫反射性曲面被入射光照射时,被修饰的曲面区域共同呈现为动感特征的图案,未被修饰的曲面区域共同呈现为动感特征的背景。
可选的,漫反射性曲面至少在一个方向上是周期性的。
可选的,漫反射性曲面至少在一个方向上是非周期性的。
可选的,漫反射性曲面的相邻波峰和波谷之间的平均距离为5μm至100μm,优选为10μm至30μm。
可选的,漫反射性曲面的相邻波峰和波谷之间的平均高度差为1μm至10μm。
可选的,未被修饰的曲面区域的至少一部分为光滑的或是带有次级结构的。
可选的,被修饰的曲面区域通过以下多种方式中的一者或多者被修饰:使被修饰的曲面区域增加次级结构;使被修饰的曲面区域变得光滑;使被修饰的曲面区域变得平坦;使被修饰的曲面区域设置为与未被修饰的曲面区域相比具有凸起或凹陷;调整被修饰的曲面区域的角度,使得入射光被反射至超出预设观察角度集合Ωv的范围;或者使被修饰的曲面区域的镀层或涂层的厚度调整为不同于未被修饰的曲面区域。
可选的,在被修饰的曲面区域通过多种方式中的两种或两种以上的方式被修饰的情况下,两种或两种以上的方式以并行组合和/或串行组合的方式存在。
可选的,次级结构的横向特征尺寸为0.2μm至5μm。
可选的,被修饰的曲面区域的宽度为0.5μm至20μm,优选为2μm至10μm。
可选的,不同的反射特性是指被修饰的曲面区域与未被修饰的曲面区域在入射光照射时具有不同反射颜色、不同反射亮度、或者不同反射质感的一种或其组合。
相应的,本申请实施例还提供一种用于光学防伪元件的设计方法,设计方法包括:设计一动感特征,动感特征为一组在预设观察角度集合Ωv可见的动画帧的再现,动画帧包括图案区域和与图案区域形成光学对比度的背景区域;设计用于光学防伪元件的大致平顺的漫反射性曲面,使得入射光被漫反射性曲面反射后可在不小于预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;基于一组动画帧的各动画帧的观察角度,对与各动画帧的图案区域相对应的区域进行修饰以形成被修饰的曲面区域,使得被修饰的曲面区域与未被修饰的曲面区域具有不同的反射特性,在漫反射性曲面被入射光照射时,被修饰的曲面区域共同呈现为动感特征的图案,未被修饰的曲面区域共同呈现为动感特征的背景。
可选的,漫反射性曲面至少在一个方向上是周期性的。
可选的,漫反射性曲面至少在一个方向上是非周期性的。
可选的,漫反射性曲面的相邻波峰和波谷之间的平均距离为5μm至100μm,优选为10μm至30μm。
可选的,漫反射性曲面的相邻波峰和波谷之间的平均高度差为1μm至10μm。
可选的,基于一组动画帧的各动画帧的观察角度,对与各动画帧的图案区域相对应的区域进行修饰以形成被修饰的曲面区域,包括:将一组动画帧中的每一个动画帧和漫反射性曲面进行像素化;确定每一个动画帧的第一方位角和第一俯仰角,第一方位角和第一俯仰角根据动画帧的观察角度被确定;确定漫反射性曲面的各像素的第二方位角和第二俯仰角,第二方位角和第二俯仰角根据漫反射性曲面的像素处的法向量确定;针对一组动画帧中的每一个动画帧执行以下步骤:在漫反射性曲面的与动画帧中的图案区域的像素相对应的位置处,寻找与动画帧的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素,从而在漫反射性曲面中形成与动画帧的图案区域相对应的区域;以及对在漫反射性曲面中形成的与动画帧的图案区域相对应的区域进行修饰。
可选的,在漫反射性曲面与动画帧中的图案区域的像素相对应的位置处,寻找与图案区域的像素的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素,包括:在漫反射性曲面与动画帧中的图案区域的像素的预设距离范围内,寻找与二分之 一的第一方位角之间的角度差在第一预设角度差范围内的第二方位角、与第一俯仰角之间的角度差在第二预设角度差范围内的第二俯仰角对应的像素。
可选的,预设距离范围是指与动画帧中的图案区域的像素所在位置之间的距离小于100μm,优选小于50μm;和/或第一预设角度差范围是指与第一方位角之间的角度差小于3°,优选为小于0.5°;和/或第二预设角度差范围是指与第一俯仰角之间的角度差小于3°,优选为小于0.5°。
可选的,对与各动画帧的图案区域相对应的区域进行修饰以形成被修饰的曲面区域,包括执行以下方式中的一者或多者:使被修饰的曲面区域增加次级结构;使被修饰的曲面区域变得光滑;使被修饰的曲面区域变得平坦;使被修饰的曲面区域设置为与未被修饰的曲面区域相比具有凸起或凹陷;调整被修饰的曲面区域的角度,使得入射光被反射至超出预设观察角度集合Ωv的范围;或者使被修饰的曲面区域的镀层或涂层的厚度调整为不同于未被修饰的曲面区域。
可选的,动感特征为平动、转动、缩放、变形、隐现、阴阳转换的一种或其组合;和/或光学对比度为人眼可见的不同颜色、不同亮度、不同质感的一种或其组合。
可选的,被修饰的曲面区域的宽度为0.5μm至20μm,优选为2μm至10μm。
相应的,本申请实施例还提供一种使用上述的光学防伪元件的防伪产品。
相应的,本申请实施例还提供一种数据载体,数据载体具有上述的光学防伪元件,或者具有上述的防伪产品。
本申请实施例提供的光学防伪元件制造工艺简单且可灵活实现颜色和/或明暗对比等的动感特征,另外能够在宏观上呈现各种多色动感特征的同时,微观上不具有直接可识别的排布规则,从而在微结构设计和制造工艺等多维度增强伪造的难度。
本申请实施例的其它特征和优点将在随后的具体实施方式部分予以详细说明。
附图是用来提供对本申请实施例的进一步理解,并且构成说明书的一部分,与下面的具体实施方式一起用于解释本申请实施例,但并不构成对本申请实施例的限制。在附图中,为了清楚起见,图示不是按比例绘制的。在附图中:
图1为光学防伪元件的漫反射性曲面区域对入射光的漫反射作用示意图;
图2为一种周期性漫反射性曲面区域的设计示例图;
图3为一种非周期性漫反射性曲面区域的设计示例图;
图4为一个根据动画帧确定要被修饰的曲面区域的实施例;
图5为另一个根据动画帧确定要被修饰的曲面区域的实施例;
图6为被修饰的曲面区域的局部或整体的修饰方式示意图;
图7为光学防伪元件在钞票上使用的示意图。
以下结合附图对本申请实施例的具体实施方式进行详细说明。应当理解的是,此处所描述的具体实施方式仅用于说明和解释本申请实施例,并不用于限制本申请实施例。
本申请实施例一方面提供光学防伪元件,光学防伪元件能够呈现动感特征,动感特征被预先设计为一组在预设观察角度集合Ωv可见的动画帧的再现,动画帧包括图案区域和与图案区域形成光学对比度的背景区域;光学防伪元件具有大致平顺的漫反射性曲面,入射光被漫反射性曲面反射后可在不小于预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;漫反射性曲面包括被修饰的曲面区域和未被修饰的曲面区域,被修饰的曲面区域和未被修饰的曲面区域具有不同的反射特性,其中,被修饰的曲面区域与图案区域相对应;在漫反射性曲面被入射光照射时,被修饰的曲面区域共同呈现为动感特征的图案,未被修饰的曲面区域共同呈现为动感特征的背景,也即被修饰的反射面元共同再现出动感特征的图案,未被修饰的反射面元共同再现出动感特征的背景。
不同的反射特性是指被修饰的曲面区域与未被修饰的曲面区域在入射光照射时具有不同反射颜色、不同反射亮度、或者不同反射质感的一种或其组合。
在漫反射性曲面被入射光照射时,在每个动画帧对应的观察角度下,能够观察到该动画帧,其中,观察到的动画帧的图案是由被修饰的曲面区域呈现的,观察到的动画帧的背景是由未被修饰的曲面区域呈现的。
本申请实施例的“一组在预设观察角度集合Ωv可见的动画帧”是指观察角度与动画帧一一对应,一个观察角度对应一个动画帧。
本申请实施例动感特征实质上是指在观察角度改变时所出现的动感特征。原则上,观察角度可以为光源(即入射光)、元件和观察者三个要素中的一个或多个要素的角度。例如,在照明光源和人眼位置保持不变的情况下,将光学防伪元件或带有该光学防伪元件的物品拿在手中,通过前后或左右晃动元件,即改变光学防伪元件的角度,即可看到 所设计的动感特征。本申请为简化叙述,通过观察者的眼睛与所观察点的连线定义观察方向,由此定义观察角度。应注意,该定义不会本质影响或限制本申请实施例的任何相关内容。观察角度为三维空间参量,因而需要分解为至少两个角度加以准确描述。例如,可以采用俯仰角和方位角共同描述,也可以采用与观察方向与x、y、z三个坐标轴的夹角来共同描述。
动画帧的图案可设计为字母、数字、字符、符号或几何形状(尤其是圆形、椭圆形、三角形、矩形、六边形或星形等)。上述的动感特征泛指元件所呈现出的、人眼直接可见的设计图案的任意平动、转动、缩放、变形、隐现、阴阳转换等中一者,也可以为这些动感特征的任意组合。平动可以设计为设计图案在特定的一个方向平动,也可以设计为可以在多个方向平动,其平动方向与观察方向相关联。一种常用的组合特征为在设计动画帧图案位置发生变化的同时,其形状也发生变化,如圆形幻变为方形。动感特征可以具有图案的正交视差运动行为,即图案的运动方向始终与观察方向的改变相垂直,通过反直觉的现象进一步吸引观察者注意。动画帧图案的运动可通过双眼水平视差的原理产生漂浮在元件所在平面的上方或下方的立体感。图案还可包括呈现相同或不同的运动行为和/或相同或不同的漂浮高度或漂浮深度的多个子图案。尤其是,图案可包括至少第一曲线和第二曲线,当分别从第一或第二观察方向观察时,这些曲线分别呈现为位于第一或第二区域的中心位置处的第一或第二目标曲线。当防伪元件倾斜时,这两个曲线最好沿不同的(优选相反的)方向运动,从而产生特别动态的外观。应理解,采用同样的方式,防伪元件的图案还可包括不止两个曲线,当防伪元件倾斜时,这些曲线可沿相同或不同的方向运动。例如,字母数字字符串形式的曲线可交替地显现不同的运动行为,例如交替地漂浮在平面图案区的平面上方或下方,并且在倾斜时按照其漂浮高度运动。各种动感特征的具体原理可参照已有专利文本CN 102712207 A、CN 107995894 A、WO 2005/052650 A2等。本申请实施例中术语“图案”和“图案区域”可以相互替代。
动感特征在具体设计时可通过计算机软件,如数学计算软件、图案处理软件等生成的一组图片来代表。例如使用格式为bmp的位图,通过0-255的灰度值体现不同颜色的设计图案以及图案的共同背景。每一张图片对应着一个特定观察角度下呈现给人眼的视觉信息,称为所设计的动感特征的一帧动画。
预设观察角度集合Ωv是指当人眼的观察角度在该集合内变化时可以看到预设的全部动感特征。光学防伪元件可能将照明光反射至该集合之外,但这些反射光线可以与所 设计的动画特征没有联系,也可以为动感特征提供较为暗或黑的视觉信息。预设观察角度集合Ωv可以用方位角和俯仰角描述,例如,方位角可设计为0-360°,而俯仰角可以为0-35°或10-50°等等,即在人眼处于该圆锥形的区域都可以看到动感特征。该角度参数的设定取决于设计者的目的、观察者的所拥有的照明环境、观察习惯等等。
漫反射性曲面S区域可以使用俯仰角和方位角确定各处曲面区域的朝向。当然,也可以用其他参数确定曲面区域的朝向,特别是所采用的是彼此正交的参数,比如曲面区域的方向的两个正交分量。为产生足够精细的图案和连续变化的动感特征,漫反射性曲面S的波动特征长度,也就是相邻波峰和波谷间的平均距离,最好小于在人眼的识别能力,在明视距离该识别能力通常为约100μm,更近的距离则会提高该分辨能力。因而,相邻波峰和波谷间的平均距离不宜大于100μm。另一方面,过小的距离会对光产生明显的衍射,影响动感特征颜色稳定性。横向尺寸在5μm至100μm的距离则可在产生足够细腻的特征的同时,不产生明显的衍射彩虹色,横向尺寸可进一步优选为10μm至30μm。漫反射性曲面S中波峰和波谷间的平均距离可用下面的方法算出。在漫反射性曲面S中选取面积为A的正方形区域,找出该面积A内所包含的波峰数目N,并认为波峰和波谷数目基本相同,则上述的平均距离
本申请实施例中,漫反射性曲面S是连续且平顺的,即曲面无断点、裂缝,同时曲面没有棱角。满足一阶导数
都是基本连续的。例如,由方程S(x,y)=sin(2πx/p
x)sin(2πy/p
y)所定义的曲面在x、y方向都是连续且平顺的,P
x和P
y是在x和y方向的周期。实际制作的精度当然是有限的,漫反射性曲面S大致平顺即可达到本申请的目的。此外,实际使用并不要求漫反射性曲面S处处平顺,大部分区域,比如80%以上面积的曲面具有平顺特性,既可以达到本申请的目的。漫反射性曲面S可以至少在一个方向上是周期的,例如,漫反射性曲面S可以在x,y两个方向同时具有周期性,例如由以下表达式所确定的曲面:
S(x,y)=sin(2πx/p
x)sin(2πy/p
y)。
其中,p
x表示在x方向的周期,p
y表示在y方向的周期,x和y表示自变量。
当然,也可以只在一个方向上(例如x方向上)具有周期性,例如由以下表达式所确定的曲面,其同样满足平顺性的要求。
S(x,y)=sin(2πx/p
x)。
一般的,考虑到一个周期为P的函数可以使用傅里叶级数的方式进行分解,以一维 周期函数S(x)为例,
反过来,可以设定系数C
n,N,可利用下面的公式构造一个周期性函数,其中N为正整数。
对于非周期漫反射性曲面S,可利用计算机程序生成矩阵随机高度矩阵,此高度矩阵的数值代表漫反射性曲面S上的数个散点。通过将此矩阵一定差值处理或模糊处理,即可获得非周期性的漫反射性曲面SS。
漫反射性曲面S的主要作用是在所设定的预设观察角度集合Ωv产生均匀的反射光,与一般办公用纸所产生的漫反射的视觉印象类似。为达到该目的,各个曲面区域的朝向需在角度的连续集合Ωs内选取,朝向例如可以用方位角和俯仰角限定。角度连续集合Ωs的选择须将入射光均匀地至少反射至预设观察角度集合Ωv内,因而Ωs须覆盖一个由入射光方向ωi和Ωv共同确定的最小集合。等价的,反射性曲面S将入射光反射至角度集合Ωr,Ωr覆盖预设观察角度集合Ωv,即Ωv是Ωr的子集或真子集。特别地,Ωs设计为由入射光方向ωi和Ωv共同确定的最小集合,即Ωv与Ωr相同。例如,在入射光正入射至元件表面时,即元件处于xy平面,入射光沿着z方向,根据几何反射定律,Ωs的元素的方位角与Ωv的元素的方位角相同,而其元素的俯仰角为Ωv的元素的俯仰角一半。
为实现动感特征,需要根据每一幅动画帧的每一个像素点对漫反射性曲面进行修饰,从而改变在观察角度集合Ωv内均匀的反射光分布。漫反射曲面的大小应大于所有动画帧共同呈现时所占的面积的大小,以使得每幅动画帧都能无缩放的对应到漫反射性曲面上,从而动画帧的图案区域的每个像素都能在漫反射性曲面找到对应的位置点,该位置点将被修饰。
根据某一动画帧包含的图案区域所在的位置Pv和其被观察的角度ωv,找到需被修饰的曲面区域的位置Ps和角度ωs,例如可以每像素的寻找需要被修饰的曲面区域的位置和角度。原则上,Pv和Ps应为相同位置,且ωv,ωs和入射光角度ωi三者之间需满足几何光学的反射定律,即入射光、反射光线、曲面区域的法线处于同一平面,且入射角等于反射角。这里用ωs=f(ωv,ωi)表示三者存在定量关系,具体的计算公式在一般光学教科书上均可查到,例如玻恩的《光学原理:光的传播、干涉和衍射的电磁理论》。实际 设计中,当Pv=Ps时,该位置的曲面区域的角度ωs可能不会恰好与ωv和ωi满足几何反射定律。因此,可在一定的位置范围、一定的角度范围内修饰曲面区域,即:
Ps∈(Pv-ΔP,Pv+ΔP)
ωs∈(f(ωv,ωi)-Δω,f(ωv,ωi)+Δω)
其中,位置偏差ΔP,角度偏差Δω的选择根据曲面区域尺寸、人眼对角度和尺寸的分辨率、所设计的动感特征具体确定,其原则是能够找到至少一个应修饰的曲面区域,同时与设计图案不产生人眼可分别的差别。一般位置偏差ΔP小于100μm,优选为小于50μm,角度偏差Δω定义为被修饰的曲面区域的法线方向与图案预设观察角度所对应的曲面区域的法线方向夹角,角度偏差Δω应小于3°,优选为小于0.5°。
在具体执行时,可以将每一个动画帧像素化,将漫反射性曲面像素化。在可选情况下,也可以仅对每一个动画帧的图案区域进行像素化。像素化的本质就是将动画帧划分成例如N×M个小区域,每个小区域的所占面积例如可以非常小。类似的漫反射性曲面经像素化后划分成的小区域也可以非常小。例如,本申请实施例每个小区域的宽度可以为0.5μm至10μm,优选为2μm至4μm,相应的,每个小区域的长度可以为0.5μm至10μm,优选为2μm至4μm。
进一步可以确定每一个动画帧的第一方位角和第一俯仰角,每一个动画帧一一对应一个特定的观察角度,因而第一方位角和第一俯仰角可以根据动画帧的观察角度被确定。本申请实施例中,观察角度是一个在直角坐标系里的方向矢量。方向矢量和xy平面的夹角定义为俯仰角(也可以说成是与z轴夹角的余角)。把方向矢量投影到xy平面上形成投影矢量,该投影矢量和x轴的夹角定义为方位角。
进一步可以确定漫反射性曲面的各像素的第二方位角和第二俯仰角,第二方位角和第二俯仰角根据漫反射性曲面的像素处的法向量确定。漫反射性曲面中,像素的方位角可以定义为该像素处法向量与x轴的夹角,俯仰角可以定位该像素处法向量与z轴的夹角。本申请实施例中定义的xyz坐标中,xy平面为光学防伪元件所在平面,x轴可以为光学防伪元件的纵向方向,y轴可以为光学防伪元件的横向方向,z轴可以为与光学防伪 元件垂直的轴。
针对一组动画帧中的每一个动画帧可以执行以下步骤:在漫反射性曲面的与动画帧中的图案区域的像素相对应的位置处,寻找与动画帧的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素,从而在漫反射性曲面中形成与动画帧的图案区域相对应的区域。例如,可以同比例的将一组动画帧垂直投影在漫反射性曲面上,从而可以确定出漫反射性曲面上与每个动画帧中的每个像素相对应的位置。寻找与动画帧的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素可以包括:在漫反射性曲面的与动画帧中的图案区域的像素的预设距离范围内,寻找与第一方位角之间的角度差在第一预设角度差范围内的第二方位角、与二分之一的第一俯仰角之间的角度差在第二预设角度差范围内的第二俯仰角对应的像素。可选地,在俯仰角很小的情况下,方位角的差别变得不再重要。因此,在俯仰角比较小的情况下,可以不考虑方位角,仅在预设距离范围内,寻找与二分之一的第一俯仰角之间的角度差在第二预设角度差范围内的第二俯仰角对应的像素。预设距离范围是指与动画帧中的图案区域的像素所在位置之间的距离小于100μm,优选小于50μm。第一预设角度差范围是指与第一方位角之间的角度差小于3°,优选为小于0.5°。第二预设角度差范围是指与二分之一的第一俯仰角之间的角度差小于3°,优选为小于0.5°。针对图案区域的一个像素,可能会在漫反射性曲面中找到一个或多个符合条件的像素,可以对这一个或多个符合条件的像素均进行修饰。在漫反射性曲面中找到与动画帧的图案区域的每个像素相匹配的像素之后,这些相匹配的像素就形成与动画帧的图案区域相对应的区域。对在漫反射性曲面中形成的与每个动画帧的图案区域相对应的区域进行修饰,即可形成被修饰的曲面区域。
对曲面区域的修饰可以在被修饰的曲面区域增加次级结构,该次级结构的特征尺寸明显小于曲面区域的特征尺寸,因而可以沿着曲面区域的走向铺展在曲面区域表面。漫反射性曲面的曲面区域的特征尺寸可以由相邻波峰和波谷之间的平均距离来表征。次级结构的横向特征尺寸为0.2μm至5μm,对可见光可产生衍射作用或吸收作用。吸收作用可通过表面等离子共振吸收的原理,通过亚波长尺度的光栅结构吸收特定频率集合的入射光,从而改变反射光的颜色,同时保持原有的反射方向。通常当亚波长结构的深度比较深时,如300nm至700nm的可在更广泛的频率集合内产生有效的吸收,从而明显降低该方向的反射光的亮度,即该亚波长结构成为光学吸收或光学黑结构。
被修饰的曲面区域在修饰前可整体带有次级结构,在观察角度集合Ωv内产生均匀 的反射光分布的同时,并提供特定的颜色或亮度特征。因而,对曲面区域的修饰可以将被修饰的曲面区域的局部或整体变得光滑。例如去除被修饰的曲面区域的次级结构,使之对可见光全波段产生较高反射率的镜面反射。可选地,可以设置未被修饰的曲面区域的至少一部分为光滑的或带有次级结构的。
对曲面区域的修饰可以是将被修饰的曲面区域变得平坦,从而被修饰的曲面区域只能将入射光反射至特定一个反向。在其他观察角度下,该修饰区域均不提供或只提供很少的反射光,从而产生较其他区域更暗或者更黑的视觉感知。
对曲面区域的修饰可以是调整被修饰的曲面区域的角度,从而被修饰的曲面区域将所有入射到被修饰的曲面区域的光线反射至超出预设观察角度集合Ωv的方向。一般将曲面区域的俯仰角增大并超过一个由入射光方向ωi和Ωv共同确定的最小集合,即可将入射光反射至超出Ωv所确定的集合。该被修饰的曲面区域不提供或只提供很少的反射光,从而产生较其他区域更暗或者更黑的视觉感知。
为产生足够对比度的图案,被修饰的曲面区域所在的表面或与被修饰的曲面区域所在的表面相对的表面(例如未被修饰的曲面区域)可具有镀层或涂层。这包括反射增强涂层(尤其是金属化层)、反射增强镀层、反射油墨层、吸收油墨层、高折射率材料涂层、高折射率材料镀层。反射增强涂层、镀层或反射油墨层优选具有色移效果,即在不同观察角度下具有颜色的色调变化,例如采用法布里波罗干涉结构。可替代地,反射区域和曲面区域也可压印在反射油墨层或吸收油墨层中。
对曲面区域的修饰可以是将被修饰的曲面区域较周边未被修饰的曲面区域形成凸起或凹陷;或者对曲面区域的修饰可以是被修饰的曲面区域的镀层或涂层厚度不同于未被修饰的曲面区域。例如,在被修饰的曲面区域具有反射性镀层、涂层或油墨,同时在未被修饰的曲面区域没有反射性镀层、涂层或油墨;或者在被修饰的曲面区域没有反射性镀层、涂层或油墨,同时在未被修饰的曲面区域具有反射性镀层、涂层或油墨。
对曲面区域的修饰可以是上述多种修饰方式的串行方式组合使用。比如,在被修饰的曲面区域形成较未被修饰的曲面区域低的凹陷,然后在凹陷中增加次级结构,最后在将次级结构区域的反射性镀层去除(即与未被修饰的曲面区域的反射性镀层具有不同厚度);或者,在被修饰的曲面区域形成较未被修饰的曲面区域低的凹陷,并在凹陷里填充颜色油墨,其厚度明显大于未被修饰的曲面区域的油墨的厚度。对曲面区域的修饰可以是多种修饰方式的并行方式组合使用。比如,在被修饰的曲面区域的一部分形成平坦 的凹陷,并在该被修饰的曲面区域的另一部分沿着曲面区域的朝向增加次级结构。对曲面区域的修饰可以为以上修饰方式的串行组合方式和并行组合方式的再次组合使用。
本申请实施例中,根据所产生图案的可见程度,修饰区域的宽度为0.5μm至20μm,优选为2μm至10μm。被修饰的曲面区域较未被修饰的曲面区域具有不同反射颜色、不同反射亮度、不同反射质感的一种或组合。
光学防伪元件在观察角度集合Ωv内,被修饰的曲面区域共同呈现为动画帧的图案,未被修饰的曲面区域共同呈现为动画帧的背景。图案区域较背景区域具有不同的光学对比度,具体可为人眼可见的不同颜色、不同亮度、不同质感的一种或组合。
相应的,本申请实施例还提供一种用于光学防伪元件的设计方法,设计方法可以包括:设计一动感特征,动感特征为一组在预设观察角度集合Ωv可见的动画帧,动画帧包括图案区域和与图案区域形成光学对比度的背景区域;设计用于光学防伪元件的大致平顺的漫反射性曲面,使得入射光被漫反射性曲面反射后可在不小于预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;基于一组动画帧的各动画帧的观察角度,对与各动画帧的图案区域相对应的区域进行修饰以形成被修饰的曲面区域,使得被修饰的曲面区域与未被修饰的曲面区域具有不同的反射特性,在漫反射性曲面被入射光照射时,被修饰的曲面区域共同呈现为动感特征的图案,未被修饰的曲面区域共同呈现为动感特征的背景。
动感特征在具体设计时可通过计算机软件,如数学计算软件、图案处理软件等生成的一组图片来代表。例如使用格式为bmp的位图,通过0-255的灰度值体现不同颜色的设计图案以及图案的共同背景。每一张图片对应着一个特定观察角度下呈现给人眼的视觉信息,称为所设计的动感特征的一帧动画。本申请实施例的用于光学防伪元件的设计方法的具体工作原理及益处可以参考本申请实施例的关于光学防伪元件的描述,这里将不再赘述。
相应的,本申请实施例还提供一种使用本申请任意实施例的光学防伪元件的防伪产品。防伪产品例如可以是防伪线、防伪条、防伪标等形式。本申请实施例还提供一种具有本申请任意实施例的防伪元件或本申请任意实施例的防伪产品的数据载体,可以将防伪元件或防伪产品布置在数据载体的不透明区中、以及数据载体中的透明窗口区或贯通开口内或其上方。数据载体尤其可以是有价文件,例如钞票(尤其是纸质钞票、聚合物材料钞票或薄膜复合材料钞票)、股票、权证、证书、票券、支票、高价值的入场券, 但是也可以是识别卡,例如***、银行卡、现金卡、授权卡、个人身份证、或护照的个人信息页等。
下面将结合附图对本申请实时提供的光学防伪元件及其制作方法进行进一步的描述。
图1为光学防伪元件的漫反射性曲面区域对入射光的漫反射作用示意图。光学防伪元件1所在平面定义为xy平面,漫反射性曲面S由多个平顺连接的曲面区域3构成。本申请实施例中平顺连接指被连接的两个面的一阶导数是连续的,也就是说没有连接处但连上了,没有断裂并且也没有楞。曲面区域3能够具有凸起和凹陷。在图1中,光学防伪元件1带有基材6,漫反射性曲面S位于基材的一侧。然而基材6的存在是加工过程的需要,其可以不属于光学防伪元件1本身的一部分。基材6可以作为光学防伪元件1所形成的防伪产品的一部分。当然,基材6在防伪产品中也可以被去掉,例如烫印产品中,结构层被转移到其他载体中,而基材6不成为防伪产品的一部分。基材6不成为光学防伪元件1的必要组成部分。入射光4入射至基材6带有漫反射性曲面S的一侧,入射光4经漫反射性曲面S的反射作用,形成多个不同方向的反射光线5。通过控制多个曲面区域3的角度(角度例如由方位角和俯仰角限定)分布,使得基本均匀的漫反射视觉效果覆盖预定的动感特征的预设观察角度集合Ωv。为简化叙述并不失一般性,入射光4的方向设置为z方向,其是与xy平面垂直的方向。而集合Ωv的元素的方位角预定为0°-360°,俯仰角预定为0°-35°。据此,可将漫反射性曲面的波峰和波谷间的平均距离控制在20μm至50μm的范围内,而纵向高度设置为0μm至10μm,从而由漫反射性曲面S将入射光4反射至角度集合Ωr,Ωr能够覆盖预设观察角度集合Ωv。由于实际设计中通常采用有限的数值来代表连续性曲面,本申请的覆盖具体是指集合Ωv中任何一个元素都可以在Ωr中找到与之足够接近的对应元素,例如二者之间的夹角不超过1°。实际设计中反射性平顺曲面应至少包含3000个波峰和波谷,优选为50000个以上,从而产生足够细腻和均匀的反射光分布。图1仅为展示光学防伪元件的漫反射性曲面对入射光可产生漫反射作用,并未涉及具体动感特征以及对曲面区域的修饰方式。
为进一步说明漫反射性曲面S可采用的具体形式,图2举例了一种周期性的漫反射性曲面设计方式。采用解析方程:
S(x,y)=sin(2πx/p
x)+sin(2πy/p
x)+3sin(2πx/p
x)sin(2πy/p
y)
其中,Px和Py是在x和y方向的周期,可设置Px=20μm,Py=30μm。该式可制 造一个在x和y方向都具有周期性的平顺的漫反射性曲面。可根据需要,通过调整漫反射性曲面S的整体起伏高度来整体调节漫反射性曲面各个区域的俯仰角。正弦和余弦函数都是无限次可求导的,因而方程S(x,y)完全满足连续和平顺的要求。设F(x,y,z)=z-S(x,y)=0,漫反射性曲面S上任意一像素点(x
0,y
0,z
0)的法线方程和法向量
可分别由以下公式算出:
(x-x
0)/F
x(x
0,y
0,z
0)=(y-y
0)/F
y(x
0,y
0,z
0)=(z-z
0)/F
z(x
0,y
0,z
0)
这里,Fx表示函数F(x,y,z)对x的一阶导数,Fy表示函数F(x,y,z)对y的一阶导数,Fz表示函数F(x,y,z)对z的一阶导数。
通过法向量可以直接得出(x
0,y
0,z
0)处曲面区域的方位角φ(定义为法向量与x轴的夹角)和俯仰角θ(定义为法向量与z轴的夹角):
tan(φ)=F
y/F
x|(x
0,y
0,z
0)。
图3举例了一种非周期性的漫反射性曲面设计方式。对于非周期性的漫反射性曲面S,一种方法是利用计算机程序生成矩阵随机高度矩阵,此高度矩阵的数值代表漫反射性曲面S上的数个散点。通过将此矩阵一定差值处理或模糊处理,即可获得非周期的漫反射性曲面S。差值处理可采用双线性插值、使用像素区域关系进行重采样、4×4像素邻域的双三次插值、或8×8像素邻域的Lanczos插值等方式,而模糊处理可采用平均模糊、散焦模糊、运动模糊、或高斯模糊等方式。利用差值处理或模糊处理可保证高度之间不存在陡变和断裂,因此保证漫反射性曲面的平顺特性,即一阶导数是基本连续的。随机高度可采用伪随机数生成,伪随机数是看起来随机但是由确定性算法计算出的数字串,因此在严格意义上说,它们不是真正的随机数。不过,伪随机数被广泛使用,因为伪随机选取的统计特性(例如各个数字的均等概率或连续数字的统计独立性)通常足以满足实际用途的要求,并且与真正的随机数不同的是,伪随机数易于通过计算机产生。
依据构成动感特征的动画帧,对于漫反射的反射区域的特定曲面区域进行修饰,从而产生局部差别的反射特性。设定入射光角度ωi为沿着z轴方向,图4和图5提供两个实施例说明如何确定要被修饰的曲面区域。
图4为一个根据动画帧确定要被修饰的曲面区域的实施例。图4的两个表格分别表示局部曲面区域的俯仰角和方位角。因离散数据采样密度有限,图4的俯仰角和方位角 的数据未明显体现漫反射性曲面S的平顺特性,这不影响本实施例对如何利用动画帧确定待修饰曲面区域的原理说明。
如图4所示,7为描述的动感特征的一个动画帧,该动画帧定义为在俯仰角=0°、方位角=0°的方向被观察到。71是该动画帧的图案区域,而72为该动画帧的背景区域。71与72具有人眼可见的光学对比度。漫反射性曲面S上与该动画帧7对应的反射区域21的大小至少不小于动画帧7所在的区域大小,从而可完整的呈现动画帧7的视觉信息。以图案区域71上的任意一点Pv(也可以认为是任意一个像素点)为例,在反射区域21中确定Pv的对应点。在反射区域21中,以Pv为中心点,在ΔP的范围内寻找俯仰角=0°或与其的偏差小于Δω的曲面区域。在俯仰角很小的情况下,方位角的差别变得不再重要,因此这里不对方位角进行考虑。合适的控制ΔP和Δω的大小,总可以在反射区域21中找到任意一点Pv的对应点,即找到要被修饰的曲面区域。例如,曲面区域相邻的波峰波谷之间的平均距离为30μm,设定ΔP=60μm,Δω=1°,可在反射区域21中Pv点的右下方找到点(0.4°,75.2°),对该点相应的曲面区域的修饰可在动画帧7的Pv点产生预计的视觉对比度。
图5为另一个根据动画帧确定要被修饰的曲面区域的实施例。图5的两个表格分别表示局部曲面区域的俯仰角和方位角。因离散数据采样密度有限,图5的俯仰角和方位角的数据未明显体现曲面S的平顺特性,这不影响本实施例对如何利用动画帧确定待修饰曲面区域的原理说明。
如图5所示,在动画帧8中,81是该动画帧8的图案区域,而82为该动画帧8的背景区域。图案区域81与背景区域82具有人眼可见的光学对比度。图案区域81相对于上述图4中的图案区域71有位置的变化,且动画帧8定义为在俯仰角=20°、方位角=90°的方向被观察到。漫反射性曲面S上与该动画帧8对应的反射区域22的大小至少不小于动画帧8的所在的区域大小,从而可完整的呈现动画帧8的视觉信息。以图案区域81上的任意一点Pw(也可以认为是任意一个像素点)为例,在反射区域22中确定Pw的对应点。在反射区域22中,以Pw为中心点,在ΔP的范围内寻找与角度(俯仰角=10°,方位角=90°)所确定的曲面区域相同或角度偏差小于Δω的曲面区域。合适的控制ΔP和Δω的大小,总可以在反射区域22中找到要被修饰的曲面区域。例如,曲面区域相邻的波峰波谷之间的平均距离为30μm,设定ΔP=60μm,Δω=1°,可在反射区域22中Pw点的附近找到点(10.1°,92.2°)、(9.8°,89.7°),对该两点分别相应的曲面区域的修饰可在 动画帧8的Pw点产生预计的视觉对比度。
对曲面区域的修饰可采用多种方式。图6中被修饰的曲面区域31的局部或整体被特定方式修饰,从而产生与未被修饰的曲面区域32不同的反射特性。9为修饰方式的举例。其中:
如图6所示,91表示曲面区域的修饰是将被修饰的曲面区域较周边(例如未被修饰的曲面区域)形成凹陷,凹陷的深度在0.5μm至3μm内选择,并与修饰区域的宽度相关。同时,对曲面区域的修饰可以是将被修饰的曲面区域变得平坦,从而被修饰的曲面区域只能将入射光反射至特定的一个反向,在其他观察角度下,该被修饰的曲面区域均不提供或只提供很少的反射光,从而产生较其他区域更暗或者更黑的视觉感知。
如图6所示,92表示对曲面区域的修饰可以在被修饰区域增加次级结构,该次级结构的特征尺度明显小于曲面区域的尺寸,因而可以沿着曲面区域的朝向铺展在曲面区域表面。次级结构的横向特征尺寸为0.2μm至5μm,对可见光可产生衍射作用或吸收作用。吸收作用可通过表面等离子共振吸收的原理,通过亚波长尺度的光栅结构吸收特定频率集合的入射光,从而改变反射光的颜色,同时保持原有的反射方向。通常当亚波长结构的深度比较深时,如300nm至700nm的可在更广泛的频率集合内产生有效的吸收,从而明显降低该方向的反射光的亮度,即该亚波长结构成为光学吸收或光学黑结构。
如图6所示,93表示被修饰的曲面区域在修饰前可整体带有次级结构,在观察角度集合Ωv内产生均匀的反射光线分布的同时,并提供特定的颜色或亮度特征。因而,对曲面区域的修饰可以将被修饰的曲面区域变得光滑,即去除要被修饰的曲面区域的次级结构,使之对可见光全波段产生较高反射率的镜面反射。
如图6所示,94表示为产生足够对比度的图案,被修饰的曲面区域所在的表面或与被修饰的曲面区域所在的表面相对的表面(例如未被修饰的曲面区域)可具有镀层或涂层。这包括反射增强涂层(尤其是金属化层)、反射增强镀层、反射油墨层、吸收油墨层、高折射率材料涂层、高折射率材料镀层。反射增强涂层、镀层或反射油墨层优选具有色移效果,即在不同观察角度下具有颜色的色调变化,例如采用法布里波罗干涉结构,例如Cr(5nm)/MgF
2(500nm)/Al(50nm)结构。可替代地,反射区域和曲面区域也可压印在反射油墨层或吸收油墨层中。
对曲面区域的修饰可以是被修饰的曲面区域的镀层或涂层厚度不同于未被修饰的曲面区域。例如,在被修饰的曲面区域具有反射性镀层、涂层或油墨,同时在未被修饰 的曲面区域没有反射性镀层、涂层或油墨;或者在被修饰的曲面区域没有反射性镀层、涂层或油墨,同时在未被修饰的曲面区域具有反射性镀层、涂层或油墨。
如图6所示,95表示对曲面区域的修饰可以是调整被修饰的曲面区域的角度,从而将入射光反射至超出预设观察角度集合Ωv的方向。一般将曲面区域的俯仰角增大并超过一个由入射光方向ωi和Ωv共同确定的最小集合,即可将入射光反射至超出Ωv所确定的集合。该被修饰的曲面区域不提供或只提供很少的反射光线,从而产生较其他区域更暗或者更黑的视觉感知。
如图6所示,96表示对曲面区域的修饰可以是多种修饰方式的串行方式组合使用。比如,在被修饰的曲面区域形成较周边区域低的凹陷,然后在凹陷中增加次级结构,最后在将次级结构区域的反射性镀层去除(即与未被修饰的曲面区域具有不同厚度);或者在被修饰的曲面区域形成较周边区域低的凹陷,并在凹陷里填充颜色油墨,其厚度明显大于未被修饰的曲面区域的油墨的厚度。
如图6所示,97表示对曲面区域的修饰可以是多种修饰方式的并行方式组合使用。比如,在被修饰的曲面区域的一部分形成平坦的凹陷,并在该被修饰的曲面区域的另一部分沿着曲面区域的朝向增加次级结构。对曲面区域的修饰可以为以上修饰方式的串行组合方式和并行组合方式的再次组合使用。
被修饰部分可以存在于被修饰的曲面区域的局部或整体。对于理想的平面型曲面区域,被修饰部分将等于该被修饰的曲面区域。而对于弯曲的曲面区域,被修饰部分将存在于该被修饰的曲面区域的局部。修饰区域的宽度为0.5μm至10μm,优选为2μm至4μm。被修饰的曲面区域较未被修饰的曲面区域具有不同反射颜色、不同反射亮度、不同反射质感的一种或组合。
图6中漫反射性曲面S的一部分曲面区域31和32分别将入射光4反射至方向51和52。其中,被修饰的曲面区域31的反射光线产生动画帧的图案,即被修饰的曲面区域共同呈现为动画帧的图案;未被修饰的曲面区域32的反射光线产生动画帧的背景,即未被修饰的曲面区域共同呈现为动画帧的背景。图案区域较背景区域具有不同的光学对比度,具体可为人眼可见的不同颜色、不同亮度、不同质感的一种或组合。
图7示出了钞票10的示意图,该钞票10具有本申请的光学防伪元件,该光学防伪元件是以窗口防伪线101的形式嵌入在钞票10之内。另外,还可以以贴标102的方式使用该光学防伪元件,并可以对钞票10形成开孔区域103,便于透光观察。应理解,本申 请不局限于防伪线和钞票,而是可用于各种防伪产品,例如用在货物和包装上的标签中,或者用在防伪文件、身份证、护照、***、保健卡等之中。在钞票和类似文件中,除了防伪线和贴标之外,例如还可使用较宽的防伪条或转印元件。
本申请实施例提供了一种存储介质,其上存储有程序,该程序被处理器执行时实现本申请任意实施例的用于光学防伪元件的设计方法。
本申请实施例提供了一种处理器,处理器用于运行程序,其中,程序运行时执行本申请任意实施例的用于光学防伪元件的设计方法。
本申请实施例提供了一种电子设备,设备包括处理器、存储器及存储在存储器上并可在处理器上运行的程序,处理器执行程序时实现本申请任意实施例的用于光学防伪元件的设计方法。
本申请还提供了一种计算机程序产品,当在数据处理设备上执行时,适于执行初始化有本申请任意实施例的用于光学防伪元件的设计方法步骤的程序。
本领域内的技术人员应明白,本申请的实施例可提供为方法、***、或计算机程序产品。因此,本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且,本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请实施例的方法、设备(***)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器,使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中,使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品,该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上,使得在计算 机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理,从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
在一个典型的配置中,计算设备包括一个或多个处理器(CPU)、输入/输出接口、网络接口和内存。
存储器可能包括计算机可读介质中的非永久性存储器,随机存取存储器(RAM)和/或非易失性内存等形式,如只读存储器(ROM)或闪存(flash RAM)。存储器是计算机可读介质的示例。
计算机可读介质包括永久性和非永久性、可移动和非可移动媒体可以由任何方法或技术来实现信息存储。信息可以是计算机可读指令、数据结构、程序的模块或其他数据。计算机的存储介质的例子包括,但不限于相变内存(PRAM)、静态随机存取存储器(SRAM)、动态随机存取存储器(DRAM)、其他类型的随机存取存储器(RAM)、只读存储器(ROM)、电可擦除可编程只读存储器(EEPROM)、快闪记忆体或其他内存技术、只读光盘只读存储器(CD-ROM)、数字多功能光盘(DVD)或其他光学存储、磁盒式磁带,磁带磁磁盘存储或其他磁性存储设备或任何其他非传输介质,可用于存储可以被计算设备访问的信息。按照本文中的界定,计算机可读介质不包括暂存电脑可读媒体(transitory media),如调制的数据信号和载波。
还需要说明的是,术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含,从而使得包括一系列要素的过程、方法、商品或者设备不仅包括那些要素,而且还包括没有明确列出的其他要素,或者是还包括为这种过程、方法、商品或者设备所固有的要素。在没有更多限制的情况下,由语句“包括一个……”限定的要素,并不排除在包括要素的过程、方法、商品或者设备中还存在另外的相同要素。
以上仅为本申请的实施例而已,并不用于限制本申请。对于本领域技术人员来说,本申请可以有各种更改和变化。凡在本申请的精神和原理之内所作的任何修改、等同替换、改进等,均应包含在本申请的权利要求范围之内。
Claims (24)
- 一种光学防伪元件,其特征在于,所述光学防伪元件能够呈现动感特征,所述动感特征被预先设计为一组在预设观察角度集合Ωv可见的动画帧的再现,所述动画帧包括图案区域和与所述图案区域形成光学对比度的背景区域;所述光学防伪元件具有大致平顺的漫反射性曲面,入射光被所述漫反射性曲面反射后在不小于所述预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;所述漫反射性曲面包括被修饰的曲面区域和未被修饰的曲面区域,所述被修饰的曲面区域和所述未被修饰的曲面区域具有不同的反射特性,其中,所述被修饰的曲面区域与所述图案区域相对应;在所述漫反射性曲面被所述入射光照射时,所述被修饰的曲面区域共同呈现为所述动感特征的图案,所述未被修饰的曲面区域共同呈现为所述动感特征的背景。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述漫反射性曲面至少在一个方向上是周期性的。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述漫反射性曲面至少在一个方向上是非周期性的。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述漫反射性曲面的相邻波峰和波谷之间的平均距离为5μm至100μm,优选为10μm至30μm。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述漫反射性 曲面的相邻波峰和波谷之间的平均高度差为1μm至10μm。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述未被修饰的曲面区域的至少一部分为光滑的或是带有次级结构的。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述被修饰的曲面区域通过以下多种方式中的一者或多者被修饰:使所述被修饰的曲面区域增加次级结构;使所述被修饰的曲面区域变得光滑;使所述被修饰的曲面区域变得平坦;使所述被修饰的曲面区域设置为与未被修饰的曲面区域相比具有凸起或凹陷;调整所述被修饰的曲面区域的角度,使得所述入射光被反射至超出所述预设观察角度集合Ωv的范围;或者使所述被修饰的曲面区域的镀层或涂层的厚度调整为不同于所述未被修饰的曲面区域。
- 根据权利要求7所述的光学防伪元件,其特征在于,在所述被修饰的曲面区域通过所述多种方式中的两种或两种以上的方式被修饰的情况下,所述两种或两种以上的方式以并行组合和/或串行组合的方式存在。
- 根据权利要求6至8中任一项所述的光学防伪元件,其特征在于,所述的次级结构的横向特征尺寸为0.2μm至5μm。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述被修饰的曲面区域的宽度为0.5μm至20μm,优选为2μm至10μm。
- 根据权利要求1所述的光学防伪元件,其特征在于,所述不同的反射特性是指所述被修饰的曲面区域与所述未被修饰的曲面区域在所述入射光照射时具有不同反射颜色、不同反射亮度、或者不同反射质感的一种或其组合。
- 一种用于光学防伪元件的设计方法,其特征在于,所述设计方法包括:设计一动感特征,所述动感特征为一组在预设观察角度集合Ωv可见的动画帧的再现,所述动画帧包括图案区域和与所述图案区域形成光学对比度的背景区域;设计用于所述光学防伪元件的大致平顺的漫反射性曲面,使得入射光被所述漫反射性曲面反射后可在不小于所述预设观察角度集合Ωv的范围内形成大致均匀的亮度分布;基于所述一组动画帧的各动画帧的观察角度,对与所述各动画帧的所述图案区域相对应的区域进行修饰以形成被修饰的曲面区域,使得所述被修饰的曲面区域与未被修饰的曲面区域具有不同的反射特性,在所述漫反射性曲面被所述入射光照射时,所述被修饰的曲面区域共同呈现为所述动感特征的图案,所述未被修饰的曲面区域共同呈现为所述动感特征的背景。
- 根据权利要求12所述的设计方法,其特征在于,所述漫反射性曲面至少在一个方向上是周期性的。
- 根据权利要求12所述的设计方法,其特征在于,所述漫反射性曲 面至少在一个方向上是非周期性的。
- 根据权利要求12所述的设计方法,其特征在于,所述漫反射性曲面的相邻波峰和波谷之间的平均距离为5μm至100μm,优选为10μm至30μm。
- 根据权利要求12所述的设计方法,其特征在于,所述漫反射性曲面的相邻波峰和波谷之间的平均高度差为1μm至10μm。
- 根据权利要求12所述的设计方法,其特征在于,基于所述一组动画帧的各动画帧的观察角度,对与所述各动画帧的所述图案区域相对应的区域进行修饰以形成被修饰的曲面区域,包括:将所述一组动画帧中的每一个动画帧和所述漫反射性曲面进行像素化;确定所述每一个动画帧的第一方位角和第一俯仰角,所述第一方位角和所述第一俯仰角根据所述动画帧的观察角度被确定;确定所述漫反射性曲面的各像素的第二方位角和第二俯仰角,所述第二方位角和第二俯仰角根据所述漫反射性曲面的像素处的法向量确定;针对所述一组动画帧中的每一个动画帧执行以下步骤:在所述漫反射性曲面的与所述动画帧中的图案区域的像素相对应的位置处,寻找与所述动画帧的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素,从而在所述漫反射性曲面中形成与所述动画帧的图案区域相对应的区域;以及对在所述漫反射性曲面中形成的与所述动画帧的图案区域相对应的区域进行修饰。
- 根据权利要求17所述的设计方法,其特征在于,在所述漫反射性 曲面与所述动画帧中的图案区域的像素相对应的位置处,寻找与所述图案区域的像素的第一方位角和第一俯仰角相匹配的第二方位角和第二俯仰角对应的像素,包括:在所述漫反射性曲面与所述动画帧中的图案区域的像素的预设距离范围内,寻找与所述第一方位角之间的角度差在第一预设角度差范围内的第二方位角、与二分之一的所述第一俯仰角之间的角度差在第二预设角度差范围内的第二俯仰角对应的像素。
- 根据权利要求18所述的设计方法,其特征在于,所述预设距离范围是指与所述动画帧中的图案区域的像素所在位置之间的距离小于100μm,优选小于50μm;和/或所述第一预设角度差范围是指与所述第一方位角之间的角度差小于3°,优选为小于0.5°;和/或所述第二预设角度差范围是指与所述第一俯仰角之间的角度差小于3°,优选为小于0.5°。
- 根据权利要求12或17所述的设计方法,其特征在于,对与所述各动画帧的所述图案区域相对应的区域进行修饰以形成被修饰的曲面区域,包括执行以下方式中的一者或多者:使所述被修饰的曲面区域增加次级结构;使所述被修饰的曲面区域变得光滑;使所述被修饰的曲面区域变得平坦;使所述被修饰的曲面区域设置为与未被修饰的曲面区域相比具有凸起或凹陷;调整所述被修饰的曲面区域的角度,使得所述入射光被反射至超出所述 预设观察角度集合Ωv的范围;或者使所述被修饰的曲面区域的镀层或涂层的厚度调整为不同于所述未被修饰的曲面区域。
- 根据权利要求12所述的设计方法,其特征在于,所述动感特征为平动、转动、缩放、变形、隐现、阴阳转换的一种或其组合;和/或所述光学对比度为人眼可见的不同颜色、不同亮度、不同质感的一种或其组合。
- 根据权利要求12所述的设计方法,其特征在于,所述被修饰的曲面区域的宽度为0.5μm至20μm,优选为2μm至10μm。
- 一种使用权利要求1至11中任一项所述的光学防伪元件的防伪产品。
- 一种数据载体,其特征在于,所述数据载体具有权利要求1至11中任一项所述的光学防伪元件,或者具有根据权利要求23所述的防伪产品。
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