JP2009139798A - Diffraction grating pattern and diffraction grating recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diffraction grating pattern which has an up-to-date visual image such that display color are changed in accordance with rotation of a substrate or illumination direction and can further raise the level of forgery prevention without impairing resolution and brightness, and to provide a diffraction grating recording medium. <P>SOLUTION: A pixel pattern structure which is arranged corresponding to pixels of an image expressed by arranging minute cells or dots made of a diffraction grating on the surface of a substrate is not a structure composed of single kind of grating angle and grating space of the diffraction grating but a structure composed of at least two kinds of them, in addition, the grating space is changed in conjugation with the grating angle, and hue and chroma of display color of the image are changed by rotating the substrate or the illumination direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a pixel pattern structure arranged corresponding to a pixel of an image expressed by arranging minute cells or dots made of a diffraction grating on a substrate surface has two or more types of internal structure of the pixel pattern. The present invention relates to a diffraction grating pattern and a diffraction grating recording medium having a color tone reversal capable of further enhancing forgery prevention, in which the hue and saturation of display colors change and the visual image is novel.

  The display composed of diffraction gratings has a directional gloss that cannot be expressed by ordinary printing technology, so it is intended for display applications and security for the purpose of preventing counterfeiting of credit cards, securities, cash vouchers, etc. It is widely used in products, and it is required to produce more diverse and highly original patterns.

  In response to such a demand, a display body having a diffraction grating pattern constituted by a collection of cell (dot) -like diffraction gratings is known.

  As a method for manufacturing a display body using a diffraction grating as a pixel, for example, a method proposed in Patent Document 1 is known. In this method, minute interference fringes (diffraction grating) due to two-beam interference of laser light are successively exposed on a photosensitive film while changing the pitch, direction, and light intensity.

  On the other hand, for example, in Patent Document 2 and Patent Document 3, an XY stage on which a planar substrate is placed is moved by using an electron beam exposure apparatus instead of laser light and under computer control. A method for producing a diffraction grating pattern by arranging a plurality of minute dots made of a diffraction grating on the surface has also been proposed.

  In these techniques described above, the grid angle, grid spacing, and cell size (or grid depth) are defined for each pixel, and an image is formed from a plurality of groups and continuous displacement. The internal structure of the pattern was a diffraction grating pattern consisting of a single component.

  If the internal structure of the pixel pattern is only a single component, in order to obtain a change in action for a certain operation, pixels are allocated by the number of stages of the change. Decrease is a problem.

  Conventionally, as a diffraction grating pattern, for example, in Patent Document 4, a relief type diffraction grating in which a plurality of minute cells (or dots) made of a diffraction grating are arranged on the surface of the same substrate and a reflection layer is formed on the entire surface. In such a diffraction grating pattern, a diffraction grating pattern has been proposed in which the direction of the diffraction grating approximates between adjacent cells and the direction of reflected diffracted light from the pattern changes continuously.

  Further, for example, in Patent Document 5, a plurality of small cells made of diffraction gratings are arranged on the substrate surface, and at least one of the spatial frequency of the diffraction grating, the direction of the diffraction grating, and the formation region of the diffraction grating changes. In this pattern, there is proposed a diffraction grating pattern characterized in that the pattern has a minute area composed of four or more kinds of diffraction gratings having different spatial frequencies with the same direction in each pattern. Has been.

However, in the diffraction grating patterns proposed in the cited document 4 and the cited document 5, the internal structure of the pixel pattern is composed of a single component diffraction grating pattern, and the combination of components assigned to individual pixels or multiple pixels. There is a problem that the resolution and brightness are lowered. In addition, the configuration of one pixel and one component makes the analysis relatively easy, and a similar product can be easily created by using an interference fringe recording method using a laser beam without using expensive equipment. It is.

  Further, in the diffraction grating recording medium in which a predetermined motif is expressed by the diffraction grating, both the first grating line facing the first direction and the second grating line facing the second direction are set in the same closed region. A diffraction grating recording medium recorded therein is proposed in Patent Document 6.

  The diffraction grating pattern in the diffraction grating recording medium proposed in Cited Document 6 has an internal structure composed of a plurality of components. However, there are two types of component configurations and the hybrid system is a multiple system. The components are assigned only by the grid angle, and the change in display color due to the change in the grid interval cannot be observed.

  As described above, the conventional diffraction grating pattern and the diffraction grating recording medium have a certain prevention effect against copying or the like. However, when the entire image is observed, there is a problem that the resolution and brightness are reduced and the visual image is extremely low. However, there is a problem that it is difficult to produce a more diverse and highly original pattern because it is limited and easily restricted by design (design).

The known literature is described below.
JP 60-156004 A JP-A-2-72320 US Pat. No. 5,058,992 JP-A-10-153702 JP 2000-352609 A JP-A-8-161449

  The present invention has been made in consideration of the above-described technical background, and without damaging the resolution or brightness of an image expressed by arranging minute cells or dots made of diffraction gratings, It is an object of the present invention to provide a diffraction grating pattern and a diffraction grating recording medium in which a visual image in which the display color of an image changes with rotation is novel, and forgery prevention can be further enhanced.

As a solution to achieve the above problems,
In the invention according to claim 1, the pixel pattern structure arranged corresponding to the pixel of the image expressed by arranging the minute cells or dots made of the diffraction grating on the substrate surface has the grating angle of the diffraction grating and The lattice spacing is not a single structure but is composed of at least two kinds of structures, and the lattice spacing is changed in conjunction with the lattice angle, and by rotating the substrate or the illumination direction, the hue of the display color of the image The diffraction grating pattern is characterized in that the saturation changes.

  The invention according to claim 2 is the diffraction grating pattern according to claim 1, wherein the hue or saturation of the display color of the image is reversed as the substrate or the illumination direction is rotated.

The invention according to claim 3 is characterized in that the hue or saturation of the display color of the image changes continuously with the rotation of the substrate or the illumination direction. It is.

  According to a fourth aspect of the present invention, the pixel pattern structure comprises two types of pixel patterns in which a rotation base point and an end point diffraction grating are interchanged, and a diffraction grating common to both pixels is arranged in a rotation region of a predetermined angle. 2. The diffraction grating pattern according to claim 1, wherein the hue of the display color of the image is reversed and the image forms a latent image at a predetermined angle of the rotation region.

  The invention according to claim 5 is a diffraction grating recording medium, wherein the diffraction grating pattern according to any one of claims 1 to 4 is arranged.

  According to the present invention, a substrate on which a diffraction grating pattern is formed because the internal structure of the pixel pattern is expressed by arranging minute cells (dots) made of a diffraction grating on the surface of the substrate. Or by rotating the illumination direction, the hue and saturation of the display color change without reducing the resolution and brightness, creating a more diverse and highly original pattern, creating a new visual image and preventing counterfeiting. The diffraction grating pattern and the diffraction grating recording medium can be provided.

  Hereinafter, the present invention will be described based on examples with reference to the drawings.

Conventional diffraction grating pattern and diffraction grating recording medium

  First, a conventional method for expressing a motif (showing the English letter “A”) as shown in FIG. 5A on a diffraction grating recording medium will be described. Motif pixel information as shown in FIG. 5B is prepared as image data corresponding to the motif shown in FIG. In the example shown here, pixels are arranged in 7 rows and 7 columns, and each pixel has a pixel value of “0” or “1”, which is information indicating a so-called binary image. Such information is general image data called so-called “raster image data”, and can be created by a normal drawing device. Alternatively, such motif pixel information can be obtained by taking in a design image drawn on a paper surface by a scanner device.

  FIG. 6 is an explanatory view illustrating an example of a conventional pixel pattern (diffraction grating pattern) and a diffraction grating recording medium, and explaining how the diffraction grating recording medium looks in each illumination direction.

  FIG. 6A is an explanatory diagram showing an enlarged pixel pattern. In the figure, as a pixel pattern, the diffraction grating has a spatial frequency (pitch) of D, and the ratio of the line width (L) and the space width (S) of the grating expressed in white and black is approximately 1: 1. Although the pixel pattern is exemplified, the present invention is not limited to this.

  Next, in the motif pixel information shown in FIG. 5B, the pixel pattern of FIG. 6A is associated with each pixel having a pixel value “1”. A pixel pattern is not associated with a pixel having a pixel value “0”. A pixel pattern is assigned to each pixel position thus associated. In other words, if the arrangement shown in FIG. 5 (b) is compared to a wall, the tiles shown in FIG. 6 (a) are pasted one by one in each area labeled “1” in the wall. It will be. As a result, this pixel pattern is finally recorded on the diffraction grating recording medium as shown in FIG. Although the motif shown in FIG. 5A is expressed as it is, each pixel is composed of a diffraction grating, and a visual effect as a diffraction grating can be obtained.

  Since the diffracted light obtained from the diffraction grating has directionality, it may or may not be observed depending on the observation direction. That is, as shown in FIG. 6 (c), the appearance of the diffraction grating recording medium in each illumination direction is observed with the motif shining in (c1), but the motif in (c2) and (c3), Neither background shines.

  FIG. 7 is an explanatory diagram illustrating how the diffraction grating recording medium looks in each illumination direction by exemplifying another example of a conventional pixel pattern (diffraction grating pattern) and a diffraction grating recording medium.

  FIG. 7A shows that all the diffraction gratings have a spatial frequency (pitch) of D, and the ratio of the line width (L) and the space width (S) of the grating expressed in white and black is almost equal. This is a pixel pattern in which a diffraction grating having a grating line arrangement angle of 0 ° (horizontal), which is 1: 1, and a diffraction grating having a grating line arrangement angle of 90 ° (vertical) are recorded in a multiplexed manner.

  This pixel pattern is finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 7C, the pixel is diffracted corresponding to angles in three directions, and the appearance of the diffraction grating recording medium in each illumination direction is observed with the motif shining in (c1). In (c2), the motif is shined and observed at an angle having the period of the intersection of the two types of lattices. In (c3), the motif is shined and observed as in (c1).

  FIG. 8 is an explanatory diagram illustrating the appearance of the diffraction grating recording medium in each illumination direction, illustrating another example of a conventional pixel pattern (diffraction grating pattern) and a diffraction grating recording medium.

  FIG. 8A shows that all the diffraction gratings have a spatial frequency (pitch) of D, and the ratio of the line width (L) and the space width (S) of the grating expressed in white and black is almost equal. It is a pixel pattern composed of concentric diffraction gratings of 1: 1.

  This pixel pattern is finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 8C, the pixel is diffracted corresponding to angles in all directions, and the appearance of the diffraction grating recording medium in each illumination direction is (c1), (c2), (c3). In both cases, the motif is shining and observed.

  FIG. 9 is an explanatory diagram illustrating another example of a conventional pixel pattern (diffraction grating pattern) and diffraction grating recording medium and explaining how the diffraction grating recording medium looks in each illumination direction.

  FIG. 9A shows that all the diffraction gratings have a spatial frequency (pitch) of D, and the ratio of the line width (L) and the space width (S) of the grating expressed in white and black is almost equal. A pixel pattern of a diffraction grating (P1) having a grating line arrangement angle of 0 ° (horizontal), which is 1: 1, and a diffraction grating (P2) having a grating line arrangement angle of 90 ° (vertical) can be allocated on the same medium. .

  The pixel patterns P1 and P2 are allocated on the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG. 9B.

Then, as shown in FIG. 9C, the appearance of the diffraction grating recording medium in each illumination direction by the combination of diffraction gratings having different angles is observed with the motif shining in (c1).
In 2), it does not shine with the motif and background. In (c3), the background is illuminated and observed.

  Here, as diffraction conditions, normal illumination conditions, that is, illumination of the diffraction grating cell with white light are considered. FIG. 10 is an explanatory diagram showing diffraction conditions when white light is incident on the diffraction grating cell at a specific angle.

  In holograms and diffraction gratings, diffracted light inevitably accompanies wavelength dispersion, so that an observer can view first-order diffracted light at a predetermined wavelength only from one specific direction. Therefore, as shown in FIG. 10, the first-order diffracted light dispersed for each wavelength is emitted, and the observed color changes to a rainbow color due to the viewpoint moving up and down (the direction of the grating vector of the diffraction grating) by the observer. On the upper side of the figure, the first-order diffracted light is 600 nm close to red, while on the lower side is 400 nm close to blue. In other words, the diffraction angle β in the above equation is not only a function of spatial frequency but also a function of wavelength.

  Furthermore, FIG. 11 illustrates still another example of a conventional pixel pattern (diffraction grating pattern) and a diffraction grating recording medium, and how the diffraction grating recording medium looks in each illumination direction will be described.

  In FIG. 11A, the spatial frequency (pitch) of the diffraction grating is different, and the ratio between the line width and the space width of the grating expressed in white and black is approximately 1: 1, and the pitch P1 (at the diffraction wavelength λ1). Corresponding pixel patterns and pitch P2 (corresponding to diffraction wavelength λ2) diffraction gratings are allocated on the same medium.

  The pixel patterns P1 and P2 are allocated on the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 11 (c), the appearance of the diffraction grating recording medium in each illumination direction by the combination of diffraction gratings having different grating pitches is observed. In (c1), the motif and the background are observed in different colors. In (c2) and (c3), neither the motif nor the background glows.

  In the conventional diffraction grating pattern and the diffraction grating recording medium obtained above, the internal structure of the pixel pattern is only a single component. When the entire image is observed, a decrease in resolution and brightness becomes a problem. In addition, the visual image is extremely limited, it is easy to be restricted by design (design), it is difficult to produce a more diverse and highly original pattern, and there is a certain prevention effect against copying etc. However, its prevention level is low.

Diffraction grating pattern and diffraction grating recording medium of the present invention

  Next, the diffraction grating pattern and the diffraction grating recording medium of the present invention will be described. In the diffraction grating pattern and the diffraction grating recording medium of the present invention, the pixel pattern structure arranged corresponding to the pixel of the image expressed by arranging minute cells or dots made of the diffraction grating on the substrate surface is diffracted. The lattice angle and the lattice interval of the lattice are not a single structure but at least two types of structures, and the lattice interval is changed in conjunction with the lattice angle, and the substrate or the illumination direction is rotated. It is characterized in that the hue and saturation of the display color change.

  The relationship between the diffraction grating pattern and the diffracted light is generally known to satisfy the following formula (1).

sin θ _out −sin θ _in = λ / d (1)
However, θ _out first-order diffracted light angle θ _in incident angle λ wavelength d grating pitch Therefore, it is understood that if the angle of the reproduction light source is fixed, the change in display color (diffraction wavelength) may be changed by changing the grating pitch. Therefore, if a grid with an arbitrary pitch is assigned to an arbitrary angle, the grid interval is changed in conjunction with the grid angle in the present invention, and the display is performed without losing resolution or brightness by rotating the substrate or the illumination direction. A diffraction grating pattern and a diffraction grating recording medium in which the hue and saturation of color change are obtained.

That is, for example, a diffraction grating pattern and a diffraction grating recording medium of the types shown in the following (1) to (4) can be provided.
(1) Switching type: a diffraction grating pattern and a diffraction grating recording medium in which the wavelength of the diffracted light is switched with the rotation of the substrate or the illumination direction by making the grating pitches of the diffraction gratings 2 non-identical.
(2) Continuous change type: By continuously changing the diffraction grating from the diffraction grating pitch at the base point angle to the diffraction grating pitch at the end point angle, the wavelength of the diffracted light continuously changes with the rotation of the substrate or illumination direction. Changing diffraction grating pattern and diffraction grating recording medium.
(3) Hue change and saturation change type: When the diffraction grating pitch is a single periodic structure, the wavelength of the diffracted light is a single, resulting in a primary color with high saturation, and the diffraction grating pitch has a plurality of periodic structures. A diffraction grating pattern and a diffraction grating recording medium approaching an achromatic color with low saturation because a plurality of wavelengths of diffracted light are generated and mixed.
(4) Color tone reversal and tuning type: Prepare a pair of pixels with the diffraction grating structure of the rotation base point and end point interchanged and apply them to the image character and the background respectively. To do. As a two-pair configuration, if a diffraction grating structure common to both pixels is applied to a part of the rotation region, the character and the background are synchronized by observation at that angle, so that the character outline disappears and a latent image state is established. Diffraction grating pattern and diffraction grating recording medium.

  Hereinafter, the diffraction grating pattern and the diffraction grating recording medium of the present invention will be described by way of specific examples. FIG. 1 is an explanatory diagram illustrating the appearance of a diffraction grating recording medium in each illumination direction by exemplifying the color tone change, switching type pixel pattern (diffraction grating pattern) and diffraction grating recording medium of the present invention. .

  FIG. 1A is an explanatory diagram showing an enlarged pixel pattern. A diffraction grating (P1) and a diffraction grating (P2) having grating pitches d1 (corresponding to wavelength λ1 of diffracted light) and d2 (corresponding to wavelength λ2 of diffracted light) having different diffraction grating pitches as shown in FIG. In the present invention, the diffraction grating angle is not limited to horizontal / vertical and orthogonal patterns.

  The pixel patterns P1 and P2 are allocated on the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 1C, the diffraction grating recording medium is viewed in each illumination direction in which the wavelength (color tone) of the diffracted light is switched with rotation. In (c1), the motif is λ1, the background Observed at λ2, observed in (c2) and (c3) by shining at an angle with the intersection of the two lattices of the motif and background as a period, and observed at λ2 and background λ1 in (c4) .

FIG. 2 illustrates the color change, continuous change type pixel pattern (diffraction grating pattern) and diffraction grating recording medium of the present invention, and explains the appearance of the diffraction grating recording medium in each illumination direction. FIG.

  FIG. 2A is an explanatory diagram showing an enlarged pixel pattern. As shown in the figure, a pixel pattern including diffraction gratings (P1) and diffraction gratings (P2) having different grating pitches d1, d2, d3, and d4 that are substantially concentric circles is illustrated.

  The pixel patterns P1 and P2 are allocated to the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 2 (c), the appearance of the diffraction grating recording medium in each illumination direction in which the color tone continuously changes corresponding to the angle change is as follows. In (c1), the motif is λ1 and the background λ2 In (c2), when d2 = d4, the motif and background have the same wavelength (λ2 = λ4), and the front surface is illuminated with uniform illumination. In (c3), the motif is observed at λ2 and background λ1. .

  FIG. 3 illustrates the saturation change, switching type pixel pattern (diffraction grating pattern) and diffraction grating recording medium of the present invention, and explains how the diffraction grating recording medium looks in each illumination direction. FIG.

  FIG. 3A is an explanatory diagram showing an enlarged pixel pattern. As shown in the figure, the grating angles are determined from diffraction gratings (P1) and diffraction gratings (P2) having different grating pitches d1 to d7 (corresponding to wavelengths λ1 to λ7 of diffracted light) composed of horizontal, vertical and orthogonal patterns. In the present invention, the lattice angle is not limited to the horizontal / vertical pattern and the orthogonal pattern. Further, the number of types of the grid pitch d for the purpose of color mixing may be at least two, and is not limited to the seven types shown in FIG. 3 (a), and the displacement of the grid pitch d particularly has continuity and regularity. do not need.

  The pixel patterns P1 and P2 are assigned to the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG.

  Then, as shown in FIG. 3 (c), the saturation change is switched corresponding to the change in angle, and the appearance of the diffraction grating recording medium in each illumination direction is as follows. In (c1), the motif is the primary color and the background is the mixed color. Observed in (white), observed in (c2) and (c3) by shining intermittently at angles with the period of the lattice points of the motif and background, and in (c4) the motif is mixed color (white) and the background is Observed in primary colors.

  FIG. 4 illustrates the saturation change, continuous change type pixel pattern (diffraction grating pattern) and diffraction grating recording medium of the present invention, and how the diffraction grating recording medium looks in each illumination direction. It is explanatory drawing to do.

  FIG. 4A is an explanatory diagram showing an enlarged pixel pattern. As shown in the figure, a pixel pattern composed of diffraction gratings (P1) and diffraction gratings (P2) having different grating pitches d1 to d4 (corresponding to wavelengths λ1 to λ4 of diffracted light) having substantially concentric circles is illustrated. However, in the present invention, the number of types of the grid pitch d for the purpose of color mixing may be at least two, and is not limited to the four types shown in FIG. 4 (a). There is no particular need for regularity.

  The pixel patterns P1 and P2 are allocated to the same medium, and finally recorded on the diffraction grating recording medium as shown in FIG. 4B.

  Then, as shown in FIG. 4 (c), the appearance of the diffraction grating recording medium in each illumination direction in which the saturation change continuously changes corresponding to the angle change, and the motif is the primary color in (c1). The background is observed in a mixed color (white), the motif and the lattice periodic structure of the background are the same in (c2), and the entire surface is shined uniformly, and the motif is observed in the primary color and the background is mixed (white) in (c3). The

  The diffraction grating pattern and diffraction grating recording medium of the present invention obtained above are pixel patterns arranged corresponding to the pixels of an image expressed by arranging minute cells or dots made of a diffraction grating on the substrate surface. The structure includes at least two types of structures in which the grating angle and the grating interval of the diffraction grating are not a single structure, and changes the grating interval in association with the grating angle to rotate the substrate or the illumination direction. As a result, the hue and saturation of the display color of the image are changed, and a more diverse and highly original pattern can be produced, so that the visual image is novel and the forgery prevention can be further enhanced.

It is explanatory drawing explaining an example of the embodiment about the diffraction grating pattern and diffraction grating recording medium of this invention. It is explanatory drawing explaining an example of the embodiment about the diffraction grating pattern and diffraction grating recording medium of this invention. It is explanatory drawing explaining an example of the embodiment about the diffraction grating pattern and diffraction grating recording medium of this invention. It is explanatory drawing explaining an example of the embodiment about the diffraction grating pattern and diffraction grating recording medium of this invention. It is explanatory drawing explaining an example of the pattern used as a motif of the diffraction grating recording medium in a general image, and image information. It is explanatory drawing explaining an example of the embodiment about the conventional diffraction grating pattern and a diffraction grating recording medium. It is explanatory drawing explaining an example of the embodiment about the conventional diffraction grating pattern and a diffraction grating recording medium. It is explanatory drawing explaining an example of the embodiment about the conventional diffraction grating pattern and a diffraction grating recording medium. It is explanatory drawing explaining an example of the embodiment about the conventional diffraction grating pattern and a diffraction grating recording medium. It is explanatory drawing explaining the state which observes diffracted light when white light injects into a diffraction grating recording medium with a specific angle. It is explanatory drawing explaining an example of the embodiment about the conventional diffraction grating pattern and a diffraction grating recording medium.

Claims (5)

  The pixel pattern structure that is arranged corresponding to the pixel of the image expressed by arranging minute cells or dots made of a diffraction grating on the substrate surface is a structure in which the grating angle and the grating interval of the diffraction grating are single. And at least two or more structures, and the hue or saturation of the display color of the image is changed by changing the lattice interval in conjunction with the lattice angle and rotating the substrate or the illumination direction. And a diffraction grating pattern.   The diffraction grating pattern according to claim 1, wherein a hue or saturation of a display color of the image is reversed as the substrate or the illumination direction is rotated.   The diffraction grating pattern according to claim 1, wherein the hue or saturation of the display color of the image continuously changes as the substrate or the illumination direction rotates.   The pixel pattern structure is composed of two types of pixel patterns in which the diffraction grating at the rotation base point and the end point are interchanged, and a diffraction grating common to both pixels is arranged in a rotation region of a predetermined angle, and the hue of the display color of the image The diffraction grating pattern according to claim 1, wherein the image is inverted and the image forms a latent image at a predetermined angle of the rotation region.   A diffraction grating recording medium comprising the diffraction grating pattern according to any one of claims 1 to 4.