JP2011007967A - Multiplex diffraction grating recording medium and mechanical reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiplex diffraction grating recording medium in which motifs are excellently observed in any region, visible wavelength region and infrared wavelength region or ultraviolet wavelength region, and to provide a mechanical reading device.SOLUTION: Pixels composing a motif using a first pixel pattern is composed by a diffraction grating which diffracts visible light, pixels composing a motif using a second pixel pattern is composed by a diffraction grating which diffracts infrared light or ultraviolet light, and a multiplex pixel pattern is composed at the position of pixels at which these motifs are superimposed. The multiplex pixel pattern is related to a multiplex diffraction grating medium with which different motifs are observed in different wavelength regions by defining micro pixels by further dividing a pixel composing one closed region and defining a unit micro pixel arrangement in which the micro pixels are arranged in m-lines×n-columns, and related to the mechanical reading device using the multiplex diffraction grating medium.

Description

  The present invention relates to a multiple diffraction grating recording medium and a machine reader. In particular, the present invention relates to a diffraction grating recording medium considering forgery prevention and machine reading.

  Conventionally, as a method for preventing forgery of securities, cards, etc., it has been common to attach a hologram to the surface of an object and discriminate it by visual identification. In addition, in order to resolve the ambiguity of visual identification, the authenticity is determined by reproducing and checking the hologram with the reproduction light irradiated from a specific angle using the hologram having a specific diffraction characteristic. Is known as the prior art.

  In this way, diffraction gratings and holograms are subject to visible diffracted light and undergo color changes and image changes, and are mostly aimed at preventing counterfeiting visually. It is no longer difficult to read, forge and forge easily with light.

  In addition, diffraction gratings and holograms intended for machine reading are generally those that receive visible diffracted light and perform mechanical reading, and diffraction gratings having a lattice constant comparable to the wavelength of visible light are optical. By utilizing the anisotropy and combining diffraction gratings with different grating directions, or a diffraction grating having a grating constant less than or equal to the wavelength of visible light, the coherent characteristics are poor. An authenticity confirmation medium and an authenticity confirmation method that enable confirmation of authenticity by giving a characteristic to the diffraction characteristic or reflection characteristic of the diffraction grating instead of generating an image by light irradiation. For example, see Patent Document 1).

  By changing the line width, pitch, and arrangement angle of the grating lines constituting the diffraction grating, it is possible to create diffraction gratings having different optical characteristics. A plurality of pixels having different optical characteristics, for example, the same line width and pitch of lattice lines and different arrangement angles are prepared, and for the first motif, the first arrangement angle is 45 degrees. If pixels are arranged side by side and the second pixel with an arrangement angle of 90 degrees is arranged side by side, the two motifs can be recorded on the same plane, and the optical characteristics are different. Therefore, these two motifs have different observation angles and can be distinguished and observed as separate motifs. In addition, when expressing a plurality of motifs in which these pixels overlap, the concept of sub-pixels in which one pixel is divided into four parts is introduced, and a predetermined motif is expressed by a pixel array of M rows and N columns In addition, the pixel array of M rows and N columns is an array of (2 × M) rows (2 × N) columns that is an array of sub-pixels, and when both motifs are displayed on an equal basis, the motif A is in the upper left and lower right The motif B is assigned to the lower left and upper right diagonal subpixels, and the motif A subpixel has a diffraction grating pattern with a grid line forming angle of 45 °, and the motif B subpixel. Since a diffraction grating pattern having a grating line forming angle of 90 ° is formed on the pixel, the observable angles of the motifs A and B are different, and are observed separately as separate motifs. Creation device (for example, For example, see Patent Document 2).

JP 2004-77954 A Japanese Patent No. 3383004

  However, since the holograms of the prior art are generally discriminating by authenticity by visual appearance by always causing an image to appear, the anti-counterfeiting effect is where the visible light is irradiated to the diffraction grating or hologram. It is relatively easy to see if there is a part. For this reason, it is easy to manufacture counterfeit products that are indistinguishable from genuine ones, and the effect of preventing forgery of holograms is low, and thus there is a problem that further development of anti-counterfeiting technology is necessary.

  Patent Document 1 is a case of a diffraction grating for machine reading that is read with visible light, and when irradiated with visible light, it is immediately perceived in which part of the hologram the element of machine reading is included. There was a problem that it was difficult to conceal information for the purpose of reading.

  In Patent Document 2, the first motif and the second motif have a plurality of optical characteristics by changing at least one of the line width, pitch, and arrangement angle (arrangement angle) of the grating lines constituting the diffraction grating. Since the motif is recorded, the result is that a clear and reproducible hologram image is obtained, so this hologram records light of the same wavelength, that is, a hologram that is observed under both visible light. For example, each was not observed under different light such as under visible light and under infrared light.

  When a hologram that can be optically read is visually perceived, it cannot be observed with the naked eye unless it is reproduced with light in the visible wavelength region, and with a light in the infrared wavelength region or ultraviolet wavelength region. Even if light produced in the visible wavelength region is irradiated with light in the visible wavelength region, it will not be reproduced and will be observed in the dark, so that any of the visible wavelength region and the infrared wavelength region or the ultraviolet wavelength region will be reproduced. There were no holograms that were observed well in the region.

  Therefore, the present invention is composed of a motif composed of a diffraction grating having the same grating interval as the wavelength of visible light on the same medium, and a diffraction grating having a grating interval of the same order as the wavelength of infrared light or ultraviolet light. It is an object of the present invention to provide a multiple diffraction grating recording medium and a mechanical reading device that can be satisfactorily observed in any of the visible light region, the infrared light region, and the ultraviolet light region. .

  In order to solve the above-described problems, the present invention provides a multiple diffraction grating recording medium in which at least two motifs are recorded in duplicate by using a different pixel pattern for each motif by a diffraction grating on the same medium. The multiple diffraction grating recording medium comprises a plurality of first pixel patterns constituting a first motif which is one of at least two and a second motif which is the other of at least two A plurality of second pixel patterns and a multiple pixel pattern in which two pixel patterns arranged in the first motif and the second motif are arranged in the same closed region. The first pixel pattern is composed of a plurality of pixels that are visible light diffraction grating regions, arranged in a predetermined closed region at a predetermined grating interval and a predetermined angle of the grating lines of the diffraction grating. The second pixel pattern is composed of a plurality of pixels that are diffraction grating regions of infrared light or ultraviolet light, and the first pixel pattern and the second pixel pattern are assigned to the multiple pixel pattern. Is a multiple diffraction grating recording medium.

  In the present invention, the lattice spacing of lattice lines of pixels formed in one closed region constituting the first pixel pattern is 500 lines / mm to 1000 lines / mm that diffracts visible light. The lattice spacing of the lattice lines of pixels formed in one closed region constituting the pixel pattern is 300 lines / mm to 500 lines / mm that diffracts infrared light, or 1000 lines / mm that diffracts ultraviolet light. This is a multiple diffraction grating recording medium having 1500 lines / mm.

  The multiple pixel pattern of the present invention includes a first pixel pattern and a second motif constituting a first motif in a unit minute pixel array composed of minute pixels obtained by dividing one pixel into m rows and n columns. The second pixel pattern that constitutes a multi-diffraction grating recording medium having a rectangular shape, a dot shape, or a figure shape as a form of a minute pixel.

  The size of the minute pixel of the present invention is a multiple diffraction grating recording medium having a size of 100 μm or less.

  The multiple diffraction grating recording medium of the present invention is a multiple diffraction grating recording medium that is a hologram.

  Further, the above-mentioned mechanical reading device for a multiple diffraction grating recording medium, an installation table on which the multiple diffraction grating recording medium is placed, an irradiation unit that irradiates the multiple diffraction grating with visible light, infrared light, or ultraviolet light, Multiple diffraction grating recording comprising an imaging unit that irradiates irradiation light from an irradiation unit to capture an image of a multiple diffraction grating, a display unit that displays the captured image, and a recognition unit that recognizes the displayed image as a motif A machine reader for media.

  Further, the machine reading device for a multiple diffraction grating recording medium according to the present invention determines whether the motif recognized by the recognition unit is compared with a pre-recorded reference motif or outputs an arbitrary specific code to determine authenticity. And a mechanical reading device for a multiple diffraction grating recording medium.

  The multiple diffraction grating recording medium mechanical reader of the present invention is provided with a plurality of irradiation units for irradiating visible light, infrared light, or ultraviolet light.

  The mechanical reading device for a multiple diffraction grating recording medium according to the present invention uses the entire or a part of the motif obtained by irradiating the multiple diffraction grating recording medium with infrared light or ultraviolet light from the irradiating portion as diffraction light intensity. This is a machine reading device for a multiple diffraction grating recording medium that receives light and sequentially confirms the authenticity by receiving light intensity at a light receiving unit.

  According to the multiple diffraction grating recording medium and the mechanical reading device according to the present invention, the motif composed of the diffraction grating having the same grating spacing as the wavelength of visible light by the multiple diffraction grating, and the grating spacing is infrared light or ultraviolet light. A multiple diffraction grating recording medium in which a motif composed of diffraction gratings having the same wavelength as that of the recording medium is recorded, and an irradiation unit for irradiating visible light, infrared light, or ultraviolet light to a mechanical reader. Thus, when observing a multiple diffraction grating recording medium, it has become possible to satisfactorily observe any of the visible light region, the infrared light region, and the ultraviolet light region.

The figure which shows an example of the multiple diffraction grating recording medium of this invention. The figure which shows an example of the pixel pattern used for the multiple diffraction grating recording medium based on this invention. The figure which shows an example of the pattern expressing the multiple pixel pattern P3. The figure which shows the grating | lattice direction and grating | lattice space | interval of a diffraction grating in each pixel pattern which comprises each motif. The figure showing the difference in the image by the difference in an irradiation direction. 1 is a schematic diagram of a mechanical reading device for a multiple diffraction grating recording medium of the present invention. Schematic which shows the process of recognition in the recognition part E. FIG. The figure which shows an example of pattern recognition. The figure which shows another example of pattern recognition.

  First, a brief explanation of the principle matters regarding the multiple diffraction grating recording medium according to the present invention will be described, and the meanings of some terms will be defined.

  The basic principle of the present invention is to multiplex-record a plurality of motifs using a multiple diffraction grating in which at least two types of grating lines having different predetermined grating intervals d are recorded in the same closed region. This is recorded by setting the grating interval d to a value that diffracts visible light, infrared light, or ultraviolet light. The diffraction grating recording medium is an image formed by a set of a plurality of pixels expressed as a diffraction grating on the same medium.

  In the present invention, based on the basic principle, a pixel pattern is “a grid line having a predetermined grid interval d arranged in a predetermined closed region”. In the present invention, however, the pixel pattern is actually in the closed region. Is recorded at a predetermined angle φ, in the embodiment of the present invention, the pixel pattern is also used when “a grid line having a predetermined grid interval is arranged in a predetermined closed region at a predetermined angle”. May be written. A closed region is a region constituting one pixel.

A diffraction grating recording medium is manufactured by assigning a pixel pattern in which a diffraction grating is formed to each pixel constituting an image. In other words, the pixel pattern that becomes the motif A is obtained by arranging the pixel pattern at the pixel position where the motif A is arranged, and is recorded on the diffraction grating recording medium.
A multiple diffraction grating recording medium recorded with a plurality of overlapping motifs on the same medium will be described. As an example, in the case where two motifs of a first motif and a second motif are recorded on the same medium, the first pixel pattern is used for the pixels forming the first motif, and the second motif is used. A second pixel pattern is arranged for the pixels forming the motif. The first pixel pattern and the second pixel pattern have different predetermined grid intervals. If the pixels of the two motifs do not have a pixel region that overlaps, the pixels of both motifs are mixedly arranged. However, a plurality of motifs with overlapping pixels may have pixel regions that overlap each other, that is, pixel regions that are shared by two motifs.

The multiple diffraction grating recording medium according to the present invention has a structure having a pixel region shared by the two motifs of the first motif and the second motif.
The principle of the multiple diffraction grating recording medium of the present invention is that, on the same medium, the first pixel pattern whose predetermined grating distance d is about the same as the wavelength of visible light and the predetermined grating distance d 'are infrared light or ultraviolet light. A second pixel pattern having the same degree as the wavelength is recorded in multiple, only the first pixel pattern is observed in a visible light environment, and only the second pixel pattern is observed in an infrared light or ultraviolet light environment. The configuration is observed.
Therefore, the motif multiple diffraction grating recording medium records the first pixel pattern as the first motif at the predetermined angle φ and the second pixel pattern as the second motif at the predetermined angle φ ′ on the same medium. Then, in the pixel region shared by the first motif and the second motif, the first motif and the second motif are overlapped and recorded.

  Here, when the first motif and the second motif are multiplexed and recorded on the same medium, the first pixel pattern constituted by a plurality of pixels constituting the first motif and the second motif are constituted. A pixel portion that is an area shared by a second pixel pattern composed of a plurality of pixels is generated. This shared pixel portion is referred to as a “multiple pixel pattern” in the present invention, and pixels in both the first motif and the second motif are mixed in the closed region. Since it has the properties of both patterns, it is observed from any angle in the observation direction.

  Therefore, it is necessary to solve the problem of how to incorporate the pixel pattern of the first motif and the second motif into the multiple pixel pattern portion. Therefore, in the present invention, as a method for incorporating the pattern of the multiple pixel pattern portion, the “pixel” constituting one closed region is further divided arbitrarily to make the pixel smaller. One pixel divided into two is defined as a “small pixel”.

  When the motif A using the first pixel pattern shown in FIG. 1 (a) and the motif B using the second pixel pattern shown in FIG. 1 (b) are arranged and recorded, FIG. 1 (c) A multiple diffraction grating recording medium as shown in FIG. The multiple diffraction grating recording medium includes a first pixel pattern (P1) constituting the motif A, a second pixel pattern (P2) constituting the motif B, a first pixel pattern (P1), and a second pixel pattern ( P2) is composed of multiple pixel patterns (P3) that share pixels.

Therefore, one pixel of the multiple pixel pattern (P3) is further divided into arbitrary m rows and n columns as shown in FIG. 1D, and the minute pixels arranged in the divided m rows and n columns. Is defined as a “unit micropixel array”.
For some images to be recorded on the medium, an arrangement is created by arranging them in a predetermined pixel area corresponding to the pixel arrangement of these images. Since there are two patterns, the first pixel pattern (P1) and the second pixel pattern (P2), which are assigned to the unit minute pixel array, there are at least two minute pixels obtained by dividing the pixels into one row and two columns. It will be established.

In this example, the “unit micropixel array” has a size corresponding to one pixel, and one “unit micropixel array” is composed of 36 micropixels in 6 rows and 6 columns. Not limited to this.
Next, it is determined how the pixel pattern of which motif is arranged at each minute pixel position in the “unit minute pixel array”. For example, assuming that the pixel pattern of motif A and the pixel pattern of motif B are arranged in a checkered pattern in the multiple pixel pattern (P3) portion, recording is performed by overlapping motif A and motif B. 1 (c) showing the multiple diffraction grating recording medium to be formed constitutes the first pixel pattern (P1) constituting the motif A, the second pixel pattern (P2) constituting the motif B, and the motif A A first pixel pattern and a second pixel pattern constituting the motif B are constituted by a multiple pixel pattern (P3) arranged in a checkered pattern, and a pattern recorded as an actual multiple diffraction grating recording medium; Become.

  From the above, theoretically, any number of multiple motifs can be recorded in duplicate. However, as described above, since it is necessary to form a pixel in each diffraction grating region of visible light, infrared light, and ultraviolet light, it is practically difficult to record three or more motifs in an overlapping manner. is there.

  Embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the modes for carrying out the invention described below, and includes various other embodiments within the scope of the technology described in the claims.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing motifs and pixel patterns constituting the multiple diffraction grating recording medium of the present invention. FIG. 2 is a diagram showing an example of a pixel pattern used in the multiple diffraction grating recording medium according to the present invention. FIG. 3 is a diagram illustrating a pattern example expressing the multiple pixel pattern P3. FIG. 4 is a diagram showing the grating direction and the grating interval of the diffraction grating in each pixel pattern constituting each motif. FIG. 5 is a diagram illustrating differences in images due to differences in irradiation direction. FIG. 6 is a schematic diagram of a mechanical reading device for a multiple diffraction grating recording medium according to the present invention. FIG. 7 is a schematic diagram showing a recognition process in the recognition unit. FIG. 8 shows an example of a two-dimensional code as an example of pattern recognition. FIG. 9 shows an example of a code based on the presence or absence of a specific shape as another example of pattern recognition.

  The multiple diffraction grating recording medium according to the present invention expresses a motif composed of a set of a plurality of pixels as a multiple diffraction grating on the medium. In the present invention, a pattern (English letter “A”) expressed by arranging pixels as shown in FIG. 1A is called a motif.

  The pixels are arranged in a predetermined closed region at a predetermined lattice interval (d) and a predetermined angle (φ). As a pixel pattern, for example, the configuration shown in FIGS. 2A and 2B is used. Become. The method for producing a multiple diffraction grating recording medium according to the present invention is usually carried out using a computer.

  Each process described below is executed by using a computer, and motif image information prepared as image data corresponding to a motif is a general image data called raster image data. The motif image information may be prepared by using a scanner or a design drawn on paper by a scanner, and detailed description thereof is omitted.

  The present invention utilizes the fact that a plurality of diffraction gratings having different diffraction characteristics can be recorded in one thin medium as one characteristic of a multiple diffraction grating. The first pixel pattern, which is a plurality of minute diffraction gratings reproduced with visible light when irradiated with infrared light, and the plurality of minute images reproduced with infrared light or ultraviolet light when irradiated with infrared light or ultraviolet light Two types of pixel patterns called a second pixel pattern, which is a diffraction grating, are incorporated and recorded. When irradiated with visible light, the first pixel pattern can be observed. Since the second pixel pattern that is observed when light is irradiated is not observed, it is difficult to recognize that the second pixel pattern region exists in the same region, and it is difficult to produce a duplicate.

  In general, when a predetermined pattern or the like is expressed using a diffraction grating, the pattern or the like is constituted by a set of a plurality of regions, and a predetermined diffraction grating pattern is arranged in each region. At this time, the diffraction grating pattern to be arranged is varied for each region. In other words, it is well known that visually changing symbols and the like can be observed by changing the pitch and arrangement angle of the grid lines.

  In the multiple diffraction grating recording medium according to the present invention, the first pixel pattern in which the predetermined grating interval d is approximately the same as the wavelength of visible light in a set of a plurality of regions expressing a pattern or the like as described above is set to a predetermined angle φ. A predetermined pattern in which a motif A configured with a predetermined angle φ ′ and a second pixel pattern having a predetermined lattice interval d ′ approximately equal to the wavelength of infrared light or ultraviolet light is recorded. In the pixel area where the motif multiple diffraction grating recording medium is formed and the motif A and the motif B are shared, the first pixel pattern of the motif A and the second pixel pattern of the motif B are recorded overlappingly. Become.

  One pixel of the multiple pixel pattern portion in which the first pixel pattern and the second pixel pattern overlap is further divided into small pixels of arbitrary m rows and n columns, and these divided m rows and n columns are divided. A minute pixel array is configured by arranging minute pixels, and either the first pixel pattern of motif A or the second pixel pattern of motif B is assigned to each minute pixel. This allocation is realized, for example, by arranging the first pixel pattern and the second pixel pattern in a checkered pattern or the like. Therefore, since the multiple pixel pattern part is embedded in a minute area, it is recognized as the first pixel pattern composed of pixels that are diffracted when irradiated with visible light when viewed with the naked eye. Thus, it is difficult to recognize which part is the second pixel pattern.

  The multiple diffraction grating recording medium according to the present invention configured as described above may be referred to as a latent image diffraction grating in the present invention. In addition, when irradiated with infrared light or ultraviolet light, the image of motif A in which a plurality of first pixel patterns, which are diffraction grating images of visible light that have been visible until now, disappears, and a latent image appears in the same region. In the present invention, a phenomenon in which an image of a motif B in which a plurality of second pixel patterns configured as shown above appears is referred to as an image switch / diffraction grating.

  The diffraction grating is formed by forming a large number of grooves having a three-dimensional uneven structure on the surface of the medium. In the present invention, not only the original diffraction grating but also a reference wave and an object wave are formed. What includes a hologram in which optical interference fringes are recorded on a medium is collectively referred to as a diffraction grating.

  The multiple diffraction grating recording medium according to the present invention has an image of motif A in which a plurality of first pixel patterns, which are diffraction grating images of visible light that have been visible until now when irradiated with infrared light or ultraviolet light. It is possible to read with the machine reading device that the image of the motif B that disappears and a plurality of second pixel patterns configured as latent images appear in the same region appears. That is, by changing the predetermined lattice interval (d) to the wavelength of visible light, infrared light, or ultraviolet light, it is possible to distinguish and read by an optical mechanical reader. Therefore, the machine reading device causes the first pixel pattern or the second pixel pattern to appear by changing the light source, and thus creates a multiple diffraction grating recording medium in which the machine reading element is not perceived. be able to.

  In this way, if the pixels forming the multiple pixel pattern portion are divided into minute pixels, and the first pixel pattern and the second pixel pattern are recorded in accordance with the allocation, recording with the naked eye is possible. Although it is difficult to recognize the second pixel pattern, there is no problem in performing reading under a predetermined optical condition. For a third party, since it is difficult to recognize the presence of the second pixel pattern, forgery is very difficult.

In the multiple diffraction grating recording medium of the present invention, the first pixel pattern has a plurality of minute patterns having the same lattice constant as the wavelength of visible light and having the same grating direction or different grating directions. It is manufactured by arranging a diffraction grating. The second pixel pattern has a lattice constant comparable to the wavelength of infrared light or ultraviolet light, and can have the same configuration and arrangement as the first pixel pattern.
In addition, the multiple pixel pattern portion in which the first pixel pattern and the second pixel pattern share a pixel is divided into minute pixels, and the first pixel pattern and the second pixel pattern assigned to each minute pixel are minute. The diffraction gratings are arranged in close contact with each other.

  In order to manufacture the multiple diffraction grating recording medium of the present embodiment in which the micro diffraction gratings of the first pixel pattern and the second pixel pattern are arranged in the multiple pixel pattern portion, a conventional diffraction grating is manufactured. It is produced by a laser or electron beam drawing apparatus similar to the method.

In general, the relationship between the frequency λ of light for observing the diffraction grating and the angle θ for observing the light source is
It is determined by λ = 1 / dsinθ. At this time, d is the number of gratings constituting the diffraction grating.
Also in the present invention, the diffraction grating is manufactured while maintaining this relationship.
Further, by changing the grating direction of the diffraction grating of the second pixel pattern, it is possible to observe a moving image when observed with infrared light.

  Although the size of the minute pixel in the above is arbitrary, it is set to 100 μm or less, which is a size that exceeds the range of the resolving power of the human eye at a normal distance when a person observes and does not know the presence of the minute pixel. By doing so, it becomes difficult to analyze a diffraction grating in which a person who acts improperly has a latent image.

  The multiple diffraction grating recording medium according to the embodiment of the present invention will be described below. FIG. 1 is a diagram showing an example of a multiple diffraction grating recording medium according to the present invention. The structure of the produced multiple diffraction grating recording medium is the same as that of the conventional one. However, as a feature of the multiple diffraction grating recording medium of the present invention, when a plurality of motifs are recorded on the same medium, a plurality of motifs are recorded. There are various forms of representation of the pixels forming the multiple pixel pattern portion in which the pixel patterns of the motif share the pixels. As an example, divide a pixel into small areas that are indistinguishable visually, and irradiate infrared light or ultraviolet light with a first pixel pattern composed of pixels that diffract by irradiating visible light Are incorporated in a checkered pattern so as to be present in the same region on the diffraction grating recording medium, and the regions are overlapped. In this embodiment, the checkers are arranged in a checkered pattern, but the present invention is not limited to this, and any other pattern may be used. In the case of the present embodiment, it is preferable that the pixels of the motif A and the pixels of the motif B are arranged at alternate positions on the assumption that both the motifs are displayed on an equal basis.

FIG. 1A is a diagram showing a motif “A” using the first pixel pattern (P1). The pixels constituting “A” are constituted by a diffraction grating that diffracts with visible light. At this time, each pixel constituting “A” may have a different pixel pattern.
FIG. 1B is a diagram showing the motif “B” using the second pixel pattern (P2). The pixels constituting “B” are constituted by diffraction gratings that diffract with infrared light or ultraviolet light. At this time, each pixel constituting “B” may have a different pixel pattern.
FIG. 1 (c) is a diagram showing a multiple diffraction grating recording medium recorded by arranging two motifs A and B as shown in FIGS. 1 (a) and 1 (b). The pixel patterns P1 and P2 used for each of the motifs, and the motif “A” and the motif “B” are composed of multiple pixel patterns (P3) at positions where pixels are shared.

  FIG.1 (d) is an enlarged view when one closed area | region of the multiple pixel pattern (P3) of FIG.1 (c) is observed. This is an example of a unit micropixel array in which pixels constituting one closed region are further divided into arbitrary m rows and n columns and micropixels are arranged. One pixel constituting each motif and the unit minute pixel array have the same size. In the present embodiment, this unit minute pixel arrangement is described as a 6-row 6-column arrangement, so that it is divided into pixels constituting one closed region and 36 minute pixels in 6 columns and 6 rows. That is, the unit micropixel array has the same size.

The multiple pixel pattern (P3), in which the first pixel pattern (P1) expressing the motif A and the second pixel pattern (P2) expressing the motif B share pixels, is the first pixel pattern (P1) and the second pixel pattern (P2) are allocated and arranged in 36 minute pixels, and as an example, an array arranged in an alternating checkered pattern is shown. . The fineness of each side of the quadrangle that forms a checkered pattern that is one minute pixel that constitutes one of the arrays depends on the size of the pixel, but may be one-tenth the size of the pixel. However, it may be finer. For example, when the size of the pixel is 100 microns per side, the size of a checkered square that is one minute pixel is preferably about 10 microns.
Since the predetermined lattice interval (d) constituting the pixel pattern is about 1 micron, if the size of one side of a checkered square, which is one minute pixel, is larger than 1 micron, it is arranged in a checkered pattern. A pixel pattern is established.

FIG. 2 is a diagram showing an example of a pixel pattern used in the multiple diffraction grating recording medium according to the present invention. Although the grating interval d of the pixel pattern differs depending on the light source irradiated to the multiple diffraction grating recording medium and the angle at the time of observation, for example, the observation angle is observed in the range of 15 degrees to 75 degrees from the relationship of d = sin θ / λ. Assuming that, in the case of visible light, approximately 500 lines / mm to 1500 lines / mm, in the case of infrared light, approximately 250 lines / mm to 1000 lines / mm, in the case of ultraviolet light, approximately 800 lines / mm. ˜3000 / mm.
FIG. 2A is a diagram that defines a first pixel pattern that constitutes a pixel that is a visible light diffraction grating region. The pixels formed in one region are very minute pixels formed in a predetermined closed region at a predetermined angle φ with lattice lines having a predetermined lattice interval d, and 10 rows 7 shown in FIG. It has a size corresponding to each pixel in the array of columns. The grating interval d takes a value that diffracts visible light as described above, and is preferably a value of 500 lines / mm to 1000 lines / mm.
FIG. 2B is a diagram that defines a second pixel pattern that constitutes a pixel that is a diffraction grating region of infrared light. The pixels formed in one region are very minute pixels formed in a predetermined closed region with a grid line having a grid interval d ′ at a predetermined angle φ ′, and the 10 rows shown in FIG. The size corresponds to each pixel in the 7-row array. The grating interval d ′ takes a value that diffracts infrared light as described above, and is preferably a value of 300 lines / mm to 500 lines / mm.

  Thus, the pixels formed in one closed region are determined by two parameters of a predetermined grid interval and a predetermined angle, and by changing at least one of them, a different pattern can be obtained. Since the diffraction grating is composed of a micro area of μ units, the existence of the second pixel pattern area cannot be perceived when the first pixel pattern area is observed.

  When ultraviolet light is selected for the second pixel pattern, the lattice spacing takes a value that diffracts ultraviolet light as described above, but is preferably a value of 1000 lines / mm to 1500 lines / mm.

  In this embodiment, an example of a multiple diffraction grating recording medium in which two motifs of a visible light diffraction grating area and an infrared light diffraction grating area are recorded on the same medium has been described. Instead, ultraviolet light may be used, and a configuration in which three motifs in the diffraction grating regions of visible light, infrared light, and ultraviolet light are recorded in an overlapping manner is also possible.

FIG. 3 is a diagram illustrating an example of a checkered pattern representing a multiple pixel pattern (P3) among the pixel patterns constituting the latent image diffraction grating. 3A shows an example in which a rectangle, (b) is a rectangle, (c) is a dot, (d) is a figure (star shape), and (e) is a triangle pattern arranged. However, the present invention is not limited to this, and may be a diamond shape or any design figure or pattern.
In the present invention, if m and n in m rows and n columns in a unit micropixel array arranged in m rows and n columns are normally configured as m = n, motif A and motif B can be easily arranged at the same time. , It is not always necessary to set m = n.

FIG. 4 is a diagram showing the grating direction and the grating interval of the diffraction grating in each pixel pattern constituting each motif.
FIG. 4A is a diagram showing the difference in the grating direction of the diffraction grating in the pixel pattern, and the grating direction does not have to be uniquely determined and is set with an angle (φ). The angle (φ) may be different for each pixel pattern, and it is expressed so that the image of the motif is switched by gradually changing the value of the angle (φ) to 0 °, 5 °, 10 °, and 15 °. It is possible. This is true for both the first pixel pattern constituting the motif A observed with visible light and the second pixel pattern constituting the second motif B observed with infrared light or ultraviolet light.
FIG. 4B is a diagram showing a difference in color due to a change in the grating interval (d) of the diffraction grating in the pixel pattern. The grating interval (d) does not have to be uniquely determined, and is observed with visible light. As can be seen, it is only necessary to create a lattice pattern with a predesigned lattice interval (d), and by gradually changing the value of the lattice interval (d) to 500, 550, 600, 650, 700, It is possible to express the colors so as to be switched, for example, to yellow, light-brown, orange, vermilion, and red.

FIG. 5 is a diagram illustrating differences in images due to differences in irradiation direction.
FIG. 5A is a diagram showing a state in which the entire multiple diffraction grating recording medium is irradiated. In order to reduce the influence of the image of the motif A, it is preferable to set the grating directions of the diffraction grating in the pixel pattern in different directions for the motif A and the motif B. In this embodiment, as an example, the design is performed by changing the lattice direction of motif A and motif B by 90 °.
When observing the multiple diffraction grating recording medium with visible light, the irradiation direction of visible light is as shown in FIG. 5B when light is irradiated from the direction in which the first pixel pattern is designed from the upper direction in the figure. The observation image of motif A is observed.
When the multiple diffraction grating recording medium is observed with infrared light or ultraviolet light, the irradiation direction of infrared light or ultraviolet light is irradiated from the left side of the figure, and as shown in FIG. Is observed.

FIG. 6 is a schematic view of a machine reading device for reading the multiple diffraction grating recording medium of the present invention.
The basic components of the machine reading device are an installation table 2 on which the multiple diffraction grating recording medium 1 is installed, a visible light irradiation unit L1, an infrared light (or ultraviolet light) irradiation unit L2, and a CCD camera for observation. A class C, a display unit D that displays a captured image, a recognition unit E that performs pattern recognition, and a determination unit F that performs authenticity determination.

  In the multiple diffraction grating recording medium 1 manufactured in this example, the first pixel pattern has a lattice constant approximately equal to the wavelength of visible light, and the second pixel pattern has the same wavelength as that of infrared light. Because it is configured with a lattice constant of about, by setting two light sources of visible light and infrared light and changing the wavelength of visible light or infrared light, by an optical mechanical reader The configuration is such that it can be read distinctly. When the infrared light is irradiated, the image of the motif A in which a plurality of first pixel patterns, which are visible light diffraction grating images that have been seen so far, disappears and is formed as a latent image in the same region. An image switch / diffraction grating, which is a phenomenon in which an image of a motif B in which a plurality of second pixel patterns are arranged, can be read by a machine reader. In this embodiment, the second pixel pattern is a diffraction grating image of infrared light. However, in the case where ultraviolet light is used instead of infrared light, the irradiation unit L2 is ultraviolet light. In addition, a multiple diffraction grating recording medium expressing three motifs may be produced by recording a motif composed of pixel patterns having a lattice constant equivalent to each wavelength of ultraviolet light on the same medium. Machine reading is possible.

As shown in FIG. 6, when the multiple diffraction grating recording medium 1 is placed on the installation base 2 on which the sample of the machine reader is placed and irradiated with visible light L1 at an angle θ1 from the normal direction, a plurality of first pixel patterns are formed. An image of the arranged motif A is observed by the CCD camera group C. At this time, there may be a plurality of L1s. Similarly, infrared light or ultraviolet light L2 is irradiated with θ2 from the normal direction, and the obtained image is observed by the CCD camera group C. At this time, there may be a plurality of L2. Moreover, when observing by irradiating visible light L1 for the purpose of observation, it may be confirmed with the naked eye without using the CCD camera C.
An image of the motif A observed by irradiation with visible light and a motif B observed by irradiation with infrared light are captured by the CCD camera C and displayed on the display unit D. A computer or the like is used as the display unit D.
The image pattern displayed on the display unit D is recognized by the recognition unit E, and then the authenticity of the recognized image pattern is compared with each image pattern stored in advance in the determination unit F.

In recognition by the recognition unit E, pattern recognition is generally performed in which the shape of the input motif to be recognized is checked for the degree of coincidence with the shape of the reference motif registered in the memory of the recognition unit in advance. (FIG. 7). In order to see the degree of coincidence, the input motif and the reference motif are compared. For comparison, a commonly used projection method may be used. Alternatively, pattern recognition may be performed by creating a motif in the form of a code that takes into account machine reading such as a two-dimensional code (FIG. 8). Alternatively, a method of creating a motif in a predetermined shape and recognizing whether or not a specific shape exists at the position of the shape may be used (FIG. 9). These are equivalent to pattern recognition that is generally performed.
Generally, the determination unit F determines whether or not the threshold value is exceeded by providing a threshold value and having the comparison result of the recognition unit E. A general determination method may be used to determine whether the recognition result is good or bad.

  As described above in detail, the multiple diffraction grating recording medium of the present invention includes a first pixel pattern, which is a plurality of diffraction gratings reproduced by visible light when irradiated with visible light in one medium. When irradiated with infrared light or ultraviolet light, the second pixel pattern, which is a plurality of diffraction gratings reproduced by infrared light or ultraviolet light, is recorded in an overlapping manner, and the first pixel pattern and the second pixel are recorded. The multiple pixel pattern portion where the pattern overlaps is divided into minute pixels, and the minute pixels of the first pixel pattern and the second pixel pattern assigned to each minute pixel are arranged closely in contact with each other. In the multiple diffraction grating recording medium of the present invention, only the first pixel pattern is observed when irradiated with visible light, and only the second pixel pattern is observed when irradiated with infrared light or ultraviolet light. It can be an image switch / diffraction grating that switches the image by irradiation light, making it difficult to recognize that there are two pixel patterns in the same region and making it difficult to make a duplicate. be able to.

1 Multiple diffraction grating recording medium
2 Installation stand C CCD
D Display unit E Recognition unit F Determination unit L1 Visible light irradiation unit L2 Infrared light or ultraviolet light irradiation unit

Claims (8)

In a multiple diffraction grating recording medium in which at least two motifs are recorded overlappingly by a diffraction grating of at least two types of pixel patterns on the same medium,
The multiple diffraction grating recording medium includes a plurality of first pixel patterns formed by a first grating interval constituting a first motif that is one of at least two motifs;
A plurality of second pixel patterns formed by a second lattice interval constituting a second motif which is the other of at least two motifs;
The two pixel patterns in which the first motif and the second motif are arranged are divided by the first pixel pattern and the second pixel pattern as a multiple pixel region shared within the same closed region. Consisting of a third pixel pattern,
The first pixel pattern, the second pixel pattern, and the third pixel pattern are arranged in a predetermined closed region at a predetermined grating interval of grating lines of the diffraction grating,
The first pixel pattern is composed of a plurality of pixels which are visible light diffraction grating regions,
The second pixel pattern is composed of a plurality of pixels that are diffraction grating regions of infrared light or ultraviolet light,
In the third pixel pattern, one pixel is configured by arranging the first pixel pattern and the second pixel pattern alternately and regularly.
The grating interval of the first pixel pattern is 500 / mm to 1000 / mm that diffracts visible light, and the grating interval of the second pixel pattern is 300 / mm to diffract infrared light. A multiple diffraction grating recording medium having 500 lines / mm or 1000 lines / mm to 1500 lines / mm for diffracting ultraviolet light. The multiple pixel pattern comprises a first pixel pattern constituting the first motif and a second motif in a unit minute pixel array composed of minute pixels obtained by dividing one pixel into m rows and n columns. 2. The multiple diffraction grating recording medium according to claim 1, wherein the second pixel patterns are alternately arranged, and the minute pixels have a rectangular shape, a dot shape, or a figure shape. The multiple diffraction grating recording medium according to claim 2, wherein a size of the minute pixel is 100 μm or less. 4. The multiple diffraction grating recording medium according to claim 1, wherein the multiple diffraction grating recording medium is a hologram. A machine reading device for a multiple diffraction grating recording medium according to any one of claims 1 to 4,
An installation table on which the multiple diffraction grating recording medium is placed;
An irradiation unit for irradiating the multiple diffraction grating with visible light, infrared light, or ultraviolet light;
An imaging unit that irradiates irradiation light from the irradiation unit to capture an image of the multiple diffraction grating;
A display unit for displaying the captured image;
A machine reading device for a multiple diffraction grating recording medium, comprising: a recognition unit that recognizes the displayed image as a motif. The multiple diffraction grating recording according to claim 5, further comprising a determination unit that compares the motif recognized by the recognition unit with a reference motif recorded in advance or outputs an arbitrary specific code to determine authenticity. Media machine reader. The mechanical reading device for a multiple diffraction grating recording medium according to claim 5 or 6, wherein a plurality of irradiation units for irradiating visible light, infrared light, or ultraviolet light are provided. The whole or part of the motif obtained by irradiating the multiple diffraction grating recording medium with infrared light or ultraviolet light from the irradiation unit is received as diffraction light intensity, and the light intensity is sequentially received by the light receiving unit. The mechanical reading device for a multiple diffraction grating recording medium according to claim 5, wherein the authenticity is confirmed by the method of claim 5.

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