JP4403544B2 - Information recording medium having micro perforation pattern and method for producing the same - Google Patents

Description

  The present invention relates to an information recording medium having a micro perforation pattern and a manufacturing method thereof, and more particularly to an information recording medium in which an image binarized by Fourier transform is formed as a micro perforation pattern and a manufacturing method thereof.

  In order to improve the security of a paper ticket or the like, as disclosed in Patent Document 1, there is an example in which a perforated thread is formed on a thread that is engraved on a paper ticket. Recognizable perforations in this case are letters, numbers, images, marks, etc., and can be recognized visually. As a perforation method for providing such a perforation, as described in paragraph [0041] of Patent Document 1, there is a method of forming a perforation by condensing laser light onto a perforation target with a lens and generating heat.

On the other hand, Patent Document 2 introduces a technique for recognizing a reproduced image by performing Fourier transform on an image to form a binarized pattern on a film. As described in paragraph [0007] of Patent Document 2, the binarization of the Fourier transform image is performed by checking the phase of each pixel of the Fourier transform image and when the phase is from minus 90 ° to plus 90 °. It is performed by assigning a certain value Tp (for example, transparent), and otherwise assigning another certain value Tm (for example, black). The range for assigning Tp can be set to other than minus 90 ° and plus 90 °. Further, the range for assigning Tp can be determined not from the phase but from the amplitude. And in patent document 2, the example which has arrange | positioned several Fourier-transform images on the same film is shown by [FIG. 2], and when a film is observed on specific conditions, a reproduced image will change continuously. There is no problem with just one type of image.
JP 2003-286893 A Japanese Patent Laid-Open No. 10-282870

  The present invention has been made in view of such a situation in the prior art, and its purpose is to provide cards such as ID cards and credit cards, certificates, commuter passes, cash vouchers such as gift certificates, and printed matter. In addition to visible pattern information such as print information, a binarized pattern of Fourier transform images is formed on an information medium made of paper or plastic, thereby improving its security, adding data, and adding identification. That is.

  An information recording medium having a micro-perforation pattern according to the present invention that achieves the above object is obtained by dividing a phase image or an amplitude image of a Fourier transform image of an original image into pixels and binarizing it according to the phase value or amplitude value. The perforation that penetrates the medium is provided at the medium position of the pixel corresponding to one of the converted values, and the perforation is not provided at the medium position of the pixel corresponding to the other value. To do.

  In this case, the area in which the Fourier transform image is recorded by perforation may be arranged so as to entirely or partially overlap the area in which the visible pattern information is recorded.

  Further, it is desirable that each pixel has a vertical and horizontal dimension in the range of 5 to 50 μm and the perforation has a diameter in the range of 2.5 to 25 μm.

  The medium is typically paper or a plastic sheet.

  In the method for producing an information recording medium having a micro-perforated pattern according to the present invention, a phase image or an amplitude image of a Fourier transform image of an original image is divided into pixels and binarized according to the phase value or amplitude value, and binarized. In this method, a hole penetrating the medium is opened by laser light irradiation at the medium position of the pixel corresponding to the other value.

  In this case, the medium is a paper or plastic sheet, and the perforations are typically perforations in the range of 2.5-25 μm in diameter.

  In the method for recognizing an information recording medium having a micro-perforation pattern according to the present invention, a phase image or an amplitude image of a Fourier transform image of an original image is divided into pixels and binarized according to the phase value or amplitude value, and binarized. Information having a micro-perforation pattern that is recorded without a perforation provided at the medium position of the pixel corresponding to the other value, and without a perforation provided at the medium position of the pixel corresponding to the other value. In this method, a point light source is arranged behind the recording medium and observed from the surface side of the information recording medium.

  According to the information recording medium having a micro-perforated pattern of the present invention, a manufacturing method thereof, and a recognition method, an arbitrary hidden image can be recorded as a micro-perforated pattern on a paper medium or the like. (Unique) becomes possible. In addition, since the method for recognizing the information recording medium is simplified, the cost can be extremely reduced.

  Details of the information recording medium having the micro-perforated pattern of the present invention, a method for producing the same, and a method for recognizing the same will be described below.

  The present invention combines a perforation technique using laser light known in Patent Document 1 and the like and a binarization technique for a free image of an image proposed in Patent Document 2 to provide an information medium made of paper or plastic. It improves security.

  FIG. 1 shows an example of an information recording medium manufactured according to the present invention. FIG. 1A is a plan view in the case where the information recording medium 10 is in the form of a gift certificate or an admission ticket, and a laser perforation area 1 according to the present invention is provided in an appropriate area of the information recording medium 10. FIG. 1B is a perspective view when the information recording medium 10 is in the form of a postcard, and a laser perforation area 1 according to the present invention is provided in an appropriate area of the information recording medium 10. Here, the laser perforation region 1 may be provided not only in the blank portion of the information recording medium 10 but also in a manner that entirely or partially overlaps the region where the visible pattern information is recorded.

  Here, as described in paragraph [0007] of Patent Document 2, the laser perforation region 1 has a visually recognizable image to be recorded, for example, an arbitrary pattern (logo, company name), a machine recognizable bar, and the like. Image data such as a code (primary and two-dimensional) is created, and the Fourier transform image is obtained by Fourier transforming the image data, and the entire Fourier transform image has, for example, vertical and horizontal dimensions. The pixel is divided into pixels of 5 to 50 μm, the phase is checked for each pixel, and when the phase is from minus 90 ° to plus 90 °, a certain value Tp (for example, transparent) is assigned, and the value Tm in the pixels of other phases is assigned. (For example, black) is assigned. The range for assigning Tp can be set to other than minus 90 ° and plus 90 °. Further, the range for assigning Tp can be determined not from the phase but from the amplitude.

  In addition, as will be described later based on the present invention, a hole 2 having a diameter smaller than the size of the pixel, for example, 2.5 to 25 μm, is provided in paragraph [0041] of Patent Document 1 as described later. As described, the laser beam is condensed and perforated in the paper or the plastic sheet of the information recording medium 10, and no perforation is provided in the pixel to which Tm is assigned.

  FIG. 2 shows a state in which an image recorded as a Fourier transform image is reproduced and observed from an information recording medium 10 having a laser perforation area 1 in which such a laser perforation 2 is provided and a binarized Fourier transform image is recorded. 2A, when the point light source 11 is arranged behind the information recording medium 10 and the laser perforation region 1 on the surface of the information recording medium 10 is observed with the eye E, FIG. As shown in FIG. 5B, an image 3 recorded by performing point Fourier transform around the point light source 11 corresponding to the Fourier transform image, in this case, two “DNP” can be reproduced and viewed. In this case, the image 3 is reproduced as if the recognition image 3 exists around the point light source 11 by the light diffracted by each micro-perforation 2 corresponding to the dot of the perforated image in the laser perforation region 1.

  Of course, as described in Patent Document 2, a plurality of images are subjected to Fourier transform and then binarized, and the plurality of Fourier transform images are arranged to view the information recording medium 10 in the direction and information. A plurality of images may be reproduced according to the position of the recording medium 10 or the position of the point light source 11.

  FIG. 3A shows an image “D” as an example of a visually recognizable image to be recorded. An amplitude image of a Fourier transform image of this image is shown in FIG. As described above, the entire Fourier transform image is divided into pixels having vertical and horizontal dimensions of, for example, 5 to 50 μm, the amplitude is examined for each pixel, and the amplitude is normalized to 1, for example, 1 to 0. In the case of 5, for example, transparent is assigned, and when the amplitude is a standardized value, for example, 0.5 to 0, for example, opaque is assigned, and for the transparent assigned pixel, a hole 2 having a diameter smaller than the size of the pixel is lasered. As shown in FIG. 2 (b), the light is condensed and perforated in the medium, and no perforation is provided in the pixels to which the opacity is assigned. As shown in FIG. Two images 3 recorded by Fourier transform can be viewed.

  FIG. 4 schematically shows an example of a configuration for drawing a pattern of the laser perforation 2 corresponding to the binarization pattern of the Fourier transform image of the image in the laser perforation region 1 of the information recording medium 10. For example, laser light from an infrared laser 12 such as a YAG laser is incident on an optical modulator 13 such as an AOM. A computer 20 is connected to the optical modulator 13 via a driver, and the computer 20 stores the binary data as described above of the Fourier transform image of the image to be recorded. The light modulator 13 is controlled to be turned on corresponding to the pixel to be opened. The laser beam that has passed through the optical modulator 13 enters an optical deflector 14 such as a polygon mirror, and directs the laser beam to the corresponding pixel position. The laser beam deflected by the optical deflector 14 is converted into a focused laser beam 16 by the condenser lens 15, and the focused laser beam 16 is focused at a predetermined pixel position of the information recording medium 10 to open the laser perforation 2. This is shown in FIG.

  In the arrangement of FIG. 4, the pixel position in the XX direction (direction perpendicular to the drawing) of the information recording medium 10 is selected by deflection by the optical deflector 14, and the YY direction parallel to the drawing of the information recording medium 10 is used. These pixel positions can be selected by moving the information recording medium 10.

As described above, according to the information recording medium having the micro-perforated pattern of the present invention, and the production method and recognition method thereof:
(1) A binarized image is formed by laser drawing on the surface of the medium by Fourier transforming a pattern such as a logo. In this case, the hole formed by the laser beam surely penetrates.
(2) When the point light source is observed through the binarized image formed by this perforation pattern, the image is reproduced. By observing the image, the authenticity of the medium can be determined.
(3) One of the perforations (dots) by laser drawing is so small that it cannot be recognized by the naked eye. Therefore, when the medium is viewed from the side opposite to the point light source, the light can be recognized as being transmitted (the opposite side of the medium). When the point light source with high brightness is illuminated, the dots are formed at predetermined intervals).
(4) Since the binarized and drawn image data has an arbitrary pattern (eg, logo, company name, barcode, etc.) Fourier-transformed, it is a meaningless pattern with the naked eye, and is a minute pattern. It is unknown to the general public whether or not there exists.
(5) Since it is manufactured by a laser drawing apparatus, an arbitrary pattern can be concealed and recorded if it is a scanning laser drawing apparatus. If the drawing method is a batch drawing, a fixed pattern is recorded, but mass production becomes easy.
(6) A binarized image formed by Fourier transform can be recorded on any medium such as paper or plastic sheet as long as it can be perforated with laser light.
(7) If the person in charge is educated about the authentication method (recognition method), it can be recognized even when using illumination light in a familiar environment, and thus the use of an authentication device is not necessary.
(8) Since a laser drawing apparatus is used, it is excellent in mass productivity. Conventionally, a Fourier transform pattern is generally formed by a photolithography method using a resist or a positive film for printing plate making, and the process is complicated. Can be drawn on a medium.

It is a figure which shows the example of the information recording medium produced based on this invention. It is a figure which shows a mode that the image recorded as a Fourier-transform image from the information recording medium produced based on this invention is reproduced | regenerated and observed. It is a figure which shows the example of the image which can be visually recognized to record, and the amplitude image of the Fourier transform image of this image. It is a figure which shows typically an example of the structure for drawing the pattern of the laser drilling corresponding to the binarization pattern of the Fourier-transform image of an image in the laser drilling area | region of an information recording medium. It is sectional drawing which shows a mode that a focused laser beam converges on the predetermined pixel position of an information recording medium, and a laser perforation is opened.

Explanation of symbols

E ... observer's eye 1 ... laser perforation region 2 ... laser perforation 3 ... reproduced image 10 ... information recording medium 11 ... point light source 12 ... infrared laser 13 ... light modulator 14 ... light deflector 15 ... condensing lens 16 ... focusing Laser light 20 ... computer

Claims (5)

The phase image or amplitude image of the Fourier transform image of the original image is divided into pixels and binarized according to the phase value or amplitude value, and penetrates the medium to the medium position of the pixel corresponding to one of the binarized values. An area in which a perforation is provided and a pixel position corresponding to the other value is recorded without a perforation, and an area where the Fourier transform image is recorded by the perforation is an area where visible pattern information is recorded An information recording medium having a microperforation pattern, wherein the information recording medium is arranged so as to overlap all or a part of the recording medium. Wherein the range of pixels each longitudinal and lateral dimensions of 5 to 50 [mu] m, the information recording medium having a small drilling pattern according to claim 1, wherein said perforations, characterized in that the range of diameters 2.5～25Myuemu. 3. The information recording medium having a micro perforation pattern according to claim 1, wherein the medium is paper or a plastic sheet. The phase image or amplitude image of the Fourier transform image of the original image is divided into pixels and binarized according to the phase value or amplitude value, and penetrates the medium to the medium position of the pixel corresponding to one of the binarized values. open the perforation by irradiation with laser light, micro said Fourier transform image and said Rukoto opened the perforations as region recorded overlap in whole or in part in a region where the visible pattern information is recorded by the perforation A method for producing an information recording medium having a perforation pattern. 5. The method for producing an information recording medium having a micro perforation pattern according to claim 4, wherein the medium is paper or a plastic sheet, and the perforations are perforations having a diameter in the range of 2.5 to 25 [mu] m.

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