JP4670561B2 - Laminated sheet - Google Patents

Description

  The present invention relates to the field of information security, and in particular, relates to a laminated sheet provided with confidential information for personal authentication such as a passport or an ID card.

  2. Description of the Related Art Conventionally, proof articles with personal authentication, such as passports and various ID cards, are commonly used with face photographs. In particular, when it is applied to security, there is a problem that authentication must be made possible by identifying an individual.

  In recent years, in addition to visible information such as facial photographs, invisible information has been recorded on many proof articles. Invisible information recording methods have been put to practical use, such as magnetic properties such as magnetic ink, light transmission properties such as invisible ink with high transparency in the visible light region, and light emission properties such as fluorescent ink that emits light by ultraviolet irradiation. ing. The invisible information is recorded on the card surface by the printing method in the card manufacturing process. The personal authentication data is added in the issuing business, and the visible information includes a face photograph, a name, and the like. Invisible information is recorded on a magnetic stripe or IC chip.

  However, fraudulent use due to counterfeiting and tampering continues. Therefore, holograms, diffraction gratings, micro characters, and the like have been used as identification information by using microfabrication technology in order to provide further security. Since the existence of these can be easily confirmed, the fine structure can be forged relatively easily, so the information contents have to be updated sequentially. Therefore, a further information recording method that replaces the conventional security has been desired.

  And as one of the methods of providing information that is difficult to forge, there is a method disclosed in Patent Document 1. According to this, on the image forming area on one side of the plastic base material layer containing the pigment that changes color when irradiated with laser light, an image processed by encryption is formed by irradiating the laser light and changing the color tone of the material. Has been proposed.

  However, this method has a drawback of requiring a special material for changing the color.

  As another example of forgery prevention, there is a method disclosed in Patent Document 2. A rewritable reversible display part is provided on a part of the card, and the shape of the reversible display part is made into an optically distinguishable pattern when in the display state, and transparent when not in the display state. It was made invisible under light. The material used for the reversible display portion is a leuco dye containing an olfuran dye and a long-chain alkylphenol type reversible developer, or a fatty acid-polymer composite material in which a fatty acid is dispersed in a polymer compound.

  However, since the information on the reversible display section is information representing card attributes and is printed in the card manufacturing process, there is a problem that personal authentication data cannot be given.

By the way, in recent years, it has been proposed to use an ultrashort pulse laser of 1 picosecond or less for precision processing of the depth of an organic compound. In particular, non-thermal processing is possible due to phenomena such as multiphoton absorption and thermal relaxation time, and processing resolution is below the diffraction limit of light due to non-linear response. Is known (see, for example, Non-Patent Document 1).
JP 2002-086967 A JP 2003-154778 A Katsumi Midorikawa, “Femtosecond laser interaction with matter”, Journal of Laser Processing, 2001, Vol. 8, No. 3

  The present invention has been made in consideration of the background art as described above, and provides a laminated sheet in which confidential information that is extremely difficult to forge or counterfeit is added to an image or text for personal authentication. Let it be an issue.

Means provided by the invention to solve the above-mentioned problems are as follows. First, as shown in claim 1, at least a color material layer on which invisible information is recorded on a substrate, and a transparent covering the color material layer A laminated sheet in which a protective layer is laminated, wherein the invisible information is recorded by condensing a laser beam on a color material layer , and pulverizing or decomposing the color material to erase the color material. It is a laminated sheet to do.

  This makes it possible to provide a laminated sheet to which secret information that is difficult for a cardholder to notice the presence of information and difficult to find with a magnifying glass is provided.

  According to a second aspect of the present invention, in the laminated sheet according to the first aspect, the laser is an ultrashort pulse laser having an oscillation pulse width of 1 picosecond or less.

  Since this ultrashort pulse laser does not affect the laminated sheet thermally, it is possible to provide a laminated sheet in which only the inside of the sheet is processed without damaging the protective layer. In addition, the ultrashort pulse laser has very little dependence on the light absorption characteristics of the material, and there is no need to select a material that matches the laser wavelength.

  Further, as described in claim 3, an IC chip having a memory circuit is mounted, and the recording position of the invisible information is stored in the memory circuit. It is a laminated sheet.

  Thereby, since the recording position of the secret information set arbitrarily can be protected by the encryption key, unauthorized use of the secret information can be made extremely difficult.

  Further, as shown in claim 4, the invisible information is represented by a character string, and the character string is encrypted. It is a sheet.

  This makes it difficult to falsify even if the recorded information is found.

  Moreover, as shown in claim 5, the key relating to the encryption of the character string is stored in the storage circuit, and the laminated sheet according to claim 4 is characterized in that.

  As a result, a double key can be hooked, so that security can be improved.

According to a sixth aspect of the present invention, the color material layer is formed by color superimposition of pigment ink using a pigment ink thermal transfer printer, and the invisible information erases a specific color by condensing the laser light. The laminated sheet according to any one of claims 1 to 5, wherein the laminated sheet is recorded as described above.

  In this way, the ink after printing is layered, the ink layer configuration is maintained for a long time, only specific colors can be erased, and authenticity can be confirmed for a long time. It is particularly difficult to forge using

  The invention according to claim 1 is advantageous in that it is possible to provide a laminated card to which secret information is given, which is difficult for the card holder to notice the presence of information and difficult to find with a magnifying glass.

  Further, the invention according to claim 2 is a method for forming fine figures and characters on the ink of a laminated sheet in which a printing layer and a transparent protective layer are laminated on a substrate with an ultrashort pulse laser having an oscillation pulse width of 1 picosecond or less. There is an effect that it is possible to provide a laminated sheet in which invisible information including rows is written. As a result, there is an effect that it is possible to provide a laminated sheet to which secret information that is difficult for a card holder to notice the presence of information and difficult to find with a magnifier can be provided. In addition, since this ultrashort pulse laser does not affect the laminated sheet with heat, there is an effect that it is possible to provide a laminated sheet in which only the inside of the sheet is processed without damaging the protective layer. In addition, the ultrashort pulse laser has a very small dependence on the light absorption characteristics of the material, and it is not necessary to select a material according to the laser wavelength, so that an inexpensive material can be used.

  According to a third aspect of the present invention, the laminated sheet has an IC chip mounted thereon, and the storage position of the invisible information is stored in the storage circuit of the IC chip, whereby the recording position of the secret information set arbitrarily is encrypted. Therefore, the unauthorized use of confidential information can be made extremely difficult.

  Further, the invention of claim 4 has an effect that it is difficult to tamper with the recorded information even if it is found by encrypting the character string as the invisible information.

  Further, the invention of claim 5 improves security by storing a key relating to encryption of a character string as invisible information in a storage circuit of the mounted IC chip so that a double key can be applied. There is an effect that can be done.

  In the invention of claim 6, the ink after printing is layered, the ink layer configuration is maintained for a long time, only a specific color can be erased, and the authenticity can be confirmed for a long time. There is an effect that counterfeiting using a general printer is particularly difficult.

  As described above, the present invention has an effect that it is possible to provide a laminated sheet in which confidential information that is extremely difficult to forge or counterfeit is added to an image or text for personal authentication.

  The best embodiment of the present invention will be described below.

  In the present invention, a color material layer containing a pigment or a dye is provided on a paper or plastic substrate, and the color material layer of the laminated sheet in which the color material layer is covered with a plastic transparent protective layer is focused on. When an ultrashort pulse laser of 1 picosecond or less is irradiated, information is recorded by erasing the color material by crushing or decomposing only the color material through the transparent protective layer.

  By irradiating a transparent body with an ultrashort pulse laser of 1 picosecond or less, the inside of the transparent body can be modified without damaging the surface of the transparent body.

  Since the size of the decoloring area can be controlled with sub-micron digits, information can be recorded with a resolution of one digit or more as compared with conventionally used micro characters and images.

  In general, since the pixel size of a printed material is several tens of μm, it is realistic to record a plurality of micrometer size characters in one pixel using an ultrashort pulse laser of 1 picosecond or less.

  Although reading requires a microscope system, information indicating the laser-recorded pixel position is stored in advance in another means such as a magnetic stripe, an optical memory, an IC chip, and the position information is referred to at the time of reading. For data communication with the IC chip, a contact type terminal may be provided, or a non-contact type transmission means may be provided.

  Furthermore, the confidentiality of information can be improved by encrypting the information recorded in the pixels.

  The decryption key for encryption is stored in another means, for example, a magnetic stripe, an optical memory, an IC chip, etc., similarly to the pixel position information recorded by the laser.

  FIG. 1 is an example of a method for recording invisible information inside a laminated sheet by an ultrashort pulse laser according to the present invention, and is a schematic diagram showing a method for writing confidential information to a passport booklet by an ultrashort pulse laser. . Moreover, FIG. 2 is a figure which shows the writing of the confidential information to the passport booklet by the ultrashort pulse laser which concerns on this invention.

  For processing, a femtosecond laser apparatus having an oscillation wavelength of 775 nm, a peak power of 800 mW, a pulse energy of 800 μJ / pulse, a pulse width of 200 femtoseconds, a pulse repetition frequency of 1 kHz, and an optical beam spot diameter of 10 μm was used.

  The personal authentication sheet of the passport booklet 8 is an image portion (face photograph) formed by laminating and forming at least four colors (yellow, magenta, cyan, black) of ink 3 on the surface of the paper substrate 2 with a pigment ink thermal transfer printer (not shown). 12 and a protective layer 4 is laminated thereon. The ink 3 is made of a butyral resin and a pigment, and the thickness of the ink layer is about 0.5 μm. The protective layer 4 is a urethane resin and has a thickness of 5.5 μm.

  The laser beam 5 is focused to an optical radius of 10 μm at the position of the ink 3 by the condenser lens 6. At this time, an enlarged image of the recording information 11 in the pixel 10 is observed by a CCD monitor camera (not shown).

  First, the surface position of the protective layer 4 of the passport booklet 8 is measured, and then the focus of the laser beam 5 is adjusted to the black depth of the ink 3.

  Then, the XYZ stage 7 is driven by a program created according to the machining information produced based on the design information, and laser is irradiated.

  The dimension of the pixel 10 of the gradation image of the face photograph printed on the passport booklet 8 used in this embodiment is about 80 μm.

  The position of the pixel 10 to be recorded is designated from the bitmap information of the image, and an encrypted character string having a line width of 1 μm to 2 μm and a character height of 10 μm is recorded in the pixel 10 (see FIG. 2).

  As a result, only the black of the ink 3 is crushed and decolored without damaging the protective layer 4, thereby recording information 11 that is difficult to confirm visually or with a magnifying glass is recorded in the pixels 10 of the gradation image. Obtained.

  Further, the position information of the pixel 10 and the decryption key information of the recording information 11 are stored in the storage circuit of the IC chip 9 having non-contact type transmission means embedded in the passport booklet 8.

It is the schematic which shows the recording method of the invisible information inside the lamination sheet by the ultrashort pulse laser concerning this invention. It is a figure which shows the writing of the confidential information to the passport booklet by the ultrashort pulse laser which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laminated sheet 2 ... Paper base material 3 ... Ink (yellow, magenta, cyan, black)
DESCRIPTION OF SYMBOLS 4 ... Protective layer 5 ... Laser beam 6 ... Condensing lens 7 ... X, Y, Z stage 8 ... Passport booklet 9 ... IC chip 10 ... Pixel 11 ... Recording information 12 ... Image part (face photograph)

Claims (6)

A laminated sheet in which at least a color material layer on which invisible information is recorded and a transparent protective layer covering the color material layer are laminated on a base material, and the invisible information collects laser light on the color material layer. A laminated sheet, which is recorded by pulverizing or decomposing and discoloring the coloring material by illuminating. The laminated sheet according to claim 1, wherein the laser beam is an ultrashort pulse laser having an oscillation pulse width of 1 picosecond or less.  The laminated sheet according to claim 1 or 2, wherein an IC chip having a memory circuit is mounted, and the recording position of the invisible information is stored in the memory circuit.  The laminated sheet according to any one of claims 1 to 3, wherein the invisible information is represented by a character string, and the character string is encrypted.  The laminated sheet according to claim 4, wherein a key related to encryption of the character string is stored in the storage circuit. The color material layer is formed by color superimposition of pigment ink using a pigment ink thermal transfer printer, and the invisible information is recorded by erasing a specific color by condensing the laser light. Item 6. The laminated sheet according to any one of Items 1 to 5.