JP2006215959A - Information pattern reading/authenticity determining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reading an information pattern and determining its authenticity as a means reading the information pattern recorded on a base material having an infrared ray reflection property by using fluorescent ink, which is excited by an infrared ray in a specific wavelength area to emit an infrared ray with a peak wavelength different from that of the excitation wavelength. <P>SOLUTION: When a pattern recording area including the information pattern on the base material is irradiated with an infrared ray, a reflection factor in a part having the information pattern (an information pattern existing part) is lowered in comparison with a part having no information pattern since the infrared ray is absorbed in an excitation wavelength area to the fluorescent ink. Using this phenomenon, the information pattern in the pattern storage area is read, while when emission of the infrared ray from the information pattern existing part is detected, authenticity of the information pattern is determined. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention reads an information pattern recorded using fluorescent ink that emits infrared light having a peak wavelength different from the excitation wavelength when excited by infrared light in a specific wavelength region on a substrate having reflectivity with respect to infrared light. And a method of performing authenticity determination.

  Conventionally, in order to prevent counterfeiting and maintain confidentiality, a fluorescent ink containing a fluorescent material that is excited by infrared irradiation and emits fluorescence having a wavelength different from the central wavelength of the irradiation light is used to make paper, plastic, metal, etc. An invisible bar code (so-called stealth bar code) that cannot be seen with the naked eye is printed on the base material of the article, and the printed matter is irradiated with the infrared light to optically detect the fluorescence emitted from the bar code part. By doing so, a technique that enables reading of code information is known (for example, Patent Document 1). According to this, the barcode cannot be read with the naked eye, and unless the fluorescence emitted from the barcode portion is optically detected by irradiating the barcode, the information cannot be read. As compared with the case where a visible bar code is formed with this ink, security can be improved.

  On the other hand, in recent years, there are many occasions where a two-dimensional code such as a QR code (registered trademark) that can have more information than a one-dimensional code such as a conventional barcode is used. In the case where a predetermined information pattern is recorded at a relatively high density in the vertical and horizontal directions such as this two-dimensional code, infrared excitation and red light emitted by infrared irradiation in a specific wavelength region as in the one-dimensional code. It is difficult to adopt a method (hereinafter referred to as “infrared excitation / infrared light emission reading method” as appropriate) in which an information pattern is formed using an external light emitting fluorescent material and the light emission (fluorescence) is read. Since the fluorescence from the part where the information pattern is formed on the substrate, that is, each part where the fluorescent substance exists, is emitted in all directions, the infrared emission intensity distribution corresponding to the information pattern can be optically detected This is because it is extremely difficult (it is difficult to obtain a sufficient resolution necessary for reading an information pattern).

  For this reason, in those having a predetermined pattern in the vertical and horizontal directions, such as a two-dimensional code, using an infrared absorber that has high light transmission in the visible light region and absorbs in the infrared wavelength region, An information pattern that is invisible to the naked eye is recorded on a base material that is reflective to visible light and infrared light (for example, Patent Document 2). In this case, in the portion where the information pattern recorded using the infrared absorber exists, absorption by the infrared absorber occurs when the infrared ray in the specific wavelength region is irradiated, and the intensity of the reflected light is reduced accordingly. From this, a method of reading the information pattern formed on the substrate by detecting the intensity (reflectance) of the infrared reflected light (hereinafter referred to as “infrared excitation / infrared absorption reading method” as appropriate) Taken.

JP-A-7-27189 JP 2000-6512 A (page 2)

  However, in the infrared excitation / infrared absorption reading method as described above, the true information pattern and the pattern are the same using an ink having absorption in an infrared region different from the fluorescent ink for forming the original information pattern ( Even if the printed information is printed or copied, and if the ink used exhibits infrared absorptivity over a wide wavelength region, the information pattern recording region is irradiated with infrared rays. Sometimes infrared absorption seen in the original information pattern is also detected in the false information pattern. Therefore, just reading the information pattern by detecting the infrared absorption or infrared reflection of the information pattern existing part, is it a true information pattern recorded using the original fluorescent ink, or what is the original fluorescent ink? It is impossible to know whether the information pattern is a fake information recorded using different ink.

  The present invention addresses such problems, and is a fluorescent ink that emits infrared rays having a peak wavelength different from the excitation wavelength when excited by infrared rays in a specific wavelength region on a substrate having reflectivity with respect to infrared rays. An object of the present invention is to provide a method capable of determining not only the reading of an information pattern but also its authenticity when reading an information pattern recorded by using.

  In order to achieve the above object, the present invention uses a fluorescent ink that is excited by infrared rays in a specific wavelength region and emits infrared rays having a peak wavelength different from the excitation wavelength on a substrate having reflectivity with respect to infrared rays. In the method of reading the information pattern recorded in this way and determining the authenticity, the following configuration is provided.

  That is, when a pattern recording region including an information pattern on a substrate (a predetermined region on the substrate on which the information pattern is recorded) is irradiated with infrared rays, the portion where the information pattern exists (information pattern existing portion) is fluorescent ink. By utilizing the fact that absorption of infrared rays occurs in the excitation wavelength region with respect to the infrared rays, the reflectance of the infrared rays becomes lower than that of the portion where no information pattern exists (the portion where no information pattern exists). While reading the pattern, the presence or absence of infrared light emission from the information pattern existing portion is detected, and the authenticity of the information pattern is determined based on the detection result. Specifically, the pattern recording area is irradiated with infrared light of a specific wavelength region, and when the infrared light emitted from the fluorescent ink is detected from the information pattern existing portion, the information pattern is determined to be true, and such infrared light is detected. If not, the information pattern is determined to be false.

  The information pattern to be read by the method of the present invention is recorded using a fluorescent ink having an absorption peak at a wavelength of 800 nm to 850 nm, or a fluorescent ink excited by an infrared ray having a wavelength of 800 nm to 850 nm and emitting an infrared ray having a wavelength of 950 nm to 1000 nm. It is preferable that This is due to the following reason. That is, although it is possible to change these wavelengths to some extent if the material is changed, it is desirable that the interval between the excitation and emission wavelengths be 100 to 200 nm apart in order to perform reliable optical reading. On the other hand, the excitation light source and the light receiving element become expensive because they are not general components when their light emission and light receiving sensitivity wavelength regions exceed 1000 nm. Under these conditions, when the usable invisible wavelength region is set to 750 to 1000 nm, the wavelength characteristics of the light emission / light reception sensitivity of the existing optical component and the excitation / emission wavelength region of the phosphor material As a result of considering the combination characteristics, it has been concluded that it is preferable to record the information pattern using the fluorescent ink having the optical characteristics as described above.

  According to the present invention, when the pattern recording area on the substrate is irradiated with infrared rays, the information pattern is read by the intensity of the infrared reflected light generated in each part of the pattern recording area, so that a complicated pattern can be formed in the vertical and horizontal directions. The information pattern can be read comparatively well even for a two-dimensional code having the same. At the same time, it is possible to easily determine the authenticity of the read information pattern by detecting the presence or absence of infrared light emission from the information pattern existing portion in the pattern recording area.

  The method of the present invention can also be used as a means for determining the reading and authenticity of a relatively simple information pattern such as a one-dimensional barcode. However, it is more effective to apply this method to reading and authenticating relatively complicated information patterns such as a two-dimensional code that is difficult to determine authenticity.

  The information pattern to be read by the method of the present invention is recorded on a substrate using a fluorescent ink that is excited by infrared rays in a specific wavelength region and emits infrared rays having a peak wavelength different from the excitation wavelength. The phosphor used in the fluorescent ink in this case has an absorption peak at a wavelength of 800 nm to 850 nm as described above, particularly one that emits an infrared ray at a wavelength of 950 nm to 1000 nm when excited by an infrared ray at a wavelength of 800 nm to 850 nm. preferable. Examples of such phosphors include those described in Japanese Patent Application Laid-Open No. 8-151545 related to the prior application of the applicant of the present application. Specifically, for example, the following phosphors are used.

  A phosphor having at least Nb or Yb as an optically active element and containing at least one oxide of Mo or W and an alkaline earth metal in addition to the optically active element (hereinafter referred to as “specific phosphor”) "). The average particle size of the specific phosphor is preferably 1 μm or less.

  In the specific phosphor, the atomic ratio s of the optically active element with respect to at least one oxide of Mo or W is set to 0 <s ≦ 2.

  In the specific phosphor, an atomic ratio t of alkaline earth metal to at least one oxide of Mo or W is set to 0 <t ≦ 3.

A specific phosphor comprising a compound having the following general formula (9).
General formula (9)
_{(Nd 1-X Yb X)} Y Q Z (RO 4)
Wherein Q is at least one element selected from the group of Ca, Mg, Sr, Ba, R is at least one element selected from the group of Mo, W, X is a numerical value in the range of 0 to 1, Y is a numerical value greater than 0 and less than 1, and Z is a numerical value greater than 0 and less than or equal to 1.

A specific phosphor comprising a compound having the following general formula (10).
General formula (10)
(Nd _1-X Yb _X ) _2Y Q _8-3Y (RO ₄ ) ₈
Wherein Q is at least one element selected from the group of Ca, Mg, Sr, Ba, R is at least one element selected from the group of Mo, W, X is a numerical value in the range of 0 to 1, Y is a numerical value in the range of more than 0 to 8/3.

  In the specific phosphor, X in the general formula (10) is a numerical value in the range of 0.02 to 0.6, and Y is a numerical value in the range of 1/3 to 5/3.

  In the specific phosphor, the alkaline earth metal is Ca.

Such a phosphor can be manufactured by the following method described in JP-A-8-151545. That is, T ₂ O ₄ .nH ₂ O (wherein T is at least one element selected from the group of Li, Na and K, R is at least one element selected from the group of Mo and W, n is a numerical value of 0 or more), and at least one optically active element of Nd or Yb, at least one oxide of Mo or W, and an alkaline earth metal are added. After firing, the flux material is dissolved and removed with a solvent. In this case, it is preferable that T of the flux material is Na and R of the flux material is Mo, and the mixing molar ratio of the flux material to the phosphor material is preferably regulated within a range of 1 to 10.

  An information pattern suitable for reading by the method of the present invention can be formed, for example, by printing on a substrate having reflectivity with respect to infrared rays using a fluorescent ink containing the above-described phosphor. An example of the printed matter formed in this way is shown in FIG. In the printed matter 1 illustrated in FIG. 1, a white paperboard 13 is used as a base material, and an information pattern 11 composed of a two-dimensional code is formed thereon by offset printing. Further, on the white plate 13 on which the information pattern 11 is formed, offset printing is performed using four process inks having infrared transparency (indigo, red, yellow, black; however, inks that do not contain carbon black). A formed color image layer 12 is provided.

  Examples of the substrate having reflectivity with respect to infrared rays include white paper, a white film printed on a plastic film, and the like. Examples of the plastic film in this case include polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and synthetic paper. Although it is considered that there is an advantage of paper and film depending on the use of the finished product, which is not generally good, in the embodiment of the present invention to be described later, white paper was selected because of its low cost and ease of handling. However, the substrate is not limited to these, and any substrate may be used as long as it has infrared reflectivity and can record an information pattern.

  Next, an information pattern reading apparatus used in the information pattern reading / authentication determination method according to the present invention will be described. FIG. 2 shows an example of the configuration of an information pattern reading / authentication determining device used in the method of the present invention.

  This information pattern reading / authentication determining device has an information pattern reading portion and an authenticity determining portion. Among these, the information pattern reading portion takes a light signal and converts it into an electric signal, for example, a photoelectric conversion element portion 14 made of a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and the electric signal as code information. A decoding circuit 20 for converting the data into a signal, a data processing unit 21 for determining and processing the code information in response to outputs from the decoding circuit 20 and an amplifier circuit to be described later, and a red arranged in front of the photoelectric conversion element unit 14. For example, the information pattern is irradiated with predetermined light in order to reproduce the intensity of reflected light of the information pattern recorded on the printed matter 1 shown in FIG. A light source 16 composed of a light emitting element such as a semiconductor laser (LD) or a light emitting diode (LED) and a predetermined voltage corresponding to the detection timing of the information pattern. A driving power source (driving circuit) 22 of the light source such as a drive to force a configuration in which an optical filter portion 17 of the light of a predetermined infrared region disposed in front of the light source 16 selectively pass.

  On the other hand, the authenticity determination portion takes light emitted from the phosphor at a position irradiated from the light source 16 and converts it into an electrical signal, for example, a photoelectric conversion element portion 18 made of a photodiode (PD), and a front surface of the photoelectric conversion element portion 18. The optical filter unit 19 that selectively passes light in a predetermined infrared region that is arranged, and an amplifier circuit 23 that amplifies the electrical signal converted by the photoelectric conversion element unit 18 to a predetermined size. .

  The photoelectric conversion element 14 has a sensitivity particularly in the vicinity of a wavelength of 800 to 850 nm, and the photoelectric conversion element 18 has a light receiving sensitivity in the near infrared region, particularly a wavelength of 1000 nm. Are used that have a peak emission wavelength in the vicinity of 800 to 850 nm.

  First, a printed matter A on which a genuine information pattern as described below was formed and a printed matter B on which a fake (copy) information pattern was formed were prepared. The printed materials A and B are produced as described below using the materials described later. Since these layer structures are the same as those of the printed material 1 shown in FIG. FIG. 1 is used in describing each part of FIG. Further, the information pattern reading / authentication determining device (see FIG. 2) described above was used to perform the information pattern reading / authentication determination on these printed materials A and B.

<< Print A >>
A UV resin and a UV initiator having the following compositions were prepared in advance as materials for preparing a fluorescent ink, which will be described later.
<UV resin>
・ Photomer 6008 (manufactured by Inabata Sangyo Co., Ltd.) 54 parts by weight ・ Neomer DA600 (manufactured by Sanyo Kasei Co., Ltd.) 33 parts by weight ・ EA 1020 (manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts by weight ・ MR260 (manufactured by Daihachi Chemicals) 3 parts by weight <UV Initiator>
IR907 (Miki Sangyo Co., Ltd.) 40 parts by weight Darocur 1173 (Nagase Sangyo Co., Ltd.) 60 parts by weight

A specific phosphor (43 parts by weight) described above and the above UV resin (45 parts by weight) on a base material 13 (Hokuetsu Paper Co., Ltd .: N-W 360 g / m ² ) as shown in FIG. Then, 12 parts by weight of the UV initiator was added, and the mixture was stirred for 5 minutes to prepare a fluorescent ink that emits infrared light by infrared excitation. Here, as the specific phosphor, in the compound represented by the general formula (10), that is, (Nd _1−X Yb _X ) _2Y Q _8-3Y (RO ₄ ) ₈ , Ca is preferably used as Q. In addition, Mo is used as R, and phosphors having compositions in which the subscripts “X” and “Y” are numerical values in the range of 0 <X <1, 0 <Y <8/3, respectively. did.

  Using this fluorescent ink, an information pattern 11 is formed on the base material 13 by offset printing, and then, on the base material 13 on which the information pattern 13 is formed, four colors of process inks (indigo and indigo) have the property of transmitting infrared rays. Red / Yellow: Best Cure UV 161 S series manufactured by TOKA, Black: Best Cure UV NVR series manufactured by TOKA) are used for offset printing, and the desired layer structure as shown in FIG. A print A having

  In the obtained printed matter A, since the printing layer is formed by offset printing, the thickness of each ink is as thin as about 1 to 2 μm, and there are almost no steps due to pattern formation. For this reason, it is difficult to confirm the information pattern 11 from the surface shape, and the ink forming the information pattern 11 is pale light blue, and the color image 12 covers this, so it is difficult to confirm the color.

《Printed matter B》
On the other hand, as the printed matter B, a black ink (made by TOKA; Best Cure UV NVR series) having the same layer configuration as the printed matter A (see FIG. 1) and containing carbon black is different from the printed matter A only in the information pattern 11. To produce an offset printed product. In the obtained printed matter B, even if a color image was printed from above, the pattern could be almost completely hidden (observation result with the naked eye).

<Reading information pattern>
In the information pattern reading / authentication determination apparatus shown in FIG. 2, a CCD camera (Matsushita Electric Works; AN832) is used as the photoelectric conversion element unit 14, and a long wavelength cut filter (an optical filter unit 15 is provided on the lens front surface). Asahi Spectroscopic Co., Ltd .; SI0840) 15-1 and a short wavelength cut filter (Asahi Spectroscopic Co., Ltd .; LI0810) 15-2 were attached. FIG. 3 shows the optical characteristics of the long wavelength cut filter 15-1 and the short wavelength cut filter 15-2 used in this case.

  Next, a light source having a light emission peak in the vicinity of 800 nm with respect to the printed matter A on which the information pattern 11 is formed, via an optical filter unit 17 having both long-wavelength and short-wavelength cut filters similar to the optical filter unit 15. (LED here) 16 was irradiated. As a result, a color image by the process ink could not be read, and only the information pattern 11 that appeared black by identifying the light from the light source 16 could be identified.

  Similarly, when the printed matter B on which the information pattern 11 is formed is irradiated with light from the light source 16, the color image by the process ink cannot be read and the light from the light source 16 becomes black as in the printed matter A. Only visible information pattern 11 could be identified.

《Authenticity judgment of information pattern》
Next, in order to determine whether the information pattern 11 in the printed matter A and B is genuine or fake, the information pattern forming portion of the printed matter A and B is irradiated with light having a light emission peak in the vicinity of 800 nm from the light source 16 (LED). Irradiated. Then, the photoelectric conversion element 18 (here, PD) provided with a high-pass filter (manufactured by Asahi Spectroscopic Co., Ltd .; LI0960) as the optical filter unit 19 to which the reflected light from these information pattern formation portions is input. When the presence or absence of light emission from 960 nm to 1000 nm or less was detected, light emission was not detected in the printed matter B, and only the light emission output could be detected in the printed matter A. Thus, it was possible to determine that the information pattern in the printed matter A was genuine and the information pattern in the printed matter B was fake.

  FIG. 3 also shows the optical characteristics of the high-pass filter (manufactured by Asahi Spectroscopic Co., Ltd .; LI0960) used as the optical filter unit 19 in this case.

Sectional drawing which shows typically an example of the printed matter on which the information pattern read by the method of this invention was recorded. The block diagram which shows the example of 1 structure of the information pattern reading / authentication determination apparatus used with the method of this invention. The spectrum figure which shows the optical characteristic (relationship between a light transmittance and a wavelength) of each optical filter used in the Example of this invention.

Explanation of symbols

1 Printed matter 11 Information pattern 13 Base material

Claims (3)

Reading and authenticating information patterns recorded using fluorescent ink that emits infrared light whose peak wavelength is different from the excitation wavelength when excited by infrared light in a specific wavelength region on a substrate that is reflective to infrared light A way to do,
When the pattern recording area including the information pattern on the substrate is irradiated with infrared rays, the information pattern existing portion is read while reading the information pattern in the pattern recording area using the difference in intensity of reflected light depending on the presence or absence of the information pattern. An information pattern reading / authentication determining method, wherein the authenticity of the information pattern is determined by detecting the presence or absence of infrared emission from the information pattern.   The information pattern reading / authentication determination method according to claim 1, wherein the information pattern is recorded using fluorescent ink having an absorption peak at a wavelength of 800 nm to 850 nm.   3. The information pattern reading / authentication determination method according to claim 1, wherein the information pattern is recorded using fluorescent ink that is excited by infrared rays having a wavelength of 800 nm to 850 nm and emits infrared rays having a wavelength of 950 nm to 1000 nm.

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