JP2005100003A - Information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium capable of recording a plurality of pieces of information in the same area, and adapting to even a small-size handy type reader having low power consumption. <P>SOLUTION: In this information recording medium, visual information or machine reading information is formed on a base material by use of an ink composition mainly consisting of a phosphor. As the phosphor, two or more kinds of phosphors having nearly same excitation wavelengths and different emission wavelengths are used. Above all, the pieces of information formed with the two or more kinds of phosphors are desirable to be pieces of information showing different contents respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information recording medium using a phosphor.

  More specifically, for example, counterfeit prevention measures (forgery detection and deterrence), genuine products such as gift certificates and (credit) cards, etc. Anti-counterfeiting measures (forgery detection and deterrence) for machine authentication (for example, there are many hopes for application to expensive products such as brand products and luxury products) The present invention relates to an information recording medium provided.

  A method for forming an image on a substrate using a phosphor has been known for a long time. For example, an image is formed on a banknote or a credit card with a phosphor having ultraviolet light as an excitation wavelength, and visualized by irradiation with black light.

  Several methods have been proposed for recording machine-readable information using such phosphors.

  There has been proposed a method of recording multiple information by superposing phosphors and ordinary printing ink. This means that information formed by a color (for example, red) that efficiently reflects a wavelength of 600 nm or more as printing ink and information formed by a phosphor that excites and emits light by a wavelength of 600 nm or less are printed in an overlapping manner. Thus, double information is recorded in the same print area. At the time of reading the recorded information, detection of reflected light by a light source of 650 nm and detection of light emission by light irradiation with an excitation wavelength of the phosphor are performed. Thereby, separate record information can be read.

  As another method, two or more kinds of phosphors having different excitation light wavelengths and emission wavelengths are used, and different pieces of information are recorded as machine reading information, and light is emitted from light sources of the respective excitation wavelengths. A method has been proposed in which the emitted light is read using an optical filter that transmits only the respective emission wavelengths. Similarly, double information can be recorded in the same print area.

JP 7-21333 A (page 2) Japanese Patent Laid-Open No. 9-161002 (2nd page)

  However, the above-described technique has a problem that in order to read the recorded information, the information recording unit must be irradiated with light passing through different light sources or filters. Therefore, at least the number of recording materials required for the device that emits light serving as the light source is necessary, which causes the reading apparatus to become enlarged.

In particular, in realizing a portable handy reading apparatus, it is preferable that the number of devices of the light emitting unit is as small as possible from the viewpoint of miniaturization. Further, since a battery or a dry cell is often used as a power source, it is preferable that power consumption be as low as possible. The fact that there are a plurality of light sources will undoubtedly lead to an increase in power consumption, and it must be said that this is also a problem.

  The present invention has been proposed in view of the above-mentioned problems of the prior art, and its purpose is to be able to record a plurality of information in the same area, and to be a handy type that is downsized and consumes low power. An information recording medium corresponding to the reading apparatus is provided.

  The present invention solves this problem, and the invention according to claim 1 is an information recording medium in which visual information or machine-readable information is formed on a substrate using an ink composition mainly composed of a phosphor. Thus, the present invention provides an information recording medium comprising two or more types of phosphors having substantially the same excitation wavelength and different emission wavelengths.

  The invention according to claim 2 provides the information recording medium according to claim 1, wherein the information formed by the two or more types of phosphors is information indicating different contents. is there.

  3. The information recording medium according to claim 1, wherein at least one of the phosphors is a phosphor that is excited by infrared rays and emits visible light. Is to provide.

  According to a fourth aspect of the present invention, at least one of two or more types of information formed on the base material by the phosphor is machine-readable information that can be machine-readable. The information recording medium according to any one of 3 is provided.

  According to a fifth aspect of the present invention, the machine-reading information is such that light emission cannot be confirmed visually even when a light amount necessary for emitting visible image information is emitted, and is detectable to a reader. The information recording medium according to claim 4, wherein the information recording medium has a light emission amount.

  Since this invention is the above structure, there exist the following effects. That is, by using light sources having the same excitation wavelength, it is possible to provide an information recording medium that can simultaneously read different information recorded in the same area. Moreover, visible information can also be recorded by using a phosphor having an emission wavelength in the visible light wavelength range. Furthermore, by simultaneously recording machine reading information, visual observation of visible information and reading of machine reading information can be performed with a single light source. Furthermore, by reducing the light emission intensity of machine reading information to a level where visual observation is not possible, only visual information is displayed during visual observation, and only machine reading information or both machine reading information and visible information are displayed during machine reading. Can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a front view showing a configuration of an information recording medium 1 according to the present invention. In the information recording medium 1, a first information recording unit 12 and a second information recording unit 13 are formed on a base material 11. In FIG. 1, a person image is provided as the first information recording unit 12 and a barcode is provided as the second information recording unit 13. However, the present invention is not limited to this.

  As the base material 11, conventionally known materials such as paper, plastic, film, wood, glass, and metal can be used.

  Both the first information recording unit 12 and the second information recording unit 13 are information formed by phosphors. As a method for forming information, for example, a method in which an ink in which a phosphor is dispersed in a resin material is printed, coated, or ejected from a nozzle, a method in which a phosphor layer formed on another film is transferred onto a substrate, or vapor deposition And a method of forming by a vapor phase coating method such as sputtering. Resins that can be used for ink-making include general resins such as vinyl resins, acrylic resins, urethane resins, polyester resins, and cellulose resins, thermosetting resins that are added with a crosslinking agent, or UV curing. Conventionally known resins such as resins and photocurable resins such as visible light curable resins can be used. These can be dissolved in a solvent such as a gravure solvent or a screen solvent, and further a phosphor is dispersed to produce a printing or coating ink. However, usable resins are limited to those listed here. It is not a thing. In addition, you may add auxiliary agents, such as a dispersing agent for improving the dispersibility of fluorescent substance, and a leveling agent for improving printability.

  Next, the phosphor used for the first information recording unit 12 and the second information recording unit 13 will be described. The phosphors used in both the recording units are phosphors having substantially the same excitation light wavelength and different emission wavelengths. In addition, the term “almost” as used herein may mean that the excitation peak wavelength may be slightly shifted, and as a result, a combination capable of obtaining a required amount of light emission in detection or visual observation, or a light emission level capable of machine reading is obtained. It means that it should be. The “substantially the same” width here is generally about several tens of nm or less, although it depends on the broadness of the excitation peak wavelength.

  The excitation light wavelength can be selected from long-wavelength infrared light to short-wavelength ultraviolet light according to the phosphor used, and the emission wavelength is required for all phosphors used with the same wavelength light source. It is necessary to set the wavelength to the emitted light intensity. .

  In the present invention, different information can be recorded in the first information recording unit 12 and the second information recording unit 13, respectively. By doing so, two or more types of information can be recorded in the same area.

  In recent years, research on phosphors that emit short-wavelength light with long-wavelength excitation light such as up-conversion fluorescence has been advanced, and it is possible to use this. Specifically, a phosphor that emits visible light using infrared light as excitation light is known. By using a combination of these infrared excitation-visible emission phosphors, information can be confirmed visually.

  Next, the operation of the information recording medium 1 according to the present invention will be described. FIG. 2 is a cross-sectional view of the information recording medium 1 of the present invention cut along XX ′ in FIG. When the information recording medium 1 is irradiated with excitation light 21 (wavelength λ0), both light emission 22 (wavelength λ1) of the first information recording unit 12 and light emission 23 (wavelength λ2) of the second information recording unit 13 are generated. . This is because the excitation wavelengths of the first information recording unit 12 and the second information recording unit 13 are substantially equal. Therefore, although the recorded information is different in the first information recording unit 12 and the second information recording unit 13, they can be reproduced simultaneously with only one light source (= excitation light 21). .

In addition, at the same time, by making one or more of the information recording units formed by a plurality of phosphors into machine-readable information, it is possible to determine authenticity and read out information using a reader. It shows that it is possible. As such machine-readable information, in addition to the barcode shown in the example, information that can be read by optical means such as a conventionally known two-dimensional barcode and OCR characters can be used. In order to read the machine reading information, an appropriate optical filter that irradiates the excitation light 21 and emits the machine reading information out of the obtained light emission, that is, the light emission 23 of the second information recording unit in the above example. By reading through, only light including machine reading information can be taken into the reading device and detected by the sensor to read out the code information.

  In the above-described method of coexisting machine-reading information and visual information, if both information emit light to the same extent and disturb the visibility of visual information, the intensity of the mechanical-reading information cannot be visually observed. By setting the light emission intensity of the visible information separately recorded to be higher than the level where it can be visually observed, it becomes possible to read the information without disturbing the machine reading information at the time of visual observation. FIG. 3 shows this state. In this case as well, the method of reading the machine reading information is the same as described above, and by reading through an appropriate optical filter, only the light containing the machine reading information can be taken into the reading device, and the code information can be read by detecting with the sensor. .

The present invention will be described in detail with specific examples.
A white PET sheet having a thickness of 188 μm was used as the substrate 11. The phosphor for the first information recording unit 12 is a green phosphor having an excitation wavelength of 950 nm and an emission wavelength of 550 nm, and the phosphor for the second information recording unit 13 is red fluorescence having an excitation wavelength of 950 nm and an emission wavelength of 670 nm. Using the body. These were set as shown below, and gravure ink was obtained with a paint shaker.

<Composition of the first information recording part>
-Acrylic resin 18 parts by weight-Green phosphor 2 parts by weight-Gravure solvent 80 parts by weight <Composition of the second information recording part>
-18 parts by weight of acrylic resin-2 parts by weight of red phosphor-80 parts by weight of gravure solvent Subsequently, a PET film original fabric (coating backside) having a thickness of 5 µm by gravure printing using the two types of phosphor inks obtained above. As shown in Table 1, the film was coated with a thickness of 1 μm or 3 μm and slit to obtain printing ribbons for the respective phosphors. When the fluorescence emission intensity of each coated phosphor ribbon was measured with a fluorescence spectrophotometer, the results were as shown in Table 1.

Next, using each printing ribbon, an image was transferred onto the white PET sheet of the substrate 1 using a thermal head simulator to obtain an information recording medium 1. The first information recording unit 12 using the green phosphor is printed with an image of a person as visual information, and the second information recording unit 13 using the red phosphor is printed with a barcode, did.

The results of the information recording medium 1 obtained in this way are as follows. First, there was no visible information on the surface of the base material 1, and some portions with slightly different surface properties were in a certain state. Next, when the entire surface of the base material 1 was scanned on the surface using a semiconductor laser of 950 nm (output 0.05 W), a green person image and a red barcode were confirmed in Example 1-1. . In Example 1-2, although a green person image could be confirmed, light emission of a red barcode could not be visually confirmed. In Example 1-3, light emission of any image could not be confirmed visually.

  Both the machine reading information of Example 1-2 and the information in Example 1-3 could not be visually confirmed, but as shown in the light emission intensity column of Table 1, light was emitted although it was weak. It is possible to detect through an optical filter. In this case, in particular, the state of Example 1-2 is an ideal operation in which only visual information can be confirmed during visual observation, and both images can be detected during machine reading.

  Next, a comparative example is shown. A comparative example is a structure of a prior art, and replaces the red fluorescent substance of an Example with the ultraviolet fluorescent substance which is excited by the ultraviolet-ray A (350 nm) and light-emits green. The following composition was converted into a gravure ink by the same method and applied to the same film to obtain a ribbon. Table 2 shows the coating thickness, light emission intensity, and visual confirmation results.

<Composition of ultraviolet phosphor ink>
・ Acrylic resin 18 parts by weight ・ Ultraviolet phosphor 2 parts by weight ・ Gravure solvent 80 parts by weight

From Table 2, it can be seen that the combination of the green phosphor and the ultraviolet phosphor does not allow the simultaneous emission of light even when irradiated with excitation light of 950 nm. On the contrary, in order to make the ultraviolet phosphor emit light, it is necessary to irradiate ultraviolet light having a wavelength of 350 nm. In that case, the green phosphor does not emit light, and no simultaneous light emission is recognized. Therefore, in order to read both information, it turns out that it is necessary to irradiate a 950 nm light source and a 350 nm light source.

  For example, anti-counterfeiting measures (discovery or deterrence of counterfeiting) for securities such as gift certificates or (credit) cards (especially expensive or important items requiring high security measures), authenticity Information recording with verification function by providing anti-counterfeiting measures (discovery and deterrence of forgery) for authentication (for example, application to expensive items such as brand products and high-grade products) and machine-readable information It can be used in various fields such as media.

The front view which shows one Example of the information recording medium by this invention. Sectional drawing which shows an example of operation | movement of the information recording medium by this invention Sectional drawing which shows another example of operation | movement of the information recording medium by this invention Sectional drawing which shows an example of the method of reading machine reading information among operation | movement of the information recording medium by this invention. Sectional drawing which shows an example of operation | movement of the comparative example of the information recording medium by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Information recording medium 11 ... Base material 12 ... 1st information recording part 13 ... 2nd information recording part 21 ... Excitation light 22 ... Light emission 23 of 1st information recording part ... Light emission 31 of 2nd information recording part ... Optical filter 32 ... Optical sensor λ0 ... Excitation light wavelength λ1 ... Emission wavelength λ2 of the first information recording unit ... Emission wavelength of the second information recording unit

Claims (5)

      An information recording medium in which visual information or machine-readable information is formed on a base material using an ink composition mainly composed of a phosphor, and the phosphor has two or more types having different excitation wavelengths and substantially the same excitation wavelength. An information recording medium comprising a phosphor.       The information recording medium according to claim 1, wherein the information formed by the two or more types of phosphors is information indicating different contents.       The information recording medium according to claim 1, wherein at least one of the phosphors is a phosphor that is excited by infrared rays and emits visible light.       The information according to any one of claims 1 to 3, wherein at least one of the two or more types of information formed on the substrate by the phosphor is machine-readable information that can be machine-readable. recoding media.       The machine-reading information is characterized in that light emission cannot be confirmed visually even when a light amount necessary for emitting visible image information is emitted, and the amount of light emission is detectable in a reader. The information recording medium according to claim 4.