JP2014030921A - Identification medium and identification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an identification medium which is difficult to be forged by using two kinds of phosphors and forming images respectively by utilizing characteristics of the phosphors, and provide an identification device which can safely identify the images of the identification medium.SOLUTION: An identification medium contains at least two kinds of phosphors, and includes: a first image formed of first ink containing a first phosphor which emits light when irradiated with excitation light; and a second image formed of second ink containing a second phosphor which emits light of the same wavelength as the first phosphor when irradiated with excitation light of the same wavelength as the above excitation light and has a light-emitting time different from the first phosphor.

Description

  The present invention relates to an identification medium capable of determining authenticity by identifying two or more types of light emitters having different light emission times from the difference in contrast, and an identification device for identifying the identification medium.

  For example, anti-counterfeiting media such as valuable printed matter such as securities, cards and pass tickets, certificates for authenticating individuals such as driver's licenses, passports and insurance cards, and stickers that authenticate goods as authentic are forged to third parties. In order to prevent tampering, new anti-counterfeiting techniques are always required to be incorporated, and at the same time, there is a need for an authenticity determination method capable of determining whether the product is genuine.

  In the anti-counterfeiting technology, micro characters, copy check patterns, infrared absorbing ink, fluorescent light emitting ink, or the like is used in order to enhance security. Among these technologies, fluorescent light-emitting inks are inks that are difficult to see with the naked eye under normal visible light, and that can detect marks visually or with a detector by irradiating ultraviolet rays or infrared rays. is there.

  Various proposals have been made on the fluorescent ink in order to prevent forgery and alteration. For example, an image is formed on a substrate using ink containing three types of phosphors that emit light of R (red), G (green), and B (blue), and is not visible under visible light. There has been proposed an image forming method in which R, G, and B light is emitted when irradiating and a fluorescent image appears by additive color mixing (see, for example, Patent Document 1).

  However, in recent years, simple tools such as black light for excitation are commercially available, and can be easily obtained by anyone, and it can be easily known that a fluorescent image is printed. However, there is a problem that there is a possibility that light emitters and fluorescent inks can be obtained relatively easily and may be reproduced.

JP-A-10-35089

  The problem to be solved by the present invention is to provide an identification medium that is difficult to forge by using two types of light emitters and utilizing the characteristics of the light emitters to form images, respectively. It is an object of the present invention to provide an identification device that can safely identify a device.

  An identification medium according to claim 1 of the present invention is an identification medium including at least two types of light emitters, and includes a first ink including a first light emitter that emits light when irradiated with excitation light. The first image formed in the above and the excitation light having the same wavelength as the excitation light are irradiated to emit light having the same wavelength as the first light emitter, and the light emission time is different from that of the first light emitter. And a second image formed with a second ink comprising a second light emitter having the second light emitter.

In the identification medium according to claim 2 of the present invention, the difference in the light emission lifetime τ ₁ , which is the time for emitting light by being irradiated with the excitation light of the first light emitter and the second light emitter, is 0.05 ms or more. It is characterized by that.

  An identification apparatus according to claim 3 of the present invention is an identification apparatus for identifying an identification medium according to claim 1 or claim 2, wherein one light projecting that emits excitation light of a light emitter included in the identification medium Means, one light receiving means for detecting emitted light corresponding to the irradiation of the excitation light by the light projecting means, and after stopping the irradiation of the excitation light by the light projecting means based on the output of the light receiving means And identifying means for distinguishing the first image and the second image after a certain time based on a difference in contrast.

  According to the identification medium of the first aspect of the present invention, by providing each of the images including at least two types of light emitters having the same part of the excitation wavelength region and the light emission wavelength region and having different light emission times. Discrimination becomes possible by identifying the contrast by one light projecting means and one light receiving means.

  In addition, according to the identification medium of claim 2 of the present invention, since the difference in the light emission lifetime between the two phosphors is 0.05 ms or more, a contrast can be clearly obtained, and detection by the identification device can be performed. It becomes easy.

  According to the identification device of claim 3 of the present invention, there are a light projecting unit for exciting two phosphors, and two types of light emitters after a predetermined time since the irradiation of the excitation light by the light projecting unit is stopped. By providing the light receiving means for receiving the emitted light, it is possible to obtain an effect that the image of the two light emitters can be identified by the difference in contrast by one light projecting means and one light receiving means.

The top view which shows typically the structure of the identification medium which concerns on embodiment of this invention. FIG. 2 is a longitudinal side view taken along line X-X ′ in FIG. 1. 2 is a graph showing the time and emission intensity after the irradiation of excitation light on the identification medium in FIG. 1 is stopped. The schematic diagram which shows roughly the structure of the identification device which concerns on embodiment of this invention. The figure which shows an example when the identification medium of FIG. 1 is seen with the identification device of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 schematically show the configuration of an identification medium 1 according to an embodiment of the present invention. The identification medium 1 includes a first image 21 formed of a first ink including a first light emitter that emits light when irradiated with excitation light on a base material 11, and the same wavelength as the excitation light. Formed of a second ink that includes a second light emitter that emits light having the same wavelength as the first light emitter and is irradiated with the first light emitter, and has a light emission time different from that of the first light emitter. The second image 22 is provided, and an information image 31 is printed as necessary.

  The substrate 11 is preferably a substrate that does not contain a substance having a fluorescent property. Although it is preferable that the bleaching agent used for the purpose different from the phosphor for providing the function of the present invention is not contained, it can be used even if it contains it. The substrate material to be used is selected according to each application.

  For example, when the identification medium 1 of the present invention is provided on a part of a ticket, high-quality paper is selected, but when the identification medium 1 of the present invention is provided on a part of a card, a plastic sheet such as vinyl chloride or PET is used. Is selected.

  Further, when the identification medium 1 of the present invention is provided in a part of the package, for example, coated cardboard is used, or when used for a label, tacky quality paper or coated paper is used. Or

  Furthermore, from the viewpoint of preventing re-sticking, a film that is both brittle, for example, a film obtained by forming a highly crystalline plastic material such as cellulose acetate, low-density polyethylene, polystyrene, polyphenylene sulfide, etc. from a solution film is used. . Moreover, when there is no necessity of a base material by a use, you may enable it to peel by providing a peeling layer in a base material.

  The illuminant contained in the ink that forms the first image 21 and the second image 22 is excited by the same wavelength light and further emitted by the same certain wavelength light. The wavelength of the peak of the excitation spectrum and the peak of the emission spectrum is any of ultraviolet light, visible light, and infrared light, and the near infrared region is desirable. In addition, it is most preferable that the peak of the excitation wavelength and the emission wavelength are the same because it is easy to detect light emission, but excitation may be performed with the same wavelength light even if the peak wavelength is different or has a different peak.

  A light emitter is a substance that emits energy when it absorbs energy, and is a substance that absorbs light (ultraviolet light / visible light) and emits light. The light has energy represented by E = hν (E: energy, h: Planck constant, ν: frequency). When light hits a substance, the energy of the light may be absorbed by the substance, and the substance that is in a stable energy state (ground state) due to energy absorption temporarily becomes a high energy state (excited state). Become. The material then releases energy and tries to return to a stable ground state. At this time, a phenomenon in which the energy of the difference is emitted as light instead of heat is referred to as light emission. Many materials emit light having a longer wavelength than absorbed light because some of the absorbed energy is emitted as thermal energy, but some produce light having a shorter wavelength.

  Light emission by light stimulation includes fluorescence and phosphorescence, but is sometimes referred to as fluorescence as a major conclusion, and in the present invention, it is described as a light emitter including phosphorescence and fluorescence. In fluorescence, part of the absorbed energy is released as heat and the remaining energy is released as light. On the other hand, heat is similarly released in the case of phosphorescence. At this time, intersystem crossing occurs, and the phenomenon in which light cannot be returned to the ground state immediately and continues to emit light slowly is phosphorescence. In most cases, fluorescence is emitted on the order of nanoseconds and phosphorescence is emitted on the order of microseconds to milliseconds.

  When a substance absorbs ultraviolet and visible light, an electronic transition occurs. This electron has a spin direction, and there is a rule that two electrons exist in opposite directions (Pauli's exclusion principle). In normal excitation, the spin direction remains reversed, but in the case of phosphorescence, intersystem crossing occurs, the spins are in the same direction, cannot return to the ground state as it is, and it takes time to return to the ground state. Is.

As shown in FIG. 3 showing the relationship between the time after the irradiation of the excitation light is stopped and the light emission intensity, the light emission intensity is attenuated with time after the irradiation of the excitation light is stopped. The light emission lifetimes τ ₁ of the two light emitters used in the present invention must be different, and desirably the difference between the light emission lifetimes τ ₁ of the two light emitters is 0.05 μs or more. Since these differences are required, it is desirable that at least one of the two types of light emitters of the present invention is a phosphor, or both are phosphors.

The light emission lifetime τ ₁ as used in the present invention is a time which is an average value obtained by calculating an approximate curve with a graph representing the relationship between the time after stopping the irradiation of excitation light and the light emission intensity, and integrating the approximate line. . Due to the difference in the light emission lifetime τ ₁ , the light emission intensities of the two types of light emitters are S ₁ and S ₂ at time t after the irradiation of the excitation light is stopped, and a difference appears in the light emission intensity. .

The difference in light emission lifetime τ ₁ between two or more phosphors is required to be 0.05 ms or longer, and preferably 0.1 ms or longer. In the present invention, an image at time t is identified after at least irradiation of excitation light is stopped. Since it is difficult to imitate by identifying images other than the time t together, images of a plurality of times may be identified.

As the illuminant, for example, fine particles described in Japanese Patent No. 4276864 can be used. Rare earth which is represented by the general formula (Y _1-xy , Er _x , Yb _y ) ₂ O ₃ (0.001 ≦ x ≦ 0.20, 0 <y ≦ 0.20) and is activated The elements are Er (erbium) and Yb (ytterbium). For example, two types of light emitters with different Yb concentrations can be used. In particular, the present invention is not limited to this, and other phosphors and phosphors may be used.

  The first image 21 and the second image 22 containing the phosphor are preferably offset printing, flexographic printing, gravure printing, ink jet printing, screen printing, and pad printing, but can also be formed by other printing methods. It can be formed by using a transfer machine or a laminating machine.

  It is desirable that the first image 21 and the second image 22 have at least a portion that does not overlap. It is preferable that the first image 21 and the second image 22 do not overlap. If they do not overlap, detection of the first image 21 and the second image 22, and the portion where neither the first image 21 nor the second image 22 is present can be detected with three types of contrast. In addition, in the case of overlapping, the first image 21 and the second image 22, the portion where the first image 21 and the second image 22 overlap, the portion where the first image 21 and the second image 22 are not present At least four types of contrast images can be formed. These first image 21 and second image 22 can form a code, and can also include unique identification information. For example, it is possible to create a barcode as the second image 22 and to obtain an image obtained by removing the barcode of the reverse version as the first image 21 and to detect only with this combination in the contrast image. It is also possible to put another code, not a reverse version, or a picture instead of a code.

  The information image 31 that is a pattern layer may be composed of a plurality of layers. In addition to Y (yellow), magenta (M), and C (cyan), which are used for normal printing, special color inks in which these are mixed or a special pigment is used can be used. Further, a white hiding layer for hiding the first image 21 and the second image 22 or other colored hiding layers may be used. Furthermore, a varnish layer may be provided outside the pattern layer for concealment or to improve the appearance and durability, and another optical interference effect with a decorative effect may be printed, transferred or bonded. May be provided. The printing method of the pattern layer is preferably offset printing, flexographic printing, gravure printing, ink jet printing, screen printing, pad printing, but other printing methods may also be used, and can be provided by using a transfer machine or a laminating machine. .

  FIG. 4 schematically shows the configuration of the identification device 2 according to the embodiment of the present invention. The identification device 2 identifies the first image 21 and the second image 22 on the identification medium 1 and irradiates the first image 21 and the second image 22 on the identification medium 1 with excitation light. The light projecting means 41 is provided. In the first image 21 and the second image 22 irradiated with the excitation light by the light projecting means 41, the phosphor contained in the ink emits light having a wavelength different from that of the excitation light, and the emitted light is the optical filter. It is configured to enter the light receiving means 42 through 43.

  The output of the light receiving means 42 is sent to the processing means 44. Based on the output of the light receiving means 42, the processing means 44 identifies the first image 21 and the second image 22 after a predetermined time from the stop of the irradiation of the excitation light by the light projecting means 41 by the difference in contrast.

  In order to identify the first image 21 and the second image 22 of the identification medium 1, the light projecting unit 41 forms the first ink that forms the first image 21 and the second ink that forms the second image 22. For example, an LED (light emitting diode) is desirable, but light including the excitation wavelength of the illuminant, such as a laser beam or an incandescent lamp, can also be used. . In the case where an LED is used for the light projecting means 41, it is a preferable form that a bullet-type LED is used and the bullet-type epoxy portion of the LED is a lens.

  The light projecting means 41 may emit continuous light or pulse light, but in the case of continuous light, it is necessary to block the light. The light irradiation angle is not particularly limited, but the light irradiation angle of the light projecting unit 41 that irradiates the identification medium 1 is not the same as the light receiving angle of the light receiving unit 42 that receives the light emitted from the identification medium 1. Better.

  The phosphor in the ink that forms the first image 21 and the second image 22 on the identification medium 1 is excited by the light projecting means 41 to emit light. The emitted light passes through the optical filter 43 and enters the light receiving means 42. The optical filter 43 transmits light having a wavelength to emit light and blocks disturbance light and, if necessary, light irradiated by the light projecting unit 41. A long pass filter that transmits light having a wavelength longer than an arbitrary wavelength and blocks light shorter than that is desirable, but another filter such as a band pass filter may be used.

  The light receiving means 42 is a light receiving element that receives the light emitted by the phosphor in the ink that forms the first image 21 and the second image 22 on the identification medium 1 and converts it into an electrical signal. A CMOS camera or a CCD camera is preferable. For example, in the case of a camera, since the light emitting portion becomes white, it becomes whitest when excitation light is irradiated by the light projecting means 41, and light emission becomes weak with time, so in the image turns from white to gray and disappears. The image is displayed in black.

  Therefore, the first image 21 and the second image 22 become white, and when the irradiation of the excitation light by the light projecting means 41 is stopped or blocked, the color changes from white to gray and becomes black. FIG. 5 shows an example thereof, which shows an image after time t seconds after the irradiation by the light projecting means 41 is stopped, and portions other than the first image 21 and the second image 22 appear black, The first image 21 appears gray with the light emission attenuated, and the second image 22 appears white because the light emission time is longer than that of the first image 21. The time t should be large as long as the difference in the emission intensity S between the first image 21 and the image 22B is from 0.05 ms to several seconds, and particularly preferably from 0.1 ms to several milliseconds.

  Specific examples of the present invention will be described below.

<Example 1>
First, a code such as the second image 22 is screen printed with the first ink containing the first phosphor (first light emitter) on the high-quality paper, and dried in an oven at 80 ° C., A mark including a phosphor having a thickness of 5 μm is provided, and a second ink containing a second phosphor (second light emitter) is used to form a pattern reverse to the first ink as in the first image 21. Then, screen printing was performed, and the medium was put into a dryer at 80 ° C. and dried to obtain the identification medium 1.

[First ink]
First phosphor (Y _0.89 , Yb _0.1 , Er _0.01 ) ₂ O ₃ 25 parts by weight Vinyl chloride 25 parts by weight Cyclohexanone 30 parts by weight Isophorone 20 parts by weight [second ink]
Second phosphor (Y _0.97 , Yb _0.02 , Er _0.01 ) ₂ O ₃ 25 parts by weight Vinyl acetate 25 parts by weight Cyclohexanone 30 parts by weight Isophorone 20 parts by weight The identification medium 1 obtained above is shown in FIG. Reading was performed on the identification device 2 shown in FIG. As shown in FIG. 4, the light projecting means 41 was irradiated with infrared light by an LED that emits infrared light having a central wavelength of 980 nm as an excitation wavelength. The infrared LED was installed with an inclination of 30 degrees from the vertical direction. Further, an infrared camera was installed as the light receiving means 42 in the vertical direction, and an optical filter 43 that blocked light of 850 nm or more and passed light of about 850 nm or less was held in front of the infrared camera.

<Comparative example>
In the identification device 2 of Example 1, the ink was changed to the following two types, the wavelength of the excitation light of the identification device 2 was changed to 365 nm, and the optical filter 43 was changed to a long pass filter that transmits wavelengths of 400 nm and after. The identification medium 1 was read in the same manner as in Example 1 except for the above.

[First ink]
First phosphor (Lumicol # 1000, manufactured by Nippon Fluorescent Chemical Co., Ltd.) 10 parts by weight Vinyl acetate 40 parts by weight Cyclohexanone 30 parts by weight Isophorone 20 parts by weight [second ink]
Second phosphor (Sinloicolor FZ-2002, manufactured by Sinloihi Co., Ltd.) 10 parts by weight Vinyl acetate 40 parts by weight Cyclohexanone 30 parts by weight Isophorone 20 parts by weight In Example 1 and Comparative Example, the identification medium 1 was read. It was. For Example 1, the code was displayed on the identification device 2, but for the comparative example, the screen was black and no code was displayed.

  As is apparent from the measurement results of Example 1 and the comparative example, the reading can be performed in Example 1, and the comparative example cannot be read. After irradiating the excitation light, reading the image after an appropriate time after stopping the irradiation, it is possible to differentiate by reading the image while irradiating the excitation light, it can be read with excellent anti-counterfeiting It was.

  DESCRIPTION OF SYMBOLS 1 ... Identification medium, 2 ... Identification apparatus, 11 ... Base material, 21 ... 1st image formed with the 1st ink which contains 1st light-emitting body, 22 ... It comprises 2nd light-emitting body 2nd image formed with 2nd ink, 31 ... Information image, 41 ... Light projection means, 42 ... Light receiving means, 43 ... Optical filter, 44 ... Processing means.

Claims (3)

  A first image formed of a first ink comprising a first light emitter that is an identification medium comprising at least two types of light emitters and emits light when irradiated with excitation light; Second light comprising a second light emitter that emits light having the same wavelength as the first light emitter when irradiated with excitation light having the same wavelength as the light, and has a light emission time different from that of the first light emitter. And a second image formed of the ink. 2. The identification medium according to claim _{1, wherein} a difference in light emission lifetime τ ₁ , which is a time for emitting light by being irradiated with excitation light of the first light emitter and the second light emitter, is 0.05 ms or more. . An identification device for identifying an identification medium according to claim 1 or 2,
One light projecting means for irradiating excitation light of a light emitter included in the identification medium;
One light receiving means for detecting the emitted light corresponding to the irradiation of the excitation light by the light projecting means;
Based on the output of the light receiving means, an identification means for identifying the first image and the second image after a predetermined time from the stop of the irradiation of the excitation light by the light projecting means by a difference in contrast,
An identification device comprising:

Images