JP2007277281A - Mixed light-emitting body, light-emitting ink, light-emitting printed matter, light-emitting material-applied article and method for distinguishing authenticity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mixture of light-emitting materials, light-emitting ink, light-emitting printed matter and a light-emitting material-coated article improving a security level by a characteristic change in the color of emitted light, and a method for distinguishing authenticity. <P>SOLUTION: This mixture of light-emitting materials is prepared by mixing at least 2 light-emitting materials having different color of the emitted lights and times for reaching the saturation of light intensity, and light-emitting ink is prepared by dispersing the light-emitting mixture with ink vehicle. By using the ink, light-emitting printed matter by applying it on a substrate material or at least a part of the inner surface of the substrate material is produced. The method for distinguishing the authenticity is provided by arranging the light-emitting printed matter at an investigation means, irradiating ultraviolet light to the light-emitting printed matter from an ultraviolet light-irradiation part, photo-electrically converting the color of the emitted light of reflecting light from the light-emitting material of the light-emitting printed matter by the irradiation of the ultraviolet light, by a photo sensor and detecting the waveform of the behavior of the light-emitting material until reaching to the saturated intensity of the emitted light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, by mixing at least two ultraviolet-excited visible light emitters having different emission colors from the excitation time until the emission intensity reaches saturation after irradiation with ultraviolet rays, the emission color is continuous according to the ultraviolet irradiation time. The present invention relates to a luminescent material mixture having excellent authenticity that changes with time, a luminescent ink obtained by mixing the luminescent material mixture in an ink vehicle, a luminescent printed material, a luminescent material coated product, and a method for determining authenticity.

  For printed matter that requires a certain level of security such as banknotes, securities, and postal tickets, an element that serves as a standard for distinguishing genuine products from counterfeit products, so-called authenticity discrimination, in order to distinguish counterfeiting and tampering by third parties. The addition of elements is essential.

  As an example of the authenticity determination element to be given, for example, a clearance applied to a bank note can be cited. This clearance allows the user to easily determine the authenticity of the banknote simply by holding it over visible light without the need for an authentication tool.

  On the other hand, as another example, there is a special authenticity determination element that is arranged on a design or background in a printed material with a configuration that is not observable with visible light, or that can be observed with visible light without causing a sense of incongruity. This authenticity determination element can be confirmed only when a special authentication tool is used, and is characterized in that it is difficult for a forger to identify its presence.

  One substance constituting the authenticity determination element that requires this special authentication tool is a light emitter. Here, the light emitter includes a phosphor, a phosphor and a phosphorescent material. There are no limit to the types of light emitters. However, if the materials composing the light emitters are different, all of the characteristics such as excitation wavelength, light emission wavelength, and afterglow intensity do not completely match each other. Utilizing this, the printed matter printed with the illuminant is irradiated with a specific excitation wavelength, and the emission color is confirmed by a sensory test, or the emission spectrum in the specific wavelength range or the afterglow by mechanical inspection. A technique for determining the authenticity of a security printed matter by detecting the intensity or the like and determining the authenticity of the light emitter itself has been generally used.

  Among the illuminants, ultraviolet-excited visible illuminants emit light in the visible region by irradiating light in the ultraviolet region with the excitation wavelength, and use simple authentication tools such as black light and germicidal lamps. The illuminant can be excited and the emitted light can be perceived by the human eye.

  Originally, UV-excited visible illuminants are also illuminants on the premise that authenticity is determined by strict mechanical inspection. It is used for security printed matter such as gift certificates, and at ticket cash exchanges and sales outlets, these security printed materials that are brought in are irradiated with ultraviolet rays using a black light and checked for authenticity by visual inspection. It is often used as one of the means.

  As described above, the UV-excited visible illuminant is recognized as an extremely simple illuminant, and has been used as an authenticity determination element in many security products so far. It was based on the premise that it can only be obtained.

  However, in recent years, many types of special UV-excited visible light emitters, which have been difficult for ordinary people to obtain, have been sold at general merchandise stores and are close to the light emitters used for genuine products. It is becoming easier to obtain light emitters having

  Thus, when a counterfeit product is manufactured by obtaining a light emitter with characteristics similar to those used for genuine products, the intensity and wavelength are strictly controlled in an environment where ambient light is blocked. Irradiation with ultraviolet light excites the illuminant and measures its emission spectrum and emission intensity to compare it with the authentic value, so the irradiation wavelength and intensity are ambiguous in the environment where ambient light is inserted. There is a problem that the possibility of erroneous determination is high in a method of performing authenticity determination by irradiating ultraviolet rays with a simple authentication tool such as a black light or a germicidal lamp and visually grasping only the emitted color.

  Based on the above, the method of using UV-excited visible light emitters as one of the authenticity determination elements of security prints is distributed even if the manufacturer intends to determine authenticity by strict mechanical inspection. Considering that there is a possibility of authenticity being determined by visual inspection during the process, there is a problem that the security level is becoming lower overall now that a wide variety of light emitters are available to the general public. It was.

  In order to deal with this problem, special ultraviolet-excited visible light emitters are being used. Typical examples of inks that are mixed with these special UV-excited visible light emitters include dichroic fluorescent inks and color shift inks. The dichroic fluorescent ink (see, for example, Patent Document 1) and the color shift ink (see, for example, Patent Document 2) are both inks in which two or more kinds of UV-excited visible light emitters are mixed in one ink vehicle. Thus, the color of light emitted when irradiated with ultraviolet rays is changed.

  Dichroic fluorescent ink is a mixture of phosphors with different ultraviolet excitation characteristics and emission colors. In many cases, dichroic fluorescent inks have fluorescent pigments that have excitation characteristics that are strongly excited by shortwave ultraviolet light and excitation characteristics that are strongly excited by ultraviolet longwaves. When mixed with a combination of fluorescent pigments and irradiated with short-wave ultraviolet light (having a central wavelength of 254 nm) and long-wave ultraviolet light (having a central wavelength of 365 nm), the emission color changes even though it is a single ink. Is.

  Specifically, using two authentication tools, a light 1 for irradiating short wave ultraviolet light and a light 2 for irradiating long wave ultraviolet light, the emission color of ink at each wavelength can be used as an authenticity determination element, It is considered that the security level is high even when compared with the conventional ultraviolet-excited visible illuminant, which could only determine authenticity with a single luminescent color. Further, considering that this dichroic fluorescent light emitter is not generally sold at present, it is less likely to be used for counterfeiting than a general ultraviolet ray excited visible light emitter.

  Further, the color shift ink is an ink whose luminescent color changes even when irradiated with ultraviolet rays in a single wavelength region, and this utilizes the difference in the afterglow time of the illuminant. For example, when a phosphor with little afterglow time and a phosphorescent material with a long afterglow time are mixed, the emission color of the phosphor becomes the main color while irradiating ultraviolet rays, and the ultraviolet ray irradiation ends. From this moment, the emission color (afterglow color) of the phosphor is the main color. When the emission color of the phosphor and the emission color of the phosphor are different, the emission color of the ink changes depending on the presence or absence of ultraviolet irradiation.

  Similar to the dichroic fluorescent ink, this color shift ink is considered to have a higher security level than the conventional ultraviolet-excited visible luminescent material that could only determine authenticity with a single luminescent color. Since this color shift ink is not generally sold, it is less likely to be used for counterfeiting than a general UV-excited visible light emitter.

  As described above, since UV-excited visible light emitters are becoming difficult to maintain their security with simple light emission, a light emitter with special characteristics that cannot be reproduced by counterfeiters is required. In addition, it is considered desirable that the characteristics can be easily grasped visually by color change.

JP-A-10-251570 JP 2005-67043 A

  As described above, the UV-excited visible illuminant is mainly required to specialize the emission color because of its ease of authentication, but the authenticity of the above-described dichroic fluorescent ink and color shift ink is also determined. Problems may arise in the authentication tool and its authentication environment.

  In order to confirm the difference in emission color in a plurality of wavelength ranges, which is a remarkable characteristic of the dichroic fluorescent ink of Patent Document 1, a UV lamp capable of irradiating at least two different wavelengths of ultraviolet rays is used. It is necessary, and authenticity determination with any one authentication tool such as a black light or a germicidal lamp is impossible. In many cases, short-wave ultraviolet rays, which are one of the certified wavelengths of dichroic fluorescent inks, are harmful to the human body and require careful handling.

  Regarding the color shift ink of Patent Document 2, unlike a dichroic phosphor, a single authentication tool is sufficient as in the past, and in most cases, the authentication wavelength is a long wave ultraviolet ray irradiated by a conventionally used black light. Almost no problem. However, in order to visually confirm the afterglow emitted from the color shift ink, an environment that can block ambient light that becomes a disturbance is required. This is a problem caused by the fact that the afterglow intensity due to stored light is extremely weak compared to the emission intensity due to fluorescence, and this problem is unavoidable. Therefore, it is difficult to visually confirm this color change in an environment illuminated with a fluorescent lamp, and an environment that can substantially block light other than ultraviolet light emitted by black light, or a special light equipped with black light. There was a problem that a dark box became essential.

  Further, in order to authenticate in a dark box, it is necessary to always have or hold the dark box, so it is not suitable for instantaneous determination.

  The present invention has been made in order to solve the above-described problems of the prior art, and it is possible to improve the security level by changing the characteristic emission color. The phosphor mixture, the luminescent ink, the luminescent printed matter, and the luminescent coated product that can be discriminated using both of these are true and the luminescent printed matter and the luminescent coated product can be easily discriminated visually or by a machine. An object is to provide a false discrimination method.

  The luminescent material mixture of the present invention is a mixture in which at least two luminescent materials having different luminescence intensity from irradiation of ultraviolet light to saturation are mixed, and the mixture is irradiated with ultraviolet light. The luminescent color changes as time elapses from the start.

  At least two light emitters of the light emitter mixture of the present invention are composed of a light emitter having a short time until the light emission intensity reaches saturation after irradiation with ultraviolet light and a light emitter having a long time until the light emission intensity reaches saturation. The light emission color of the light emitter with a short saturated light emission time from the beginning of light emission continues to emit light at a constant intensity, and the light emitter with a long saturation light emission time gradually increases in light emission intensity until reaching the saturated light emission intensity, The mixed emission color of the at least two light emitters continuously transitions until at least two light emitters reach the saturation light emission intensity.

  The luminescent ink of the present invention is obtained by dispersing a luminescent material mixture in an ink vehicle.

  The luminescent printed material of the present invention is characterized in that the luminescent material mixture is applied to at least a part of the substrate or the inner surface of the substrate.

  The phosphor-coated product of the present invention is characterized in that the phosphor mixture is applied to at least a part of the substrate or the inner surface of the substrate.

  The authenticity determination method using the luminescent printed material or the luminescent material coated material of the present invention is characterized by capturing a change in luminescent color according to the irradiation time of ultraviolet rays.

  The authenticity determination method using the luminescent printed material or the luminescent material coated material of the present invention includes arranging the luminescent printed material in an inspection unit, irradiating the luminescent printed material with ultraviolet rays from an ultraviolet irradiation unit, and The light emission color of reflected light from the light emitting body of the light emitting printed matter is photoelectrically converted by an optical sensor, and authenticity determination is performed by electrically detecting the behavior of the light emission color change until the saturation light emission intensity of the light emitting body is reached. It is characterized by that.

  According to the present invention, a change in emission color occurs only with a single ultraviolet irradiation light source, and the emission color change is gradually emitted by mixing the emission colors of at least two light emitters from the start of ultraviolet irradiation to the time of ultraviolet irradiation. A phosphor mixture having the characteristics that the color change and the emission luminance are increased can be obtained, and a luminescent ink, a luminescent print, a luminescent coating, and an authenticity determination method are provided.

  Below, the luminous body mixture, luminous ink, luminous printed material, luminous body coating material, and authenticity discrimination method by embodiment of this invention are demonstrated using drawing.

  Here, the light emitter mixture is a light emitter made according to the present invention, and was prepared by mixing two different light emitters. In addition, as the two light emitters, light emitters having a large change in emission color were selected. Although the case of two different light emitters is described in this embodiment, it goes without saying that the number of light emitters may be three or more.

  The light emitter has a maximum value at which the light emission intensity does not increase any more for a certain amount of ultraviolet irradiation light (hereinafter, this maximum value is referred to as a saturated light emission intensity). In the case of many illuminants, the saturation luminescence intensity is reached almost instantaneously when irradiated with a certain intensity of ultraviolet light. However, a specific illuminant gradually emits light after irradiating with a certain intensity of ultraviolet light. Some have characteristics that require time from the start of ultraviolet irradiation until the saturated emission intensity is reached (hereinafter, the time from the start of ultraviolet irradiation until the saturation emission intensity is reached is referred to as saturated emission time).

  The light emitter 1 with a short saturated light emission time is approximately zero seconds, and conversely, the long light emitter 2 reaches 1 second. For example, when the light emitter 1 with a saturation light emission time of approximately zero seconds and the light emitter 2 with a saturation light emission time of 1 second are mixed and dispersed uniformly, the saturation is from the start of UV irradiation until the irradiation time of 1 second. The light emission color of the light emitter 1 having a short light emission time is a main color, and when the irradiation time is 1 second or longer, the light emission color of the light emitter 1 having a short saturated light emission time and the light emission color of the light emitter 2 having a long saturation light emission time are mixed colors. It becomes.

  When these two light emitters having different light emission colors (light emission color of the light emitter 1 having a short saturated light emission time and light emission color of the light emitter 2 having a long saturation light emission time) are selected, the saturation light emission time is long. Until the illuminant 2 reaches the saturated emission intensity, the luminescent color of the illuminant 1 having a short saturated emission time immediately after UV irradiation is mainly used, but as the illuminant 2 having a long saturated emission time gradually emits light, The luminescent color of the illuminant 1 having a short luminescence time causes a color change accompanied by a special increase in luminescence intensity in which the hue continuously transitions until the luminescent color reaches a mixed color of the two illuminants. Is possible.

  It goes without saying that the greater the difference in the saturated light emission time, the easier it is to visually confirm the change in emission color and the higher the authenticity discrimination. In order to visually grasp the change in emission color, the difference in the saturated emission time is desirably 0.1 seconds or more. If the time is less than 0.1 seconds, there are differences among individuals in the authentication of the color change, and it is difficult for all people to make a true / false determination visually.

FIG. 1 shows a selection result of a light emitter that can maximize the change in the light emission color visually.
Combining R-type (red), G-type (green) and B-type (blue) illuminants with a short saturation emission time and a long saturation emission time, respectively. Thus, the luminescent color immediately after UV irradiation, the intermediate mixed color until both light emitters reach the saturation light emission intensity, and the mixed color when both light emitters reach the saturated light emission intensity are visually observed and evaluated.

  As a result, in the combination of R system (red system), G system (green system) and B system (blue system) illuminant, the luminescent color change feels maximum visually, and the intermediate mixed luminescent color and mixed color The combination with vivid color was the combination of R and G. However, it goes without saying that the present invention is not limited to this combination of R and G phosphors.

  As the light emitter 2 having a long saturated light emission time, which is one of the two light emitters, which is a constituent requirement according to the present embodiment, a phosphorescent material having a relatively long afterglow has the characteristics described in this embodiment. In many cases, the illuminant generally called a phosphorescent body is the illuminant 2 with a long saturated emission time, and other illuminants are generally phosphors or phosphors. The light emitter referred to is a light emitter 1 with a short saturated light emission time. However, some phosphors have a relatively long saturated emission time. In this case, a combination in which the difference in the saturation emission time between the light emitter 1 and the light emitter 2 is 0.1 seconds or more is, for example, a combination of a phosphor and a phosphor, or a combination of a phosphor and a phosphor. However, it is possible to constitute the phosphor mixture of the present invention.

  Appropriate mixing ratios of the respective light emitters that effectively cause a change in emission color can be calculated mechanically in advance. This is a rough indication that the integrated values of the light emission waveforms shown in the spectral spectra after the lapse of the saturated light emission time of the light emitter 1 and the light emitter 2 are approximately the same value.

(Example)
As an example in the above embodiment, the light emission color of the two light emitters is selected from a combination of R and G light emitters to produce a light emitter mixture, a light emitting ink, and a light emitting printed matter.

  Of the two illuminants, the R-based illuminant has an emission peak of 657 nm in red with the highest wavelength in the visible region 1 (vendor: Toshiba product name: SPD-116S), and the G-based illuminant has an emission peak. The phosphor 2 having a central wavelength of 516 nm (sales manufacturer: Nemoto Special Chemicals product name: DM224) was selected.

FIG. 2 shows the relationship between the saturated light emission time and the saturated light emission intensity of the light emitters 1 and 2.
The R-based light emitter 1 is excited by being irradiated with long-wave ultraviolet light, emits light at a first wavelength (657 nm), and has a saturated light emission time of approximately zero seconds. On the other hand, the G-based illuminant 2 is excited by irradiation with long-wave ultraviolet light, emits light at the second wavelength (516 nm), and has a saturation light emission time of about 1 second.

  In this embodiment, the inorganic luminescent pigment is used for the luminescent material 1 and the luminescent material 2, but there is no problem even if an organic luminescent pigment is used.

  After selecting two light emitters that satisfy the configuration requirements of the present embodiment as described above, each mixing ratio was examined in order to determine the mixing ratio at which the change in the emission color can be felt to the maximum visually. .

  The total weight of the two light emitters 1 and 2 used in this example was set to a constant value, and the mixing weight ratio of the two light emitters was adjusted in consideration of the balance of the emission color. In mixing the pigments, the mixture was carefully mixed using an agate mortar until the resulting mixture had a uniform light emission, and a phosphor mixture was obtained with the pigment uniformly dispersed. When this dispersion state is not uniform, it goes without saying that the change in the emission color of the phosphor mixture becomes the color of each of the phosphors from the start of ultraviolet irradiation, and no sharp change in the emission color occurs.

A five-level phosphor mixture in which the blending ratio of the phosphor 1 and the phosphor 2 is changed is prepared, and the phosphor mixture is irradiated with long-wave ultraviolet rays using an ultraviolet irradiation means, and a change in emission color is visually observed. The optimum blending ratio was derived on the basis of the level of change in the luminescent color.
As an ultraviolet irradiation means, an ultraviolet irradiation lamp (center wavelength: 366 nm sales manufacturer: Funakoshi Pharmaceutical Co., Ltd., product name: UVL-56) that emits ultraviolet rays in accordance with general black light was used.

  FIG. 3 shows the blending ratio of the illuminant 1 and the illuminant 2 in level 1 to level 5 of the illuminant mixture, and the visual evaluation results with respect to the change in emission color visually observed when irradiated with long wave ultraviolet rays.

  As a result of visual observation, it was confirmed that what was produced at a blending ratio of level 4 (DM224: SPD116S = 1: 5) produced the best change in emission color. In addition, the emission spectrum of the phosphor mixture of each level mechanically detected by a spectrophotometer (Hitachi, Ltd., product name: F-4500 spectrofluorometer) in a state where both the phosphors reach the saturated emission intensity is As shown in FIG. The emission spectrum of the light emitter 2 at each level appears at 450 to 600 nm, and the emission spectrum of the light emitter 1 appears at a portion of 600 to 700 nm. The integrated values of the waveforms shown in the spectrum after the saturation light emission time of the light emitter 1 and the light emitter 2 at level 4 were almost the same.

  When ultraviolet rays were irradiated to level 4, red, which is the emission color of the illuminant 1 immediately after irradiation, orange, which is an intermediate mixed color of the illuminant 1 and the illuminant 2, within 1 second from immediately after irradiation, and the irradiation elapsed time In 1 second or more, yellow, which is a mixed color of the light emitter 1 and the light emitter 2, was confirmed.

  In addition, although not the main effect of the present example, green afterglow, which is the single afterglow color of the light-emitting body 2 after the end of ultraviolet irradiation, could be confirmed as an effect accompanying the present example. From the above, the light emitting material mixture according to the present example was set at level 4 which had the highest color change effect visually.

  Next, a vehicle was selected to make the phosphor mixture into an ink, a luminescent ink was prepared, and the luminescent ink obtained was printed by a generally known printing method to produce a luminescent print. Authenticity discrimination is performed by visual or machine discrimination on the luminescent printed matter.

  An ink vehicle was selected to ink the phosphor mixture.

  Ink vehicles used in printing methods such as gravure printing, offset printing, and screen printing are all made of an organic material, and thus have the property of absorbing ultraviolet rays. It is desirable to avoid ink vehicles that have the property of absorbing ultraviolet light in particular.

  In this embodiment, the purpose of the present invention is to clearly show the change in emission color when irradiated with long wave ultraviolet rays using a commercially available black light. Decided to avoid. Further, since it is assumed that the change in the emission color is visually confirmed, it is assumed that the emission can be kept strong. For this reason, screen printing that can provide a thick ink film is selected, and an ultraviolet drying type medium (sales manufacturer: Nagase Screen Printing Laboratory product name: A-Z) used in screen printing is used. It was.

The phosphor mixture was inked at the following blending ratio. The pigment content is 30%. Using a high-speed disperser (sales manufacturer: Tokushu Kika Kogyo Co., Ltd., product name: Homodisper), the ink was made by stirring for 5 minutes at 3000 rpm, and this ink was irradiated with long-wave ultraviolet rays. The change of the luminescent color similar to the luminescent material mixture was confirmed. This was used as the luminescent ink of this example.
Luminescent substance mixture 30 parts Medium 70 parts Antifoaming agent 1 part (extra)

  Screen printing is performed using a screen printing machine (sales manufacturer: Mino Corporation, product name: desktop printing stand WHT3) using the light-emitting ink as a base material with non-fluorescent gravure printing coated paper to emit light. A printed material was obtained.

  When the effect was confirmed by irradiating the obtained luminescent printed material with ultraviolet rays, it was confirmed that the luminescent color change was almost the same as that of the luminescent mixture.

  Next, a method for determining authenticity using the light emitter mixture and the light-emitting printed matter obtained in the examples will be described with respect to visual observation and mechanical inspection.

First of all, it is not only to visually check how the emission color changes according to the UV irradiation time, but also to use a UV blocking substance to more easily observe the effect of the emission color change. explain.
In this embodiment, as a true / false discrimination method, it is assumed that a long-wave ultraviolet ray emitted from a commercially available black light is irradiated to a light emitter, and a change in light emission color of the light emitter is easily determined visually. is doing.

  After covering a part of the printed image of the luminescent printed material with an ultraviolet blocking substance such as a human hand or paper, irradiate the entire printed image with ultraviolet rays from above the ultraviolet blocking substance, and after the saturated emission time has elapsed, the entire printed image If the UV blocking substance is removed while the UV ray is still irradiated, the printed image part covered with the UV blocking substance begins to emit red light, while the printed image not covered with the UV blocking substance emits yellow light. is doing. This is because the part covered with the UV blocking substance and the part not covered with the UV blocking substance produce a part where the luminescent material having a long saturated emission time is not excited and a part where it is excited, and is partially shielded. This appears as a difference in emission color when the entire surface is irradiated with ultraviolet rays.

  In this way, by using a simple ultraviolet blocking substance, the effect of changing the emission color according to the irradiation time of ultraviolet rays can be easily visually observed as a color change in an adjacent state in the same printed matter. It becomes possible to determine the authenticity very easily.

  Next, an example of performing authenticity determination by machine determination will be described with reference to the drawings.

  FIG. 5 shows an example of a simple inspection apparatus. It is an inspection apparatus provided with a UV irradiation LED 2 as an excitation light source in a complete dark box 1 and an optical sensor 5 for photoelectrically converting light emitted from a light emitter.

  A light emitter mixture 8 to be measured is placed in the dark box 1, and a low pass filter 3 (transmitting only light having a wavelength of 390 nm or less) is disposed on the ultraviolet light emitting LED 2 with respect to the light emitter mixture 8. . The UV-irradiated LED irradiates the phosphor mixture with UV light at a duty of 50% by the pulse oscillator 4. Light emitted from the luminescent material mixture excited by ultraviolet rays was captured and electrically converted by the photoelectric conversion sensor 5, and the luminescence behavior until the saturated luminescence intensity of the luminescent material mixture was reached was detected by the oscilloscope 7 via the amplifier 6.

  FIG. 6 shows waveforms of detection results obtained by detecting with a oscilloscope the light emission behavior until reaching the saturated light emission intensity of the phosphor mixture and conventional phosphors and phosphors measured with the inspection device.

  From FIG. 6, it can be seen that the luminous body mixture obtained in this example and the light emission behavior of the conventional phosphor and phosphorescent substance are clearly different in the figure. When a conventional general phosphor is excited by ultraviolet rays, a light emission waveform rises vertically (a), a general phosphor accumulates logarithmically with respect to a saturated light emission intensity (b), whereas a phosphor mixture is Since the phosphor emits light, the initial light emission waveform rises vertically, and then the light emission intensity gradually increases logarithmically until the saturation light emission intensity is reached (c). As described above, the phosphor mixture can mechanically detect the emission waveform and can easily determine the authenticity.

  As detailed above, the emission color changes only with a single ultraviolet irradiation light source such as black light or germicidal lamp, which was impossible with dichroic fluorescent ink, and the change in the emission color is the same as the conventional color. It is not caused by afterglow like shift ink, but it is caused by the change of the saturated emission intensity of multiple light emitters from the start of ultraviolet irradiation to the time of ultraviolet irradiation, so the emission intensity during the change in emission color is also Even if ambient light is present in the authentication environment, it is possible to visually confirm the change in the luminescent color without putting it in a dark box or the like and inspecting it each time. Further, since it is possible to mechanically detect a change in light emission intensity immediately after the ultraviolet irradiation until a predetermined time elapses, it goes without saying that it functions more as a mechanical authenticity determination element. Yes.

  In this example, the luminescent printed material was formed using luminescent ink, but generally, a luminescent fiber having a luminescent material mixture fixed to the fiber was manufactured using a known fluorescent fiber manufacturing method and mixed into the substrate. In addition, it is easy to construct a base material of a luminescent printed matter by making a luminescent paper in which a luminescent material mixture is directly mixed with a paper base material, and it goes without saying that it is within the scope of the present invention.

It is a figure which shows the combination of the two light-emitting body luminescent color in this invention, the change of luminescent color, and a visual evaluation result. It is a figure which shows the relationship between the saturated light emission time of two light-emitting bodies by an Example, and saturated light emission intensity. It is a figure which shows the mixture ratio of the light-emitting body by an Example, the change of luminescent color, and the visual evaluation result. The mixing | blending ratio and emission spectrum of the light-emitting body by an Example are shown. It is a figure which shows the simple test | inspection apparatus by an Example. It is the figure which showed the light emission behavior measured with the simple test | inspection apparatus by an Example with an oscilloscope.

Explanation of symbols

1 Dark box 2 UV irradiation LED
3 Low-pass filter 4 Pulse oscillator 5 Photoelectric conversion sensor 6 Amplifier 7 Display device 8 Object to be measured

Claims (7)

A mixture in which at least two light emitters having different light emission colors and different times from the irradiation of ultraviolet light until the light emission intensity reaches saturation are mixed,
The phosphor mixture is characterized in that the emission color changes with the passage of time from the start of ultraviolet irradiation. The at least two light emitters are composed of a light emitter having a short time until the light emission intensity reaches saturation after irradiation with ultraviolet light and a light emitter having a long time until the light emission intensity reaches saturation. The light emission color of the light emitter having a short light emission time continues to emit light at a constant intensity, and the light emitter having a long saturation light emission time gradually increases in light emission intensity until reaching the saturation light emission intensity, so that the at least two light emitters The phosphor mixture according to claim 1, wherein the mixed emission color of the at least two phosphors continuously transitions until a saturated emission intensity is reached. A luminescent ink, wherein the phosphor mixture according to claim 1 or 2 is dispersed in an ink vehicle. A light-emitting printed matter, wherein the phosphor mixture according to claim 1 or 2 is applied to at least a part of a substrate or an inner surface of the substrate. A phosphor coating product, wherein the phosphor mixture according to claim 1 or 2 is applied to at least a part of a substrate or an inner surface of the substrate. A true / false discrimination method using the luminescent printed matter or the phosphor coated product according to claim 4, wherein the true / false discrimination method captures a change in emission color according to an irradiation time of ultraviolet rays. . A authenticity determination method using the luminescent printed matter according to claim 4 or 5, or a luminescent material coated product,
Placing the light-emitting printed matter on the inspection means;
Irradiate the light-emitting printed matter with ultraviolet rays from an ultraviolet irradiation unit,
The light emission color of the reflected light from the illuminant of the luminescent printed matter is photoelectrically converted by an optical sensor with respect to the ultraviolet irradiation,
A true / false determination method, wherein true / false determination is performed by electrically detecting a behavior of a change in emission color until the saturated emission intensity of the light emitter is reached.

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