JPH10289287A - Method for detecting information attached to detected body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to detect information which is written on the detected body and can not be recognized with natural light or an ordinary light source by adding information by coating the detected body with an invisible substance, irradiating the invisible substance with ultraviolet rays, and detecting the information from excitation light generated by the irradiation with the ultraviolet rays. SOLUTION: A paper card or plastic card is used as the detected substance. A fluorescent substance which emits excitation light having specific peak wavelength is an invisible substance which can not be seen with the human eye with visible light and emits the excitation light having specific wavelength by being irradiated with ultraviolet rays. The peak wavelength of the excitation light at this time is detected to know that the information is formed by applying the specific fluorescent substance. The light source only needs to emit the ultraviolet rays, and a mercury lamp, an ultraviolet-ray fluorescent lamp, an ultraviolet-ray diode, or ultraviolet-ray laser diode is usable. Consequently, the precision of a decision on the card is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating information formed by coating an invisible substance on a detection object with ultraviolet light, and detecting information attached to the detection object, which detects the information from excitation light generated. Regarding the method of detecting.

[0002]

2. Description of the Related Art Conventionally, ink which is invisible to the naked eye under natural light or a normal light source, but which emits fluorescence by irradiation of a specific ultraviolet ray, is already known as an invisible ink. It is known that multiple information can be transmitted by, for example, performing multiple printing on a business card and detecting a character that has generated fluorescence by scanning a scanner as specific information (Japanese Patent Application Laid-Open No. H10-163873). 63-109093).

[0003] As a typical example of a system for optically reading information attached to an object to be detected, a bar code system is widely used. This bar code system detects information by irradiating a bar code provided on an object with visible light or infrared light, and reading a reflected light pattern with a reading device.

In the conventional barcode system, the shape of the barcode itself is easily recognized by human eyes. Therefore, the thickness of the bar and the bar interval can be easily copied.
While this is an advantage, it also has disadvantages in the following respects.

[0005] The first drawback is a problem when it is necessary to transmit confidential information such as security or personal privacy because a counterfeit product can be easily created.

A second drawback is that, in order to accurately transmit information by a bar code, it is necessary to print a large bar thickness and length, but the shape of the bar code is seemingly meaningless. Because it is only recognized as an inorganic pattern,
If a barcode is attached to the detected object, the appearance may be impaired depending on the product.

A third disadvantage is that a space for attaching a bar code is required, so that a space for a character or a picture to be printed on the surface of a card or a product which is an object to be detected may be narrowed. .

In view of the above situation, the invisible information is reliably transmitted, or the invisible information is hidden in the visible information on the specific article, and the specific article is identified based on the specific wavelength of the excitation light detected when ultraviolet light is irradiated. It has been awaited to use it for authenticity determination, and to realize means for detecting and transmitting invisible information on an object to be detected, for example, replacing a conventional barcode.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for detecting natural light written on an object to be detected or information which cannot be recognized under a normal light source by irradiation of ultraviolet rays.

[0010]

According to the present invention, there is provided a method for detecting information attached to an object to be detected, comprising the steps of applying an invisible substance to the object and applying information thereto, and applying an ultraviolet ray to the invisible substance. And a step of detecting the information from excitation light generated by the irradiation of the ultraviolet light.

[0011]

Embodiments of the present invention will be described below.

As an object to be detected in the embodiment of the present invention, a paper card or a plastic card is used. Fluorescent substances that generate excitation light having a specific peak wavelength when irradiated with ultraviolet light are, for example, the following substances.

[0013] ZnS: C having a peak wavelength of 530 nm, respectively.
u, 544 nm Y ₂ SiO ₅ : Ce, Tb, 611 nm Y ₂ O ₃ : Eu, 619 nm YVO ₄ : Eu, 625 nm
(Sr, Mg, Ba) ₃ (PO ₄ ): Sn ₂ or 6
For example, 3.5 MgO.5 MgF ₂ .GeO ₂ : Mn of 57 nm is used. These are merely examples, and other fluorescent substances may of course be used.

The fluorescent substance is an invisible substance that is invisible to human eyes under visible light, and is irradiated with ultraviolet rays to generate excitation light having a specific wavelength. If the peak wavelength of the excitation light at that time is detected, it is understood that a specific fluorescent substance is applied and information is formed.

The light source only needs to generate ultraviolet light, and may be a mercury lamp, an ultraviolet fluorescent lamp, an ultraviolet light emitting diode, or an ultraviolet laser diode. In particular, when an ultraviolet light emitting diode or an ultraviolet laser diode using a GaN-based material is used as a light source, the light source itself can be reduced in size, and power consumption of the light source can be reduced.
Advantages such as long life can be obtained.

A double heterostructure ultraviolet light emitting diode having an active layer of AlGaN is used as an ultraviolet irradiation device.
A phototransistor that detects light emission from a fluorescent substance,
When an information reading terminal is configured by combining with an LSI for processing a detected signal, the driving voltage of the terminal body is set to 9
V or less.

For this reason, the battery can be driven by a dry battery, and the entire terminal can be housed in a housing of, for example, 30 mm × 10 mm × 120 mm, so that a handy type information reading terminal can be obtained.

Although the fluorescent substance is an invisible substance that is invisible to the human eye under visible light, it is concretely described that excitation light of a specific wavelength is generated by irradiation with ultraviolet rays and can be detected as information. Confirmed.

In the first example, a pattern was printed on a paper card by mixing Y ₂ O ₃ : Eu as a fluorescent substance into ink.
The same pattern was printed on another paper card with an ink containing no fluorescent substance, and both were irradiated with ultraviolet light in a dark box protected from external light.

As a result, it was confirmed that the pattern printed with the ink containing the fluorescent substance appeared red.

In the second example, both were irradiated with ultraviolet light under natural light or a normal light source in the first example. Excitation light having a strong peak wavelength of 611 nm was detected only from a pattern printed by mixing Y ₂ O ₃ : Eu as a fluorescent substance in the ink.

In the third example, a bar code was printed on a plastic card as a fluorescent substance by mixing Y ₂ SiO ₅ : Ce, Tb powder with polyvinyl alcohol, and dried. On top of this, a fine pattern of color printing was performed with normal ink so as to cover the entire surface of the barcode. As a result, the presence of the printed barcode made of a fluorescent substance became invisible.

The plastic card was irradiated with ultraviolet light, and the code was read by a bar code reader equipped with a band pass filter that transmits light of a wavelength of 544 nm. As a result, the bar code which was invisible to human eyes could be read accurately. did it.

In the fourth example, photographs were printed by color printing on each of a large number of plastic cards. At the time of color printing, only a specific card was mixed with the fluorescent substance YVO ₄ : Eu in only the red color of the ink.

When each of the plastic cards was irradiated with ultraviolet light, only the card having the red ink portion mixed with the fluorescent substance YVO ₄ : Eu appeared red and could be visually distinguished.

In a fifth example, when printing a photograph by color printing on each of a large number of plastic cards, a specific portion where a red dot of ink is printed only in a specific card when performing color printing. Only the fluorescent substance YVO ₄ : E
The ink mixed with u was used.

As a result, although it could not be distinguished visually, only the red dot portion of the ink appeared red by irradiation with ultraviolet rays. When a specific pattern was drawn with, for example, a character or a picture using the dots of the ink mixed with the fluorescent substance, these could be easily discriminated.

In a sixth example, each card is irradiated with ultraviolet light under natural light or a normal light source in the fifth example. It was detected that excitation light having a peak wavelength of 619 nm was emitted at a certain intensity or higher only from dots printed by mixing Y ₂ O ₃ : Eu as a fluorescent substance in the ink. From this, the card mixed with the fluorescent substance could be easily identified.

In this case, if the position of the dot is specified, the card can be determined only by confirming whether the excitation light from the specific position is light of a specific wavelength.

In a seventh example, a paper card has 3Sr (PO ₄ ) ₂ .CaCl ₂ : Eu ²⁺ as three kinds of fluorescent substances and Y
_A pattern was printed by blending ₂ SiO ₅ .Ce, Tb with Y ₂ O ₃ : Eu and mixing it with ink. When this printed pattern was irradiated with ultraviolet rays, emission spectra having peak wavelengths of 453 nm, 544 nm and 611 nm unique to the mixed phosphor were obtained.

Since such an emission spectrum is determined by the type and blending ratio of the phosphor to be blended, a predetermined emission spectrum is compared with an emission spectrum measured for detection of a new paper card. Thus, it was easy to determine whether the paper card was genuine.

In the eighth example, when a large number of plastic cards are produced, only a specific card is used as a fluorescent material YVO ₄ : Eu ₄ having a peak wavelength of 619 nm in the plastic material.
Was mixed. The other cards were mixed with a powder of a non-fluorescent substance so that the finished color was the same.

Although it looks the same to the human eye, a special card containing the fluorescent substance YVO ₄ : Eu can be easily distinguished from the card having a peak wavelength of 619 nm when both are irradiated with ultraviolet rays. Was.

In any of the first to eighth examples, different fluorescent substances are applied or mixed into a plurality of specific portions on the object to be detected, and it is known in advance when ultraviolet rays are irradiated. If it is detected whether or not excitation light of a specific wavelength is generated from a location, the accuracy of card determination can be further increased.

When irradiating the paper or the plastic card with ultraviolet rays as described above,
The surfaces on which the fluorescent substance is detected are not necessarily the same. That is, ultraviolet light can be irradiated from the front surface coated with the fluorescent substance and detected on the back surface, or conversely, ultraviolet light can be irradiated from the back surface and detected on the front surface.

The above-described embodiment has been described mainly with reference to the detection of information based on a bar code. However, the present invention is not limited to this, and is invisible to the naked eye under natural light or a normal light source. Since the information applied to the detection target can be detected, it can be applied to the determination of authenticity of bills, securities, and bills. Furthermore, the present invention can also be applied to authenticity determination, such as a credit card, an ID card, and an identification card, which becomes a problem when counterfeited.

[0037]

According to the method for detecting information attached to a detected object according to the present invention, the information attached to the detected object can be transmitted without being noticed by human eyes, so that security and personal privacy can be improved. Secret information that is involved can be transmitted safely and easily without being known to humans.

Further, by changing the kind and composition of the fluorescent substance, the application position, and the like in combination, it is possible to incorporate a wide variety of information, and therefore, it is effective to make it difficult to produce an imitation product.

Further, the information provided on the detected object is less conspicuous as compared with the conventional bar code, so that the appearance is not spoiled.

Further, conventionally, a space for attaching a bar code is required. However, characters or pictorial figures to be printed on the surface of a product can be freely attached without being restricted by a space on the object to be detected. . Thus, the same function as the barcode information can be performed instead of the barcode.

Alternatively, the invisible information is hidden in the visible information on the specific article, and can be used for determining the authenticity of the specific article from the specific wavelength of the excitation light detected when irradiating ultraviolet rays.

Claims (8)

[Claims] A step of applying information by applying an invisible substance to an object to be detected; a step of irradiating the invisible substance with ultraviolet rays; and detecting the information from excitation light generated by the irradiation of the ultraviolet rays. And detecting information attached to the object. 2. The object according to claim 1, wherein the information formed by applying an invisible substance on the object forms a pattern having a specific regularity. How to detect information 3. The information formed by applying an invisible substance on an object to be detected is formed by applying a plurality of types of fluorescent substances to a plurality of locations on the object to be detected. A method for detecting information attached to a detected object according to claim 1. 4. The apparatus according to claim 1, wherein the invisible substance generates excitation light having a specific wavelength when irradiated with ultraviolet light, and detects the information by detecting a specific wavelength of the excitation light. A method for detecting information given to an object to be detected according to 1. 5. The method according to claim 1, wherein the invisible substance is obtained by mixing a plurality of types of invisible substances. 6. The step of partially applying an invisible substance to a specific portion of visible information on an object to be detected, and detecting the information, comprises: 2. The method according to claim 1, further comprising the step of determining the authenticity of the visible information by detecting a specific wavelength of excitation light generated from the substance. 7. The method according to claim 1, wherein the step of irradiating the ultraviolet rays includes irradiating the ultraviolet rays with an ultraviolet light source made of a light emitting diode (LED) or a laser diode (LD) made of a GaN-based material. A method for detecting the information attached to the object to be detected. 8. A step of applying an invisible substance on a detection object in a shape corresponding to the shape of a barcode to give barcode information, and irradiating the invisible substance serving as the barcode information with ultraviolet rays. Detecting the barcode information from excitation light generated by irradiation with the ultraviolet light.