JPH07331239A - Infrared luminous fluorescent substance, fluorescent substance composition, material carrying fluorescent substance thereon, latent image mark-forming member, optical reader and optical reading system - Google Patents

Abstract

PURPOSE:To obtain an infrared luminous fluorescent substance, containing iron and erbium as optically active elements, absorbing light in a wide region of visible to near infrared rays and excitable by exposure to exciting light and capable of emitting infrared rays. CONSTITUTION:This fluorescent substance contains iron (Fe) and erbium (Er) as optically active elements and preferably further at least one selected from the group of scandium (Sc), gallium (Ga), aluminum (Al), indium (In), yttrium (Y), bismuth (Bi), cerium (Ce), gadolinium (Gd), lutetium (Lu) and lanthanum (La).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared-emitting phosphor that emits infrared light when irradiated with excitation light having a predetermined wavelength, a phosphor composition containing the phosphor, and the phosphor. The present invention relates to a supported phosphor-supported material, a latent image mark forming member formed of the phosphor composition, an optical reading device for optically reading the latent image mark, and an optical reading system.

[0002]

2. Description of the Related Art In recent years, mainly in the distribution industry, management of goods by bar codes has been actively carried out in each industry, and bar codes are printed on various prepaid cards or pass cards. This bar code is read by using the optical reading device described above, and a predetermined processing operation is performed.

Recently, credit cards, prepaid cards and the like have been used as payment methods in place of cash. There are various methods for providing anti-counterfeiting means to these cards or determining whether or not the cards are counterfeit. Proposed.

As one of them, a mark such as a bar code is printed with an ink containing a phosphor to form a latent image mark,
There has been proposed a method of irradiating the latent image mark with infrared rays to optically detect fluorescence emitted from the latent image mark.

FIG. 19 shows LiNd used as a phosphor.
Emission spectrum of P ₄ O ₁₂ (spectrum a), FIG.
21 is an emission spectrum (spectrum b) of a semiconductor laser diode having a center wavelength λp of 810 nm, and FIG. 21 is a spectrum of light received by a light receiving element. The spectrum b in FIG. 21 is the reflected light of the laser output from the semiconductor laser diode and is the same as the emission spectrum (spectrum b) in FIG. Further, a dotted line (c) in FIG. 21 is a cutoff characteristic curve of an optical filter attached near the light receiving surface of the light receiving element in order to separate the spectrum a and the spectrum b.

As described above, since the wavelengths of the emission spectrum of the phosphor (spectrum a) and the emission spectrum of the semiconductor laser diode (spectrum b) are considerably different from each other,
An optical filter having the characteristics of (c) is used. Then, while irradiating the latent image mark with the laser output from the semiconductor laser diode, the reflected light of the laser is blocked by the optical filter, and only the fluorescence emitted from the latent image mark is transmitted and received by the light receiving element, The latent image mark can be detected.

[0007]

By the way, the Nd-activated phosphor LiNdP ₄ O ₁₂ is a conventionally known material, and its production method, properties, usage method, etc. are generally known. Even if is used as a latent image mark for preventing forgery, its effect is weak.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a novel infrared-emitting phosphor, a phosphor composition containing the phosphor, a phosphor-supported material carrying the phosphor, The present invention provides a latent image mark forming member formed of the phosphor composition, an optical reading device and an optical reading system for optically detecting the latent image mark and the phosphor-supported material.

[0009]

In order to achieve the above-mentioned object, the first invention of the present invention comprises Fe and E as optically active elements.
It is characterized in that it contains r and emits infrared light when irradiated with excitation light of a predetermined wavelength.

In order to achieve the above-mentioned object, the second aspect of the present invention provides a plurality of light-emitting elements for irradiating the phosphor-supporting material according to claim 7 with two or more excitation lights having different wavelengths. A single light receiving element for receiving the fluorescence emitted from the infrared emitting phosphor, the excitation light is simultaneously emitted from the plurality of light emitting elements, and the fluorescence emitted from the infrared emitting phosphor is received by the light receiving element. It is characterized by receiving light.

In order to achieve the above-mentioned object, a third aspect of the present invention provides a plurality of light-emitting elements for irradiating the phosphor-supported material according to claim 7 with excitation light having two or more different wavelengths. And a single light receiving element for receiving the fluorescence emitted from the infrared light emitting phosphor, and sequentially irradiating the excitation light from the plurality of light emitting elements in time series to emit the fluorescence emitted from the infrared light emitting phosphor. Light is received by the light receiving element. In order to achieve the above-mentioned object, a fourth aspect of the present invention relates to a first embodiment for exciting the first infrared-emitting phosphor with respect to the infrared-emitting phosphor-carrying material according to claim 8.
Light emitting element, a first light receiving element for receiving fluorescence emitted from the first infrared emitting phosphor, a second light emitting element for exciting the second infrared emitting phosphor, and a second light emitting element for exciting the second infrared emitting phosphor. A second light receiving element for receiving the fluorescence emitted from the infrared emitting phosphor of No. 2, and is configured to judge whether or not a signal is output from each light receiving element. .

[0012]

[Function] Conventionally known Nd-activated phosphor or Nd, Y
The wavelength of the excitation light for the b-activated phosphor is the absorption wavelength of Nd (550 nm, 580 nm, 750 nm, 810 nm).
Therefore, the types of light emitting elements that can be used are also limited.

On the other hand, in the first invention, since Fe is used as the optically active element, it is possible to absorb and excite light in a wide range from visible light to near infrared light. The usable range of is expanded.

The emission wavelength of the conventionally known Nd-activated phosphor or Nd, Yb-activated phosphor is about 1000 nm.
For that reason, a Si photodiode has been used as a light receiving element.

On the other hand, in the first invention, the emission wavelength is about 1500 n due to Er used as the optically active element.
m, the emission wavelength range is different from that of the conventionally known phosphor, and therefore, the conventional Si photodiode cannot receive light and can be distinguished from the conventional phosphor, and particularly, forgery prevention, tampering prevention, etc. The effect is remarkable where such security is required.

Further, since the emission wavelength is about 1500 nm, it is possible to use various photodiodes such as Ge, InGaAs, PbS, PbSe, etc., and the usable range of the light receiving element is expanded.

In the second aspect of the invention, as described above, the phosphor having a wide light absorption region is simultaneously irradiated with a plurality of light emitting elements that emit light having different wavelengths to excite the phosphor. The intensity of the fluorescent light that is selectively emitted is increased, and the output can be increased.

Therefore, the fluorescent substance can be detected with certainty, reliability can be improved, and high-speed reading can be performed.

Further, in the third aspect of the invention, as described above, fluorescent light having a wide light absorption region is sequentially irradiated with excitation light from a plurality of light emitting elements that emit light of different wavelengths in a time series,
The fluorescence emitted from the phosphor is received by the light receiving element. Therefore, from the presence or absence of output of the light receiving element,
It is possible to judge whether or not the fluorescent substance of the present invention is a genuine substance and to improve security.

Further, in the fourth invention, the novel first infrared-emitting phosphor according to the present invention and the second infrared-emitting phosphor which emits fluorescence of a wavelength different from that of the phosphor are carried. The first light-emitting element and the first
The second infrared light emitting device and the second light emitting device and the second light receiving device are configured to judge whether or not a signal is output from each light receiving device. It is possible to judge whether or not the body is a genuine one carrying the body and the second infrared light emitting phosphor, and the security can be improved.

[0021]

Embodiments of the present invention will now be described with reference to the drawings.
1 is a plan view of an optical reading device according to an embodiment, FIG. 2 is an exploded perspective view of a main part of a reading head in the optical reading device, and FIG. 3 is a sectional view of the reading head in the XX direction of FIG. Four
FIG. 3 is a sectional view of the reading head in the YY direction of FIG.

As shown in FIG. 1, the optical reading apparatus is a printed wiring board including an apparatus main body 1, a reading head 2 mounted in the apparatus main body 1, and various elements connected to the reading head 2 to operate. It is mainly composed of 3 and 3.

As shown in the figure, a guide groove 5 into which the card 4 is inserted is formed on the upper surface of the apparatus main body 1, and the reading head 2 is attached to the inner wall surface of the guide groove 5 as desired.

A card 4 having a bar code pattern, which will be described later, is inserted in the direction of the arrow along the guide groove 5, while the bar code pattern information is optically read by the reading head 2.

As shown in FIG. 2, the reading head 2 has a head body 6 also serving as a case, a slit sheet 7 inserted into the head body 6, a sheet pressing member 8 also serving as an element holder, and It is composed of a light emitting element 9 and a light receiving element 10 held by the sheet pressing member 8 and a head carver 11 that closes the upper surface opening of the head body 6.

An opening 13 parallel to the longitudinal direction of the bar code pattern 28 formed on the card 4 is formed in the center of the lower surface of the head main body 6, and engaging steps are formed on both sides of the lower surface as shown in FIG. A section 14 is provided. Head body 6
Sheet receiving surfaces 15, 15 inclined from both sides toward the opening 13 are formed inside the sheet receiving surface 1.
A pin 16 (see FIG. 2) is provided upright in the middle of the holes 5 and 15, and locking grooves 17 (see FIG. 2) are provided at both ends of the opening 13.

As shown in FIGS. 2 and 3, flanges 18, 18 for attaching the read head 2 to the apparatus main body 1 are provided in the vicinity of the upper opening of the head main body 6 so as to project therefrom.

As shown in FIG. 2, the slit sheet 7 is a flexible sheet in which a black printing layer 20 is formed on a transparent sheet such as polyethylene terephthalate except for the slit-shaped light transmitting portion 19 (see FIG. 2). It consists of There are holes 21 in front of and behind the slit sheet 7.
Is provided in the hole 21 and the pin 16 of the head body 6 is provided.
The slit sheet 7 is positioned on the head main body 6 by inserting the respective slits, and the slit-shaped light transmitting portion 19 of the slit sheet 7 is arranged in the opening 13 of the head main body 6 as shown in FIG.

In this embodiment, the printing layer 2 is formed on the transparent sheet.
Although 0 is formed, a slit sheet in which slit-shaped grooves are formed in an opaque thin plate such as stainless steel can also be used.

As shown in FIGS. 2 and 3, the lower surface of the sheet pressing member 8 is curved along the sheet receiving surface of the head main body 6, and the lower surface of the sheet pressing member 8 and the head main body 6 are curved. The slit sheet 7 is sandwiched between the sheet receiving surface 15 and the transparent portion 19 of the slit sheet 7 is pushed into the opening 13 of the head body 6. A slit-shaped light regulating hole 22 is formed in the center of the sheet pressing member 8 and faces the light transmitting portion 19 as shown in FIG.

On both sides of the sheet pressing member 8, locking pieces 23, 23 (see FIG. 2) each having a T-shaped planar shape are provided so as to project therefrom.
The sheet pressing member 8 is mounted in the head body 6 by fitting the sheet pressing member 8 into the locking grooves 17, 17.

A holding wall 24, which is partially arcuate, is formed on the upper portion of the sheet pressing member 8, and the tip portions of the light emitting element 9 and the light receiving element 10 are inserted and held in the holding wall 24 as shown in FIG. To be done.

Four engaging claws 25 project downward around the periphery of the head cover 11, and as shown in FIG. 3, the engaging claws 25 are respectively engaged with the engaging step portions 14 of the head body 6. By assembling, the assembly of the read head 2 is completed.

As shown in FIG. 3, a leg portion 26 projects downward from the inner surface of the head cover 11, and when the head cover 11 is completely assembled as shown in FIG. The sheet pressing member 8 is pressed against the sheet receiving surface 15 side via the light receiving element 10, and the slit sheet 7 is securely fixed.

Next, the structure of the card 4 will be described with reference to FIGS. The card 4 is used as, for example, various prepaid cards or pass cards.

FIG. 5 is a plan view of the card, and FIG. 6 is an enlarged sectional view of the main part of the card.

A printed layer 29 having a latent image barcode pattern 28 is formed on the surface of the card substrate 27. The card substrate 27 is composed of, for example, a vinyl chloride sheet in which a white pigment such as titanium oxide is dispersed and held,
It has the property of reflecting visible rays and infrared rays.

On the printed layer 29, a desired bar code pattern 28 is formed by fluorescent substance fine particles and an ink whose main component is a transparent binder which holds the fine particles. The thickness T of the printed layer 29 is 0.5 to 5 from the output relation.
0 μm is suitable.

The above-mentioned phosphor is an infrared-emitting phosphor that emits infrared light when irradiated with excitation light of a predetermined wavelength, and contains iron (Fe) and erbium (Er) as optically active elements, In addition to the optically active element, scandium (Sc), gallium (Ga), aluminum (Al),
Indium (In), yttrium (Y), bismuth (Bi), cerium (Ce), gadolinium (Gd),
It contains at least one element selected from the group of lutetium (Lu) and lanthanum (La).

More specifically, an infrared-emitting phosphor having the following general formula (1): A ₃ D ₅ O ₁₂ of the general formula (1) wherein A is Y, Bi, Ce, Gd, Lu, La. And at least one element selected from the group of Er, and D includes at least one element selected from the group of Sc, Ga, Al, and In, and Fe.

Alternatively, an infrared-emitting phosphor having the following general formula (2), general formula (2) ADO ₃ wherein A is at least 1 selected from the group consisting of Y, Bi, Ce, Gd, Lu and La. Seed element and Er, D is at least one element selected from the group of Sc, Ga, Al and In, and Fe.

Alternatively, it is an infrared-emitting phosphor having the following general formula (3).

General formula (3) A ₂ D ₄ O ₁₂ wherein A is at least one element selected from the group of Y, Bi, Ce, Gd, Lu and La and Er, and D is Sc. , Ga, Al, In, at least one element selected from the group, and Fe.

The phosphors having the above general formula are used alone or in the form of a mixture.

More specifically, the following infrared emitting phosphors are used.

.. Er _0.2 Y _2.8 Fe _1.5 Al _3.5 O ₁₂ . _{Er 0.5 Y 2.5 Fe 1.5 Ga 3.5} O 12. Er _0.2 Lu _2.8 Fe _2.5 Al _3.5 O ₁₂ . Er _0.05 La _0.95 Fe _0.3 Al _0.7 O ₃ . Er _0.02 La _0.98 Fe _0.1 Ga _0.9 O ₃ Next, specific examples of these phosphors will be described.

As a raw material to be charged, a composition having a weight ratio shown in FIG. 22 was thoroughly mixed in a mortar and then baked under the conditions shown in the figure. Thereafter, hot water and 2 mol of nitric acid were used to remove unreacted materials, and each Er was removed. _0.2 Y _2.8 Fe _1.5 Al _3.5 O ₁₂ (Example 1), Er _0.5 Y _2.5 Fe _1.5 Ga _3.5 O ₁₂ (Example 2), Er _0.2 Gd _2.8 Fe _2.5 Al _2.5 O ₁₂ (Example 3), Er _0.05 La An infrared emitting phosphor of _0.95 Fe _0.3 Al _0.7 O ₃ (Example 4) and Er _0.02 La _0.98 Fe _0.1 Ga _0.9 O ₃ (Example 5) was obtained.

(ErY) obtained according to Example 1 above.
The absorption spectrum of ₃ (FeAl) ₅ O ₁₂ is shown in FIG. 7, and the emission spectrum is shown in FIG.

Fe added as an optically active element is shown in FIG.
As shown in, a wide range from visible light to near infrared light (about 4
The phosphor can be excited by a semiconductor laser or a light emitting diode that exhibits light absorption over a range of 0 to 1100 nm and emits light in this region.

The excited Fe gives energy to Er and emits light having a wavelength of about 1400 to 1670 nm.

FIG. 9 is a spectral sensitivity characteristic diagram of a germanium (Ge) photodiode, and FIG. 10 is indium (In)-.
It is a spectral sensitivity characteristic figure of a gallium (Ga) -arsenic (As) photodiode.

As shown in FIG. 8, the peak of the emission spectrum of the phosphor containing Er is at about 1540 nm, whereas the Ge photodiode shown in FIG.
The InGaAs photodiode shown in FIG.
Since it has a high sensitivity in the range of 0 to 1600 nm, it is suitable as a light receiving element of this type and has a feature that the barcode pattern can be reliably read even if the reading speed is high.

Besides, a PbS photodiode (light receiving sensitivity; about 600 to 1800 nm) and a PbSe photodiode (light receiving sensitivity; about 1000 to 4500 nm)
Can also be used.

The absorption and emission spectrum characteristics as described above can be similarly obtained in other infrared emitting phosphors containing Fe and Er as optically active elements.

The content of the fluorescent fine particles in the printed layer 29 is preferably 30 to 80% by weight. If the content is less than 30% by weight, the output from the printed layer 29 (bar code pattern 28) is weak. On the other hand, when the content exceeds 80% by weight, the printability of the print layer 29 (bar code pattern 28) deteriorates,
Printing defects may occur.

As the binder, for example, a non-solvent type such as an ultraviolet curable resin, a solvent type such as polyurethane, or a water-soluble type such as polyvinyl alcohol (PVA) can be used. It is appropriately selected depending on the material. In addition, a plasticizer, a surfactant and the like can be added if necessary.

Printing layer 29 (bar code pattern 28)
Is, for example, thermal transfer, inkjet, offset printing,
It can be formed by screen printing or gravure printing. Although not shown in FIG. 6,
A transparent protective layer is formed on the print layer 29 (bar code pattern 28).

FIG. 11 is a timing chart showing the light emission timing from the light emitting element and the output state of the light receiving element.

As shown in (a) of the figure, the light emitting element is turned on and off at time intervals (for example, 500 μsec) at which the lighting time T ₁ and the extinction time T ₂ are substantially equal to each other, and intermittently with respect to the print layer. Irradiate with excitation light. S ₁ in the figure is
The lighting signal of the light emitting element is shown.

(B), (c), and (d) of the same figure show the output state of the light receiving element when the bar code pattern is detected. The phosphor in the barcode pattern is excited by the irradiation of the light from the light emitting element, and the output increases until the light emitting element is completely turned on as shown in FIG. Even after the irradiation from the light emitting element is stopped, the light receiving element receives the afterglow emitted from the barcode pattern. Since this afterglow decreases with time, a reference value Vs is set in advance, and by comparing with this reference value Vs, a rectangular signal S ₃ is obtained after the light emitting element is turned off.

Therefore, the code information of the bar code pattern can be optically read by repeatedly turning on and off the light emitting element at every minute time.

In the method utilizing the afterglow of the fluorescent material as described above, since the light emitting element is turned off when the bar code pattern is read, there is no reflected light, and therefore the fluorescent light is obtained without using an expensive optical filter. It is possible to provide a small-sized and low-cost optical reading system capable of detecting the

FIG. 6C shows a method of detecting the afterglow of the phosphor, but it has the property of blocking the light (reflected light) of the light emitting element and passing only the light (fluorescence) emitted from the phosphor. By using the provided optical filter, it is possible to detect the light from the phosphor when the light emitting element is on. FIG. 7D shows the output state of the receiving element at that time, and the rectangular signal S
You get ₄ .

FIG. 12 shows an example in which the infrared light emitting phosphor of the present invention is printed on securities.

It is possible to print only the phosphor according to the present invention on the securities to prove that the securities are authentic, but in this embodiment, a plurality of kinds of phosphors are used to further enhance security. It is used.

That is, as shown in FIG.
The latent image marks 31a, 31b, 31c are individually formed at predetermined positions of the above, and the latent image marks 31a to 31c individually contain phosphors having emission spectra different from each other.

Light-emitting elements 9a, 9b, 9c for irradiating each latent image mark 31a-31c with excitation light having a predetermined wavelength, and each latent image mark 31a-31c.
Light receiving elements 10a, 10 for receiving fluorescence emitted from the
b and 10c are arranged in pairs.

Examples of the above-mentioned phosphors having different emission spectra include one or more kinds of phosphors selected from the following groups.

(First Phosphor Group) An infrared-emitting phosphor having the following general formulas (1) to (3).

General formula (1) A ₃ D ₅ O ₁₂ General formula (2) ADO ₃ General formula (3) A ₂ D ₄ O ₁₂ where A is a group of Y, Bi, Ce, Gd, Lu and La. And at least one element selected from the group Er and D. At least one element selected from the group of Sc, Ga, Al, and In, and Fe.

More specifically, Er _0.2 Y _2.8 Fe _1.5 Al _3.5 O ₁₂ . _{Er 0.5 Y 2.5 Fe 1.5 Ga 3.5} O 12. Er _0.2 Lu _2.8 Fe _2.5 Al _3.5 O ₁₂ . Er _0.05 La _0.95 Fe _0.3 Al _0.7 O ₃ . The emission spectrum of the phosphor composed of Er _0.02 La _0.98 Fe _0.1 Ga _0.9 O ₃ (ErY) ₃ (FeAl) ₅ O ₁₂ is shown in FIG.

(Second Phosphor Group) An infrared emitting phosphor having the following general formula (4).

General formula (4) EG _1-XY Nd _X Yb _Y P ₄ O ₁₂ wherein E is at least one element selected from the group of Li, Na, K, Rb and Cs, and G is S
c, Y, La, Ce, Gd, Lu, Ga, In, Bi,
It consists of at least one element selected from the group of Sb. X is a numerical value in the range of 0.05 to 1.0, Y is 0
The numerical value in the range of 0.95 and X + Y are 1.0 or less.

More specifically, LiNdP ₄ O ₁₂ . LiNd _0.9 Yb _0.10 P ₄ O ₁₂ . LiY _0.05 Nd _0.85 Yb _0.10 P ₄ O ₁₂ . The emission spectrum of the phosphor of LiBi _0.10 Nd _0.8 Yb _0.10 P ₄ O ₁₂ LiNdP ₄ O ₁₂ is shown in FIG.

(Third Phosphor Group) An infrared-emitting phosphor having the following general formula (5).

Formula (5) JEr _M Yb _Q L ₁ -MQ P _R O _T However, in the formula, J is at least one element selected from the group of Li, Na, K, Rb, and Cs, and L is Y,
It is composed of at least one element selected from the group consisting of La, Ce, Gd, Lu, In and Bi.

M is a numerical value in the range of 0.01 to 0.99 Q is a numerical value in the range of 0.01 to 0.99 R is a numerical value in the range of 1 to 5 T is a numerical value in the range of 4 to 14

More specifically, KYb _0.9 Er _0.1 P ₄ O
_{12 and the} like, and their emission spectra are shown in FIG.

Therefore, the above-mentioned Er _0.2 Y _2.8 Fe _1.5 Al _3.5 O ₁₂ and LiN are added to the latent image marks 31a to 31c.
When the phosphors of dP ₄ O ₁₂ and KYb _0.9 Er _0.1 P ₄ O ₁₂ are used, the respective fluorescence is emitted by the light receiving element 10a,
The securities 30 are judged to be genuine by receiving the light at 10b and 10c. If any one of the light receiving elements 10a, 10b, 10c does not receive light, it is determined that the security 30 is not authentic.

Although the example of FIG. 12 shows the case where the phosphors having different emission spectra are individually used, the latent image mark 31 may be formed by mixing the phosphors having different emission spectra as shown in FIG. It is possible.

In this case, the latent image mark 31 is irradiated with excitation light from the light emitting elements 9a, 9b, 9c, and the fluorescent light emitted from the latent image mark 31 having different emission spectra is received by the light receiving elements 10a, 10b, 10c, respectively. Received light. An optical filter is attached to the front surface of each of the light receiving elements 10a, 10b, and 10c, which transmits a light component to be received and blocks light of other wavelengths.

FIG. 15 is a diagram for explaining a reading system that can obtain a high output by utilizing the fact that the phosphor according to the present invention has a wide absorption spectrum range.

That is, as shown in the figure, a latent image mark 31 containing the phosphor according to the present invention is formed on the surface of an object to be detected 32 such as a card, for which, for example, 60
A first light emitting element 9d for irradiating 0 nm excitation light λ1,
Second light emitting element 9e for irradiating excitation light λ2 of 950 nm
And are arranged. As shown in FIG. 7, the phosphor according to the present invention has absorption peaks in the vicinity of about 600 nm and about 950 nm, and therefore the light emitting elements 9d and 9e that output light of that wavelength are selected. .

When the latent image marks 31 are simultaneously irradiated with excitation light of different wavelengths from the light emitting elements 9d and 9e, the amount of fluorescence emitted from the light emission elements 9d and 9e is naturally larger than that of the case where the excitation light having one kind of wavelength is irradiated, and therefore, the received light is received. The output of the element 10 becomes high. The fact that high output is obtained in this way means
It is suitable for a high-speed reading system for latent image marks.

FIG. 16 is a diagram for explaining a reading system with high security utilizing the fact that the phosphor has a wide absorption spectrum range according to the present invention.

That is, as shown in the figure, the detected object 32 having the latent image mark 31 containing the phosphor according to the present invention.
Are transported in the direction of the arrow by the transporting means 33, which is, for example, a conveyor.

On the upstream side in the carrying direction, for example, 680 nm
The first light emitting element 9d for irradiating the excitation light λ1 and the first light receiving element 10d are arranged as a pair. Further, on the downstream side thereof, a second light emitting element 9e for irradiating the excitation light λ2 of 950 nm, for example, and a second light receiving element 10e are arranged in pairs.

The object 32 to be detected is the first light emitting element 9
d-first light receiving element 10d and second light emitting element 9e
-By passing under the second light receiving element 10e,
Since the outputs are obtained from the first light receiving element 10d and the second light receiving element 10e, respectively, the detected object 32 is determined to be a genuine object. If any one of the light receiving elements 10 does not output, the detected object 32 is determined to be a counterfeit product that does not use the phosphor according to the present invention.

In this example, the detected body 32 passes under the first light emitting element 9d-the first light receiving element 10d and the second light emitting element 9e-the second light receiving element 10e. However, the following modifications are also possible.

That is, the first light emitting element 9d for emitting the excitation light λ1 and the second light emitting element 9 for emitting the excitation light λ2.
e and one light receiving element 10 that receives the fluorescence emitted from the latent image mark 31 are arranged at one location.

First, the second light emitting element 9e is turned off, the first light emitting element 9d is turned on, the fluorescence from the latent image mark 31 is received by the light receiving element 10, and then the first light emitting element 9d is turned on. If the second light emitting element 9e is turned off and the light receiving element 10 can similarly receive light, the detected object 32 is determined to be a genuine object.

Although FIG. 15 and FIG. 16 show an example in which two light emitting elements 9 are used, respectively, it is also possible to use three or more light emitting elements that emit light in the light absorption region of the phosphor. is there.

In each of the above-described embodiments, an example in which a latent image mark 31 containing a phosphor is carried by printing or the like on an object to be detected such as a card is shown, but FIGS. 17 and 18 show other examples of the phosphor. It is a figure for demonstrating a carrying method.

FIG. 17 shows an example in which phosphor particles 35 are carried between fibers 34 constituting a non-woven fabric or a woven fabric. For example, when phosphor particles 35 are added when filtering paper for bills, securities, betting tickets, certificates, etc., a non-woven fabric as shown in FIG. 17 is obtained. When illegally copying securities, horse betting tickets, certificates, etc. with a color copying machine, if the fluorescent particles 35 are optically detected in the color copying machine and the copying operation is automatically prohibited, illegal copying will occur before it happens. Can be prevented.

As described above, since the phosphor according to the present invention has a wide light absorption region, it can be excited by the light from the light source of an ordinary color copying machine. It can be used as a light emitting element.

FIG. 18 shows an example in which phosphor particles 35 are dispersed and held in a synthetic resin sheet 36. Since the phosphor particles 35 are almost transparent, a transparent synthetic resin sheet 36
Even if added inside, the transparency hardly decreases. The detection target to which the synthetic resin sheet 36 containing the phosphor particles 35 is attached can be discriminated from other counterfeit products as a genuine product.

The optical reading system of the present invention has the following uses and features in addition to the above.

(1). Factory automation (F
A) Related management When assembling automobiles, that is, by vehicle type, export destination country, manufacturing date, manufacturing lot, etc., can be managed without losing appearance by using latent image marks.

(2). Even if a black object such as a tire or a transparent object such as glass or synthetic resin, which cannot be read by a conventional reflective barcode, is marked, the mark can be read.

(3). Since the latent image mark can be read even if characters or designs are printed on the latent image mark, it is possible to superimpose information retention and effectively use a narrow space such as a price tag or a product tag of a product.

(4). For the same reason as the above (1) and (3), it is effective to be used for products such as cosmetics and medicines where design is important, or various cosmetic boxes and packages that require a high-class feeling.

(5). The latent image marks can be read even in environments where conventional reflective barcodes cannot be used because they are contaminated with oil and dust at factories and sites.

(6). For the same reason as in (1) and (3) above, the manufacturer's control as a hidden code on the delivery slip to the customer (usually, the delivery slip contains only the information required by the customer in the form and format specified by the customer) Information can be given.

(7). Information can be inserted into a card-like object as a hidden code and used as a game card (bar code game).

(8). For the same reason as the above (1) and (3), if it is used for book management, book management, drawing management, etc., the design will not be damaged.

(9). Since it is extremely difficult to forge, alter, and falsify, it can be applied to entry / exit control, attendance control, key cards such as hotels.

(10). Forgery, alteration, and tampering of student ID cards and ID cards can be prevented, and downsizing and space saving can be achieved.

(11). Forgery, alteration, and tampering of stamp cards and point cards can be prevented, and downsizing and space saving can be achieved.

(12). It can be introduced into a pachinko prize exchange system to prevent forgery, alteration, and tampering.

[0110]

EFFECTS OF THE INVENTION Nd-activated phosphor or N known in the prior art
The wavelength of the excitation light for the phosphors activated by d and Yb is the absorption wavelength of Nd (550 nm, 580 nm, 750 nm, 810 nm).
nm), the type of light emitting element that can be used is also limited.

On the other hand, in the first invention, since Fe is used as the optically active element, it is possible to absorb and excite light in a wide range from visible light to near infrared light. The usable range of is expanded.

The emission wavelength of the conventionally known Nd-activated phosphor or Nd, Yb-activated phosphor is about 1000 nm.
For that reason, a Si photodiode has been used as a light receiving element.

On the other hand, in the first invention, the emission wavelength is about 1500 n due to Er used as the optically active element.
m, the emission wavelength range is different from that of the conventionally known phosphor, and therefore, the conventional Si photodiode cannot receive light and can be distinguished from the conventional phosphor, and particularly, for counterfeit prevention and tampering prevention. The effect is remarkable where such security is required.

Further, since the emission wavelength is about 1500 nm, it is possible to use various photodiodes such as Ge, InGaAs, PbS and PbSe, and the usable range of the light receiving element is expanded.

In the second aspect of the invention, as described above, the phosphor having a wide light absorption region is simultaneously irradiated with a plurality of light emitting elements which emit light of different wavelengths to excite the phosphor. The amount of fluorescent light that is emitted is increased, and the output can be increased.

Therefore, the fluorescent substance can be reliably detected, the reliability can be improved, and high-speed reading can be performed.

Further, in the third invention, as described above, fluorescent light having a wide light absorption region is sequentially irradiated with excitation light in a time series from a plurality of light emitting elements which emit light with different wavelengths,
The fluorescence emitted from the phosphor is received by the light receiving element. Therefore, from the presence or absence of output of the light receiving element,
It is possible to judge whether or not the fluorescent substance of the present invention is a genuine substance and to improve security.

Furthermore, in the fourth invention, the novel first infrared-emitting phosphor according to the present invention and the second infrared-emitting phosphor that emits fluorescence of a wavelength different from that of the phosphor are carried. The first light-emitting element and the first
The second infrared light emitting device and the second light emitting device and the second light receiving device are configured to judge whether or not a signal is output from each light receiving device. It is possible to determine whether or not the body is a genuine one carrying the body and the second infrared-emitting phosphor, and it is possible to improve security.

[Brief description of drawings]

FIG. 1 is a plan view of an optical reading device according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part of a reading head in the optical reading device.

3 is a sectional view of the read head in the XX direction of FIG.

FIG. 4 is a sectional view of the reading head in the YY direction of FIG.

FIG. 5 is a plan view of a card according to an embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of the card.

FIG. 7 shows (ErY) ₃ (FeA) according to an example of the present invention.
1) is an absorption spectrum diagram of a ₅ O ₁₂ phosphor.

FIG. 8 is an emission spectrum diagram of the (ErY) ₃ (FeAl) ₅ O ₁₂ phosphor.

FIG. 9 is a spectral sensitivity characteristic diagram of a Ge photodiode.

FIG. 10 is a spectral sensitivity characteristic diagram of an InGaAs photodiode.

FIG. 11 is a timing chart showing a light emission timing from the light emitting element and an output state of the light receiving element.

FIG. 12 is an explanatory diagram showing an example in which the phosphor of the present invention is printed on securities.

FIG. 13 is an emission spectrum diagram of a KYb _0.9 Er _0.1 P ₄ O ₁₂ phosphor.

FIG. 14 is an explanatory diagram showing another example in which the phosphor of the present invention is printed on securities.

FIG. 15 is a diagram for explaining a reading system of the present invention.

FIG. 16 is a diagram for explaining another reading system of the present invention.

FIG. 17 is an enlarged cross-sectional view showing another example of the phosphor-supporting material of the present invention.

FIG. 18 is an enlarged cross-sectional view showing still another example of the phosphor-supporting material of the present invention.

FIG. 19 is an emission spectrum diagram of a LiNdP ₄ O ₁₂ phosphor.

FIG. 20 is an emission spectrum diagram of a semiconductor laser diode.

FIG. 21 is a spectrum diagram of light received by a light receiving element when the LiNdP ₄ O ₁₂ phosphor is irradiated with light having the characteristics of FIG. 20.

FIG. 22 is a diagram showing a weight ratio of charged raw materials and firing conditions in each example of the present invention.

[Explanation of symbols]

 2 read head 4 card 9, 9a, 9b, 9c light emitting element 9d first light emitting element 9e second light emitting element 10, 10a, 10b, 10c light receiving element 10d first light receiving element 10e second light receiving element 27 card substrate 28 Bar Code Pattern 29 Printing Layer 30 Securities 31a, 31b, 13c Latent Image Mark 32 Detected Object 34 Fiber 35 Phosphor Particles 36 Synthetic Resin Sheet

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C09K 11/78 CPN 11/80 CPM CPN G06K 7/12 C 0829-5B (72) Inventor Toshio Oshima Ibaraki, Osaka Prefecture 1-88 Ichira-Tora, Hitachi Maxell Co., Ltd.

Claims (17)

[Claims] 1. An infrared-emitting phosphor, which contains iron (Fe) and erbium (Er) as optically active elements and emits infrared light when irradiated with excitation light of a predetermined wavelength. 2. In addition to the optically active element according to claim 1, scandium (Sc), gallium (Ga), aluminum (Al), indium (In), yttrium (Y), bismuth (Bi), cerium ( Ce), gadolinium (Gd), lutetium (Lu), lanthanum (L
An infrared-emitting phosphor containing at least one element selected from the group a). 3. An infrared-emitting phosphor having the following general formula, which emits infrared light when irradiated with excitation light having a predetermined wavelength. General formula A ₃ D ₅ O ₁₂ where A is at least one element selected from the group of Y, Bi, Ce, Gd, Lu and La and Er, and D is Sc, Ga, Al, In Fe and at least one element selected from the group. 4. An infrared-emitting phosphor, which has the following general formula and emits infrared light when irradiated with excitation light having a predetermined wavelength. General formula ADO ₃ where A is at least one element selected from the group of Y, Bi, Ce, Gd, Lu and La and Er, and D is selected from the group of Sc, Ga, Al and In. And Fe. 5. An infrared-emitting phosphor, which has the following general formula and emits infrared light when irradiated with excitation light having a predetermined wavelength. General formula A ₂ D ₄ O ₁₂ where A is at least one element selected from the group of Y, Bi, Ce, Gd, Lu and La and Er, and D is Sc, Ga, Al, In Fe and at least one element selected from the group. 6. A phosphor composition comprising fine particles of the infrared-emitting phosphor according to claim 1 and a dispersant for dispersing and holding the fine particles. 7. A phosphor-supporting material carrying the infrared-emitting phosphor according to any one of claims 1 to 5. 8. A first infrared-emitting phosphor according to claim 1 and a second infrared-emitting phosphor that emits fluorescence of a wavelength different from that of the phosphor. A phosphor-carrying material characterized by the above. 9. The phosphor-supported material according to claim 7, wherein the carrier is paper. 10. A latent image mark forming member, wherein a latent image mark containing the infrared light emitting phosphor according to claim 1 is formed. 11. A plurality of light-emitting elements that irradiate the phosphor-supported material according to claim 7 with excitation light having two or more different wavelengths, and receive fluorescence emitted from the infrared-emitting phosphor. An optical reading device, comprising: 12. A first light-emitting element for exciting the first infrared-emitting phosphor, and the first infrared-emitting phosphor for the phosphor-supporting material according to claim 8. A first light receiving element for receiving fluorescence emitted from the second infrared emitting phosphor, a second light emitting element for exciting the second infrared emitting fluorescent material, and a second light receiving element for receiving the fluorescent light emitted from the second infrared emitting fluorescent material. An optical reading device comprising two light receiving elements. 13. The method according to claim 11 or 12,
The light receiving element is a Ge photodiode or InGaA.
An optical reader characterized by being an s photodiode. 14. A plurality of light-emitting elements that irradiate the phosphor-supported material according to claim 7 with excitation light having two or more different wavelengths, and receive fluorescence emitted from the infrared-emitting phosphor. An optical reading system comprising: a single light-receiving element for irradiating excitation light from the plurality of light-emitting elements at the same time, and the fluorescence emitted from the infrared-emitting phosphor is received by the light-receiving element. 15. A plurality of light-emitting elements that irradiate the phosphor-supported material according to claim 7 with excitation light having two or more different wavelengths, and receive fluorescence emitted from the infrared-emitting phosphor. One optical receiving element for irradiating excitation light from the plurality of light emitting elements sequentially in time series, and the fluorescence emitted from the infrared light emitting phosphor is received by the light receiving element. system. 16. A first light emitting element for exciting the first infrared light emitting phosphor, and a first infrared light thereof, with respect to the infrared light emitting phosphor-supporting material according to claim 8. Description: A first light receiving element for receiving the fluorescence emitted from the light emitting phosphor, a second light emitting element for exciting the second infrared light emitting phosphor, and a fluorescence emitted from the second infrared light emitting phosphor. Second to receive light
And an optical reading system configured to judge whether or not a signal is output from each light receiving element. 17. The optical reading system according to claim 14, wherein the light receiving element is a Ge photodiode or an InGaAs photodiode.