Infrared phosphor and material having latent images and optical reading system using said phosphor
First Claim
Patent Images
1. An infrared phosphor having nonacicularly-shaped particles that are less than or equal to 4 μ
- m in size, the phosphor being stimulated to phosphoresce by infrared light, the infrared phosphor comprising a phosphate compound represented by the following formula;
space="preserve" listing-type="equation">Ln.sub.x B.sub.1-x PO.sub.4wherein;
B represents at least one element selected from the group consisting of Y, La, Gd, Bi, Ce, Lu, In, Pr and Tb;
Ln represents at least one element selected from the group consisting of Nd;
Yb and Er; and
x is a numerical value of 0.01 to 0.99.
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Abstract
The invention provides a phosphor excited by infrared rays to emit infrared rays which has a nonacicular particle shape and a particle size of 4 μm or smaller after being synthesized. The phosphor preferably comprises an oxoacid salt-containing compound including at least one element selected from the group consisting of Nd, Yb and Er. The invention further provides a material having a latent image pattern comprising said phosphor and an optical reading system which use the material having a latent image pattern.
61 Citations
11 Claims
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1. An infrared phosphor having nonacicularly-shaped particles that are less than or equal to 4 μ
- m in size, the phosphor being stimulated to phosphoresce by infrared light, the infrared phosphor comprising a phosphate compound represented by the following formula;
space="preserve" listing-type="equation">Ln.sub.x B.sub.1-x PO.sub.4wherein;
B represents at least one element selected from the group consisting of Y, La, Gd, Bi, Ce, Lu, In, Pr and Tb;
Ln represents at least one element selected from the group consisting of Nd;
Yb and Er; and
x is a numerical value of 0.01 to 0.99. - View Dependent Claims (2, 3)
- m in size, the phosphor being stimulated to phosphoresce by infrared light, the infrared phosphor comprising a phosphate compound represented by the following formula;
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4. A material having a latent image comprising:
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a substrate; and a print layer on the substrate; the print layer including; an infrared phosphor having nonacicularly-shaped particles that are less than or equal to 4 μ
m in size, the phosphor being stimulated to phosphoresce by infrared light; anda binder; wherein the infrared phosphor comprises a phosphate compound represented by the following formula;
space="preserve" listing-type="equation">Ln.sub.x B.sub.1-x PO.sub.4and wherein;
B represents at least one element selected from the group consisting of Y, La, Gd, Bi, Ce, Lu, In, Pr and Tb;
Ln represents at least one element selected from the group consisting of Nd, Yb and Er; and
x is a numerical value of 0.01 to 0.99. - View Dependent Claims (5, 6, 7, 8)
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9. An optical reading system for detecting phosphorescence of a marking substance on an object, the system comprising:
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an infrared light emitter; a marking substance on the object, the marking substance including an infrared phosphor having nonacicularly-shaped particles that are less than or equal to 4 μ
m in size, the phosphor being stimulated to phosphoresce by the infrared light from the light emitter; anda light detector, the light detector operating after the light emitter turns off so as to detect the phosphorescence from the phosphor; wherein the infrared phosphor of the marking substance on the object comprises a phosphated compound represented by the following formula;
space="preserve" listing-type="equation">Ln.sub.x B.sub.1-x PO.sub.4and wherein;
B represents at least one element selected from the group consisting of Y, La, Gd, Bi;
Ce;
Lu, In, Pr and Tb;
Ln represent at least one element selected from the group consisting of Nd, Yb and Er; and
x is a numerical value of 0.01 to 0.99. - View Dependent Claims (10, 11)
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Specification