Method for formation of invisible marking and method for reading of invisible marking
First Claim
1. A method for formation of invisible marking, which comprises printing information on the surface of a substrate with a marking ink containing a mixture of an indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate.
1 Assignment
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Accused Products
Abstract
Information is printed on the surface of a substrate with a marking ink containing a mixture of an indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate, to prepare an invisible marking-printed material; and infrared rays of 2-10 μm wavelength are applied onto the invisible marking-printed material to measure the infrared absorptivities of the invisible marking area and other area of said material and identify the information signified by the invisible marking.
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Citations
18 Claims
- 1. A method for formation of invisible marking, which comprises printing information on the surface of a substrate with a marking ink containing a mixture of an indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate.
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18. A marking ink containing a mixture of an indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate.
Specification