Method for formation of invisible marking and method for reading of invisible marking
US5547501A · kind A · utility
155Cited by
4References
18Claims
0Family size
Assignees
Inventors
Key dates
| Filing date | May 5, 1995 |
| Grant date | Aug 20, 1996 |
| Priority date | — |
| Expiry date | May 5, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/06009
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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 .mu.m 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.