Method for reading of invisible marking
US5686725A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 6, 1995 |
| Grant date | Nov 11, 1997 |
| Priority date | — |
| Expiry date | Jun 6, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/12
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method for reading of information, which comprises printing information on a metal substrate or a substrate capable of transmitting infrared rays of 2-10 .mu.m wavelength, with a marking ink containing tin oxide, indium-tin mixed oxide or a mixture of tin oxide or indium-tin mixed oxide and at least one compound selected from the group consisting of alumina, barium sulfate, silicon dioxide and calcium carbonate, as necessary coating a clear coating or a coloring ink on at least the information-printed area of the substrate, and identifying the information by the use of a CCD camera sensitive to infrared rays of 2-10 .mu.m wavelength or an infrared detector. No noise is generated even when the reflectance of a light from the substrate surface is large, and the information can be identified (read) easily.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.