Reticle bar code and method and apparatus for reading same
US4567361A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 23, 1983 |
| Grant date | Jan 28, 1986 |
| Priority date | — |
| Expiry date | May 23, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/0002
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In the reticle bar code scheme disclosed herein, the peculiar characteristics and requirements of a microlithographic reticle are utilized in a bar code scheme which provides multiple levels of error checking while permitting an extensive repertoire of reticle identifying characters. In reading the bar code, the reticle is moved passed a photoelectric sensor and, by counting a clock signal, the width of each bar is measured. A synchronization character at the start of the data character string provides a nominal bar width value and each character comprises three bars of each polarity, the bars being integral multiples of the nominal value with the width of the character being ten times the nominal value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.