Apparatus for detecting proper positioning of objects in a holder
US5466945A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 23, 1994 |
| Grant date | Nov 14, 1995 |
| Priority date | — |
| Expiry date | Mar 23, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S414/135
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The positions of objects in a holder, such as a cassette containing semiconductor wafers, are determined by a system that projects a pair of coplanar light beams through the cassette from one side. A reflector on the opposite side reflects both light beams back though the cassette and onto separate photodetectors on the one side. A computer analyzes signals from the photodetectors as the cassette is moved through the light beams. As the cassette moves the light beams are interrupted by the wafers. The relative widths and timing of pulses in the signals indicate the location of wafers in the cassette and whether a wafer is misaligned.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.