Two-dimensional optical encoder with three gratings in each dimension
US5204524A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 1992 |
| Grant date | Apr 20, 1993 |
| Priority date | — |
| Expiry date | Mar 9, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A first grating is formed on a main scale, and a second and third gratings on an index scale. The first grating generally assumes a cruciform shape, and consists of a grating having grating lines arranged in the X-direction and another grating having grating lines arranged in the Y-direction. The second grating is formed in a square central area of the index scale, and consists of two gratings having grating lines arranged in the X-direction and divided at the center and another two gratings having grating lines arranged in the Y-direction and divided at the center. The third grating consists of four gratings having grating lines arranged in the X-direction with different phases and another four gratings having grating lines arranged in the Y-direction with different phases. A light-emitting element and eight photodetectors that are arranged corresponding to the respective gratings of the third grating are fixed to a movable member on which the index scale is attached. Light emitted from the light-emitting element passes though the second grating, reflected by the first grating, passes through the third grating, and finally detected by the photodetectors. Alternatively, the first g…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.