Diffraction-type optical encoder with improved detection signal insensitivity to optical grating gap variations
US4985623A · kind A · utility
8Cited by
3References
3Claims
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Key dates
| Filing date | Mar 8, 1990 |
| Grant date | Jan 15, 1991 |
| Priority date | — |
| Expiry date | Mar 8, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In an optical encoder using a collimated lighting system, an index scale is inclined toward a main scale by a predetermined value. With this arrangement, a component of variation in the detection signal due to variations in the grating gap can be offset or integrated to be removed from a geometric image of the first grating in the detection signal, whereby the dependence of an S/N ratio of the detection signal on the grating gap can be avoided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.