Diffraction type optical encoder with improved detection signal insensitivity to optical grating gap variations
US4983825A · kind A · utility
10Cited by
4References
4Claims
0Family size
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Key dates
| Filing date | Mar 8, 1990 |
| Grant date | Jan 8, 1991 |
| Priority date | — |
| Expiry date | Mar 8, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a reflection type encoder having a main scale and an index scale with first and second gratings, respectively, and using a diffusing light source, diffused rays from a point light source are focused by a condensing lens to produce a secondary point light source positioned on a plane defined by the second gratings of the index scale. With this arrangement, a collimator lens can be dispensed with, so that the encoder can be rendered compact in size. Furthermore, the respective elements can be easily supported and positioned.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.