Optical encoder which use a rectangular photodetector array
US4661696A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 4, 1985 |
| Grant date | Apr 28, 1987 |
| Priority date | — |
| Expiry date | Jun 4, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/34715
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An improved optical encoder is disclosed. The encoder includes a moveable scale with alternating equally dimensioned opaque and translucent regions extending generally perpendicular to the locus of scale movement; and a light source, a mask and a rectangular photodetector array having at least a pair of generally symmetrical, rectangular photodetector areas, the longitudinal dimensions of those areas being disposed relative to the regions of the scale at a predetermined acute angle of rotation. The mask defines at least two series of equally spaced apart elongated phase shifted openings aligned to be generally parallel with the regions of the scale, the mask openings being aligned at the same angle of rotation as the major lineal dimensions of the photodetector areas. The mask openings are substantially coextensive with the rectangular photodetector areas. The light source, mask and photodetector array are commonly mounted on a single axis of rotation in a rotatable stationary housing. Rotation of the housing provides a smooth bilateral electrical phase trim; and, the improved encoder uses a rectangular photodetector array of the minimum effective size.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.