Optical encoders using transmitted and reflected light detection having complementary output
US5065013A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 19, 1990 |
| Grant date | Nov 12, 1991 |
| Priority date | — |
| Expiry date | Sep 19, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/34792
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical encoder has an optically-encoded plate having parallel tracks each comprising alternate opaque, reflective regions and transparent, non-reflective regions which differ in length between the tracks. LED's direct radiation onto one side of each track. Detectors located on one side of the plate provide an output in response to radiation reflected from the reflective regions of each track; detectors located on the opposite side of the plate provide an output in response to radiation transmitted through the transparent regions. The outputs from the detectors are normally complementary. A processor detects any loss of complementarity and determines the position of the plate close to the boundary between adjacent regions by comparing the detector outputs as one falls and the other rises.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.