Optical encoder and scale for encoder
US6914234B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 2002 |
| Grant date | Jul 5, 2005 |
| Priority date | — |
| Expiry date | Apr 18, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/34715
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Laser light output from a laser light source is irradiated onto a transmission-type scale. Due to movement of the transmission-type scale, a polarization angle of transmitted light varies in accordance with variations in orientations of half-wave plates arrayed in a longitudinal direction. It is difficult for the polarization angle to be affected by noise factors such as external light or the like. Light intensity of a polarized light component, which is transmitted through an analyzer and detected at a photo-detector, varies in accordance with the polarization angle. Thus, the light intensity varies as the transmission-type scale moves, and a detection signal is output to a movement amount computing device. When an amount of movement is computed on the basis of the signal, the exact amount of movement can be detected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.