Optical type displacement detecting device
US4912322A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 7, 1987 |
| Grant date | Mar 27, 1990 |
| Priority date | — |
| Expiry date | Aug 7, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/36
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical type displacement detecting device including a main scale and an index scale, wherein a pitch of a first optical grating formed on the main scale is set at P and a pitch of a second optical grating formed on the index scale is set at P/n, thereby producing divided detection signal having pitch P/n. Furthermore, the pitch of the second optical grating is set at (u+v) P/u or (u+v) P/(2u) (u is a gap between a diffusive light source and the first optical grating and v is a gap between the first and second optical gratings), so that a collimator lens can be dispensed with. Further, higher harmonic components of the first optical grating are utilized, whereby the pitch of the second optical grating is set at substantially (u+v) Q/u or (u+v) Q/(2u) (Q=P/m, and m is a whole number of 2 or more), thereby preventing the pitch of the second optical grating from being divided into small ones.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.