Photoelectric angle measuring device
US4792678A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 2, 1987 |
| Grant date | Dec 20, 1988 |
| Priority date | — |
| Expiry date | Oct 2, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01D5/38
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a photoelectric measuring device for measuring the position of two objects which can be rotated relative to each other, a grid located on a graduation support, which is connected with one of the objects, is scanned by a scanning device connected with the other object. To eliminate the eccentricity between the grid and the rotational axis of the graduation support, the light beam emitted by a light source is split in a first graduation area of the grid into two first order diffraction beams, at two diffraction angles. After two-fold deviation by two parallel mirrors, the first order diffraction beams are again joined, in a second graduation area of the grid that lies diametrically opposite the first graduation area. The first order diffraction beams join at the same diffraction angles at which they were emitted from the first graduation area of the grid. Consequently, the beams at the second graduation area are parallel to themselves as they were emitted at the first graduation area.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.