Method and apparatus for measuring angular displacement of an actuator arm relative to a reference position
US6188484A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 29, 1998 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | Oct 29, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/596
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for directly measuring an angular displacement of an actuator arm relative to a reference position is disclosed, wherein the actuator arm is rotatable about a fixed axis. The apparatus includes a reflection-type diffraction grating, a light source, a transmission-type diffraction grating and a detector. The reflection-type diffraction grating is mounted on the actuator arm. The light source emits a generally rectangularly-shaped laser beam that is aligned to strike the reflection-type diffraction grating to produce reflected beams. The transmission-type diffraction grating, through which the reflected beams pass, causes the reflected beams to converge and form an interference pattern. The detector is positioned to detect the interference pattern and generate a signal representative of the angular displacement of the actuator arm relative to the reference position. A method of directly measuring an angular displacement of an actuator arm relative to a reference position is also disclosed, wherein the actuator arm is rotatable about a fixed axis. The method includes the steps of: (1) providing a reflection-type diffraction grating which is mounted on the actuator arm, th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.