Optical focus position control in optical disc apparatus
US4660190A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 6, 1983 |
| Grant date | Apr 21, 1987 |
| Priority date | — |
| Expiry date | Sep 6, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10504
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Disclosed below is a control device for positioning an optical focus in an optical disc apparatus that records, plays back, and erases any information by irradiating optical beams such as the laser beams onto a recording media composed of magnetic film, wherein the control device is characterized in that; it incorporates a focussing permanent magnet that makes up a closed magnetic circuit, a focussing yoke plate, a focussing yoke, and a focussing device coil installed so that it crosses a focussing magnetic space existing that exists between the focussing yoke plate and the focussing yoke so that the focussing magnetic space can be created in an area close to the recording media which is installed in the closed magnetic circuit. In addition, the optical focus position control device that executes both the tracking and focussing control operations for the optical disc apparatus also includes mechanism that drives the objective lens in the direction of dual axes, i.e., in the vertical (up/down) and horizontal (left/right) directions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.