Automatic dithering optical focusing system using an oscillating mirror in the path of the radiation beam
US4074312A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 1, 1976 |
| Grant date | Feb 14, 1978 |
| Priority date | — |
| Expiry date | Mar 1, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0927
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An automatic optical focusing system suitable for an apparatus for reading an information track on a record carrier with the aid of a read spot which is focused in an imaginary focusing plane and which is formed by a radiation beam which is produced by a radiation source, more in particular suitable for a video disc player which employs optical reading, and serving for automatically keeping the read spot focused at the plane in which the information is disposed (information plane) during playing of a record carrier, comprising an optical focusing device, an oscillating optical element which cooperates with the radiation beam and which can effect high-frequency oscillations so that a high frequency oscillation of small amplitude about the coarse position of the focusing plane is obtained, an electromagnetic drive system for the high-frequency drive of the oscillating optical element, a radiation-sensitive detector which responds to the radiation beam which has been modulated by the information track, and a control circuit for producing a control signal which depends on the output signal of the detector, which control signal is applied to the control coil of the optical focusing devi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.