Microprocessor controlled focussing servo acquisition
US4683560A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1983 |
| Grant date | Jul 28, 1987 |
| Priority date | — |
| Expiry date | Dec 15, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/085
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In an auto-focussing system, an actuator which moves together with an objective lens is vertically movable against a rotating optical disc and radiates a light beam so as to form a light spot on an information plane of the disc. A focus servo unit moves the actuator so that an optical distance between the actuator and the disc is within a proper distance region and performs the focus control of the light spot on the disc. While the actuator is approaching the optical disc, an auto-focus/focus servo controller initially makes the servo unit nonoperative and, when the actuator reaches a too-far position in a suitable servo loop distance region specified by a servo loop of the focus servo unit, the controller temporarily stops the movement of the actuator and then moves the actuator again from the too-far position by only a predetermined distance, thereby causing the actuator to be located within the focus loop distance region.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.