Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – Mechanism control by the control signal
Patent
1987-10-05
1989-03-21
Richardson, Robert L.
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
Mechanism control by the control signal
250201, G11B 700
Patent
active
048150606
ABSTRACT:
In an optical pickup device for a compact disk or the like, the photodetector is divided into four regions by three parallel division lines. A focus error signal is produced by forming the difference between the sum of the outputs of the inner two regions and the sum of the outputs of the outer two regions, while a tracking error signal is generated by forming the difference between the outputs of one of the outer regions and its adjacent inner region. The sum of the widths of the two inner regions is set such that the focus error signal is zero when the reflected beam is in focus on the disk. The direction of movement of the track is inclined with respect to the division lines so that the differences in outputs from each of the adjacent inner and outer regions is zero or a minimum. The direction of movement of the light beam during tracking is parallel to the division lines.
REFERENCES:
patent: 4682315 (1987-07-01), Uejima
patent: 4700334 (1987-10-01), Shinkai
Search Report of West German Patent Office.
Pioneer Electronic Corporation
Richardson Robert L.
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