Focus error detecting device

Details Focus error detecting device Focus error detecting device

1995-04-26

1996-07-02

Young, W. R.

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

369 44420, 369120, G11B 709

Patent

active

055329870

ABSTRACT:
A focus error detecting device includes a reflected beam obscurer and a two-division photodetector. The observer obscures a part of the reflected beam. The two-division photodetector includes first and second light receiving sections separated from each other by a division band region which receive the reflected light beam not obscured by the obscurer. A focus error signal is produced based on the output of each light receiving section. Each light receiving section has an array of tapered projections along its edge in the division band region. Alteratively, the light receiving sections have a main part with an edge coincident with an edge of the division band region, and groups of light receiving stripes extending in a direction parallel with the edges of the main part.

REFERENCES:
patent: Re33548 (1991-03-01), Kime
patent: 4079248 (1978-03-01), Lehureau et al.
patent: 5161139 (1992-11-01), Inoue et al.
patent: 5173890 (1992-12-01), Miyake et al.
patent: 5270996 (1993-12-01), Ono
Bouwhuis, "Principles of Optical Disk System", Adam Hilger (1985), pp. 77-79.
Irie, "Focus Sensing Characteristics of the Pupil Obscuration Method for Continuously Grooved Disks", Proc. Int. Symp. on Optical Memory, 1987, Japanese Journal of Applied Physics, vol. 26 (1987), Supplement 26-4, pp. 183-186.

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