Focusing-error detecting apparatus with a simple photodetector u

Details Focusing-error detecting apparatus with a simple photodetector u Focusing-error detecting apparatus with a simple photodetector u

1991-09-20

1992-09-01

Envall, Jr., Roy N.

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

369 4423, 369 4437, 369103, G11B 700

Patent

active

051446065

ABSTRACT:
A light source emits a light beam. A focusing optical system focuses the light beam on an information recording medium. First and second strip-shape photodetectors approximately extend on a common plane. First and second return light beams are generated on the basis of a light beam reflected and diffracted back from the medium. The return light beams have different focal points. Centers of the return light beams are received by the photodetectors respectively. The focal points of the first and second return light beams lie at a front side and a rear side of light-receiving surfaces of the first and second photodetectors respectively when sizes of the return light beams on the light-receiving surfaces of the photodetectors are equal. A focusing-error signal is generated in response to a difference between output signals from the first and second photodetectors. The first and second photodetectors extend approximately in parallel. The first and second photodetectors have approximately equal widths which agree with a value W.sub.x. A distance "d" between centers of the first and second return light beams on the first and second photodetectors is equal to or smaller than a sum of a value D and the value W.sub.x which is measured along a direction parallel to a line connecting the centers of the first and second return light beams. The value D is equal to diameters of the first and second return light beams on the first and second photodetectors when the diameters of the first and second return light beams on the first and second photodetectors are equal.

REFERENCES:
patent: 4712205 (1987-12-01), Smid et al.
patent: 4718052 (1988-01-01), Kondo et al.
patent: 5004900 (1991-04-01), Seya et al.

Affiliated with

Also associated with

Rating

Focusing-error detecting apparatus with a simple photodetector u does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Focusing-error detecting apparatus with a simple photodetector u, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Focusing-error detecting apparatus with a simple photodetector u will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-773894