# US 5,347,506 A · Optical disk player including a plurality of independent pick-ups

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- Number: US 5,347,506 A
- Document ID: US5347506A
- Status: Granted
- Kind: A
- Application number: 07/968,529
- Filed: 1992-10-29
- Granted: 1994-09-13
- Earliest claimed: 1991-11-01
- Assignees: Fujitsu Limited
- Inventors: Yasunori Matsudo; Hisashi Naka
- Web page: https://patentgrep.com/patent/US5347506A

## CPC

- G11B 20/10: Digital recording or reproducing
- G11B 7/005: Reproducing (G11B7/0065 takes precedence)
- G11B 7/14: specially adapted to record on, or to reproduce from, more than one track simultaneously
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

An optical disk player for simultaneously reading data recorded on different areas of the optical disk is disclosed. The optical disk player provides a plurality of pairs of optical pick-ups and pick-up positioning mechanisms. A rotational speed of the optical disk is controlled according to a synchronization signal obtained from a first pick-up and the first pick-up can read the recorded data by a normal method, however, other pick-ups need to change read rates according to respective linear velocity. Therefore, reading speed changing circuits are provided for each of the optical pick-ups except a first pick-up and they change read rates according to linear velocities of the optical disk at reading positions.

## Claims

### Claim 1

An optical disk player for simultaneously reading a plurality of data respectively recorded on a plurality of recording areas of an optical disk, comprising:
a plurality of optical pick-ups for reading said data; said plurality of optical pick-ups including a first optical pick-up and at least one other optical pick-up;
a plurality of pick-up positioning mechanisms which are respectively provided for each of said plurality of optical pick-ups, and independently move corresponding ones of said plurality of optical pick-ups;
reading speed changing means which are respectively provided for each of said at least one other optical pick-up, and which change read rates of said at one other optical pick-up according to linear velocities of said optical disk at reading positions of said at least one other optical pick-up.

### Claim 2

An optical disk player for simultaneously reading a plurality of data respectively recorded n a plurality of recording areas of an optical disk, comprising:
a plurality of optical pick-ups for reading said data; said plruality of optical pick-ups including a first optical pick-up and at least one other optical pick-up;
a plurality of pick-up positioning mechanisms which are respectively provided for each of said plruality of optical pick-ups, and independently move corresponding ones of said plurality of optical pick-ups;
reading speed changing means which are respectively provided for each of said at least one other optical pick-up, and which change read rates of said at least one other optical pick-up according to linear velocities of said optical disk at reading positions of said at least one other optical pick-ups; and
a rotation control means for controlling a rotational speed of said optical disk so that said read rate of said first optical pick-up is constant.

### Claim 3 (depends on 2)

An optical disk player as set forth in claim 2, wherein said first optical pick-up is used for reading sound signal data.

### Claim 4 (depends on 2)

An optical disk player as set forth in claim 2, wherein each of said reading speed changing means provides calculation means for calculating a ratio of radii of its own reading position and a reading position of said first optical pick-up, and said reading speed changing means changes said read rate according to said ratio of radii.