# US 8,570,846 B2 · Focus jump method for optical disk device and multi-layer disk

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- Number: US 8,570,846 B2
- Document ID: US8570846B2
- Status: Granted
- Kind: B2
- Application number: 12/609,797
- Filed: 2009-10-30
- Published: 2010-10-21
- Granted: 2013-10-29
- Earliest claimed: 2009-04-16
- Assignees: Hitachi Consumer Electronics Co., Ltd.
- Applicants: Takeyoshi Kataoka
- Inventors: Takeyoshi Kataoka
- Web page: https://patentgrep.com/patent/US8570846B2

## CPC

- G11B 7/08511: {with focus pull-in only}
- G11B 2007/0013: {for carriers having multiple discrete layers}
- 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 device for recording/reproducing information on/from a multi-layer optical disk moves a light focusing point for several layers by one focus jump. The optical disk device includes a controller to detect a level of a focus error signal to change an output level of a focus drive signal, and the controller changes timing to change the output level of the focus drive signal based on the number of layers for the focus jump.

## Claims

### Claim 1

An optical disk device for reproducing information from an optical disk and/or for recording information on an optical disk by use of a laser beam, comprising:
an objective lens for focusing the laser beam;
an actuator for driving the objective lens;
a photodetector for detecting reflected light from the optical disk;
focus error signal (FES) generating means for generating a focus error signal from the reflected light detected by the photodetector;
control means for generating and outputting a focus drive signal to control the actuator; and
actuator drive means for amplifying the focus drive signal and supplying power to the actuator,
wherein
the control means sets, in a multi-layer focus jump in which the optical disk includes at least three layers of information recording planes and the control means moves a light focusing point of the laser beam at least two layers of the optical disk, timing for a change in an output level of the focus drive signal based on the number of layers for the focus jump;
wherein the timing for a change in an output level of the focus drive signal is when a maximal value or a minimal value of the focus error signal is detected or when the focus error signal reaches a reference level; and
wherein when the output level of the focus drive signal is changed at detection of the maximal value and the minimal value of the focus error signal, conditions for the maximal value and the minimal value are reversed between a first case in which the number of the layers for the focus jump is odd and a second case in which the number of the layers for the focus jump is even.