Invention Grant
- Patent Title: Disc device
- Patent Title (中): 光盘设备
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Application No.: US12054426Application Date: 2008-03-25
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Publication No.: US07660223B2Publication Date: 2010-02-09
- Inventor: Kouji Fujita
- Applicant: Kouji Fujita
- Applicant Address: JP Tokyo
- Assignee: Hitachi, Ltd.
- Current Assignee: Hitachi, Ltd.
- Current Assignee Address: JP Tokyo
- Agency: Antonelli, Terry, Stout & Kraus, LLP.
- Priority: JP2007-141270 20070529
- Main IPC: G11B7/00
- IPC: G11B7/00

Abstract:
A disc device includes a lens that focuses a laser light on an optical disc surface, a focus drive unit that drives the lens in a focusing direction, a focus control unit that controls to focus the laser light on the optical disc surface, a focus displacement detecting unit that detects a displaced amount in the focusing direction, a differentiation unit that differentiates a focus displacement detected signal, and a unit that inverts a sign of a differentiated signal, thereby, the disc device is driven intermittently to restrain a motion of an objective lens in a focusing direction and avoid colliding the objective lens with the optical disc surface.
Public/Granted literature
- US20080298211A1 Disc Device Public/Granted day:2008-12-04
Information query
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