发明授权
US06788644B1 Devuce and method for forming a focus error signal based on ohase difference between corresponding parts of detector signals
失效
基于检测器信号的相应部分之间的差值形成聚焦误差信号的方法和方法
- 专利标题: Devuce and method for forming a focus error signal based on ohase difference between corresponding parts of detector signals
- 专利标题(中): 基于检测器信号的相应部分之间的差值形成聚焦误差信号的方法和方法
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申请号: US09332239申请日: 1999-06-14
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公开(公告)号: US06788644B1公开(公告)日: 2004-09-07
- 发明人: Josephus J. M. Braat
- 申请人: Josephus J. M. Braat
- 优先权: EP98201986 19980615
- 主分类号: G11B724
- IPC分类号: G11B724
摘要:
A device scans an optical record carrier having optically detectable marks along a track. The device includes a radiation source for emitting a radiation beam, an objective system for guiding the radiation beam to the record carrier, and a radiation-sensitive detection system for receiving radiation from the record carrier. The detection system includes at least two detectors on both sides of a dividing line. Each detector has an output for providing a detector signal. An electronic circuit forms a focus error signal from the detector signals. The electronic circuit determines a time or phase difference between corresponding parts of the detector signals relating to passage of the radiation beam over patterns of the marks having a spatial frequency in a first range and in a different, second range, and forms a focus error signal in dependence on the time or phase difference.