发明名称 |
Optical information recording/reproducing apparatus, and optical head apparatus |
摘要 |
To reduce an effect of reflected light from a layer (or layers) other than a layer to be read upon focus position control when reading a multilayer optical disk in an optical disk drive. In an optical system where a focus error signal is generated by the knife edge method, a photodetector 53 that is divided into four parts is used. Each of two pairs of light detecting elements on the right or left side are formed by division of a detection plane of the photodetector such that the reflected light from a neighboring layer falls half-and-half on that pair of the light detecting elements. Signals from the photodetector are given with alternating polarities in such a way that any adjacent light detecting elements have mutually different polarities and are added up together to form the focus error signal.
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申请公布号 |
US6563099(B2) |
申请公布日期 |
2003.05.13 |
申请号 |
US20010925311 |
申请日期 |
2001.08.10 |
申请人 |
HITACHI, LTD. |
发明人 |
KIMURA SHIGEHARU;SHIMANO TAKESHI;ARIYOSHI TETSUO |
分类号 |
G11B7/00;G11B7/09;G11B7/13;G11B7/135;(IPC1-7):G02B27/40 |
主分类号 |
G11B7/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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