发明名称 |
AN OPTICAL PICKUP DEVICE |
摘要 |
<p>A focusing error detecting apparatus having a first photo-detector (7a) of which the light receiving portion is halved to provide first (7a4) and second (7a5) light receiving portions asymmetrical with respect to the center of a beam spot of a bundle of incident laser beams, the first photo-detector (7a) being located in the optical path ahead of the focusing point of the bundle of the incident laser beams, a second photo-detector (7b) of which the light receiving portion is halved to provide first (7b4) and second (7b5) light receiving portions asymmetrical with respect to the center of a beam spot of a bundle of incident laser beams, the second photo-detector (7b) being located in the optical path behind a focussing point of the bundle of the incident laser beams and a calculating circuit (3) for calculating a difference between a difference of detected outputs from the first and second light receiving portions of the first photo-detector and a difference of detected outputs from the first and second light receiving portions of the second photo-detector, thereby to derive a focusing error signal from the output of the calculating circuit (3).</p> |
申请公布号 |
EP0301792(B1) |
申请公布日期 |
1993.09.15 |
申请号 |
EP19880306830 |
申请日期 |
1988.07.25 |
申请人 |
SONY CORPORATION |
发明人 |
YOSHITOSHI, YOU;KUME, HIDEHIRO;MATSUMOTO, YOSHIYUKI;MITSUMORI, KOJI;YAMAMOTO, ETSUFUMI;OINOUE, HIROSHI |
分类号 |
G02B7/28;G11B7/09;G11B7/12;G11B7/13;G11B7/135 |
主分类号 |
G02B7/28 |
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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