| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve such a problem that when recording or reproducing for an optical disk with the multilayer recording layers is performed, an unwanted light reflected by the recording layer other than a target layer of recording/reproducing and original signal light are overlapped on a light receiving layer of a photodetector, an unwanted disturbance component is leaked to a detected signal by the interference, this disturbance component, especially, affects bad influence on detection of a sub-push-pull signal in a differential push-pull system, consequently, signal quality of the tracking control signal in the DPP system is deteriorated remarkably. <P>SOLUTION: A light shield band or a dead zone having the prescribed width are provided on a dividing line in a light receiving area in which the sub-push-pull signal in the photodetector is detected to improve the problem. Thereby influence of the disturbance component caused by interference can be reduced satisfactorily. <P>COPYRIGHT: (C)2008,JPO&INPIT |
