| 摘要 |
PROBLEM TO BE SOLVED: To detect a tracking error signal with an optimum detection system for recordable/reproducing exclusive disks with different structures by mounting plural objective lenses on an axial slide type actuator and properly switching them. SOLUTION: Output signals from light receiving surfaces 9i-9l are suited to light intensity modulation signals of respective areas four dividing reflection luminous flux from an optical disk to a square with cross shape, and these are operated prescribedly by a phase difference detection circuit 202 through a signal delay circuit 201, and the tracking error signal in a DPD system is detected. Further, since the sum signals of respective output signals of the light receiving surfaces 9i and 9j, 9k and 9l are suited to the light intensity modulation signals of respective areas bisecting the disk reflection luminous flux in the radial direction, a difference signal of them is detected by an operational amplifier 204, and the tracking error signal is detected. In such a manner, respective light receiving surface output signals of a detector 9 are operated prescribedly, and a focus error signal and two kinds of tracking error signals by different detection systems are obtained simultaneously, and these are selected according to whether the disk is a recordable type or a reproducing exclusive type. |
