| 摘要 |
PROBLEM TO BE SOLVED: To discriminate the kind of a loaded disk surely and in a short time by discriminating the number of headers in one circuit at the innermost circuit position of the disk. SOLUTION: During the rotation of an optical disk 1, CPU 25 controls a driver 17 from the innermost circuit of the optical disk 1 to a prescribed position to shift the position of a laser beam cast from an optical pickup 2 through an objective lens 3, and executes focusing by a reflected light. At this time, a detection signal of a photodetector of the optical pickup 2 is sent to a servo amplifier 14 through a current/voltage converter 12 and converted into a focus signal therein, and this signal is sent is sent to the motor driver 17 through a DVD servo seek control unit 15 so as to subject the objective lens 3 to a focus control. In the state of focusing, a full addition signal output of an RF amplifier is converted into a digital value as a reflectance by a DVD data processing unit 6, and it is supplied to the CPU 25 to discriminate whether the reflectance is a high one. When it is the high reflectance, discrimination as to CD or DVD-ROM or the like is made from the loaded optical disk 1.
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