| 摘要 |
PURPOSE:To reproduce a different kind of a disc by a disc drive and a signal processing circuit by selecting an output of a differential means when a special kind of disc is detected and selecting an output of an adder means when other kind of disc is detected. CONSTITUTION:When a special kind of disc is detected by a detection means, an output of a differential means is selected and when other kind of disc is detected, an output of an adder means is selected by a selecting means. For example, when a disk in use is an optical disc or a ROM type disc, since no notch is provided to a side face of a disc cartridge 11, a microswitch 13 is turned on, a control signal C of an analog switch 24 is logical O, the analog switch is thrown to the position of contact (b). Since the contact (b) is connected to a non-inverting inpu of a differential amplifier 23, the differential amplifier 23 constitutes an adder as a whole.
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