| 摘要 |
PURPOSE:To attain the record/reproduction of disks having different recording systems through the same recording/reproducing device, by controlling the polarity of a record signal based on the result of detection of a polarity deciding mark for record signal provided to an optical disk. CONSTITUTION:When an optical disk is loaded to a disk motor 7, a controller (not shown in the figure) consisting of a microcomputer detects the loading of the disk. Then a command of revolution is delivered to the motor 7. An FF21 is cleared by the rise of said command. If a polarity reverse mark 17 exists to show that the optical disk has an erasion function, a photodiode 19 detects the mark 17. This detection signal is compared with the reference voltage VTH by a comparator 20 and delivered in the form of a pulse. This pulse output latches FF outputs Q and Q'. Then the output of a modulator is inverted and delivered by a logic signal reverse logic 22. Thus even an optical disk of an erasable whitening record system can obtain the reproduction signal output of the same polarity as the output of the modulator obtained in a record mode. As a result, the stable reproduction is possible with a preamplifier, a signal processing circuit and a demodulator which have systems equal to a blackening record system. |
