US05003521Optical disk discriminating device
AssigneeSony Corporation
Assign./FiledMarch 26, 1991/ Aug. 18, 1988
InventorsYoshida; Tadao, Fujiie; Kazuhiko, Ando; Ryo
SummaryDiscriminating between recordable and pre-recorded discs.
AbstractAn objective lens (3) of an optical pick up head (10) is moved in a direction of the optical axis, and a signal level of the output detected by the optical pick up head (10) before and after a focussed state is compared with predetermined reference levels (Vref<SUB>1</SUB>) and (Vref<SUB>2</SUB>) level comparators (32) and (33), In order to discriminate the reproduction-only disk from the recording disk by utilizing a difference in the reflection factor on the recording surface on the optical disk (20). Operation of the optical disk recording/reproducing apparatus is automatically switched over depending upon the kind of the optical disk.