Protective device for reader of optical disc player

Abstract

Abstract PURPOSE:To prevent the disc and reader from coming into contact with each other, by detecting that the optical reader is too closely approached to the disc, through the comparison of the signal from two tracking photodetectors with the reference level by addition. CONSTITUTION:When an H signal is input from a terminal 24, a focus motor 12 is driven, the focus lens and disc are brought into contact with each other, and the level of the 1st and 2nd sum signals 6 and 7 of the photodetector 1 is the same when the focus is in coincidence, and the output of a differential amplifier 8 is zero. On the other hand, the output signal of the sum of tracking photodetectors 13, 14 is compared with a given potential at all times at the comparator 17, and the output S is changed as the focus lens approaches the disc. Further, when a focus error signal K is output from the differential amplifier 8, a switch 9 is controlled with the output S of the comparator 17 for the control of the focus motor 12.

Inventors

• 👤 Takashi Okano

Bibliographic Details