Focus servo actuation device for optical recording and reproduction

Abstract

Abstract PURPOSE:To prevent abnormal operation of servo operation by restarting focus servo operation automatically unless normal servo operation is obtained even by turning on the focus servo operation after focus searching operation. CONSTITUTION:A CPU after supplying an on-command to a switch Sw1 supplies a control command to an optical driving system block 4 which moves an optical system block in the radial direction of a disk 1 and a connection command to Sw4 which supplies a tracking error signal Ste obtained during said movement to a waveform detecting circuit 35. When focus servo operation is performed in a normal servo area, a sine wave tracking error signal is obtained and the circuit 35 supplies a normality confirmation and the CPU enters a necessary control sequence. If, however, a servo lock is make in an abnormal servo area, a sine wave signal is not obtained as the signal Ste, so the circuit 352 outputs an abnormal operation detection signal to recommand focus searching operation. Thus, abnormal operation of servo operation is prevented.

Inventors

• 👤 Akio Terada
• 👤 寺田　明生

Bibliographic Details