Optical disc apparatus for controlling laser power for each zone

Details Optical disc apparatus for controlling laser power for each zone Optical disc apparatus for controlling laser power for each zone

1995-03-22

1996-12-17

Nelms, David C.

Dynamic information storage or retrieval

Specific detail of information handling portion of system

Radiation beam modification of or by storage medium

369 4426, 369100, G11B 700

Patent

active

055860982

ABSTRACT:
An optical disc apparatus using zone record system that successively records data in a plurality of zones without a time lag in switching zones is disclosed. A phase error signal is formed with a reproduced signal of a servo zone of an optical disc 1. A servo clock is generated by a servo PLL 8. Data PLLs 9a and 9b divide the frequency of the servo clock. The laser power of the servo zone is detected by a circuit 11a so as to perform a read ALPC operation. The record laser power is detected by a circuit 11b so as to perform a write ALPC operation. A DSP 14 compares the monitor values and a reference value and controls a bias value of the drive signal so that the detected value becomes equal to the reference value. In write mode, a laser device emits pulse laser light in response to the data clock. Since the write ALPC operation is performed for the next zone while it is performed for the present zone, one of the PLLs 9a and 9b generates data clock for the present zone. The other generates the data clock for the next zone. These data clocks are selectively supplied to the laser device.

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