Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Patent
1996-07-15
1998-05-05
Nelms, David C.
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
369 54, 369124, G11B 700
Patent
active
057485879
ABSTRACT:
A spindle servo circuit in an optical disc reproducing apparatus operates with enhanced stability at disc rotation speeds substantially higher than normal. The spindle servo circuit includes a first phase comparator which compares the phases of a reference clock signal and a reproduced frame clock signal and outputs a phase difference signal. The spindle servo circuit also includes a first low pass filter for generating a revolution speed control signal for a spindle motor by low-pass filtering the phase difference signal. The revolution speed control signal is input to a motor driving means for driving revolution of a spindle motor, which in turn spins the optical disc. Optical signals are picked up off the disc and run through a high frequency amplifier for amplifying and wave-shaping to produce a reproduction data signal. A phase locked loop circuit generates a reproduced bit clock signal from the reproduced data signal during normal operation, and during high speed operation (above a predetermined speed) generates the reproduced bit clock signal corresponding to a previous state. Thereby, in the spindle servo control system for operating at higher than normal speed, according to the present invention, the servo control system can be maintained in a stable state by fixing the phase synchronous loop of an accurate servo control system at a predetermined high speed, to allow stable restoration of data when operating at high speed.
REFERENCES:
patent: 5508983 (1996-04-01), Nakmura et al.
patent: 5521895 (1996-05-01), Miura et al.
patent: 5528574 (1996-06-01), Takeuchi et al.
patent: 5636192 (1997-06-01), Shimizume et al.
Chu Kim-Kwok
Nelms David C.
Samsung Electronics Co,. Ltd.
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