Disk apparatus having a read error retry function

Details Disk apparatus having a read error retry function Disk apparatus having a read error retry function

1993-02-22

1995-01-31

Hajec, Donald

Dynamic information storage or retrieval

Binary pulse train information signal

Binary signal gain processing

360 51, 360 32, G11B 502, G11B 509, G11B 576

Patent

active

053864050

ABSTRACT:
A disk apparatus having a readout circuit for providing readout data signals and capable of immediately detecting runaway of a readout clock signal generated from a VFO (Variable Frequency Oscillator) in the readout circuit if such occurs. The disk apparatus is free from a read error due to a permanent defect on a disk, e.g., an optical disk, or other causes. The disk apparatus includes a head for picking up signals from a disk, and a readout circuit for providing a readout signal and a readout clock signal, including a digitizing circuit for receiving and digitizing a data signal picked up by the head into a binary data signal, a reference clock generator for generating a reference clock signal and a variable frequency oscillator for receiving a read-gate signal, the digitized binary data signal and the reference clock signal and generating a readout data signal and a readout clock signal, each synchronized with the reference clock signal. The disk apparatus further includes a detecting circuit for supplying the read-gate signal to and receiving the reference clock signal and the readout clock signal from the readout circuit and for detecting that a synchronizing operation in the variable frequency oscillator is in an abnormal state and resetting the read-gate signal when a frequency difference between the reference clock signal and the readout clock signal exceeds a predetermined value.

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patent: 5233482 (1993-08-01), Galbraith et al.
patent: 5233589 (1993-08-01), Saito et al.

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