Apparatus for detecting delete patterns of optical discs

Details Apparatus for detecting delete patterns of optical discs Apparatus for detecting delete patterns of optical discs

1989-02-21

1991-07-02

Envall, Jr., Roy N.

Dynamic information storage or retrieval

Binary pulse train information signal

Binary signal gain processing

369 58, 369 56, 369100, 369116, G11B 700, H04B 900, H04N 584

Patent

active

050291521

ABSTRACT:
A circuit for detecting delete patterns of an optical disc, the delete pattern overwriting data on a sector of an optical disc to delete previously written data of the sector, the delete pattern having a predetermined pulse width, period and number of pulses. The read-out signal from the sector is digitized with a predetermined slice level. The delete pattern is detected from the digitized signal by measuring pulse width to determine if the delete pulse width is present, by measuring the period between the pulses to determine if the delete period is present, and by measuring the number of pulses to determine if the delete number of pulses is present. According to one or more of these determinations, the delete state of the sector may be detected. The false delete state caused by dust, etc., distorting the read analog signal is detected by providing a peak pulse signal from the read-out analog signal and the data signal, and interleaving this peak pulse signal with the digital signal to produce a combined signal fed to the various detectors for determining one or more of the pulse width, period, and number, so that the delete pattern and thereby the delete state may be detected in a highly reliable manner to prevent the erroneous detection of false delete patterns that are produced by valid data.

REFERENCES:
patent: 4881215 (1989-11-01), Horie
"Explanatory Note on the Sector Format for Continuous Servo Method", Jun. 1987, Continuous Servo Working Group in Japan.

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