Sync detection device for an optical disk player and method...

Details Sync detection device for an optical disk player and method... Sync detection device for an optical disk player and method...

1998-12-22

2003-05-06

Chin, Stephen (Department: 2634)

Pulse or digital communications

Synchronizers

C375S368000, C375S376000

Reexamination Certificate

active

06560302

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 74181/1997, filed Dec. 26, 1997, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk player, and in particular, to a sync detection device for detecting and generating a sync signal from a signal read from an optical disk.
Known optical disk players includes a sync detection and protection device for detecting a sync signal. The sync detection and protection device minimizes damage to data read from an optical disk.
FIG. 1
is a block diagram of a conventional optical disk player. A pickup
102
reads data recorded on an optical disk
100
and generates an RF (Radio Frequency) signal according thereto. The pickup
102
provides an RF amplifier (RF Amp.)
104
with the RF signal. The RF amplifier
104
amplifies the RF signal and provides the amplified RF signal to a binarizer
106
. The binarizer
106
comprises a comparator which converts an RF signal into a string of “1s” and “0s” based upon a level of the RF signal. The binarizer
106
binarizes the output of the RF amplifier to generate serial binary data (SDATA). The SDATA is output to a sync detection and protection device
110
. The sync detection and protection device
110
receives the SDATA and a playback clock signal (PLCK) generated from a voltage controlled oscillator (VCO)
108
. The sync detection and protection device
110
detects a sync signal from the SDATA and the PLCK signals, and protects the detected sync signal. In case the sync signal is not detected successfully, the sync detection and protection device
110
inserts a sync signal (i.e., generates a sync insertion signal).
The PLCK signal and SDATA are also applied to a phase detector
112
. The phase detector
112
compares a phase of the PLCK signal with a phase of the SDATA to detect a phase difference therebetween. The comparison results, i.e., the detected differences, are fed back to the VCO
108
via a lowpass filter
114
. When a defect is detected (by a detect detector not shown), the lowpass filter
114
holds its output value. The VCO
108
generates the playback clock (PLCK) according to the output of the lowpass filter
14
, in sync with the data read from the disk
100
.
FIG. 2
is a block diagram of the sync detection and protection device
110
. The sync detection and protection device
110
includes a sync detector
116
and a sync insertion and protection device
124
. The sync detector
116
generally comprises: a register
118
; a sync pattern decoder
120
; and a sync generator
122
. The register
118
generally comprises: a serial-input-parallel-output register. The register
118
receives the SDATA, in series, according to the PLCK, and outputs the loaded binary data (SDATA), in parallel, to the sync pattern decoder
120
. The sync pattern decoder
120
checks whether the SDATA coincides with the sync pattern and generates a sync detection signal to the sync generator
122
if the SDATA is coincides with the sync pattern.
The sync insertion and protection device
124
counts the playback clock signal (PLCK), and generates a sync protection window signal to the sync generator
122
when the count value corresponds to a position where the sync signal is to be generated. The sync generator
122
checks whether the sync detection signal is generated during generation of the sync protection window signal. The sync generator
122
outputs a sync detection signal, as the sync signal, if the sync detection signal is generated during generation of the sync protection window signal. However, if the sync detection signal is not generated during generation of the sync protection window signal, the sync generator
122
requests the sync insertion and protection device
124
to generate a sync insertion signal, and outputs the sync insertion signal as the sync signal. After outputting a predetermined number of sync insertion signals, the sync generator
122
resets the sync insertion and protection device
124
.
In such a conventional system, after the sync protection window signal is out of sync with the sync detection signal, even though the sync detection signal is generated normally, it is unavoidable that the predetermined number of the insertion sync signals will be generated.
Further, after generation of the predetermined sync insertion signals, the sync protection window is reset according to the sync detection signal. At this moment, sync noises may be unexpectedly generated. If sync noises are generated, the sync protection window is erroneously set, and the subsequently generated normal sync detection signals may be misjudged as erroneous sync detection signals. Based on this misjudgment, the sync insertion and protection device
124
will erroneously generate the predetermined number of the sync insertion signals causing damage to the data.
Finally, when a defect is detected, the lowpass filter
114
holds its output. If the held output value is not coincident with an average value, the playback clock PLCK from the VCO
108
becomes out of sync (shifted), which leads to a shift of the positions where the sync protection window signal and the sync insertion signal are generated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a sync detection device which stops generating sync insertion signals when a sync detection signal is normally generated after a sync protection window signal goes out of sync with the sync detection signal.
It is another object of the present invention to provide a sync detection device for preventing a sync protection window from being set according to sync noises.
It is still another object of the present invention to provide an optical disk player which prevents a playback clock from being out of sync even when a defect is detected.
According to an aspect of the present invention, a sync detection device for an optical disk player includes a sync detector for detecting a sync signal from a signal read from an optical disk; a sync insertion and protection device for setting a sync protection window according to a sync detection signal from the sync detector in response to a reset signal, counting a playback clock generated from a voltage controlled oscillator to generate a sync protection window signal if the count value is coincident with a position where the sync signal is to be generated, and generating a sync insertion signal in response to a sync insertion request; a sync generator for outputting the sync detection signal if the sync detection signal is in sync with the sync protection window signal, and requesting the sync insertion and protection device to generate the sync insertion signal to output the sync insertion signal if the sync detection signal is out of sync with the sync protection window signal; and a sync noise canceller for counting the playback clock during generation of the sync detection signal, and generating the reset signal to the sync insertion and protection device if the count value reaches a predetermined value.


REFERENCES:
patent: 4471299 (1984-09-01), Elmis
patent: 5293275 (1994-03-01), Kawasaki
patent: 6101230 (2000-08-01), Chun et al.
patent: 59-221809 (1984-12-01), None
patent: 61-180967 (1986-08-01), None
patent: 2-206070 (1990-08-01), None
patent: 4-13280 (1992-01-01), None
patent: 6-13897 (1994-01-01), None

Affiliated with

Also associated with

Rating

Sync detection device for an optical disk player and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Sync detection device for an optical disk player and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sync detection device for an optical disk player and method... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3005720