Data reproduction apparatus having a variable synchronization detection window
A fast synchronization pull-in and an optimum error correction are achieved in a reproduction apparatus for reproducing data recorded on a recording medium even in the case where the quality of input data involving a seek or defect is low. A seek amount detection block 190 is provided, a seek change signal 201 is generated, and the width of a synchronization detection window pulse 161 and a correction algorithm in a correction block 230 are modified.
1. A data reproduction apparatus comprising:
reproduction means of reproducing data recorded in the recording medium;
clock count means of counting clocks based on the data reproduced from said recording medium;
window generation means of estimating the position of a synchronization signal in said reproduced data based on the count value of said clocks and generating a synchronization detection window signal having a predetermined width including the estimated position, wherein said window generation means detects said defect, and if the width of said window signal is changed, continues to change the width of said synchronization detection window signal for a predetermined period of time after the detection of said defect ends;
synchronization signal detection means of detecting the synchronization signal from the data reproduced from said recording medium by searching within said synchronization detection window; and
defect detection means of detecting a defect on said recording medium based on the data reproduced from said recording medium;
wherein said window generation means changes the width of said synchronization detection window signal at least for a period of time during which said defect is detected; and
wherein said window generation means detects said defect, and if the width of said window signal is changed, continues to change the width of said synchronization detection window signal for a predetermined period of time after the detection of said defect ends.
2. The data reproduction apparatus according to claim 1 , wherein said defect detection means determines the type and/or size of said defect and said window generation means changes the quantity of a change in the width of said synchronization detection window signal according to said determined type and/or size of said defect.
3. The data reproduction apparatus according to claim 1 , wherein said predetermined period of time is a time period from the completion of the detection of said defect to the time when said synchronization signal is detected with stability.
4. The data reproduction apparatus according to claim 1 , wherein said synchronization signal detection means changes said criteria for detecting said synchronization signal according to the detection of said defect.
5. The data reproduction means according to claim 1 , wherein said window generation means comprises a rewritable register and changes the width of said synchronization detection window signal by a width set in said register.
6. The data reproduction apparatus according to claim 1 , wherein said defect detection means analyzes the envelope of an RF signal read from said storage medium to detect said defect.
7. A computer readable medium including instruction to cause a computer to perform a data reproduction method, the method comprising the steps of:
counting clocks based on the data reproduced from a recording medium;
estimating the position of a synchronization signal in said reproduced data based on the count value of said clocks;
generating a synchronization detection window signal having a predetermined width including the estimated position;
detecting the synchronization signal from the data reproduced from said recording medium by searching within said synchronization detection window; and
detecting a defect on said recording medium based on the data reproduced from said recording medium;
wherein said generating step includes detecting said defect, changing the width of said synchronization detection window signal at least for a period of time during which said defect is detected, and if the width of said widow signal is changed, continuing to change the width of said synchronization detection widow signal for a predetermined period of time after the detection of said defect ends.