Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
2011-08-09
2011-08-09
Hindi, Nabil Z (Department: 2627)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S124120, C369S047100
Reexamination Certificate
active
07995432
ABSTRACT:
Deterioration of error rate at reproduction time is prevented even if a photodetector with a poor characteristic is included. An optical pickup unit (3) is provided with 4 photodetectors. A controller (13) obtains an error correction result of a reproduced signal, which is reproduced based on an RF signal generated while changing combination of the 4 photodetectors at startup time, and determines a combination at reproduction time in accordance with the obtained error correction result, to be given to an RF amplifier unit (10). The controller (13) is provided with a counter that counts for a fixed time period the error correction result per combination of the photodetectors, a comparator that compares a count result of the counter with a threshold set in advance, and an output controller that judges whether or not to use a combination of the photodetectors based on a comparison result of the comparator and performs change control of the combination of the photodetectors, of which there is a plurality. At reproduction time, control is performed to obtain the reproduced signal from output outside of the photodetector with the poor characteristic.
REFERENCES:
patent: 6392967 (2002-05-01), Nakayama et al.
patent: 7224648 (2007-05-01), Takaba
patent: 2007/0217317 (2007-09-01), Saito
patent: 2007-257677 (2007-10-01), None
Hindi Nabil Z
McGinn IP Law Group PLLC
Renesas Electronics Corporation
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