| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical recording and reproducing apparatus which stably and inexpensively performs focusing control and tracking control. SOLUTION: Respective regions A to F of photodetectors 20 and 21 output electric signals (a) to (f) meeting the amount of reflected light from an optical disk 1. The electric signals (a) to (f) are inputted via an RF amplifier section 30 to A/D converters 40 to 45. An arithmetic circuit 50 forms a focal error signal FE and a tracking error signal TE by performing arithmetic operation of the electric signals (a) to (f). A CPU 60 measures the DC level of the output signals of the A/D converters 40 to 45 and sends control signals OCa to OCf to a variable resistor of the RF amplifier section 30 in such a manner that the difference between the DC level and the central value of the dynamic range of the A/D converters attains "0". The CPU 60 sends control signals GCa to GCf to the variable resistor of the RF amplifier section 30 in such a manner that the output amplitude of the output signals is confined within the dynamic range. COPYRIGHT: (C)2005,JPO&NCIPI
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