| 摘要 |
A laser-drive-current control circuit that outputs a drive current indicating signal for indicating a laser drive current for driving a laser light emitting element that emits a laser beam to an optical disk and controls the output of the laser drive current based on a light emission monitor signal, which depends on the output current of a photo-detector that measures the laser light emission power of said laser light emitting element, has a sampling and holding circuit that receives said light emission monitor signal, holds the light emission monitor signal for a predetermined time and then outputs the light emission monitor signal; a recording control pulse generator circuit that generates and outputs a drive current on/off control pulse for controlling the output of the laser drive current at a desired timing and a sample pulse for controlling said sampling and holding circuit at a desired timing based on a modulation signal that specifies marks and spaces on said optical disk; a plurality of automatic power control filter circuits that output control data for converging the output signal of said sampling and holding circuit on a desired value; a hold logic circuit that outputs a signal for holding the logic of said automatic power control filter circuits in synchronization with a write-on signal that specifies recording and reproduction operations on said optical disk; and a bias voltage holding circuit that holds a fixed bias voltage for adjusting said laser drive current, wherein said automatic power control filter circuits hold the logics thereof according to the output signal of said hold logic circuit, and the laser-drive-current control circuit outputs a plurality of drive current indicating signals that indicate said laser drive current based on the output signals of said automatic power control filter circuits and a signal indicating said bias voltage held in said bias voltage holding circuit.
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