Drive current control circuit for laser and optical disk device

Abstract

A laser-drive-current control circuit 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. The circuit has a sampling and holding circuit that receives the signal, holds the signal for a predetermined time and then outputs the signal, a recording control pulse generator circuit that generates and outputs a 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; 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 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 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 filter circuits and a signal indicating said bias voltage held in said bias voltage holding circuit.