Patent ID: 8514679

Claim:
An optical information record/playback device for recording and playing back information by irradiating light onto a recording medium, the optical information record/playback device comprising: a light source; a current driver for supplying current to the light source; an optical system for condensing light from the light source onto the recording medium; a monitoring section for monitoring light emission power of the light source; a current driver control section for controlling output current of the current driver; and an arithmetic/control section for controlling an operation of the current driver control section, wherein: the light source, the current driver, the monitoring section, and a portion of a circuit in the current driver control section form a closed loop circuit for bringing the light emission power of the light source close to a target value based on an output of the monitoring section, the light source, the current driver, and another portion of the circuit in the current driver control section form an open loop circuit for supplying a constant current to the light source, the current driver control section includes a first current source and a second current source, with the closed loop circuit formed, the first current source determines an output current value of the current driver based on information outputted from the arithmetic/control section, with the open loop circuit formed, the second current source determines the output current value of the current driver based on information outputted from the arithmetic/control section, and prior to recording of information by the record/playback device, the arithmetic/control section sequentially conducts a first test light-emission in which the arithmetic/control section causes the light source to emit light with the closed loop circuit being formed, and a second test light-emission in which the arithmetic/control section causes the light source to emit light with the open loop circuit being formed, and the arithmetic/control section compares a first sampling value obtained by sampling the output of the monitoring section in a period during the first test light-emission to a second sampling value obtained by sampling the output of the monitoring section in a period during the second test light-emission, and adjusts an output current value of the second current source such that a difference between the first sampling value and the second sampling value is equal to or smaller than a predetermined value, to thereby determine light emission intensity for the recording of information.