Optical disc apparatus, control device and control signal generation circuit

Abstract

The optical disc apparatus comprises a convergence lens, a light detection devicefor outputting a first and a second detection signals after detecting reflected optical beam area by area, an actuatorfor shifting the convergence lens, a gain balance circuitfor changing a gain balance of the first and the second detection signals, an addition circuitfor outputting the addition signal AS after adding the first detection signal to the second detection signal in response to the shift in lens position and the change in gain balance made by the gain balance circuitand the actuator, and an addition signal measurement unitand a gain balance adjustment unitoperable to obtain the addition signal AS from the addition circuit, specify the gain balance that equalizes the detection sensitivities in the respective areas of the light detection devicebased on the obtained result, and control the gain balance circuitthat realizes the determined gain balance.