Patent attributes
An optical disc device for changing intensities of light beams illuminated on an optical disc. The optical disc device comprises the following elements. A photo detecting device divided into a plurality of photo detectors is used for detecting the reflected light beams illuminated on an optical disc. A plurality of amplifiers is used for changing gains to respectively amplify the output signals of the photo detectors when recording and reproducing on/from the optical disc. A calculating device is used for calculating the output signals of the amplifiers to generate the servo signals. By adding the correction offset signals for correcting the offset voltages of the amplifiers and the photo detectors to the amplifiers, the correction offset signals are amplified. It is, therefore, not necessary to change the correction offset voltages even though the gain of the amplifier is changed and not necessary to change the offset voltage and is independent of the gain-switching of the amplifier.
