Patent ID: 8259548

Claim:
An optical disc device, comprising: a light source driven by a drive signal with a high frequency signal superimposed; a detector for detecting return light emitted from the light source; and a controller for controlling the amplitude of the high frequency signal to be superimposed on the drive signal, the optical disc device being configured to read data from an optical disc loaded therein by a signal outputted from the detector, wherein: the controller causes the light source to irradiate the loaded optical disc with light in a condition in which a high frequency signal different from a high frequency signal for data reading is superimposed on the drive signal; the controller identifies a type of the loaded optical disc based on the return light from the loaded optical disc detected by the detector; the controller measures a first asymmetry from an output of the detector without a high frequency signal superimposed on the drive signal; and the controller identifies the type of the loaded optical disc as either a writable disc or a read only disc based on a comparison result of the measured first asymmetry with a predetermined threshold.