Patent ID: 7787341

Claim:
An optical disk device configured so that at least a first DVD optical disk or a second DVD optical disk is installed into the optical disk device, the second DVD optical disk having a smaller track width than the first DVD optical disk, the optical disk device comprising: a motor which rotates the installed optical disk; a pickup head which irradiates the optical disk with first DVD laser beam or second DVD laser beam through an objective lens to receive reflected light from the optical disk; a moving mechanism which moves the pickup head in a radial direction of the optical disk; a head amplifier which receives the reflected light from the pickup head to output at least a focus error signal, a tracking error signal, and an addition signal; a driving mechanism which uses the focus error signal and the tracking error signal to drive the pickup head to perform focus ON control and track positioning control; and a controller which controls the motor, the pickup head, the moving mechanism, the head amplifier, and the driving mechanism, the controller determining a first measured value as an average value of a plurality of amplitude values of the tracking error signal output by the head amplifier while the optical disk makes at least one rotation when the pickup head irradiates a system lead-in area of the rotating optical disk with the first DVD laser beam, or as a value obtained by normalizing the average value, the controller shifting the objective lens of the pickup head to the data area of the optical disk, the controller determining a second measured value as an average value of a plurality of amplitude values of the tracking error signal output by the head amplifier while the optical disk makes at least one rotation when a data area of the optical disk is irradiated with the first DVD laser beam, or as a value obtained by normalizing the average value, the controller determining an evaluation value by subtracting the second measured value from the first measured value, the controller comparing the evaluation value with a prescribed reference value, and the controller determining that the installed optical disk is the first DVD optical disk if the evaluation value is smaller than the reference value, and determining that the installed optical disk is the second DVD optical disk if the evaluation value is larger than the reference value.