Patent ID: 7242643
Filing Date: 2007-07-10
Classification: G11B

Abstract:
1. An optical disk apparatus comprising: a tray means for carrying an optical disk in and out of the optical disk apparatus; a chucking means for chucking the optical disk; a laser irradiation means for emitting a laser beam that is focused on the optical disk, and for activating a focusing servo; a moving means for moving the laser irradiation means in a radial direction of the optical disk; a measurement means for, after the chucking means has chucked the optical disk, measuring focusing drive voltages for the focusing servo at a point near a center of the optical disk and at a point near an outer edge of the optical disk, without rotating the optical disk; and a control means for comparing, with a first reference value, a difference between the focusing drive voltages measured by the measurement means, and for, when the difference between the focusing drive voltages is greater than the first reference value, permitting the chucking means to release and again chuck the optical disk; wherein, in the case where the chucking means repeats the chucking of the optical disk, the measurement means, without rotating the optical disk, again measures the focusing drive voltages for the focusing servo at the point near the center of the optical disk and the point near the outer edge of the optical disk, and the control means compares, with the first reference value, the difference between the focusing drive voltages, and when the difference is greater than the first reference value, permits the chucking means to release the optical disk and the tray means to discharge the optical disk; in the case where the measurement means measures the focusing drive voltages while the laser irradiation means is moved between the point near the center of the optical disk and the point near the outer edge and the focusing servo is actuated, the control means compares, with a second reference value, a difference between the focusing drive voltages for the measurements made by the measurement means at two adjacent points, and when the difference between the focusing drive voltages is greater than the second reference value, permits the chucking means to release the optical disk and the tray means to discharge the optical disk; and in the both cases the measurement means measures focusing drive voltages while the moving means moves the laser irradiation means from the outer edge to the center.