Optical disk identification circuit

摘要

The present invention offers an optical disk determination circuit that can improve the stability of the operation to detect the peak (pulse signal) of the received light signal, and that can improve the stability of the optical disk determination operation. When determining the type of optical disk corresponding to the depth from the surface of the plane on which a light beam is irradiated to the data recording layer, light is irradiated while varying the focal position of the light beam at a constant velocity in one direction of the depth direction from the surface of the optical disk. The bottom level of the received light signal corresponding to the intensity of this reflected light is clamped at a specified level by the bottom clamp circuit 43 . The received light signal with the bottom level clamped is compared with a specified reference voltage Vref by the comparator 45 , and the received light signal peak (pulse signal) is detected corresponding to the results of this comparison. The type of optical disk is determined by measuring the difference in this peak (pulse signal) detection time.