OPTICAL DISK REPRODUCING DEVICE, AND A MIRROR SURFACE DETECTING METHOD OF AN OPTICAL DISK, PARTICULARLY CONCERNED WITH DECIDING WHETHER AN OPTICAL PICKUP IS LOCATED EITHER AN INFORMATION RECORDING AREA OR AN INFORMATION NON-RECORDING AREA WITHIN VERY SHORT TIME

摘要

PURPOSE: An optical disk reproducing device, and a mirror surface detecting method of an optical disk are provided to decide whether an optical pickup is located in either an information recording area or an information non-recording area of an optical disk, based on a level of a signal obtained from a reflected light, thereby deciding the position of the pickup before starting a reproduction process. CONSTITUTION: A signal level detecting circuit is assembled within a DSP(400). The signal level detecting circuit consists of a peak hold circuit(400a), a bottom hold circuit(400b), and a differential circuit(400c) to detect a peak-to-peak differential value of an RF signal as a level of the RF signal. A peak value is held by the peak hold circuit(400a), while a bottom value is held by the bottom hold circuit(400b). Differential values of the held values are obtained from the differential circuit(400c). The differential values are stored as differential data in a register(400d) to be read in a microcomputer(500). Based on the read data, if the differential values are small, the microcomputer(500) decides that an optical pickup is located on a mirror surface. If the values are large, the optical pickup is decided to be located in an information recording area.