JPS6425321A - Optical storage device - Google Patents

Abstract

PURPOSE:To obtain a constant information recording quality by providing a writing instructing circuit to generate the writing reference signal of a prescribed pulse time and the writing signal of a prescribed pulse time from the rear end of a writing reference signal, detecting the ratio of a reflecting light level and a writing driving level, comparing it with a prescribed reference level and obtaining a writing control signal. CONSTITUTION:A writing instructing circuit 1 is composed of one-shot circuits 2 and 3 of time which is T1, a writing power control circuit 4 is composed of current supplying circuits 5 and 7 and an attenuator 6 and a reflecting light reproducing circuit 13 is composed of an amplifying circuit 14, an attenuator 15, a delaying line 16 of the time which is T1, a differential amplifying circuit 17, a sample and hold circuit 18 and a low pass filter 19. By generating a reference power smaller than the recording power and not to form a pit immediately before the recording power to execute the pit formation, detecting the pit formation from the difference between both at a reflecting light level from the medium and feeding back it to the recording power, the constant reproducing time signal amplitude can be always obtained without being influenced by the reflection factor change in the medium or a focus control dislocation.