| 摘要 |
PURPOSE:To determine accurately the amount of shift in shifting a pickup by skipping over a recording track of a disc, by providing a mans for detecting the pickup shift amount based on a signal outputted from the pickup when an optical beam crosses sequentially a recording track. CONSTITUTION:The zero cross point of a tracking error signal generated when a spot crosses over a track is counted sequentially by the 1st and the 2nd counter circuits 38, 39 until they reach an equal set value, and the positive and the negative level signals are outputted during the respective count period to produce a kick pulse, then the positive level and negative levels of the kick pulse are set eqaully easily. Since the width of the kick pulse depends especially on the shift of the spot on the disc 11 actually, the system is not susceptible to the effect due to the dispersion in the mechanical property of the converging lens drive system and the temperature change and the optical beam is shifted accurately to the objective track at all times. |
