APPARATUS FOR GENERATING SEEK DIRECTION DETECTION SIGNAL FOR OPTICAL PICKUP

摘要

PURPOSE: An apparatus for generating a seek direction detection signal for optical backup is provided to output a seek direction detection signal by using main beam and sub-beam. CONSTITUTION: The first signal processing portion detects a track error signal by adding up and amplifying signals output from the first optical detector. The second signal processing portion(80) generates a seek direction detection signal by using signals output from the second optical detector. The second signal processing portion(80) comprises the first to the fourth adders(81,82,84,85), the first and the second differential portion(83,86), a gain controller(87), and the fifth adder(89) to obtain a track cross signal. The first adder(81) outputs a signal S3 by adding a signal SA2 to a signal SD2. The second adder(82) outputs a signal S4 by adding a signal SB2 to a signal SC2. The third adder(84) outputs a signal S5 by adding a signal SA1 to a signal SD1. The fourth adder(85) outputs a signal S6 by adding a signal SB1 to a signal SC1. The first differential device(83) outputs a signal S7 by using the signals S3 and S4. The second differential device(86) outputs a signal S8 by using the signals S5 and S6. The gain controller(87) outputs a signal K4*S8 by adding a predetermined gain rate K4 to the signal S8. The fifth adder(89) outputs the track cross signal by adding the signal S7 to the signal K4*S8.