Tracking servo circuit of optical disc player

Abstract

Abstract PURPOSE:To apply accurate tracking servo at all times by subtracting two sums of photodetector pieces arranged on diagonal lines of a 4-split photodetector and using a tracking error signal for the result multiplying a differentiating value of total output of each photodetector piece to an output from the subtraction. CONSTITUTION:Outputs a, c of the 1st and 3rd diodes 16a, 16c are added by the 1st adder 17 and outputs b, d of the 2nd and 4th diodes 16b, 16d are added by the 2nd adder 18. The operation of (a+c)-(b+d) is executed by a subtractor 19 and the operation of (a+b+c+d) is executed by the 3rd adder 20. The result of differentiation of (a+b+c+d) and (a+c)-(b+c) are multiplied by a multiplier 22. Thus, an outut of the multiplier 22 is supplied to a phase compensating circuit 23 and an output of the phase compensating circuit 23 performs the tracking servo for a tracking actuator 24.

Inventors

• 👤 Haruhide Okumura
• 👤 奥村　晴英

Bibliographic Details