Tracking error detector employing phase difference detection met

Details Tracking error detector employing phase difference detection met Tracking error detector employing phase difference detection met

1997-09-26

1999-08-17

Westin, Edward P.

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

2502015, 369 4432, 369 4441, G11B 700

Patent

active

059397144

ABSTRACT:
A tracking error detector employing a phase difference detection method, comprising a photo detector for generating four divided signals, a first adder for adding two of the four divided signals from the photo detector, a second adder for adding the remaining two signals from the photo detector, first and second comparators for comparing output voltages from the first and second adders with a reference voltage, respectively, a first D flip-flop for providing first and second output signals synchronously with first and second output signals from the first comparator, a first OR gate for ORing the first and second output signals from the first D flip-flop, a second D flip-flop for providing first and second output signals synchronously with first and second output signals from the second comparator, a second OR gate for ORing the first and second output signals from the second D flip-flop, a third OR gate for ORing output signals from the first and second OR gates, a buffer for transferring the output signal from the first OR gate to its output terminal in response to an output signal from the third OR gate, an integrator for integrating a voltage signal from the buffer, a first switch being turned on in response to a DVD selection signal, and a second switch being turned on in response to a CD selection signal.

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patent: 5859816 (1999-01-01), Yamamoto

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