Patent ID: 6339565
Filing Date: 2002-01-15
Classification: G11B

Abstract:
A sledge-center-error generating circuit comprising:photodiode inputs, receiving photodiodes' detected signals which is a light beam reflected from a data layer of an optical disk; a first summer, receiving a first pair of signals from the photodiode inputs, for generating a first sum signal; a second summer, receiving a second pair of signals from the photodiode inputs, for generating a second sum signal; a first subtractor, receiving the first sum signal and the second sum signal, for generating an overall error signal as a difference of the first sum signal and the second sum signal; a high-pass filter, receiving the overall error signal from the first subtractor, for generating a high-frequency error signal; and a second subtractor, receiving the overall error signal and the high-frequency error signal, for generating a low-frequency error signal by non-linearly suppressing the high-frequency error signal from the overall error signal; wherein the low-frequency error signal represents a sledge-center error, the low-frequency error signal for adjusting a position of a sledge containing the photodiodes, whereby the sledge-center error is generated by suppressing the high-frequency error signal.