Patent ID: 6192010
Filing Date: 2001-02-20
Classification: G11B

Abstract:
An apparatus for use on an pickup head of an optical disc drive to adjust the pickup head to an optimal focus point, which comprises:means for generating a focusing error signal and an RF signal indicative of current focus point of the pickup head;a RFRP circuit, coupled to receive the RF signal, for generating a RFRP signal indicative of the difference between the maximum amplitude and minimum amplitude of the RF signal;a signal processor, coupled to said RFRP circuit, for detecting the amplitude of the RFRP signal; anda level bias circuit, coupled to said signal processor, for generating a predetermined number of focus bias points, with each neighboring pair of said focus bias points being separated by a predetermined bias, said level bias circuit carries out a procedure that includes sending said focus bias points in a successive manner to said means for generating the focusing error signal and the RF signal thereby to allow said signal processor to find the focus bias point which has the maximum RFRP signal and then using the focus bias point to replace the previous one, which procedure is repeatedly performed until the optimal focus point is found, at which status said level bias circuit is no longer able to generate the predetermined number of the focus bias points.