Patent ID: 6611485
Filing Date: 2003-08-26
Classification: G11B

Abstract:
An asymmetry correcting apparatus in an optical disk reproduction system, for correcting the asymmetry of an analog signal output from an optical diode and outputting the asymmetry corrected signal as a digital signal, comprising:a first envelope detector for detecting an upper envelope of the analog signal; a second envelope detector for detecting a lower envelope of the analog signal; a level controller for controlling the level of the sum of the upper envelope and the lower envelope and outputting a first reference signal having a level equal to the level-controlled sum; a first low pass filter for filtering out a high frequency component of the first reference signal and outputting the filtered result; a second low pass filter for filtering out a high frequency component of the digital signal and outputting the filtered result; an amplifier for amplifying a signal output from the second low pass filter by a predetermined amount and outputting the amplification result; a subtracter for subtracting the output of the first low pass filter from the amplifier and outputting the subtraction result; an adder for adding the output of the subtracter to the first reference signal and outputting the addition result; and a comparator for comparing the output of the adder received as a second reference signal, with the analog signal and outputting the comparison result as the digital signal.