Patent ID: 8098554

Claim:
An information recording and/or reproducing apparatus, comprising: an optical head for emitting a light beam on a medium and receiving a reflected light beam from the medium, a tilt is defined by a deviation of the angle of the light beam from the medium; an analog signal processor for processing the reflected light beam to obtain a first analog signal; an analog/digital converter for converting the first analog signal into a digital signal; a controller for applying a low-pass filtering operation on the digital signal to obtain a digital controlling signal; a digital/analog converter for converting the digital controlling signal into a second analog signal; and an adjustment mechanism for adjusting a position of the optical head to correct the tilt according to the second analog signal; wherein the controller comprises a first calculator for applying a first low-pass filtering operation on the digital signal, the first calculator performing a function of: C 1 ( z )=( K 1 *A ( z )+ K 2 )/( A ( z )− K 3 ) wherein C 1 (z) represents a signal which is outputted by the first calculator after applying the first low-pass filtering operation on the digital signal, A(z) is the digital signal which is a variable parameter and represents an input signal of the first calculator, K 1 , K 2 , and K 3 are constant parameters of the first calculator, and z represents a frequency of the first analog signal.