Patent ID: 7990824
Filing Date: 2011-08-02
Classification: G11B

Abstract:
1. A method for distinguishing unbalanced disc in an optical disc reproducing/recording apparatus, comprising following steps: moving an optical pickup head to a first position of an optical disc; rotating the optical disc to a predetermined rotating speed; transferring a focus error signal produced by the optical pickup head to a focus control voltage signal; controlling the optical pickup head by the focus control voltage signal to maintain a focus light spot produced by the optical pickup head on the optical disc; and distinguishing if the optical disc is an unbalanced disc according to the focus control voltage signal, wherein the focus control voltage signal passes through a low-pass filter and the frequency bandwidth of the low-pass filter has a proportional relation to the rotating speed of the optical disc, wherein the proportional relation is the value of the rotating speed divided by the frequency bandwidth equals to sixty.