Patent ID: 7020061

Claim:
A system capable of preventing an over-current through a pick-up head of an optical storage device, comprising: a sample-and-square circuit for sampling a current through the pick-up head to obtain a root-mean-square value of the current; a computational circuit for receiving the root-mean-square value of the current and generating an output, a delay circuit for delaying the output from the computational circuit, and feeding back the delayed output to the computational circuit; and a threshold detection circuit for preventing the current flowing into the pick-up head when the output from the computational circuit during a sampling interval is greater than a threshold value, wherein the computational circuit generates the output according to the root-mean-square value of the current, a preset value and the delayed output from the delay circuit; the preset value in exponential type is related to an allowable current and a maximum current of the pick-up head.