Patent ID: 7724625

Claim:
An optical disk apparatus comprising: a laser beam source; a driving circuit which drives said laser beam source which irradiates a laser beam onto an optical disk; an irradiation beam photo detector which produces an amount-of-irradiation-beam detection signal in accordance with an amount of said laser beam irradiated from said laser-beam source; a reflection beam photo detector which produces an amount-of-reflection-beam detection signal in accordance with the amount of laser beam reflected from the optical disk; a period detector which detects whether a period during which a voltage of the amount-of-irradiation-beam detection signal is larger than a predetermined value is shorter than a predetermined period; a beam splitter which directs the laser beam irradiated from said laser beam source onto the optical disk and directs the laser beam reflected from the optical disk to said reflection beam photo detector, wherein, when said period detector detects that that the period during which the voltage of the amount-of-irradiation-beam detection signal is larger than the predetermined value is shorter than the predetermined period, then said laser beam source is being driven by said drive circuit.