Wobble signal detecting circuit, wobble abnormality detecting circuit,

Abstract

In a wobble signal detecting circuit provided by the present invention, a wobble signal is converted into binary data before being supplied to a PLL circuit by way of a polarity switching circuit and a clock switching circuit. The PLL circuit outputs a recording/playback timing generation clock signal. The frequency of the recording/playback timing generation clock signal is divided by a frequency dividing circuit before being fed back to the PLL circuit. A difference in phase between the wobble signal and the feedback signal is detected by a phase inversion detecting circuit and, if the difference in phase exceeds a phase difference determined in advance, the phase inversion detecting circuit generates a polarity switching signal for switching the polarity of the wobble signal. The polarity switching signal is used to invert the polarity of the polarity switching circuit.