Patent ID: 7280451

Claim:
A wobble signal detecting circuit for an optical disk reproducing device configured to reproduce an optical disk which has a track including a snaking portion at a specific period, the wobble signal detecting circuit comprising: an optical detecting unit which detects a signal written on the track; a first band-pass filter and a second band-pass filter, which have different pass bandwidths, and extract a first wobble frequency component of the snaking portion and a second wobble frequency component of the snaking portion, respectively, based on outputs from the optical detecting unit; and a wobble signal determining unit which compares the first wobble frequency component and the second wobble frequency component, to determine whether or not a wobble signal is present, wherein the wobble signal determining unit determines that a wobble signal is present if a frequency difference or a frequency ratio of the first wobble frequency component and the second wobble frequency component is equal to or less than a prescribed value, the first band-pass filter has a bandwidth, upper cutoff of frequency part of the bandwidth of which is located on a wobble frequency, the second band-pass filter has a bandwidth, lower cutoff of frequency part of bandwidth of which is located on the wobble frequency, and a part of the pass bandwidth of the first band-pass filter is overlapped with a part of the pass bandwidth of the second band-pass filter.