Patent ID: 6888783

Claim:
A wobble detection circuit, comprising: an optical system having a plurality of photodetector (light receiving) elements corresponding to several kinds of media having different pre-formats, the optical system receiving reflectional light from a medium at the photodetector elements, each of the photodetector elements being divided at least into two parts by a line tangential to a track formed on the medium; a selector selecting a set of outputs to be used from sets of outputs of the plurality of photodetector elements; a subtracting amplifier obtaining a difference signal between the set of outputs selected by the selector; a second amplifier changing a gain of an output of the subtracting amplifier depending on the pre-format of a reproducing or recording medium; and a binary circuit converting an output of the second amplifier into a digital signal; wherein the selection of the set of outputs from sets of outputs of the plurality of photodetector elements depends on the pre-format of a reproducing or recording medium.