Patent ID: 7933173

Claim:
A wobble signal extraction circuit, comprising: a radio-frequency signal component acquiring portion configured to acquire a radio-frequency signal component from at least one of a first signal and a second signal received by two light receiving portions, respectively, said two light receiving portions being obtained through division in halves with a direction along which each track of an optical recording medium extends as a boundary; a wobble signal acquiring portion configured to acquire a wobble signal by subtracting the second signal from the first signal; a radio-frequency signal component binarizing portion configured to binarize the radio-frequency signal component; a wobble signal binarizing portion configured to binarize the wobble signal; and an exclusive OR arithmetically operating portion configured to arithmetically operate an exclusive OR of the binarized radio-frequency signal component and the binarized wobble signal; wherein balances between an amplitude of the first signal and an amplitude of the second signal are detected based on an arithmetic operation result obtained in said exclusive OR arithmetically operating portion.