Patent ID: 7623419

Claim:
A signal processing device comprising: a track cross cycle measurement unit for receiving a tracking error signal showing a degree of deviation of a playback unit for playing data recorded on a recording medium from a track formed on the recording medium, and measuring a track cross cycle that is a cycle with which the playback unit crosses the track, on the basis of the tracking error signal; an off-track signal detector for detecting an off-track signal indicating that the playback unit is off the track; an off-track duty measurement unit outputting an off-track duty signal on the basis of the off-track signal; a tracking driver for moving the playback unit for playing the data recorded on the recording medium in the direction of the radius of the recording medium; a sled driver for moving the playback unit; a sled controller for controlling said sled driver; a system controller, said system controller controlling the tracking driver and the sled driver, and measuring the off-track detection sensitivity while moving or vibrating the playback unit in the direction in which the playback unit crosses the track; wherein said track cross cycle measurement unit gives the measured track cross cycle to the tracking driver and the sled controller.