Kabushiki Kaisha Toshiba

Satoshi Sakuma

Hayato Masubuchi

Toyokazu Eguchi

When a disc is driven at a low speed, the number of tracks crossed by a beam spot of an optical pickup (3) is determined as the number of crossing tracks corresponding to an amount of mass eccentricity of the disc. If this number of crossing tracks exceeds a first threshold value, the disc is rejected as a non-conforming disc. When the disc is driven at a high speed, the number of tracks crossed by the beam spot is determined, a value remaining by subtracting the number of crossing tracks at the low speed from the number of crossing tracks at the high speed is determined as an amount of vibration produced owing to a mass eccentricity of the disc. Thus, a disc drive which can make an extremely precise detection of a magnitude of vibration resulting from the mass eccentricity of the disc without using a sensor component for detecting the vibration can be provided.

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Yokohama, Japan

Satoshi Sakuma