| 摘要 |
A wobble-signal detecting device detects a wobble signal based on a signal which is the difference between outputs of two divisions of a light receiving device. These two divisions are located on both sides of a line parallel to a target portion of an information recording track. This light receiving device receives light reflected by a recording medium as a result of an optical beam being incident on the recording medium. This recording medium contains the information recording track, which wobbles at a predetermined frequency, and has pre-pits formed at predetermined intervals in areas between the information recording tracks. This light receiving device comprises a pre-pit controlling portion which removes or reduces the pre-pit components of the signal which is the difference between the outputs of the two divisions of the light receiving device, and outputs a pre-pit-component-controlled signal; and a wobble-frequency-component extracting portion which extracts wobble-frequency components from the pre-pit-component-controlled signal and outputs a wobble-frequency-component signal, the wobble signal being obtained based on the wobble-frequency-component signal.
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