| 摘要 |
In a DPP-type tracking error signal (TE signal), an offset caused by the difference between the reflectance of a main-beam irradiated part and the reflectance of side-beam irradiated parts is appropriately compensated without individual normalization of an MPP signal and an SPP signal. An analog signal processing unit 40 produces the MPP, MPI, SPP, and SPI signals on the basis of the amounts of received reflected light of the main beam and side beams detected by a photo-detection unit 130, produces a DPP-type TE signal and a CE signal on the basis of the MPP and/or SPP signal, and outputs the analog signals of the TE, CE, MPI, and SPI signals. A digital signal processing unit 50 computes the TE, CE, MPI, and SPI signals, which are converted into digital signals by an A/D conversion block 52, according to a predetermined arithmetic expression so as to produce a TE signal having an offset, which is derived from a variation in the reflectance of the main-beam irradiated part of the optical disk and/or the reflectance of the side-beam irradiated parts thereof, compensated.
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