| 摘要 |
PROBLEM TO BE SOLVED: To detect a tracking error so as not to cause an offset. SOLUTION: An optical pickup device 11 is provided with a beam generation part 21 generating a main beam MB detecting information recorded on a groove on a disk 17 and four pieces of sub-beams SB1 -SB4 detecting the out-of-track of the main beam MB, a photodetector 20 separately light receiving respective return light of the sub-beams irradiating the disk 17 from the beam generation part 21, comparing the intensities of the return light and detecting the out-of- track of the main beam MB and a tracking error signal generation circuit 22 comparing signals outputted from the photodetector 20 and generating a tracking error signal. The tracking error signal generation circuit 22 compares light intensities of respective sub-spots SS1 -SS4 to output the tracking error signal. |
