| 摘要 |
PURPOSE:To provide an optical disc memory in which tracking offset is eliminated it the time of operation and stability is enhanced at the time of recording/ reproduction. CONSTITUTION:A diffraction grating 22 is inserted between a prism 5 and a deflection beam split 4, a preceding beam spot A, a main beam spot B and a following beam spot C are then projected onto the surface of a disc memory medium 1, and light beams (a), (b), (c) and (a'), (b'), (c) reflected on a recording pit are detected, respectively, on the surfaces of photosensors 10, 12. Projection of beams is controlled such that the preceding beam spot A and the following beam spot C detect, respectively, the right and left ends of the recording pit on the surface of the disc recording medium 1 whereas the main beam spot B, sandwiched by the preceding and following beam spots A and C, impinges on the center of the recording pit at all times. |
