| 摘要 |
PURPOSE:To always and accurately move a luminous flux on a groove or a land by holding a signal which is converted from a reflected light from an optical disk to an electric signal by a photodetector in an interval synchronized with a writing interval with large light quantity. CONSTITUTION:In a sample-and-hold circuit 109, the signal which is converted from the reflected beam from the optical disk 107 to the electric signal by the photodetector 108 is held during the interval synchronized with the writing interval with large light quantity by the signal from a recording pulse generating part 102 and sampled in other interval. The output of the sample-and-hold circuit 109 is inputted to a differential amplifier 110 subtracting the sum of the sample-and-hold circuit 2 and the sample-and-hold circuit 4 from the sum of the sample-and-hold circuit 2 and the sample-and-hold circuit 3. Then, the output of the differential amplifier 110 becomes a focus error signal. By a tracking error signal through a tracking control part 115 and a tracking driving part, current is made to flow through a tracking coil and the luminous flux is moved accurately on the groove by moving an objective lens 106. |
