| 摘要 |
PURPOSE:To enable high-density recording by obtaining an information signal from a track error. CONSTITUTION:Bits 4b-4d among bits 4a-4d are disposed to shift from guide grooves 2 and the bits on a medium 1 are detected by a pickup 5. The output therefrom is inputted to a circuit 15 for detecting a bit signal, a circuit 16 for detecting a track error signal and a circuit 17 for calculating a focusing error signal. A sample and hold (SH) circuit subjects the track error signal in the position having the bit to SH by the output from the circuit 16 and tracks the optical axis of an objective lens 9 to the central position of the bits via a track driving circuit 19. The SH circuit 23 adds the information signal (d) obtd. from the track error signal to the bit signal (e) from the circuit 15 in an adder 25 by which the information from the bits 4a-4d is obtd. The added output is inputted via a switch 24 to the circuit 19. High-density recording is thus made possible. |
