| 摘要 |
PURPOSE:To detect an amplitude variation of a cantilever with high sensitivity, to make an amplification degree of an amplifier low, and to execute stable tracking control operation without being affected by noises from the outside, by providing a light emitting element and two photodetectors on the same side by separating them from the cantilever. CONSTITUTION:From a disk 1 rotating in the direction A, a reproducing stylus 2 which has been attached to the tip of a cantilever 3 reads and reproduces a signal by executing control operation in the tracking direction B and the time base correcting direction C. A light emitting diode LED 9 is placed at a position which has been opposed and separated to and from the cantilever 3, and two pieces of photodetectors 10, 11 are arranged and provided in the tracking position at a position where light from the LED 9 is separated at the projecting part of the cantilever 3, reflected by the surface of the cantilever, and thereafter, the light quantity of the same extent returns. As for the providing position in the direction C of the LED 9 and the photodetectors 10, 11, they are provided in the vicinity of the tip because the nearer they are to the reproducing stylus, the more the amplitude sensitivity level of the tracking direction B increases. |
