| 摘要 |
PURPOSE:To obtain a picture with high quality by supporting other end of a bimorph fitted with a reproducing head at its free end in the canti-lever supporting mode to the tip of an arm, and displacing alternately the free end of the bimorph at each revolution to switch a track, thereby setting this displacement and the rotating position of the arm. CONSTITUTION:A driving voltage of the bimorph 11 is set so that the reproducing head 6 is displaced with a value smaller than a track pitch. When an output of a window comparator 43 goes to L because of the difference of a reproducing signal on tracks 3 and 4 and a latch pulse 45 is outputted, a differential information output 46 goes also to L. A CW direction rotating command signal 18 is outputted at the same time in this case and the arm 15 is displaced, although the difference of reproducing signals is decreased, the output of the comparator 43 is unchanged. When the displacement of the arm is progressed further and signals 18, 45 are outputted, the amplitudes of the reproducing signals 9 on both the tracks are made almost coincident with each other, the output of the comparator 43 is changed to H, the differential information output 46 is changed into H by the output of the pulse 45 and the signal 18, then a CCW direction rotation command signal 19 is outputted so as to restore the arm 15, allowing to make the center of the reproducing head 6 and both the tracks 3, 4 coincident with each other. |
