| 摘要 |
PURPOSE:To realize tracking control with high accuracy by detecting optically and continuously the revolving height position of a rotary magnetic head with no contact and in real time via an optical path for measurement which passes through the revolving center of a rotary head. CONSTITUTION:A bimorph plate 14 contains a reflector 15 to which the light of measurement is irradiated from a light source 20 through an optical path formed to a rotary shaft at the revolving center of a rotary magnetic head 13. A photoelectric converter 23 which detects the light of measurement reflected by the reflector 15 obtains a detection output containing a frequency component signal corresponding to microvibrations when the reflector 15 have microvibrations together with the head 13 with the drive of the plate 14. The detection output thus obtained is supplied to a phase wave detecting circuit 32. The mechanical displacement of the head 13 set to the plate 14 is detected in real time, and the tracking control is carried out for the head 13. In such a way, the overall tracking errors of the plate 14 are compensated to ensure the tracking control with high accuracy. |
