| 摘要 |
PURPOSE:To make the automatic adjustment of azimuth angle possible by supplying a signal having a certain frequency to an electromechanical transducing element of a magnetic head to apply with angle modulation, and detecting azimuth angle error information on a basis of the state of the angle modulation component of a reproduced output and supplying in angle correcting signal to the transducing element. CONSTITUTION:The oscillation output of 10Hz from an oscillator 23 is supplied to a piezoelectric element 11, and a gap angle G is changed in accordance with its sine wave signal. A reproduced signal is subjected to envelope detection, and the center frequency passes through a BPF 29 of 10Hz, and it is subjected to sample holding and is superposed to the output of 10Hz from the oscillator 23. When the azimuth angle error is theta0, +theta, or -theta, the reproduced output is N1, N2, or N3 for the angle modulation input, respectively. They are subjected to envelope detection to obtain waveforms n1, n2, and n3. The BPF 29 extracts only waveforms n2 and n3. The phase shift quantity of a phase shifter 33 is so adjusted that the phase of an output S4 coincides with the phase of a maximum value of S29, and the maximum value of S29 is outputted from a sampling and holding circuit 30. This voltage is superposed as angle error information onto the sine wave of 10Hz and is applied to the piezoelectric element 11. |
