| 摘要 |
<p>PURPOSE:To reproduce a control signal stably even in an extremely low speed, by using a magnetic flux response type head in a VTR. CONSTITUTION:A magnetic flux response type element (MR head) 54 used as a control head 19 is arranged in correspondence with control signals 41-43 on a magnetic tape 20 to reproduce these signals. The MR head 54 is connected to a power source 51 through a bias resistance 52, and an electric signal corresponding to the resistance variation of the MR head 54 is inputted to a non-inverted input side 53 of an operational amplifier 55. An amplified reproduced control signal is obtained in an amplifier output 59. A low pass filter part 64 permits only low frequency drift components due to the temperature variance of the MR head to pass through and feeds back them negatively to the operational amplifier 55, and therefore, the low frequency drift is not inputted to a waveform shaping part 71, and the reproduced control signal very stable against the low frequency disturbance is obtained in the output 59. A reference voltage obtained by dividing the power source voltage and the reproduced control signal 59 are compared with each other in voltage to obtain the control signal converted into rectangular waves in an output 69.</p> |
