Magnetic tape speed control system

Claim 1

A magnetic recording and reproducing system using a magnetic tape provided with a control track separately from data recording and reproducing tracks, said system comprising: a. a magnetic head including a recording magnetic circuit having a recording mangetic circuit gap and a reproducing magnetic circuit gap, said gaps being spaced from but close to each other, said magnetic head including a central core for contact with the magnetic tape and two U-shaped side cores each mounted on one side of said central core, said recording gap being formed between an end of one of said side cores and said central core, said reproducing gap being formed between an end of the other of said side cores and said central core; b. means for generating a recording signal having a polarity which is reversed alternatively to be positive and negative each time an input signal is applied to said generating means, said generating means sending the recording signal to said recording magnetic circuit which records the recording signal on the tape; c. means, including said reproducing magnetic circuit, for reproducing the recording signal recorded on the magnetic tape and for producing a peak detection signal each time a peak point of the reproduced signal is detected; d. masking means, connected to said generating means and to said reproducing means, for producing an output signal in response to the peak detection signal and for applying the output signal to said generating means as the input signal, the output signal being maintained at a constant level for a period until a voltage, induced in said reproducing magnetic circuit due to leakage magnetic flux produced by said recording magnetic circuit when the current therein is reversed in response to the input signal applied to said generating means, is substantially reduced to zero; e. means, connected to said masking means, for detecting the time interval between one output signal of said masking means and the next output signal of said masking means and for producing a tape speed signal from the detected time interval, a voltage level of the tape speed signal being dependent on the speed of the tape; and f. means, connected to said detecting means, for driving the magnetic tape, said driving means including a supply reel and a take-up reel respectively coupled directly to drive shafts of drive motors, the speed of the magnetic tape being maintained at a predetermined level by controlling said drive motors in accordance with tape speed signal.