Magnetic tape recording and reproducing apparatus using a small cycle time endless tape with movable head for replay

Claim 1

A magnetic tape recording and reproducing apparatus comprising: an endless magnetic tape of little re-cycle time; a tape driving means for drivingly transporting the magnetic tape; a magnetic head provided so as to contact the tape and movable transversely of the width of the tape, said magnetic head including first and second transduce or pick-up elements vertically disposed at a distance half of the width of the tape, and first and erasing elements; a a recording and reproducing circuit for applying a recording signal to the first and second transduce or pick-up elements and the erasing signal to the first and second erasing elements and for converting the output signal of the first and second transduce or pick-up elements into an audible signal; a changing switch for selectively changing over the recording and reproducing circuit to the recording condition or the reproducing condition; a rotary cam for vertically moving the magnetic head transversely of the width of the tape, said cam having a cam surface of gentle slope, said magnetic head being vertically moved in succession under influence of said cam surface when the cam is rotated through a turn; a first cam driving means for continuously rotating the cam as the tape is transported and for rotating the cam through a predetermined angle when the tape makes one cycle, said first cam driving means being connected to the tape driving means and operated in relation to operation of the tape driving means; a second cam driving means for steppedly rotating the cam in the direction opposite to the direction that said cam is rotated by the first cam driving means, said second cam driving means including a solenoid with a plunger reciprocable when the solenoid is energized, and a control switch for controlling the current supply to the solenoid, whenever said solenoid is energized in relation to operation of said control switch the cam being stepped rotated in relation to reciprocal movement of the plunger by the angle corresponding to the predetermined angle that the cam is rotated by the first cam driving means when the tape makes one cycle, the changing switch being adapted to be changed from the recording condition to the reproducing condition in response to operation of said second cam driving means; a rotary switch for selectively connecting the first transduce or pick-up element of the magnetic head to the recording and reproducing circuit during a half turn of the cam or connecting the second transduce or pick-up element of the magnetic head to the recording and reproducing circuit during from a half turn to one turn of the cam, said rotary switch being adapted to be operated in relation to rotation of the cam; a spiral recording track being formed on the half portion of the tape by the first transduce or pick-up element during a half turn of the cam when the changing switch is in the recording condition while another spiral recording track being formed on the remainder of the tape by the second transduce or pick-up element during another half turn of the cam, the control switch being controlled to operate the second driving means so that the changing switch is changed to the reproducing condition to move the magnetic head reversedly by one step whereby the tape is reproduced upon retroactively going back for one cycle time, the second cam driving means being operated in a plurality of times by the control switch so that the magnetic head is reversedly moved by the steps corresponding to those times when the tape is reproduced upon retroactively going back for the period corresponding to the product of one cycle time of the tape and those times.