GB1098625A - Tape transport arrangement for tape recorder - Google Patents

Abstract

1,098,625. Eddy-current brakes; motor driving arrangements. EPSYLON RESEARCH DEVELOPMENT CO. Ltd. July 2, 1964, [Sept. 24, 1963], No. 37598/63. Heading H2A. [Also in Division G3] A tape transport arrangement for a magnetic tape recorder comprises a torque motor driving each spool, a magnetodynamic brake coupled to each spool and a tension sensing device, associated with each spool, responsive to tension in the portion of tape between that spool and a capstan controlling the braking torque to offset changes in tape tension. As shown, a magnetic tape 13 is withdrawn from a reel 11 and passed over a reading head 17 by a constant speed capstan having a cooperating pinch roller 19, the tape being taken up by a reel 12. The tension on the tape being fed past the head is detected by a loop of tape 26, 27 passing over a guide roller 15 counter-balanced through a lever 23, 24 about a fulcrum 25 by a spring 28. Movement of the lever due to variation in tape tension causes a corresponding movement of a slider of a rheostat 30 to vary the input to an amplifier 31, the output of which varies the excitation of an eddy-current brake so as to tend to maintain the tape tension constant. A similar arrangement is employed for the take-up from the capstan. The reels 11, 12 are driven by motors having a fixed inner part and a rotating outer part, equivalent to the stator, to which a friction brake is applied. The eddy-current brake comprises a ferromagnetic ring having an annular groove, containing an excitation winding, which is concentric with a spindle. The spindle drives a tape reel and carries an aluminium or copper disc which rotates in an air gap between projecting parts of the ring and an end-plate.