Patent GB-1067492-A (GB)
Title: Tensioning means and feeding means for magnetic tapes
IPC: G11B15/66
Filed: 1963-10-28
Abstract: 1,067,492. Magnetic recording and playback apparatus. MINNESOTA MINING & MANUFACTURING CO. Oct. 28, 1963 [Nov. 6, 1962], No. 42380/63. Heading G5R. A tape-advancing mechanism having a transducer head and means for drawing tape across the head from a supply, is characterized by the provision of pads on each side of the tape between the head and the supply, each pad having a resilient low-friction surface, and means for biasing the pads towards each other with the tape between them to provide a uniform back tension in the tape as it is drawn across the head. The mechanism may be used in recording/playback apparatus of the type including a changer mechanism (not shown), adapted to accommodate a stack of cartridges, such as 12 (Fig. 3), and to position a single cartridge in an operative position. The tape wound on a spool in the cartridge is provided with a stiff leader portion having a portion of greater width and with a stiff trailer portion at respective ends of the operative part of the tape. When a start button (not shown) is pressed, a drive roller 24 is moved into engagement with the reel flange 16 in the cartridge 12 to drive the leader portion 18 of the tape through a pair of open jaws 100 and 101, between guide pins 71, and past a capstan 11 to the take-up reel 27, the tape passing through grooves in upper and lower guide plates 56 and 57. After three increments of rotation of a cam-shaft 26 the roller 24 is withdrawn to the position shown, a pressure roller 45 is brought into engagement with the tape, and a lever 72 carrying the guide pins 71 is freed for clockwise rotation under the influence of a spring 78. If the leader portion is still within the grooves in guide plates 56 and 57 the lever 72 is restrained from moving, either by the stiffness of the leader portion or by the engagement of the wider front part of the leader portion with the grooves, and the tape is then driven by the capstan until the leader portion is wound on to the reel 27. When the lever 72 moves, the tape is drawn into engagement with erase and record/ playback heads 62 and 61 and a lever 64 moves to press the tape between a pair of felt pads 69 and 66 which provide back tension and also serve to clean the tape. Movement of the lever 72 operates a switch 80 which causes the camshaft 26 to rotate another increment to the " play " position, and energizes the amplifier and enables a counter (not shown) to begin counting take-up reel rotations. At the end of a tape the stiff trailer portion becomes taut between the capstan and the supply reel and moves lever 72 against its spring. This movement operates a further switch (not shown in Fig. 3) which causes rotation of the cam-shaft 26, thereby causing the lever 72 to be locked by member 98, the pressure roller 45 to be disengaged, and movement of the drive roller 24 into engagement with the reel flange 16 to drive it in the re-winding sense. At the end of the re-wind, the wide portion of the leader portion 18 of the tape engages the closed jaws 100 and 101 thereby moving member 98 and releasing the lever 72, and when the leader is clear of pins 71 the lever 72 moves and actuates switch 80 causing the cam-shaft to move another increment. This stops the re-winding and initiates operation of the changer mechanism. Manually-operated means may be provided for stopping and resuming playback and for initiating re-winding when desired.