Patent GB-817404-A (GB)
Title: Improvements in or relating to magnetic recording and/or reproducing machines
Inventor: ARMSTEAD WALTER EDWARD
IPC: G11B15/44
Filed: 1956-10-05
Abstract: 817,404. Driving sound film or tape. M.S.S. RECORDING CO. Ltd. Oct. 4, 1957 [Oct. 5. 1956; July 15, 1957], Nos. 30431/56 and 22423/57. Class 40 (2). A tape driving mechanism comprises a single reversible motor frictionally driving two intermediate wheels which are mounted on a pivoted support so that in one position a first intermediate wheel drives a flywheel associated with the tape driving capstan and the second intermediate wheel drives the take-up reel support and in an alternative position the second intermediate wheel drives the flywheel in a reverse direction and the first intermediate wheel drives the reel now acting as the take-up reel. A base plate 1 (Fig. 1) carries a motor on the shaft of which is mounted a wheel 25 which drives the two intermediate wheels 4 one of which drives the flywheel 5 and the other drives a reel support 2 through a slipping drive comprising a felt ring between the underside of the wheel 28 and the upper surface of the wheel 27 which is in edge contact with the intermediate wheel 4 and is free to rotate on the reel support shaft. The capstan 6 formed by the shaft of the flywheel projects through a plate 7 on which are mounted the magnetic heads 10 and 11. A three-position knob 12 mounted on a shaft 13 operates a switch controlling the direction of rotation of the motor and mechanically connects one or other of the intermediate wheels with the flywheel by rotating the link 16 coupled to a lever 17 which operates a slide 18 and moves a support 19, pivoted at 20, which has an extension 22 supporting a pair of arms 21, each of which carries an intermediate wheel 4. The slide 18 also actuates a linkage (Fig. 3) comprising a T-member 30 and a pair of bell cranks 31 to apply band brakes 32 to the reel supports when the knob 12 is in the central " OFF " position. Longitudinal movement of the slide 18 causes the T-member 30 to rock about the pivot 35 and rotate one of the bell cranks about its pivot 36. Whichever bell crank moves carries with it the other bell crank, by means of the co-operating lugs 37 on the cranks. The band brakes are thus released whenever the control 12 is moved to one of its operating positions. A second knob 14 has four positions, giving two capstan-controlled transducing speeds and a fast and a slow winding speed during which the capstan is inoperative. The knob is mounted on a shaft 39 which operates a switch to control the speed of the motor and also carries a plate 43 having a cam groove 42 engaged by a pin 41 fastened in a slide 44. Movement of the knob 14 from a transducing position to either the fast or slow wind position moves the slide 44 longitudinally and through the bell crank 45 also moves the slide 46 longitudinally so that the cam surfaces 47 lift the support 19 (Fig. 2) and hence the intermediate wheels 4 so that the drive to the reel supports is no longer through the slipping clutch but directly to the wheel. 28 An interlocking lever 48 (Fig. 3) is pivotally attached to the link 16 and engages a slide 49 through a link 50 only when a transducing position of the knob 14 has been selected, so that when the knob 12 is moved to an operative position the pressure roller 8 (Fig. 1) is urged towards the capstan 6 by the spring 9 and the appropriate felt pressure disc 53 is urged towards the head 10. Further interlocking means comprises a slide 54 (Fig. 3) having a V-shaped slot 55 which engages a pin 56 carried on the slide 18. When the knob 12 is in either of its operative positions the pin 56 moves the slide 54 into a position in which a pin 57 at its opposite end engages one of four grooves radiating from the circular groove 58 in the plate 43 and locks the knob 14 until the knob 12 is returned to the central " OFF " position. Two input circuit selector buttons 59 are provided and when depressed are locked by a plate 60 attached to the slide 54 (Fig. 5, not shown). The buttons automatically return to the up position when the knob 12 is moved to the " OFF " position. In a modification (Fig. 6, not shown) the two intermediate wheels are mounted on a plate pivoted on a pin parallel to the motor shaft. A friction clutch between the plate and the motor shaft turns the plate through part of a revolution each time the motor is reversed and effects the displacement of the intermediate wheels necessary to reverse the direction of the tape.