Patent GB-1011875-A (GB)
Title: Ribbon feed mechanism in typewriters, computers and similar machines
IPC: B41J33/56
Filed: 1962-06-22
Abstract: 1,011,875. Ink-ribbon mechanism. SOC. DE MECANOGRAHIE JAPY. June 22, 1962 [Aug. 12, 1961], No. 24170/62. Heading B6F. Varying-throw type vibrator mechanism.- An ink-ribbon feed mechanism for maximum wear of textile, carbon-paper or carbon synthetic plastic ink ribbons 14, Fig. 1, which are displaced transversely after each typing operation, is provided with a driving lever 6 actuated by a universal bar 8, through a push-rod 7, to lift an ink-ribbon guide fork 1 from a normal position, in which the printed characters are visible, to successive elevated positions, Fig. 2 (or Fig. 5, not shown) corresponding to multiples of one character height and the mechanism is further so designed that the feed step of the ink ribbon in the longitudinal direction thereof, after each typing operation, amounts to a fraction of one character width. In one embodiment, in Fig. 3, in which the ribbon 14 is elevated to two different heights, Fig. 2, the ink ribbon guide fork 1, is lifted by a lever 2 on a shaft 3, having mounted thereon a variablethrow cam-plate 4, Figs. 1 and 3, provided with camming slots 23, 24 engaged by a pin 17 fast on the driving lever 6 mounted for pivotal moveon a shaft 16. On depression of a type lever clock-wise rotation of the lever 6 causes the pin 17 to travel along the camming slot 23, pivoting the cam-plate 4 about the shaft 3 and also displacing a pawl 25 by engagement with its upper cam surface 31, so that an arm 28 of the pawl resting against a stop 30 is caused to rest against a stop 29. Return movement of the pin 17 to its initial position displaces the arm resiliently without effectively changing the position of the pawl 25, which is arrested in that position by a spring 27, Figs. 3 and 11. Following depression of a further type lever causes the pin 17 to enter the camming slot 24 (Fig. 4, not shown) as the slot 23 is obscured by the arm 28 and the fork guide 1 is elevated to a second higher position. The pawl 25 is simultaneously re-set to rest against the stop 30 by the pin 17 engaging a lower cam surface 31. In another embodiment (Figs. 6 to 10, not shown) the twostage variable-throw cam-plate 4, may be replaced by a three-stage variable-throw camplate 35. The ink-ribbon 14 is displaced in the longitudinal direction thereof by one half or one third of one character width. Adjustment for multi-colour work; rendering inoperative.-For two-colour work the carbonpaper ribbon 14 is replaced by a red-black textile ink ribbon and the lift of the fork guide 1, Fig. 1, is provided by a multi-colour selection cam-plate 5, Figs. 1 and 11, mounted in spaced relationship from the cam-plate 4 on the shaft 3 and to this end the shaft 16 is displaced against the action of spring 21 to thereby cause pin 18 on the lever 6 to engage a slot 60 in the camplate 5 for " black " typing operation. For " red " typing operation the lever 6 is brought into intimate contact with the cam-plate 5, Fig. 11, so that a surface 63 (Fig. 12, not shown) of the lever 6 engages with a bolt 62 on the camplate 5 to direct the pin 18 into engagement with a slot 61. For the purpose of cutting wax stencils, when no ink-ribbon is required the shaft 16 is displaced into an intermediate position as shown in chain-dotted lines in Fig. 11, and the ink ribbon guide fork 1 is rendered inoperative. Ink-ribbon feeding.-To control the ink ribbon feed at a constant rate and compensate for the varying diameter of the ink ribbon winding 70, Fig. 13, the ink ribbon spool 74, mounted on a shaft 85 and driven by gears 84, 81 is given variable incremental rotation. The incremental rotation is controlled by a sensing lever 71 having an arm 72 engaging the ribbon winding 70 and a coupling-rod 75 whose pin 76 is displaceable along slots 77 of a feed arm 78 connected to the gear 81 and slot 69 in a bell-crank lever 67 connected by links to the universal bar 8. In dependence on the diameter of the winding 70 the pin 76 is displaced in the slot 69 so that for a decreasing diameter of the winding the bell-crank lever 67 imparts a greater clockwise angular displacement to the feed arm 78, the uni-directional feed of the spool 74 being secured by two springs (not shown) acting as a frictional clutch.