Patent GB-673064-A (GB)
Title: Improvements in or relating to a ribbon feeding mechanism for typewriters
IPC: B41J33/516
Filed: 1948-06-17
Abstract: 673,064. Ink-ribbon mechanism. INTERNATIONAL BUSINESS MACHINES CORPORATION. June 17, 1948 [June 21, 1947], No. 16309/48. Class 100 (iv). A typewriter comprises a first mechanism for operating a character-printing mechanism, and a second, separate mechanism for operating a ribbon-feeding mechanism, the second mechanism being rendered effective for operation by a universal bar actuated by the first mechanism, and a common main power actuator being provided for actuating the said first and second mechanisms. When a key is depressed, an extension 10a, Fig. 1, of a rod 10 rocks anticlockwise an interposer 28 pivoted at 16d to a cam 26, and thereby rocks the cam clockwise to bring a serrated portion 26a into contact with a continuouslyrotated power roller 14. The roller 14 moves the cam, which is pivoted at 16b to a lever 16, clockwise to raise the lever 16 and actuate a type-bar 15. Before the type reaches the printing-point, the movement of the -cam 26 is arrested by its nose 16f striking an adjustable spring prong 30a, and the remainder of the type-bar stroke is effected by inertia. The lever 16 pivots on the end of an adjustable bar 17. While the key is held depressed, the extension 10a abuts the left end of a lug 28b on the interposer 28 to prevent repetition, and when the key is released a spring 29 returns the interposer to its initial position. Similar mechanism is provided for each key, and when any type-bar is actuated, a nose 16g of the corresponding lever 16 rocks anticlockwise a universal bar 33 pivoted on a shaft 32 pivoted on the machine frame. When the universal bar 33 is rocked, a link 36, Fig. 2, is actuated to rock a trip lever 34g pivoted at 34e to a frame 34 pivoted at 35a to a fixed frame member 35, and thereby move a lug 34h out of engagement with a lug 34i on an elliptical cam 34a, whereupon a spring-actuated lever 34d acts on one of two lugs 34c on the cam to rotate the cam clockwise until a second lug 34i thereon abuts a lug 34j on the lever 34g. The cam is thus moved into engagement with a tread 14a on the roller 14, whereby the cam is rotated clockwise and the frame 34 is also rocked clockwise, whereby a link 37 is actuated to rock arms 32a secured to the shaft 32. When the arms 32a are rocked, two links 38 are raised, one for each ribbon spool, that for the left-hand spool 40 being shown, to rock clockwise a lever 45 and reciprocate a pawl 47a to the left. When the spool 40 is being unwound, the pawl 47a is held out of engagement with the spool ratchet 40a by a lug 51c on a lever 51. When the spool is unwound, the ribbon, being attached thereto, is tensioned and rocks anticlockwise a tension lever 54, through a slot in the end of which it is guided. The lever 54 is rocked against the action of a spring 55 and through a link 53 rocks clockwise an interposer 52 into the path of a lug 45b of the lever 45, whereby on the next oscillation of the lever 45, the lever 51, to which the interposer 52 is pivoted at 51b, is raised to allow a spring 48 to move the pawl 47a into engagement with the ratchet 40a. The lever 51 on moving upwards causes the equivalent lever for the other spool to move downwards, these levers being pivoted respectively to arms 60, 62 secured to opposite ends of a shaft 61. A dead-centre spring 63 acts to maintain the levers 51 in position. When the universal bar 33 is rocked anticlockwise, a link 72, Fig. 1, is actuated and through a lever 71 and link 70 tends to straighten a toggle 68, 69 and thereby raises through a lever 66 and link 67 the ribbon vibrator 25, which is thus raised at each actuation of a type-bar. According to the position of the lower pivot 73d of the toggle link 69, the vibrator is raised to one of four positions, the lowest being the stencil position and not high enough to reach printing position, the other three being for printing through a desired one of three zones of the ribbon. The pivot 73a is on a control lever 73b secured to a shaft 74 coaxial with the joint pivots of the toggle links 68, 69, and the position of the pivot 73a is altered by rocking the shaft 74 through a link mechanism by means of a control key. Noise on descent of the vibrator is minimised by a rubber or resilient synthetic plastic bumper 65d. The control lever 73b is held in the desired one of its four positions by means of notches 73c, 73d therein and lugs 73e, 73f thereon, which form in effect four recesses in one of which engages a roller 79a on a spring- actuated detent lever 79. Specification 660,263, is referred to.