Patent GB-542961-A (GB)
Title: Improvements in ribbon feeding mechanism for typewriting machines
IPC: B41J3/24
Filed: 1940-06-10
Abstract: 542,961. Ink-ribbon mechanism. ROYAL TYPEWRITER CO., Inc. June 10, 1940, No. 10102. Convention date, July 20, 1939. [Class 100 (iv)] A typewriter is provided with means for feeding a ribbon (for example a carbon ribbon for use in typing matter suitable for reproduction by a photo-offset process) comprising a feedroller and a winding-roller driven by the carriage-propelling motor, the winding- roller being arranged to tension the ribbon and being associated with a frictioncoupling for permitting slip to compensate for the increase in diameter of the ribbon-coil. In the mechanism shown in Figs. 1, 2, and 6, a carbon ribbon 43 is fed from a spool 39, the core 39<SP>5</SP> of the spool being mounted loosely on a core hub 39<SP>1</SP> which is clamped by a screw 39<SP>8</SP> between discs 39<SP>3</SP>, 39<SP>6</SP> on a bracket 40 secured to the typewriter framework A. The ribbon is tensioned by the gravity-drag of the spool on the disc 39<SP>3</SP>. The ribbon, after passing through the vibrator G, is led over a guide-roller 62 and a feed roller 60 to a winding- roller 73, these rollers being mounted on a frame 46 secured to the framework A. The winding-roller comprises a disc 108 and a hub 108a mounted loosely on a shaft 74, and a detachable disc 107 provided with a knob 75 carrying a spring 75b having a pin 75a for engaging a groove in a collar 74a on the shaft. The ribbon is wound on a core 109 which fits on the hub 108a and is coupled by a pin 110 to the disc 108. The feed-roller 60 co-operates with a pressure-roller 59 on a pivoted arm 66 connected to another pivoted arm 70 by an over-centre spring 68 arranged to hold the pressure-roller in either the on or off position. The feed-roller is geared to the carriage-propelling drum 5 by means of shafts 95, 91, 83, 80, 77 provided with bevel-wheels, the shaft 77 being provided also with a pinion 76 which engages a pinion 20 on the drum 5. The shafts 83, 91 are connected by a pawl 89 and ratchet-wheel 90 so arranged that ribbon-feed occurs only during letter-spacing movement of the carriage B. The shaft 74 of the winding-roller 73 is geared to the shaft 91 and drives the winding-roller by means of a slip-coupling comprising springs 102 secured to an adjustable disc 100 on the shaft and co-operating with a disc 98 on the winding-roller. The winding- roller is driven at the such a speed in relation to the feed-roller that the ribbon is tensioned regardless of the amount of ribbon on the winding-roller, the slip-coupling permitting of slip to compensate for increase in diameter of the coil of the ribbon. Reverse rotation of the winding-roller is prevented by a pawl 104. In a modification, the driving disc 100 of the winding-roller is driven at twice the speed of the feed-roller. When the ribbon has been wound off the delivery spool 39, the discs 107, 39<SP>6</SP> are detached to permit exchange of the delivery spool and winding- spool. During exchange, the delivery spool and winding-roller may be reversed to bring a different longitudinal zone of the ribbon into use. Feed of the ribbon can be stopped by depressing a sleeve 111 and thereby releasing the pawl 89 from the ratchetwheel 90. For this purpose, a finger-lever 128 is provided with a cam 125 co-operating with a bell-crank 121 which is connected by a link 120 to another bell-crank 114 having a pin 117 co-operating with a groove in the sleeve 111. To prevent feed of the ribbon during tabulating runs of the carriage; the tabulating-key lever 131 is connected by a link 135 and arm 134 to the bell-crank 121. The typewriter is provided also with means for feeding the ordinary ink ribbon comprising spool-spindles 7, 8 driven alternatively by gearing comprising a worm 16 on a shaft 17 which is raised or lowered automatically, or by a finger-lever 25 which co-operates also with a depressible cam-lever 28 for moving the worm into non-driving position. When the carbon ribbon is used, the ordinary ribbon spools are removed and the feed-mechanism therefor is locked in non- driving position by depressing a lever 35 having a notch for engaging a pin 32 on the lever 28. When the ordinary ribbon is used, the carbon ribbon is removed, and the lever 35 is raised to permit the worm to be moved into driving position.