Patent GB-548580-A (GB)
Title: Improvements in ribbon mechanism for typewriting machines
IPC: B41J35/14
Filed: 1941-07-18
Abstract: 548,580. Ink-ribbon mechanism. ROYAL TYPEWRITER CO., Inc. July 18, 1941, No. 9132. Convention date, Sept. 30, 1940. [Class 100 (iv)] Means is provided for feeding a hectograph, or other ribbon along the printing line of a typewriter, and for applying tension after the line-spacing mechanism has been operated to feed the work-sheet. By these means, the ribbon is stretched after each linespacing operation, and typing is confined to a definite longitudinal zone so that, as described below, three such zones can be used in succession. In the mechanism shown in Figs. 1, 4, and 13, a hectograph ribbon 57 is fed from a spool 60 on the framework A and passes through tensioning and feeding devices E, F on the carriage B to a winding-spool 173 on the framework. The ribbon is arranged along the printing line on the platen C and behind the sheet 56 to be typed and is guided by rollers 70, 163, 167, 169 mounted on arms 71,164,166 on the framework, and a roller 91 mounted on the device E. The winding- spool 173 is driven from the carriage spring-drum 5, during letter-spacing movement of the carriage, in the manner described in Specification 542,961. The device E comprises a plate 75 which is mounted on pins 76, 77 on a bracket 73 on the carriage, and supports a slide 83. The ribbon is engaged by a roller 93 on the slide, and a roller 94 on a spring- urged bell-crank 97 pivoted on the slide and formed with a nose 108 for co-operation with a nose 107 on a dog 102 pivoted on the plate 75. The slide engages a pin 150 on a bell-cranK 14/ which is coupled by a link 145 to an arm 143 on a rock-shaft 142 having another arm 141 which has lost-motion engagement 140 with a link 136 connected to the line-spacing lever 4. The rollers 93, 94 are braked by springs 100, 101. On operation of the linespacing lever, the slide 83 is moved to the left, the nose 108 rides up the nose 107, and the roller 94 is disengaged from the roller 93. At the end of the movement, the dog permits the roller 94 to reengage, and latches the slide. The device F comprises ribbon-engaging rollers 109, 110 mounted on brackets 112, 118 on the carriage and line-spacing lever 4 respectively, engagement being maintained by the lever return-spring 122. When the carriage is letter-spaced, the rollers 10i9 110 are locked by pawls 115, 120 and feed the ribbon, tension being maintained by the rollers 93, 94, and the fed length being wound on the winding-spool 173. When the line-spacing lever is operated, the roller 110 is disengaged from the roller 109 and, during the linespacing movement of the platen, the slide 83 is moved to the left, and the roller 94, is disengaged from the roller 93. The rollers 94, 93 then reengage, and during return of the carriage, exert on the ribbon a pull in contra-feed direction, the pull being resisted by the spool 173. On release of the line-spacing lever, the rollers 110, 109 re-engage, the slide 83 is returned by the bell-crank 147 and a spring 88, and the rollers 93, 94 stretch the ribbon in preparation for typing a new line. Means is provided for preventing the ribbon from being fed when the carriage is moved after release from the escapement-mechanism 7 by the usual carriage-release levers or the tabulating-key 29. For this purpose, the feed-rack 10, when lifted, rocks arms 152, 157, the arm 152 having pin-and-slot engagement 155 with the link 136, and the arm 157 having an arm 159 which is connected by a link 161 to the bellcrank 97. On release of the carriage, the rollers 110 94 are disengaged from the rollers 110, 93, and the slide 83 is moved to the left. To prevent operation of the winding-spool 173 during tabulating, the tabulating-key is, as described in the above-mentioned Specification, coupled by linkage 234 to a rock-arm having a pin 238, Figs. 3 and 20 (not shown) for releasing a ratchet-coupling arranged in the train of gears between the spring drum 5 and the winding- spool. To prevent interference with the ribbon when the platen-knob is operated, the platen-knob 248 is arranged at a distance from the ribbon and is connected to an extension 40a of the platen-shaft by gearing 246. To provide for maximum wear of the ribbon, the plate 75 can be raised on the pins 76, 77 by means of a finger-peice 82, Fig. 13, and is provided with a spring finger which engages grooves 80, 81 in the pin 76 to hold the plate in normal or raised position. A ribbon-guide 124 can be raised on a part of the bracket 112 by means of a finger-piece and is retained in normal or raised position by co-operation of a spring-finger on the bracket with notches in the ribbon-guide. When a new ribbon is used, the plate 75 and guide 124 are set in normal position and the middle zone I, Fig. 13, is presented. When the zone is exhausted, the coiled ribbon is transposed from the spool 173 to the spool 60 without being inverted, the plate 75 and guide 124 are raised, and zone II is presented. When this zone is exhausted, the coiled ribbon is transposed to the spool 60 and inverted, and zone II is presented. The winding- spool gearing described in the above - menfioned Specification may be modified in the following manner:-The slipopening coupling for the spool 173 is replaced by a pawl 206, Fig. 1, and a wheel 210 having equiangular serrations. The ratchet-coupling in the train of gearing is replaced by a spring 200, Fig. 20 (not shown), and a co- I operating toothed wheel 194. The spring may be replaced by a toothed wheel 188b, Fig. 16 (not shown).