Patent GB-842327-A (GB)
Title: Improvements in typewriters
IPC: B41J7/50
Filed: 1956-11-14
Abstract: 842,327. Typewriters &c. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 14, 1956 [Nov. 17, 1955], No. 34811/56. Class 100(4) Type wheel machines. A power-operated typewriter has a single element printing head which carries a plurality of characters and may be moved for character spacing and rocked for printing, all these movements being controlled by operation of a key lever and a flexible strand system, the path length of which is varied through cams and pulleys to change the characters in printing positions. To print a character, rocker 158, Fig. 2, carrying a type head 8 is rocked about 160 by a link 166, which itself is rocked about 168 by a cam 162. This latter is rotated by a square shaft 14, Figs. 2 and 4a, driven by 154, 152, 150 from a shaft 84. Printing pressure may be varied by adjusting the position of 168 in a slot 172. Key actions. A bail 34, Fig. 2, is depressed by an interposer 22, through 32, 30 and a key lever 16, to allow a shaft 36 to be turned one-third of a revolution by a pulley 52, Fig. 3, through a spring clutch. An ear 40, Fig. 2, of the shaft 36 pushes the interposer 22 to the left to rock up to seven of bails 44 each of which is connected to a clutch by a selector link 48, Fig. 3. A spring 70 disengages the interposer 22 from the shaft 36 when a gear 32 moves from under a projection 30 thus releasing a bail 34 which disconnects the drive from the shaft 36. One of the seven links 48-1, Fig. 4b, is moved by every key lever to trigger a one-revolution selecting clutch 76-78 whilst the other six links condition dog clutches 86, Fig. 4a, which determine the result produced by the selecting clutch. A dog 90 released by 98 engages a slot 94 in a shaft 84 so that a cam 88 rotates one revolution with shaft 84 when the selector clutch 76 engages. Cams 88 have follower arms 106 which carries pulleys 112 which change the path length of the selector wires Figs. 4c, 4d. Pulley 118 is fixed, pulley 120 is rotatable and movable towards and away from pulley 118. A carriage 10 can move from left to right without movement of the pulley 120. Pulleys 112, Fig. 4c, move the pulley 120 in or out whilst the carriage 10 is stationary thus turning the printing head 8 through a pulley 124. Pulleys 146, 148, Fig. 4d similarly tilt the printing head 8 through a pulley 138. Ink ribbon mechanism. A cam 174, Fig. 13, revolves with a shaft 14 and allows a ribbon vibrator 180 pivoted at 182 to be lifted by a spring 179, the degree of lift being controlled by a manual colour stop 184. The ink ribbon is wound from spool 176 to 178 and back by pawls operated when a finger 187 driven from 174 through 189, 188 oscillates a plate 190. Letter spacing mechanism. An escapement pawl 208, Fig. 8, allows a wheel 204 urged by a spring 206 to turn one tooth at a time. Rotation of a pulley 196 moves the carriage 10 one letter space at a time through a wire 194. A pawl 208 is controlled through 212, 216, 218, 222 by a cam 224 on a selector shaft 84. Space key action. An Interposer 230 is moved to the left in Fig. 8 by a shaft 36 through 228 when a space bar 226 is pressed. A bell-crank 234 pushes 238 to the right to release an escapement pawl 208 through 216, 212. A back space pawl 240, Fig. 7, urged by a spring 246 is controlled by a key 270 through 248, 250, 254, 256, 258, 260, 264 and 266 driven through an interposer 268 by the shaft 36. Shift key actions. Upper case characters are selected by rotating the head 8 through 180 degrees by moving apart pawls 309, 310, Fig. 4c, through an interposer 280, Fig. 2b, 282,284, and a pawl 290 which actuates a spring clutch causing 302, 304, 306, Figs. 2d, 4b, to rotate. Each operation of a link 284 causes a shaft 304 and a cam 308 through 306 to turn half a revolution. The cam 308 and another similar one spread apart pulleys 309, 310. Key levers 272, 274, Fig. 2b control case shift and can be locked in upper case position. The interposer 280 is not restored to rest position until lower case is again selected. Tabulation key actions. Pins 442, Fig. 9, act as margin stops when moved up, tabulation stops when moved down and have no action in the central position. Depression of a lever 470 depresses an interposer 472 and a bail 34 causes the shaft 36 to rotate. A bell-crank 474 pulls 476 to rock 458 and pull 462 to unlatch the escapement pawl 208 and set the tabulation mechanism 446, 448. When a pin 442 hits 446 and 448 the mechanism is knocked back to its original position and the pawl 208 re-engages the escapement wheel 204. Carriage return mechanism. A pawl tape 322, Fig. 6 turns a hub 320 to return the printing head carriage and re-wind the escapement spring, clutch operating driving member 324 supplying the power. An interposer 330 triggered by 326 moves to the left and engages a clutch 354 through 332, 334, 336, 340, 346, 348. A plate 340 is held in actuated position by 342, 344 and released from it when a margin stop 356 engages a pin 358 and acts through 360, 362 to unlatch 342 from 344. Line spacing mechanism. A pawl 374, Fig. 5a turns a platen 364 through 368 when rocked by 380, 382, 390, 392, 394, 396 and 398 which is oscillated by an eccentric 402, Fig. 5b. Single, double and triple line spacing are provided. The eccentric 402 rotates when a dog 412 engages continuously rotating wheel 410, Fig. 5a. The dog 412 is controlled by a key 434 through 432, 430, 428, 426,416. Line spacing automatically occurs on completion of carriage return through 336, 436, 438. Platen guide rollers. The platen 364, Fig. 12, is locked in slots 500 by gears 502, 504. The paper feed rollers are moved out of engagement with the platen 364 by turning 490, a spring 522 holds them in contact. Specification 842,328 is referred to.