Patent GB-748825-A (GB)
Title: Improvements in or relating to tabulator mechanism of a typewriter or like machine
IPC: A47K10/34
Filed: 1953-03-16
Abstract: 748,825. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. March 16, 1953 [May 8, 1952], No. 7173/53. Class 100 (4). Tabulating mechanisms, key action.-In a typewriter having a movable carriage and column stops mounted thereon or on the frame, a series of counter stops are provided and are selected and positioned by an appropriate key thereafter to be moved by an operating member into the path of the column stop. Column stops 40 of a rack 34, Figs. 2, 4, are set by a lever 44 and unset by a clearing cam lever 46 operated by keys through connection with a shaft 52. A bank of counter stops 112, Fig. 3, are mounted on a carriage comprising a support member 114 having slots 114a which are engaged by studs 136a of a frame member 136 attached to a resilient bracket 126 secured to a rail 22 of the main carriage support. Each stop 112 is pivotally mounted by a slot 112a, Fig. 4, on a shaft 118 of the counter stops carriage and has branches 112b, 112c and a lug 112d to which a spring 120 is attached to urge the stop 112 against the support 114 and the pin 118 against the top of the slot 114a. Two similarly constructed spacer elements 124, Fig. 5 (not shown) are provided in the position of the commas printed between certain denominational orders. A bail member 168 pivotally mounted on the shaft 118 is urged by a spring 174 to engage a projection 112e on the arm 112c of a selected stop except when held by an operating lever 170 which is in turn actuated by a power cam unit 172. The unit 172, Fig. 1, comprises a frame 180 pivoted on a stud 178 carrying shafts 180b, for a lobe cam 182, and 180c on which is an arm 184 biased by a torsion spring towards a pin 182a on the cam. A trip lever 186 having offset lugs 186a, 186b controls the operation by the lugs alternately engaging a pin 182c projecting from the cam 182 on the other side to the pin 182a. The denominational keys 142 are arranged in numerical sequence and on the depression of one selected the initial movement causes a stem 144 to engage a pin 148 of a bell crank lever 150 which acts through a link 156, bell crank 158, link 164 to position the selected stop 112 with the shaft 118 engaging the bottom of the slot 112a. Further depression of a key 142 causes an offset 144b of the stem, after the initial free movement allowed by a notch 144a which ensures prior positioning of a stop 112, to engage a prong of an actuating member 192 to rock the trip lever 186 through a link 200. The rocking of the trip lever 186 releases the offset lug 186a and the cam rotates sufficient to engage its tread surface 182d with a constantly rotating power roller 56 which rotates it one revolution and since the surface 182d is eccentric with the shaft 180b the latter is shifted away from the roller rocking the unit about the shaft 178 and by a link 190 moving the operating lever 170 which allows the operating member or bail 168, under the action of a spring 174 only, to engage the arm 112c of a selected stop to move it into the path of a column stop 40. The operating lever 170 has a T-shaped end a part 170c of which normally enters a slot in a slotted member 224 attached to the counter stop carriage support 114 to hold it in its normal position against a spring 140. When the operating lever 170 is actuated the part 170c is withdrawn from the slot of a member 224 of the counter stop carriage so that it is advanced by a spring 140 thus preventing the lever 170 being restored by the engagement of the part 170c with the member 224 until the set counter stop engages a column stop forcing the counter stop carriage back against the spring 140 and allowing the end 170c to enter the slotted member 224 once more. To prevent the return of a raised counter stop before the operating bail 168 is released a latch mechanism 202, Fig. 1, is provided by a member 204, attached to an arm 150b of a bell crank 150 of the mechanism of the tab key 108 engaging a bail member 208, attached to the power unit 172. As soon as the lever 150 is rocked to commence to raise the stop the latch prevents the return of the stop until unlatching which occurs only after the power unit has been operated. If a tabulating stop is set when no column stop has been set or after the carriage has passed the point of contact of two stops the engagement of the usual margin stop at the end of the carriage is utilized by a mechanical connection to restore the counter stop carriage to its normal position and to thus return any counter stops set. A usual tab key 108 is provided and is operatively connected with the counter stop which allows full movement of the main carriage and is provided with a special connection with the actuating member 192 to allow positioning of a counter stop before the power unit is actuated, the main carriage being released by the movement of the operating lever 170 through a lever 228 engaging the escapement pawl 98. Letter-spacing mechanism.-The main platen carriage 26 is biased in a letter-spacing direction by a spring motor 92 and is held by engagement of a pawl 98, Fig. 2, with a rack 104 fixed to the carriage. The pawl 98 is pivoted on a fixed stud 100 with a slot 98a and is biased into engagement with the rack and counter to the letter-spacing direction by a spring 102. On release of the pawl from the rack against the spring 102 by a universal bar 106, in the path of each type bar, acting through a trip lever, the stud 100 engages the other end of the slot 98a by which point the pawl is out of contact with the trip lever and thus re-engages the next tooth on the rack. Back spacing is effected by a pawl 288 pivotally mounted on a slide 292 which in its normal position causes the pawl 288 to be held out of contact with the rack 104 by a boss 300, but on rocking a lever 296 by poweroperated mechanism the slide 292 is shifted to the right, Fig. 2, moving the pawl 288 away from the boss 300 so that it engages the rack 104 to move the carriage. Interlock arrangements.-To prevent operation of the back spacing pawl during tabulation an interlock is provided comprising a U-shaped member 302, Fig. 4, an arm 302e of which is engaged when the operating lever 170 leaves its normal position thus moving the other arm 302e into the path of the back space pawl 288 to prevent its rotation into contact with the rack. Another mechanical connection, Fig. 7 (not shown), between the lever 170 and the trip lever 308 for the carriage return prevents operation of the return during tabulation. Also a lever 326a, Fig. 3, interposed in a link 310 connected to the trip lever 308 for the carriage return ensures that on actuation the rebound pawl 242 is withdrawn from the rack by engagement of its arm 326b with an extension 242b of the pawl. Rebound preventing,-As the main carriage moves with considerable velocity it tends to rebound when a counter stop engages a set column stop and to prevent this a lug 250b of a bracket 250, Fig. 3, secured to the counter stop carriage 114 moves out of the path of an arm 242a, Fig. 2, as the carriage 114 moves past its normal position from its advanced position as the stops engage thus allowing a spring 248 to engage a rebound pawl 242 with a rack 244 attached to the tab rack 24 to prevent rebound of the main carriage. Further rebound from the rebound pawl is prevented by the escapement mechanism. Type bar action.-Depression of a character key 57, Fig. 1, by a lever 58 causes a power unit 55 to engage an electric-motor-driven roller 56 by an operating cam 82 engaging therewith thus to actuate a type bar 54 through linkage including a sublever 68 and links 74. Specification 660,263 is referred to.