Patent GB-673685-A (GB)
Title: Improvements in or relating to typewriting machine
IPC: B41J19/32
Filed: 1949-07-06
Abstract: 673,685. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. July 6, 1949 [July 8, 1948], No. 17850/49. Class 100 (iv). Power - operated type actions; letterspacing.-A variable letter-spacing mechanism includes a carriage rack 75 having a series of stop elements or teeth, Figs. 20A, 20B, spaced at regular intervals of a fixed number of spacing units with which coacts a series of space-control members or pawls 69A-E mounted for movement by the rack 75 in a character spacing direction by extents differing by single space units, the teeth 72A of the pawls 69A-E being releasable from the rack 75 in one or more combinations to enable the rack 75 to move an extent determined by one of the remaining pawls. The type action is similar to that described in Specification 660,263 but in addition the sublevers 19, Fig. 1, associated with each type-bar action, have connected at 19D horizontally sliding selector bars 48 carrying varying-shaped lugs 48A, 48B (or none at all) which engage, in various combinations, bails 42 A, B, C. These bails are pivotally mounted on end. plates 41 vertically movable by a linkage from a case shift mechanism described in Specification 655,492 so that the lugs 48 A, B, C may engage different bails or combination of bails if the letter-spacing required by upper and lower case is not the same. If no bails are engaged by the sliding action of a bar 48, two units of space are effected as described below, while individual operation of bails 42 A, B, C effects three, four and five, units respectively by engaging arms 50 A, B, C, Figs. 1 and 2, connected by links 51. A, B, C and arms 52 A, B, C vertically moving through forked connections 54A three interposers 55 A, B, C so that the selected interposers may be moved to actuate the rack escapement pawls 69A-E by means of a common operating member 63 pivotally actuated by a link connection 64 from a universal bar 65 engaged by the type bars 16. The interposers 55 A, B, C are mounted on a stud 56 together with a non-slidable interposer 61, Fig. 3, which is in consequence always operated by the member 63 and effects two units of space unless one of the other interposers is raised to effect a larger spacing. The rack escapement pawls 69A-E, see Figs. 20A, 20B, have teeth 72A normally in engagement with teeth of the carriage rack 75 spaced 6 units apart. The pawls are slidably and pivotally mounted on a stud 70A and urged by springs 74 to the left but are moved to the right by the usual rightward carriage return pull. In the position shown in Fig. 20A pawl 69A is holding the carriage since the stud 70A is in engagement with the left-hand end of a slot in the pawl. If two units of letter space is required the interposer 61 engages the tails of pawls 69A-B since they are to the right of its striking line indicated by the dotted line, and the teeth 72 of these pawls are withdrawn from the rack. The rack now moves to the right, and since the teeth 72A of pawls 69 C, D, E are still engaged with the rack these are moved rightwardly until the stud 70A reaches the left-hand end of the slot in pawl 69C. The slots in pawls 69A-E are staggered to the extent one unit of space so that in this action two units of space are effected. Three, four or five units of space are similarly effected by the action of interposers 55 A, B, C on pawls 69 C, D and E. A sixth pawl 69F is provided for use when increased spacing is required for every character, the interposers 61, 55 A, B, C being moved bodily to the left one unit of space so that interposer 61 effects three units of space and interposer 55C engages the pawl 69F to effect 6 units of space. Tabulating.-A tabulating lever 90, Figs. 3 and 4, is rocked anticlockwise by the powermechanism in a horizontal plane on a pivot 91, to place a stop lug 90A in the path of a tabular stop on the carriage and actuates a release lever 92. A lug 92C on the release lever 92 which may also be actuated by hand by a release bail, engages a lever 95, Fig. 7, pivotally carrying on its opposite end a lever 97 extending upwardly to a position to engage protrusions 72 formed on the escapement pawls 69A-F, the upward movement releasing the pawls 69A-F and a tabulating pawl 107 from the rack 75 allowing the carriage to move freely under the pull of the usual carriage spring. When released all the pawls move to the left by the pull of the springs 74 permitting a lever 102, engaging in a slot 107A, to rock anticlockwise and turn a lever 100 clockwise to latch into a notch 99C on a latch 99 that has been moved anti. clockwise by the engagement of part 99A with an adjustable eccentric 98 on the lever 97. The release of tabulator lever 90 by contact of a tabulator stop on the carriage or by the handoperated bail 94 therefore permits lever 97 to return to normal in turn permitting all pawls to re-engage the rack 75. Latch 99 however is held in shifted position where its bail member 99B engages a lever 105 fixed to a lever 106 extending into slots 71 in pawls 69A-F which are thus held to the right so that the three pawls 69A-C and three pawls 69D-F are spaced three units apart as shown in Fig. 14. This enables the carriage to move an additional three units at the end of a tabulating operation since a single unit of spacing is not practicable in the tabulator stop rack: The movement of pawl 107 three units to the right rocks lever 102 clockwise releasing the latch 99. Carriage-returning mechanism.-A carriagereturn trip lever 110, Fig. 4, is operated and engages a lug 92D on the release lever 92 which is turned anticlockwise to release the pawls 69A-F from the rack. When the left-hand margin stop approaches the trip lever 110 the power return mechanism is disengaged, allowing the carriage to coast until it is arrested by the engagement of the margin stop with the lug 90A on the tabulator lever 90. The disengagement of lever 110 restores release lever 92 and the pawls re-engage the rack. Back-spacing; key interlocks.-A power-operated link 130, Fig. 2, is drawn forwardly to effect one unit of back-spacing, pivots a lever 128 and by a connection link 127 moves anticlockwise a lever 126. Lever 126 carries pivoted thereon, three pawls 132 each with two teeth 132A, the teeth on each lever being displaced relatively to one another by one unit of space so that the rocking of lever 126 allows one of them to engage the rack 75 which is moved leftwardly until ends 132B of the pawls 132 engage an adjustable stop 135. This leftward travel is just over one unit of space to allow free engagement of escapement pawls 69 simultaneously arranged in a staggered formation by a link 136 attached to the lever 128 and which is operatively connected, Fig. 4, to the lever 97 that engages the lugs 72 on the pawls 69. This ensures that when the back-space pawls are released one of the pawls 69 will hold the carriage. When tabulating or during a carriage-return movement, back-spacing is prevented by the positioning of a lug 105B on the lever 105, Fig. 7, in front of depending tails 132C on the pawls 132 which are thus prevented from engaging the rack.