Patent GB-1053186-A (GB)
IPC: B41J19/64
Abstract: 1,053,186. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 7, 1964 [Sept. 25, 1963], No. 36628/64. Heading B6F. Variable escapement mechanism, letter-space actions.-Movements of a carriage with respect to a typewriter frame is controlled by a storage wheel 30, Fig. 2, which comprises a number of stops 35 displaceable according to the amount of letter-space required and which are engaged by an escapement pawl 43. The stops 35 are in units and as described are arranged so that letter-spaces of two, three or four units of space are provided by the carriage movement. The stops 35 are resiliently held in slots in the wheel by a spring garter 38 which engages in recesses 36, 37. In a set position, Fig. 3, a stop 35 is shifted to the right so it is engageable by the pawl 43. The alternate detent pawl is holding pawl 50 and operates in an annular recess 52 so it engages the stops whether they are set or reset. Operation of the escapement mechanism is effected by a pull on link 49 from a bell-crank 119 operated from cam 117 on shaft 112 rotated on each key-action. This pivots trip lever 48 and a constant torque drive described in Specification 1,053,187 advances the wheel 30. The bent end of pawl trip lever 48 pivots pawl 43 which is released from stop 35 and slides forward on pin 45. This disengages the top end of pawl 43 from bent end of pawl trip lever 48 so pawl 43 pivots to engage the next stop 35. Engagement between pawl 45 and the next stop 35 moves pawl rearwardly until stopped by pin and slot 44, 45 and defines the end of that escapement movement determined in amount by gap between set stops. The holding pawl 50 is necessary for back-spacing operations pefined in Specification 1,053,185, but in forward letter-space movements a tab 53 on pawl 43 holds an extension 54 on the holding pawl 50 so it is held clear of the stops until pawl 43 engages the next set stop 35. The setting of the stops 35 is made in accordance with the character width required. Each key, e.g. lever 21, Fig. 1, has a character interposer 90 which when depressed effects a cyclic clutch to operate a driving shaft 93. Thereupon shaft 93 drives interposer 90 forward and coded projections 90 tilt selected bails 91 to select the right character by means of pulleys, and in order to select the appropriate character space bails 94, 95. Bail 95 operates when a four-unit space is required, pulls link 97 and wire 98 and actuates link 86 on the stop setting mechanism, Fig. 2. Bail 94 the two-unit selector bail has a plurality of flags 100 of different widths (for variation of width in different case-shifts) and when engaged by a raised projection on an interposer pull a wire 102 and actuate a link 77 of the stop setting mechanism. The setting mechanism has a further link 66 which is actuated upon every action from a wire 103, latch 104, bell-crank 109, follower 110, cams 111 driven by the drive shaft 93. The links 66, 86, 77, Fig. 2, operate scissor mechanisms with projections 74, 83 and set the stops for the different spacing. Link 66 with link 77 gives two units, link 66 with 86 gives four units, while link 66 on its own gives three units. Carriage-release.-A forward space key lever 185, when operated, actuates bail 115 to suppress stop setting by operating wire 120, a link 49, Fig. 2, to lift the pawl 43 clear of stops 35. Back-spacing.-Back-spacing in the same increments as the forward spacing is ensured by the stored information comprising the set stops 35 and is described in Specification 1,053,185. Collectively adjusting the variable spacing.- When type-heads of differing sizes are fitted the distance of travel of the storage wheel 30 and the travel of the type-head carriage 15 is adjusted by a gear lever 216, Fig. 8, and gear-box 28 described in Specification 1,053,188. Scales and indicators.-Adjustment of the size of each letter-spacing arrangement also correspondingly adjusts a visual indicator to show the typist the usable character information stored in the memory and is coupled to the gear-box 28. As shown in Fig. 1, the gear lever 216 turns shaft 219 and via linkage 218, 214, 225, 226 a scale member 228 extending across the machine, is rotatable to present three sets of reference indica. These are read through a character storage indicator 230 comprising a tube 231 with window openings which rotate with the pivoting of the scale 228. The storage indicator 230 is slidable in key-ways in the scale, being moved by a projection 237 fixed on the type-carrier 15. A pointer 229 is mounted with the projection 237 to indicate the position of the print head within the store of character spaces.