Patent GB-922520-A (GB)
IPC: B41J1/00
Abstract: 922,520. Typewriters etc.; ink ribbon mechanism. WESTERN STAMPING CO. May 13, 1960, No. 17025/60. Class 100 (4). A typewriter has an escapement mechanism and a carriage drive as described in Specification 759,519 and may have a similar main framework consisting of stamped metal parts or the cover may be modified by being moulded in a single piece from plastic material. Keys, keyboard, and type space bar mechanism.-Keys 46, Fig. 2, are integral with levers 47 to 49 which are pivoted in slots in a bar 44 and are each connected to a corresponding bell-crank 54. Bell-cranks 54 are connected by links 58 to type bars 59 for their actuation and are guided by slots 53 of a bar 62. Each type bar 59 has a guide portion 66 housed in a slot 65 of an injection moulded hanger 64 and is pivoted on a wire 67. Space bar 234 secured to bell-cranks 235, Fig. 12, operates the universal bar 136 also operated by each type bar to effect the carriage escapement. The return of all the keys is effected by a spring 137 engaging the universal bar 136. In a modification, a comb leaf spring returns the type bars and a weaker spring returns the universal bar. The type bars each have three type faces 74 and are guided to effect impression by a guide 76, Fig. 4. Carriage mounting.-A carriage assembly 85 comprising a carriage 107, Fig. 5, running on a rail 105 is mounted by means of brackets 86, Figs. 2, 12, on posts 42, 43 of a frame 41 to which they are connected by torsion links 93, 89 respectively. The carriage rest position can be adjusted to give maximum contact between the type faces 74 and the ink ribbon 84 by adjustment of the position of rest plates 96, Fig. 16, relative to the frame 41 the stop edge 95 of the bracket 86 resting thereon. Case shift.-The type bars having three type faces the carriage can be shifted to an intermediate or an upper position. For the intermediate position either shift lever 241 or 242 by engagement of its opening 244 with the torsion spring 93 raises the carriage assembly to the intermediate position in which it can be locked by sliding the lever 241 or 242 to engage its notch 246 with a projection on the carriage stops. A similar key lever produces shift to the upper position and if the carriage was locked in the intermediate position the upper edge of the opening 244 cams the effective lever 241 or 242 to the inoperative position. In a modification only a single non-lockable shift mechanism is provided. Platen, paper guides.-The platen 144, Fig. 5, consists of a wooden core 145 and a sheath of plastic material 146 forced thereon in a stressed condition with the aid of a forced air apparatus and is mounted for rotation in the carriage by pins 156, 157, Fig. 17. The paper is guided around the platen and gripped thereon by a guide 177, springs 179, and a bail 182. Swing- ing of the guide 177 clockwise causes the edge 185 to force the springs 179 away from the platen to allow insertion of the paper. Line spacing.-Knobs 162, 163 are fixed on the pins 156, 157, Fig. 17, to effect line spacing of the platen. Line location of the platen is effected by co-operation of a button 171 on a spring disc 165 secured in the knob 163 with ratchet teeth 164 on an ear 159 of the platen support. Carriage release and return, alarms.-Carriage release is effected by a handle 191 which engages the tab 186 of the escapement cage 119 to rock the latter to an inoperative position to release the carriage. A shouldered projection at one end of the carriage rack engages and operates an alarm bell as the end of a line is reached. In a modified construction described the carriage release lever is actuated by a finger piece which also by a pawl and a ratchet device moves the platen for line spacing. Ink ribbon mechanism.-The vibrator is actuated by a lever 139, Fig. 5, supported on the universal bar link 134 acting through leaf springs 142, 143 to raise the guide 81. The ribbon 84 is fed between spools 205, 206, Fig. 4, by wires 218 or 219 or a shaft 215 engaging a wheel 213 to turn a shaft 207 or 208. The shaft 215 is rotated by a pawl connected to the universal bar 136 engaging a ratchet 221. Feed is reversed by a handle which causes one other wire 218, 219 to engage its wheel 213.