Patent GB-823454-A (GB)
Title: Improvements in typewriters and other typing machines
IPC: B41J7/02
Filed: 1957-04-30
Abstract: 823.454. Typewriters. FINE, L., and AUERBACH, A. E. April 30, 1957 [April 30, 1956], No. 13732/57. Class 100(4) Type-lever actions, actions using auxiliary power, impression arrangements. A quick acting, noiseless type-action comprises a type-lever 36 which is moved into impression-forming area by a key-lever 50, whereupon contacts 84 are closed by the type-lever 36 to effect energization of an electromagnet 74 which sets up a magnetic field causing a soft iron slug 44 to pull on the type-lever 36 so that the type 42 forms a typing impression. The key-lever 50 has pivotally mounted at 62, a spring 64 biased dog 60, which coacts with a shoulder 67 on the type-lever 36. The travel of the type-lever 36 from a rest is short as this movement is not used to effect impression. As the type-lever 36 approaches printing position the dog 60 pivots against the face of the spring 64 and slides off the shoulder 67 so it is free for partial return. Closure of the contacts 84 (see Fig. 4) energizes a relay 98 and causes armature 104 to contact a point 96. This discharges a condenser 116 (which has been charged up by a circuit including a resistance 110) through a winding 76 of the electromagnet 74 to effect the typing impression. Repulsers. The type-lever may be repulsed by an additional electromagnet 150, Fig. 10, which is energized by the closure of contacts 84. A delay circuit ensures that electromagnet operates after the impression electromagnet 74 has operated. The springs 142 and 78 and a separate pivoted lever on the pole-piece of the magnet 74 may also assist in type-lever repulsion. Adjustment of impression. Collective adjustment to the force of impression is made by the inclusion of more or fewer condensers 118, whose discharge operates the electromagnet 74. Letter-by-letter adjustment is made by modification of the size and shape of the soft iron slugs 44. Type-lever construction. The type-levers are dovetailed to accommodate the slugs 44 and since they have to move the type into printing position only, the face to make the impression coming from the electromagnet 74, the type-levers may be of light construction. Aligning for impression. The pole-pieces 70 of the electromagnet 74 may be shaped to guide the slugs so that the type-faces 42 are correctly aligned. In a modification, a single pole piece is employed which is tapered to concentrate the magnetic field which attracts and guides the slugs 44 accurately to printing position. Space-key actions. The operation of a space-key closes contacts 170. Fig. 4, operates relay 98, and by the discharge of the condenser 116 operates the electomagnet 74 (74f, Fig. 14). This attracts a slug 164 into a recess 158 in the electromagnet 68f and actuates the escapement or carriage advancing linkage 160, 168. Carriage-returning mechanism. The operation of a carriage-return key closes contacts 186, Fig. 16, to energize a solenoid 184, raise the detent 182, and a plunger 176 is expelled by a spring 180 from a hollow portion 174 of an electromagnet 74. A hook 188 engages behind an arm 192 and contacts 207, in parallel with contacts 84, Fig. 4, close and energize the magnet 74. The plunger is thereby pulled back in the hollow 174 and a spring retractable tip 202 on the arm 192. in engagement with a carriage ,rack, throws the carriage in a carriage-return direction and return is completed by carriage inertia. A modification. employing a single pole electromagnet is described, (see Fig. 17 not shown).