Patent GB-657892-A (GB)
Title: Improvements in and relating to differential letter spacing for typewriters
IPC: B41J19/32
Filed: 1947-07-31
Abstract: 657,892. Typewriters. COXHEAD CORPORATION, R. C. July 31, 1947, No. 20746. Convention date, June 23, 1939. [Class 100 (iv)] In a typewriter wherein any one of a number of fonts of type may be employed, the carriage escapement mechanism is arranged to release the carriage for spacing movements in accordance with the varying widths of the letters &c. and the unit of spacing can be varied in accordance with the particular font in use, the ratios between the movements for the various letters remaining unaltered. As applied to a machine employing interchangeable type shuttles 9, the carriage 16 is driven by a spring drum 19, Fig. 1, which through an escapement rotates a shaft 41 carrying gears 32, 34, 35 one of which engages a rack 31 mounted on the carriage. By means of a spindle 24 with a setting knob 25, the rack 31 can be lifted clear of the gears, and the gears moved axially on the shaft 41 so as to bring into mesh with the rack that gear which gives the desired unit spacing. Each type-key 5 is associated with one to three depending rods Ia, IIa, IVa, Figs. 2, 6, which pass through holes in an arcuate plate 47 having restricted endwise movement on pins 48. The plate 47 is held in its normal central position by spring jaws 52, 54, Fig. 6, engaging a pin 51 thereon and is moved either to the left or to the right by the depression of capital and figure shift keys 22, 21 respectively, carrying the lower ends of the rods Ia, IIa, IVa, with it. The shift keys act on a cam-plate 64, Fig. 3 (not shown), having a pin-and-slot connection with a bracket Ib, IIb, IVb respectively, one or more of which are depressed by the rods when a key is actuated. The number of and the particular bar or bars depressed is determined by slots suitably disposed in their upper faces. When a slot in a bar is situated beneath a rod, that bar is not depressed when the corresponding key is actuated. Depression of a shiftkey causes the disposition of the rods relatively to the bars to be altered, and thus the bar or bars depressed are varied. Movement of a bar Ib, IIb, IVb depresses one end of a corresponding lever Ic, IIc or IVc and raises the far end to which is pivoted an escapementoperating link Id, IId or IVd. Each link, e.g. link Id, Fig. 8, is pivoted to an escapement dog Ie and when operated by a type-key causes a retaining-dog 105 to be released from a toothed disc If of the escapement, and a dog 106 to be moved into engagement with the disc thus permitting a slight movement of the disc under the action of the escapement spring. As the type key returns to its raised position, the dog 106 is lowered and the dog 102 reengages the disc If, thus allowing the latter to complete a movement of one tooth-space. The links IId, IVd similarly operate toothed discs IIf, IV f, Fig. 13 of the escapement. The discs If, IIf, IVf, and the shaft 41 are coupled together by an epicyclic gearing 88, 89, 91, 92, 99, 101, 104, the arrangement being such that actuation of a link Id, IId or IVd causes a spacing movement of one, two or four units respectively and operation of more than one link causes a spacing movement corresponding to the sum of the separate movements. Thus, according to the key depressed, and whether a shift-key is operated, one or more of the universal bars Ib, IIb and IVb are depressed and one or more of the escapement discs If. IIf, IVf are released to give the required spacing. Carriage - releasing arrangements.-A tabulating key 110, Fig. 1, actuates a lever 111 which pushes upwards on a tail 112, Fig. 8, provided on the tail of the dog 105 of the escapement dog Ie, thus releasing the escapement disc If and allowing the carriage to tabulate. U.S.A. Specifications 1,880,592, 1,918,299, 1,930,068, 1,965,677, 1,985,419 and 2,051,112 are referred to.