GB493467A - Improvements in telegraph printer systems - Google Patents

Abstract

493,467. Type - printing telegraphy. FINCH, W. G. H. April 9, 1937, No. 10217. Convention date, April 10, 1936. [Class 40 (iii)] A telegraph transmitter suitable for use with the receiver described in Specification 437,303 or other code telegraphy system generates, on the depression of any key, a predetermined number of short impulses some of which, according to the key depressed, are modified to become long impulses. A number of permutation bars 12, are arranged beneath the key bars 10 so that on depression of a key they are either held or capable of lateral movement when urged successively by rotating cams 14 on a shaft 60 driven through a friction clutch 63, 64 by a constantly rotating motor 69. The permutation bars, when so moved, close contacts 16, 17 by means of a common bar 41. The construction of the central permutation bar is such that it is not held by any of the key bars and its associated cam has twelve equally spaced projections so shaped as to send eleven dots and one dash per revolution. The remaining cams each have one projection only corresponding to a dash and are arranged helically so that each is in a position corresponding to one of the projections on the central cam. Thus any bar which is not held by a key, when moved, converts the corresponding dot of the central bar into a dash. A detent, Fig. 4 (not shown), operated directly by the depression of any key releases the cam-shaft, and allows it to make one revolution and a mechanism operated through a lever 88 by a cam 62 holds the keyboard locked until the revolution of the cam-shaft is almost completed.