Patent GB-643153-A (GB)
Title: Improvements in or relating to printing telegraph apparatus
Inventor: SALMON REGINALD DENNIS
IPC: H04L17/18
Filed: 1947-03-14
Abstract: 643,153. Type-printing telegraphy. CREED & CO., Ltd. March 14, 1947, No. 7142. [Class 40 (iii)] In a printing-telegraph receiver employing letter-shift and figure-shift signals to condition the receiver to a lower case or an upper case condition so that any one of a plurality of signals has correspondingly different effects according to whether the receiver is in the upper case or lower case condition, there is provided means responsive to a secondary shift signal when the receiver is in the upper or lower case condition to operate the receiver to cause any one of a plurality of subsequent received signals to have a respective effect different from that which it has when the receiver is in the upper or lower case condition. The arrangement is such that when the secondary shift signal is followed by two different signals, the receiver is restored to operate in the case condition which existed prior to the reception of the secondary shift signal. If the signal following the secondary shift signal is repeated one or more times the corresponding function is correspondingly repeated. In the arrangement shown, notched function levers are associated with pivoted code selector members comprising longitudinal rods 17 associated with notches 38 in the function levers and the arrangement is operated, as described in Specification 620,682, to operate a pivoted case-shift vane 60. The reception of the secondary shift signal, preferably constituted by an all-blank signal, i.e. all selecting code elements spacing, permits a function lever 31 to move inwardly under the action of its spring 37 and a projection 122 carried by the lever 31 engages a segment 123 mounted on a vane 119 which is rotated clockwise and retained by a spring-biassed latch 124, the latter being moved to the right a short interval prior to the setting of the members 18-22 by a pivoted arm 129 operated by a cam 131 rotated in response to each received signal. The lever 31 is cut away, as indicated at 190, opposite the end of the shift vane 60. When the signal following the secondary shift signal is received, the function lever 31 is cammed outwardly and a selected function lever, such as lever 33, Fig. 3, which is provided with a slot 128 opposite to the end of the vane 119 in its actuated (horizontal) position moves inwardly and controls the performance of the corresponding function. The slot 128 is partly blocked by a spring- biassed pivoted member 191 and when the latch 124 is rocked prior to the setting of the code members 18-22 corresponding to the subsequent signal, the vane 119 rotates to the position shown in Fig. 3 in which it is free of the latch 124 and is supported on the member 191. If the subsequent signal is the same as that which followed the secondary shift signal the function is repeated, but if the subsequent signal is different, the lever 33 is cammed to the left, and the vane 119 is moved to its non-operated position in which it prevents operation of a secondary shift function until the secondary shift signal has again been received and the receiver is thus restored to operate in the case condition which existed immediately prior to the receipt of the secondary shift signal. By using a secondary shift signal in conjunction with normal case-shift signals in the usual five unit code a telegraph receiver can provide for 26 letters in the lower case, 10 numerals and 14 symbols in the upper case, bell and answer-back operations controlled by figure-shift, followed by a lower case letter and three functions controlled by signals independent of case condition, the secondary shift vane being in the unset position. With the secondary shift vane in the set' position, twenty-six additional functions can be provided irrespective of the position of the case-shift member. Specification 388,875 is referred to.