Patent GB-402453-A (GB)
Title: Improvements in start-stop telegraph systems and apparatus therefor
IPC: H04L17/00
Filed: 1933-06-02
Abstract: 402,453. Type-printing telegraphy. CREED & CO., Ltd., and GRIFFITH, R. G., Telegraph House, Croydon. June 2, 1932, No. 15639. [Class 40 (iii).] In a type-printing telegraph system, the transmitter and receiver are adapted to be operable alternatively according to a five-unit or a six-unit code. When the system is operated on the five-unit code, case selection is effected by transmitting the appropriate signal combinations, whilst with the six-unit code, the case group is determined by the character of the sixth unit or element. Keyboard transmitter. When the system operates according to the five-unit code, a change-over lever 28, operated to the position shown in dotted lines, holds a latch member 27, secured to the sixth bar 17, out of engagement with a notch in an actuating bar 26 which is also locked against movement. On depression of any key lever 10, 11 ... the bars 12-16 are selectively moved and a universal bar 58, invariably moved to the right, actuates a pivoted clutch detent 55 to release a toothed disc 54 which allows a cam shaft 30 to be connected by a friction clutch to a gear 53 driven from a constantly rotating gear 68. The selective setting of the bars 12-16 is transferred to pivoted T-members 18-22 having vertical arms 37, 38 which are selectively placed into an engaging position with respect to rods 44, 45 carried in pivoted members 46, 47. through which a contact member 60 is actuated to one or the other of two contacts 61, 62. Cams 31-35 with diametrically opposed projections engage the pairs of arms 37, 38 in sequence and rock the member 46. A cam 84 on the shaft 30 coacts with a rod 83 to move a bar 81 with projections 82 one of which enters a hole 85 in the depressed key lever and the remainder of which pass under the key levers to prevent their actuation. The start impulse is transmitted by a cam 39 actuating a rod 43, whilst the stop impulse of opposite polarity is transmitted by a rod 37 operated by a cam 36. On transition to the six-unit code the operation of the changeover lever 28 allows the spring actuated latch 27 to connect the bar 17 to the bar 26. If the sixth selecting impulse is of the same polarity as the normal stop impulse bar 17 is not moved, and after the transmission of the sixth impulse current of the same polarity remain on the line. When, however, the sixth impulse is of a different character from the normal stop impulse in the five-unit code, the bar 17 is moved to the right, rocking the associated T-member 23 to place the bar 38 in operative position with respect to the contact bar 45, and at the same time to move a pivoted latch member 73 out of engagement with a member 74 pivoted at 71 and controlling the rotation of a second cam shaft 66. After the shaft 30 has rotated through a small interval corresponding to the period of the start-impulse, one end of the unlatched member drops into a recess and the other end is raised clear of a notched disc 69 allowing the shaft 66 to be rotated through hall a revolution. A cam 86 co-operates with a spring-actuated member 88 and a lever 87 to lock the keyboard, whilst a cam 78 rocks a lever 79, towards the end of the half revolution, to engage the bar 44 transmitting the stopimpulses. Receiving arrangements. The start impulse rocks a shaft 150 depressing the arm 151 and releasing a clutch controlling detent 152 as described in Specification 378,507. On rotation of the sleeve 102, a cam 113 operates a detent 115 releasing a second cam-sleeve 103 which oscillates a striker blade 161, and draws an abutment pin 154 across a series of actuator bars 155-160 as described in Specification 228,842 [Class 40 (iii), Telegraphs, Electric]. In accordance with the rocking of the shaft 150, the striker blade 161 co-operates with the actuating pin 154 to set the actuator bars 155- 160 mounted on a shaft 162 in a frame 163. After the bars have been selectively set the frame member 163 is raised so that the five selector bars 201 are moved longitudinally through pivoted members 204. The case selection bar 200 is similarly moved through a single-arm pivoted member 205 engaging the end of a slotted member 209 sliding on pins 211 secured to the bar 200 or by an independent lever 207 of which one end engages a slot in the bar 200 whilst the other end co-operates with the bar 160 through an interposable member 208. When the five-unit code is being utilized, the shift or unshift signal combinations position the selecting bars 201 so that one of the bars 202, 203 falls into the aligned slots and a printing bail 217 moves the selected bar to the left. The bars 202, 203, which are moved to the left for the printing of letters and figures respectively, carry projections 215, 216, engaging the arms of a pivoted T lever 213 which co-operates with a slot in the bar 200 to move it to the right or to the left to print letters or figures respectively Since the invariable setting of the bar 160 by the stop element of the fiveunit code determines one of the case groups for the six-unit code and since this setting will not in some cases, during operation according to the five-unit code, correspond to the case group of the character transmitted, it is necessary to prevent the bar 160 from determining the position of the case controlling bar 200 during the five-unit code transmission. When, after the transition to the five-unit code, a shift signal is transmitted, the bar 203 is moved to the left for the printing of figures. The projection 216 engages the T member 213 moving the bar 200 to the left and at the same time through a projection 220 engages a bell crank 219 which through a projection 221 moves the member 208 to a position in which it is latched by a member 224 out of operative engagement with the bar 160. During the fiveunit code transmission the case controlling bar 200 is moved by the T-member 213 with the pins 211 on the bar sliding freely in the slotted member 209. On the transition to the six-unit code a signal having a figure-shift element is transmitted so that the bar 200 is actuated to its left-hand position by the member 160 to remove the latch 224 from the interposable member 208. Specification 397,923 also is referred to.