Patent GB-455799-A (GB)
Title: Improvements in and relating to printing telegraph apparatus
IPC: H04L17/06
Filed: 1935-05-30
Abstract: 455,799. Type-printing telegraphy. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. May 30, 1935, Nos. 15777 and 15778. Convention dates, May 30, 1934 and Feb. 6, 1935. [Class 40 (iii)] Means are provided for preventing a keyboard transmitter from being set to a type case different from that to which the receiver at the same station is set. If the transmitter begins to send in a case different from that in which the last signal was received from the distant transmitter, it automatically sends a case-shift signal under control of the local receiver. In view of the overlap between the sending and printing of a signal, the means whereby the local receiver controls the keyboard is disabled so long as the latter is actually transmitting. Alternatively, the receiver may cause the transmission of a case-shift signal while the transmitter at the same station is idle. Preferably separate keys are allocated to the upper and lower cases, the keys allocated to one coil are locked by the local receiver and a case-shift signal is automatically sent when keys necessitating a case-shift are operated. The keyboardlocking bars 1, Fig. 1, is shifted to lock the keys belonging to one or other case whenever one or other of the push bars 8, 9 is actuated by the receiver so as to push over the corresponding flap 5 or 6 and actuate the locking-bar 1 through the shaft 3. So long, however, as the transmitter shaft 10 is running this device is kept out of action by a spring 13 which draws the lever 12, rod 7 and flaps 5, 6 to the right whenever the lever 12 is disengaged from the worm 11 by the arm 15 at the beginning of a transmitter signal-period. As soon as the arm 16 re-engages the worm 11 it is carried to the left by the worm and at the end of the signal-period restores the flaps 5, 6 to their operable position. In a modification, Fig. 2 (not shown), the typewheel, according to its axial position, prepares a circuit for one or other of two magnets, the circuit being completed by the armature of a cam-controlled relay at the end of each revolution of the transmitter shaft so as to permit a condenser to be discharged through the selected magnet for the purpose of shifting the keyboard-locking bar. In a further modification, Fig. 3, the hammer 46 which drives the type-bars also, if the receiver and transmitter are set for different cases, actuates a lever 47 which, if the interponent 48 is in the position shown, depresses the point 49 and thus centres the keyboard-locking bar 1 so that the keys belonging to both cases are locked. Before further transmission can take place the keys must be unlocked by depression of one or other of the case-shift keys 42. If the local transmitter is in operation, however, the above device is put out of action by the worm 11 which removes the interponent 48 to the right. In a transmitter of the kind in which the signals are stored in the settings of groups of five pins 58, Fig. 4, on a drum 24, a case-shift signal corresponding to the position of the locking-bar 1 is set up on depression of one pin by the pawl 32 acting on lever 34, or by the pawl 58 as the case may be. A hammer 27 is raised or lowered according to the position of the locking-bar 1, and when it is driven by the cam 31, which makes one revolution when the key has been actuated, one or other of the projections 17, 28 drives in the corresponding lever 56 or 30, and so raises the stop roller 35 to release the other lever 30 or 56. When the station is receiving and the keyboard is idle, a receiver cam 22 acts through a rod 19 to lift the stop roller 35 and release both levers 30, 56, ready for them to be set by the next action of the transmitter ; but this arrangement is put out of action by a cam 36 so long as the transmitter is in action. Specifications 336,278, [Class 40 (iii)], 388,785, and 442,662 are referred to.