Patent GB-191211464-A (GB)
Title: Improvements in Impulse Transmitters for Semi-automatic Telephone Systems.
IPC: H04M1/272
Filed: 1912-05-14
Granted: 1912-11-07
Abstract: 11,464. Siemens & Halske Akt.-Ges. May 16, 1911, [Convention date]. [Addition to 10,444/12.] Semi - automatic exchange systems. - Relates to a modification of the operator's keyboard impulse - transmitter described in the parent Specification, in which the impulses corresponding to the digits of the wanted subscriber are sent out by means of a single feeling-device, such as a rotary step - by - step switch, which is restored to its normal position as soon as it has reached the depressed key on the row which is being tested at that time, and repeats the process for each succeeding digit. In the invention described in the parent Specification, a separate switching-device is used to associate the feeling- device with each row of digit keys in succession, but according to the present invention this shifting movement is effected automatically on the release of the feeling - device, so that no auxiliary switch is required. In the form shown in Figs. 1 and 2, the feeling-device consists of a projection 12 on a plate 11 sliding on a rotary frame 16 secured to an interrupting- sector 6 which engages a lever 10 controlling the impulse-contact 8. The sector 6 and frame 16 are rotated by a pawl 18 which engages a ratchet-disk 5, fixed to a shaft 4 driven by gearing 2, 3, which is brought into operation electro-magnetically when the units key is depressed. As the sector 6 rotates, the contact 7 earths the a and b lines, and then the lever 10 intermittently opens the a-lead. During the first movement, an arm 13 on the plate 11 engages an inclined surface 14, thus moving the plate 11 to the right until a pawl 15 engages the next tooth on the underside of the plate 11. The projection 12 is thus brought into the path of the thousands keys, and the sector 6 and frame 16 rotate until the projection engages a depressed key, when the frame causes the arm 17 to raise the driving-pawl 18, thus releasing the sector and frame, which are returned by a spring 20 to their normal position. During this movement, the arm 13 moves over the surface 21, and when the normal position is reached, it springs beneath it, so that during the next forward movement the surface 21 moves the plate 11 another step to the right, thus bringing the projection 12 into the path of the hundreds keys. In the modification shown in Figs. 3 and 4, the feeling-device 12 is carried by a sliding plate 40, moved step-by-step to the right by the armature of a magnet 33. The depression of the units key 30 closes a circuit from the battery 36 through a contact 35 on the feeling-device 12, and through the magnets 33, 37 in parallel to contacts 31, 30 and earth. The magnet 33 (1) moves the plate 40 one step to the right, bringing the feeler 12 beneath the thousands keys; (2) closes a contact 41, which earths the b-lead and makes the circuit of the magnets 33, 37 independent of the contact 30; (3) connects an interrupter 18 to the a-lead and to the escapement magnet 44. The magnet 37 attracts a sector 45 which rotates the ratchet 47 under the control of the magnet 44. Each time the interrupter 18 earths the a-lead, the feeler 12 is moved forward one step, until it engages a depressed key, when the contact 35 opens the circuit of the magnets 33, 37, thus disconnecting the interrupter 18 and restoring the feeler 12 to its normal position. When the group selector has found an idle trunk, the b-lead is again earthed, energizing the magnets 33, 37 as before. The plate 40 is moved another step to the right by the magnet 33, and the process is repeated under the control of the depressed hundreds key, and so nn.