Patent GB-191406209-A (GB)
Title: Improvements in or relating to Electrical Impluse Transmitters and the like.
IPC: H04M1/272
Filed: 1914-03-11
Granted: 1915-04-12
Abstract: 6209. Betulander Automatic Telephone Co., and Aitken, W. March 11. Impulse transmitters, for automatic exchange systems. The operations of a key-set or fingerhold device for the successive digits of a wanted number are recorded on a circle of retractable pins 4 on a wheel 1, the transmission of the line currents being deferred until the complete number has been set up. The pins 4 may be resiliently supported by the rays of a pair of sunflower stampings 2, 3, fixed in staggered relation at the back of the wheel 1. The different number keys depress a plate 10 to different extents, such that a pawl 9 on the plate 10 rotates the wheel 1 through three steps more than the number of the depressed key. During the last three steps, a pin 12 shifts a plate 13 so that a shoulder 14 presses back the three last pins. Thus, if No. 5 key is operated, the first five pins are left projecting through the wheel 1 and the next three are retracted, and if the No. 1 key is then operated, the next pin will be left projecting and the three succeeding pins will be retracted, and so on. The pins may be formed with shoulders, to hold themselves in the retracted position, or a circular wire locking-frame 5, Fig. 6, with a small gap opposite the shoulder 14, may be arranged behind the wheel 1. A disk 15, carrying the impulse springs 17, moves with the wheel 1 during the setting-operations. When these operations are completed, a rod 29 is lifted, either by a separate key R or by the removal of the telephone from its hook, and shifts a cross-piece 18, Fig. 6, to the right, disengaging a claw 24 from a recess 23 of a flanged ring 21 on the wheel 1. The disk 15, with which the cross-piece 18 is associated by pin-and-slot connexions 20, is thus uncoupled from the wheel 1, and turns back under the influence of a spring 16, the rate of movement being controlled by a governor. The impulse springs are now operated by the engagement of a finger 30 with the projecting pins 4, the three retracted pins between each two groups of projecting pins giving the necessary' pause between the sets of impulses. On regaining its normal position, the disk 15 is arrested by an arm 26 coming against a detent 27. The pressure of the arm 26 on the detent 27 releases the wheel 1, which is then returned to normal by a spring 8, and the coupling between the disk 15 and wheel 1 is restored. During the return of the wheel 1, the finger 30 gives freely on its pivot, so that no further impulses are dispatched. The retracted pins are released as they pass the gap in the locking-frame 5, or, if self-locking shouldered pins are used, they are released by passing a fixed pin which disengages them. The device may be operated by a finger-hold device instead of by keys. Fig. 10 shows a device of this kind with three staggered rows of number holes, any of which can be drawn by the subscriber's thumb up to a finger plate 39. The finger dial shown in Fig. 12 has the number holes spaced at increasing distances and each provided with a stop lever 41. The lever of the hole in which the finger is inserted turns slightly on its pivot as it leaves the fixed pin 42, and is thus brought into a position in which it will engage the next pin 42 to arrest the dial.