Patent GB-244202-A (GB)
Title: Improvements in and relating to automatic telephone instruments
IPC: H04M1/56
Filed: 1924-09-30
Abstract: 244,202. Sterling Telephone & Electric Co., Ltd., Dougan, R. H., and Penney, J. R. Sept. 30, 1924. Impulse transmitters. - Counting mechanism which during dialling sets up the number called, is associated with an impulse transmitter and is so arranged that one part of the movement of the dial establishes a driving connection with the appropriate digit wheel of the indicator, whilst the remainder of the movement causes the digit wheel to be rotated. In the arrangement shown, the counting mechanism is contained in a casing 29 and comprises a pinion 3 which meshes with a crown of teeth below the edge of the finger plate 1 of the impulse transmitter, and drives a shaft 4 through reduction gearing 5, 6, 7, 8. The shaft 4 carries two mutilated gear wheels 9, 10. The wheel 10 meshes with a pinion 12 connected to a one-way clutch 13 through which it rotates a long-toothed wheel 14, which can be geared with any one of the digit gear wheels 16 by means of a travelling pinion 15. The travelling pinion 15 is mounted upon a carriage 22, which moves along a rock shaft 21, and which carries two pawls 24, one of which engages teeth on the shaft 21, and the other of which engages teeth on a slider 20 movable in a slot in the shaft 21. The slider 20 is pressed to the left by a spring (not shown), whilst the carriage 22 is pressed to the left by a spring-pressed arm 23. The slider 20 is attached to a cam disc 19 coacting with another cam disc 18 secured to a pinion 11 mounted upon a shaft parallel with the shaft of the pinion 12, and meshing with the mutilated gear wheel 9. In operation, when the receiver is removed from its hook, the rock shaft 21 is rocked through the medium of an arm 30, thereby bringing its teeth and also those on the slider 20 beneath the pawls 24, and through an arm 27 rocking a plate 26 which permits spring- pressed holding pawls to engage the digit wheels 16. When the dial plate 1 is turned, during a first arc of movement corresponding to the arc a-b, teeth on the wheel 9 turn the pinion 11, causing the cam disc 19 and slider 20 to be pressed to the right. The slider 20 engages one of the pawls 24 and moves the carriage 22 one tooth space to the right, where the pinion 15 couples the long wheel 14 with the first digit wheel 16, and in which position it is held by the other pawl 24 engaging a tooth of the shaft 21. During the remaining arc of movement of the dial 1, the teeth of the mutilated gear wheel 10 turn the pinion 12 and through the clutch 13, long wheel 14, and pinion 15 rotate the first digit wheel 16 an amount corresponding to the number dialled. On the return movement of the dial, the cam 18 is turned back, the slider 20 returns to its left-hand position, and the pinion 12 rotates idly. When the next digit is dialled, the action is repeated, the carriage 22 being stepped another tooth and the pinion 15 brought into mesh with the second digit wheel. After the complete number has been dialled the carriage 22 cannot be stepped on any further and another number cannot be dialled until the indicator has been cleared. This is done by depressing the arm 30 either by hand or by the replacement of the receiver. The arm 30 turns the rock-shaft 21, thereby releasing the holding pawls 24 and causing the carriage 22 to be returned to its normal position by the arm 23, and through the arm 27 and rocking-plate 26 releasing all the holding pawls of the digit counter. Restoration may alternatively be effected electromagnetically by the opening of the line circuit, or positively by the return of the receiver. According to a modification, the pinion 15 may be moved by means of a threaded sleeve attached to it and passing through a longitudinally immovable but rotatable nut. The initial movement of the dial may be utilized to step the pinion 15 and the return movement to rotate it. The rotation of the digit wheels and/or the shifting of the driving connection may be effected by electromagnets.