Patent GB-250332-A (GB)
Title: Improvements in or relating to impulse transmitters particularly for use in automatic telephone systems
IPC: H04M1/274
Filed: 1925-01-10
Abstract: 250,332. Automatic Telephone Manufacturing Co., Ltd., (Automatic Electric Co.). Jan. 10, 1925. Impulse transmitters for automatic exchange telephone systems. Relates to impulse transmitters of the kind adapted to transmit a plurality of trains of impulses in response to a single setting operation. Two modifications are described in both of which the finger stop or stops are movable, the rotation of the finger-hold dial prior to the engagement of a finger stop, operating mechanism which sheets a particular cam disc to determine the impulse trains and the further joint rotation of the dial and stop winding up the impulse generating mechanism. In the first modification a pawl co-operates with the selected cam disc to bring the impulse springs into the path of the impulse cam for periods corresponding to detents cut in the periphery of the cam disc. According to the second modification, the impulse springs generate a fixed number of impulses and a mechanism co-operates with the selected cam disc to short-circuit them during predetermined intervals and thus split the impulses up into trains of the required length. First construction, Figs. 1, 2, 2<A>, 3, 6, and 7. The rotation of the dial 1 before the finger stop 42 is encountered causes a pawl 10 to select a particular cam disc 6<1>. The dial and finger stop are then looked together and rotated a complete revolution, during which the impulse generating mechanism is wound up. During the joint return of the dial and stop, the pawl 10 co-operates with the disk 6<1> to bring the impulse springs 76, 77 into the path of the impulse cam 99 for periods corresponding to detents cut in the periphery of the disc 6'. After the stop reaches normal, the dial is unlocked and continues alone to normal, restoring the pawl to normal during its return. During the setting operation prior tn the finger stop 42 being encountered, the dialcarrying shaft 68 is rotated. A gear wheel 92, Fig. 3, loosely mounted on the shaft 68 but connected to it through a spring 127 which at this time merely acts as a connecting link, rotates a pinion 91 fixed to a gear 102 in mesh with pinions 111, 103. The pinion 103 turns a worm 72, Fig. 2, which raises a pawl 10 slidable on a vertical guide 58, to a position opposite to the appropriate cam disc 6<1>. The finger stop 42 is mounted upon a hub 126, Fig. 7, to which are fixed two gears 25, 27 and which has mounted upon it a pivoted member 37. The stop 42 is normally spring-pressed against a downwardlypointing arm 39 on the member 37, which arm is in turn pressed against a stop 30 on the mounting. As soon as the finger stop 42 is moved off normal, the member 37 is rotated on its pivot in a counter-clockwise direction under tension of a spring 46 until its upturned end 41 engages a toothed wheel 43 fixed to the dial, - thereby locking the dial and finger stop together. At the same time a downwardly-projecting pin 31 on the finger stop 42 moves away from an arm 55 pivoted on the mounting plate 3. The arm 55 is thus permitted to rotate under tension of a spring 56 and moves a downwardly-extending part 40 away from a stop 36 on a pinion 35 fixed to a shaft 34 carrying the impulse cam 99 : in this manner a lock is removed from the impulse cam. Directly the gear 25 begins to rotate with the finger stop it moves a pin 32, Figs. 1 and 2A, away from an arm 14 which then permits an arm 15 to be moved by a spring 101 into the path of a cam 21 on the shaft carrying the disc-choosing worm 72; this locks the gearing 72, 103, 92 so that during the further rotation of the dial with the finger stop the spring 127 is wound up. The finger stop is rotated a complete revolution, on the completion of which a pin 29, Fig. 1, on the hub 126 causes a pivoted arm 16 to remove a detent 18 from a notch in the bracket 58 carrying the disc pawl 10. The bracket 58 is then rotated by a spring 114, Fig. 3, thereby bringing the pawl 10 into engagement with the selected disc 6<1>. The further rotation of the pawl 10, when a detent of the disc 6<1> is engaged, allows an arm 78, Fig. 6, to move the impulse springs 76, 77 into the path of the impulse cam 99 and closes springs 74, 75, which shunt the transmitter and receiver during actual impulse transmission. On the release of the dial, the finger stop and dial first complete a whole return revolution together under power stored in a spring 66 during the forward movement through the medium of gears 57, 50. During this return movement the cam disc assembly 71 is rotated a complete revolution through gearing 57, 8, and the impulse cam 99 is rotated through gearing 25, 104, 35, the speed being controlled by a governor 64 operated through a worm wheel 51 on the cam shaft 34. As the pawl 10 drops into the detents in the selected disc 6<1> the impulse springs 76, 77 are moved into range of the cam 99 and trains of impulses are sent. Just prior to the finger stop reaching its normal position the pin 32 unlocks the positioning mechanism of the pawl 10, the pin 29 causes the bracket 58 to rotate and disengage the pawl 10 from the disc assembly, and the pin 31 locks the gearing which rotates the impulse cam 99. When the finger stop 42 reaches its normal position the arm 39 on the member 37 engages the stop 30, and causes the end 41 to disengage itself from the gear 43, thereby unlocking the dial from the finger stop and allowing the former to return to normal alone under the tension of a spring 68<1> which is wound up during the forward movement of the shaft 68. The pawl-positioning gearing 72, 103, 92 now returns the pawl 10 to its normal position, where a pin 135 on the dial 1 engages a stop 44 on the finger stop 42, the return of the dial being under control of a governor in a casing 100 operated through gearing 92, 103, 111. A leather bumper 45 is mounted on the stop 44 to act as a cushion. Second construction, Figs. 8, 10, 11, 12, 16, 18, and 19. In this modification the movement of the dial prior to the engagement of a finger stop selects a cam disc as before, but two finger stops are provided on the finger stop bar 225, which is always turned through 180 with the dial. On the return of the bar 225, the impulse cam 266, Fig. 18, generates a fixed number of impulses which are broken up into trains by mechanism which co-operates with a selected cam disc to short-circuit the impulse springs during predetermined intervals. A semicircular cam disc 290<1> is provided for each subscriber, alternate discs of the assembly being staggered on opposite sides of a common diameter : this necessitates a corresponding arrangement of the subscribers' finger holes on the two halves of the dial. The first subscriber's finger hole 1 cooperates with the upper finger stop, Fig. 8, and as the short-circuiting mechanism is normally opposite the first cam disc the hole 1 is so positioned that no prior movement of the dial takes place; the second party's hole 2 is arranged with respect to the lower finger stop so that the dial makes the prior movement of 6 which is required to raise the shunting mechanism opposite the second disc; the third subscriber's hole 3 is positioned 12 from the upper stop, the fourth subscriber's hole 4, 18 from the lower stop, and so on. The shunting mechanism is mounted upon a U-shaped bar 327, Fig. 12, which rotates in a sleeve 223<1> on the mounting plate 202, and between the legs of which are journaled a worm 234 and a shaft 233. A bar 231, Fig. 19, carrying at each end a short-circuiting pawl 250, 251, is mounted on a hub 232, Fig. 12, which is caused to travel along the shaft 233 through the medium of a projection 281 engaging the worm 234. The upper leg of the bar 227 is formed with a shaft housing 229 which projects through a semi-circular slot in the plate 202 and through holes in a gear wheel 224 and the finger stop plate 225 which is fixed to the said gear wheel. A power spring 221, one end of which is fixed to the plate 202 and the other end to the gear 224, tends to rotate the bar 227 counter-clockwise, but this is normally prevented by the housing 229 engaging one end of the semicircular slot in the plate 202. The rotation of the finger hole dial 245 prior to the engagement of a finger stop winds up a spring 238, rotates the worm 234 through the gear train 228, 237, 230, 236, 235, and causes the bar 231 to be raised opposite the appropriate cam disc. The dial and the stop bar 225 are then rotated together half a revolution, during which the power spring 221 is wound up the mechanism carried by the U-shaped bar 227 is turned through 180, and a shunting pawl 250, 251 is brought to the beginning of the selected cam disc. As soon as the stop bar 225 is moved from normal, a dog 242, Fig. 16, on the bar 227 is moved away from a pin 243 on the plate 202 and is then spring- urged into engagement with a cam 235' integral with the worm 234, thereby locking the cam disc selecting mechanism. During the forward movement of the stop bar 225, due to a pawl- and-ratchet connection between gear 216 and pinion 217, the impulse cam 266, Figs. 10 and 18, is not rotated, but on the return movement a fixed number of impulses is generated by the springs 275, 276 through the train of gearing 224, 217, 216, 219. A governor 268, Fig. 11, is also rotated through the gear wheel 218 and pinion 215; the governor is connected to its shaft through a ratchet and pawl, so that when the pinion 215 is stopped the governor is free to rotate under its own movement. When the finger stop bar 225 reaches normal the detent 242 is removed from the cam 235<1>. unlocking the disc-selecting mechanism and permitting it to return to normal during the return to normal of the finger dial. The impulse train is split up into seven digits by the raised parts on the selected cam disc in the following manner. Three springs 252, 253, 254, Fig. 19, controlled by the shunting pawls 250, 251, are mounted on the bar 231 and connected to