Patent GB-351602-A (GB)
Title: Improvements in and relating to impulse senders for use in automatic telephone systems and the like
IPC: H04M1/40
Filed: 1930-04-04
Abstract: 351,602. I m p u l s e transmitters. MACADIE, D., 109, Bowes Road, Palmers Green, London. April 4, 1930, No. 10775. [Class 40 (iv).] In a keyboard impulse sender, the keys effect selective setting of a ratchet wheel, and impulses are generated during a follow-up movement under control of a coiled spring which is tensioned during the setting movement, a fixed " lost-motion" period being provided to ensure the interdigital pause. The keys d<3>, which are arranged in two series of five in the manner shown, are pivoted at the rear of the apparatus, and in their downward movement act on the upturned edge of a lateral tapering plate e<1> pivoted at the front of the apparatus, the bearing plates d<5> on the key levers being staggered to give different angular movements to the plate e<1>. Restoring springs d<4>, f are provided for the key levers and the plate e<1>. The selective movement is communicated to a ratchet wheel g<3> carried by a sleeve k<3> on the shaft h by means of an arm e<12> on the plate e<1> which is linked to a pivoted lever g carrying the driving pawl g<1>. To prevent overthrow, a detent g<4> normally engages the ratchet g<3> and is withdrawn when the key lever is in its lowest position in engagement with a U-shaped arm g<10>. A dashpot can be used instead for this purpose. Near the ratchet g<3> is mounted a disc j having pins j<1> disposed in apertures near the periphery and capable of lateral movement against friction exerted by a spring j<3> occupying a peripheral groove merging into the apertures. These pins normally project on the side of the disc adjacent to the ratchet, and a selected one is adapted to be moved to project on the opposite side by means of a striker arm l which is connected to the ratchet g<3> by a blade spring l<5>. A plate m, Fig. 7, embracing the sleeve k<3> and connected to the frame by a blade spring m<1> has a bevelled end m<1> which co-operates with the turnedover end n<1> of an arm n integral with the lever g. As the arm n moves to and fro, the spring m<1> is flexed and the plate m is finally released and strikes pins l<6> on the arm l, which in turn strikes the appropriate pin j<1> and moves it laterally. The rotation of the ratchet g<3> tensions a coiled spring (not shown) which couples the sleeve k<3> to a sleeve k carrying a plate k<4> on which the impulse-generating mechanism is mounted, the plate k<4> being held by the abutment of a pin o<17>, Fig. 8, thereon against a pawl o which engages a ratchet ring p mounted in ball bearings in the pin disc j and capable of slight rotation under control of a detent p<2>, Fig. 11, which bears against spring contacts p<4>. The pawl o normally engages a pivoted stop o<4> on the ratchet g<3>. The lateral movement of the striker arm l by means of a blade spring o<8>, Fig. 9, withdraws the pawl o from the ratchet ring p allowing the latter to move in an anticlockwise direction, Fig. 8, due to the resilience of the contacts p<4>, which close and cut out the telephone instruments. The pawl o flies round under the influence of a spring o<1> until it again strikes the stop o<4>, which has meanwhile been rotated by the spring o<6>. The plate k<4> in turn rotates under control of the coiled spring, and the additional pressure when the pin o<17> strikes the pawl o is sufficient to return the stop o<6> to its normal position. This small movement is imparted to the ratchet ring p with which the pawl o is again in engagement and causes the contacts p<1> to be reopened. The plate k<4>, Fig. 12, carries a pinion (not shown) engaging the toothed inner periphery j<5> of the pin disc j and driving a governor (not shown) and an interrupter wheel k<6> which controls impulse springs k<7> connected to the line wires through slip-rings k<9> and wipers k<10>. The arrangement is such that the rotation of the interrupter wheel k<6> includes lost motion corresponding to five impulses to ensure the interdigital pause. The springs k<7> are also controlled by a rocking lever k<11> on the plate k<4>, the other end k<12> of which is adapted to be engaged by the operated pin j<1> of the pin disc to hold the springs closed during the lost-motion period independently of the interrupter wheel k<6>. The lost-motion period may take place partly before and partly after the impulses are sent. A curved arm on the plate k<4> returns the operated pin j<1> to normal after it has acted on the lever k<11>. The Provisional Specification describes other arrangements which differ mainly as regards the manner in which the lost-motion of the impulsegenerating mechanism is obtained.