Patent GB-672689-A (GB)
Title: Automatic multiple dialling device
IPC: H04M1/274
Filed: 1948-12-22
Abstract: 672,689. Impulse transmitters. SOC. CIVILE DES BREVETS O.B. Dec. 22, 1948 [Dec. 22, 1947], No. 33050/48. Class 40 (iv). In Fig. 1, three separate telephone numbers each comprising three letters and four digits may be manually set up on three identical series A, B, C of seven drums 3 projecting peripherally through a panel 1 and engraved with letters and digits. Each drum of a series is connected through a spring pawl 13 (Fig. 5) to a ratchet 11 fast to a shaft 8 which passes axially through the series and is rotatable by a motor MA (or MB or MC) to operate an impulse sender EA (or EB or EC) against a return spring normally urging the shaft to a rest position in which an abutment 9 is arrested by a stop 10 (Fig. 2). The ratchets permit manual undirectional rotation of the drums to positions at which the required ciphers are displayed, and projecting drum abutments 12 are correspondingly positioned relatively to the armatures of an A, B, or C range of electromagnetic relays 15, each of which is selectively energizable to attract its armature 16 into the path of the corresponding drum abutment 12 so as to arrest its rotation and complete an electrical circuit operative to de-energize the appropriate drive motor, so that the associated impulse sender is driven back to rest by the return spring from a position corresponding to the cipher set on the drum, so as to transmit the appropriate impulse train to line by operating contacts 47 in a telephone instrument (Fig. 15) comprising a receiver 43, microphone 44, hook switch 45, bell 46, a bell or buzzer device 48 indicating that a called number has answered, and a line switch L cyclically operated by cam 17 to over ride the hook switch and insert the answering signal instead of the bell. After the required numbers have been set up, the green buttons 4 corresponding with the A, B, and C drum series are depressed, and connect the drum drive motors MA, MB, MC and the A, B, C relay banks 15 in circuit through contacts a, b, c, d, e, f and a<SP>1</SP>, b<SP>1</SP>, c<SP>1</SP>, d<SP>1</SP>, e<SP>1</SP>, f<SP>1</SP> (Figs. 14, 14a), close the circuits of the A, B, C green pilot lamps 6, and start the timing motor MM which drives cams 17, 18 at one revolution in two minutes and cams 19 to 26 at three revolutions per minute. Cam 17 closes the line switch L of the telephone instrument (Fig. 15) to connect the answer indicator 48 to line, and closes a first contact FR in the circuit of the A, B, C red pilot lamps 7 for sixty seconds; cam 18 impulses the contacts 30 every twenty seconds to step the ratchetoperated distributing switch 31 one position; cam 19 impulses contacts W seven times every twenty seconds; and cams 20-26 successively close contacts 20<SP>1</SP>-26<SP>1</SP> to cyclically energize each of the A drum stop relays 15 once per twenty seconds. Initially the switch 31 is in its first position and contacts 38, RA and FRA are closed by its cams to complete the circuits of the motor MA, the A bank of drum stop relays and the A red pilot lamp 7, and the initial impulse of contacts W operates relay RM which holds through the released contacts of relay RF to energize the motor MA to drive the A shaft 8. The first relay 15 has meanwhile been energized through contact 20<SP>1</SP>, and its armature 16 engages the abutment 12 of the first drum to arrest it and close contacts F to operate relay RF, release relay RM and stop the motor MA, so that the shaft 8 is returned by the spring to its rest position and pulses out the cipher set on the first drum. The following impulse of contacts W restarts motor MA, the second relay 15 is now energized through contacts 211 and the second cipher is pulsed out as before, until after twenty seconds, all the seven ciphers of the A drum series have been pulsed out. Cam 18 now pulses contacts 30 and steps the distributing switch 31 by one position, opening contacts RA and 40 to disconnect the motor and relays, while the A red pilot lamp 7 remains alight during the period of forty seconds for awaiting a reply to the first call. In the absence of a reply, cam 17 opens contacts FRA to extinguish the red pilot lamp 7 and opens the line switch L so that the instrument may operate normally on incoming calls. After one minute the line switch L and switch FR are again operated, and meanwhile switch 31 has been impulsed to close contacts 39, RB and FRB to light the B red pilot lamp 7 and connect the motor MB and relay bank B to pulse out the ciphers of the second number by a similar cycle. After forty seconds wait for a reply, and a one-minute interval for normal incoming calls, the third number is pulsed out. If the green button of a drum series is not operated, that series is disabled and the number set up thereon is not pulsed out. When a called number arrives during the waiting period, the answer indicating device 48, which has been connected to line by the line switch L, operates, the subscriber lifts his receiver, and presses the red button 5 of the drum series in action, indicated by the illuminated red pilot lamp 7, to automatically reset the corresponding green button 4 and extinguish the green pilot lamp 6, so that the drum series is available for a new number to be set up. Lifting the receiver at any time, whether to answer or originate a call, closes contacts Y to operate relay RY to arrest the timing motor MM after a delay until cam 17 has rotated to a position at which line switch L is inoperative and contact X is closed. The instrument now functions normally and at the end of the conversation the apparatus may be restarted to call the succeeding number. The motors MA, MB, MC are replaceable by a single motor driving three magnetic clutches energized by the appropriate circuits.