Patent GB-779833-A (GB)
Title: Telephone system using single-motion numerical switches
IPC: H04Q3/00
Filed: 1954-04-26
Abstract: 779,833. Automatic exchange systems. AUTOMATIC ELECTRIC LABORATORIES, Inc. April 26, 1954 [May 11, 1953], No. 11992/54. Class 40 (4). A single-motion group selector or final selector is advanced over unwanted groups to the start position of the wanted group concurrently with the reception of the corresponding series of impulses and with the aid of interrupter circuits for the switch magnet which extend over a control wiper and bank of the switch and, respectively, over a first start conductor multipled to contacts in said control bank corresponding to the start positions of oddnumbered groups, over a second start conductor multipled to contacts in said control bank corresponding to the start positions of evennumbered groups, and over additional connections to said control bank in the positions between said odd and even start positions, said first and second start conductors being made effective in turn, each on alternate impulses, by contacts of odd-even control means associated with the switch and governed by its impulseresponsive means while said additional connections are independent of the individual impulses. As shown, the invention is applied to a party-line final selector with two sets of wipers giving access respectively to odd- and evennumbered groups of lines. The odd-even control means comprises an auxiliary switch having wipers A1-3 driven by a magnet 60. The selector wipers are arranged in pairs, the two wipers of each pair being at 180 degrees to each other. Call from substation A to party-line substation B (Directory number "934"). Line switch 20 extends the calling loop to an idle final selector where line relay 110 and hold relay 120 are thereby energized. The calling subscriber A hears dialling tone from lead 48 and dials the first (party-selecting, digit "9." Relay 110 repeats the impulses to the auxiliary switch magnet 60 which steps its wipers A1-3 accordingly, closing off-normal contacts 65. A slow-releasing relay 160 is energized at the first release of relay 110 and holds until the end of the impulse series. Its release brings about the operation of relays 130 and 200 in a circuit over auxiliary switch wiper A3 in position 9. Relay 200 completes a homing circuit for the auxiliary switch magnet 60, and relay 130 reverses the connections of the ringing generator lead 56, thereby preparing to send ringing current over the negative wire of the wanted line. (If the first dialled digit is not " 9," relay 130 is not operated and the ringing potential is applied to the positive line wire.) Line relay 110 now responds to the second dialled digit "3," its first release bringing up relay 160 as before and also causing a two-step relay 170 to operate to its first step, closing its "X" contacts. Relay 170 completes its operation on the next energization of relay 110 and prepares circuits for the auxiliary switch magnet 60 and the final selector magnet 70. The second impulse causes the auxiliary switch to step to position 1 while magnet 70, by means of selfinterrupting circuits, initially over control wiper 77 and then over control wiper 76 (this latter circuit being independent of the condition of relay 110 during the impulse series), steps the selector to position 5. This is the start position of the 2nd group of outlets, the odd and even groups being arranged in staggered formation in the two sets of banks. Similarly the third impulse steps the auxiliary switch to position 2 and the selector to position 10, the start position of the 3rd group, the self-interrupting circuits for selector magnet 70 being completed initially over wipers 76 and A1 and subsequently over 76 only. The relapse of relay 160 at the end of the second digit brings up relay 190 to prepare circuits for a wiper-switching relay 180 (which operates over wiper A2 if the second digit is even) and for the selector magnet 70. Line relay 110 repeats the impulses of the final dialled digit "4 " to the magnet 70 which accordingly sets the selector to the wanted line. The first release of relay 110 brings up relays 165 and 160 so that relay 170 falls back and the busy relay 140 is connected to the test wipers CO1 and CO2. Wanted line found busy. Earth encountered on lead 99 by test wiper CO1 brings up busy relay 140 which connects busy tone from lead 58. When the calling subscriber hangs up, the switches go home and the equipment is released. Wanted line found idle. Failure of busy relay 140 to operate, in the absence of earth on test lead 99, allows relay 150 to operate in series with the cut-off relay of the wanted line following the delayed release of relays 165 and 160 after the cessation of dial impulses. Busying earth is thereby connected to test wiper CO1, and ringing tone is reverted from lead 42 while ringing current is sent from lead 56 over the negative line wire to call the wanted substation B. (The other substation C would be called over the positive line wire.) When B answers, ring cut-off relay 135 operates over the loop to switch through and bring up back-bridge relay 115. On release at the end of the call, busy relay 140 is energized in a circuit over offnormal contact 75 during the homing of the selector. Specifications 177,140 [Class 40 (iv)] 642,640, 754,855 and 771,793 are referred to.