Patent GB-350912-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1930-03-15
Abstract: 350,912. Automatic exchange systems. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street Chicago, U.S.A. March 15, 1930, No. 8453. Convention date, April 5, 1929. [Class 40 (iv).] In a register sender for use in telephone systems wherein digits transmitted from an operator's keyboard are successively recorded upon groups of register relays, the relays control the marking of leads associated with a step-by-step impulse sender singly or in different combinations according to the digit registered. In the arrangement shown when the operator sets up his desired number following seizure of the register set RS and consequential earthing of the test lead 175, successive digits are recorded upon the relay register sets DR1 .. DR4, the relays A .. D in each set being operated singly or in different pairs according to the digit registered. Energization of the relays is effected from the keyboard over leads 171 .. 174 and transfer of these leads to successive registers is effected by relays 205, 215, 225, 235, which lock up in series with the operated relays in the register sets. The register relays control the marking of two sets of leads 31 .. 34, 41 .. 44 connected in characteristic manner to the banks 22, 23 of an impulsesending switch S. Operation of the final transfer relay 235 earths lead 243 which causes switch over of leads 171, 172 from the key-set to the automatic stepping switches and operation of the stepping magnet 303 of the sender S in series with interrupter 304. Following the first step of the switch S, relay 306 is energized over wiper 21 to open a bridge across the impulse leads 241, 242, which are connected to leads 171, 172, and impulses are transmitted at contact 301 of the stepping magnet 303 during further operation of the switch. Impulses are sent until the switch arrives in a position characteristic of the marked leads in the group 31 .. 34, energization of the relay 305, which opens the driving circuit of the stepping switch, being dependent upon simultaneous closure of circuits over both wipers 22, 23, earthed contacts being provided in bank of wiper 22 to account for single marking. In this manner, a number of impulses is sent out corresponding to the particular relay or combination of relays energized in the register DR1. When relay 306 is energized at commencement of impulsing relay 206 is energized over its lower winding and prepares a locking circuit to lead 175. At the termination of impulsing, the stepping switch is automatically driven to a subnormal position in the middle of the banks over a circuit including self-interrupting contacts 302, contact of relay 305 and wiper 21 and relay 306 is released, relay 206 consequently being fully energized to transfer lead 244 to switching relay 216. Release of relay 306 also releases 305, and stepping of the switch S is resumed over the second half of the contact bank to send a number of impulses characteristic of the setting of register DR2 which is associated with leads 41, 42 in a manner similar to that described above. Upon the termination of the second digit relay 216 is operated to release relays of the registers DR1, DR2, and energize relay 11 which re-marks the groups of leads 31 .. 34, 41 .. 44 in accordance with the settings of registers DR3, DR4, and corresponding series of impulses are transmitted during a second cycle of operations of the sender S. At the end of the fourth digit relay 236 is operated to remove earth from lead 243 and cause release of the sender. If desired, three relays in the registers may be energized in combination for particular digits, an additional wiper associated with a relay governing the operation relay 305 being provided. In a modification, each control wiper of the sender may be connected to a test relay and relay 305 operated in a local circuit through series connected contacts of all the test relays. In a further arrangement, the contacts of the register relays may be connected by four conductors to single bank sections for each wiper of the sender, the transfer relays 206; 216, 226 having additional contacts in circuit with the four marking leads.