Patent GB-441659-A (GB)
Title: Improvements in and relating to apparatus for the registration of signals in automatic telephone installations
IPC: H04Q3/00
Filed: 1935-01-18
Abstract: 441,659. Automatic exchange systems. ZOLLER, E., 48, Dorfstrasse, Zurich, Switzerland. Jan. 18, 1935, No. 1692. Convention date, Jan. 19, 1934. [Class 40 (iv)] Apparatus at a sub-station or the exchange for recording impulses from a subscriber's dial or other transmitter comprises an impulse relay I preferably shunted by a condenser, connected directly in the subscriber's line and controlling a slow release relay X which connects feeding battery B to the recording apparatus, Figs. 2 and 3, the feed being independent of the normal exchange battery. The apparatus comprises type printing arrangements also operated by single or repeated metering signals which comprise pulses of alternating current. A discriminating arrangement is provided to prevent the opparatus from being operated by breaks in the circuit due to switching operations &c. The apparatus may be used at the exchange for supervising a subscriber. Detailed operation. Impulse relay I pulls up when a call is made and slow release relay X makes a circuit for tape-feeding magnet V. The holding magnet S of the printer pulls up, holds itself and releases feed magnet V so that the tape is fed one step. The first impulse operates H which holds during the train and connects up the stepping magnet E to set the type wheel 2 of the printer in accordance with the impulses, cam 3 permitting off-normal contact w to close. When H falls back at the end of the train, printing magnet D pulls up and is released by R which also releases holding magnet S so that the printer restores to normal. Tape feeding magnet V again pulls up and re-energizes the holding magnet S which releases V to step the tape as before. When the remaining digits have been printed an A.C. metering impulse transmitted over the signalling wires in parallel on reply of the called party or on termination of conversation operates relay Z, the windings of which are differential, a change of phase being introduced, however, by condensers C2, C3 of different sizes. Z holds X and operates printing magnet D which prints the metering sign 31 (printer in normal position), the feed magnet moving the tape on as before. Repeated metering impulses are similarly recorded. The ink ribbon 18 is moved simultaneously with the tape 21. The subscriber may step the tape to a position where it can be read by opening key T whereupon assuming I and X are operated, S and V interact to step the tape. Discriminating against interfering impulses. Impulse relay I connects C4 across the line in series with choke L and on release connects the condenser across relay Y which has a normally open contact in place of or addition to that of X in the circuit of H. If the impulse is due to the dial, C4 will be charged before being connected across Y which will therefore close the circuit of H. If, however, the impulse is due to a temporary break in the exchange connecting circuits, C4 will not be charged and the impulse not recorded. Mention is also made of means for preventing a subscriber using dialled impulses to interfere with the recording of metering impulses.