Patent GB-543876-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M15/08
Filed: 1940-11-13
Abstract: 543,876. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd., TAYLOR, R., and BAKER, G. T. (Corner, A. C., in part). Nov. 13, 1940, No. 16423. [Class 40 (iv)] For assistance in accounting, a ticket or card is made out each time a subscriber's meter registers a predetermined number of call units under the control of contacts associated with the meter. The predetermined number, conveniently termed a block unit, may be 10, 20, 50 or 100 according to the amount of traffic on the particular line. The tickets are punched or printed with the number of the subscriber and a number representing the block unit, and they are sorted automatically or manually for the purpose of preparing the subscribers' accounts. The meter MTR may be of a simplified type having only units and tens wheels, and the momentary closure of contacts mtr by the latter wheel causes the association of the line with common recording apparatus, the operation being initiated by the striking of an individual neon tube NT in series with a common start relay CR, the discharge of the neon tube being maintained independently of contacts mtr by a voltage supplied over resistance YB. The block unit may be stored alternatively by a locking relay or a condenser. A metal rectifier MRA across relay CR ensures that it receives the same current irrespective of the number of neon tubes taking current therefrom. Each group of 100 lines is served by a 25-point finder SF with two sets of staggered wipers and 25 of these finders are associated with a finder PF to cater for 2500 lines. Four such units are necessary in a 10,000 line exchange. On the operation of relay CR, the finder PF hunts for a group marking, whereupon the appropriate finder SF hunts. By the discharge of the tube NT the potential on the wire 12 is rendered much less negative than that which would otherwise be applied over resistance YB, and a pair of valves VA, VB are suitably biased to respond to such a change of potential. The response of one of the valves results in the operation of relay KA with or without KB, and a potential is fed back to extinguish the tube NT. A marking switch S now takes up the same position as SF, whereupon relay NS energizes to start the transmission of information. The control switch PC first moves to a starting position corresponding to the particular 2,500-line unit, whereupon relay CS pulls up, and the switch advances under the control of relays IS. IP through a series of positions in which the information is transferred to the punching magnets. The tens thousands digit of the subscriber's number, which is common to the exchange, is determined at a cross-connecting frame TTF, the thousands and hundreds digits by the switch PF and the tens and units digits by the switch S. Cross-connections are made to the banks of the finders SF in accordance with the block units allotted to the various subscribers, and a corresponding digit is punched after the subscriber's number. Finally, relay RR pulls up and terminates the recording operation. Instead of a line being connected to the recording apparatus each time a block unit is completed, connections may be made thereto at regular intervals, the completion of the block unit being indicated by the closure of contacts associated with the meter. To guard against a unit being recorded more than once, the contacts may be restored after recording has taken place, preferably by advancing the meter by means of a definite number of artificial impulses, which would have to be allowed for in assessing the value of the block unit. Other methods may be employed for identifying the subscribers' lines, for example, the method in which potentials are applied to the lines at various instants in a cycle as described in Specifications 525,902 and 539,823. The recording apparatus may be located at the central exchange of an area, in which case it could be associated with any one exchange over a finder, and information could be sent thereto in code. Instead of the tickets being made out automatically, the information may be given by means of a call indicator to an attendant who makes out tickets manually. Mounting of apparatus.-The individual neon tubes NT and resistances YB and the finders SF are preferably mounted on the final selector racks and the rest of the apparatus on the alarm equipment racks. In the case of new exchanges the meters may be mounted on the line finder or line switch racks instead of on separate meter racks, so that a single lead will extend from each meter contact via the intermediate distribution frame to the neon tube.