Patent GB-511189-A (GB)
Title: Improvements in and relating to telephone installations
IPC: H04M15/10
Filed: 1938-01-13
Abstract: 511,189. Automatic exchange systems. TELEFONENBAU UND NORMALZEIT GES. Jan. 13, 1938, No. 1234. Convention date, Jan. 14, 1937. [Class 40 (iv)] In an arrangement for metering in accordance with the connection obtained, the duration of conversation and the tariff in force (e.g. day or night), impulses are transmitted over a selected zone lead by a common transmitter comprising a cam disc for each tariff, each disc having different series of cams for different periods of conversation, e.g. a 3-minute initial period and subsequent 1-minute periods, means being provided whereby the appropriate series are effective during the respective periods. The impulses. may, as in the arrangement shown, be metered at the end of each period, or they may be stored and transmitted to the meter at the end of conversation, Fig. 2 (not shown). ,The circuit shown in Fig. 1 associated 'with an outgoing repeater comprises an individual time switch DZ and zone switch DK, and common impulse generating devices ZS. When the circuit is seized, relay C energizes and impulses repeated forward by relay A (not shown) are also repeated to DK. If the zone is determined by more than one digit further zone switches are provided. On relapse of series relay V, G pulls up to open the circuit of DK. When the called party replies, B pulls up over the b wire, locks and connects magnet DZ of the time switch to a 10-second interrupter 10, Relay Z(i) operated over the 1st contacts of dz1, sends a metering impulse over the 4th wire and operates E which holds and connects battery to Z(ii) in preparation for the transmission of zone impulses at the end of 3 minutes. The impulse generators each comprise a pair of impulse cams Nt, Nn for day and night tariffs respectively and each cam comprises a group nt1, nn1 for impulse transmission after 3 minutes and a group nt2; nn2 for transmission after succeeding 1 -minute intervals. As impulses are required to be sent out by nt2, nn2 at repeated intervals, whereas nt1, nn1 only send once, a cam Nst1 on the same shaft as the impulse cams is arranged to replace ground on the impulse springs by battery when nt2, nn2 engage the impulse springs, the battery connection to Z(ii) being changed to ground after the first group of impulses have been sent so that the first group is subsequently ineffective. A switch U is provided to change over from the night tariff cam Nn, to the day cam Nt. When time switch DZ reaches contacts 2, Z, falls back and a circuit is prepared for T which operates when start cam Nst, on the same shaft as the others, operates springs st. Relay T shortcircuits its winding T(i) to busy the impulse generator and completes the circuit over the zone switch so that Z(ii) is impulsed by group nn1 (assuming switch U in the "night" position as shown) and sends metering impulses over the fourth wire, group nn2 being ineffective. The cam discs make approximately one revolution per second. The operation of T. also steps DZ immediately to contacts 3 in which T is held over high resistance Wi1 and the two left-hand springs of st until st runs off the part y2 of cam Nst whereupon T relapses to disconnect metering relay Z(ii). Afcer 2 mins. 50 secs., relay W operated over dz1 in position 18 connects a warning signal WS to line and steps DZ to 19. Relay W releases E and then falls, wiper dz1 being replaced by dz2 on operation of F(ii) which holds over (i). Relay Z(ii) is now connected to ground in readiness for receiving battery impulses from group nn2. When DZ reaches contacts 20, T is re-operated by cam Nst in the start position, connects the metering lead to Z(ii), holds until DZ moves to contacts 1 and falls back, a similar operation occurring when DZ reaches contacts 6 and 13 so that metering is effected at intervals of one minute. Release may be effected after 6 or 12 minutes by means not shown.