US1819683A - Telephone system - Google Patents

Description

Aug. 18, 1931. K. KQPARSSQN 1,319,683

Tamradna. SYSTEM Filed June 9, 1930 INVEN {L .87 hum/ o Patented Aug. 18, 1931 KNUT LARSSON, OF STOCKHO'LM, SRTEDEN,

.kSSIGNOB. TOTELEFONAKTIEBOLAGET L. M.

ERICSSON, OF STOCKHOLM, A COMPANY OF SWEDEN TELEPHONE SYSTEM Application filed June 9, 1930, Serial No. d60,017,-and. in Sweden June 21, 1929.

in telephone plants 01 system the subscribers lines are usually provided with so called line and cut-ofli relays to control the call circuit and, in certain cases,

5 also the call meter circuit. The cost of said relays makes up a considerable part of the total costs for a telephone exchange, as

counted per subscribers line, for which reason any simplification in the construction of such relays may considerably influence the economy of the entire plant.

The present invention has for its object to reduce the cost of manufacture of the line and cut-ofii relays by a reduction in the number of contact springs of said relay. This is brought about according to the invention by that those contact springs of the cut-off relay, which control the circuit extending over the test wire, are adapted to be actuated by the 29 line relay when the latter is energized.

The invention will be more closely explained with reference to the accompanying drawings, on which Figure 1 shows a known arrangement of the line and cut-oil. relays and the appertaining circuits whereas Figure 2 shows a corresponding arrangement according to the invention. Figure 3 discloses an example of the constructional features.

Figure 1 shows a subscribers line of which the two branches a, I) together with the appertaining test wire 0 are connected to fixed contacts alc, bk, 07a in the contact field of a call finder. To the subscribers line belongs the line relay LB, 2. cut-on relay BR and a call meter SM.

Upon a call, the line relay LR is energized in known manner over the subscribers line, a call finder being started through the intermedium of the starting relay SR the circuit of which is closed over the contacts 8, 9 of the line relay. At the same time the cut-off relay BB is connected to the test wire 0 over contacts 10, 11 of the line relay besides which the call meter SM is disconnected from the test wire 0 at the contacts 12, 18. When the call finder finds the calling line a circuit is closed over the test wire 0 and the contacts 10, 11 through the cut-off relay BR which is energized and disconnects the line relay the central battery LR at the contacts 1, 2, 3, 4c. The line'relay LR- is deenergized and opens the circuit of the relay SR. The cut-oil relay BR remains thereupon energized over the contactsf), 6

whereas the call meter now is disconnected at the contacts 6, 7.

Call'metering may also be brought about in known manner by connecting the wire 0 to the negative pole of the battery, the cutoff relay BR being short-circuited. When the relay BR for this reason is deenergized the call meter SM is connected into circuit to the test wire over the contacts 6, 7 the call meter being then actuated.

The circuit arrangement shown in Figure 1 may according to the invention be simplified in a manner shown in Figure 2. The group of contact springs 5, 6, 7 is here so disposed that it may be actuated by both the cut-0E relay BR and the line relayLR. Hereby the contact spring group 10, 11, 12, 13 marked in Figure 1 by a dashed and dotted circle becomes superfluous at the same time as the circuits are simplified. The same contact spring couple 5, 6 over which the cutoff relay is connected to the test wire serves namely also to lock the cut-off relay after theline relay LR is dc-energized. Further, only one contact spring couple 6, 7 is required to control the circuit of the call meter SM. For the rest, the arrangement is the same as in Figure 1 and the operation is also sub stantially the same. When the line relay LR is energized the contact spring group 5, 6, 7 is actuated in such a manner that the cut-oil relay BB is directly connected to the test wire, whereas the call finder SM is disconnected. As said contact spring group is adapted to be actuated also by the cut-0E relay, said group will be held in the actuated position by the relay BR even after the line relay LR has been deenergized. The call metering then takes place in the same manner as above by short-circuiting the relay BR over the test wire, the call meter SM then obtaining a current impulse over the contacts 6, 7.

Figure 3 shows an example of the disposition of the contact springs of the relays LR and ER. The contact s ) ring group 8, 9 and 1, 2, 8, 1 are so dispose that they are actuated only by the relay armatures LA and BA respectively Whereas the contact spring group 5, 6, 7 is disposed between said groups so that it may be actuated by both armatures.

5 I claim:

1. In a circuit arrangement for telephone plants a subscribers line, line and cut-oft relays connected to said line, a number of contacts appertaining to said cut-off relay and 1 controlling,the circuit extending over the test Wire, and means to actuate said contacts by the line relay when the latter relay is energized.

2. In a circuit arrangement for telephone 1 plants, a subscribers line, line and cut-ofi' relays connected to said line. a number of cont'acts appertaining to said cutoff relay, means to actuatesaidcontacts' by the line relaywhen the latter relay is energized, means 2q to' c'onnect. the cut-off relay to thei test Wire "over contacts Which are actuatedbythe line relay when it is energized, and means to lock sziidbutpfirelaycyer thesame contacts When it islene rgiz ed'o'ver the test wire.

3.;In a circuit arrangement according to "claim 2, means to disconnect the call meter from and connect itto thetest Wire over one and the same breakcontact actuated both bythe line relay and the cut-off relay.

In ,te stimonyrwhereofl ,afllx my signature.

4 KNUT LARSSON.

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