US1889466A

US1889466A - Telephone plant

Info

Publication number: US1889466A
Application number: US549032A
Authority: US
Inventors: Crowe Douglas Cormack
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1930-07-26
Filing date: 1931-07-06
Publication date: 1932-11-29
Anticipated expiration: 1949-11-29

Description

Nov. 29, 1932. D. c. cRowE:

TELEPHONE PLANT Filed July 6, 1931 /NvN To@ D. C. @m w@- Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE DOUGLAS CORMACK CROWE, OF STOCKHOLM, SWEDEN, ASSIGNOR TO TELEFONAXTIE- IBOLAGET L. M. ERICSSON, F STOCKHOLM, SWEDEN, A COMPANY 0F SWEDEN TELEPHONE PLANT Application.v led .

Tuly

6, 193,1; Serial No. 549,032, and in Sweden July 26,1930.

The present invention refers to arrange ments for selective actuation of switching apparatus connected to a common line and is particularly applicable to telephone plants in which it is desired selectively to actuate cer- Y cuits.

tain apparatus in a group of switching apparatus over a single line by means of current impulses of different magnitudes and directions. The invention may also advantageously be applied to systems with so called party lines, the different subscribers sets being then provided with switching elements in accordance with the invention. In known systems of this kind it has been very difficult to .increase the number of subscribers to the desired degree while maintaining simplicity of circuit arrangements and construction in the telephone exchanger as well as at the subscribers positions. The desirability of central battery operation has then led to ditferent circuit arrangements with condensers at the subscribers positions. Said known circuit arrangements, however, require ringing current generators for a plurality of frequencies and doV not meet modern requirements with regard to the number of apparatus that can be connected to a certain line.

The present invention has for its objectto eliminate inconveniences of the above `'kind and consists substantially therein that each switching apparatus is provided with apolarized relay which is adapted to react only for current impulses of a certain kind and ywhich over two series-connected condensers is connected to earth, said polarized relay being arranged to shunt the one condenser over its resting contact and to cause the other condenser to be connected in parallel with the resistance over its operating contact. In this manner a circuit arrangement is obtained in which the condensers are charged Aover certain circuits and discharged over other cir- The invention will be more closely "described with reference to the accompanying drawing which shows asan example a telephone plant having eightv subscribers sets connected to a party line.

The upper part of the drawing shows'the party line with its branches a and b and with the subscribers sets l'to 8 connected thereto, only those parts being indicated which are necessary forillustrating the invention. The lower part of the drawing is intended to show those parts in the telephone exchange which are of interest for the explanation of the invention. For the sake of simplicity the signal device has been shown as a key set K but it is of course also conceivable to build the same of a number of relays which, for instance, may be actuated by means of ligure impulse series from other subscribers of the exchange orv from the party subscribers them` selves. The signal battery B is earthed at its middlepoint and has in addition thereto four terminals, namely V, +30 V, -30 V, -60 V. With these voltages eight different combinations may be obtained as will be seen from the following table. v

vous volts known manner to the party line, a calling circuit being then closed through elements of the apparatus 8 not shown on the drawing and through the line relay L, the latter relay then closing, over its operating contact land the Contact 2 of the relay B, a circuit 3 for the calling lamp AL which is thereby lit. The operator then connects herself to the party line by means of the jack J, the relay Bv being then energized over the circuit 4 and cutting oli the line relay and the plus-potential at its

contacts

5 and 6 respectively. The

operator is now able to communicate with the calling subscriber without being disturbed by any of the other party subscribers. After having been informed that connection with the subscriber 1 is desired the operator first pushes down the key 1 of the key set and thereafter the signal key SK whereby the signal is sent out on the party line. The signal consists partly therein that the b-wire is connected to the +3() V terminal of the battery over the circuit 6 and partly therein that the L-wire is connected to the i 60 V terminal of the signal battery over the circuit 7, a current impulse being thereby obtained tln'ough the polarized relay P, the condenser X, the resistance R and the resting contact 8 of the relay to earth. As at this instant the condenser Y is shunted the condenser X is charged and the relay P attracts its armature. The condenser X is then parallel-connected with an auxiliary relay H over the operating Contact 9 of the relay P, whereas the condenser Y is charged by means of new power from the a-wire. At the same time the condenser X is discharged over the relay H which attracts its armature and over its operating contact 10 connects the condenser Z to the b-wire in order to be charged. As soon as the condenser Y has been charged the relay P cannot any longer hold its armature attracted wherefore the latter returns to its normal position, the condenser X being then charged anew. Simultaneously with the relay P also the relay H is cle-energized and the condenser Z is discharged over the polarized alarm bell PR to earth. Said alarm bell is thereby brought to carry over its armature once whereafter the armature is restored by means of a spring controlling the same. The relay P is actuated again and the operation is repeated. The discharging circuit for the condenser X thus receives as many current impulses as the relay P wherefore the relay H vibrates in time with the relay P and consequently the same frequency of the toll of the alarm bell is obtained.

As will be seen from the drawing also the relays P and H of the subscriber 2 will vibrate and the appertaining condenser Z will be charged and discharged over th-e corresponding alarm bell PR. The alarm-bell of the subscriber 2 is, however, biased in the opposite direction to the alarm bell in the apparatus 1, and only the latter bell will therefore ring. It is, of course, also co-nceivablc to use positively controlled relays in place of alarm bells, the arrangements being then preferably such that the whole switching operation is carried out only once whereafter the armatures of the relays are locked in a suitable manner. The switching arrangement may then be used for establishing certain selecting operations. After the desired subscriber has been called up a talking connection is established in known manner. It

is only necessary that the operator lifts the key SK whereafter the talking circuits of the subscribers are fed from the exchange in known manner.

I claim 1. In a selective system a line, a number of marginal adjusted polarized relays each being connected between any of the branches of said line and earth over two series-connected condensers, means to actuate the polarized relays selectively by current impulses of different magnitudes and directions, means to shunt one of the said two condensers when the polarized relay is at rest, and means to connect the other condenser in parallel with a resistance when the said relay is energized.

2. A selective system as claimed in claim 1 the means to actuate the polarized relays selectively consisting of a signal battery having small capacity, earthed at its middle point and provided with a plurality of positive and negative voltage terminals.

3. ln a selective system a line, a number' of marginal adjusted polarized relays each being connected between any of the branches of said line and earth over two series-connected eondensers, means to actuate the polarized relays selectively by current impulses of diil'erent magnitudes and directions, means to shunt one of the said two condenser-s when the polarized relay is at rest, and means to connect the other condenser in parallel with an auxiliary relay when the polarized relay is energized.

l. In a selective system a line, a number l of marginal adjusted polarized relays each being connected between any of the branches of said line and earth over two series-connected condensers` means to actuate the polarized relays selectively by current impulses of different magnitudes and directions, means to shunt one of the said two condensers when the polarized relay is at rest, and means to connect the other condenser in parallel with an auxiliary relay when the polarized relay is energized` the said auxiliary relay being provided with a contact over which the one coating of a third condenser is connected to a current source of a certain potential, the other coating of the condenser being connected to earth.

5. In a selective system a line, a number of marginal adjusted polarized relays each being` connected between any of the branches of said line and earth over two series-connected condensers, means to actuate the polarized relays selectively by current impulses of different magnitudes and directions, means to shunt one of the said two condensers when the polarized relay is at rest, means to connect certain potential by the auxiliary relay and then to a polarized relay.

6. In a selective system a line, a number of marginal adjusted polarized relays each being connected between any of the branches of said line and earth over two series-connected condensers, means to actuate the polarized relays selec-tively by current impulses of different magnitudes and directions, means to shunt one of the said two condensers when the polarized relay is at rest, means to connect the other condenser in parallel with an auxiliary relay when the polarized relay is energized, a third condenser the one coating of which is connected to earth while the other may be first connected to a current source of'certain potential by the auxiliary relay and then to a polarized alarm bell.

7. In a selective system a line, a number of marginal adjusted polarized relays each being connected between any of the branches of said line and earth over two series-connected condensers, means to actuate the polarized relays selectively by current impulses of different magnitudes and directions, means to shunt one of the said two condensers when the polarized relay is at rest, means to connect the other condenser in parallel with an auxiliary relay when the polarized relay is energized, a third condenser the one coating of which is connected to earth while the other may be first connected to a current source of certain potential by the auxiliary relay and then to a polarized alarm bell which is positively controlled or biased by means of a spring.

In testimony whereof I aliix my signature.

.DOUGLAS CORMACK CROWE.