US2490054A - Party line telephone system - Google Patents

Description

lDec. 6, 1949 w, HATTON PARTY LINE TELEPHONE SYSTEM Filed March 22, 1945 HGENT- Patented Dec. 6, 1949 l ;;;1

PARTY LINE TELEPHONE SYSTEM William Hatton, Maplewood, N. J., assignor to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application March 22, 1945, Serial No. 584,060 1o claims. (ci. 179-17) This invention relates to automatic telephone I systems, and has for an object to provide a simple and economical arrangement for selectively ringing a called party on a multi-party line.

Another object of the invention is to provide an improved arrangement for controlling ringing voltages of different station-selecting characteristics and for impressing the selected ringing voltage over the called multi-party line.

A further object of the invention is to convert by an improved adapter circuit the penultimate and nal selectors of an automatic telephonev switching system from an individual to a multiparty line basis.

A still further object of the invention is to arrange the nal selectors for party line working on a terminal per station basis in a manner such that signaling for individual lines remains substantially the same.

In accordance with this invention, party lines are accommodated in the banks of the final selectors on a terminal set per station basis by associating with the terminal sets and with the party line a relay adapterV circuit, which is provided with a particular identifying voltage for each of the stations and which in response to a call is adapted for initiating the selection in one of the selectors of the characteristic ringing voltage that is to be impressed over the line.

A feature of the invention resides'in a nal selector switch in which the (a) and (b) or talking terminals of the terminal sets allocated to a party line are connected to a two-relay adapter circuit which determines the selection of the proper ringing frequency.

A still further feature ofthe invention resides in a selector switch in which a particular one of a plurality of different ringing voltages of station-selecting characteristics is arranged to be impressed over a subscribers line in response to a particular voltage indication from the terminal set engaged by the final selector.

Other features of the invention relate to circ uit improvements which Will be apparent from the following detailed description of the drawing, which shows by means of the usual circuit diagrams a sufficient amount of apparatus to enable the invention to be described and understood.

The invention is illustrated in an automatic telephone system of the harmonic ringing type employing rotary-type line finder and selector switches including associated sequence switches; but it is to be understood that the invention is not to be limited in its application to the specific arrangement shown.

Referring to the drawing, there is shown a multi-party line having four subscriber stations A, B, C and D associated therewith, a two-relay adapter circuit associated with four terminal sets i in the bank of a final selector switch, and a penultimate selector switch including the pertinent sequence switch cams, harmonic ringing supply having the usual distinguishable frequencies, and relays for controlling the frequency selection of said ringing supply.

The subscribers stations are of the type normally employed in automatic telephone systems and each includes a dial for use in obtaining connections with any other station. Four stations are shown connected over one line to the exchange, the line circuitat the exchange comprising the usual cut-olf relay and line relay, the latter of which is actuated when any of the above subscribers initiates a call. As usual, the line is also multiplied in the banks of a group of line finders. As mentioned hereinbefore, the line finder and selector switches are of the wellknown rotary type and a description of the details thereof is not required for an understanding of the present invention. A system of this type is fully described and illustrated in Electrical Communication, Volume 3, published in the U. S. by Gerald Deakin, January 1925, pages 153 to 189. The terminals of the final selector are arranged on a terminal-per-station basis, that is, a separate set of terminals is provided in the selector switch for each party line subscribers station.

In order to instal a party line, the terminal sets in the banks of the final selectors allocated to the party line stations are connected to a party line` assembly frame to which is also connected the party line itself and a two-relay adapter circuit, comprising marking relay l and line-connecting relay l2, as shown. It Will be noted that the contacts a and b of the terminal set of party A are connected directly to the party line, but the a contacts of parties B, C, and D are connected over respective back contacts of relay III to line conductor I3 and the b contacts of parties B, C, and D are connected in multiple over a front contact of relay l2 to complete the connection to line conductor Il. The test contact terminals c for al1 four parties are multipled together for obvious reasons. While the invention has been disclosed with reference to a four-party line, it is apparent that the invention may be readily applied to party lines having a greater or lesser number of stations by anyone skilled in the telephone switching art.

tion A, the call having been routed to the Final l selector in known manner, which has found the called party line to be free, and assume-further`r that the sequence switch has reached position Ij. Under this assumption it will be recognized that positive battery to relay I4 in the Penultimate selector to energize same; and at the lowermost front contact connects ground to relay I2 in a circuit that can be traced from grounded positive battery through winding and bottom back contact thereof, bottom front contact of relay Ill, and thence through winding of relay I0 to ground. Relay I2, however, does not operate at this time in view of the resistance 2| of the Penultimate selector being in parallel with the Winding thereof which is of relatively high resistance.

The circuit for the operation of relay It may s be traced from grounded positive battery through the bottom set of terminals, that is, for party A, has been seized by the Final selector, terminals a, b thereof being connected directly to the lineconductors I3, II, respectively. It will be further recognized that operationof the sequence switch camy K'of the Penultirnate. selector has no eife'ct with respect to thev selection of ringing current up to position I2, inclusive, inasmuch, asthe terminals a, b are4 not routedv through relays.

Il), I 2.. However, when sequence switch cam K reaches its. 13th position, ringing current is irnpressed over theline conductors II, I3 to signal` the call'edsubscriber A. This. circuit can be traced from grounded 16% cycle ringing supply through the right back contact of relay I5, left back contact of relay I4;V winding of relay I8, lower and,v upper left springs of sequence switch cani K', brushes and terminals of Penultimate and.l

Final selectors, respectively,.and thence over conductor b andlinec'onductor IfI to the subscribers.

set A where it is returned over line conductor I3 and conductor a, through terminals and brushes:

of Final and Penultimateselectors, respectively,

left springs of sequence switch cam O, and thence.

to ground over the make contact of relay I9,

which had been operated previously through a.

circuit not required to be described` herein. Ringing continues. over the line until the subscriber answers4 or until the sequence switch cam K reaches position I5..

Upon subscriber Av answering, talking battery (not shown) is connected. to the called line and the sequence switch: of ther Penultimate selector passes in the usual manner to. position I and remains there during; thezconversational period. After the calling subscriber hangs up, the sequence switch passes to position I5 and` thence to position IL'I upon the calledgsubscriber hanging up. The sequence switch. then continues to position I afterwhich it returns-.to its normal position in readiness for an'othercall. It is readily apparent frornthe above that the addition of the relay adapter circuit toftheFinal selector has no materialV effect uponthe manner in which party A is selectively rung.

Assuming now that any of the other three parties is to be called, for example, partyD, and the appropriate setl of terminals` has been seized by the Final selector, then in. this instance upon the sequence switchof thePenultimate selectorV reaching position IUI/2, marking relay I5 is energized in a circuit that.. can be traced. from grounded battery through.` the two upper springs of sequence switch cam.P,.resistance 2|, brushes and terminals ofPenultimate and Final selectors, respectively, over lead b, via upper back Vcontact of line-connecting relay I2, andthence to ground through the winding offrelay' I0. In energizing, relay Il! at its uppermost front contact connects left winding thereof, lower right and upper left springs of sequence switch cam S, brushes and terminals of' Penultimate and Final selectors, reg.spect ively, over lead a, through uppermost make contact of relay I0 and resistance 22 to battery and-ground. Relay I4, in operating,` locks itself in a circuit that can be traced from grounded positive batterythrough right frontA Contact thereof and to ground: over.l right springs. of sequence switch cam J ofthe Penultimate selector. Relay I6 also, in operating, closes its. left front contact and. connects it' through the leftback Contact of relay I5 to a. harmonic ringing supply source of 50 cycles. No material change in. circuit operation' occurs during thev passage of. the sequence switch from'. positions |01@ to I2. However, uponposition I2 being reached the upper and lower left springs of sequence switch. cam S close and provide an energizing circuit for relay I5, which can be traced froml. ground through the right winding thereof, left springs of sequence switch k cam S, brushes and terminals of Penultimate and Final selectors; respectivelyv over lead a through uppermost front contact of' relay IQ, and thence through` resistance 22v tol positive battery and ground. Relay I5, in operating, at its right front contact connects-331/3- cycle harmonic ringing current thereto but this is ineffective inV view of the operation. of relay I4.; at its outer-most left front contact provides a locking circuit', which canv be traced from positive grounded battery through 'the left winding thereof to ground through the righ-t springs ofsequence switchr cam J; at -it's inner left front contact connects harmonic 'ringing current of 662/3v cycles thereto, which is ineffective until sequence switch cam K reaches position I3- It is thusf seen that the marking potentialA of positive battery provided by markingrelay` IU, which potential is characteristic' of party DLis effective by operation of relays- It: and I5 to'causeselection of a harmonic ringing frequency ofv 66% cycles per second.

vIt is-to be noted 'that when the sequence switch leaves position I2 thatthe above-traced energizing-battery via 'sequence switch cam P for relay Ill2 is disconnected. However, inasmuch as energizing battery,throug h the winding of relay i2, is also connected' to the windingV of relay IU, this relay remains energizedl momentarily and relay I2 operates, in the hereinbefore-traced circuit. Relay I2, in operating, opens. the energizing circuit for. relay Ill: 'at 'its lower back contact and.

5` ringing circuit-can be traced from grounded ringing supply of 66% cycles over the left inner front contact f relay I5, left front contact of relay I4, winding of relay I8, springs of sequence switch cam K, over conductor b through the Penultirnate and Final selector switches, upper front contact of relay I2, over line conductor Il to subscribers station'v D, back over the subscribers loop including line`conductor I3, uppermostI back contact of relay -IIl, back over conductor a and through Final and Penultimate selector switches, left springs of sequence switch cam O, and front contact of relay I9 to ground. The remainder of the call proceeds in a manner similar to that described for party A, except that line-connecting relay I2 also releases upon the parties hanging up.

A similar procedure obtains in selecting the characteristic ringing voltage for party C. In this instance, when the selector terminals of party C have been seized and marking relay I operated, the upper intermediate front contact has ground placed on the a wire, which, obviously, cannot operate grounded winding of relay I5. However, this ground does operate the left winding of relay I4, which energizes in a manner above-described and which furnishes the called line with 50 cycle harmonic ringing current.

Similarly, if party B is to be called, and assuming the terminals thereof have been seized by the Final selector and relay I0 to have been operated in the above-described manner, then negative battery through resistance 24 is connected via the lower intermediate front contact of relay I0 in succession to relays I4 and I5 of the Penultimate selector. Obviously, relay I4 cannot operate but relay I5 does, in an obvious circuit that does not require tracing, with the result that harmonic ringing voltage of 331/3 cycles is impressed upon the subscribers line circuit.

It will be appreciated that the terminal sets allocated to a party line need not be adjacent to one another in the terminal banks of nal selectors.

While this invention has been shown and described as embodying certain features merely for the purpose of illustration, it is clear to anyone skilled in the machine-switching art that many modifications are possible without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a telephone exchange system, a party line having a plurality of stations associated therewith, a final selector having an individual set of terminals for each one of said stations, a plurality of sources of ringing current of different characteristics, sources for a plurality of marking signals, a relay associated with said party line, means for energizing said relay upon the seizure of said line by said nal selector over one of said sets of terminals, means controlled by said relay for connecting one of said marking signals to a terminal of said one set of terminals, and means responsive to the marking signal thus connected for selecting a particular one of said sources of ringing current for application to the party line.

2. The system according to claim 1, and a second relay common to said party line and controlling the circuit of the rst relay.

3. The system according to claim 2, an energizing circuit for the second relay including a contact of the first relay, and a holding circuit for the second relay including a terminal in any one of the sets belonging to the party line.

4. The system according to claim 1, and in which one niarking signal is positive and another marking signal negative potential, and the means responsive to the marking signal comprising twol relays one responsive only to positive and the other only to negative potentials.

5. The system according to claim 4, and in which the sets of terminals include talking terminals to which said marking signals are connected, and said two relays are connected in multiple over a inal selector with a talking terminal of eachcalled party line station.

6. In a telephone exchange system, a party line having four stations associated therewith, a iinal selector including four individual sets of terminals for said line, four sources of ringing current of different characteristics, sources for two marking signals, a relay associated with said party line, means for energizing said relay upon the seizure of said line by said nal selector over any one of three sets of terminals, a front contact for said relay to connect one marking signal to one of the three sets and a second front contact for said relay for connecting another marking signal to another one of said three sets, and means variably operable depending on the presence or absence of the marking signals for selecting a particular one of said sources of ringing current for application to the party line.

'7. In a telephone exchange system, a party line having a plurality of stations associated therewith, a final selector having an individual set of talking and test terminals for each one of said stations, means including said final selector for extending a calling line to any one of said sets of terminals, a plurality of sources of ringing current of different characteristics, rst and second relays associated with said party line, back contacts for the second relay for connecting a talking terminal of all but one of said sets of terminals to the energizing winding of the first relay, front contacts for the second relay for connecting the last-mentioned talking terminals to one of the conductors of said party line, sources of a plurality of marking signals, front contacts for the rst relay for connecting one of said marking signals to one and the second marking signal to a second talking terminal of said all but one of said sets of terminals, and means responsive to said marking signals for selecting a particular one of said sources of ringing current for application to the called party line.

8. The system according to claim 7, and an energizing circuit for the second relay controlled by front contacts of the iirst relay.

9. In a telephone exchange system, a plurality of party lines each having four stations associated therewith, a final selector having individual sets of talking and test terminals for each party line station, means including said nal selector for extending a calling line to any one of the sets of terminals of the called party line, four sources of ringing current of different characteristics, a rst and a second relay associated with each party line, back contacts for the second relay for connecting a talking terminal of three of said sets of terminals to the energizing winding of the first relay of the called party line, front contacts for the second relay for connecting the talking terminals of the three sets to one of the conductors of the called party line, sources of a plurality of marking signals common to the party lines, front contacts controlled by the second relay for connecting one of said marking signals to one and the second marking signal to a second talking terminal of said three sets of selecting .a particular xmeofaidsOurces'of -ring- The following references vare of record `in 'the ing current for amilicaition @to he v.called party le of this patent: line. 5 Y

F10. The system accordingto claim 19. an ener- UNITED STATES PATENTS gizing circuit for the second :relay controlled in Number Name Date a iront contact ofthe @sscciatedirst relay, and 1,565,727 Eiendly Dec. 15, 1925 a holding `circuit for :the s econd relay including 1,849,088 Hovland Mar. 15, 1932 the test terminal of anyrof'the four sets. 1o 1f970,337 Pope Aug. 14,1934v

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