US2247507A - Telephone system - Google Patents

Description

y 1941- E. H. LAN HAM ETAL 2, 7,507

I TELEPHONE SYSTEM. A

Filed June 10, 1939 2 Shets-Sheet 1 M M M, W ...F

without mm m u 5. H. LAN/1AM INVENTORS L. R. 'WALLER ATTORNEY y 9 E. H. LANHAM ETAL 7,507

TELEPHONE SYSTEM Filed June 10, 1939 2 Sheets-Sheet 2 E. H. LANHAM L. R. WALLER IN VEN TORS mfTORA Ey Patented July 1, 1941 TELEPHONE SYSTEM Edward H. Lanham, Nctre Dame de Grace, Quer, Montreal, Quebec, Canbec, and Lee R. Walle ada, assignors to Western Electric Company,

Incorporated, New York, N. Y., a corporation of New York Application June 19, 1939, Serial No. 278,404

14 Claims.

'This invention relates to telephone systems and particularly to intercommunicating or conference systems involving the use of loud-speaking and receiving equipment.

It is the object of this invention to provide an improved system of telephone intercommunication involving a plurality of stations which normally have access to and are accessible from a central ofiice, such as a private automatic exchange.

In accordance with a feature of the invention,

a system is provided in which the regular private automatic exchange facilities are employed for the additional service of loud-speaker intercommunication.

In accordance with another feature of the m vention, an executive at a primary station may establish connection and hold conversation with any or all of a plurality of secondary or subordinate stations simultaneously by dialing the code numbers of the desired secondary stations and may, at any time during an established conversation with one or more secondary stations, call in any other secondary stations without interference with the connections al-v ready established and without necessitating any operation by the subscribers whose stations are already connected to the conference line.

A further feature of the invention resides in the use of means for discriminating between the use of an executive service set and a regular telephone set at the "primary station whereby a call originated at the primary station is automatically extended either to another station of the intercommunicating or conference system or to a central ofiice, depending upon which equipment is employed.

These and other features of the invention will be best understood from a following detailed description made with reference to the accompanying drawings in which:

Fig. 1 illustrates a primary station A and a plurality of secondary stations B and C each equipped with loud-speaking apparatus used in connections established over the conference or intercommunicating line L, and with facilities for establishing connections to a private automatic exchange by way of the automatic switches illustrated schematically at the right of the figure; and

Fig. 2 illustrates an automatic switch W which is controlled from the primary station A in effecting the selective connection of any or all of the secondary stations to the line L and also discloses the relay equipment which funcsignals are transmitted to tions to step the switch W and to transmit call and busy signals; In reading the drawings, Fig. 2 is placed immediately below Fig. 1.

Before entering into a detailed description of the operation of the system disclosed in the drawings, a brief reference will be made to the equipment located at each station; to the normal conditions of the several lines with respect to the intercommunicating or conference line and private automatic exchange apparatus; and to the other equipment employed in completing conference connections and for signaling purposes.

The primary station A is equipped with a distant talking transmitter 6!, a loud-speaker M, an amplifier 62, an executive service key Ill and an auxiliary dial I2. This equipment supplements the regular station equipment, dia-' grammatically indicated at 63, and the dial l9. The primary line is normally associated with the conference line L and may be transferred therefrom to the private automatic exchange equipment by the operation of relay IS. The equipment at the secondary stations B and C is similar to that at the primary station except at no auxiliary dial, such as dial I2, is required. Each secondary line, or section individual thereto, terminates in contacts of the line finders Sb and Se whose contacts are multipled with the contacts of connector switche Cb and Cc, which switches serve in completing calls incoming to the various stations from the private automatic exchange. The transfer of the secondary lines from their private automatic exchange switch terminals to the intercommunleating line L is effected by the combined operations of two relays, such as relays 46 and 50. The stepping switch W which is controlled from the primary station may be of any well known type and functions to selectively signal the various secondary stations and prepare them for connection to the line L. The actual connection of the secondary stations to the line L is accomplished when the subscribers thereat respond to an incoming call signal. The amplifiers which constitute part of the substation equipments may be of any well-known type and are balanced to permit two-way loud-speaker conversation to be carried on freely without the necessity of operating a press-to-talk key. Call and busy the stations under the control of vibrating reed type relays, such as 35 and 42, which function for a predetermined interval of time to apply a signal of correspondins duration to the called stations.

16, being marginal, does not operate in upper V armature causes battery, upper winding of relay l3, conductor I4 of line L, back contact and inner lower armature of relay I5, winding of marginal relay [6, lower armatures and back contacts of relays l1 and i8, retard coil H, closed contacts of switch Ill, pulsing contacts of dial l2, back contacts and upper armatures of relays l8 and H, pulsing contacts of th primary subscribers regular dial l9, upper armature and back contact of relay l5, conductor 2 30f line L, to ground Relay series with the high-resistance retard coil H. 'Relay l3, however, does operate and in attracting its relay 21 (Fig. 2) to operate in a circuit extending from grounded battery, winding of relay 2|, conductor '22, left armature and back contact of relay IE, conductor2-3, to ground by way of the front contact and. upper armature of relay l3. At its lower armature relay l3 disconnects ground from conductor 30.

by way of the lower winding of relay l3.

At its inner right armature, relay 2| con-' nects ground to conductor 24 which extends to [the sleeve terminals of the switches C and S, thus marking the primary station A busy to calls theretooriginating at or extended from the central office or privat automatic exchange A at which the switches are located. At its inner right armature and back contact relay 2| opens the circuit to the lower winding of relay l5. In attracting its outer right armature, relay 21 connects conductor 25 to conductor 26, thereby short-circuiting the winding of marginal relay "l6 so that relay I3 is now held operated in a circuit which does not include the winding of relay IE but includes the outer right armature and front contact of'relay 2|. The functions performed by the left armatures of relay 2! will appear presently.

After actuating key ll] as just described, the

subscriber at pr'imary station A manipulates "the dial 12 in accordance with the code assigned to the secondary station B. Assuming this code to be "3, the subscriber dials the digit 3 in the well-known manner. Relay l3, whose operating circuit includes the pulsing contacts of dial l2, followsthe dial pulses. As soon as the 'dia1-|'2 is movedoif normal, the off-normal spring contacts 21A shunt the retard coil ll', removing its impedance from the pulsing loop. Relay i3 does notfcll'ow "the dial pulses even though H the retard coil is effectively shunted because the winding' of relay I3 is short-circuited by the outer right armature and front contact of relay 21, as hereinbefore described.

' On the first rele'se of relay l3 in response to ates "in a circuit extending'from grounded batthe actuation of dial l2, relay 28 (Fig. 2) operductor 33, lower farmature and back contact of relay 13 to ground; Relay "28 is a slow-to-release device and remains operated during the pulsing period.

Stepping magnet 3| operates in parallel with relay 28 and follows the repeated releases and operations of relay l3 caused by the manipulation of dial l2. Magnet 3| accordingly functions in a well-known manner, to step the brushes of switch W until they engage the third contact of each level. These contacts are designated on the drawings by the letters b and b, respectively.

When relay 28 operated on the first-release of relay l3, it caused relays 32 and 33 to operate in obvious circuits which include the inner right armatur and front contact of relay 28. Relay 33, in operating, locks in a circuit extending from grounded battery, its own winding and inner left armature and associated make-beforebreak contact, conductor 34 to ground at the front contact and outer right armature of slowto-release relay 32. The functions performed by the other armatures of relays 32 and 33 will appear as the description progresses.

When the dial !2 returns to normal after the dialing of digit 3, relay 28 releases due to the fact that the circuit to its winding remains open at the lower armature and back contact of relay l3. Relay 23 in restoring its armatures opens the circuit to th winding of relay 32. This relay, being slow to release, does not immediately restore its armatures. Before it does So a circuit for relay 35 is completed which extends from grounded battery, winding of relay 35, front con-- tact and left armature of relay 32, conductor 36, left armature and back contact of relay 28, brush and contact I) of switch W, conductors 31 and 38 to the sleeve terminals of the automatic switches Cb and Sb at the private automatic exchange. If the line of secondary station B is busy due to an in or out call being established over the regular private automatic exchange equipment, ground potential, in accordance with well-known practice, will be found on the sleeve lead. Relay 35 would thereupon operate in the circuit just traced, before relay 32 releases its armatures.

Relay 35, which is of the vibrating reed type, closes an obvious circuit for slow-to-release relay 39. Due to its vibrating characteristic, the armature of relay 35 maintains relay 39 operated for several seconds after the release of relay 32. In attracting its left armature,'re1ay 39 establishes an obvious circuit for relay 4!). Relay Ml operates and at its right armatures and front contacts connects a busy ton signal source to the line L. This signal is reproduced in the loud-speaker ll at station A to advise the calling subscriber thereat that the called station E is busy. The busy tone current transmitted over line L does not operate relay 18 at the primary station A.

If the called station B is not busied by the private automatic exchange equipment, there will be no ground potential on'the sleeve lead .38 and consequently relay 35 will not operate when relay 28 releases upon the completion of dialing.

Assuming the called station B to be idle, relay 28 releases upon completion of dialing, in turn releasing relay 32. Relay 32 opens the locking circuit to relay 33, which relay, however, being slow to release does not restore its armatures immediately so that a circuit is now established which extends from grounded battery, winding of slow-to-release relay 42, left armature and back contact of relay 40, front contact and right armature of relay 33, to ground by way of the back contact and outer right armature of relay 32. Relay 42 operates in this circuit before relay 33 releases and in turn causes relay 43 to operate in an obvious circuit. Relay 42, like relay 35, is of the vibrating reed type and due to the vibrating characteristic of its armature maintains relay 43 operated for several seconds after the release of relay 33.

At its left armature and front contact relay 43 extends ground potential over conductor 44, brush and third terminal I) of switch W, conductor 45, winding of relays 46 and 41 in parallel to grounded battery. Relay 41 operates and connects tone current to the called station B which operates the loud-speaker 48 to produce a call signal. Relay does not operate on this tone current. When relay 42 ceases to vibrate and slow-to-release relay 43 has subsequently released its armatures, relay 41 connects the tone source from the called station E and the line conductors from station E are extended to the outer armatures of relay 46.

Relay 46, which operated in parallel with relay 41, locks to ground at the outer left armature and front contact of relay 2| by way of conductor 49 and the inner upper armature and makebefore-break contacts of relay 46. At its inner lower armature relay 46 connects ground to the sleeve terminals of switches Sb and Cb to make the called line test busy to the regular private automatic exchange equipment. At its outer, upper and lower armatures, relay 46 transfers the tip and ring conductors of the called line from the private automatic exchange pares an operating circuit for relay 5|].

In response to the tone signal, the subscriber at station B operates station key 5|, thereby completing the circuit for relay 50. This circuit extends from grounded battery, upper winding of relay 50, front contact and outer upper armature of relay 46, back contact and upper armature of relay 41, closed contacts of dial 1|, upper armatures and back contacts of relays 12 and I6,

closed contacts of key 5|, coil 52, lower armatures I and back contacts of relays 1D and 12, lower armature and back contact of relay 41, outer lower armature and front contact of relay 46, lower winding of relay 50 to ground. The impedance of coil 52 is such as not to interfere with the transmission of speech.

Relay 50 in operating disconnects the station equivalent network 53 from the intercommunicating line L and connects the called station line thereto. ondary station B are thus connected together and two-way conversation over the line L may proceed on a loud-speaker basis.

When relay 42 ceases to vibrate and releases relay 43, the rotary switch release circuit is closed from ground at the outer right armature and back contact of relay 26, right armature and back contactof relay 43, right armature and back contact of relay 39, outer left armature and back contact of relay 33, inner right armature and back contact of relay 32, oiT-normal springs 54 of switch W, winding of release magnet 55 to battery and ground. Release magnet 55 functions in a well-known manner to return the switch to normal.

At the termination of subscribers at stations the primary service key and 2| conversation between the A and B, the subscriber at station restores the executive II] to normal whereupon relays l3 release, allowing relay 46 to restore its releases and dis- 2 equipment and pre- The primary station A and the secarmatures and the circuit is restored to normal.

It will be noted thatimmediately after the called station B was signaled, the switch W was restored to normal so that it is in readiness to receive further pulses from dial I2 at station A should the subscriber thereat desire to include other of the "secondary stations in a conference circuit. If during the conversation between the subscribers at stations A and B the subscriber at station A wishes to call in one or more additional secondary stations for conference purposes, it is only necessary that the dial I2 be actuated to dial the call number or numbers of the station or stations desired. Such operations do not, in any way, interfere with the connection already established.

Relay |3 will respond to the dial pulses in the same manner as when the "secondary station was dialed and the consequent relay operation will be the same as already described. The switch W will, of course, be positioned on different bank contacts in accordance with the codes dialed and will operate relays 46 and 41 corresponding to the stations called. In each case, switch W returns to normal after performing its functions either of reporting the called line busy or operating the associated relays 46 and 41 to prepare the called line for connection to the common talking circuit L and to apply a tone signal to the called line.

When the subscriber at primary station A desires an outside connection, the receiver of the regular telephone set is removed from its switchhook. Relay I1 thereupon operates in a circuit extending from grounded battery, upper winding of relay I3, conductor I4, back contact and inner lower armature of relay I 5, winding of marginal relay I6, over the closed subset loop, winding of relay I1, upper armature and back contact of relay I5, conductor 20 to ground by way of the lower winding of relay I3. Relay I1 operates in this circuit and disconnects the executive loudspeaking equipment from the line. Relay l6 also operates under this condition due to the absence of the high resistance retard coil II from the circuit and in turn operates relay |5 over an obvious circuit. I

Relay I5 operated transfers the primary station A from. the line L to the regular private automatic exchange line. At its two lower armatures and front contacts relay 5 shunts down relay I6. Relay |.5, however, is held operated in a circuit extending from grounded battery, lower winding of relay I 5, conductor 56, back contact and inner right armature of relay 2|, conductor 24 to ground on the sleeve terminal of switch S- at the exchange. It will be understood that when relay I5 operated, line finder S functioned in the well-known manner to seize the calling line and apply ground potential to the sleeve terminal thereof.

On an incoming call to the primary station from the private auto-matic exchange, relay |5 operates from ground on the sleeve circuit of the private automatic exchange equipment and cuts the private automatic exchange line through to the primary" station and shunts relay I6. Ringing current transmitted from the private automatic exchange operates relay I8 which functions to cut off the amplifier equipment at the primary station during ringing periods. Relay I1 operates when the called subscriber answers the call by removing the receiver from its switch-hook and maintains the executive service equipment disconnected from the line.

The subscribers at the secondary stations B and- C may initiate calls to and receive calls 'from the private automatic exchange in the well-known manner, by employing the regular telephone set. Relay 72 operates when the receiverat the secondary station is removed from its switchhook and cuts off the loud-speaking equipment from the line. Manipulation of the dial H causes the switches at the private automatic exchange to function in the well-known manner to extend the connection to a called station.

What isclaimed is: 1. In a combined automatic telephone exchange and loud-speaking intercommunicating system, a primary station having a loud-speaking telephone set including a call initiating key and a regular telephone set, an intercommunicating line, a link circuit extending to automatic switches at a central office, and means for discriminatingbetween the use of said call initiating key and said regular telephone set at said 7 primary station in originating a call, whereby central ofiice linkcircuit, said primary station 'beingnormally associated with said intercommunicating line circuit and disconnected from saidoentral ofiice link circuit, switching means responsive to the use of said regular telephone set in originating a call for transferring said primary station from said intercommunicating line and connecting it to said central ofiice link circuit, and means included in said loud-speaking telephone set for rendering said switching means inoperative when said loud-speaking telephone set is employed in originating a call at said station.

V 3., In a combined private automatic telephone exchange and loud-speaking interccmmunicating system, a primary station, ,a loud-speaking telephone set and a regular telephone .set at said station, an intercommunicating line circuit, a

-central oflice link circuit, said station being. nor- 'mally associated with said intercommunicating line circuit and disconnected from said central office link circuit, a marginal relay included in circuit vbetween said primary station and said intercommunicating line circuit, switching means controlled thereby, means effective upon the use of said regular telephone set in originating a call for causing the operation of said marginal relay whereupon said switching means operates to disconnect said station from said intercommunicating line and connect it to said central ofiice link circuit, and means includinga key associated with said loud-speaking telephone set for ren- 'dering said marginal relay unresponsive to the use of: said loud-speaking telephone set in originating a call at said station.

4. In a combined automatic telephone exchange and loud-speaking intercommunicating system, an intercommunicating line circuit, a station thereon having a loud-speaking telephone set including a key and a dial a central ofiice,

*to the operation of the key at "an automatic switch thereat having a terminal corresponding to said station, means responsive said station for applying a busy potential to said terminal, a second station, means including the dial at said first station for automatically signaling said second station, and means operating when the subscriber at said second station responds to the signal for connecting said second station to said intercommunicating line. 7

5. In a combined automatic telephone exchange and loud-speaking intercommunicating system, an intercommunicating line circuit, a station thereon having a loud-speaking telephone set including a key and a dial, a second station normally disconnected from said intercommunicating line circuit, a central ofiice, automatic switches thereat having terminals corresponding to said stations, means responsive to the operation of the key at said first sta'tionfor applying a busy potential to the central office switch terminal corresponding to said first station, means including the dial at said 'firststation for automatically signaling said second station and applying a busy potential tothe central office switch terminal corresponding to said second station, and means operating when the subscriber at said second station responds to the signal for connecting said second station to said intercommunicating line,

6. In a combined automatic telephone exchange and loud-speaking intercommunicating system, an intercommunicating line circuit, a station thereon having a loud-speaking telephone set including a key and a dial, a second station normally disconnected from said intercommunieating line circuit, a central ofiice, automatic switches thereat having terminals corresponding to said stations, means responsive to the operation of the key at said'first station for applying a busy potential to'the central ofiice switch terminal corresponding to said first station, means responsive to the actuation of the dial at said first station subsequent to the actuation of said key for testing the central office switch terminal corresponding: to said second station, and means responsive to busy potential encountered on the central office switch'terminal corresponding to said second station for applying a tone signal to said intercommunicating line, circuit. for reception by the loud-speaker at said first station.

7. In a combined automatic telephone exchange and loud-speaking intercommunicating system, an intercommunicating line circuit, a

station thereon having a loud-speaking telephone "set including a key and a dial, a second station normally disconnected from said intercommunieating line circuit, a central oiiice, automatic switches thereat having terminals corresponding to said stations, means responsive to the operation of the key at said first station for applying a busy potential to the central ofiice switch ter minal corresponding to said first station, means responsive to the actuation of the dial at said first station subsequent to the actuation of said key for testing the central office switch terminal corresponding to said second station, and means operating a predetermined interval of time after the central oiiice switch terminal corresponding to said second station is tested and found idle for transmitting a tone signal to said second station.

8. In a combined automatic telephone exchange and loud-speaking intercommunicating system, anintercommunicating line circuit, a station thereon having a loud-speaking telephone set including a key and a diaLa second station normally disconnected from said intercommunieating line circuit and having a loud-speaking telephone set including a key, a central office, automatic switches thereat having terminals corsecond station for reception by the loud-speaker thereat.

9. In a combined automatic telephone exchange and loud-speaking intercommunicating station responds to the signal for connecting said second station to said intercommunicating line.

10. In a combined automatic telephone exchange loud-speaking intercommunicating system, an intercommunicating line circuit, a stanection for disconnecting said loud-speaking telephone set from 12. In a combined automatic telephone exchange and loud-speaking intercommunication pleting the connection of the called line to the intercommunicating line.

. In a telephone conference system, a called 13 station, a calling station, a line circuit normally said automatic switch. 14. In a telephone conference system, a calling station, a plurality of called stations, a line cirthereof to said line independent of said automatic switch, and means operating at the expiration of the predetermined interval of time during which tli called station is being signaled for releasihg said automatic switch-whereupon sa-i-d automatic switch becomes available for further control by connecfiion to said li'ne' without distufloing the connection of said-one o said line.

f said called stations with LEE R. WALLER.

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