US1142678A - Telephone-exchange system. - Google Patents

Description

G. DEAKIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAR.8|1912.

1,142,678. Patented June 8, 1915.

WITATESSES.

UNITE 63323.15 OF BERKELEY, CALIFORNIA.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters IPatent.

Patented June 8, 1915.

Application-filed March a, 1912. Serial n. 682,390.

To all whom it may concern: 7

Be it known that I, GERALD Dmnm, a citizen of the United States, residing at Berkeley, in the county of Alameda and State of California, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a specification.

My invention pertains to an improved automatic repeater circuit adapted to receive electric impulses from a telephone station equipped with an automatic calling device, and to transmit in modified form, the electric impulses so received and in such a manner as to operate switches in an automatic telephone central oflice, which may be of the type which cannot be operated in direct connection with the subscribers station calling device.

At the present time, there are in Wide commercial use, two types of automatic telephone exchange systems, mechanically similar but electrically dissimilar. In the first and older type, the impulses originated at the calling telephone station for the operation of the switches at the central oflice, are sent alternately over the two line Wires, the earth forming the return path in each case. After the called line'has been selected in the central oliice, by the proper switch, the call bell at the called station is caused to ring by depressing a ringing key at the calling station, Which grounds one side of the calling line. The release of a completed connection thus established, is effected by simultaneously grounding both sides of the calling line. In the second and later system, the connection is established by rapidly male in In this system the earth is not used in establishing a connection. The release of a completed connection thus established, is efiected by permanently opening the calling line circuit. The calling device required for use in connection with the later system is a very simple piece of mechanism, consisting merely of two contact springs, adapted to alternately break and make contact when the device is operated. In the older system, the calling device is much more complicated, in that it has to apply a series of grounds to one side of the line and then a ground to the other each time it is operated. Furthermore, the hookswitch has to be connected with the calling device mechanism or otherwise adapted to momentarily ground both and breaking the calling line circuit.

sides of the line, when the'receiver is replaced upon it.

The object of my improved repeater cir-. cult is to permit the use of the simple make and break calling device at the subscribers station, in connection with the older type of central oflice equipment, requiring the use of an earth return circuit for its operation. Typical selector and connector switches of the ,old type, are described in United and break calling device at the subscriber's station and automatic switches at the central oflice, requiring the use of both sides of a pair ,of line wires with an earth return for the establishment of a connection, and the simultaneous grounding 01 both sides of the line for releasing the connection.

In the repeater circuits now in common use the talking circuit is normally closed through the repeater. Should this talking circuit contain condensers or other form of electrical capacity, the electric impulses received and transmitted will be interfered with by the charging and discharging of the condensers. To overcome this point the talking circuit in my improved-repeater is adapted to remain open until the ringing key at the'calling station is depressed. The accompanying drawing illustrates my improved repeater circuit associated with a subscribers station telephone circuit, at A, equipped with a simple make and break calling device. At B are shown the controlling line relays of an automatic central oflice switch of the ground return type.

At A is shown a simple form of subscribers station telephone circuit, consisting of a transmitter, receiver, switchhook, ringing key R, and at 3, contact springs of the calling device, adapted to rapidly open and close the line circuit, when the device is op.- erated.

L and L represent two line wires connecting station A with the repeater.

C and D represent relays of the type ordinarily used in telephone circuits. E, F, .G

and H represent similar relays, the magnetic cores of which are provided with copper sleeves or shortcircuited windings, or otherwise adapted to make the relays sluggish in resuming their normal position when once energized.

L and M represent condensers.

L and L represent two conductors or members of the trunk circuit, connecting the repeater with the central olfice switches, which switches are adapted to automatically extend and complete the connection.

J and K represent line relays controlling the operation of an automat1c switch. lit should be understood that relays J and K represent corresponding relays associated with different switches involved in establishing a connection.

A source of current supply, preferably a storage battery, is shown at 2 and at 1 an earth connection.

An examination of the patents previously referred to will show that the automatic switches of the general type covered by them, are adapted to select, but not engage in electrical contact, the trunk or line terminals, corresponding to the digit called by the calling station, when the corresponding number of successive grounds are placed upon one of the wires of the line circuit. This wire is usually known as the vertical side of the line. The switches are caused to engage in electrical contact the trunk or line terminal selected, when a ground is placed upon the opposite or remaining line wire. This wire is usually called the rotary side of the line. In the accompanying drawing. the conductor L may be considered the vertical side of the line and conductor L the rotary side of the line. Relay J in each switch involved in a connection, will then control the selective powers of the switch and relay K the power of the switch to engage in electrical contact the trunk or line terminal selected by relay J. After the called line terminals have been picked up the call bell at the called station is caused to ring when the vertical side of the line is grounded. A further examination of the patents will show that the release of an established connection is accomplished by simultaneously grounding both sides of the calling line. It will therefore be seen that my improved repeater circuit must be capable of supplying to the vertical wire of the line, a series of grounds corresponding to the digit called by the calling station and at the end of each such series must also be capable of supplying a ground to the rotary side of the line. After the selection of the called line terminal, the repeater must be capable of grounding the vertical wireof the line whenever the ringing key at the calling station is depressed. At the end of conversation when the receiver is replaced greases upon the hookswitch at the calling station, the repeater must be capable of simultaneously grounding both sides of the line for a moment. In nearly all of the recent automatic telephone installations, a small switch known as a line switch has been installed. The function of this switch is to connect the calling subscriber with an idle selector, thereby reducing the number of selectors required since it is safe to assume but a small portion of the lines will be used at any one time. In one type of central oflice equipment now widely used, the line switch is caused to connect the calling line with an idle selector by means of a preliminary ground momentarily placed upon the rotary side of the calling line, just prior to the sending of the first series of impulses over the vertical side of the line. In my improved repeater circuit, this is accomplished by momentarily grounding the rotary side of the line immediately following the removal of the receiver from the hookswitch. As before indicated, the call receiving branch of my repeater circuit is adapted to receive calls from a calling station equipped with a calling device, consist ing of a pair of contact springs, adapted to rapidly open and close the line circuit as many times as indicated by the digit called. For example, when the digit eight is called, the line circuit is rapidly opened and closed eight times.

From the preceding paragraph it may be said that that function of my improved repeater is to receive impulses from a calling telephone station equipped with a calling device adapted to make and break a metallic line circuit and then to transmit the impulses thus received to the central oflice apparatus, first by grounding one side of the line herein called the vertical side of the line, as many times as the line circuit is broken at the calling station, depending upon the digit called, and then momentarily grounding the other side of the line herein called the rotary side of the line. Upon completion of the calling of the desired numher, the repeater must be capable of grounding the vertical wire each time the ringing key is depressed at the calling station. Upon the permanent opening of the calling line circuit, which takes place when the receiver is replaced upon the hookswitch, the repeater momentarilyigrounds both sides of the line toward the central oliice, thereby releasing the connection.

The operation of my improved repeater circuit is as follows: When the receiver is removed from the hookswitch at station A, the line circuit is closed, current flowing from 1, through one winding of relay D, one winding of relay C, L calling device contacts 3, transmitter, hookswitch contacts, primary winding of induction coil, I), re-

' cial purpose.

maining windin' of relay C, remaining winding of relay battery 2, to the earth 1. The current thus caused to flow energizes relay C. Relay D remains inert, its winding being differentially connected for this spe- The operation of relay C opens contact between 7 and 8, 5 and 6, and causes contact to be made between 5 and 4, thus energizing relay F and momentarily relay H through contacts 23 and 24. Relay F closes contact between 20 and 21, 26 and 25 and breaks contact between 21 and 22 and 24 and 23. The momentary operation of re-- lay H grounds conductor L", from 1, through 29, 30, 32, 31 to L. The object of this preliminary ground is to trip the line switch if one is used, as previously described. When relay H resumes its normal position, the earth connection is removed from conductor L by the opening of contact between,

31 and 32. The repeater is now ina position to receive and transmit impulses from the calling station. As before stated, the impulses received from the calling station consist of a series of interruptions of the calling line circuit and are produced by operating the calling device. The number of times the line circuit is opened and closed corresponds to the digit called. The speed of these interruptions is so adjusted as to permit relay C to follow them, but not the sluggish relays F. In this way, the repeater is held in its operative condition during calling. Assume now that station A calls the first digit of the desired number. Relay C resumes its normal position as many times as the line circuit is broken between the calling device contacts 3. Each time relay C resumes its normal position, it closes contact between 5 and 6 and between 7 and 8 and breaks contact between 4 and 5. The closing of contact between 7 and 8 operates sluggish relays G and H, a circuit being closed from 1 through 7, 8, 26,25, windings of G and H, 2 to 1. Relays G and H being sluggish, do not chatter when relay C operates in response to the impulses received from the calling device 3. The closing of contact between 5 and 6 causes a ground to be placed upon conductor L thereby causing current to flow from 1, through 5, 6, 21, 20, 12 and 13, conductor L winding of J, 2 to 1. As before stated,-relay J controls the selective powers of the automatic switch. The result.

is that the switch is caused to proceed in the selection of the number called, each time a ground is placed upon the conductor L After the calling device at station A has completed an operation, that is, after it has sent a series of impulses in response to the digit called, the line circuit through the calling station, A, is again permanently closed through contacts 3. The result is that relay C remains energized. The permanent open- -$5 ing of contact between 7 and 8 allows relays the various relays.

G and H to resume their normal position.

The adjustment of relay G is made such that it resumes its normal'position before relay H. Therefore, there is an interval during which a ground is placed 'on conductor L, from 1, through 29, 30, 32, 31 to L. Relay 'K is thus energized. As before stated, this relays in the selectors and in the connector. I

After the final digit has been called, ringing key R at stationA is depressed, thereby grounding both sides of the calling line. The result is that the differential relay D is unbalanced by the short circuiting of its earthed winding. The unbalancing of the relay causes it to operate, and in so doing breaks contact between 9 and 10 and closes contact between 10 and 11. This results in the operation of relay E, which relay remains locked up during the remainder of the connection and grounds conductor L from 1, through 29, 30, 32, 35, 11, 10, 14, 13 to Li. The operation of relay E is caused by the closing of a circuit from 1 through 10, 17, 16, winding'of E, 2 to 1. The energizing of relay E opens circuit between contacts l6 and 17 and closes the locking circuit from 1, through 5, 4, 15, 16, .winding of E, 2 to 1. The operation of this relay also connects the calling line branch of the repeater to the called line branch of the repeater. This is effected by the making of contact between 13 and 14 and between 18 and 19.

When ringing key R is allowed to assume its normal position, relay D is denergized, thereby removing the ground connection from conductor L relay E, as before stated, remains energized until released at the end of the connection. Each time the ringing key R is depressed, a ground is similarly applied to conductor L thus operating line relay J of the connector involved in establishing the connection, thereby energizing the ringing relay of the connector and causing the call bell at the distant station to ring. When the called station answers, conversation may be carried on. The function of condensers L and M is to transmit the high frequency voice currents but not the direct current acquired for the operation of At the end of conversation, the receiver at the calling station is replaced upon the hookswitch, thus permanently opening the calling line circuit. Relay C now resumes its normal position, breaking contact bet-ween 5 and 4 and making contact between 5 and' 6 and 7 and 8. This opens the circuit through both relays E and F, allowing them to resume their normal position. Prior to the deenergizing of relay F, a circuit is momentarily established from 1, through 7, 8, 26 and 25, winding of G, Winding of H, 2 to 1. Relays G and H now operate and remain energized until con tact is opened between 25 and 26, whereupon both relays resume their normal position. As before stated, however, relay G resumes its normal position first. Therefore, during the interval between the falling back of relay G and relay H, a ground is placed on both sides of the line toward the central otiice, in one case from 1, through 29, 30, 32, 31 to If and in the other case from 1, through 5, 6, 21, 22, 28, 27. 34, 33 to L The result of this simultaneous grounding is that relays J and K are simultaneously energized, and as before stated, this simultaneous action results in the disconnection of the automatic central oiiice apparatus. When relay H finally resumes its normal position, the ground is removed from both conductors L and L and the circuit of the repeater resumes its normal position.

One of the principal advantages of the repeater circuit just described, lies in the fact that the line conductors L and L in the calling line branch, and the line conductors L and L in the called line branch are not engaged in electrical connection during calling. Experience has shown that Where this is not the case, the charging and discharging of condensers L and M which occurs when the calling line circuit is made and broken, seriously interfered with the transmission of sharp and clear impulses to the central office apparatus.

Having thus described the invention, what is claimed as new is:

1. In a telephone exchange system, a line circuit, a repeater circuit, means for operating the repeater circuit. a trunk circuit terminating in an automatic switch for connecting to a called substation, condensers, and means for connecting the line and trunk circuits through the condensers to establish a talking circuit after the completion of the connection with the called substation.

2. In a telephone exchange system, a line circuit, a repeater circuit. means for operating the repeater circuit, a trunk circuit terminating in an automatic switch. condensers, and means operated upon the grounding of one side of the line at the subscribers station for connecting the line and trunk circuits through the condensers to establish a talking circuit, the last means being operable by the operating means of the repeater circuit.

3. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuitterminating in an automatic switch, means .responsive to a ground impulses over meaeve for operating the repeater circuit comprising a calling device and ringing device, con densers, and means operable by the ringing device aforesaid to connect the line and trunk circuits through the condensers to establish the talking circuit.

4.. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, and a relay adapted to be energized by the ringing device to connect the line and trunk circuits to establish a talking circuit.

5. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, condensers, and a relay adapted to be energized by the ringing device to connect the line and trunk circuits through the condensers to establish a talking circuit.

6. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit compris ing a calling device and ringing device, and means operable by the ringing device aforesaid to connect the line and trunk circuits to establish the talking circuit.

7. In a telephone exchange system, line and repeater circuits, a trunk circuit terminating in an automatic switch, a calling device to operate the repeater circuit, and means comprising a ringing device to ground the line circuit and thereby connect the line and trunk circuits to establish a talking circuit.

8. In a telephone exchange system, line and repeater circuits, a trunk circuit terminating in an automatic switch, a calling device to operate the repeater circuit, and means comprising a ringing device to ground the line circuit to simultaneously ring the called subscriber and connect the line and trunk circuits to establish a talking circuit, and subscribers lines connected with the automatic switch.

9. In a telephone exchange system, the combination of line and repeater circuits, a trunk circuit leading to an automatic switch, and said repeater circuit including means responsive to initial closure and subsequent prolonged closure of the line circuit to ground one member of the trunk circuit, and

prolonged interruption of the line circuit, to ground both members of the trunk circuit.

10. In a telephone exchange system, the combination of a line circuit, means for clos ing the line circuit. means for momentarily interrupting said circuit, a repeater circuit, a trunk eircui, an automatic switch connected to said trunk circuit and operable by the trunk circuit,

means in the repeater circuit responsive to said interruptions of the line circuit for grounding one member of the trunkcircuit, and means coiiperating with the means just mentioned on an initial closure of the line circuit for momentarily grounding-the other member of the trunk circuit. A 11. In a telephone exchange system, the combination of a line circuit, means for closing the line circuit, means for momentarily interrupting said circuit, a repeater circuit, a trunk circuit, an automatic switch connected to said trunk. circuit, and operable by ground impulses over the trunk circuit, means in the repeater circuit responsive'to said interruptions of the line circuit for grounding one member of the trunk circuit, means cooperating with the means just mentioned on an initial closure of the line circuit for momentarily grounding the other member of the trunk circuit, and means responsive to subsequent prolonged closure of the line circuit for grounding the last mentioned member of the trunk circuit.

12. In a telephone exchange system, the combination of a line circuit, means for closing the line circuit, means for momentarily interrupting said circuit, a repeater circuit, a trunk circuit, an automatic switch connected to said trunk circuit and operable by ground impulses over the trunk circuit, means in the repeater circuit responsive to the initial closure of the line circuit to ground one member of the trunk circuit, means in the repeater circuit responsive to said interruptions of the line circuit for grounding one member of the trunk circuit, and means responsive to subsequent prolonged closure of the line circuit for grounding the other member of the trunk circuit.

13. In a telephone exchange system, the combination of a line circuit, means for closing the line circuit, means for momentarily interrupting said circuit, a repeater circuit, a trunk circuit, an automatic switch connected to said trunk circuit, and operable by ound impulses over the trunk circuit, means in the repeater circuit responsive to initial closure of the line circuit to ground one member of the trunk circuit and responsive to prolonged interruption of the line circuit to ground both members of the trunk circuit, means in the repeater circuit responsive to said interruptions of the line circuit for grounding one member of the trunk circuit, and means responsive to subsequent prolonged closure of the line circuit for ounding the other member of the trunk clrcuit.

14. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, and differentially and inductively wound relays connected in series and bridged across the line circuit, so that the latter relay is responsive to a closure of said line circuit, and the first-mentioned relay responsive to agrounding of the said circuit by the ringing device.

15. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, differentially and inductively wound relays connected in series and bridged across the line circuit, so that the latter relay is responsive to a closure of said line circuit, and the first-mentioned relay responsive to a grounding of the said circuit by the ringing device, and a relay adapted to be energized by the ringing device to connect the line and trunk circuits to establish a talking circuit.

16. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, condensers, differentially and inductively wound relays connected in series and bridged across the line circuit so that the latter relay is responsive to a closure of said line circuit and the first-mentioned relay responsive to a grounding of said circuit by the ringing device, and a relay adapted to be energized by the ringing device to connect the line and trunk circuits through the condensers to establish a talking circuit.

17. In a telephone exchange system a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, condensers, diflerentially and inductively wound relays connected in series and bridged across the line circuit so that the latter relay is responsive to a closure of said line circuit and the first-mentioned relay responsive to a grounding of said circuit by the ringing device, and a relay adapted to be energized by the ringing device through the intermediation of the differential relay to connect the line and trunk circuits through the condensers to establish a talking circuit.

18. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, and a differentially wound relay bridged across the line circuit, not responsive to closures of the line circuit, but responsive to a grounding of said circuit, whereby one side of the trunk circuit is grounded.

19. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device,

condensers, a differentially wound relay bridged across the line circuit, not responsive to closures of the line circuit, but responsive to a grounding of said circuit, whereby one side of the trunk circuit is grounded, and a relay adapted to be energized by the ringing device to connect the line and trunk circuits through the condensers to establish a talking circuit.

20. In a telephone exchange system, a line circuit, a repeater circuit, a trunk circuit terminating in an automatic switch, means for operating the repeater circuit comprising a calling device and ringing device, condensers, a difl'erentially wound relay bridged across the line circuit, not responsive to closures of the line circuit, but responsive to agrounding of said circuit, whereby one side of the trunk circuit is grounded, and a relay adapted to be energized by the ringing a ger device through the intermediation of the difierentially Wound relay to connect the line and trunk circuits through the condensers to establish a talking circuit.

21. In a telephone exchange system, the combination of line and repeater circuits, a trunk circuit leading to an automatic switch, and a repeater circuit including means responsive to initial closure of a line circuit to momentarily ground one member of the trunk circuit and responsive to a prolonged interruption of the line circuit to momentarily ground both members of the trunk circuit.

In testimony whereof I afiix my signature in presence of two witnesses.

GERALD DEAKIN.

Witnesses:

PAULINE J. GLAUCH, E. A. MCCANN.

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