US1594587A - Telephone system - Google Patents

Description

Aug. 3 1926.

G. BABCOCK TELEPHONE SYSTEM Filed Jufie 11, 1921 2 Sheets-Sheet 1 Aug. 3, 1926. v 1,594,587

G. BABCOCK TELEPHONE SYSTEM Filed June 11, 1921 2 Sheets-Sheet 2 Patented Aug. 3, 1926.

UNITED STATES PATENT OFFICE.

TELEPHONE SYSTEM.

Application filed June 11, 1921.

My invention relates to telephone systems, and more particularly relates to systems in which the service to the subscribers is metered through the use of reverse ourrent flow over the calling line. The present application is specifically concerned with novel means for securing the reversals of current, and for applying them to the calling line. The current reversing device, which is the subject of certain of the claims hereafter, is not limited to the employment in a telephone system, or, if employed in a telephone system, is not limited to the specific method of connection and application which I have specifically described in the following specification.

In carrying out the matter of metering a telephone service, I have devised a system of current reversal operating on meters installed on the subscribers premises I have developed a number of different methods and suitable means for securing the reversal of polarity upon the calling line, all of which have proven satisfactory, but of a generally more expensive construction than I find possible according to the present invention.

The primary aim of the present invention is to provide. a simple, positive and inexpensivemeans for securing reversals of current flow suitable for actuating tclechronometers on telephone lines, and the like. For this purpose, it is necessary that the .change in potential over the telephone line he made quickly and positively, without any change or sharp interruption of current flow, which would be exceedingly disagreeable and highly objectionable in a telephone system. According to the present invention, I provide a resistance, or pair of resistances, for each direction of current flow, these resistances, or pairs of resistances, being connected to the answering end of the cord circuit constantly, through a potentiometer or \Vheatstone bridge connection, so that, by reducing a resistance, or pair of resistances, the polarity of the terminals of the pole-changing device will be reversed.

The opposite resistances in the Threatstone bridge are arranged mechanically side by side, and mechanically such opposite pairs of resistances are compressed and released alternately, so that the potential of the terminals is shifted quickly and Serial No. 476,713.

smoothly from one time to another, thereby causing reversal of current.

. In order to teach those skilled in the art in the manner of constructing and racticing my invention, I shall now descri e an embodiment of the same, as illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a diagrammatic lay-out of a telephone system embodying my invention;

Figures 2 and 3 illustrate the development of the basic idea involved in my pole-changmg device;

Figure 4 is a" fragmentary diagrammatic 1loaylout of the pole changer or Wheatstone Figure 5 is a side elevational View, partly diagrammatic, of the mechanical linkage for operating the compression rheostat;

Figure 6 is a plan View, partly in section, showlng a modified form of the same; and

Figure 7 is a fragmentary illustration of a polarized relay which is employed to control the actuation of the compression rheostat.

In the system employing my invention, I dispose at the subscribers stations A and B, in conjunction with the usual telephone apparatus, a call registering device 1 adapted to be operated by reversals of current. The particular meter which I prefer to employ is described in my copending application, Serial No. 476,712, filed June 11, 1921. This meter is characterized by the use of two series coils connected in the two sides of the talking line, and provided with suitable polarizing means and counter-actuating mechanism, whereby a complete cycle of the reversal of current is required for the actuation of the starting mechanism.

Any other suitable metering device operating upon reversal of current may be employed, as the present application relates more particularly to the manner of and means of securing current reversal.

The calling station A comprises the usual transmitter 2, receiver 3, induction coil 4,

hook switch 5, and ringer or call hell 6. The

station is connected to suitable terminals at central over the line wires 7 and 8, which line wires are provided with connections to the central battery 10, for supplying normal polaritof current over the line. The line is provided at central with a suitable answering plug 17 for cooperating with thehline and multiple jacks, 1n makingconnections and inter-connections. The answering plug 16 is connected to the talking strrands 18 and 19, and is provided with a third conductor 20 for controlling the actuation of the cut olf relay 13, and the sleeve relay 21. A listening key 22 for placing the operators talking set 24 in communication with the strands 18 and 19 is also provided. At the ringing end of the cord circuit, the plug 17 is connected to the talking strands 25 and 26, and is also connected tothe third conductor 27, which serves to energize the line out off relay 13' of the called line 7' 8 and the sleeve relay 27 The operator is provided with a ringing key 28, which 15 adapted to connect the ringing generator 29,

or other source of ringing current, to the conductors of the called line.

While I have illustrated a three strand cord circuit in the particular embodiment which I have elected todescribe, it is to be understood that the invention is not limited in any manner to the em loyment of a three-' strand cord circuit, an myillustration of the same is for the purpose of clearly il'-' lustrating my invention in as simple a manner as possible.

The answering end of the cord circuit is" supplied with battery from the central source 10 over suitable connections which will be described later, and which include the answering supervisory relay 30, which, in connection with the sleeve relay 2], controls the supervisory signal 31. In a similar manner, battery is fed to the ringing end of the cord circuit from the central battery over suitable connections, in this case-wires 32, winding 33, and conductor 35, to the tip strand 25, and from ground or negative side of the battery, over the winding 36 of the superiisory relay 34, conductor 37, to the ring or sleeve strand 26 of the ringing end of the cord circuit. The potential upon the ringing end of the cord circuit always remains in the same direction, due to the connections above described, so that no reversals of current upon the called line occurs, the calling line only being charged for the call.

The pole changing device 38 comprises two gtirs of compression resistances, R R and 2 R, between which battery is connected over the conductors 39 and 40, and between which pairs is an actuating memher in this case a bar 41, connected to a suitable armature for the operating magnets 42 and 43. The circuits for the actuating magnets 42 and 43 are controlled by the polar.- ized relay 44, and the time controlled-relay 45. The relay 45 is in turn governed by the time controlled circuit breaker and maker 46, which includes the cam wheel 47 and the contacts 48 for periodically closing a circuit over the wire 49 for the winding of the controlling relay 45. The controlling relay 45 has a pair of contacts 50, which close a circuit from battery over the wire 51 to the terminals of the two actuating magnets 42 and 43, the other terminals of which magnets are connected respectively to contacts 52 and 53 of the polarized relay 44. A movable armature contact 54 is connected to ground, and depending upon the polarity prevailing upon the terminal wires'56 and 57 of the pole changing device 38, the armature 54 will close contact with the corresponding one of the contacts 52, 53. The polarized relay 44 has a Winding 58, which is bridged across the terminals 56 and 57 by means of wires 60 and 61. The polarized relay 44 is thus subjected to the'same polarity as that existing upon the calling line, and the shifting of the polarity upon the calling line controls the circuit of the actuating relays 42 or 43.-

In order to make more clear the operation of the pole changer, I have shown diagrammatically in Figure 4, a detached and simplified diagram of the connections showingthe relations of the resistances in the circuit. The battery 10 is connected to the .common terminal 62 of the resistances R and R and the common terminal 63 of the resistances R and R The terminals 56 and V57,o f the pole-changer, which lead to the talking strands 18 and 19, respectively, through the supervisory relay 30, are connected to the common points 64 and 65, respectively, these points being the connecting points of the resistances R and R and R and B, respectively. The resistances R and R are mechanically compressed together, these resistances comprising carbon piles, and the resistances R and R are actuated simultaneously, these resistances also comprising carbon piles. It can now be seen that if the resistances R R R and R are all equal, no difference of potential of the terminals 56 and 57 will exist. v It, now, the resistances R and R are simultaneously compressed to reduce the value of the same, the terminal 56 will exhibit a strong negative potential, and the terminal 57 will exhibit a strong positive potential, as indicated in Figure 3. It, now, the pressure on resistances R, R is relaxed. and simultaneously the pressure of resistances R R" is increased, the terminal 56 will exhibit a positive potential, and the terminal 57 a tances are connected in series with the bat-.

tery 10. The other terminal 56 of the circuit is connected between the resistances R and R Assuming that the resistances It and R are of a variable type, such as carbon piles, or of any other suitable character, so that they may be gradually increased or decreased, and assuming that one of the resistances is increased while the other is decreased, it will be seen at once that by a shifting of the value of the resistance in said circuit, the normally equipotential points to which the terminals 56 and 57 are connected will change.

It is to be noted that in this potentiometer circuit, the maximum voltage which can be secured is only half of that of the battery, and if such a system were employed the difiiculty of maintaining proper battery connections and proper voltages upon the lines and relays would be pronounced.

I have conceived, therefore, that this difficulty might be remedied by employing two potentiometer circuits connected together, whereupon the full voltage of the battery might be employed upon the terminals, and I have therefore shown in Figure 3 the transitional stage between the conception of Figure 2 and the conception of Figure 4. In this construction I employ two separate batterics, 10 and 10 in separate potentiometer circuits, S6 and 86", respectively, and connect these batteries together at their neutral points; whereupon, I am able to take the full potential of the battery from the terminals 56" and 57". The potentiometer circuit 86 contains resistances R and R while the potentiometer circuit 86" includes the resistances t and R. Since the two battcrics are connected in the same direction, perform the same function, and the added voltage of two halves is always provided, it is possible to dispense with one of the batteries, wereupon the circuit assumes the form shown in Figure 4, namely, a \Vlueatstone bridge having substantially equal resistances in all four of the arms. It is perhaps inadequate to state that the resistances of all four arms is equal, since the desired construction is that the resistances will have substantially. the same characteristics through the various stages of compression or release which they must oc cupy. It is not essential that these resistances be absolutely balanced at all times, but a condition of balance is desirable. The Wheatstone bridge is in reality a double potentiometer circuit.

I consider that this constitutes a novel process of producing a reversal of 'potential upon a telephone circuit, and am claiming the same accordingly.

The particular means by which I accomplish the reversal mechanically is illustrated in Figure 5, and a modification thereof illustrated in Figure 6.

In Figure 5 I provide a walking beam (36, each arm thereof having connected thereto a solenoid plunger 67, 68, the co-operating solenoids 69 and 70 corresponding to the actuating magnets 42 and 43 ofFigure 1. Each arm of the walking beam 66 is connected pivotally, as at 71 and 72, to a co-operating link or strut 73, 74 respectively, for creating a powerful thrust upon the compressible resistances R R These resistances preferably comprise sleeves of insulation containing carbon granules, or other compressible resistance material, such as discs or wafers of carbon, or the like. As shown in Figure 5, the thrust rods 73 and 74 operate through levers 75 and 76, instead of'bearing directly upon the ends of the resistances R R These levers 75 and 76 are pivoted at their central portions, as shown at 77 and 78, and serve merely to form a more compact arrangement of the device. It will be seen at once that the walking beam 66, in connection with the thrust. rods 73 and 74, form a pair of toggle arms of relatively great power for imposing suitable pressure upon the carbon piles R R I wish to call attention, in this connection, to the fact that the final movement of the toggle mechanism is particularly powerful, both because of the increased power of the toggle as the same approaches a straight line, and also because of the increased power of the solenoid, or other electromagnet, when attracting its coreor armature 67' 68. Any

ltltl llO desired characteristic may be obtained by suitably designing the ratio of the toggle and the characteristic of the operating magnet or solenoid. In addition, the pressure will remain upon the piles until the toggle is broken.

In Figure 6 I have shown a modified form of pole changer, in which I employ a straight actuating bar 41, which serves as an armature for the two operating magnets 42 and 43; in this case, the magnets are of the shell type, in which the magnetic circuit is closed through an outer magnetic shell 79, and through the magnetic bar 41, so that the powerful pull upon the said armature 41 is secured when the winding of the corresponding magnet is energized. The

armature'41 is insulated from electrical contact with the resistances by buttons of insulating material as indicated at 80.

In Figure 7 I have illustrated the manner in which I construct the terminals of the polarized relay 44. The contacts are made by the employment of small rollers of nonarcing material pivoted upon the ends of suitable springs, these rollers adapted when brought into contact to roll slightly, and thus constantly change the point of contact between them, thereby greatly prolonging the life of the same.

I shall now describe briefly the operation of a system embodying the invention. Assuming that the party at the sub-station A desires to be connected to the party at the sub-station B: The receiver 3 is raised, placing the transmitter and receiver in circuit, and operating the line signal 14 to call attention to the fact that the party at the station A desires to make a call. The operator makes connection with the answering plug 16 replacing the line signal and connecting the strands 18 and 19 to the line wires 7 and 8. At the sametiine, current of the prevailing polarity flows out over the talking strands 18 and 19, and over the line wires 7 and 8, and supplies talking current to the instruments at the substation A. The operator, through the medium of the listening key 22, receives the order for connection from the party at the sub-station A, and assuming that the line connecting with the station B is desired, the operator presses the terminals of said line and proceeds to make the connection. The ringing key 28 is actuated to project the ringing current over the called line, and when the party at the sub-station B answers, current flows in-normal direction over the line of the called party, and conversation between the parties may be carried on.

The operation of the pole changer continues at all times, and in the system I have illustrated th calling party is charged for all of the time consumed in making a connection and consummating the conversation. If desired, the calling party may be charged for only the time during which connection between the two parties is established .by cutting the terminals of the relay 30 through the contacts of the supervisory relay 34, so that until the calling party responds, normal polarity of current prevails upon the calling line. Since both methods of operation are known, I do not consider it necessary to illustrate the same in detail.

The operation of the pole changer is as follows: The time controlled cam 47 rotates continuously, intermittently making contact at the contacts 48 to close the circuit of the relay 45 over the Wire 49. The closing of the contact 48 is only momentary,

magnet 43, wire 84, contacts 53, to ground.

Thereupon, the resistances R and R are compressed, and the pressur on resistances R and R relieved, reversing polarity upon the terminals 56, 57, and causing the armature 54 of the polarized rcla 44 to swing to the alternate contact 52. efore the armature 54 arrives at the contact 52, the cir-' cuit at the contact 50 is opened until the time wheel 47 again closes the contact 48 to energize the relay 45.

If desired, a locking circuit for the relay 45 may be closed when the contacts 50 are closed, this locking circuit being opened by the throw of the armature 54 upon the contact on which it previously rested. I

A changeof polarity occurring on the calling line from positive to negative, and back to positive, or vice versa, causes an actuation or registration .upon the meter 1 at the calling station. If desired, the meter may be actuated by a reversal of current only, that is, from positive to negative, or vice versa, but I prefer the use of a meter which requires a complete cycle of alternation for registration of a count thereupon.

1 do not intend to be limited to the details of construction shown or described.

I claim:

1. In combination, a telephone line, a closed battery circuit including two substantially similar variable resistances across which substantially the full voltage oi the battery is impressed, a first connection from one side of said line to said circuit at a point between said resistances, and a second connection from the other side of the telephone lineto said circuit, said second connection being made at a. point normally equi-potential with the first point, and means for automatically increasing the resistances.

2. In combination, a tele )hone line, a closed battery circuit including two substantially similar variable resistances across which substantially the full voltage of the battery is impressed. a first connection from one side of said line to said circuit at a point between said resistances, and a second connection from the other side of said line to said circuit, said second connection being made at a point normally equi-potential with the first point, and means for simultaneously incrcasing one resistance while reducing the other, and vice versa.

3. In combination, a. telephone line, a

closed circuit having a source of current and including two substantially similar variable resistances across which substantially the full voltage of the source is impressed, said resistances comprising carbon piles, a first connection from one side of said line 'to said circuit at a point between said resistances, and a second connection from the other side of said line to said circuit, said second connection being made at a point normally equi-potential with the first point, and means for increasing the pressure on one carbon pile while reducing the pressure on the other carbon pile.

4. In combination, a telephone line, a closed circuit having a source of current and including two substantially similar variable resistances across which substantially the full voltage of the source is impressed, a first connection from one side of said line to said circuit at a point between said r'e-- actuating magnet for increasing one resis-v tance with respect to the other, and vice versa. 7

5. In combination, a telephone line having a call meter adapted to be operated by reversals of current, means for supplying current to the meter, said means comprising a cord circuit having a pole changing device for supplying current to the talking strands of the cord circuit, said pole changing device comprising a pair of carbon piles adapted to be periodically compressed alternately.-

6. In combination, a telephone line having a meter adapted to be operated by current reversals, a switching circuit at central connected to means for supply talking current to the line and to the meter, said means comprising a potentiometer circuit containing two variable resistances, and means for periodically and alternately varying said resistances, said means being adapted to vary said resistances smoothly, whereby no sharp change of potential is created on the talking circuit.

In combination, a telephone line, a potentiometer circuit comprising two variable compressible resistances, terminals leading to said telephone line connected to said'potentiometer circuits, electromagnetic means for varying said resistances alternately, and time controlled means governing the actuation of said electromagnetic means.

-8. In a telephone system, a talking line, means for supplying current periodically in reverse direction over said line, said means comprising a potentiometer circuit including a pair of non-interruptible variable resistances, a pair of electro-magnets for alter-.

nately varylng said resistances, a time controlled circuitco-ntr'oller for periodically actuating one of said electromagnets, and a polarized circuit changer for determining the electromagnets to be actuated.

9. In combination, a telephone line having a call meter adapted to be actuated by reversals of current, polarity means for supplying periodically reversed current over said line, said means comprising a link circuit having a pole changing device for sup-' plying current to the talking strands of the link circuit, said pole changing device comprising a pair of carbon piles adapted to be periodically compressed and released alternately, and means for periodically compressing and releasing said piles.

10. In combination, a telephone line having a meter actuated by variations of current, a potentiometer circuit for supplying talking current to the line, said circuit comprising a pair of compressible variable re-' sistances and means for alternately compressing said resistances.

In witness whereof, I hereunto subscribe my name, this 2nd day of June A. D., 1921.

GARRISON BABOOCK.

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