USRE10193E - Best available cop - Google Patents

Description

G. DINFREVI LLE.

Assignor to THE WESTERN UNION IELEGRAPH 0014mm. DUPLEX TELEGRAPH.

N0. 10,193. Reis'sued Sept. 5, 1892.

ATTORNEY to the entire length of theline.

vUrn'rnn STATES PATENT OFFICE.

'cnonens ninrnnvrnnn, or NEW YORK, N. Y.,'nss1cnon TO THE WESTERN UNION, TELEGRAPH SOMPANY, OF SAME PLACE.

DUFLEX, TELEGRAPj-l,

SPEQIFICATION formingpart of Reissued Letters Patent No. 10,193, dated September 5, 1882 Original No. 23B,094,dated February 22, 1881. Applicationifor reissue filed April 17, 1882. v

' To all whom it may concern:

neously from the opposite ends of one and the same line-wire.

The general object of the invention is to prevent false signals,which are ordinarily produced upon the receiving-instrument at the transmitting or home station by when are technically known as the current of static charge and the 'cnrrent of static discharge.

It is a well-known fact that when an insulated telegraph-line of considerable length having its remote end connected with the earth is suddenly placed in connection with one pole of a battery whose opposite pole is connected with the earth a powerfulcurre t of electricity of momentary duration flows into the conductor, which is termed the current of staticcharge; and this phenomenon is due to the fact that the line will take a static charge first at a point next adjoining the battery-pole, and thence at one succeeding point after another along the entire length of line to the distant end. As each portion oflength of the line stores an appreciable quantity of electricity in the course of its static charge,

that part of the'circuit in which a current actually flows increases in length, and at each instant terminates in that point which is re oeiving its static charge. At most, very little current will be set up in a line beyond a part which has not received such a charge. Thus when a battery is first placed to line its rapidly-increasing length of circuit is at first very short, and its resistance is but little in excess of the internal resistance oi'the battery and associate artificial resistances. The battery, therefore, at thefirst instant of connecting the line is as itupon a short circuit, and the electrical potential of points near the cattery is much lower than when the circuit is increased The electrical potential, therefore, at a point near the hat a given point will remain constant from the connecting the line to the battery, while the potential only becomes normal and greatest after the line is fully charged throughout its entire length. If the line has "no capacity for receiving a static charge, the potential at instant of connecting theline and the battery until its removal.

. The conditions requisite for the simultaneous transmission of signals in opposite directionsare, first, the receiving'instrument ateach station must remain at all times in connection with the line; second, signals transmitted by thekey at. either end otthe line must produce no effect upon the receiving-instru ment at the same station. 'The difiicultics which tend to prevent the fulfillment of the latter condition especially arise principally from the effects of the currents of staticcharge and of static discharge.

In order to preventthereceiving-instrument at the home station from being affected by the .outgoingcurrents from the home battery,which are designed to produce signals at the distant station, a device commonly known as an artificial line is usually employed, which is simply a derived circuit branching from the main 80 line at a point nearits junction with the transcutting-key, which goes directly to earth, or, what is the same thing, returns to the other pole of the home battery. This circuit is provided with artificial resistances or rheostats, by '8 5 means of which its .totalresistance may be' made equal to that of the main line. This ar, rangement enables the home receiving-instrument to be placed in abridge-wirejoining the main and artificial linesat points of equal potential, and which points are therefore neutral with reference to outgoing currents; or the receivinginstrunient may be provided withtwo equal and opposing helices, one of which is included in the main and the other in the artificial line. It has, however, been found by e perience that although the resistances of the main and artificial lines may be the same, their capacity for receiving a charge may be very ditfcrent, the main line usually having a great capacity and the artificial line little or none. Thus at the moment of commencing the trans- BEST AVAILABLE COP finial line momentarily and simultaneously;

mission of a'signal, asstated in the foregoing, with the act of charging the main line from the electricalpotential-at the endof the bridge either pole of the battery, whereby the etch- ,inthe main li'ncwill be nearlyzero, while at tial in the artificiallineat one end of the iitlge 7c *the other end of thebridge in the artificial line may be assimilated to the decreased potential 5 the potential will be'high, whereupon-a strong in the main line at the other extremity of the current will-flow through the bridgc'from the bridge. A portion of the artificial-line resistpoin't'of high to'the one of low potential, and ance is. withdrawn by the same movement of thereby a-false signal is produced upon the rethe transmitter which serves to connect and y coining-instrument; also,wnpon disconnecting disconnect the main and artificial line with a xo-apole of abatlery fro uilinecolleennecting'it battery-pole, whereby the potential of the arto earth an instantaneous current of opposite tificial line at the extremity of the bridge polarity with flow to earth, a portion of which automatically regulated upon connection and willjpass' through the: bridge and causea false disconnection-of a battery-pole and the main 8o signal. 1 v y I h line. The transmitter at the Yeiyinstantthat 15 The particular object of my invention is to one battery-pole is connected to and the op- I establish an equalityofelectrical potential in posite pole is disconnected from theline simulthemain and artificial lines at the two extremitaneously closes an auxiliary circuit around ties of the bridgeduring the periods of static any adjustable portion cfthe artilicial-iinere' 3 Y charge auddischarge, as well as when the main sistance. The auxiliary circuit thus conneetaq 'liue is'charged' throughout its entire length. ,(id is retainedclosed inonientarilynend while if anequalityof potential be maintained bethe main lineis receivingits stnticcharge from tween the extremities of the bridge under all thebattery-pole just connected, and during the conditionsofoperation of the transmitting-insimultaneous static discharge, due to the op stl'ument 'noourrentwillbe setupin the bridge posite pole,which is disconnected at the same '15and'nofalse-signals willbe produccdupon the time, when it is broken, and the auxiliary associatedreceiving-instrument; and to this circuit'remains broken until the pole of the end my ini'enlion consists in a method or battery, previously connected to line, is re menus"tbri'docreasin'g the potential'in the artimoved therefrom and the opposite pole is 95 ficial line a the extremity of the bridge to again CODIlBOCHl WlIGLl itis againmementarily joxsnch an'extent that there slrallbe a substanclosed and retained closed during a period tial eqn'ality fnf potential atbo'th extremities of equal to'that ofthe augmented static charge, the. bridge at the instant themain'line is reand is then broken.

- calving its static charge andduring its static For the purpose of more elearlyexplainieg we discharge. 11f one 'pole'of a battery be re; my invention, I'will briefly-refer to thence v "-1no.\ed from the linejat the same instant an struction and mode of cperation of one form of opposite" one iscouuectcd thereto, the current telegraph apparatus forthe simultaneous trans- Pot static discharge due to one will conspire mission of signals in opposite directions over with the 'current'ot'static charge of the other the same line, commonly known as a duplex .to form. what may be considercdan augmented telegraph. -I have selectedi'or that purpose 4ocurrent of static charg the well-known system or method of Maren, in

- 7 Eachreversal of the battery will be attend which the receiving-instrument is placed in a ed with such an enlarged current ofstatic bridge-Wire, between the main and artificial charge opposite in polarity to the preceding lines, a method which admits of being conno one; but,'notwithstanding the fact that such veniently compensated for the disturbing efsuccessivecurrents are of opposite polarity, fects of the currents of charge and discharge false signal smay beprevent'ed equally well in in long lines, and which does not require a both cases, from the fact that a current ofcorspecially constructed reecivinginstrument, responding polarity in each instance is flowing any. ordinary apparatus, whether electro iuag- 1 15 over theartificial linefand however-the potennetlc or chemical, being equally well adapted tial ofthe' main lineal: the bridge maybe vathereto. I prefer, however, to make use of a xied during thesimultaneous'static charge and different transmitting apparatus from that de- -'disc halgfl the potential of the artificial line at vised by Maron'in thatalternate positive and --;1h'e otherQextremity-ofthe bridge may be cornegative currents are-employed instead of mo respondingly changed to assimilate the two currents exclusively of one polarity. ;If, however, the'battery-poles were not re- In the accompanying drawings, Figure 1 is @versed to line, but the line were placed from a. theoretical diagram, ilustrating the applicaonc battery-pole to earth, and vice versa, and tion ofmy improved method to a duplex tele no current oflike polarity were flowing in the graph; and Fig. 2 represents certaindetails of artificial line at the instantof static'discharge the apparatus,employed in carrying out the itisobvions that the potentials at the oppoinvention; j site ends of the bridge could not be assimilat- 'Referring to 1., T represents a trans ed, and false signals would therefore 'be pro- Knitter, consisting a lever, 23, provided at duced. one end with an armature, which. is acted upon 1 o .The method for effecting an equality of poby an electromagnet in, a local battery 6, and tential at both ends of'the bridge. consists in a transmitting-key, K, the arrangcmentand diminishing the normal resistance of the artioperation ofall which are well understood, and

tl'iercibre need not be particularly described.

eEs'r AVAlLABLE COP Upon the armature t of the transmitter T are fmounted two insulated contact-arms, n n.

, When the opposite arm of the transmitter is depressed by the action of key K and electromagnet mthe armsn n are raised and lift the contact-levers N N from the respective contact-stops 0', upon which they normally rest, thereby simultaneously forming an electric connection between N and n, and also between tion ot'rest, with the key K open, the path of the current is .from the earth at G by way of 1 and 2 to the point 0'} thence through the contact-lever N and wire 3 to the negative pole of the battery E; thence from the-positive pole ofthe battery by wire 4, contact-lever N, point 0, and wire 5 to the point 6, where the =maiu and artificial lines separate, the main line going through the rheosta't A to the point 7, and thence by the line-wire L to the distant station. The artificial line diverging t'romthe point 6 passes by the rheostat B to the point 8, thence to the point 9. through rheostats C and D to the point 1, where -it connects with the earth or the opposite pole of the battery.

It is obvious thatif the amount oi'resistance in rheostats U and D is made exactly equal'to that of the line-wire L leading to the distant station, the main and artificial lines having each the same capacity for receiving a static charge, no currentwill pass through the. bridgewire 7 and 8 which is connected from the main to the artificial, line, and in which is placed the home receiving-instrument R, provided, however,that resistances Aand B are equal. Moi eover, according to the well-known laws ofelectrieal action, the result will be the same ifthc proportion of the rheostat A to the line L is the same as that of the rheostat B to the resistances O and D taken together in the artificial. line. Withsnch a proportion of resistance, and an equality of capacity for storing static charge, the points 7 and 5:? would at all times be of equal electrical potential upon connecting to or disconnecting eit pole of battery E from line. It is well asc .nned, however, thatthcartificial line, consisting ofa conductor having great resistance and iittie metallic surface, between which and the earti'i inductive reaction can occur, has little or capacity for receiving a. static charge. The main line, on the contrary, has a large static capacity, and when the pole of a battery is connected thereto the battery, in respect to the main line, is as upon short circuit-that is, the current from -either pole of the battery E, after flowing through resistance A, will be absorbed at one point after another along the main line as the line receives its static charge. Thus after connecting the battery E to the main line the point 7, before the line has received its static charge thereat, will be at an electrical potential of zero, while at the same time the potential at point 8 in the artificial line will have nearly attained itsniaximum potential, and therefore a current will flow from the point of higher potential, 8, toward the point of lower potential, 7; but as the main line will almostins-frantly receive its satic charge throughout its wiiole length, the electrical potential at 7 will speedily rise to a maximum equal to the electrical pea, tential of 8, when a current will ceasetoilo cj, 1 v

through the bridge.

. When the apparatus is at rest,'la shei'einbefore described, a current of dcte i iilfl v polarity (in this case a positive current).floivsconf tinuously to line, and a signal is prodncedat. .j I a distant station by depressingthe key Kgi'vhich operates the transmitter and reverses the polarity of battery E without breaking its circuit;

but at the momentof this reversal the line L, be-

ing charged with positive electricity,which has a strong affinity for the negative current which succeeds it, or, in other words, owing to the positive electricity already stored in theline in respect i'o'the succeeding negative charge, the

point 7 has a very low electrical potential, and consequently the initial negative charge tends to flow almost wholly toward the line L, notonly through the resistance A, but also from point 6 through resistance B to point 8, and thence 1 through the receiving-instrument R. Such, current of charge due to the negative pole of the battery is a resultant current consisting,

in the first place, of the static discharge accompanying the disconnection of the main line from the positive pole of the battery, and, seccndly, of the current of static charge from the negative pole. The current ofstatic discharge from the positive poleis in the same direction as the current of static charge from the negajj tive pole, and both conspire to make what may be considered as an augmented current of static charge.

In order to obviate this (lif ficulty, I prefer to construct the artificial line]. 7

in two sections, which sections are composed of separate adjustable rheostats U and 1). if provide also anauxiliary circuit forming a" shunt around the rheostat G, which consists of a wire, 18, leading from the point 9, and a wire, 1st, from thepoint 10, which wires 'arc connected to a circuit-closing device operated by the transmitter T; The transmitter acts to momentarily close said auxiliary or shunt-circuit at the instant of the reversal of the currcnt in the main or artificiallines; and wh ether from positive to negative or from negative to positive, it is obvious that inasmuch asthe rheostats U and D, which constitute the arti ficiai line, may be temporarily'withdrawnand its total resistance reduced, the electrical p tential at point 8 may be momentarily reduced 5 to approximately correspond with the} tential at point 7 at and. during the i the line is receiving its charge.

The device by which the shunt is closed at y the proper time will now be described.

Referring to Fig. 2, H is'" a metallic frame.

which is fixed in a position directly above the BEST AVAILABLE COP upright armt of the transmitter, as best seen in Fig. 1. Within this frame slides loosely a metallic shuttle, I, upon which rests, with slight pressure, a frictionspring, s. Theshuttle I is capable of a horizohtal movement to and fro within the frame H, which motion is limited in each direction by adjustable screwstops' h and h. 'Adjustable contact-pom ts j and j are mounted upon two arms projecting downward from the horizontal portion of the shuttle I and corresponding contact-points are placed upon the upright vibratingarm t of the transmitter T. The contact-points and. stops hereinbefore referred to are so adjusted that the play of the shuttle I is somewhat greater than that of the arm t of the transmitter. The eflect of this arrangement is that the movement of the arm t in each direction momentarily closesthe circuit between itself and the shuttle I, which latter is in electrical connection with the frame H, and consequently with the wire-13. Thus, for example, in Fig. 2, if the arm t move to the right in the direction indicated by the arrow, it will strike against the contact-point j and make electrical contact, after which the shuttle will move along still in contact with the arm until the end of necessary limits.

arm t has completed its stroke, when, the stroke of shuttle I being greater than that of arm t, the inertia of the shuttle will carry it forward still farther in the same direction until it brings up against the stop h; but since arm t is arrested before shuttle l strikes the stop h, electric contact between wires 13 and 14 will be broken. The same action and the same eEect are repeated in connection with thereturn movement of the arm.

It is obvious that by properly adjusting the stops h h and the contact-pointsjj the duration of the contact can be adjusted within-the The stops h h and contactpoiuts j j are relatively so adjusted that at the instant the pole-changing transmitter removes one battery-pole from line and connects another thereto the arm t will simultaneously come incontact with eitherj orj, the contact between t andj orj must continue during the greater portion of the time that the line is rem-ix ing the charge. When the line has received its static charge, or agreater portion thereof, and the electrical potential'of point 7 has attained its maximum amount connection between t'andj or j must be broken." In order to increase the inertia of the shuttle, I prefer to mount suitable weights, 2 and 'i, upon its extremities.

The galvanometer F, which may be thrown into the circuit of the bridge-wire by withdrawing a metallic plug from the commutator f, serves to indicate when'the proper balance has been obtained, or, in other words, when the resistance in rheostat C is sufficient to cause a proper variation of potential at point 8 to compensate for-the change of potential at point 7. p

I do not desire to confine myself to the particu'lar construction of duplex apparatuswhich I have shown and described, as many modifiresnlts may be effected without departing from the spirit of my invention. For example, two separate batteries. of opposite polarities, or even a single one withan ordinary circuit-preserving transmitter,may be employed. In the latter case, however, it would only he necessary to'use one-half of the shunt-circuit-closin g attachment to the transmitter which is represented in Fig. 2 of the drawings.

, I claim as my invention 1. The method, substantially as hereinbei'ore set forth, of counterbalancing the effects of the current of charge in a duplex telegraph system which consists in momentarily diminishing the normal resistance in the artificial line simultaneously with the act of charging the main. line.

'2. The combination, substantially as hereinbefore setv forth, of a main line, an artificial line, and a key or transmitter provided with two sets of circuit-closers arranged to act simultaneously and including means, respectively, one to connect the battery with the main and artificial lines, and the other to temporarily close a normally-open "shunt arounda portion of the resistance in the artificial line.

3. The combination, substantially as hereinbefore' set' forth; of a rheostat normally constituting a portion of the artificial line, a normally-open shunt-circuit passing around said rheostat, and a circuit-closer for completing said sh nut-circuit, which is attached to or op-v erated simultaneously with the leverof the transmitter. I

4. The combination, substantially as hereinbefore set forth, of the transmitter-arm, the reciprocating weighted shuttle moving with slight friction between adjustable stops, and by its inertia having a greater range of vibracations may be employed by which the same tion than the transmitter-arm, and thecon tact-points upon the said shuttle facing the transmitter-arm. 5. The combination ofa main line, the artificia-l line, abridge connecting the main and artificial lines, a receiving-instrument placed in said bridge, a reversible main-line battery, a normally-open auxiliary circuit" or branch, and a key or transmit-ting device provided with two independent sets of circuit-closers, one to reverse the main-line'battery both on an up and down movement of the key, and the other to temporarily close said auxiliary circuit at the instant of each reversal of the bat tery, for the purpose of establishing an equality of potential at both ends of said bridge at and for an instant following each reversal of battery.

6. A key or transmitter provided with a main-line battery pole-changer and an independent circuit-closer for temporarily closing an auxiliary circuit atthe instant of reversing the main-line battery both upon the to-and-fro movement of thetransmitter, and means for tificial line, ficial lines,

retaining said anxilliary circuit closed, in the first instance upon connecting a battery-pole to line, and in the second instance upon disconnecting the same battery-pole from line.

7. In a telegraph-system for simultaneous transmission in opposite directions, the combination, at each station, of a main 1ine,an ara bridge joining the main and artia transmitting-key, and a normal-. ly-open auxiliary circuit which is temporarily closed by the key both upon the to-and-fro movement of said key during an instant after connecting a'batte'ry-pole to line, and again for an instant after disconnecting the same battery-pole from line, of potential at the opposite ends of said bridge at each reversal of the battery.

8. A transmitter or key provided with a main-battery-circnitcloser and anindependent-r circuit closer arranged to temporarily close an auxiliary circuit at the instant of connecting a main-battery pole to line, and means to continne such connection only for an instant, and

to establish an equality mitter, and means: whereby the auxiliary circuit is again momentarily closed and then broken during the period of static discharge upon the return or upward movement of the transmitter.

In testimony whereof I'have hereunto subscribed my name this 8th day of April, A. D. 1882. I

enonens nunrnnvinnn.

Witnesses:

W B. VANSIZE, WM. ARNQUX.

upon the downward movement of the trans-

Images