US741713A - Circuits and apparatus for telephone-switchboards. - Google Patents

Description

No. 741,713. PATENTED 001.20, 1903,.

. l s.,1s. PRBNTIss. Y

GIRGUITSAND AlPARATUs FOR TELEPHONE SWITGHBOARDS.

APPLIOATION FILED MAY 18,r 1901 N0 MODEL.

1lllllll l l Tn: uonms vivies co. uovo-uma. wumurou. n. c,

rte. 741,713.

UNITED STATESA 'Patented october 2o, 1905i.y

PATENT OFFICE.

CiRCUlTS AND APPARATUS FOR TELEPHONE-SWITCHBOARDS;

SPECIFICATION forming part vof Letters Patent Nol 741,713, dated october 2o, 1903,

. Application filed May 18, 1901l .To all whom it may concern.-

Be it knownthat, SPENCER B. PRENTIss, at citizen of the United States, residing at Washington, in the District of Columbia, have in-` vented a new and useful Im rovement in Circuits and Apparatus for elephone-Switch-i boards, of which the following is a specification.

My invention relates to improvements inl circuits and apparatus for telephone-switchboards, and more particularly to that portion thereof by means of which electrical connection may be eected between the various lineterminals upon the board.

According to the practice now generally followed it is customary to provide connectingplugs adapted to engage a spring or springs constituting a so-called spi-img zf-jack,v in which a subscribers line or a trunk-line terminates. These plugs are usually arranged in pairs, which are connected by flexible conductors, and in the circuit thus formed are usually arranged two `switches or keys, one to enable the operator to connect her telephone into the circuit and the other to enable her to connect in a generator for the purpose of signaling a subscriber into whose line-jack one of the plugs has been inserted. The pairs of plugs are arranged along the front of the switchboard, and there should bea sufficient number of them to serve the jacks upon the section of the board where they are located at the busiest time of the day. For this reason it is necessary to place the pairs very close together, and the switches orkeys above referred to are usually placed just in front of the plugs with which they are designed to cooperate. These switches or keys, hereinafter termed, respectively, the listening and the ringing keys, necessitate a multiplicity of spring-contacts, by means of which p the various circuit changes may be effected, and in their cramped position it is difficult to make the necessary wire connections with the springs, these connections when made forming a crowded mass of wires and soldered joints which are easily deranged and when out of order are diicult to repair; In the case of the ringing-key contactsmust be provided whereby the generator-current may be A sent iu either direction, and at the same time the circuit in the opposite direction is opened,

Serial No. 60,899. (No model.)

' necessitating the multiplication of contactsprings, while in the case of the listening-key less or fewer contacts are necessary.

One of the objects of my invention is to greatly relieve this congestion of wiring and multiplicity of contacts by providing means which enable me to dispense with the usual ringing-keys and their appurtenances upon the front of the board.

A further object is to diminish the number 0f movements of the operator in making a connection, and thereby increase the efficiency of each operator.

A further object is to greatly simplify the wiring of the switchboard and to so arrange the ringing-keys that they will be easily accessible for purposes of repair without interfering with or injuring adjacent connections, thereby reducing the original cost of installation and the cost of maintenance.

A furtherjobject is to provide a simple,

durable, and efficient connecting-plug for telephone-switchboards which shall, besides serving its usual purposes, perform the functions of a ringing-key.

With theseA objects in View the invention consists in providing a connecting-circuit for electrical signaling-lines comprising a pair of conductors and a third conductor and a source of signaling-current connected to the third conductor and to one conductorof the au'. l pf It consists, further, in providing a connecting-plug for electrical switchboards having a tip and a sleeve contact, spring-contacts movably mounted upon the plug and adapted to engage alternately one of said contacts, and a suitable inclosing shell for the parts.

It consists, further, in the novel arrangement of circuits of a telephone-switchboard and the construction and arrangement of parts of a telephone-switchboard connectingplug hereinafter to be fully described and claimed.

My invention is illustrated in the accompanying drawings, in which like reference characters indicate corresponding parts, and in which Figure l is a diagrammatic representation of a portion of a telephone-switchboard to which my invention is applied, two subscribers line-jacks and the stations to which they ICO are connected being shown and the Various signals being entirely omitted from the board. Fig. 2 is an enlarged detail View, in central sectional elevation, of a preferred form of connecting-plug embodying the essential features of my invention. Fig. 3 is a detail.

Referring to the drawings, X and Y are two subscribers stations connected by line- wires l 2 and 3 4, respectively, with jacks J and J' upon the switchboard at central office, each jack consisting of the usual spring and ring contacts j' 12. The usual instruments and circuit connections at the subscribers sta tions are shown in diagram, comprising at station X a transmitter T, battery B, induction-coil l, receiver R, hook-lever H, generator g, and ringer Z7. Similarly at station Y are shown transmitter T', battery B', induction-coil I', receiver R', hook-lever H', generator g', and ringer Z2'. At subscribers station X, hereinafterdesignated the calling subscriber, the receiver Ris shown removed from the hook and the lever H as in its raised position under the influence of its spring (not shown) to cut out the generator and ringer and close thelocal transmitter-circuit and also to connect the receiver and the secondaryof theinducti'on-coil to line. At station Y, hereinafter designated the called subscriber, the receiver is shown upon t-he hook and the lever H' down to connect the ringer to line.l

In Fig. l a pair of connecting-plugs P P' are shown with their outer casings removed and inserted into line-jacks J J', respectively, these plugs being connected by the usual cord-circuit conductors 5 6, these conductors making connection between the sleeves and the tips of the plugs in a manner to be hereinat'ter more fully described. The centralofiice operators telephone, set is shown in diagram at O, the induction-coil, switch-hook, and contacts being omitted and the transmitter being shown on a closed circuit for the sake of clearness. This set is arranged to be bridged across the cord-circuit by means of the listeningkey L, consisting of springs ZZ', contacts Z2 t, plunger Z4, and operating-lever Z5, pivoted at l, all of Well-- known construction. This portion of the circuits and apparatus being old and forming no part of the present invention may be varied in construction at pleasure Without departing from the invention.

The calling or generator circuit and the means for connecting the same with the lines which constitute the present invention will now be explained in brief. One form of plug suitable for making the connections will then be described in detail and the operation of the circuits and apparatus as a whole will then be described.

An additional conductor 7 is added to the cord connecting the plugs P and P', and at any suitable point a generator G is bridged across this conductor and one of the voicecurrent conductors, as 6. The plugs are of special construction, being provided with movable contacts by means of which the voicecurrent circuit may be broken and the generator-circuit connected to line. The contacts for making these circuit changes are shifted by subjecting the plugs to added pressure after they have been inserted into the line-jacks, as will bev more fully explained presently. Normally the parts of the plug are in the position shown at P, Fig. l, and in Fig. 2 as a whole, in which the conductor 5 is connected to spring s', `the latter being in contact with sleeve 192 of the plufr. Conductor 6 is in permanent connection with the tip 19' of the plug. The third or generator conductor 7 is connected to spring s2, the free end of which is normally out of contact with the sleeve 192. Both the springs s' and s2 are so mounted that, the plug beinginserted into the jack, when extra pressure is applied the parts take the position shown at P', Fig. lthat is, spring s' is forced out of engagement with sleeve 1)?, thus interrupting the talkingcircuit, and spring S2 engages said sleeve, completing the generator-circuit- Referring now more particularly to Fig. 2, A represents the shell or casing of the plug inclosing the working parts. 19' is the tiprod, of brass, bronze, or other suitable metal, forming the base of the strnctu re, upon which is secured in any suitable manner the sleeve 192, also of metal, the two being separated by a tube of insulation z'. The sleeve 192 is provided With a flange 193 at its inner end, against which abuts the block of insulating material t". Slidingly mounted upon the tip-rod is a metallic sleeve 1?", having at its rear end a flange 1f. This sleeve may be split a portion of its length from the end opposite the flange,

Aas shown in Fig. 3, in order to make a better contact with the rcd, the spring portions taking up the wear. The sleeve 19" carries a second sleeve or boss 112, of insulting material, to which it is firmly secured, and upon this second sleeve are mounted the contact-springs s' s2, to which are secured the circuit-wires 5 and '7. The rearwardly-projecting portion of the sleeve t? is provided with a chamber or recess to admit the nut 11G, the latter being adapted to engage external threads upon the rod 19' and limit the rearward movement of the sleeve 19I and sleeve t2. Between the insulating-block t' and the sleeve i2 is fitted a coiled spring S, which may be secured at one end to the tip-rod19' and at the other to the sleeve 1)', thus to make more perfect electrical connection between these parts and maintain the sleevespand f2in theirextreme rearward position. The contact-springs s' s2, mounted in any suitable manner upon the insulating-sleeve t2, project toward the forward end of the plug, the former, being normally in contact and making electrical connection with the flange 193 of the plugfsleeve192. This spring s' is provided With a bend or projection sm, extending inwardly in such a manner as to be normally free of, but adapted to ride upon, the block t" IOO IIO

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when the sleeve t2 is forced Vforward against the action of the spring S, therebyto take the lthrust of the spring s and lift its contact end out of engagement with the flange p3. The spring 32 is similarly mounted, preferably, on the opposite side of the sleeve 2, this spring being shorter than spring s and normally supported by a bend or projection S20, which rests upon block c", its free end being adapted to make contact with flange p3 when sufficient pressure is applied to` the plug. A block or flange 3, preferably of insulating material, is rigidly secured to the plug by any suitable means, such as a pin, (not shown,') with which block the plug-casing makes a sliding contact and closure. The rear end of the casing is provided with a central aperture to admit the circuit- wires 5, 6, and '7, which pass therethrough and are secured, respectively, to springs s', terminal piece p7, which is in contact with sleeve p4, and spring s2, the rear end of the casing resting against and being secured to the sleeved? y The operation ofthe device and circuits thus described is as follows: Supposing that the subscriber at station X wishes to communicate with another subscriber, as Y, he signals central in any suitable or well-known manner. Thereupon the .operator at central inserts an answering-plug P into the jack J, forming the terminal of that line. The spring S of the plug is of such strength that it will not yield to the ordinary pressure necessary to force the plug into the jack-seat, so that the contact-springs s s2 of the plug P remain in the normal position-that shown-whereby the calling-subscribers line is connected with conductors 5 5. The operator then manipulates the listening-key L in the usual manner and having ascertained the number wanted Vreleases said key and inserts the calling-plug P in the jack J', (or into thejack of atrunkline leading to the section of the board upon which the jack of the wanted subscriber is located,) bringing sufficient additional pressure to bear upon the plug to 'overcome the resilience of spring S and move contactspring s out of engagement with lange p3 and spring s2 into contact therewith, thereby breaking the electrical connection of conductor 5 with said flange and connecting conductor 7 therewith. Current from the generator G (said generator being operated by power or bythe free hand of the operator) now flows out to the called station over the following circuit: from generator G by wire 7 to spring s2 of plug P, flangeps and sleevep2 to ring'j2 of jack J', line-wire 3 to ringer h' and lever H' at station Y, wire 4, jack-sprlngj', plug-tip p', and return to generator by wire 6. Having thus given the call, the operator re leases the plug-handle, when the parts immediately resume their normal position under action of spring S, as shown in plugP and in Fig. 2. If the called subscriberfails to answer, the operator repeats the call. When the called subscriber answers, shouldl the calling sub-' scriber have left his phone all that is necessary to' recall him is for the operator to press his plug to its extreme inward position to connect the generator, thereby ringing back. It will thus be seen that by constructing both plugs of each pair similarly I am enabled to dispense with the two ringing-keys now usually employed, mounted upon the front of the switchboard, together with their attendant complications of circuit connections and conother from a supply kept on hand for the pur? pose, and send it to the factory for repairs. The annoyance so well known to manufacturers of having to send an expert out to a switchboard which they have installed to overhaul the circuits is thus avoided in all cases where the trouble is inthe ringing device.

Although I have described specifically one form of plug embodying my invention jas hav? ing the contact-springs engage the sleeve-contact of the plug, this is by no means essential, as these springs may be arranged diiferently, and many other changes in details of construction and arrangement of parts may be made without departing from the spirit of the invention, and these I wish it to be un- Y stood fall strictly withinthe scope and purview of the same.

Having described my invention, what I claim as new, and'desire to secure by Letters Patent of the United States, ilsl. Connecting means for terminals of electrical signaling-lines comprising a pair of conductors Vand a third conductor, a source of signaling-current permanently connected to the third conductor and to one conductor of the pair, and switching mechanism at the ends of said conductors cooperating with terminal contacts carried by said switching mechanism, substantially as described.

2. In an electrical switchboard,lineterminals suitably placed thereon, connecting means comprising a pair of conductors and a third conductor, a source of sign aling-current permanently connected to the third conductor and to one conductor of the pair, and switching mechanism at the ends of said conductors cooperating with terminal contacts for connection with said line-terminals, substantially as described.

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connected to the third conductor and to one conductor of the pair, and switching mechanism at the ends of said conductors coperating with terminal contacts carried by said switching mechanism for connection with said line-terminals, substantially as described.

4. In an` electrical switchboard, lineterminals suitably placed thereon, means for connecting said line-terminals comprising a pair of conductors and a third conductor, a source of signaling-current permanently connected to the third conductor and to one conductor of the pair, terminal contacts for connection with said line terminals, and switching mechanism at the ends of said conductors cooperating with said terminal contacts for connecting alternately (a) said pair of conductors, and (ZJ) one conductor of the pair and said third conductor, to a line-terminal, substantially as described.

5. In a telephone-switchboard, spring-jacks forming line terminals suitably mounted thereon, a connecting-circuit comprising a pair of conductors and a third conductor, a source of signaling-current connected to the third conductor and to one conductor of the pair, plugs carrying terminals for engagement with said spring-jacks, said plugs being provided With contacts movable relatively to said plug-terminals and so arranged as to be adapted to connect to line alternately (a) said pairofconductors, and (b) one of said pair and the third conductor, substantially as described.

6. A connecting-plug for telephone-switchboards comprising a tip and a sleeve contact, spring-contacts movably mounted upon the plug and adapted to engage alternately one of said contacts, and a suitable inclosing shell for the parts, substantially as described.

7. A connecting-plug for telephone-switchboards comprising a tip and a sleeve contact,

movable springs slidingly mounted thereon and adapted to engage one of said contacts, means for making continuous electrical connection with the other of said contacts, and means for maintaining the parts normally in one position, substantially as described.

8. A connecting-plug for telephone-switchboards comprising a central rod forming the tip-contact, a sleeve-contact insulated therefrom, a conducting-sleeve slidingly mounted upon said rod and carrying a block of insulation, contact-springs secured to said block of insulation and extending into proximity to the sleeve-contact, a spring adapted m maintain normally the block of insulation in such a position that one of said contactsprings will be in engagement with the sleevecontact, the parts being so arranged that when pressure is applied to the casing the last-named contact-spring Will be moved out of engagement with the sleeve-contact and the remaining spring-contact Will be moved into engagement therewith, substantially as described.

9. A connecting-plug for telephone-switchboards comprising a tip and a sleeve contact, springs slidingly mounted thereon and adapted to engage one of said contacts, one of said springs having a bend or shoulder to engage a portion of the plug structure and having a contact portion to engage one of said plugcontacts, means for maintaining the parts normally in one position, and suitable electrical connections, substantially as described.

10. A connecting plug for telephoneswitchboards comprising a tip and a sleeve contact, springs slidingly mounted thereon and adapted to engage one of said contacts, a sleeve or block adjacent said contact to be engaged and through which current cannot pass to said contact, a bend or shoulder upon one of said springs to engage said sleeve or block, means for making continuous electrical connection with one of said contacts, and means for maintaining the parts normally in one position, substantially as described.

In testimony Whereoic I have signed my name to this specification in the presence of two subscribing Witnesses.

SPENCER B. PRETISS,

Witnesses:

T. BLAIR SHOEMAKER, EMORY H. BOGLEY.

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