US476509A - Keyboard-circuit for multiple switchboards - Google Patents

Description

(No Model.) 2 Sheets-Sheet I.

O. A. BELL. KEYBOARD CIRCUIT FOR MULTIPLE SWITUHBOARDS.

Patented une 7, 1892.

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0. A. BELL. V KEYBOARD CIRCUIT FOR MULTIPLE SWITGHBOARDS,

No. 476,509. Patented June 7, 1892.

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UNITED STATES PATENT Orricn.

ORO A. BELL, OF NEIV YORK, N. Y., ASSIGNOR TO THE \VESTERN ELECTRIC COMPANY, OF ILLINOIS.

KEYBOARD-CIRCUIT FOR MULTIPLE SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 476,509, dated June '7, 1892.

Application filed September 30, 1891. Serial No. 407,261. (No model.)

To aZZ whom it may concern: one side of the block. A connection from the Be it known that I, ORO A. BELL, a citizen tip of the otherplug extends similarlythrough of the United States, residing at New York, the contact of the other calling-key to the in the county of New York and State of New other of the two springs described. The sin- York, have invented a certain new and usegle spring upon the opposite side of the block 55 ful Improvement in Keyboard-Circuits for is connected with the sleeves of both plugs. Multiple Switchboards, (Case No. 3,) of which One terminalof the operators telephone set the following is a full, clear, concise, and exis connected to the contact-anvil of said sinact description, reference being had tothe acgle spring and the other terminal to the con- IO companying drawings, forming a part of this tact-anvil of that spring which is connected 6o specification. to the testing-pin g. The contact-anvils of the My invention relates to keyboard-circuits two springs are connected together through a for multiple switchboards of telephone-excondenser. Thus the springs of my improved changes. Its object is to simplify the circuit key perform all the functions of the usual key connections and the mechanism of the open by simpler means. 65 ators apparatus. My invention will be more readily under- My invention is especially adapted for use stood by reference to the accompanying drawwith a metallic circuit system, and comprises a ings. novel form of listening and calling key and Figure l of the drawings shows an elevation keyboard-circuit connections adapted to the of one side of my improved combination-key. 70

same. Fig. 2 is an elevation of the other side thereof.

Heretofore it has been usual to provide Fig. 3 is a cross-section through the centerof calling-keys and a listening-key having two the listening-key. Fig. 4 is a diagram showsprings with their contact-anvils adapted to ing a multiple-switchhoard system comprisz 5 disconnect both sides of the condenser and ing two multiple switchboards equipped with 75 one terminal of the operators telephone from my improved keyboard apparatus and cirthe circuit, a third spring and its contact-ancuits and two sub-stations connected together vil to disconnect the other terminal of the for conversation. telephone, and a contact-spring adapted to Like parts in the several figures are desigcomplete a direct circuit between the tips of nated by similar letters and figures of refer- So the connecting-plugs. ence.

lVith my improved form of listening-key I will now describe the construction of my and circuit connections I am enabled to disimproved key in greater detail. pense with one spring and its contact-anvil, Referring to the Fig. 1, a is preferably a thereby simplifying the mechanism and the block of insulating material, as hard rubber. 85

circuit. Upon this block are mounted springs b, 0, cl,

The spring and contacts which constitute and 6. These are secured to the block at the calling-keys in my improved key are of their upper ends by suitable means, as by the usual construction and are mounted upon screws. The lower ends of the springs 11, c,

40 ablock of some insulating material. The lisand e are bent inward, so as to rest against 90 tening-key is preferably mounted upon the the inclined surfaces of the wedge-shaped rubsame block, and consists of a single spring ber blocks f g h. The forms of the spring 0 upon one side of the block, with its contactand of the block g are shown in Fig. 3. In anvil and two springs upon the opposite side front of the springs b and e, but insulated 5 of the block, each furnished with a contacttherefrom, are mounted spring-contacts iand 5 anvil and adapted to close together when j. These areso adjusted that whenthe springs they are separated from their contact-anvils. b and c are pressed outward by a movement A connection from the tip of one connectingof the wedges f h the springs are forced into plug extends through the usual contacts of contact with the contact-springs 1' and j, re-

one calling-key to one of the two springs at spectively. In front of the central spring 0, I00

and also insulated from it, is another spring (I, having attached to it a stud 7;, which projects freely through a hole in the spring 0. Spring 0 is furnished with a contact-point Z, which rests upon the spring (Z after the former has been slightly raised, as by thrusting down wedge g. Beneath springs b and e are insulated contact-strips m it, against which the said springs normally rest. Beneath all the springs and normally insulated from all are two contact-strips 0 p. The strip 0 is so shaped that a portion of it lies under the contact k and serves as a contact-anvil when the wedge g is in the position shown. The other strip 12 also has a projection under the spring 0, upon which a contact-point upon thelatter rests when the key is in the position shown. Upon the opposite side of the block a, as shown in Fig. 2, are mounted corresponding springs b c 6', bearing against the oppositelyinclined faces of the wedges f g h, respectively. In front of the springs b eare placed contact-springs 2" 3'', against which the springs I) e are forced when the corresponding wedges are depressed. Beneath the springs upon the surface of the block a are contact-strips 0'19. The spring 0 is provided with contact-points, against which the springs b 6' rest normally. The strip 13 is provided with a contact-point, against which the spring 0 rests when the wedge g is in the position shown. The wedges fg hare secured to,lower ends of plungers moving through holes in the block a, and are thus capable of a limited vertical movement. These plungers may carry upon their upper ends heads, whereby they may be pressed down, or they may be acted upon by the usual cam-lever.

I will now proceed to describe the circuit connections adapted to this form of key, rcferring to circuit diagram, Fig. 4. I will first describe the connections to the substations, however.

In Fig. 4 the normal circuit from a sub-station (station 1, for example) may be traced over its line-wire 0' through the line-spring and contact-anvil of its line-jack r at the first board, thence similarly through line-jack r answering-jack T and annunciator r" at the second board, thence returning by line r to station 1. Line 0' is connected to the frame or test-rings of all the spring-jacks 1'', T and T The operators outfit comprises the two double connecting-plugs u it, the calling and listening key, telephone-set 'v, test-battery w, and clearing-out drop y. Like contacts of the two plugs are connected as usual. hen the operators set is not connectedthatis, when the springs c and (Z are separated from their respective oontact-anvils and are not connected togetherthe circuits are as follows: From tip of plug to to spring 6, anviln, spring 0, spring (Z, anvil in, spring I) to tip of plug to, and from sleeve of plug 16 through spring 6, contact 0 to spring 1), (since the anvils o 0' are in the key upon one strip 0,) thence to sleeve of plug to. Then the plunger of the mason listening-key is not forced down, however, the circuit is, as before, to spring 0, thence through anvilp, condenser :20, anvil 0, contact-stud 7;, spring (Z, and thence to tip of plug 16', as before, and the operators telephone-set i; is placed in a bridge or shunt connection between the sleeves and tips of the plugs thus: from anvil 0 through spring 0', anvil p',telephone-set 'U, anvil 0, thence through condenser 03 to tip of plug it or stud k, and spring d to tip of plug to. The contact-springs t'z" {Llldj 7" are connected to the opposite poles, respectively, of a calling-generator. \Vhen the plunger of either of these keys is depressed, the two springs of the key which are connected to the tip and sleeve of the corresponding pl ugare raised from their anvils and closed upon the poles of the calling-generator. A clearing-out annunciator y of large resistance and self-induction is permanently bridged in between the tips and sleeves of the plugs. To the conductor joining the sleeves of the plugs the usual test-battery w is connected through a retardation-coil, and to complete the testcircuit a connection is extended from the middle of the operators telephone-coil to earth.

I will now trace very briefly the operation of the system shown. The subscriber at, say, station 1 calls in the usual manner. The shutter of annunciator 0' falls, notifying the operator that a connection is desired. The operator thrusts an swering-plu g to into answeringjack 0 of the line for station 1, raises the plunger of her listening-key, and thus through condenser :c loops her telephone into circuit with subscriberat station 1. Havinglearned his ordersay, for a connection with station 2she proceeds to test the jack of that line at her board. If now a connecting-plug is already thrust into anyspring-jack of line 8, then a difference of potential exists between the testrings of the spring-jacks of that line and the earth, due to a test-battery similar to w, connected to the sleeve of the plug, and as the operator applies the tip of that plug to to the test ring of jack 8 a current will traverse spring I), anvil on, spring cl, stud 7c, anvil 0, one-half of operators telephone-coil U, thence to earth, and a click will be producedin the telephone c, which will be recognized by the operator as an indication that the line tested is already in use; but assume that she finds the line to station 1 not in use she then inserts plug it into jack 8 and depresses plunger f of the calling-key at the right, sending a call-signal to station 2. The subscriber having responded, the operator is in communication with both, since her telephone-set is in a bridge connection between the two sides of the circuit joining the two subscribers. Having assured herself that they are in communication, the operator depresses plungergof her listening-key, thereby disconuectin g her telephone o and condenser 00, leaving the two subscribers connected directly, as already traced. When conversation is finished, either subscriber by operating his generator causes the shutter of clearing-out annunciator 'y to fall, thereby notifying the operator that they may be disconnected.

My improved key admits of various modifications, which will readily suggest themselves to those skilled in the art to which the invention pertains. Hence I do not limit myself to the precise form shown.

Having thus fully described my invention, 1 claim as new and desire to secure by Letters Patent 1. As an element in a keyboard-circuit, the combination of contact-anvilsp p, springs c 0, adapted to make contact with p p, re spectively, a spring (1, adapted to come into contact with and be raised by springc when said spring 0 is separated from its anvil p, a contact-anvil 0, adapted to make contact with spring (Z when the said spring is not raised by spring 0, and a wedge and plunger or other suitable means for raising springs c c from their contacts, substantially as and for the purpose described.

2. In combination, contact anvils p p, springs c 0, adapted to rest upon said contacts 1) 1), respectively, a spring (Z, adapted to make contact with and be raised by spring 0 when said spring cis raised,a contact-anvil 0, adapted to make contact with spring cl when said spring is not raised, a condenser a, connected between contact-anvils p and 0, a telephone connected between contacts 0 and p, and suitable means forseparating the springs c c from their respective contacts, substantially in the manner described.

8. In combination, the block a of suitable material, the contact-strips 0, 0', 19,19, m, and a, mounted thereon and adapted to make contact with the springs d, b, and e, c, c, b, and 6, respectively, the springs c and (Zbeing furnished with contact-points, whereby they are crossed together when the spring 0 is raised from its contact-anvil, the contact-springs 2' i" j j, adapted to make contact with the springs b b e 6', respectively, and wedges f g h, attached to plunger-s moving in perforations through the block, substantially as described.

4.. In combination, the block a, contactstrips 0, 0,p, 1), m, and 01, adapted to make contact with springs cl, 5', and e, c, c, b, and 6, respectively, conductors extending from the tip and sleeve of a connecting-plug to the springs e and 6', respectively, other conductors extending from the tip and sleeve of another connecting-plug to spring I) and Z), respectively, a conductor joining strip m with spring (2-, a conductor joining spring 0 with strip n, a telephone having its terminals connected to strips 0 and p, a condenserhaving its sides connected to strips 0 and p, respect- 6o ively, conductors joining springs t and J and connected to one pole of a source of electric current, another conductor joining springs 2 and j and connected to the other pole of the source of current, and an annunciator 111- cluded in a conductor joining the contactstrip 0 with the conductor joining the strip 071 and spring cl, substantially as set forth.

5. The combination, in a listening-key, of a spring connected to one contact-piece. of a connecting-plug, a contact-anvil therefor, connected to one terminal of a telephone and to one side of a condenser, means for forcing said spring away from its contact-anvil, a second spring connected to one contact-piece of another connecting-plug, and a contact-anvil therefor, connected to the other side of the said condenser, said second spring being so disposed with relation to the first spring as to make electrical contact therewith and to be raised from its anvil simultaneously with the separation of the first spring from its anvil, whereby the telephone and condenser are disconnected from the connecting-plugs and the said plugs are connected directly, substantially as described.

6. The combination, with loop-plugs, each having two contact-pieces, of a spring connected to two corresponding contact-pieces of the plugs, contact-anvil thereof, connected to one terminal of a telephone, a second spring connected to one of the remaining contactpieces of the plugs,an anvil therefor, connected to the other terminal of said telephone and to one side of a condenser, athird spring connect- 5 ed to the remaining contact-piece of the plugs,

a contact-anvil therefor, connected tothe other side of said condenser, and means for separatin g all the springs from their contact-anvils and closing said third spring upon said second spring, whereby said condenser normally included between two corresponding contactpieces of said plugs and said telephone normally in a bridge connection between the different contact-pieces of said plugs may be disconnected from the plugs and connection made directly between like contact-pieces of the two plugs, substantially as described.

In witness whereof I hereunto subscribe my name this 21st day of July, A. D. 1891.

0R0 A. BELL. Witnesses:

FRANK R. McBEnrY, JOHN O. PARSONS.

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