US697993A - Telephone-exchange system. - Google Patents

Description

No. 697,993. Patented Apr. 22, |902.

W. M. DAVIS.

TELEPHONE -EXCHANGE SYSTEM.

(Application filed Aug. 16, 1901.)

(No Model.)

"WILLIAM M. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR CARLSON TELEPHONE MANUFAC TO TI-IE STROMBERG- TURING COMPANY, OF CHICAGO, ILLI- NOIS, A CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

SECIFICATON forming part of Letters Patent No. 697,993, dated April 22, 1902. `Application tiled August 16, 1901. Serial No. 72,256. (No model.)

To all whom, t may concern:

Be it known that I, WILLIAM M. DAVIS, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Systems, (Case No. 22,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying Io drawings, forminga part of this specification.

My invention relates to telephone-exchange systems, and has for its object the provision of improved means for supplying the operator with supervisory signals, each signal corresponding to a connected subscriber.

Heretofore it has been proposed to employ supervisory signals each associated with a telephone-line and so arranged in each cordcircuit in combination with a condenser that 2c the apparatus at each of the two connected subscribers7 stations is adapted to effect the control of the corresponding supervisory relay or signal, each signal serving accurately to indicate the condition of the corresponding line independently of any other apparatus than the apparatus at the corresponding substation, the two signals thus associated with each cord-circuit indicating to the operator the exact conditions of the respective lines, so that the operator may make no false moves and will not prematurely disconnect connected lines. There are many objections to this form of supervisory signaling apparatus, among which may be mentioned the disagreeable clicking manifested in the receiver of the calling subscriber upon the discharge of the condenser occurring when the called subscriber removes his telephone.

I also aim to accomplish by means of my invention the avoidance of the objection arising upon the connection of long lines with short lines, which where double supervision is employed may in some systems create a shunt relation between the subscriberslines, the short line constituting a shunt of low resistance, preventing the effective operation of the supervisory signals.

I avoid both of the objections above pointed out by including the supervisory signals directly in the sides of the circuit including the telephone-lines, bridge a source of current across the circuit, the bridge being located 'between the supervisory signals, and provide individual shunts about each supervisory-signal magnet, each shunt containing a condenser. Themagnetsofthesurpervisorysignals are preferably wound sufficiently high to avoid the difficulty that heretofore arose upon the connection of long and short telephonelines,while the provision of separate condensers avoids the objectionable click in the calling-subscribers ear.

I will explain my invention more fully by reference to the accompanying drawing, illustrating the preferred embodiment thereof as applied to a single switchboard, though the invention is readily adaptable to telephoneexchange systems of other types.

I have shown well-known telephone substation apparatus at substations 90 and 120, at each of which is a transmitter a, a primary Winding Z), a callbell c, and a telephone switch-hook d, adapted to complete the bellcircuit or the telephone-circuit under the influence of the receiver e. Each telephoneline extends by its limbs to the exchange, each line in this instance being connected with a spring-jack j'. The limbs of the telephone-lines terminate at the common battery g, which is preferably in parallel with the lines, one of the limbs of each line passing through the separable contacts of the springjacks and the operating-magnet 71l of the lineindicator.

I do not wish to be limited to the character of the line-indicator, as any line-indicator maybe employed Without departing from the spirit of my present invention. I have indicatedsmall incandescent lamps h', however, to act in this capacity.

The cord-circuit comprises an answeringplugz' and a connecting-plug 7c, united by tip and sleeve strands, with which are connected the springs of a listening-key Z and a ringingkey m for including the operators telephone set Z in bridge with the telephone-lines and for connecting the calling-generator m in circuit with the bell at the called-subscribers station. One terminal of the common battery g is permanently connected with these sides of the telephone-lines that are in this instance connected with the tip line-springs of the spring-jacks. The other terminal of the common battery is connected with the remainingside of the telephone-lines through the line-indicators when the spring-jacks are free of plugs and is also connected at a point between the magnets n and o with a strand of the cord-circuit-in this instance the sleevestrand that unites the long line-springs of the spring-jacks when subscribers are connected for conversation-the helices of these magnets being thus included in series in the sleevestrand, one upon eachl side of the bridge connection including the battery. The batteryv bridge connection also includes an impedancecoil n2 to prevent the shunting of voice-currents across this bridge. The magnets n and 0 may serve to control the supervisory signals in any preferred manner. I prefer to have these magnets control the supervisory signals electrically, for which purpose I preferably use supervisory indicating-lamps 'n' o as the supervisory signals whose circuits are controlled by the armatures of the magnets or relays fn and o. There are thus established when a connection is put up between subscribers two circuits in multiple connection, the bridge including a battery and impedance being common to these two circuits. In order to prevent one circuit from acting as a shunt of low resistance to the other, the supervisory relays or electromagnets n and o are each made of sufficiently high resistance, one hundred ohms being usually suficient for each electromagnet.

The supervisory magnets n and 0 are shunted by means of condensersp and q, each magnet having its own shunt-circuit, terminating directly at the terminals thereof, so that the condenser corresponding to the calling-subscribers telephone-line will not be discharged upon the removalof the receiver at the calledsubscribers station. The windings of the supervisory relays are such as preferably to be of low impedance, so that the voice-currents may pass through these windings and through the condensers in parallel, so that if the condensers were in effect not present or were disconnected conversation could still be carried on, though obviously this arrange; ment is not so satisfactory.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the ltelephone-lines when connected in shunt-circuit relation, two supervisory signals, each of said telephone-circuits including the operating-magnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet,and a source of current in circuit with the said bridge, substantially as described.

2. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shunt-circuit relation, two supervisory signals, each of said telephone-circuits including the operatingmagnet of a supervisory signal, a condenser in shunt of each supervisory magnet, and a source of' current in the said bridge, substantially as described. v

3. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shunt-circuit relation, two supervisory signals, each of said telephone-circuits including the operatingmagnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet, and a source of current in circuit with the said bridge, the said electromagnets being included in the same side of the combined circuit, substantially as described.

4. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shunt-circuit relation, two supervisory signals, each of said telephone-circuits including the operatingmagnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet,

and a source of current in the said. bridge, the said electromagnets being included in the same side of the combined circuit, substanL tially as described.

5. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-'connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shunt-V circuit relation, two supervisory signals, each of said telephone-circuits including the operating-magnet of a supervisory signal, a con-v denser directly in shunt of each supervisory magnet, a source of current in circuit with the said bridge, and an impedance in the said bridge, substantially as described.

6. In a telephone system, the combination with telephonelines extending from substa= tions to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shuntcircuit relation, two supervisory signals, each of said telephone-circuits including the operating-magnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet, a source of current in the said bridge, and an impedance in the said bridge, substantially as described.

7. In a telephone system, the combination IIO with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shuntcircuit relation, two supervisory signals, each of said telephone-circuits including the operating-magnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet, a source of current in circuit with the said bridge, the said electromagnets being included in the same side of the combined circuit, and an impedance in the said bridge, substantially as described.

8. In a telephone system, the combination with telephone-lines extending from substations to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, a bridge placing the telephone-lines when connected in shuntcircuit relation, two supervisory signals, each of said telephone-circuits including the operating-magnet of a supervisory signal, a condenser directly in shunt of each supervisory magnet, a source of current in the said bridge, the said electromagnets being included in the same side of the combined circuit, and an impedance in the saidk bridge, substantially as described.

9. Cord-connectiug apparatus, comprising the two strands of a cord-circuit, a bridge, two supervisory relays, one included 'on each side of said bridge, and a condenser directly in shunt of each relaywinding, substantially as described.

In witness whereof I hereunto subscribe lmy name this 12th day of August, A. D. 1901.

WILLIAM M. DAVIS.

Witnesses:

FLORENCE WICK'LIN, GEORGE L. CRAGG.

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