US1324364A - Telephone-exchange system - Google Patents

Description

R. S. WILBUR.

TELEPHONE EXCHANGE SYSTEM.-

APPLICATION FILED MAY 13, 1918.

1,324,364. Patented Dec. 9,1919.

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. RAY s. WILBUn, or nrnnnnns r, new JERSEY, assrenoa T0 wnsrnnn nrnc'rnro columns, INCGRPORATED, or new iron-inn. Y.,

A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

asagna;

Application filed May 13, 1918.

To all Mam it mayconcera:

Be it knownthat 1, Key S. VVILBUR, a

citizen of the United States, residing at Lyndhurst, in the county of Bergen, State of New J ersey, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description This invention relates to telephone exchange systems and more particularly to those in which trunk circuits are employed in completing connections between telephone switchboards oroflices.

In such systems it is desirable to provide signaling means wherebythe operators handling the connections are definitely advised as to the answered or unaswered condition of the called telephone station. Especially operator controlled signaling means,it is very desirable that the completing or trunk operator receive an ac to provide an improved system of this character which will be simple and inexpensive and will provide a definite signaling means solely responsive to the answer of the called station and unaflected by changes in the electrical conditions ofthe trunk circuit incident to the establishment of the telephonic connection.

To attain this object, in accordance with a feature otthe'invention, a trunlrcircuit provided with the usual ringing signal controlled by a supervisory relay and adapted to indicate when the called station answers, is associated with means to prevent'a pre mature indication being given by the signaling device due to an incidental momentary operation of the supervisory relay prior to the response of the called-station.

The nature of this invention will more fully appear from the following specification and annexeddrawing in whichthe figure shows diagrammatically a trunk circuit embodying the invention and suflicient portions of a line circuit and of a link circuit for cooperation therewith, to properly illus- 50 trate, the operation of the system.

In the accompanying drawing, a trunk circuit D interconnects the switchboards or offices B and C. terminating-at office B in a plug 5and at ofiice C in a jack 14. An ordinary line circuit A equipped with the usual Specification of Letters Patent.

.. in jack 1 of line operates,

Patented Dec. 9, 1919. Serial No. 234,346.

line relay 3, cutoff relay 2 and line signal 4 terminates in a jack 1 at otfieeB. A connecting or link circuit E of any usual type is provided at otlice C and terminates in a plug 15' for connection with jack 1% of the trunk circuit Dr The portions of the link circuit (not shown), have been omitted since they are unessential to a proper understanding of the invention.

It is thought that. the invention may be more fully (oniprehended from the following description of the operation of the system.

Assuming that the operator at switchboard C desires to call station A on the line terminating in ja k 1 at station E; the operator at B is notified in some suitable manner over a call circuit or otherwise and assigns trunk circuit D. The operator at C thereupon inserts plug 15 of the link circuit E in the jack 14: of the trunk circuit D. The lamp 17 is lighted over a circuit extending from battery through the lamp 17, the resistance 16 and the sleeve contacts of plug 15 and jack 14 to ground. Relay 13 is also operated over acircuit extending from battery through the winding of relay 19, the ring contacts of plug 15 andjack 14, the right-hand winding of relay 13. the tip con tacts of jack 14 and plug 15 to ground. However due to the high resistance of the right-hand winding ofrelay 13'. the superternate contact of relay 13 to ground. Be-

lay 8 is also operated over a circuit established from battery through the resistance 21,-the winding of relay 8 and the alternate contact of relay 13 to ground. The operator at switchboard B thereupon inserts plug 5 A, completing a circuit extending from battery through the winding of relay 9, the sleeve contacts of plug 5 and jack 1 and the winding of cutofl relay 2 to ground. The operation of relay 2 thereupon removes the line relay 3 and its associated line signal 4- from their normal association with the line circuit A. The relay 9 also establishing the continuity of the tip conductor of the trunk circuit, but due to the operation of relay 13 and of relay 8 no further useful function is performed thereby at this time.

The operator at switchboard B then actuates the ringing ey 10 in the usual manner, impressing signaling current upon the V conductors of the line A. to cause the operation of the usual signaling device at the called station. The ringing key released after the signal at the station on the line A has been operated, the trunk circuit apparatus is then in condition to respond to the answer of the called station. Upon the answer of the called station, the supervisory relay 6 is operated over a circuit extending from battery through the winding of relay 6, the lower normal contact of ringing key 10, the ring conductors of plug 5 and jack 1 through the apparatus at the called station, the tip conductors of jack 1 and plug 5, the upper normal contact of ringing key 10, and the upper alternate contact of relay 9 to ground. In operating, relay 6 completes a shunt circuit for relay 8 including the left-hand normal contact of relay 7, the contact of relay 6, and the middle normal contact of relay 7. Due to the presence of this shunt circuit, relay 8 releases, thereby completing a circuit from battery through the lower alternate contact of relay 9, the winding of relay 7, the contact of relay 8, the contact of relay 6, the

middle normal contact of relay 7 and the alternate contact of relay 13 to ground. Relay 7 thereupon operates and by the openin of its right-hand normal contact extingulshes lamp 12. A locking circuit is also established for relay 7 extending from battery through the lower alternate contact of relay 9, the winding and the right-hand al ternate contact of relay 7, the alternate contact of relay 13 to ground; Through the closure of its middle and lefthand alternate contacts, relay 7 also places the left-hand winding of relay 13 in parallel with the right-hand winding thereof in the usual manner, thus reducing the resistance of the circuit including the supervisory relay 19 of the link circuit E. The consequent operation of relay 19 establishes the usual shunt circuit through resistance 18, around the lamp 17, thereby causing the extinguishment of such lamp. The operator at switc 1- board 0 may now converse wlth the station A upon the actuation of the usual listening key 20. Upon the completion of the conversation, the operator at switchboard Cremoves the plug 15 from the jack 14-, thereby restoring the apparatus associated with the link circuit E to its normal condition and releasing relay 13 to cause the display of the disconnect lamp 11 at the switchboard B, over a circuit established from battery through the middle alternate contact of relay 9, the lamp 11, and the normal contact of relay 13 to ground, ZUpon observing the 10 being lighted condition of lamp 11, the operator at switchboard B removes plug 5 from jack 1, thereby restoring all apparatus to normal condition.

During the signaling of the called station, the condenser 22 and the conductors of l the line become charged and upon the release of the ringing key 10, a discharge may take place through the winding of relay 6, causing the momentary operation of such relay. However, the relay 8 is adapted to be unaffected by any incidental momentary establishment of the shunt circuit therearound and will release only upon a shunt circuit of considerable duration. Therefore, the circuit of relay 7 is not completed due to any incidental operation of the relay 6 caused by the discharge of the capacitance of the line A and the ringing signal lamp 12 is not prematurely extinguished thereby.

What is claimed is:

1. In a telephone exchange system, a line circuit having capacitance, a station associated therewith adapted to be called, a trunk circuit for connection therewith, a supervisory relay for the trunk circuit adapted to operate upon the answer of the called station when the trunk circuit is connected with the line circuit, a signal control relay, a relay closing the circuit thereof upon its release, and means operative upon the discharge of the capacitance over the trunk circuit to cause a momentary shortcircuiting of the winding of the lastinentioned relay, said relay being unaffected thereby.

2. In a telephone exchange system, a line circuit, a station associated therewith adapted to be called, a trunk circuit for connection with the line circuit, a supervisory relay for the trunk circuit adapted to operate upon the response of the called station, a signal control relay, a slow-release relay energized prior to the response of a called station adapted to complete an energizing circuit for the signal control relay when released, and means efiective upon any incidental premature operation of the supervisory relay to establish a temporary short circuit around lease relay of insufficient duration to effect the release thereof,

3. In a telephone exchange system, a line circuit, a station associated therewith adapted to be called, a trunk circuit for connec" tion with the line circuit, a relay operating upon the connection of the trunk circuit with the line circuit, another relay operating prior to the response of the called station, a supervisory relay operating upon the response of the called station to release the second mentioned relay by completing a short circuit therearound, and a signal control relay jointly pentrplled by the above mentioned r y 4:. In a telephone exchange system, a line circuit, a station associated therewith adapted to be called, a trunk circuit for connection with theline circuit, a relay operating prior to the response of the called station, a supervisory relay responsive to the answer of the called station to establish a shunt around and thereby release the first mentioned relay, a signal control relay operating upon the release of the first mentioned relay, and a'locking circuit for the signal control relay completed upon the operation thereof.

5, In a telephone exchange system, a line circuit, a station associated therewith adapted to be called, a trunk circuit for connection with the line circuit, a first relay operating upon the connection of the trunk circuit with the line circuit, a second relay operating independently of the connection of the trunk circuit with the line circuit, a signal control relay, an energizing circuit therefor completed upon the contemporaneous energization of the first relay and the release circuit, a signal control relay operating upon the contemporaneous operation of the sleeve relay and the release of the slow-release relay, and a supervisory relay responsive to the answer of called station to establish a short circuit around the slow-release relay of suflicient duration to cause its release.

' In witness whereof, I hereunto subscribe my name this 9th day of May, A. D;, 1918.

RAY s. WILBUR.

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