US2139247A

US2139247A - Telephone system

Info

Publication number: US2139247A
Application number: US26027A
Authority: US
Inventors: Ray L Stokely
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1935-06-11
Filing date: 1935-06-11
Publication date: 1938-12-06
Anticipated expiration: 1955-12-06

Description

Dec. 6, 1938. R L STOKELY 2,139,247

' TELEPHONE SYSTEM 4 Filed June l1, 1935 DIFFERENT/AL RING/Na lm'.

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AT TORNEV Patented Dec. 6, 1938 PATENT QFFECE TELEPHONE SYSTEM Ray L. Stokely, Floral Park, N. Y., assigner to Bell Telephone Laboratories, Incorporated, New YorlnN. Y., a corporation of New York ApplicationJune 11, 1935, Serial No. 26,027

17 Claims.

This invention relates to telephone systems and particularly to dial telephone systems.

-The` object of the invention is theprovis'ion of improved circuit arrangements for use in automatically completing calls to and from lines of highresistance and poor insulation.

This invention is a line circuit arrangement comprising an impulse repeater for a single-wire party line in an` automatic telephone system. According to this invention, circuit means is provided for operatively extending a subscribers line to an individual impulse repeater in response to the origination of a call by the removal of the receiver at a station on the line. The impulse repeater comprises a sensitive impulse relay and circuit Ameans responsive to the opening of the impulsecircuit for disconnecting the winding of the impulse relay from the line to insure release of this relay. ,p

A feature of the invention is the provision of circuit means for delaying the connection of the line to the associated impulse repeater for a predetermined short interval of time so that the calling subscriber may ascertain whether the line is in use before calling another station on vthe same line.

Another feature of the invention is means Vcomprising a ring-up relay, for operation when the subscriber at one station calls another station on the line, to prevent the operative extension o f the line to the associated. impulse repeater.

Another feature of the invention is circuit means for restoring the ringup relay of a line circuit upon completion of a call between two stations on the line, thereby enabling the operative extension of the line to an associated irnpulse repeater upon the subsequent initiation of a call from this line to a station on another line.

Another feature of the invention is circuit means comprising the ring-up relay of a magneto line for operating a' permanent .signal alarm in case the line becomes permanently grounded due to the removal of the receiver at a station on the line or due to a trouble condition.

These and other features of the invention will be readily understood by considering a telephone system in which the invention is embodied. One such system is illustrated schematically in the drawing which forms a part of this specification. The invention is not'limited in its application to the system shown in the drawing but may, in general, be applied to any system which includes one or more polystation lines, the `subscribers stations of which are each provided with a magneto forsignaling other stations on the same nline Referring to the drawing, A, B and C represent local battery subscribers stations connected to a polystation single-wire line I2, D and E represent other subscribers stations in the system, L-iZ represents apparatus individual to the line I2 in a central office, LF-I and LF-Z represent 1 line-finder switches in the central oice, and, -SC-l and SC-Z represent selector-connector switches in this office.

Each of the pclystation-line subscribers stations comprises a receiver 9 and transmitter 'I, a dial impulse sender I I, and a magneto Ill. The subscribers stations D and E are shown as being common battery stations, the station E being equipped with'a dial impulse sender for use in establishing desired connections. The line apparatus L--IZ comprises a line relay I9, a ring-up relay 2|, a cut-through relay I5, a cut-through delayrelay I4, impulse relays and 26, an auxiliary impulse relay 2l, a slow-to-release relay 28, a cut-off relay 23, a release-control relay I8,

a repeating coil I6, and an interrupter mechanism which is represented by the magnet 3D and two sets of contact springs 3I and 32. For use only when a station on line I2 is called from a station `on some other line of the system, the line apparatus T r-IZ also includes an incoming-call line relay 4I, slow-to-release relays 42 and 43, a cut-off relay 24, a busy-test relay 45, a reversing relay 46, a ringing-control relay 48, and a ringing-code switch which is represented by stepping magnet 50, release magnet 53 and bank 5I.

The line-finder and selector-connector switches LF-I, LF-2, SC-I and SC-2 may be of the well-known Strowger type and reference may `be had to my Patent No. 1,910,972, granted May 23, 1933 and to Patent No. 1,941,085, granted to A. E. Hague et al. December 26, 1933 for a more complete description of the operation and control of the selectornconnector switches. For a description of the operation and control of a Strowger type switch when used as a line-n'der, reference may be had to my Patent No. l.,'?99,554, granted April 7, 1931. If the system includes a large number of lines, additional selector switches may be required for the establishment of desired connections and the selector-connectors SC-I and SC-2 will in that case be replaced by a connector switch. Reference may be had to Automatic Telephony by Smith and Campbell, 2nd edition, pages53 to 65, inclusive, for a de# scription of the operation and control of a Strowger type switch when used as a connector or selector.

Assume first that a call is originated at station A of the polystation line I2 and that station D is the called station. Upon removal of the receiver from the receiver hook at station A, a circuit is closed from ground through the impulse contacts of dial II through the receiver 9 and left winding of the induction coil 8, left upper contact of the receiver hook, over line I2 to the central ofhce, through the back contact of relay 48, normally closed contacts of ythe upper continuity springs of relay I5, and through the winding of relay I9 to battery. Relay I9, being operated by the current in this circuit, closes a circuit for operating the slow-to-release relay 28. The operation of relay 28 connects ground potential to conductor 29, to prevent seizure of the line L-I2 on an incoming call by a selectorconnector SC-Z, and closes a circuit for operating the start magnet 30 of an interrupter which is common to a plurality of lines. The interrupter contacts 3| and 32 are each periodically .closed for a short interval, for instance .2 of a second, the interval between closures being of such a length, for instance ve seconds, that a subscriber who has removed his receiver to ascertain whether or not the line is in use before operating the magneto to call another station on the same line will have replaced the receiver before an idle line-finder begins hunting for the terminals belonging to this line, as

.hereinafter described. Each closure of interrupter contacts 3| begins when a closure of contacts 32 ends. As soon, after relay I9 operates, Vas interruptor contacts 3| are closed, the cutthrough delay relay I4 is operated by the current iny a circuit through its upper winding, middle lower front contact of relay I9, inner lower back contact of relay 2| and the interrupter contacts 3|. Relay I4 closes a locking circuit through Yits lower winding and lower front contact, upper front contact of relay I9, over conductor 29 to ground at the upper front contact of relay 28. W'hen interrupter contacts 32 next close, several seconds after relay I4 operates, a circuit is closed through contacts 32, the lowermost front contact of relay I4, back contact of the lower continuity spring of relay I5, upper back contact of relay 2| and through the Winding of relay I5. Relay I5, operated by the current in this circuit, locks through the front contact of its lower continuity spring over conductor 29 to ground at relay 28, opens the operating circuit for the interrupter start magnet 30, disconnects the Winding of relay I9 from the line I2 and closes a circuit over line I2, through the front contact of the upper continuity spring of relay I5, upper back contact of relay 21, winding of relay 26, and through the upper Winding of relay 25. Thus the operation of relay I5 causes the release of relays I9 and I4 and the operation of relays 25 and 26. Relay 26 closes a circuit for holding relay 28 operated after relay I 9 releases and bridges the right winding of repeating coil I6 across

conductors

33 and 34. Relay 25 closes a circuit for operating relay 21 and relay 21 locks in parallel with relay 28. Since the inner lower front contacts of relay 25 are in parallel with the upper back contacts of relay 21, the operation of relay 21 does not cause the release of relays 25 and 26. With relay 21 operated, the lower winding of relay 25 is connected in parallel `with its upper Winding and ground is connected through the uppermost front contact of relay 21 and the inner lower back contact of relay 24 to conductor I3 to start an idle linender, which is represented by the finder LF--I, to establish connection with the line apparatus L-I2. With relay 25 operated, the winding of cut-01T relay 23 is connected through the inner upper front contact of relay 25 and the lowermost back contact of relay 2|, over conductor 35, to the sleeve terminal of the set of terminals in the bank of each of the associated linenders.

When a line-nder LF-I finds and connects to the terminals to which the

conductors

33, 34, 35 and 36 are connected, ground potential is connected through the sleeve brush of the linefinder to sleeve conductor 35, the cut-01T relay 23 being thereby operated in the usual manner. Relay 23 disconnects ground from conductor I3 and connects its winding to sleeve conductor 29 so as to be held operated independent of the ground potential which caused its operatiorr. With relay 26 held operated in series with line I2,l the right winding of repeating coil I6 is connected through

conductors

33 and 34 and the brushes of the line-nder LF-I to the windings of the line relay (not shown) of selectorconnector SC-L Dial tone is thereupon transmitted from the selector-connector SC-I to the calling station and nothing further occurs until the subscriber at station A dials the number of the station with which connection is desired. The off-normal (upper) contacts of the dial II are effective to open the'transmitter circuit and short-circuit the receiver while each series of dial impulses is being transmitted. Relay 26 is fast in operating although the line I2 be of high resistance. The energization of the lower winding of relay 25, upon operation of relay 21, is in velectromagnetic opposition to the energization of its upper winding, the resultant energization being only sufcient to hold the relay operated. 'I'he release of relay 25, each time the line circuit is opened at the dial contacts, is thereby insured,

although the line insulation resistance be low.

The rst opening of the line circuit by the dial is, therefore, effective to cause the release of relay 25; and the release of relay 25 causes the release of relay 26, the windings of relays 25 and 26 being entirely disconnected from the line when relay 25 releases and until relay 21 releases. The release of relay 26 opens the holding circuit for relay 21 and opens the bridge across

conductors

33 and 34 to cause the release of the line relay (not shown) of selector-connector SC-I. The closing of the line circuit at the end of the rst dial impulse causes the reoperation of relays 25, 26 and 21 in the order named thereby again closing the bridge across

conductors

33 and 34 to cause the reoperation of the line relay of the selector-connector SC-|. Relay 28 is slow-in-releasing and remains operated during dialing. Each succeeding opening and closing of the impulse contacts of the dial causes the release and reoperation of relays 25,

26 and 21 whereby the impulses are repeated by the uppermost contacts of relay 26 to control the operation of the selector-connector SC-I. Upon completion of the desired connection and answer of the called subscriber, the talking circuit includes repeating coil I6. When the subscriber at station A replaces the receiver on the receiver-hook, relays 25, 26 and 21 release. Since relay 26 does not reoperate, relay 28 releases thereby causing the release of relay I5 and A thereupon operates the magneto I0 to call the desired station. The ringing current, thus generated, is also effective to operate the ring-up relay 2| in the central oice, the winding of this relay being connected through condenser 23 to `line I2. Relay I9 may respond to the magneto ringing current. Relay 2| locks, through its upper front contact to ground at the lowermost back contact of relay I5 and closes a circuit for .operating relay 28 to protect the line apparatus L-I2 from seizure on an incoming call. When the receiver is again removed at station A` to converse with the called station, relay I9 reoperates. If interrupter contacts 3| are closed When relay 2| operates, the upper winding of relay I8 will be energized; but as soon as relay' I9 reoperates, relay I8 will be released, With relay 2| operated, the operation of relay I9 is` ineffective to cause the operation of relay I5. When the conversation is nished, relay I9 releases and as soon thereafter as the interrupter contacts 3| are closed, the upperl winding of relay I3 is energized and relay I8 operates. Relay |8 locks through its. lower winding and lower front contact, through a back contact of relay I9, over conductor 29 to ground at relay 28. When the interrupter contacts 32 are next closed, a circuit is closed through the upper front contact of relay I8 for operating relay I5. The operation of relay I5 causes the release of relay 2|; and the release of relay 2| causes the release of relay 28. With relays 2| and 28 released, relaysx|84 and I5 also release, the line apparatus then being normal ready for use on another call.

If a call is originated by removing the receiver at any station of line I2, and, after extension of the line by a line-lnder such as LF-I to a selector-connector, the calling subscriber does not dial, the selector-connector operates as described in the aforementioned Patent No. 1,941,085 to connect ground potential to the fourth or control conductor of line-iinder LF-I, this ground potential being extended over conductor 38 to cause the operation of relay 2|. The operation of relay 2| causes the release of relay I5; and the release of relay I5 closes the locking circuit for relay 2| and reconnects relay I9 to the line I2. The reoperation of relay I9, with relay 42|l operated, connects ground through the inner lower front contacts Yof these relays, to operate the permanent signal alarm ap-paratus 22. Upon termination of the permanent signal condition, the line apparatus L-IZ is restored to normal as described in the preceding paragraph.

If a subscriber at some other station E calls a station on line I2, the calling` line is extended by means of a line-finder LF-Z and a selectorconnector SC-2 to conductors 3l' and 38, thereby closing a loop circuit for operating the incomingcall relay 4I. Relay 4| closes a circuit for4 operating relay 42 and relay 42 connects a busy-indieating ground potential to sleeve conductor 29 to prevent seizure of the line on another call, to` hold-the selector connector SC--2, and to cause the operation of the auxiliary cut-olf relay 24. Relay 24 locks through its inner upper front contact directly to conductor 29, closes a circuit for operating relay I5, and connects the right winding of repeating coil I6, through con- 5 densers 60, to conductors 3l and 38. Relay I5 disconnects line I 2 from relays I9 and 2| and connects line I2 to relays 25 and 26, which relays are thereupon operated. Since the auxiliary cut-01T relay 22 is then operated, the oper- =l0 ation of relay 2'I is ineffective to cause the starting of a line-nder.

Since the line apparatus L-I2 is arranged to control the ringing of the various stations on line I2, the selector-connector SC--Z differs from that described in the above-mentioned Patent No. 1,941,085 in that it lacks the ringing-control apparatus. The dial impulses created bythe dialing of the ringing-code digit are repeated by the selector-connector SC-2 to cause the alternate release and reoperation of relay 4I. The first release of relay 4| closes a circuit for operating relay 43 and rotary stepping magnet 5U; and the reoperation of relay 4|, at the end of the rst impulse, causes the release of magnet .25 58. The operation of magnet 50 advances the brush 5| of the ringing-code selector one step. The off-normal contacts ON are shifted when the selector is moved out of normal position, the circuit for relay 43 and magnet 59 being thereupon changed to include the lower front contact of relay 43 instead of the lower contacts of the ON springs. Each succeeding release and reoperation of relay il causes a corresponding operation and release of magnet 5I), the brush 5I being advanced one step by each operation of magnet 5B. Relay43 is slow-in-releasing and remains operated until all of the ringing-codedigit impulses have been received. Relay l42 is also slow-in-releasing and does not release during the responseof relay I to the dial impulses. The aforementioned operation of relay 43 also closes a circuit for operating relay 45; this circuit includes the uppermost front contact of relay t3, the lower back contact of relay 2'I, conductor 23 and the upper front contact of relay 42. Relay 45 locks through its upper front Contact and opens the connection between the repeating coil Iii and conductor 38. The brush of ringing-control interrupter drum 55 is connected to ground during the ringing interval of all the different ringing codes; and, if relay 43 is operated during the time this brush is connected to ground, relay i5 operates. If relay 43 releases before ground is disconnected from the 55 brush of drum 55, relay I4 is held operated through its upper front contact, the lower front contact of relay 45 and the back contact of relay 43. Relay I4 and interrupter drum` 55 are thus effective, in combination with

relays

43 and 45, to prevent the operation of relay 48 at any time other than at the beginning oi a ringing cycle. With relay It reieased, relay 48 is operated at the beginning of the next ringing cycle to disconnect line I2 from the windings of relays 25 ,65 and and connect line I2 through brush 5I and the terminal lwith which it is in contact, through the ringing interrupter 5? tothe ringing source: 53. The `particular ringing code selected by brush 5i is thereby transmitted over line I2, 70 the ringer-s at all of the stations on the line being operated. The brush 5i of the code selector is. shown as having ten terminals; if more than ten stations are connected to line I2, a `code selector with a larger number of terminals would g5 -be provided, in which case the ringing code would .consist .of more than one digit. A ringing tone is transmitted through condenser 49 to the calling station E. The release of relay 48 .at the end -of the ringing interval reconnects 'line I2 to relays 25 .and 26. Since the high resistance, high .capacity .and low insulation resistance of single- --wire lines are such as to make it impossible to use -a ringing cut-off relay in series with the line, it is necessary to reconnect the line to the sensitive impulse relays 25 and 26 at the end of each ringing cycle for operation if the receiver has vbeen removed at the called station. Relay 48 1s slow-in-releasing so as to permit discharge of 'the ringing condenser at the various stations before the line I2 is reconnected to relays 25 and 2.6, to guard against false operation of these relays. When the receiver is removed from the receiver-hook at the called ystation and as soon thereafter as relay 48 releases, yrelays 25, 26 and 21 are operated. The operation of relay 21 causes the release of relay 45` thereby preventing `the reoperation of relay 48 when the brush of interrupter drum 55 is next connected to ground. The release of relay 45 also completes the talking circuit through the right winding of repeating coil I6. The operation `of relay 25 closes a circuit for operating the reversing relay 45. The operation of relay 28 causes the operation of relay 28. When the connection is released by the calling subscriber, relays 4I, 42 and 46 release.` The release of relay 42 causes the operation of releasemagnet 53 thereby restoring the ringing-code selector to normal. When the receiver is replaced at the called station, relays 25, 26, 21 and 28 release. The release of relay 25 causes the release of relay 46, if operated. With both of relays 42 and 28 released, ground is vdisconnected from sleeve conductor `25! thereby causing the release of relays 24 and I5.

What is claimed is:

ll. In a telephone system, a line, a subscribers station, an impulse sender at said station, an impulse repeater for said line and no other, and circuit means responsive to the removal of the receiver from the receiver-hook at said station for operatively extending said line to said impulse repeater.

2. In a `telephone system., a single-Wire line, -a subscribers station, an impulse sender at said station, an impulse repeater for said line and no other, and circuit means responsive to the removal of the receiver from `the receiver-hook at said station for operatively extending said line to said impulse repeater.

3. In a telephone system, a line, a subscribers station, an impulse sender at said station, an `impulse repeater individual to said line, circuit means effective a predetermined interval of time aftr the removal of the receiver from the receiver-hook at said station for operatively extending said line to said impulse repeater.

4'. In a telephone system, a line, a subscribers station,` an impulse sender at said station, an impulse repeater individual to said line, a line relay for responding to the removal of the receiver from the receiver-hook at said station, a switching relay for operatively extending said line to said impulse repeater, and circuit means effective a predetermined interval of time after the oper- 4ation, of said line relay for operating said switching relay.

5. In a telephone system, a line, a subscribers station, an impulse sender at said station, an ,impulse repeater individual to said line, .a line vrelay for responding :to the removal lof the receiver from the receiver-hook at said station, a

yswitching relay for transferring said line from said line relay to said impulse repeater, and circuit means eifective a predetermined interval of time after the operation of said line relay for operating said switching relay.

6. In a signaling system, a line, an impulse sender, an impulse relay, an auxiliary impulse relay, -a signaling circuit comprising said `line and .sender and windings of said impulse relays 1n series, said impulse relay being `adjusted to operate in series with a line of low conductivity and said auxiliary impulse relay being adjusted to release in series with a line of low insulation resistance, a third relay, a circuit closed by :the operation of said second relay for operating said third relay, a circuit for holding said third relay operated until said` impulse relay releases, a second winding of said auxiliary relay differentially energized with respect to its rst winding upon operation of said third relay, and means com.- prising normally open contacts of said second relay for disconnecting said line from the winding of said impulse relay.

7. In a telephone system, a line, subscribers "stations connected to said line, means at each station for transmitting ringing current over the line to signal another of the stations, an impulse repeater for said line, circuit means responsive to the removal of the receiver at any one of said stations for operatively extending said line to said impulse repeater, and means comprising a relay operatively responsive to ringing current over said line for preventing said extension of the line to the impulse repeater.

8. In a telephone system according to claim 7, means responsive to the replacing of the receivers at the calling and called stations on a call between two stations on said line for causing the release of said relay to render said circuit means operative for use on a succeeding call originating at one of said stations.

.9. In a telephone system, a line, subscribers .stations connected to said line, a magneto at each station for transmitting ringing current over the line to signal any other station on the line, a relay for responding to ringing current over said line, .an automatic switch for use in completing a call originating over said line, circuit .means responsive to the removal of the receiver `at any of said stations for operatively extending rsaid line to said switch, alarm signal means, and circuit means including said relay for disconnecting said line from said switch and for operating said alarm signal means.

l0. In a signaling system, a line, an impulse sender, an impulse relay, a second relay, a signaling circuit comprising said line and sender and a winding of each of said relays, said impulse relay being adjusted weak and said auxiliary relay being adjusted stiff, a third relay, and circuit means comprising said second and third relays effective in response to the opening of said signaling circuit for disconnecting the winding of said impulse relay from the line.

l1. In a signaling system, a line, an impulse sender, an impulse relay, a signaling circuit comprising said line and sender and the winding of said relay, and circuit means comprising another relay operatively responsive to the opening of said circuit Afor disconnecting the winding of said impulse relay from said line.

12. In a telephone system, a line, a subscribers station connected to said line, an impulse repeater permanently connected to said line, circuit means responsive to the removal of the receiver from the receiver-hook at said station for operatively associating said line and impulse repeater, and a ydial at said station for creating signal impulses transmitted over said line to said impulse repeater.

13. In a telephone system, lines, a plurality of subscribers stations connected to one of said lines, a magneto at each station for use in signaling the other stations on the line, an impulse repeater for use in establishing a connection between any one of said stations and any other of said lines, a relay connected to said line and operatively responsive to signaling current from any one of said magnetos for preventing the extension of said line to said impulse repeater, and circuit means for disconnecting said relay and for operatively extending said line to the impulse repeater.

14. In a telephone system, a line, subscribers stations connected to said line, each station comprising a magneto and an impulse sender, an impulse repeater individual to said line, circuit means responsive to the removal of the receiver at any one of the stations for operatively extending said line to the impulse repeater, and a relay operatively responsive to ringing current created by the operation of the magneto at any of said stations for preventing the extension of said line to said impulse repeater.

15. In a telephone system, a line, subscribers stations connected to said line, each station comprising a magneto and an impulse sen-der, an impulse repeater individual to said line, circuit means responsive to the removal of the receiver at any of said stations to originate a call for operatively extending said line to the impulse repeater, a relay operatively responsive to ringing current created by the operation of the magneto at any of said stations for preventing the extension of said line to said impulse repeater, and circuit means rendered effective by the return of the receiver to normal position for causing the release of said relay to enable extension of said line to said repeater on a subsequent call.

16. In a telephone system, lines, one of said lines being a party line, a magneto at each of the stations of said party line for use in calling the stations on the line, an impulse sender at each of said stations for use in calling stations connected to other lines, an impulse repeater for use in completing calls from any one of said party line stations tostations connected to other lines, a line relay responsive to the removal of the receiver at any one of said party line stations, a ring-up relay responsive to current created by the operation of the magneto at any of said party line stations, circuit means effective a predetermined interval of time after the operation of said line relay for disconnecting said ring-up relay from the line and for operatively connecting said line to said impulse repeater, circuit means rendered eiective by the operation of said ring-up relay for preventing the extension of said line to said impulse repeater, circuit means for holding said ring-up relay operated during conversation between stations of said party line, and circuit means effective a predetermined interval of time after the return of the receivers to normal at the calling and called stations of said party line for causing the release of said ring-up relay.

17. In a telephone system, lines including a line having a plurality of magneto stations permanently connected thereto, an impulse sender at each of said stations, means comprising impulse controlled switches for use in connecting said line to a desired one of the other lines, an impulse repeating relay for repeating impulses from said sender toI said switches, said impulse relay being individual to but normally disconnected from said line, and means comprising a line relay normally connected to said line and responsive to removal of the receiver at any of said stations for connecting said line to said impulse repeating relay.

RAY L. STOKELY.