US1355917A - Automatic telephone system - Google Patents

Automatic telephone system Download PDF

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Publication number
US1355917A
US1355917A US170337A US17033717A US1355917A US 1355917 A US1355917 A US 1355917A US 170337 A US170337 A US 170337A US 17033717 A US17033717 A US 17033717A US 1355917 A US1355917 A US 1355917A
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United States
Prior art keywords
relay
line
circuit
switch
selector
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Expired - Lifetime
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US170337A
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English (en)
Inventor
George E Schomaker
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Automatic Electric Co
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Automatic Electric Co
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Publication date
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Priority to US170337A priority Critical patent/US1355917A/en
Priority to FR490134A priority patent/FR490134A/fr
Application granted granted Critical
Publication of US1355917A publication Critical patent/US1355917A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements

Definitions

  • My invention relates in general to automatic telephone systems and more particularly to automatic systems of the type commonly known, as two-wire, in which automatic switches at the exchange are controlled over the two sides of a calling subscribers line in series; and the principal object of the invention is the provision of new circuits for selector switches, with a view to rendering them immune from certain inherent defects which prior to my invention have been a source of considerable trouble.
  • the subscribers lines are usually provided with individual line switches, and upon the removal of the receiver at a calling subat the exchange is operated to extend the line circuit through to the first of the numerical trunking switches to be used in establishing the connection.
  • the selected numerical switch commonly known as a first selector, is responsive to momentary interruptions of the line circuit subsequently produced by the operation of a calling device with which the substation is provided.
  • a calling subscriber in removing his receiver to initiate the call, will accidentally manipulate his switch hook so as to send a preliminary impulse over the line circuit immediately after the line switch has operated and before he has operated his calling device.
  • the first closure of the line circuit may be followed by one or more interruptions before the receiver is completely disengaged from the hook.
  • My invention cures the difficulty explained above by providing a selector circuit such that when a connection is ,extended to a selector embodving my invention, a sequence of operations involving the denergization of slow-acting relays takes place in the selector switch before the circuits for the operating magnets thereof are fully prepared, thus introducing a time interval during which interruptions of the line circuit will be of no effect.
  • my invention enables a selector switch wired in accordance therewith to pass over open or defective trunks during the period of idle trunk selection, thus permitting the selector switch to automatically select not only an idle trunk, as is usual, but also a trunk the conductors of which are electrically continuous, and even to a certain extent causing the selector to reject trunks which terminate in selectors not in working condition.
  • the reference character A indicates a calling automatic substation whose line conductors 11 and 12 have been extended through the medium of the individual line switch C to the trunk line terminating in the selector E.
  • the selector E- has been operated to further extend the connection to the trunk line comprising conductors 90, 91 and 92 and terminating in the second selector F, which in turn has been operated to establish connection with the connector H.
  • the line and the release relays 150 and 151 are shown in the drawing.
  • the substation A may be of any approved type such, for examp e, as the substation shown in the British patent to Martin, No,
  • the line switch C and a plurality of similar line switches are controlled in their trunk selecting operations by means of a master switch WlllCh is shown in the drawing and indicated by the reference character I).
  • the master switch D is of the general type of master switch disclosed in the above mentioned British patent to James, No. 26,301 of 1906; being, however, more nearly of the ty e disclosed in the British patent to Martin, 0. 1419 of 1910, also previously referred to.
  • the function of the master switch is to maintain the lungers of all the idle line switches which it controls in position before the terminals of an idle trunk line.
  • the selector switch E in which one of the trunk lines accessible to the. line switch C terminates, is of the Jgeneral type of selector switch disclosed in I S. Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson, and Erickson; the side switch and private magnet being omitted, however, and the circuits being modified in accordance with the two-wire system of control.
  • the circuits are further modified in order to accomplish the objects of my invention, as will be explained fully hereinafter.
  • the second selector F is similar to the first selector E except for slight circuit changes which will bepointed out in the description of the operation.
  • the connector H may be of any type which is adapted for operation in a twowire system of the character described.
  • a connectorsuitable for this pur ose is shown in the atent to Newforth 0. 13901, reissued ril 13, 1915.
  • line relay closes a circuit for the pull-in winding 18.
  • the pull-in winding operates both the plunger arm 15 and the cut-off armature 16; the former, through the medium of its plunger (not shown) forcing the bank springs 30 to 33, inclusive, into enga ement, respectively, with contacts 34 to z inclusive; and the latter disconnecting the lines 11 and 12, respectively, from ground and from the line relay'14.
  • the bank springs 30 and 33 By the engagement of the bank springs 30 and 33 with contacts 34 and 37, respectively, the line conductors 11 and 12 are extended through normally closed contacts of the switching relay 57 to the doublewound line relay of the selector E.
  • the line relay 50 is accordingly energized over the loop circuit including the substation A and upon attracting its armature, closes a circuit for the slow-acting release relay 51.
  • the release relay 51 closes a holding circuit for the line switch C which may be traced as follows: Ground at G working contact of armature 62 and the said armature, conductor 74, contact 70, sprin 71, conductor 73, contact 35, spring 31 and the holding winding 17 to battery. ince the line relay 14 is slow acting, it retains its armature to maintain the pull-in winding 18 energized until after the above holding circuit has been established.
  • a branch of the holding circuit extends by way of conductor 20 to multiple test contacts in the banks of the connector switches having access to the line of substation A where by a ground potential on the said contacts, the line is made busy.
  • relay 53' therefore is not energized upon the closure of the above circuit.
  • Relay 57 is energized and attracts its armatures to the position shown in the drawing, thereby breaking the circuit of the line relay 50.
  • relay 50 closes a circuit for the low resistance slow-acting relay 52 as follows: ground at G armature 60 and its resting contact, resistance 72, working contacts of armature 61, winding'of relay 52, and the winding of the vertical magnet 55 to battery. Owing to the inclusion of the resistance 72 in the above circuit, the vertical magnet 55 is not operated.
  • Relay 52 energizes and at its armature 75 connects ground G to conductor 73 by Way of spring 71, at the same time se arating the said spring from contact 70. y this operation ground G is substituted for ground G in therholding circuit of the line switch C.
  • relay 52 prepares an energizin circuit for relay 53 which will be described shortly.
  • the slow-acting relay 51 deenergizes, its circuit having been broken by the deenergization of the line relay 50.
  • the denergization of relay 51 round G is disconnected from conductor 4 at armature 62 and at the same time the, circuit of relay 52 is brokenat armature 61.
  • relay 57 since the previously described energizing circuit of relay 57 includes the grounded conductor 74, the. circuits of this relay and the relay 52 will be broken simultaneously. Owin to the fact that relay 52 is slow-acting, owever, relay 57 deenergizes first and again closes the circuit of the line relay 50.. Relays 50 and 51 now energize in rapid succession with the result that ground G is again connected to conductor 74. The relay 57 is not again energized, however, for since the slow-acting relay 52 still retains its armatures, ground 2 is connectedto the junction of relays 53 and 57 by way of armature 63, thus short-circuiting relay ,5?
  • relay 53 which may be traced as follows: ground at G working contactof armature 62 and the said armature, armature 63 and its working contact, armature 66 and Its rest- .ing contact, junction point 76, interrupter contact of the rotary magnet 54, and the winding of rela 53 to battery.
  • the u per terminal ofre ay 57 being connecte to junction point 76 and its lower terminal being connected to conductor 74, this relay is 'short-circuited as above mentioned.
  • Relay '53 upon energizing, prepares a circuit for the rotary magnet .54 which will be described later, and at its armature 64 completes a locking circuit for itself by connecting ground Gr to junctionpoint 77 as follows: ground at G, working contact of 80 armature 62 and the said armature, and armature 64 and its working contact to junction point 77.
  • This last described connection or looking circuit is effective to maintain-relay v57 short-circuited and the.
  • relay 53 energized after the denergization of t e slow-acting relay 52 which occurs an instant later.
  • the vertical magnet circuit is closed by-a momentary denergization of the line relay 50, relay 51 remaining energized, and extends as'follows: ground at G armature 60 and its resting contact,'resting contact of armature 69 and the said armature, armature 61 and its left-hand working contact, winding of relay 52, and the winding of-the vertical magnet 55'to battery.
  • This circuit is prepared at the first energization of relay 51, but relay 51 also closes the circuit of relay 57, and this latter relay, upon' energizing, opens the circuit of the vertical magnet at its armature 69.
  • the line relay 50 deenergizes momentarily and sends an impulse from ground Gr over the path previously traced through the relay 52 and the vertical magnet 55 to battery.
  • the vertical magnet operates to raise the switch shaft step-bystep until the wipers 80, 81 and 82 arrive at the horizontal level of bank contacts which constitute terminals of the trunk lines extending to the desired main group of subscribers lines.
  • the slow-acting relay 52 is energized in series with the vertical magnet and retains its armatures in operated position during the series of impulses.
  • the offnormal springs 59 are closed to prepare a circuit for the rotary magnet 54 which circuit is held open, however, during the vertical movement of-the switch by the relay 52.
  • relay 52 denergizes and closes the rotary magnet circuit which extends as follows: ground at G working contact of armature 62 and the said armature, armature 63 and its resting contact, armature 65 and its workin contact, off-normal springs 59, and the winding of the rotary magnet 54 to battery.
  • the rotary ma net operates to rotate the wipers 80, 81 an 82 into engagement with the first set of bank contacts in the level opposite which they were raised.
  • the rotary magnet opens its interrupter contact, thereby breaking the energizing circuit of the relay 53.
  • the relay 53 breaks the circuit of the rotary magnet which accordingly retracts its armature and again closes its interrupter contact. Neglecting for the present any question of 0 en or defective trunk lines, which will e referred to later, the operation now depends upon whether the first trunk line, the terminals of which are now enga d by the switch wipers, is busy or not. I this trunk line is busy, the test contact with which the private wiper 81 is in engagementwill have ground potential upon it, which ground potential will serve to maintain the switching relay 57 short-circuited and also to again energize the relay 53. The rotary magnet circuit is, therefore, again completed and the same cycle of operation is repeated, whereby the switch wipers are advanced into engagement with the next set of contacts.
  • the relay 53 will operate as an interrupter or stepping relay to advance the switch wipers through the medium of the rotary magnet as long as the private wiper 81 continues to engage grounded or busy test contacts.
  • the relay 53 cannot again energize;
  • the switching relay 57 opens the circuit of the release magnet 56 to guard against the release of the switch upon the de'energization of relays 50 and 51; shifts, at its armature 66, the private wiper 81 from connection with its upper terminal and into connection with its lower terminal and the conductor 74; and at its armatures 67 and 68 disconnects the incoming line conductors from the windings of the line relay 50 and extends them instead by way of line wipers 80 and 82, bank contacts 83 and 85, conductors and- 92, and normally closed contacts of theswitching relay 107 to the double-wound line relay 100 of the second selector F.
  • the line relay 100 is accordingly energized over the calling subscribers loop and completes the usual circuit for the slow-acting release relay 101. Upon energizing, re-
  • the calling subscriber may now 0 crate his calling device in accordance with t e second digit of the desired number, thereby producing a series of interruptions in the circuit of the line relay. 100 of the selector F.
  • the line relay 100 is accordingly deenergized a number of times and at each deenergization, transmits an impulse from ground G through the slow-actin' relay 102 and the vertical magnet 105 to attery.
  • the vertical magnet operates to' raise the vswitch shaft step-by-step until the wipers 140,'-141,fand- 142 arrive at the horizontal level of the bank contacts which constitute the 'termi nals of trunk lines extending to the desired roup of connector switches.
  • the slow-actng relay 102 is energized in series with the vertical magnet and retains its armatures attracted during the series of impulses.
  • ground iris replaced by ground G this operation is of no particular consequence just at the present time.
  • the off-normal springs 159 are closed thereby completing an initial energizing circuit for" relay 103 which may be traced as follows: ground at. G", workmg contactof armature 110 and the said armature, armature 111 and its working contact,
  • lay 103 locks'itself to ground G at its upacting relay 102 denergizes at the end of the series of impulses, it completes at the resting contact of its armature 111 the pre-" viously mentioned circuit of the rotary magnet 104.
  • therotary magnet operates to rotate the wipers 140, 141, and 142 into engagement with the first set of bank contacts in the level opposite which they were raised.
  • the wipers are rotated in search of an idle trunk line under control of the private wiper 141 and the steppingrelay 103. Since this operation has een fully test contact of an idle trunk line assumed to be the .test contact 163, the rotation of the switch will cease, and the.
  • switching relay 107 heretofore *sho'rt-circuited either from ground Gr or from grounded bus test contacts, will energize with the fol owing results: At its lower armature the circuit of the release magnet 106 is opened in the usual manner; at its upper armature the connection of the private wiper 141 is shifted as described in the case of selector E; and at its two inner armatures, the line conductors 90 and 92 are disconnected from the windings of the line relay 100 and are ex- 'tended instead by way of the line wipers 140 and 142'and conductors 160 and 162 to the windings of the double-wound line relay '150 of the connector H.
  • the line relay 150 is therefore energized over the calling subscribers line'and completes an energizin circuit for the slowacting relay 151.
  • his latter relay upon energizing, completes'a holdin circuit for the selector F and the other swltches which extend as'follows: ground at G, working contact of armature 115 and the said armature, conductor 161, bank contact 163, pri-' vate wiper 141, and'armature 112 and its working contact to junction point 116; where the circuit divides, one branch extending by way of the winding of relay 107 and the windlng of relay 103 to battery, and the other branch extending by way of i normally closed contacts of relay 102 to the conductor 91' where it joins the previously tracedholding circuit extending back to the selector vE and the line switch 0.
  • the connector H is now operated in response to-the callin of the remainin digits in the desired num er to complete t e connection to the called subscribers line.
  • the relays 150 and 151 of the connector H are deenergizedand ground G is removed from the holdirfig circuit extending back to the selectors to the individual line switch (I.
  • the switching relays 107 and 57 .of these selector switches are accordingly deenergized whereupon the selectors are restored to normal in and E and the usual manner through the medium of their respective release magnets 106 and 56.
  • the plunger of the line switch C is withdrawn from the bank, whereupon all the apparatus involved in the connection will have been restored to ,normal.
  • either of the conductors 90, 91 or 92 may beactually open, the bank contacts in which these conductors terminate in the selector E may be dirty, resulting in a poor wiper contact, or there may be one or more dirty relay contacts in the selector F.
  • the selector switch in a well known twowire system was operated, if ground was not immediately fed back from the selector switch ahead, the operated switch would immediately release. This is an undesirable result, for it makes it necessary for the calling subscriber to call his number over again.
  • a selector switch as the selector E for example, stops on an idle but open trunk line, it does not release but the rotation is started again and continues until the next idle trunk line is reached. If this second selected trunk line should also happen to be open for any reason, the selector switch selects still another idle trunk line, continuing the operation until a trunk is selected which is in working condition.
  • relay 52 closes an energizing circuit for the relay 52 which extends by way of resistance 72, the winding of the said relay 52, and the winding of ,the vertical magnet 55 to battery.
  • relay 52 connects ground .1 to conductor-'73 as a substitute for ground G which is momentarily disconnected an instant later, and also repares a circuit for the stepping relay 53.
  • elay 51 now deenergizes and breaks the circuit of relay 57.
  • the operation of the second selector F in passing over open trunks is practicall identical with the operation of selector under similar conditions.
  • the selector F is wired slightly different from selector E, however, in order to prevent the preliminary operation of the relays when the selector is first connected with; for since in the case of the second selector, there is no occasion for removing the selector from the control of the calling line, such relay 0 erations would serve no useful purpose.
  • he off-normal springs 159 therefore are placed in the circuit of the stepping relay 103 rather than in the circuit of the magnet 104.
  • a selector switch having an operating magnet and a line 'relay, subscriber controlled means for energizing said relay and for subsequently deenergizing the same to close a circuit for said magnet, and means in said switch serving automatically to cause a momentary deenergization of said relay while preventing the energization of said magnet.
  • an automatic selector switch having an operating magnet and controlling relays, means for extending a calling line to said switch, and circuits serving automaticallyto energize every relay in said switch at least once when connection is extended thereto and for preventing at the same time the energization of said magnet.
  • an automatic switch having an operating magnet and a relay,means for extending a connection from a calling line and for controlling said relay, to operate said mag net, and automatic means for reducing the current flow in said 'magnetto prevent its operation for-a definite interval relay has been energized.
  • anautomatic switch In a telephone system, anautomatic switch, a line relay and an operating magnet therefor, means for'seizing said switch and energizing said line relay, means for intermittently deenergizing said line relay to close the circuit of said magnet to operate said switch, and automatic means for preventing the first closure of the circuit of said magnet from operating the switch.
  • an automatic switch means for extending a connection from a calling line to said auto- I matic switch in response to the first closure of a line circuit, a line relay and operating magnet for said switch, said line relay controlled by subsequent interruptions of said line circuit to close a circuit for said operating magnet to operate said switch, and automatic means for rendering said line relay nonresponsive to any interruptions of the line circuit which may occur for a certain time interval after the first closure of the line circuit.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
US170337A 1917-05-23 1917-05-23 Automatic telephone system Expired - Lifetime US1355917A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US170337A US1355917A (en) 1917-05-23 1917-05-23 Automatic telephone system
FR490134A FR490134A (fr) 1917-05-23 1918-05-21 Perfectionnements aux systèmes téléphoniques automatiques

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US170337A US1355917A (en) 1917-05-23 1917-05-23 Automatic telephone system

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FR490134A (fr) 1919-04-03

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