US1638513A - Automatic telephone system - Google Patents

Description

Aug. 9, 1927. 1,638,513

R. F. STEHLIK AUTOMATIC TELEPHONE SYSTEM Filed Sept. I5, 1925 In' Ue I @WET-T hama Allg. s, 1921.

UNITED STATES PATENT OFFICE.

RUDOLPH l'. BTEELIX. OIOHIOAGO, ILLINOIS, ABBIGNOB, BY ASSI@ TO AUTOITIO BLBOTBIO INC., 0l' CHICAGO, ILLINOIS, A CORPORATION Ol' Dm AUTOIAIIO TELEPHONE SYSTEM.

Application led September 8, 1925. Serial lo. 54,188.

two directional type of rotary connector re sponds to two digits transmitted to it, the first digit positioning the wipers opposite the level of bank contacts in which the desired group of trunks is located, while the second digit positions the wipers on the first `bank contact of the desired group. The switch then automatically rotates its wipers until the engage contacts with which an idle trun is associated. If all trunks are bus the switch continues to rotate until it arrives at the last bank contact of the group and then transmits thel busy tone to the calling subscriber.

`The ordinary two directional type of switch has access to ten levels, each comprising ten contact sets and, therefore, this arln rangement Works ve nicely where the trunk groups are ma e up of ten or less trunks. In cases where rivate branch exchanges are of such capacity that ten trunks are insuflicient to take care of the traflic the branch exchange is given two directory numbers. This is objectionable in that if a subscriber desires to connect with the branch exchange it may be necessary to dial both directory numbers owing to the fact that the first group of trunk lines by way of which the subscriber attempted to attain access to the private branch exchange was busy.

In a Wicks Patent No. 1,603,929, patented October 19, 1926, this objectionable feature 46 was overcome by adding vertical test equipment and by modifying the rotary connector circuits so that when grou s of over ten trunks were desired the switc was arranged to move its wipers from the level to which they were operated directively to the next level in case all trunks in the first level were busy. The resent invention, however, overcomes the obJectionable feature by merely switchinvr from one set of wipers to another, whic method in some installations has proved the more desirable.

The present invention also enables the assignment of highly desirable directory numbers to large branch exchanges using more than ten trunks. In the connectors formerly used, as previously stated, the connector switches o crate responsive to two digits, the first digit ein utilized to elevate the wipers to particular evel and the second digit being utilized to position the wi ers into engagement with the contacts of t e first trunk of a desired group. In the present disclosure in callin trunk groups comprising less than ten trun s, the operation is the same as formerly. If, however, the trunk group exceeds ten, the last digit may be selected to suit the whim of the private branch exchange subscriber, as this digit is not necessary and is absorbed.

The accompanying drawing shows suiicient of a telephone system to enable the invention to be intelli ently described. More specifically the drawing discloses a connector of the `well known vertical and rotary type with the circuits modified in accordance with the invention. The shaft (not shown) caring the usual wipers is, of course, also e ongated to provide the necessary space for the added Wipers which are necessary to the carrying out of the invention.

In order that a thorough understanding of the invention may be had, a descri tion will first be given of the manner in whic the connections are'set up from the calling station to a private line and to a tprivate branch exchange trunk line terminating in a group comprising less than ten trunk lines, respectively, after which it will be explained how any one of twenty trunks may be selected.

The usual subscribers substation, individual line switch and selector switches used by a subscriber in completing a connection being well understood by t ose skilled in the art and since this equipment forms no part 100 of the invention, it is believed it will suffice to say that the calling subscriber upon removin v the receiver from the switchhook causes his line switch to extend the calling line conductors into connection with an idle selector. The subscriber then operates his calling device in the usual manner causing his line to be extended to a second selector or to a connector such as the connector E, depending on the capacity of the system.

Let us assume that the calling subscriber has set up the connection as far as the last selector and that the wipers of that selector have come to rest on the bank contacts, which are connected to conductors 23, 24, and 25, resulting in the switching relay of the selector completing an energizing circuit for the line relay 26 of the connector E. The line relay 26 upon energizing in turn causes the energization of slow release relay 28. Relay 28, in operating at its armature 39 supplies ground to the release trunk conductor 24 to maintain the previously operated switches operated in the usual and well understood manner. Relay 28 at its armature 38 prepares holding circuits for various relays as will be explained hereinafter and at armature 37' prepares a circuit for vertical magnet 40 and slow release relay 29.

We will first assume that the last two digits of the desired subscribers number are 1 and 9, respectively. The subscriber, therefore, dials the digit 1 causing line relay 26 to drop back momentarily to transmit an impulse by way of its grounded armature and resting contact, armature 37 and its working contact, ofl'I normal spring 88 and its resting contact and the winding of relay 29 and vertical magnet 40 to battery. The vertical magnet functions in the usual manner to elevate the wipers 7 4 to 81, inclusive, a number' of steps corresponding to the number of impulses transmitted to the line relay 26, which in the present case was l, and causes the operation of the ott normal springs 87 and 88.

Shortly following the transmission of the impulse to vertical magnet 40, slow release relay 29 restores and at its armature and back contact prepares an operating circuit for slow release relays 33, 34, and the rotary magnet 42. Responsive to the dialling of the digit 9, the line relay 26 causes nine impulses to be transmited from its grounded armature and back contact, armature 37 and its working contact, springs controlled by off normal spring 88, armature of relay 29 and its back contact, back contact and armature 48, the windings of relay 33 in multiple to point 100, where the circuit divides, one branch extending by way of the back contact and armature 53 to the winding of slow relay 34 and battery; the other branch extending by way of armature 62 `cept the last line of the group.

and its resting contact and the rotary magnet 42 to battery.

Relays 33 an 34 are slow to release and,

therefore, although the circuit of relay 34 is transferred, upon the energization of relay 33, from that just traced so that it obtains ground direct from armature 53 and the Working contact of relay 33, this relay does not deenergize until following the deenergization of slow release relay 33, which also remains energized until an interval after the entire series of impulses have been transmitted to the rotary magnet 42. Relay 34 at its armature 57 and its working contact connects the test wiper into electrical connection with the winding of test relay 32. Relay 33 at its armature 56, completes a circuit around armature 48 and its resting contact so as to avoid the im ulsing circuit being interru ted should t e test relay be operated whi e wiper 75 is passing over busy or rounded test contacts.

Assuming t at the desired line is busy at the present time, there will be a ground potential present upon the test control 101 engaged by the test wiper 7 5 and the test relay 32 will be energized. Relay 32 upon operating at its armature 52 prepares a locking circuit for itself which is completed upon the deenergization of slow acting relay 34, and at its armature 73 places a busy tone on the lower heavy talking conductor whereby the calling subscriber is notified that the desired line is busy. The calling subscriber will accordingly replace his receiver upon the switchhook thereby initiating the release of the operated switches.

It will non.r be assumed that the line of the desired substation is one of a group of trunk 'lines listed under the same directory number, for instance, it may be assumed that the last two digits of which is 21. In this case the circuits of the connector E must be slightly changed in order to enable it to select therfirst idle one of these lines. This is accomplished in the usual manner by connecting the test contacts 92 and 93. similar to test contacts 101 and 102, together on all ex- Under thescJ conditions when a line becomes busy, ground is present upon both these test contacts. As shown the 'test contacts 92 and 93 and the three subsequent sets of test contacts are so connected. Now, if it is assumed that the first trunk Was busy when connection was attempted, the test relay 32 will become energized as before described and will operate and prepare a locking circuit for itself at its armature 52 as before, and in addition, since contacts 92 and 93 are tied together. at its armature 51 prepares an operatingr circuit for stepping relay 31 which is com leted iinmediately upon the restoration o relay This circuit for stepping relay 31 extends by way of grounded wiper 74, resting coutact and armature 68, workin contact and amature 58, armature 51 an its working contact, resting contact and armature 54. interrupter springs of rotary magnet 42 and the winding of relay 31 to battery. Relay 31 upon operating' at its armature 45 and its working contact completes a locking circuit for itself, and at armature 46 and itsworking contact prepares a locking circuit for slow release relay 34 which will be completed immediately upon the restoration of slow release relay 33. A branch of the circuit` for relay 34 also includes a new circuit for the rotary magnet 42 extending from the grounded spring controlledby armature 53, Working contact and armature 46, armature 62 and its resting contact and the winding of rotary magnet 42 to battery. Upon comp'letion of this circuit rotary magnet 42 bccomes energized and at its interruptor sprin s opens the circuit of stepping relay 31, W ich, ipon energizing at its armature 46, opens the circuit of rotary magnet 42. causing this magnet to deenergize. The alternate operation of stepping relay 31 and rotary magnet 42 now continues to take place as long as grounded test contacts 92 are engaged.

If all of the lines of the group are busy, since the last test contact set similar to 92 and 93 are not tied together, there will be no ground potential present on the test contact engaged by the test wiper 74. The test relay 32 will, therefore. be the only relay operated and no further rotary movement can take place, instead the busy tone will be given to the calling subscriber in the same manner as was described in the case where a subscribers line was called.

It will now be assumed that the first line of the group was idle when connection was attempted therewith by the connector E. Under vthese circumstances there will be no ground potential present upon test-,contact engaged by wiper 75 and, therefore, no circult is completed for test relay 32, or stepping relay 31. Accordingly, followingr deenergization of slow release relay 34, a circuit is completed extending from grounded working contact and armature 39, armature 52 and its resting contact, upper winding of switching-relay 35, resting contact and armature 57, armature 69 and its resting contact. test wiper 75 to battery supplied through the winding of the motor magnet of the incoming individual line switch associated with the line for extending connections to the branch exchange. Relay 35, upon energizing, at its amature and its' working contact completes a locking circuit for itself by way of armature 38 and its 'grounded working contact, opens a point in the operating circuit of wiper switching relay 36 at its armature 66, at its armature 64 opens a point in the operating 'circuit of busy relay 32, at its armature 63and its working contact connects direct ground to the private wiper 75 to render the 'line busy to other subscribers, at its armature 60 and 60'A connects interrupted generator and ground, respectively, to the line conductors by way of wipers 78 and 79, at armature 62 opens a point in the operating circuit of rotary niagnet 42 and at armature 61 cuts in a low capacity condenser in the upper conductor so that the calling subscriber may hear the signaling'operation take place.

When the called subscriber or attendant operator of thev rivate branch exchange answers, a circuit fdr the ring cutoff relay 30 is completed over the called loop. Relay 30, upon energizing, establishes a locking circuit for itself at its armature 43 in multiple with that described for the switching relay 35 and at its armature 44 and 47 cuts oft' generator and ground, respectively, from the conductors of the callin line and connects these conductors throng to finally complete the talking connection. The back bridge relay 27 is immediately energized over the line of the substation ory attendant operators equi ment and suppliestalking current to tllie called subscriber, and at its armature 10S and working'eontact connects ground to the holding conductor 105 so as to maintain the connector E operated as long as either thc calling or called line has his receiver oli the hook.

We will now assume that connection is desired with a private branch exchange over any of twenty trunks available to the connectorJ), orslmilar switches, but before proceeding with this description it. is consdered advisable to briefly explain the manner in which the switch is arranged to accomplish this result without increasing its capacity. In illustrating the invention it will be assumed that the particular branch exchange in question has been given the desirable directory numberl of 5000 and, therefore, when the first digit 0 is transmitted to the cou nector the wipers 74 to 81, inclusive, will be elevated ten steps. The wiper 76-77. and 80-81 are located six steps or levels below the respective wipers 74-75 and 78h79 so that when digit 0 is dialed and the wipers 74-7 5 and 78--7 9 are opposite the 0 or tenth level of the bank contacts, wipers 76-77 and 80-81 are opposite the fourth level of bank contacts. From this it will be appreciated that the twenty trunks available in the present instance are the 10 located in the tenth level and the 10 located in the fourth level of the switch E. Since the number of rotary steps or the number of trunks in any one level is limited to ten. the tenth bank contact in each instance that is, in the 0 level and in the fourth level, are not multipled. The remaining private contacts of the entire group are multipled or' joined together in the same manner as was explained inconnecton with trunk groups of less than ten. Connected with each test contact of the 0 level, such as that corresponding to 93 of the 0 level, are chain relays and the circuits are so arranged, as will subsequently be described, tliat if, when the switch is elevated to the 0 level, all trunks in that level are busy, the conductor 86 will be grounded, normal post spring will be closed and a circuit will be completed for wiper switching relay 36. This relay will then be locked up and trunk selection will take place on the fourth level in the same manner as if there were only ten trunks available to the branch exchange.

The operations which take place in the selection of a trunk of a large group, as" briefly described in the foregoing will now be described in detail. The connector E is seized in the previously described manner and the switch operated responsive to the transmission of the digit 0 to step its associated wiper sets to the tenth and fourth level, respectively. The switch upon taking its tenth step operates shaft springs 50, 55, and 70. The closure of the springs 50 prepares a point in the circuit of wiper switching relay 36, the opening of springs opens the low resistance path to the lower winding of slow release relay 33, while the .springs 0 prepare a point in a new operating circuit for stepping relay 31.

Upon the next and final digit 0, being transmitted to the connector E, relavs 33 and 34 operate in the manner formerly described. Relay 33, however, in this instance, due to the operated condition of normal post springs 55 is energized through its high resistance winding, which prevents the impulses operatively aifecting rotary magnet 42. At this time, since normal post springs are also closed, as soon as armature 54 operates, a circuit is completedfor the stepping relay 31 by way of grounded armature 63 and its resting contact, normal post springs 7 0, Working contact and armature 54. interrupter springs of rotary magnet 42 and the winding of stepping relay 31 to battery. Shortly following the transmission of the last impulse relay 33 restores and at springs controlled by armature 53 completes the previously described circuit for rotary magnet 42. The operation from this point depends on whether all the trunks in the 0 level are busy or not. If any one trunk is idle no ground will be'present on conductor 86, the operation of normal post spring 50 will be without effect and the switch will operate to cause the selection of an idle trunk in the 0 level in the same manner as described when trunk selection took place in the second level.

lf, however, all the trunks of the 0 level are in use, the conductor 86 will be grounded by the chain relays 11k-120 and as a result of the closure of normal post springs 50, a circuit will be completed by way of armature 49 and its back contact, back contact and armature 66, and springs controlled by armature 71 for the wiper switching relay 36, which will immediately operate. Relay 36 at its armatnrer71 completes a locking circuit for itself and at armature 67, 68, 69, y

and 72 switches the various conductors of the switch E from connection with the wipers normally used to the auxiliary wipers 76-77 and 80-81, which as previously explained are op osite the fourth level of their respective ban s. The trunk selecting operation is not changed by the switching 0f the wipers and takes place in the same manner as described in the foregoing.

It will be assumed that the twentieth trunk, the tenth trunk of the fourth level, is the only trunk idle. When the wipers 7 6 and 77 reach the test contacts with which this trunk is associated, no ground being present on test Contact 121, busy relay 32 will not be energized, but following the deenergization of slow release relay 34 the previously described circuit for switching relay 35 will be completed resulting in the connection previously described.

When the conversation is terminated both the subscribers will replace the receivers upon their respective switchhooks. When the receiver is replaced at substation A, the circuit for line relay 26 and slow release relay 28 will be opened. The deener 'zation of relay 28 causes the calling subscri rs line switch and any intervening selector switches to be restored to normal and also causes ground to be removed from one point of conductor 105, to prepare the circuit for release magnet 122. The switch E is not released, however, until both parties have restored their receivers owing to the fact that the release magnet circuit is still open at armature 109 of the back brid e, relay 27, and the holding conductor 105 or the various relays of the switch E is maintained grounded by armature 108 and its working contact. When the called subscriber replaces his receiver the back bridge relay, however,

being completed in the manner restores to normal causing the release magnet circuit to be completed and the holding circuit for relays 30, 36, and 35 to be opened, these relays and the switch E accordingl restore to normal, rendering the trunk avai able for further calls.

In the foregoing description it was assumed that the entire maximum of twenty trunks were utilized as a single grou In many cases a smaller number of trunhs are suilicient. For instance, 'in the case illustrated there mi ht have been only the first five trunks avai able to the auxilia wiper set in the fourth level, the remaining ve fill contact sets being utilized as another trunk Uroup accessible to the regular wiper set. urtherinorc, if, the re ular wiper set has rovided below it auxi iary wipers located ve steps below them instead of six, as illustrated, the switch may be utilized to connect with any of live groups of over ten trunks each and also be able to select any one of five ormore groups comprising less than ten trunks. in which case it will be understood that the small trunk groups would be located in the righthand portion of the live lower bank contact sets and be selectable only by the regular wiper set. In such an arran ement the normal post sprinvs 50, 55, and 0, instead of operating on tlie 0 level only, would operate on the sixth toteiitli or 0 level inclusive.

From the foregoing it will be appreciated that applicant has desiriied a rotary connector having features ighly desirable in cci-tain instances over former switches of this type.

What is claimed is:

1. In a telephone system, a connector switch havin two sets of wipers, a plurality of levels of bank contacts accessible to said wiper sets. means for directively operating said switch to cause each of said wi er sets to be positioned opposite a different evel of bank contacts, means for causing said' wipers to successively engafre all the contacts in the level opposite which they have been positioned, lines terminating in said bank contacts, means for making said lines busy, means normally causing only one set of wipers to test for an idle line as it successively engages its bank contacts, and means for causingr only the other wiper set to test if all lines available to the first wiper are busy.

2. In a telephone system, a connector having two sets of wipers, lines divided into groups and subgroups accessible to one of said wiper sets only, and other lines divided into groups and subgroups accessible to both wiper sets, means for directivel operating said connector in a primary irection to select a group of lines available to one of said wiper sets, and means eilective in case all lines in said group are bus for rendering the other wiper set availab e to select an idle line of a second group.

S. In a telephone system, an automatic switch ot the two directional type, a plurality of wiper sets. a bank of contacts dividcd into a plurality Iof groups, lines terminating at. said contacts, directive controlled means for elevating one of said Wiper sets opposite one group of said contacts and for simultaneously moving the other wiper set opposite a second group of contacts, means for causing said switch to move both wiper sets to select an idle line of a group and automatic means effective after the directive automatically test for ani e trunk in ono of said groups responsive to any digit im pulse or impulses transmitted to it, and means effectiyjfonly in case all trunks in one group aile'busy for causing the lines in the other grou to be tested.

5. In a telep one system, a rotary connector switch, lines accessible to said switch, said switch responsive to a series of impulses to cause the selection of a particular group of said lines, means subsequently responsive to only one impulse of a subsequent impulse series to cause one of the lines ot' the selected group to be connected with irrespective of the busy oil idle condition of the first lines in the selected group and means in said switch for absorbing the remaining impulses of the last impulse series.

6. In a telephone system a connector switch, groups of lines terminating in bank contacts ot' said switch. said switch responsive to one or more series of impulses to se-Y lect a group of lines and means automatically responsive to cause the switch to select an idle line of the selected group where the selected ffroup requires more than one series of impulses and responsive to an impulse of a second impulse series irrespective of the number ot' impulses in the latter series to cause the switch to select an idle line of a group selected b one impulse series.

7. In a teleplione system, an automatic 'switch having normally ellective and normally ineffective Wiper sets respectively, a

lurality of levels of contacts each level having contacts accessible to only one of said wiper sets, other levels of contacts each having a contact available to both wiper sets and means for reversing the status of said wiper sets automatically after the selection of the level.

8. In a telephone system, an automatic switch of the two directional type, a plurality of wiper sets, lines terminating at said contacts, directive controlled means for elevating one of said wiper sets opposite one group of said contacts and for simultaneously moving the other wiper set opposite a second grou of contacts, means for causing said switc to move both vwiper sets to select an idle line of a group and automatic means effective after the directive movement for determining which Wiper set will be used.

9. In a telephone system. an automatic switch of the two directional type, a plurality of wiper sets, a bank of contacts divided into a plurality of groups, lines terminating at that contact, directive controlled means for elevatin one of said wiper of said directive controlled means for desets opposite one group o said contacts and termining which wiper set will be used. for simultaneously moving the other wiper In witness whereof, I hereunto subscribe 10 set opposite e second grou of contacts, my name this 31st day of August, A. D.,

l means for causing said switc to move both 1925.

wi. r sets to select an idle line of a. group, an automatic means effective independent RUDOLPH F. STEHLIK.

6 I 1,ess,s1s

trolled means for elevatin one of said wiper of said directive controlled means for desets opposxte one group o said contacts and termining which wiper set will be used. for slmultaneously movIng the other wiper In witness whereof, I hereunto subscribe 10 set opposite a second grou of contacts, my name this 31st day of August, A. D., l means for causing said sWItc to move both 1925.

wier sets to' select an idle line of a group, an automatic means effective independent RUDOLPH F. STEHLIK..

CERTIFICATE oE CORRECTION.

Patent No. 1,638,513. Granted August 9, 1927, to

RUDOLPH F. STEHLIK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page S, strike out lines 114 t0 130, and page 6, lines l to 9, comprising claims 8 and 9, and insert the following as claims 8 and 9:-

8. In a telephone system, an automatic switch having two wiper sets, means for moving said wiper sets simultaneously, a plurality of levels of contacts available to both wiper sets but available to one wiper set before any level becomes available to the other wiper set, and another plurality of levels of contacts available only to one of said wiper sets.

9. In a telephone system, a connector switch, groups of lines terminating in bank contacts of said switch, said switch responsive to one or more series of impulses to select a group of lines, means automatically7 effective after a group has been selected by more than one series of impulses for causing it to automatically initiate its line selecting movement, means for preventing the initiation of the line selecting movement where the group is selected by one impulse series, and impulse controlled means for causing the line selecting movement to be initiated in the latter instance.;`

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day' of June, A. D. 1928.

. M. J. Moore, (Seal) Acting Commissioner of Patents.

CERTIFICATE 0F CORRECTION.

Patent No. 1,638,513. Granted August 9, 1927, t0

RUDOLPH F. STEHLIK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 5, strike out lines 114 to 130, and page 6, lines 1 to 9, comprising claims 8 and 9, and insert the following as claims 8 and 9:-

8. In a telephone system, an automatic switch having two wiper sets, means for moving said wiper sets simultaneously, a plurality of levels of contacts available to both wiper sets but available to one wiper set before any level becomes available to the other wiper set, and another plurality of levels of contacts available only to one of said wiper sets.

9. In a telephone system,V a connector switch, groups of lines terminating in bank contacts of said switch, said switch responsive to one or more series of impulses to select a group of lines, means automatically effective after a group has been selected by more than one series of impulses for causing it to automatically initiate its line selecting movement, means for preventing the initiation of the line selecting movement where tbe group is selected by one impulse series, and impulse controlled means for causing the line selecting movement to be initiated in the latter instance.;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of June, A. D. 1928.

M. J. Moore, (Seal) Acting Commissioner of Patents.

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