US1456507A - Tandem allotting system - Google Patents

Description

May 29, 1923.

AQE. LUNDELL TANDEM ALLOTTING SYSTEM /M Ven/0f v Awe/4f wia/@l ffy.

May 29, 1923.

A. E. LUNDELL TANDEM ALLOTTING SYSTEM Flltd May 2l 1919 2 Sheets-Sheet f3 m59@ Sn Ltoz Inu( l. DE o w Sum,

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vnarran stares ears-ttt @..LFFHCEG ALBEN E. LUNDJELL, 0F NEW YORK, NPY., ASSIGNOR T0 WESTERN ELECTRIC COMPANY, ENCUEPOEATEDOF NEW YORK, Y., A CDRPOBATION 0F NEW YORK.

. msnm enterarme 'srs'.rnra.

To all whom t may concern;

Be it known that 5I, ALBEN E. LUNDELL, a citizen v-of the United States, residing at New York, in the countyof Bronx and State of New York, have invented certain'new and useful Improvements in Tandem Allotting Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone 'exchange systems and more partlcularly to the distribution of apparatus in such systems.

In telephone systems employing the inder 1switches it has been customary to provide an allctting switch for each roup of line iinders, the function of this al otting switch being to repare a finder switch for operation, anclp as soon as such allotted finder switch is taken for use to hunt out another idle finder switch and prepare .it for operation. A defect of this arrangement is due to the fact that the group of'finders controlled by an allotter is necessarily small, since, if a large number of switches are controlled by a single allotter, considerable time i might'be needed before the allotter could pick out an idle one in casemany of the intervening switches were busy. uring this time interval it might be possible that several calls would be originated.

If, now, it is desired to utilize a 500 point switch as a line finder, and distribution is to be on a 10% basis, 50 line finders would have to be provided to serve this group. The allotter would then have to hunt over a possible contacts and might frequently have to pass over la considerable number before finding an idle one. The time required for this would be, as pointed out above, an undesirable feature.

It is the object of this invention to provide an arrangement in which a large number of finder switches are commonly available to the subscribers of a group and in which there is'never more than one finder in a position tovbe started at" any given time. The object of the invention has been set forth in connection with linelinder switches and the following specification will explain the operation of a system. embodying this type .of switch, but it is obvious that the principle involved is capable of adaptation to la large variety of switches whose functions may be of various characters. The ineppncmon mee may a1, una.v serial no. aeaseo. i

vention is, therefore, not to be restricted except as to the subject matter set forth in the claims.

Acfeature of the invention is the sionJ of' a tandem arrangement of a' lotter switches, there being `a central, or master allotter switch, as it will be termed hereinafter, which is individual to a main group of line nders. ln addition to this master allotter switch therel will be an allotter switch individual to each smaller group of nders into which the main group is divided. The arrangement is such that the allotting of anygivenvinder is the result ofthe joint operation of the master allotter and the allotter individual to some one of the smaller groups.

An additional feature of the invention is an arrangement by which the allotters of the rovismaller groups pre-select an idle finder, so A that as soon as the master allotter moves into connectlongwith this sub-group allotter, the se uence syvitch associated with the finder wi be advanced.

A further featureof the invention resides in the provision of means whereby the master allotterwill'notstop when it comes into operative relation with a group allotter in whose group there are no idle finders.

A. still further feature of the invention is provlded by an arrangement such that the master allotter moves from sub-group to sub-group after each allotting operation thus'producmg a system in which every" finder has an equal chance of being brought into use. This proves a decided advantage over ay system in which certain of the devices are brought into use repeatedly while others do relativelylittle work.I i

It is-thought that the inventionk will best be understood from'the following detailed description, reference lbeing had to the accompanying drawings. v

ln the drawings, Fig. 1 .diagrammatically indicates a ymain group of finders, the first finder of the first group being provided with operating circuits, while the other finders have only certain portions of their operating circuits shown. i

vF ig. 2 shows a master allotter individual to the main group, and oup allotters individual to the varlous smjler groups insuch eat group. In Fig. 2 he masterallotter 1s shown at the left-liand portion of they drawing, while the group allotters are provided with designations which will readily identify them. g

If we assume that the switch is of .500line capacity u line finders which will serve this group. These 50 line finders will constitute what p has been termed a great grou The great moves out of position 1 and into group is divided into five sma er groups of 10 line finders each, each one having an allotter associated with it.

The line finder switch shown in Fig. 1 is of the power driven type.vr In practice this switch would be of the multiple brush type havin r five normally inoperative brush sets, one o which is rendered operative as aresult of a brush selecting operation. Since, however, the invention is not concerned withany particular ty e of switch, it has been assumed that the ine finder shown is provided -with only one brush set which is arranged to be advanced in a continuous mo.

tion over the entire group-of 500 terminals.

IThe mechanical constructlon of such a switch will be entirely obvious to one skilled in the art when considered in connection with the circuit to be described. In order to prevent the disclosure from becoming unnecessarily complicated, it has vbeen assumed that the line finder is directly connected to a connector switch which will make connection to a called subscriber. Thisl switch lhas been shown vas being a step-by-step switch, and may be of anyone .of several well-known types of two motion step-by-step automatic switches. A switch of this ty e is shown in Patent No. 1,252,420'to O. F. 1 orsberg. The allotter switches are all of similar construction and may referably be of a mechanicalf structure simi ar to that shown in Patent No. 1,127,808, issued to E. B. Craft and J. N. Reynolds. The invention is, however, obviously not limited to the employment of an alotting switch of this type.

The operation of the system is as follows: When the subscriber at substation 1 removes his receiver from the switchhook, a circuitvis completed from grounded battery, left-hand winding' of line relay 2, outer amature and back contactl of cutofil rela 3, over the loop of the callin subscribers ine, inner armature and bac contact of rela 3 right-hand winding of relay 2 to groun :A ine relay 2 energizes and `completes a circuit from grounded battery, power magnet of 'se uence switch 4, which, it must be understoo ,'was rplaced into position 1 in readiness for ioperation, upper contact of sequence switch ,spring 5, left-hand armature and front con- /tact of relay 2 to ground. Sequence switch 4 under the control of its master contact 6j position 2. In position 2 of sequence switc 4, a cir-l cuit is completed from grounded battery, winding of up-drive magnet 7, armature and we may then assume that there are `ergized in this circuit, rela back contact of test relay 8,,contact of ses quence switch `spring 9 to ground. The finder brushes 10, 11, 12 are moved upwardl over the terminal bank in search of the cal 1r`1lg line under the control of magnet 7. l hen the test brush 10 engages the test contact of the calling line, a circuit is completed from grounded battery, right-hand armature and front contact of relay 2, resistance 14,test brush 10 and its associated contact, lower contact of sequence switch spring 13, winding of relay 8 to ground. Irlparal e1 a circuit is com leted from grounded battery', winding o cut-'off relay .3 to ground as described. Relays 3 and 8 are en- 8 at its armature opening' the driving circuit of magnet 7, thus bringing the brush set to rest upon the desired terminal. Cut-ofi` rela 3 upon energizaton removes the control o the calling subscribers line relay in the well-known manner, and provides a holding circuit for relay 8. Relay 8 is marginal and will not operate while test brush 10 is passing over the terminals of non-calling or busy lines. If these' lines are busy as calling Qlines, a shunting `ground, is provided by way of re'- sistance 15 of the finder associated with .such other line to prevent the operation of calling, the resistance of cut-off relay3 is sufficient to' prevent the operation of line' 10o' relay 8, it being necessary-that battery he supplied both through the winding of relay 3 and through resistance '14 in parallel in orderthat relay 8 ma, be energized. The current flowing throug relay"3 is not lsufii- 105 cient to cause the actuation of relay 8, but is sufficient to maintain this relay energized after it has been actuated. v

The energization of relay 8 also completes y a circuit from grounded battery, power magnet of sequence switch 4, armature and front contact of relay 8, contact of sequence switch spring 9 to ground, for moving this se-l quence switch out of position 2 and into po- 1 sition 3. Whenseuence switch 4 reaches4 115vv position 2%, a groun ed shunt path is placed` on the test terminal of the calling line to prevent, its seizure by other hunting line finders. In position 3 of sequence switch4, the subscribers line is connected to thestepbylstep connector by way of sequence switch springs 17 and 18.`

A circuit' is now completed from grounded battery, left-hand winding of line relay 19. over the upperv side ofthe line to the calling substation, thence by way of the4 lower side of the line and right-hand wind-l ing of relay 19 `to ground. -Relay 19 is' energized and comdpletes a circuit from ground-v ed battery, win ing of slow-release relay 20,

f y menacer armature and front contact of relay 19 to ground. Relay 20 is energized in vthis l, circuit.

The calling subscriber now operates his impulse sending mechanism 21 to send the rst digit of the calling subscribers num# ber; Since the finder is directly connected to a 100'point connector switch, it will only be necessary for him to dial the tens and units digits. In response tothe operation of the dial, the line circuit is intermittently interrupted, causing in turn the intermittent operation of relay 19. yUpon the first deenergization of relay 19, a circuit is comtion of the armature of relay 19, a circuit is group step.

completed from grounded battery, winding of primary stepping magnet 24, lower contact. of sequence switch spring 25, armature and front Contact of relay 20, armature and back contact of relay 19 to ground. YUpon each energization of magnet 24, the brushl shaft of .the connectorswitch is advanced a Upon the termination of this series of impulses, relay 19 remains energized for a relatively lon period, causing the deenergization of re ay 22. Relay 22 upon deenergization completes a circuit from grounded battery, power magnet of sequence switch 4,

' upper-contact of sequence switch spring 23,

armature and back contact 'of relay 22 to ground for moving this sequence switch out of position 4 and into position 5.

The subscriber now sends the units series of impulses; As before, the first deenrgization-of relay 19 causes the energization of relay 22. Relay 22 attracts its armature and advances. the sequence switch into position 6 over a circuit identical with that for moving sequence switch 4 from position 3 to position 4. Each retraction of the armature of relay 19 also completes a circuit from' grounded battery, winding of secondary stepping magnet 26, upper contact of sequence switch spring 25, armature and front contact of relay 20, armature and back contact of relay 19 to ground. Upon each energization of magnet 26 the'brushes 27 28 and 29 are advanced over a set of terminals in the selected group. Upon the completionotl the sending of the second series of impulses, relay 19 remains energized,

' causing the deenergization of relay 22, which completes a circuit removing sequence switch 4 out ofposition 6 and into position 7. i

Assuming that the called subscribers line is idle, ar circuit is completed as soon as sequence switch 4 reaches position 7 extending from grounded battery, power magnet of sequence switch 4, lower contact of sequence switch spring 36, left-hand armature and back Contact of relay 33,`tovground, for moving the sequence switch'out of position 7 and intro position 8.

In pos1tion 8 guarding potential is applied to the test terminal of the called line by way of sequence switch spring 37 and resistance 16. At Vthe same time ringing current is supplied to the called sub-station from a source of alternating current, winding of relay 38, contact of. sequence switch spring 39, brush 27, over the upper side ofthe called line, through the sub-station apparatus, including the bells and condenser, over the lower side of the line, brush 28, contact of sequence spring 40, to ground. When the called subscriber removes ,his receiver, the

current flow through relay 38 is increased sufficiently to allow this relay to attract its armature, thus completing a circuit from grounded battery, power magnet of sequence switch 4, upper right-hand contact of sequence switch spring 41, armature and front contact of relay 38, to ground, for moving this sequence switch out of position 8 and into position 9.

Position 9 is the talking position and the calling line is connected to the called line by way of sequence switch springs 30 and 31.v During conversation, battery is supplied'to 'thecalled line through the windings of a resistance 32. After conversation is completed the calling subscriber replaces `his receiver on'the switchhook, causing the deenergization of relay19 which, in turn, causes the'release of relay 20. A circuit is now completed from grounded battery, power -magnet of sequence switch 4, lower contact of sequence switch spring 41, armatures and back contacts of relays 20 and 19, to ground, for moving the sequence switch out of position 9 and into position 10.

In position 10 a circuit is completed from grounded battery, winding of down-drive magnet 42,. contact of sequence lswitch spring 43, `to ground. Under the control of magnet 42 the finder brush set is returned to its normal iposition.` When the commutator brush 44.v p mounted on the `brush carriage, engages the `normal commutator segment 45, which occurs when the switch is fully'restored, a circuit -is completed from grounded` battery, power magnet of sequence switch 4,

upper left-hand contact of sequence switch spring 41, segment 45, brush 44, to ground, for moving the sequence switch out of posilower contact, whereupon a,- circlt is com- A pleted from grounded battery, winding of. power magnetof sequence switch 4, lower left-hand Contact of sequence switch spring 23, lower contact of off-normalspring 47, contact of sequence switch springI 48,to ground, for moving the sequence-switch 4 out of Vposition 11 and into position 18. The sequence switch remains in position 18 until the finder is reallotted for service.

Assuming now that at the time the lbrushes 27, 28 and 29 were placed on the terby way of sequence switch spring 37 and' resistance 16 of the connector whichv has previously seized such line, provided that the line is busy as a called line. v'as acalling line, the Aground for energizing relay 33 will be supplied from the test brush -1 by way of the upper contact of sequence switch spring 13 and resistance 15 associline, Relay 33 upon energization locks up through its inner right-hand armature until sequence switch 4 leaves position 9. As soon as relay. 33 is energized, a circuit is completed for supplying busy tone to the calling subscribers line. This circuit extends from ground through the secondary winding of an induction coil, the primary circuit of which includes an interrupting device and battery, through the outer right-hand armature of relay 33 and thenceover the lower talking conductor, through the calling sub-station apparatus, over the upper side of the line and through the left-hand winding of relay 19, to grounded battery. This tone will inform thecalling subscriber that,the desired line is busy.l l

Relay 33, at its' left-hand armature, co pletes a circuit from grounded battery, power magnet of sequence switch 4, upper v,right contact of sequence switch spring 36, left-hand armature and front contact of rclay 33, to ground, for moving) this sequence switch through positions 7, 8 and 9 and into d) i *I y ,y e incassa position v10, whereupon the down-drive niagated with the finder which has selzed the finders will be inf some net becomes efective vand the release of the finder and connector take place aspreviously described. l i The operation fthe allotting system will now be described. Itwas assumed that at the time the calling subscriber at sub-station l'initiated a call, the sequence'switch'of the first finder was in ositionl. t this time the allotter of the u rst group will also be` in position 1/and the master allotter will' be in .position 1. 1

After the finder istakenfor use and its associated sequence switch moves out of position 1,ta circuit will ,be completed for advancing the master allotter when sequence switch y4 reaches position 1%. This circuit conductor 102,5lower contact `o sequence switch. spring 50, to ground. The master allotteru moves from positionq 1 to po'. sition 2 under the control of its normal controlling spring 103. The master allotter will come to rest in position 2 provided that there is an idle finder in the second group;

It all the finders `in the -second Lgroup are busy, a circuit will be completed from`` Iground battery, power magnet of master allotter 100, the upper right-han contactV of allotter'spring 101, conductor 104, through the contacts7105, 106, 107, 108, etc., of the finders of the second group, to ground. In response to the completion of this circuit the master allotter moves on to position 3, at which time it will extend the control 'circuit to contacts controlled by the allotter individual to the third group. c Y

When the finder whose operation has just been describe-.1, reaches position 2, a circuit is completed frpm grounded battery, power magnet of allotter 200, which is individual to the first group of finders, upperleft-hand contact of allotter spring 201, conductor 202, contact of sequence switch spring 51, to

ground, for movingthis allotter out ofposition 1 in search 61:' another idle finder. The allotter 200 will rotate until a' Iinde'r whose sequence switch is standing in position 18, is found, due to the fact that the circuit Aof the upper magnet of allotter 200 is com leted by way of a sequence switch springslmilar to sequence swltch spring 51 on allbusy finders, since'the sequence switches of busy u Jposition included in the positions 2 to 17.

As soon as allotter 200 finds a finder whose sequence switch is in position 18, the allotter comes to rest and the controlfcircuit b way of conductor 203 is extended to' such nder. The allotter v200 cannot, however, move this sequence switch to a position wherein the finder may be! started, since the control cir-` iso rasato? cuit by way of conductor 203 is not completed until the master allotter arrives in position 1.

All ofthe group allotters operate as has just been described for allotter 200, that is, they prcselect or preallot a finder which is in position to be started and, as soon as the control circuit is extended to them in response to the operation of the master allotter, the control circuit becomes effective to advance such preallotted nder into position to be started. l

For instance, when the first finder of the first grou is in readiness-tor.reallotment, that is, wlien its sequence switch is in position 18, allotter 200 may preallot this iinder by stopping in position 1.

The finder sequence switch will not be advanced, however, until master allotter 100 reaches position 1, at which time a circuit will be completed from grounded battery, power magnet of sequence switch et, lower contact ot' sequence switch spring 5, conductor 70, upper left-hand .contact of sequence switch spring 204:, conductor 203, upper left-hand contact of master allotter spring 109 to ground, for moving sequence switch i out of position 18 and into position 1.

From the fore oing it will appear that the following desirale results are obtained from a system of this character, due to the fact that each one ot the five group allotters is a preallotting switch. Any time that there is an available finder switch it can be moved into position to be started as the result of a maximum movement of ive steps of the master allotting switch, since if all the finders in the tour groups are busy, they will be passed over one by one, as a result of a single step ot the master allotter and then the preallotted finder in the fifth group will he seized. ln this way a large number of finders may be allotted in an extremely short space of time.

What is claimed is:

l. ln an automatic telephone exchange system, a main group of automatic switches, said main group of automatic switches being divided intov sub-groups, an allotter switch individual to said main group of automatic switches, an allotter switch individual to each of said sub-groups, means to determine which of said switches shall be taken for use as a result of thecooperation of said main,

'said main grou of automatic switches being divided into su -groups, a control switch individual to said main group of automatic switches, a control switch individual to each of said sub-groups, means to control certain operations of said automatic switches as the result of the cooperation of said main group 'control switch and one of said sub-group master control switch, a plurality of automatic switches, a controlling circuit for operating said automatic switches, means responsive to the operation of said control switches for preparing a portion of said controlling circuit, means including said master control switch to render said controlling circuit effective andmeans to advance said master control switch each time that a controlling circuit is made effective.

4. lin an automatic telephone exchange system, a plurality of group allottcr switches, a master allotter switch, automatic switches controlled hy said allottcr switches and arranged in groups, means to operate said group allotter switches to pre- 'allot an automatic 'switch in each group when there is a switch in such group in condition for allotment, means under the control of said master allotter to render said pre-allotment eective to put an automatic switch into use. means to advance said master allotter into cooperative relation with the group allotter of a new group each time that a switch is taken for use, and means to bring said master allotter to rest in cooperative relation with a group allotter only when there is a switch in such group available for use.,

5. lin an automatic telephone exchange system, a plurality of group allotter switches, a master allotter switch, automatic switches controlled by said allotter switches and arranged in groups, lmeans to o crate said group allotter switches to preal ot an automatic switch in each group, means under the control of said master allotter to render said preallotment eective to put an automatic switch into use, and means to advance said master allotter into coo erative relation with the group allotter o a new group each time that a switch is taken for use.

6. lin an automatic telephone exchange system, a main group of automatic switches, said main group of automatic switches being divided into suboups, a control switch individual to said main group of automatic switches, a control switch individual to each sub-group of automatic switches, means to control certain operations ot said automatic switches as the result of the co-operation of said main group 'iid system, a plurality of control switches, a

conti'ol switch and one of said sub-group control switches, and means to advance said main group control switch into cooperative relation with the control switch of a new sub-group each time that an. automatic switch reaches a cert-ain stage of operation. 7. Inf' an automatic telephone exchange system, a main group of automatic switches, said main group of automatlc switches being divided into sub-groups, a control switch individual to said main group of automatic switches, a control switch individual to each sub-group of automatic switches, means to control certain operations of said automat-ic switches as the 'result of the cooperation of said main group control switch and one of said sub-group control switches, means to bring about such cooperation only when there is at least one automatic switch in a sub-group in a certain condition, and means to advance said main oroup control switch each time that a contro of one oisaid automatic switches has been e'ected.

8. ln an automatic telephone exchange system, a plurality of control switches, la master control switch, automatic switches controlled by said control switches, controlling circuits for operating' said automatic switches, means under the control of said control switches for preparing portions of said controllin circuits, means under the control of sai 'master control switch to render said controlling circuits successively effective, and meanssto advance said master control switch each time that a controlling circuit is made eilective.

9. In an automatic telephone exchange system, a group of multiple terminals, a group of automatic switches having common access to said multiple terminals, said group of automatic switches being arranged in sub-groups, means to allow one only of said group of automatic switches to be in position to be started at a given time, a control switch individual to said main group of switches, a control switch individual to each sub-group of switches, means under the control of said main group control switch and said sub-group control switches to determine the order in which saidswitches are moved into a position to be started, andv means to advance said main group control switch each time that one of said automatic switches is stanted.

ln witness whereof, l hereunto subscribe my name this 19th day of May, A. D. 1919.

ALBEN lil. LUNDELL.

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