US1537326A - Make-busy scheme for telephone systems - Google Patents

Description

my 12, 192s. 1,537,326 B. D. WlLLS MAKE BUSY SCHEME FOR TELEPHONE SYSTEMS Filed Aug; 28, 1,922 h h r@ j j L er1-Land D -l1-M115 Patented May 1,2, 1925.

yUNITED STATES PATisu'r OFFICE.,

BERNARD MAKE-BUSY SCHEME FOR TELEPHONE SYSTEMS.

v'Appueauon` inea August 2s, 1922. serial No. 584,7e1. f

To all 'whom t may concern.'

Re it known that I, Buurman D. `vVinLrs,

a citizen ot the United States oi' America, and a resident of Oak Park, Cook County, and State of Illinois, have invented certain new and useful Improvements in Make-Busy Schemes for Telephone Systems, otn which the following is a specification.y 1 i The present inventiony relates to make busy schemes for telephone systems in general, Vbut is more particularly applicable to make busy schemes for telephone systems in which primary and secondary trunking is used, and the principal object is the production ot' a new and improved arrangement ior making busy alll the idle secondary switches of a group as soon as all the trunks accessible thereto become busy.

So far -as applicant knows, it has been the practice in' primary and secondary trunking systemsto use one chain relay persecondary trunk tor making a secondary-group busy when all the secondary trunks become busy. lWhile this arrangement has proven fairly successful -from an operating,standpoint, it

desirable from an economical Vstandpoint to reduce the equipment and to simplify the arrangement.` llhis is done according to the present invention by providing one relay per group of trunks, which relay is normally short circuited by a ground. potential which is placed on a connnon conductor. by each of the switches to which the trunks accessible to a secondary group extend. This ground potential is removed by the'switches y in succession as they become busy and, when the last switch becomes busy, the shunt 1s linally ren'ioved 'trom `the. common relay,`

whereupon the group is made busy.

A1ccording to another 'jeature ot the invention, the same principle is applied to a secondary group in which partot the trunks are individual to the group and other trunks are common to this group and to as many others asV desired. In this case,fthe group make-busy relay is controlled from the individual trunks and a similar relay is controlled by the common trunks, and therelay of the common group 'maintains the make-busy relay shunted until the last common trunk becomes busy.

Another object is to arrange the selectors which are accessible to the secondary switches so that theycontrol the sliunting ground with the addition of amountr of equipment.V

Referring now to the drawings,V which comprise a single sheet, there is shown a line switch 'C individual to the line of suba minimum station A, and having access to the secondy switch 'D are of the well-known rotary type, in winch the wipers have no normal position. and move m a forward direction only, while the selectors suoli as E are ot' the well-known D. WILLIS, OF OAK PARK, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC i COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. i y

sal

vertical and rotary type, and, accordingly, f

have 100 sets of bank contacts which are arrangedV in ten horizontal rows or levels.

The circuits of the switches C and l) are well-known and likewise thecircuits of the selectors such as E, with the exception of the addition ot the lower contact of oliir1 normal spring 73 andthe associated conductor and the improved make-busy jack il.

Perhaps the apparatus shown vwill be understood better in vconnection with its operation when a call is being through.

Then thereceiver is removed at substation A, a circuit-is closed overline conductors 11 and 12 for line relay 14 of the line switch-C. Relay 14, upon energizing, places ground upon private normal conducto-1' 10 at armature 20, thereby making the calling line busy, and closing circuit for switching relay 13 and stepping magnet 15 in series, and at armature 19 connects test wiper 22 to the junction of switching relay 13 and stepping magnet 15. AIn casethe trunk upon which the wipers are standing is idle, the connecting up ofthe test wiper has no particularifunctionV and switching relay 13 energizes immediately. Assuming the trunk to be busy, however, switching relay 13 is short circuited by the ground ypotential which is presenten the test contact there.- of, and the wipers 21-23, inclusive, are advanced in search of an idle. trunk by the buzextended there-k zer-like action `of stepping magnet 15, which operates through test Wiper 22. llVhen an idle trunk is reached, which trunk it will be assumed is the one extending to the secondary switch D, switching relay 13, being no longer short circuited,energizes in series w ith stepping magnet 15, 4stepping magnet `15 not energizing on account of the high resistance of switching relay 13. Upon energizing, switching relay 13 opens the test circuit and prepares ,the holding circuit at armature 17, and at armatures 16 and 16 disconnects line conductors 11 .and 12 from the Winding of line relay 14 and ground, and extends them by way of wipers 21 and 23, conductors 24.- and 26, and armatures 30 and 33 to the winding ol*l line relay 28 of the secondary switch D and ground, respectively. Line relay Q8, uponenergizing, places ground on release trunk conductor 25 at armature 36, thereby establishing the usual holding circuitfor switching relay 13 of the line switch C before slow acting relay 14 has had time to dcenergize. :is a further result of the energization koli' relay 28, it closes a circuit for switching relay 2,7 and stepping magnet 29 in series at armature 35, and at armature 34 connects test wiper 38 to the junction of the switching relay and the stepping magnet. The secondary switch i) new operates in the `same manner as the line switch C to select an idle trunk, which trunk it will be assumed is the one comprising conductors lO-flQ, inclusive, and extending to the selector E. Switching relay 27, upon energizing, when the idle trunk is reached, extends release trunk conductor 25 through to test Wiper 33 at armature 32; opens the test circuit and prepares the holding circuit for relay 27 at armature 31; and at armatures 30 and 33 disconnects conductors 24e and 26 from the Winding .of line relay 23 and ground, and entends them Vby way yof wipers 37' and 39, conductors 40 and 42, and armatures 8,2 and 85 and their resting contacts to the windings of line relay 65 of selector E. Line relay A65, upon energizing, removes ground at one point from the common lconductor 55, and closes a circuit tor release relay 66 4at armature 76, which .circuit includes armature S-l and its resting contact and the normal contact ot the jack J. Release relay 66, upon energizing, discon- -nects the resting contactof armature 76 from a circuit tor vertical magnet 7 0 by Way ol' armature 78 and its working contactand series relay 67. By the operation oit vertical magnet 70, the switch Wipers 86-88, inclusive, are raised opposite the desired level of bank contacts. Slow acting series relay 67 is maintained energized in series with vertical magnet 70 throughout the vertiral movement and, in conjunction with the oil normal contacts 7l, which close upon the lirst vertical step, closes a circuit for stepping relay 68 by way ot' inter-rupeter contacts 7 5. Stepping relay 68, upon energizing, closes a locking circuit tor itself at armature 8O and at armature 81 prepa-res a circuit for rotary magnet 71.

At the .end ol the Vertical n'iovement, slow acting relay 67 deenergizes and closes the circuit of rotary magnet 71 at armature 79. Rotary magnet 71, upon energizing, advances the wipers 86-88, inclusive, into engagement with the .first set ot bank contacts in the level opposite which they are raised and, near the end ot its stroke, opens the circuit et stepping relay 63. Stepping relay 68, upon deenergizing, opens the circuit oi rotary magnet 71 at armature S1, whereupon rotary magnet Y71 deenergizes and closes its interrupter contacts 75 again. ln case the trunk terminating in the' first set of bank contacts is idle, switching relay 69 energizes in series with stepping relay 68 at this time. lffrssuming the trunk to be busy, however, switching relay 69 is short cir-- cuited and relay o8, upon energizing, closes a circuit jtor rotary magnet 71, whereupon the s'fitch wipers are advanced into engagement with the next set of kbank contacts. This operation continues until an idle trunk is reached, which trunk it will be assumed is the one terminating' in bank contacts 39-91, inclusive, whereupon switching re lay 69, being' no longer short circuited, energizes over the Jfollowing circuit: From ground bywvay o'f the working); contact of armature 77 and said armature, switching relay 69, off normal contacts 7l, interrupter contacts 75, and stepping relay 63 to battery. Stepping relay 68 does not energize at this time, however, owing to the high resistance of switching relay 69, Switching relay 69, upon energizing, disconnects ground 'from armature 76 ot' line relay 65 at armature Si, thereby opening the circuit of release relay 66; opens the test circuit and prepares the holding circuit at armature 83; and at armatures 32 aud 35 disconnects conductors Ll() and 4t2 troni relay 653 and extends them by way ,ot wipers 86 and 83 and bank contacts 89 and 91 to the windings o the line relay of the switch to which the seized trunk extends. Then this occurs, the line and release relays (not shown) of the seized trunk energize, whereupon the latter places ground upon the associated l sition in the usual manner. Then the shaft of the selector E reaches normal position,

release trunk conductor, ythereby establishing the usual holding kcircuit for the switches C, D, and E before the release relay 66'has had timeto deenergize. s

The calling subscriber may now entend the connection on to the desired line ,in the usual manner and, whenV he replaces his receiver at the end of the conversation, ground is removed from the release trunk conductor of the trunk seized bythe selector VE, whereupon the switching relays 1.2i, 27, Yand 69 of the switches C, D, and E, respectively, deenergize.Y Switching relay 69, upon def energizing, closes a circuit for release magnet 72 as follows: from ground by way of the normal contact ofthe jack J, resting contact of armaturefSa and said armature, armature A76 and its resting contact, armature 78 and its resting contact, off normal spring 7 3 and its upper contact, and release magnet 72 to battery. Upon the energization of release magnet 72, the shaft and wipers of the selector E are restored to normal ponet 72k and applies groundto conductor 55.

vThe operation of the make-busy equipment will now be taken up a little more in detail. It was pointed out above that the` Y selector E removes ground vfrom conductor upon being seized, and replaces the ground when it becomes idle and is restored to normal.` Assuming now thatthe ground potential. is removed from conduc tor 55 by all of the selectors, such as E, individual to the group; conductor 55 remains groundedby armature53 of relay 50 which` is associated with the trunks which arev common to several secondary groups.

Assuming further that thel common trunks also become busy, ground isremoved fromV sistance 57 and makes all the idle secondary line switches in the group busy, the trunk extending to the switch D for example, being made busy through the resting 'contact of armature 32 andsaid armature.V

As soon as a trunk becomes available in either the common group or the individual group, the secondary group in question rendered idle again. For example, if one of the selectors such as E places ground on conductor 55, upon being restored to normal, relay 54 is short circuited and deenergizes, or if one of the selectors such as E places ground on conductor L51 of the common group of trunks, relay 50 is short circuited gizes also.

ground on and upon deenergizing, places 54 deeper'- conductor 55, whereupon relay` In case it is desired to make a particular Yswitch which is accessible to a secondary switch busy, 1t is necessary to do two things.

ground from conductor 55 by `the lower spring of the jack J moving out of engagement with its normal contact.

V What is claimed is:

1. n a trunking system, a group of trunks, a l switch having access thereto, a conductor common to said group maintained at a certain potential at each of said trunks, means for taking said trunks for use, means responsive to the takingvfor use of each of said trunks for removing said certain potential from said conductor at one point, and means responsive to the removal of said cer` tain potential at'the last trunk to bevtaken for use for rendering said switch non-selectable. n 2. In a trunking system a lirst group of switches, a lirst group or' trunks accessible thereto, a 'second grouproi" switches, a second group of trunks accessible to both said groups or' switches in common, a lirst and a second conductor common to said first and said second groups of trunks, respectively each of said conductors being maintained at a certain potential byeach ofthe trunksin the grou-p to which it is common, means confA trolled oversaid second conductorfor main-v taining said lirst conductor at said certain potential at still another point, kmeans for taking saidv trunks for use, means respon# sive to the taking for use of each of said trunks for removing said certain potential from the associated common conductor at one point, means'responsive to the removal of said potential from said second conductor at all points for removing said potential from said first conductor at said other point, and means responsive to the removal of said certain potential from said first conductor at all points for rendering'said first group oi" switches non-selectable. v s

3. In a telephone system, a firstgroup of switches, a second group of switches accessible to said first group,feach of the switches in said second group having line, holding, and release relays, and normally closed olf normal contacts, normally closed contacts on each ofsaid relays, a conductor common to 4 Las maintained at a ground potential by each of said switches through said normally closed contacts on each ot the relays named and said ofi normal contacts in series, means for taking each of said switches for use, means effective while one of said switches is in use for removing the ground potential from said common yconductor at that point by main taining ,open one or more of said normally closed contacts, and means .controlled by the remoyalfot said ground potential from said conductor at all points for rendering said first group ot switches non-selectable.

4i. In a trunking systeim a group of trunks, a switch having' access thereto, a conductor common to said group being tained at a certain potential at each of said trunks, means for taking said trunks for use, means responsive to the takingY for use of each of said trunks tor removing said certain potential from said conductor at one point, means responsive to the removal of said certain potential at the last trunk to be taken for use tor rendering said switch non-selectable, a jack for each of said trunks, and means responsive to plugging into one otsaid jacks for rendering the associated trunk nonselectable and tor removing said certain potential from said conduct-or at ,that point, i

5. The combination, with group or' automatic switches, of a guarding circuit includinera relay and a source ot current, a pa.- 4of contacts at each switcn for shortcircniting said relay, and means in each switch :tor opening the associated contacts when the switch is operated.

6. The combination, with two groups of automatic switches, oia a guarding, circuit for ,the lirst group of switches controlled jointly by the switches in the second group, said circuit including` a relay and a source of current, contacts on a switch in the second lgroup vfor maintaining said relay short circuited while the switch is in normal position, and similar contacts on each ot the other switches in the second group. Y

7. 'The combina'tiOn, 4with a group of switches, of a relay, and means for operating said relay only when all said switches are in use, said i'ueans comprising a closed cnciut tor said relay, and means in each switch ell'ective while the switch idle tor maintaining said relay short circuited.

8. ln a telephone system, a group ot' lines, an electro-magnet common to said lines. a circuit tor said magnet including a source ot' current, a pair of contacts individual to each line` circuits over which all said pairs oi contacts are connected in parallel with each other and in shunt of said rela-y, and means for `opening each pair of lcontacts when the associated line is in use. y

9. ln a telephone system, a group Voit lines, an electro-magnet common to `said lines, a circuit Jfor said magnet including a source of current, a pair ci contacts individual to each line, circuits over which all `said pairs of contacts are connected in parallel with each other and in shunt .ot said reay, means for opening each ,pair of ,contat-ts when the associated line is in use, and a. resistance included in said circuit to prevent excessive current How while said magnet is short-circuited.

in a telephone system,A an automa-tic switch, a guarding circuit common to said switch and other similar switches, a line relay in said switch having a pair of contacts, an operating ,circuit Vfor the switch over which said contacts transmit impulses when the switch is in use, and a branch of said guarding .circuit on which said contactg maintain a potential while the switch is idle.

ll. In a telephone system, an automatic switch, a guarding circuit having a branch incoming to said switch, a Vrelease magnet for said switch, a locali switch conductor connected to a source of current, means for connecting said conductor to said magnet to release said switchand vmeans responsive to the restoration of said switch for disconnecting said conductor from said magnet and tor connecting it to the said branch of said guarding circuit.

In witness whereof, I hereunto subscribe myl name this 25th day of August, A. D.. 1922.

BERNARD D. WILLIS.

DISCLAIMER.

1,537,326.-Bcmm"el D. Willis` Oak Park, Ill. MAKE-BUSY SCHEME ron TELEPHONE SYSTEMS. Patent dated May 12, 1925. Disclaimer filed May 20, 1926, by the assignee, Automatic E lcctrz'c Inc.

Hereloy enters a disclaimer Ito. claims 1, 5, 7, 8, and 9 in said specification, which are in the following words, to wit:

l. In a trunking system, a group of trunks, a switch having access thereto, a conductor common to said group maintained at a certain potential at each of said trunks, means for taking said trunks for use, means responsive to the taking for use of each of said trunks for removing said certain potential from said conductor at one point, and means responsive to the removal of said certain potential at the last trunk to b e taken for use for rendering said switch non-selectable.

5. The combination, with a group of automatic switches, of a guarding circuit 'including a relay and a source ot current, a pair of contacts at eac-l1 switch for shortcircuiting said relay, and means in each switch for opening the associated contacts when the switch is operated.

7. The combination, with a group of switches, of a. relay, and meansfor operating said relay only when all said switches are in use, said means comprising a closed circuit for said relay, and means in each switch effective while the switch is idle for maintaining said relay short circuited.

18. In a telephone system, a group of lines, an electro-magnet common to said lines, a circuit for said magnet including a source of current, a pair of contacts individual to each line, circuits over which all said pairs of contacts are connected in parallel with each other and in shunt ot said relay, and means for opening each air of contacts when the associated line is in use.

9. In a telephone system, a group of lines, an electro-,magnet common to said lines, a circuit :tor said magnet including a source of current, a pair of contacts individual to each line, circuits over which all said pairs of contacts are connected in parallel with each other and in shunt of said relay, means for opening each pair of contacts when the associated line is in use, and a resistance included in said circuit to prevent excessive current flow while said magnet is short-circuited.

[,Ojicz'al Gazette June 8, 1926.]

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