US1612202A - Telephone system - Google Patents

Description

Patented Dec. 28, 1926.

UNITE STATES 'FF iil LOUIS A. MORTIMER, 013 NEW YORK, N. Y., ASSXG-NUR, B IEESNE AS$IGNIVIENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A GORBQRATION OF NEXV YORK.

TELEPHONE App c t on filed Fe ruary 9, 19.3 ia Ne 7 This invention relates to telephone systems and more particularly to a busy test arrangement for straightforward trunking systems in which a smaller number of trunk lines are automatically accessible from a larger number of trunk jacks located at a number of positions in a number of switchboards.

ln systems of this general type, automatically operated switches are usuallyemployed whereby when a connection is desired said switches are automatically operated at the seizure of a jack to hunt for and connect said jack with an idle trunk line. The arrangement ofthe jacks at the diiierent boards may be such that a number or" jacks are multipled from one position to another through a number of boards, and connected to the brushes of an automatically operated step by step switch and so that asubsgroup of such jacks and switches are located at one group of boards while another sub-group of jacks and switches are located at another group of boards, and so that the terminals of all said switches are multipled to a single group of trunks.

An object of this invention is to provide a busy test arrangement whereby if all of the trunks in systems of this type are engaged, a busy indication is established for all of the unused jacks having access to said trunks.

Another object of this invention is to provide a busy test indication in systen'is of this type for all of the unused jacks in all subgroups associated with a single group of trunks when all of said trunks are engaged regardless of the location of the engaged jacks.

To attain these cordance with one and other objects in feature of this invention, there is provided in each trunk hunting switch assigned to serve each set of multiple jacks, a separate terminal bank having terminals corresponding to the individual trunks; these busy terminals are multiplied to the corresponding busy terminals of all other switches in the groups and the brushes of said banks are so arranged that they normally bridge two adjacent terminals. By means of this bridging arrangement, if all trunks are engaged, the brushes ot' the special banks of the engaged switches will forn'i a complete bridge of the multiple leads corresponding to the total numberor trunks.

Another feature of this invention relates to the provision of means including a common relay which is operated when all trunks are engaged and the terminals of the special banks or the switches employed are bridged together, to apply a busy indication for the jacks in the subgroups associated with the singlegroup or trunks.

Another feature ofthe invention relates to the arrangement whereby said busy indications are given only at the unused jacks of said subgroup and whereby the jacks associated witht 1e trunks are out off from said common busy indication and given the usual busy test potential on the sleeve leads.

Another feature of the invention resides in the provision of means whereby said busy indications may be in the form of a potential or a tone, or any other indication on the sleeve leads of the jacks.

Another feature of the invention resides in means whereby the conimon busy condition is removed as soon as one of the trunks become idle, by operating the switch that was engaged from the position it occupied while engaged, so as to cause the continuity of the bridge through terminals of the specialflbanks to be broken, and thus cause the common relay to be deenergized and remove the busy condition from the sleeves of the unused jacks.

Re ferring now to the drawings; the circuit shown in Fig. 1 above the dash-dotted li e i dicate one .1 t es ep y s p s c e of one subgroup having access to a smaller number of trunks and a series of multiple jacks associated with said switch is shown at th posi fln 0i t ffere o d A and 13,, while the portion below this line shows another switch of another sub-group of switches associated with the same number of trunks in thesame manner. The multipling of one of these trunks is shown between these two groups of switches, and a similar arrangement of multiple jacks are shown at positions of boards C and D. Below this switch is shown a relay 50 common to all of these switchesbfor establishing a busy condition in accordance with this invention. Fig. 2 illustrates in a schematic manner, the bridging of the terminals correspondingto all of the trunks when busy.

This invention has been illustrated in cono io Wit a str gh f war t un i g er tom in which the operators at a large numher of switchboards and positions have access to a considerably smaller number of outgoing trunks through step-by-step switches and the busy arrangement has been shown as applying to this arrangement merely to illustrate one of its most useful cmployinents. It should be noted, however, that the system shown is not inflexible but hat any other arrangements may be made with the busy arrangement in accordance with this invention applied thereto. To clearly indicate the arrangement of the switches, two sub-groups of switchboards A and B and C and D have been shown with a jack at each of two positions, at each board, that is, jacks 5 and 6 at board A, jacks 7 and 8 at board B, jacks 9 and 10 at board 0 and jacks 11 and 12 at board D,

he jacks at boards A and B being connected to switch 1 and the jacks at boards C and D being connected to switch 21, while all of the switches are multipled through trunks such as 100.

An arrangement of this sort may be provided with a number of positions at boards A, and B and each position may have, for example, twenty jacks with each jackin one position mult-ipled to a corresponding jack in all other positions and the leads from such jacks connected to a switch such as 1, making a total of twenty switches for these two boards; while in the two boards C and D, the jacks may be arranged in the same manner, that is, twenty jacks in each PO81 tion multipled to twenty switches make a total of 40 switches. These switches may then be associated with twenty trunks multinled thereto. in this manner any operator at any position may make twenty connections through to the twenty trunks or twenty connections may be extended to the twenty trunks from any combination of positions. This arrangement may be carried out still further by duplicating these groups of acks at each position and thus, for example, providing jacks at each position through which access may be had to 100 trunks; Fence, this arrangement is. merely descriptive of systems to which the invention may be applied, that is, no matter how many switches and trunks are arranged at these boards or how many boards are used, this invention provides an all-trunk busy arrangement whereby busy potential may be applied to the sleeves of all jacks not used in extend ing a connection and this invention will now be described by tracing a call for one jack for connection with a trunk and later described llOW the busy arrangement func tions when all trunks are engaged.

. Assuming then that the operator at position 5, for example, has connected her cord circuit, not shown, but which may be of any well known type, to jack 22, a circuit is es tablished from battery, over the sleeve contacts of the plug of this cord circuit and the jack 22 thrcugh the winding of relay 23, make-before-break contacts of relay 23, common lead 24, to ground at the armature and back contact of relay 50. Lead 24- is shown common to all the switches in the two subgroups of switches as shown by the taps from this common lead. This circuit causes the operation of relay 23 which locks up to ground at its left hand armature and front contact, and disconnects the common lead 2% at the make-before-break contact of this relay, for purposes as hereinafter will he described.

lhe operation of relay causes also two circuits to be established, one for relay 25 and another for relay and the stepping magnet 27. As relay 25 is slow to operate, the circuit for relay 26 and operating magnet is the one that operates first and may be traced as follows: battery, winding of mag net 27, armature and back contact thereof, to a common point 28 and from battery through the winding of relay 26 to this com mon point 28, thence through middle right hand armature and front contact of relay 23, left hand armature and back contact of relay 25, the brush of switch 32, terminal 3%, outer right hand armature and front contact of relay 23 to ground. This causes the operation of relay 26 which breaks the circuit for relay 25 and causes the stepping magnet 27 to operate switch 1 and advance its brushes to connect with the terminals of the first trunk in a manner well known in the art.

If it is now assumed that the first trunk is idle, the circuit for relay 26 and stepping magnet 27 will be broken at the terminal 3% and consequently the stepping magnet will not advance the switch brushes any further. The release of relay 26 in this case will close the original circuit for relay 25 which may be traced as follows: battery, winding of relay 25, armature and back contact of relay 26, inner make-before-breal: contact and right hand armature and front contact of relay 23, to ground, causing the relay to operate. The operation of relay now disconnects the brush of switch 2-32 from the circuit for relay 26 and magnet 27 and connects it instead to the ground at the outer right hand armature and front contact of relay L3, thus making the terminal associated with this switch 32 and trunk No. 100 busy to other switches.

On the other hand, if it is asumed that trunk IN O/106 is busy when brush of the switch 32 connects with the corresponding terminal, it will be seen that the ground from relay 23 of the corresponding associated jacks will be connected to maintain relay 26 operated and cause the continued operation of magnet 27 to advance the brushes of the switch to a second trunk.

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The circuit inthis instance might-be traced as follows: from battery. through windings of magnet 27 and relay'26, through 'the'middle right hand armature and front contact of relay 23, left hand armature and back contact of relay 25, brush of the switch 32, multiple lead 35 to the brush ofthe switch corresponding to switch 32 of the switch through which trunk No. has been engaged, and from there through the left hand armature and frontcontact of the relay cor responding to relay 25 to the outer right hand armature and front contact'of the re lay corresponding to relay 23, to ground. in this case therefore, the stepping magnet will have taken two steps and connected the" jack 22 to the terminalsoftrunk No. 101. It should benoted that relay 25 in operating also connects the tip and ring leads from jack 22 at its right hand armatures and front contacts to the brushes of switches 30 and 31 which now are connected with the terminals of the corresponding trunks such as 100 or 101.

The brushes of switch 33 are so shaped that they will bridge two adjacent terminals. llhis is illustrated in Fig. 2 and is an important part of this invention as it will be seen that eventually when all twenty trunks have been engaged by twenty jacks at various positions including any combination of operators and switches as shown diagrammatically in Fig. 2, the brush of each engaged switch 33 will each bridge two adjacent terminals and stand in such a position as to completely bridge all the terminals for all of the said twenty trunks, that is, one switch 33 will bridge terminals corresponding to trunks 100 and 101, while the brush of another switch 33 will bridge terminals corresponding to trunks 101 and 102, etc., so that the last trunk engaged will have the brush of the corresponding switch 33 bridge terminals corresponding to trunks 118 and 119. As the corresponding terminals of all the switches 33 are multipled together and the terminal 38 corresponding to trunk 119 is connected to ground as shown in this Fig. 2, a circuit will therefore be completed from this ground through the terminals of the twenty switches 33 and the multiple leads to a common lead 36 which is connected through the winding of the common relay 50 to battery causing this relay to operate. Relay 50 in operating removes the ground through its armature and back contact and thus prevents not only any further conneo tions to be made through any of the unused jacks and the consequent operation of relay 23 but also connects battery to this common lead 24 so that battery potential will be applied to all sleeves of the unused jacks, ex copt of course, the jacks of the switches such as 100 and nineteen others that are used. That is, the jacks multipled from position to position'as, for example, those associated with jack 22 will have a busy potential on' their slieeves'from the battery of the cord circuit connected to jack '22. It will be seen that'in this manner'all the unused jacks will have a busy potential applied to their sleeves either from the armature of relay 5O or'from the battery of the cordcircuits connected to the multiple jacks used.

If now one ofthe trunksbeconie idle by the IGlIlOVitlOftllG plug from the corre spondingjack, it will benoted that the bridge'con'ipleted through the brushes of the engaged switches 33 will be broken bythe' movement of the brush of the particular disengaged"switch 33 follows: a circuit will be completed torthe stepping-magnet 2'7 of that switclrthrou'gh the middle right hand armature and back' contact of the cor responding relay 23 tothe brush of the switch 33 of this tisengaged switch to the ground in the bridge and thus advance the brushes of this switch one step and break the bridged connection. If the break in the bridged connection occurs at the nineteenth trunk, it is evident that only a single step will be taken by the magnet 27 but if the break occurs at some other trunk, the brushes of this particular switch will be further advanced and intact returned to normal position as the ground for trunk 20 will be supplied through this brush until its return to normal position. If a switch not included in a closed chain circuit becomes idle, then it remains where it is withoutmoving, but if the chain circuit is completed to it before it has again been taken for use, it will return to normal.

It is readily seen then that the busy test arrangement in accordance with this invention may function with any straightforward trunking arrangement in which. switches are employed regardless of the par ticular arrangement of the jacks in the various positions and boards as long as the terminals of the switches 33 are multipled as indicated and the brushes thereof are so constructed as to bridge adjacent terminals.

What is claimed is:

1. In a straightforward trunking system, a plurality of jack terminals, a corresponding number of automatic switches associated therewith, a smaller number of trunks available over said switches, a special bank of terminals in each of said switches, with a terminal representing each trunk, said terminals being multipled from switch to switch and each switch being provided with a brush adapted to bridge two adjacent terminals, and a common busy testing means for establishing a busy condition at all jacks not used when all of said trunks have be come engaged, said means being actuated when the terminals of the special banks oi the switches engaged form a complete bridge through all of the terminals representing said trunks.

2. In a straightforward trunking system, a plurality of jack terminals, automatic switches associated therewith, trunk lines accessible through said switches, a common conductor, means forming part of each switch for completing a connection to ground for said common conductor when all trunks are employed in connections, a relay associated with said common conductor actuated when the ground is connected to said conductor, and means including a busy test conductor connected to a source of busy potential when said relay is operated to establish a busy condition at the jack terminals not employed in the connections.

3. In a trunking system comprising a large number of jack terminals, corresponding switching means and a comparatively smaller number of trunks accessible thereby, each of said switching means including a special switching bank having one terminal representing each trunk, said terminals being multipled from one bank to another, a brush for each of said banks arranged to bridge two adjacent terminals, a ground connected at the last oi said special bank terminals at each of said banks, and a busy testing means actuated when all trunks are engaged and a complete bridge is established at the switches used from a ground at one of the banks through the bridged terminals of the banks of the switches used, for establishing a busy test condition at such jack terminals as are not used in the connections.

In witness whereof, I hereunto subscribe my name this 6th day of February A. D.,

LOUIS A. MORTIMER.

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