US1528343A

US1528343A - Automatic telephone system

Info

Publication number: US1528343A
Application number: US352391A
Authority: US
Inventors: Rodney G Richardson
Original assignee: Automatic Electric Co
Current assignee: Automatic Electric Co
Priority date: 1920-01-19
Filing date: 1920-01-19
Publication date: 1925-03-03
Anticipated expiration: 1942-03-03

Description

' Mar. 3, 1925.

R. G. RICHARDSON AUTOMATIC TELEPHONE; SYSflEll 'H'ndnegllfimhardsu h z Filed Jan. 19, 1 92o a Q I Mar. 3, 1925. 1,528,343

R. G.'RICHARDSON AUTOMATIC TELEPHONE SYSTEII Original ilaim. 19,1920 3 sne tssneet z Man-'3, 1925; 1,528,343

R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM,

Original Filed Ja 19. 1920 s-sha e ts snaet a [J/er Bio ck I Ha 025g fizlimhardgbn;

Patented Mar. 3, 1925.

UNITED STATES RODNEY 'e. RICHARDSON, or CHICAGO,

ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY, OLE CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed January 19, 1920, Serial No. 352,391.

I '0 all whom it 972 e 21 concern:

Be it known that I, RODNEY G. RIOHARD- son, a citizen of the United States of America, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to automatic telephone systems, but is concerned more particularly with automatic party line telephone systems in Which means is provided at the exchange for selectively signalling the different stations on a party line; and the object of the invention is to provide a more efficient and flexible system of this kind than has hitherto been available.

Numerous methods of selectively ringing automatic party lines have been devised before this. A system in wide use, which is disclosed in the United States patent to Goodrum, No. 1,156,475, involves the provision of different frequencies of ringing current at the exchange and tuned bells at the subscribers stations. Each party line is accessible to a plurality of groups of connectors, the connectors of each group being adapted to use a different frequency of ringing current to signal on a called line. The group of connectors used in any case, and therefore the station signalled, is determined by the number called. Other systems, employing so called frequency selecting connectors, have been devised, in which but a single group of connectors has access to any given line, each connector of the group being provided with means responsive to a digit in the called number for selecting the proper frequency of ringing current.

In all these systems, the stations on each party line are definitely and permanently associated with a particular series of call numbers, and there is no practicable or feasible way by which the individual call numbers maybe variably associated with the. different party line stations. Efforts have been made in the past to remedy the inherent defects in these rigid grouping systems by employing an intermediate distributing frame for connecting up the party lines, and with considerable success. The

Renewed July 14, .1924.

application of Owens, et al, Serial N0.143,- 657, filed Jan. 22, 1917, and my pending application, Serial No. 177,653, filed June 29, 1917, disclose improved selective ringing systems in which each party line is accessible for purposes of being called by way of as many branches as there are stations on the line, and an intermediate dis- 'tributing frame is provided at which each party line may be connected at will to desired plurality of said branches, which any branch may be shifted at will to any party line. Means is thus provided whereby a subscriber may be changed to another party line without changing his call number; and these systems also effect an economy in the central office switching mechanism by eliminating dead numbers and by permitting the load to be distributed more advantageously.

The fact remains, however, that even in these latter systems a given call number, while it may be changed from one party line to another, is nevertheless permanently associated with a certain particular frequency of ringing current and therefore one of the most desirable ends, that ofutilizing the outside cable plantt-o its full capacity, is not attained. For example, in changing a subscriber from one party line to another, he must necessarily be connected to a line on which a vacancy exists corresponding to the frequency of his call num ber, and if there is no such vacancy in that locality, a new line must be started, even though there may be many lines having vacancies which correspond to other frequencies. It follows that in a working telephone system of this character there will be numerous party lines which are not filled to full capacity, and the consequent ineflicient utilization of the cable plant is a serious defect.

My invention overcomes all these objections, and provides a selective ringing system which not only is a considerable improvement on prior systems when considered any simply as a selective ringing system alone; but which has all the advantages of the sys tems referred to previously, with the additional advantage that it permits all vacancies on party lines to be filled up without regard to frequencies, and thus secures full and at economy in the use of the cable plant. I accomplish these results by the use of an in termediate distributing frame and fre quency selecting connectors in which, however, the various frequencies are not permanently associated with particular call numbers. On the contrary, the relation between the frequencies and call numbers may be varied at will and is determined by the manner in which the called line branches are connected at the intermediate distributing frame. In calling a party line number, the desired frequency is not selected by any particular digit in the number, but by the entire number as a unit and the actual physical selection does not take place until after the connector has been operated, when the proper frequency of ringing current is automatically selected andaconnected to the called line. As stated, the call numbers are not permanently associated with particular frequencies, but any call number may be associated with any frequency; and the frequency of the ringer of any station on a arty line may be changed without changthe call number.

Having stated in more or less general terms the object and scope of the invention, the apparatus and circuits used to carry out the same will now be explained more in detail, referencebeing had to the accompanying drawings, comprising Figs. 1, 2 and 3, which are circuit diagrams showing the essential features of a telephone system embodying the invention.

Referring to the drawings. the substation A, Fig. 1, is an ordinary automatic substation, which, although shown for convenience as being individual to the line, may equally well be a party line substation. It comprises the usual talking equipment and ringer, and also a calling device indicated by the reference character S, through the medium of which the subscriber controls the central oflice switches.

The line conductors 11 and 12 extend to the exchange where they terminate in the rotary line switch O in a manner more clearly shown in Fig. 3 in the case of a called line. The line switch C may be briefly described as a rotary line switch whose movable terminals or wipers have no normal position and which have movement in a forward direction only. The construction of a line switch of this type is well known in the art. A plurality of these individual line switches may be given access to a group of trunk lines extending to first selector switches. One of the trunk lines to which the line switch has access is shown in the drawings as extended to the first selector D, which is a vertical and rotary selector switch of the usual construction. The selector D, together with a plurality of similar selectors, has access to a plurality of groups of trunk lines, the trunk lines of each group terminating in a group of connector switches. One of the trunk lines to which the selector D has access is shown extending to the connector E, Fig. 2. The connector E likewise is a Vertical and rotary switch of well known construction, and, except for the circuits having to do with the selective ringing, is of the usual type which is in common use. It is understood that second and third selectors may be used if desired according to the capacity of the exchange; and it may be stated that the system of trunking employed is the same as the system commonly referred to as the percentage trunking system.

in Fig. 3 I have shown in detail the manner in which a party line is connected for both incoming and outgoing service at the main and intermediate distributing frames. The layout shown may be described briefly as follows: The four party line comprising conductors 201 and 202, which has the four substations A to A inclusive, connected in bridge thereof, is assumed to enter the exchange by way of cable pair B which is terminated on the cable side of the main distributing frame in the usual manner. This cable pair is connected by means of a jumper with any desired pair on the switchboard side of the main distributing frame, as for example, pair 1. All the terminal sets on the switchboard side of the main frame are connected by means of-cables with correspondingly numbered terminal sets on the vertical side of the intermediate distributing frame. The line switch cables which extend to the individual line switches are connected in multiple with these cables and may be terminated on the switchboard side of the main distributing frame as shown, or on the vertical side of the intermediate distributing frame, it is immaterial which. The jumper on the main distributing frame having been run it will be evident that the party line shown will be connected for outgoing service by way of the individual line switch O, which has access to a plurality of first selectors similar to the first selector D. The line is connected for incoming service at the intermediate distributing frame. On the horizontal side of this frame are terminated the normal cables coming from all the connector groups in the exchange. These cable pairs are preferably arranged in consecutive order on the horizontal side of the frame inaccordance with the call numbers, and the terminal sets should be so numbered. This is shown clearly in the drawing wherein the first set of bank contacts in each of the first four levels of the connector E are connected by conductors with terminal sets 111, 121, 131 and 141, respectively. There is also provided on the vertical side of the intermediate frame a series l Oil of so called idler blocks, the terminal sets on which are arranged in groups of five each, each group being wired as shown in the drawing. The upper set in each group is preferably numbered in accordance with the number of the group according to any desired numbering scheme, while the other four sets of each group are preferably marked in accordance with the tour ditlerent frequencies of ringing current. The manner of connecting the line for incoming service will now be apparent. Terminal set 1 on the vertical side of the intermediate frame is connected by means 01"? the triplex juniper 204 with the upper terminal set of some vacant group on the idler blocks, group 1, for instance. Then the other tour terminal sets oi the group are connected by means of

jumpers

205, 206, 207, and 208 with the terminal sets on the horizontal side of the intermediate frame which correspond to the call numbers which have been assigned to the different stations on the party line. It is to be clearly understood that any call numbers whatever may be used. The line is now completely connected for both incoming and outgoing service.

I will now describe the operation of the circuits involved with the special object of explaining the method by which the stations on a line are selectively signaled. For this purpose it will first be assumed that the subscriber at substation A desires to call the subscriber at substation A, whose ringer will be assumed to be tuned to the 16-cycle frequency, and whose telephone number, therefore, when the line is connected as shown in the drawing, will be 111. When the receiver is removed from the hook at substation A, a circuit is completed over the line conductors 11 and 12 for the line relay 14 of the line switch C. Upon energizing, the line relay completes a circuitextending through the switching relay 13 and the stepping magnet 15 in series at its armature 20, and at its armature 19 connects the test wiper 26 to the above circuit at a point midway between the switching relay and the said stepping magnet. The operation now depends upon whether the test contact with which the test wiper 26 is in engagement is busy or is not busy, If this test contact is busy it will have a ground potential upon it, the switching relay 13 will be short circuited, and the stepping magnet 15, which interrupts its own circuit, will be operated as a buzzer to advance the switch wipers 27, inclusive, step by step in search of an idle trunk line. This operation will continue as long as the test wiper 26 engages grounded or busy test contacts. However, we may assume that in the present case when the call is initiated, the selector D is idle and the test contact 31 therefore is not grounded. Under these circu1nstances, when the line relay 1th is energized. the switching relay 13 is energized immediately afterwardswith the result that the line conductors 11 and 12 are disconnected from the winding of the line relay 14 and from ground, respectively, and are extended by means of armatures 16 and 18,

wipers

25 and 2?, bank contacts and 32, and armatures 63 and and their resting contacts to the upper and lower windings ot the line relay 50 of selector D.

Immediately upon the extension of the line above described the line relay 50 will be energized over the line circuit and will close the circuit of the slow acting release relay 51. Upon energizing, relay 51 prepares the circuits of the selector for the vertical operation in the usual manner, and at armature 58 completes a holding circuit extending back to the line switch C over the following path: ground at G working contact of armature 58 and the said armature, conductor 90, test contact 31, test Wiper 26, armature 17 and its working contact, winding of the switching relay 13, and the winding of the stepping magnet 15 to battery.

acting relay 52 and the vertical magnet 56 in series to battery. By the operation of the vertical magnet the selector shaft is raised step by step until the wipers -72, inclusive, stand opposite the desired level of bank contacts. The slow acting relay 52 is energized in series with the vertical magnet, retaining its armature attracted throughout the vertical movement, of the switch, and upon the closure of the vertical off normal springs 62 completesa circuit for the ste ping relay 53. Upon energizing, relay 53 prepares a circuit for the rotary magnet 54 at armature 60, and at armature 61 establishes a locking circuit for itself. At the end of the vertical operation of the switch the slow-acting relay 52 is deenergized and closes the circuit of the rotary magnet, which is thereupon energized to advance the wipers 70-72, inclusive, into engagement with the first set of bank contacts in the level opposite which they were raised. The rotary magnet also breaks the circuit of the stepping relay 53, which accordingly is deenergized to break the circuit of the rotary magnet, which thereupon deenergizes also and again closes its interrupter contact.

it is understood that the above circuit is The operation now depends upon whether. the test contact with which the test wiper 71 is in engagement is or is' not busy. If thistest contact is busy it will have a ground potential upon it, and the stepping relay 53 will be energized again over a circuit which extends from the grounded test contact, by way of the test wiper 71, armature 64 and its resting contact, the interrupter contact of the rotary magnet, the off normal springs 62, and the winding of the stepping relay 53 to battery. The stepping relay will therefore again close the circuit of the rotary magnet 54, which will operate to advance the-switch wipers into engagement with the nextvset of bank contacts. This operation by which the stepping relay and the rotary magnet are alternately energized and deenergized will continue as long as the test wiper 71 engages busy or grounded test contacts. In the present case it will be assumed that the trunk line shown in the drawings. is the first idle trunk line, and when, therefore, the test wiper 71 arrives at test contact 74 and the rotary magnet, is deenergized, the stepping relay 53 will not again be energized; but instead the switching relay 55, which hitherto hasbeen short circuited, will be operated by current flowing over the following path:

Grounded conductor 90, winding of the switching relay 55, interrupter contact of the rotary magnet, 01f normal springs 62, and the winding of the stepping relay 53 to battery.

Owing to the high resistance of the switching relay 55, the stepping relay 53 is not operated; Upon energizing, relay 55 disconnects-the incoming line conductors from the windings of the line relay 50, and extends them by way of armatures 63 and 65 and their working contacts, wipers and 72, bank contacts 73 and 75,

conductors

76 and 78, and normally closed contacts of the back bridge relay 100 to the upper and lower windings of the line relay 101. of the con.- nector E, Fig. 2.

The calling line having been extended to the connector E, the line relay 101 is energized over the line circuit and completes a circuit for the slow acting release relay 102. Upon energizing, relay 102pre-pares the circuits of the connector for operationin its vertical movement, and also closes a holding circuit extending back: to the selector D, which may be traced as follows:

Ground at G working contact of arma ture 116 and said armature, conductor 77, test contact 74, test wiper 71,, and armature 6 1 and its working contact, to conductor 90, where it joins the previously described holding circuit extending bacl: to the line switch C.

WVhen, the calling subscriber operates his calling device in accordance with the next contact, oli, normal springs 150 and 152,.

winding of the slow acting relay 103, and the winding of the vertical magnet 111 to battery.

This is the circuit over which the first impulse is transn'iitted. At the first upward step of the switch shaft, however, the 011 normal springs are shifted, and the circuit extends from the working contact of. armature 117 by way of off normal contact.

springs 150 and 151, armature 118 and its working conta'it (relay 103 being now energized), winding of; relay 103, and the winding of the vertical magnet- 111 to bat:- te-ry. By the operation of the vertical magnetv 111 the switch shaft is raised step: by step until the wipers 16 O163, inclusive, stand opposite the desired level of bank contacts. Atthe end of'the vertical movement of the switch the slo.wacting relay 103 is,

deenergized and preparestheswitch for operation, in its rotary movement.

The calling subscriber may now operate his calling device in accordance with the last digit in' the number, thereby producing as before a series of interruptions in the circuit of, the line relay 101. At each. re sulting deenergization the line relay now sends a current impulse through the rotary magnet 113 over the following. circuit:

Ground at Gf, armature 115 and its rest-- ing contact, armature 117 and its working contact, o-tf: normal springs 150 and 151, armature 118 and its resting contact, resting contact of armature 124- and the said armature, resting contact of armature 135 and the said armature, and the winding of the rotary magnet 113 to battery.

In response to these impulses the rotary magnet operates to rotate the wipers 160- 163, inclusive, into engagement with the desired set of bank contacts in the level. op.- posite which they were'raisedL Since, in the present case, the desired station is #111, the wipers will have been raised opposite the first level, and they will be rotated into engagement with the first set of contacts in this level, or contacts indicated by reference characters 171,172 and 173. The slow-acting relay 106 isenergized in parallel with the rotary magnet and retains its armatures attracted throughout the rotary movement of the switch. At armature 128 relay 106 connects the test wiper 161 to the winding of the busy test relay 105 and at its. armature 129 relay 10.6 closes a shunt around armature 12a oil the test relay and its resting contact to guard against the possibility of the said test relay being momentarily energized while the test wiper 161 is passing over busy test contacts. It the called line is busy when the test wiper 161 arrives at the test contact associatet therewith, as, for example, the test contact 172, the test relay 105 will be energized, and when the slow-acting relay 106 deenergizes the said relay 105 will remain locked up over a circuit which includes its armature 123. The test relay also opens the rotary magnet circuit at armature 1241 in order to prevent the switch wipers being rotated oil the busyline accidental manipulation of the calling dial, at

armatures

122 and 125 opens circuits having to do with the selective ringing which will be explained later, and at armature 126 connects a lead from the busy signaling machine Q to the lower line conductor. This operation gives the calling subscriber an audible busy signal in the usual manner and he will understand that the desired line is for the time being inaccessible and will replace his receiver.

Let it be assumed, however, that the called line is idle when the connector E is operated as before explained, to establish connection therewith. Under these circumstances when the switch wipers 160163, inclusive, are brought to rest in engagement with bank contacts 171-173, inclusive, the test relay 105 will not be energized, tor the test con tact 172 will not be grounded; and when the slow-acting relay 106 deenergizes, upon the cessation of the rotary movement, the following circuit will be completed:

Ground G at line switch C, Fig. 3, resting contact of armature 1S and the said armature, conductor 213, conductor 21 1, and a strand of the triplex jumper 20-1 to the lower terminal in the upper terminal set of the first group of idler blocks, whence the circuit continues by way 01 resistance 210, the lower terminal of the 16-cycle set, a strand of jumper 205, the lower terminal of the set numbered 111 on the horizontal side of the I. D. F, conductor 215, bank contact 173, wiper 163, armature 121, and its rest ing contact, armature 136 and its resting contact, resting contact or armature 125 and the said armature, armature 130 and its resting contact, lower winding ot relay 109 and the lower winding of relay 1.10 to battery.

It should be noted at this time that upon the deenergization of relay 106 relay 108 is connected to the upper line wiper 160 the same way as relay 109 is connected to the lower line wiper 163, and a branch of the circuit traced above will extend from a point midway between relays 109 and 110 by way of the lower winding of relay 108, to the upper conductor of the called line circuit, and thence by way of the line relay 14 of line switch C, to battery. The lower windings of relays 108, 109 and 110 are so proportioned, however, that the current flow over this branch is insuflicient to operate either relay 108 or the line relay of the line switch C. The lower windings 0t relays 108 and 109 may be of 500 ohms resistance each, while the lower winding of relay 110 may be of 100 ohms, and with these values, it the line relay has a resistance of 500 ohms, less than one tenth of the total current will flow over the branch circuit. Ordinarily this will cause no trouble and the circuit arrangement shown is one which I prefer. However, in case the line relays in any particular system are extremely sensitive, relay 110 of the connector may have .two lower windings instead of one, and thus entirely separate the circuits of relays 108 and 109. To continue with the operation, when the circuit is closed through the lower windings oft relays 109 and 110 in series, relay 109 is energized, but relay 110, being a marginal relay, does not energize on account of the resistance 210 which is included in the circuit, and which may have a value of about 1000 ohms. Upon energizing, relay 109 establishes a locking circuit for itself at its armature 1 17, connects up the 16-cycle ringcurrent generator at its armature 143, closes a contact in the circuit of the ring cut oil relay 104 at armature 141, and at armature completes a circuit for the switching relay 107 as follows:

Ground at G armature 116 and its right hand working contact, conductor 159, armature 142 and its working contact, upper winding of relay 107, test wiper 161, test contact 172, conductor 216, middle terminal of terminal set numbered 111, strand of jumper 205, middle terminal of the 16-cycle terminal set on the idler block, middle terminal of the terminal set numbered 1 onthe vertical side of the 1. D. F., conductor 217, conductor 218, winding of switching relay 3 and the winding of the steppingmagnet 15 to battery.

Upon the closure of the above circuit relay 107 of the connector and the switching relay 13 of the line switch C are energized in series, the latter relay being operated only about half way, due to the fact that the line relay 11 is not energized, with the result that the conductors 213 and 219 are disconnected from ground G and from the line relay 1 1', respectively. When the relay 107 at the connector energizes, it opens the r0- tary magnet circuit at its armature 135, establishes a locking circuit for itself at its armature 134-, connects the grounded conductor 159 to the test wiper 16.1 at armature 188, and closes the ringing circuit at armatures 182 and 136, relays 108 and 109 being disconnected from the line wipers at the resting contacts of these two latter armatures. The ringing circuit over which alternating current from the 16-cycle generator flows out over the lower line conductor, through bridged ringers at the four substations in parallel, and back over the upper line conductor and through the upper winding of the ring cut off relay 104, is the usual ringing circuit, and since it is well understood it will not be traced out in detail. The

ringer at substation A which is tuned to the in operated position short circuits the resistance 210, thereby cutting the said resistance out of the line circuit.

When the called subscriber at substation A. removes his receiver in response to the ringing of his bell, the cut off relay 104: is energized, either by current trom the gen orator or by direct current :t'rom the battery associated therewith, and upon attracting its armature 120 establishes a locking circuit for itself by way of its lower winding. Relay 10a also disconnects is upper winding and the ringing current generator at armatures 119 and 12.1 and at the working contacts of the same armatures completes the talking circuit by connecting'the incoming line circuit with the

line wipers

160 and 163. The transmitter at the called station is now supplied with current through the windings ot the double wound back bridge relay 1.00 in the usual manner. Upon energizing, relay 100 reverses the direction of current tlow in the calling line, as is the usual custom for the purpose of operating a meter or supervisory mechanism, although no such devices are shown in the present system.

The desired connection has now been established and the subscribers may converse as desired. The complete talking circuit is shown in heavy lines, and, being of the usual character, will not be traced in detail.

lVheu the conversation is finished both subscribers will replace their receivers. VJhen the receiver is replaced at substation A the line relay 101 of the connector is deenergized, followed by the deenergization of the slow-acting release relay 102. Relay 10:2 closes the circuit of the release magnet 112 through the medium of which the con nector E is restored to normal in the usual manner. Belay 102 also breaks the holding circuit extending back to the selector D the selector and line switch to normal position also. It should be noted that when the relay 102 of the connector is deenergized the locking circuit of relay 109 is broken, while the locking circuit of the switching relay 107 is not broken until the connector switch has completely returned to normal position. The locking circuits are arranged in this way so that the line wipers of the connector will be disconnected while they are rotating back over the bank contacts during the release of the switch.

A brief explanation will now be given of the operation of selectively signaling the other stations on the party line. Suppose that the station A is called, the ringer at this station being turned to the i li'l-cycle ringing current, and the telephone nun'iher assigned. being #121. The operation oi? the switches is the same as has already been described except that since the number called is #121, the connector E will establish connection with the called line by way of bani; contacts 17%, 175 and 170. the terminal set on the horizontal side of the l. D. F. which is numbered 121, jumper t 'lltl, and the il -cycle idler block terminal 501'. it the end of the rotary operation of the switch, when the slow-acting relay 106 decneigizes, a circuit is completed tor the relays 109 and 110, which is the same cir cult as was described in the previous case, except that it does not include the resistance 210. It follows that since the resist ance 210 is not included in the circuit, the marginal relay 1.10 at the connector will be energized at the same time that relay .09 is energized. Relay 110 establishes a locking circun for itself at its armature 144, and at its armature 14:6 connects up the 33-cycle ringing" current generator. it will be evident, then. that during the signaling operation 33-cycle ringing current will be transmitted over the called line to actuate the 33-cycle ringer at substation A.

The ringers at substations A and i-r are adapted to respond to ringing current o! 50 and 66 cycles, respectively. It will be observed that there is a reversal in the line connections at the idler blocl-z between the 33 and 50 cycle terminal sets, and it tollows that either telephone number 131 or 1 1 is called the normally grounded side Oil the called line will be connected with by the upper wiper 160 of the connector E, instead of by the lower wiper 163. This causes relay 108 of the connector to become cl'lective to connect up either 50 or ($6 cycle generator depending upon whether the relay 110 does or does not energize. The energizetion of this relay, ot' course, depends on whether resistance 210 is or is not included. in the circuit, the same as was previously explained,

From the foregoing considerations it will lill) be clear that the selective'ringing iscontrolled entirely by the connections at the idler block and it will be evident that any telephone number may be caused to ring on any desired frequency simply by connecting the jumper to the appropriate idler block terminal. This makes it possible to changesubscribers from one party line to another, and change the ringing frequency of their telephones, if necessary, without changing their telephone numbers.

The selective ringing system herein disclosed may be used for two-party line service if desired. The four-party selective ringing control system is a combination of a line reversal and a resistance system, and it will be obvious that either system may be used separately to control two-party selective ringing. Suppose that it is desired to have twoparty selective ringing controlled by the reversal of the conductors of the called line. In this case it would be only necessary to omit the relay llOat the connector If] and the resistance 210 and the relay 2124 at the idler block. Since the line is to be a twoparty line, only three sets of terminals would be used in each idle block group, the ones omitted being the terminal sets which, in the present disclosure, are used for 16 and 50 cycle ringing. In case it is desired to use the resistance method of control. the resistance 210, and relay 212 are retained, together with the terminal sets used for the 16 and 50 cycle ringing; while at the con nector the relay 108 may be omitted. any desired ringing current frequencies may be used for the two-party service, and the modi fications proposed are not restricted in any way to the frequencies mentioned.

The private or individual lines may be connected up also along with the party lines, and this is in fact advisable in order to distribute trafiic evenly. among the different connector groups. In connecting up an individual line no idler block group of terminal sets is used, but the jumper is run directly from the terminal set on the hori- Zontal side of the I. D. F. corresponding to the call; number assigned to the terminal set on the vertical side of the I. D. F. which has been cross connected at the main. dis tributing frame.

I am aware that changes maybe made in the system herein disclosed without departing from the general principles of the invention, and on that account I do not wish to be restricted to the precise forms and modifications herein described; but desire to secure and have protected by Letters Patentall forms of my invention which may hereafter be devised, limited only by the scope of the appended claims:

What I claim is:

1. In an automatic party line telephone system, a frequency selecting connector switch for completing connections to called party lines, frequency selecting mechanism in said switch comprising a plurality of relays, and circuit arrangements whereby said mechanism is controlled in its selecting operations exclusively over talking conductors of called lines.

2. In an automatic party line telephone system, a frequency selecting connector switch for completing connections to called party lines, frequency selecting mechanism in said switch, and circuits including talking conductors of said called lines for controlling said mechanism.

3. In an automatic party line telephone system, a connector switch for completing connections to four party telephone lines, a plurality of branches for each line over which connection thereto may be completed, and frequency selecting relays in said switch controllable over the particular branch of a called line by which connection thereto is completed, for selecting any one of four different ringing current frequencies.

i. In an automatic party line telephone system, a connector switch for completing connect-ions to called party lines, a plurality of branches for each line over which connection thereto may be completed, and frequency selecting relays in said switch controllable over a talking conductor of the particular branch of a called line by which connection thereto is completed.

In an automatic party line telephone system, a connector switch for completing connections to called party lines, a plurality of branches for each line over which con nection thereto may be completed, and a frequency selecting mechanism in said switch comprising marginal and non-marginal relays controllable over the particular branch of a called line by which connection thereto is completed.

6. In a telephone system, a party line, a connector switch having movable line terminals, a plurality of branches of said line accessible to saidterminals, a pair of ringing current selecting relays in said switch, means for operating said switch to connect said terminals with any one of said branches, means for thereafter connecting said relays to the said terminals, respectively, and means establishing characteristic electrical conditions in said branches effective to operate said relays selectively.

7. In a telephone system, a' party line, a connector switch having movable line terminals, a plurality of branches of said line accessible to said terminals, a pair of ringing current selecting relays in said switch, means for operating said switch to connect said terminals with any one of said branches, means for thereafter connecting said relays to the said term1nals,'respectively, means establishing characteristic electrical conditions in said branches effective to operate said relays selectively, another relay for disconnecting both relays of said pair, and a circuit for said other relay closed by whichever relay of said pair that is operated.

8. In a telephone system, aparty line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect a calling line with any one of said branches, and selective ringing equipment in said connector selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on said line.

9. In a telephone system, a tour party .line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect a calling line with any one of said branches, four ringing current generators of different electrical character corresponding to the four stations on said line, and selective mechanism in said connector selectively controlled over the connected branch to select the proper generator to selectively signal a desired station on said line.

10. In a telephone system, a four party line, an automatic connector switch, a plurality'of branches of said line accessible to said switch, means for operating said switch to connect a calling line with any one of said branches, four ringing current generators of diiierent frequency corresponding to the four stations on said line, and selective mechanism in said connector selectively controlled over the connected branch to select the proper generator to selectively signal a desired station on said line.

11. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect a calling line with any one of said branches, and self-locking relays in said switch selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on said line.

12. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect with any one of said branches, ringing current generators of different electrical character, and mechanism individual to said connector selectively controlled over a talking conductor of the connected branch to select the proper generator to selectively signal a desired station on said line.

13. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect with any one of said branches, ringing current generators of different frequency, and mechanism individual to said connector selectively controlled over a talking conductor of the connected branch to select the proper generator to selectively signal a desired station on said line.

14. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect with any one of said branches, and relays in said switch selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on said line.

15. In a telephone system, a calling and a called party line, an automatic connector switch, a plurality of branches of the called line accessible to said switch, means whereby a subscriber on the calling line can operate said switch to connect his line with any one oi said branches, and selective ringing equipment individual to said connector selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on the called line.

16. In a telephone system, a calling and a called party line, an automatic connector switch, a plurality of branches of the called line accessible to said switch, means whereby a subscriber on the calling line can operate said switch to connect his line with any one of said branches, ringing current generators of different electrical character, and mechanism individual to said connector selectively controlled over a talking conductor of the connected branch to select the proper generator to selectively signal a desired station on the called line.

17. In a telephone system, a calling and a called party line, an automatic connector switch, a plurality of branches of the called line accessible to said switch, means whereby a subscriber on the calling line can operate said switch to connect his line with any one of said branches, ringing current generators of different frequency, and mechanism individual to said connector selectively controlled over a talking conductor of the connected branch to select the proper generator to selectively signal a desired station on the called line.

18. In a telephone system, a calling and a called party line, an automatic connector switch, a plurality of branches of the called line accessible to said switch, means whereby a subscriber on the calling line can operate said switch to connect his line with any one of said branches, and relays in said switch selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on the called line.

19. In a telephone-system, a party line having two branches, a connector switch and means for operating the same to connect with either of said branches, and a pair of ringing current selecting relays in said switch controllable over said branches, re spectively.

20. I11 a telephone system, a party line having two branches, a connector switch and means for operating-the same to connect with either of said branches, a pair of ringing current selector relays in said switch, and a normal connection from one side of said line to ground for operating said relays, there being a reversal in the line conductors of one of said branches, whereby each relay is operated only when a particular branch is connected with.

21. In a telephone system, a party line having two branches, aconnector switch and means for operating the same to connect with either of said branches, a resistance in a talking conductor of one of said branches, and a marginal ringing current selecting relay in said connector not operable over the talking conductor of the branch containing said resistance but operable over a talking conductor of the other branch.

22. In a telephone system, a party line, frequency selecting connector switches, and a plurality of branches of said line accessi ble to said switches, one of said branches having itsline conductors reversed for controlling the frequency selection.

28. In a telephone system, a party line, frequency selecting connector switches, a plurality of branches of said line accessible to said switches, and a resistance in one of the talking conductors of one of said branches for controlling the frequency selection.

24. In a telephone system, a party line, frequency selecting connector switches, a plurality of branches of said line accessible to said switches, two of said branches having their line conductors reversed, and a resistance in a line conductor of a reversed branch and also in a conductor of a non-reversed branch, the said reversals and resistance being effective to control the frequency selection in any connector which is operated to connect with said line. 1

2-5. In a telephone system, a party line, frequency selecting connector switches, a plurality of branches ofsaid line accessible to said switches, a resistance in one of the line conductors of one of said branches for controlling the frequency selection, and means for short-circuiting said resistance after the frequency selecting operation is completed.

26. In a telephone system, a party line, frequency selecting connector switches, a plurality of branches of said line accessible to said switches, each branch comprising talking conductors and. a third conductor local to the exchange, a resistance in one of the line conductors of one of said branches for controlling the frequency selection, and a relay energized over the third conductor of said branch for short-circuiting said resistance. 1

27. In a telephone system, a party line, connections normally existing from the two talking conductors of said line to the opposite poles or the exchange battery, respectively, a plurality ofbranches of said line, a connector switch operable to connect with said line via any one of said branches, and ringing current selecting relays in said switch controlled by current flow from said battery over a talking conductor of the branch by which the connection is estab lished.

28. In a telephone system, a party line, connections normally existing from the two talking conductors of said line to the opposite poles of theexchange battery, respec tively, a plurality of branches of said line, a connector switch operable to connect with said line via any one of said branches, one of said branches having a reversal in its talking conductors, and ringing current selecting relays in said switch controlled by current flow from said battery over a talking conductor of'the branch by which the connection is established. 7

29. In a telephone system, a party line, connections normally existing from the two conductors of said line to the opposite poles of the exchange battery, respectively, a plurality of branches of said line, a connector switch operable to connect with said line via any one of said branches, two of said branches having reversals in their talking conductors, a resistance included in a line conductor of one of the reversed branches and also in a line conductor of one of the branches which is not reversed, and ringing current selecting relays in said switch controlled by current flow from said battery over the branch by which the connection is established.

30. In a telephone system, a party line,

connections normally existing from the two 1 conductors of said line to the opposite poles of the exchange battery, respectively, a plu rality of branches of said line, a connector switch operable to connect with said line via any one of said branches, a resistance in one of the talking conductors of one of said branches, and a ringing current selecting relay in said switch controlled by current flow from said battery over a talking conductor of the branch by which the connection is established.

81. In a telephone system, party lines, groups of automatic connector switches, a separate series of party line branches accossible to the switches in each of said groups,

means for variably connecting each party hne with any desired plurahty 0t said branches, and ringing mechanism in each groups oi automatic connector switches, a.

separate series of party line branches accessible to the switches in each of said groups, means for variably connecting each party line with any desired plurality of said branches, and ringing mechanism in each connector switch selectively controllable over a talking conductor of any branch with whichconnection is established.

In a telephone system, party lines, groups of automatic connector switches, a series of party line branches accessible to each group of conne tors, a distributing frame whereat each pa line is connected indiscriminately with any plurality of said branches, and ringing mechanism in each connector selectively controllable over any branch with which connection is established.

34-. In a telephone system, party lines, automatic connector switches, a series of party line branches accessible to said connectors, a distributing frame whereat each party line is connected with a plurality of said branches, and ringing mechanism in each connector selectively controllable over a talking conductor of any branch with which connection is-established.

In a telephone system, a party telephone line incoming to the exchange, a calling branch for said line terminating in an automatic switch, as many called line branches for said line as there are stations on the line, connector switches having access to said called line branches, means in each connector controllable over talking conductors of the several called line branches of said party line for selectively signaling any station thereon, and a distributing frame on which the said line and its called line branches are connected by means of jumpers.

36. In an automatic party line telephone system, a connector switch for completing connections to called party-lines, a plurality of branches for each line over which connection thereto may be completed, fre quency selecting relays in said switch controllable over a talking conductor of the particular branch of a called line by which connection thereto is completed, and an intermediate distributing frame whereat each party line and its several branches are temporarily connected by means of jumpers.

37. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect with any one of said branches, selective ringing equipment in said connector selectively controlled over a talking conductor of the connected branch to selectively signal a desired station on said line, and an intermediate distributing frame whereat the said line and its branches are temporarily connected by means of jumpers.

38. In a telephone system, a party line, an automatic connector switch, a plurality of branches of said line accessible to said switch, means for operating said switch to connect with any one of said branches, ringing current generators of different frequency, mechanism in said connector selectively controlled over a talking conductor of the connected branch to select the proper generator to selectively signal a desired station on said line, and an intermediate distributing 't'ranle where-at the said line audits branches are temporarily connected by means of jumpers.

89. In a telephone system, a party line having two branches, a connector switch and means "for operating the same to connect with either of said branches, a pair of ringing current selecting relays in said switch controllable over said branches, respectively, andv an intermediate distributing frame whereat the said line and its branches are temporarily connected by means of jumpers.

4:0. In a telephone system, a party line, frequency selecting connector switches, a plurality of branches of said line accessible to said switches, one of said branches having a reversal in its line conductors for controlling the frequency selection, and an intermediate distributing frame whereat the said line and its branches are temporarily connected by means of jumpers.

41. In a telephone system, a party line, frequency selectingconnector switches, a plurality of branches of said lineaccessible to said switches, a resistance in one of the talking conductors of one of said branches for controlling the frequency selection, and an intermediate distributing frame whereat the said line and its branches are temporarily connected bymeans of jumpers.

42. In a party line telephone system, an intermediate distributing frame, connector banks and party lines connected to terminal sets on opposite sides of said frame, other terminal sets on said frame arranged in groups of fire, a jumper running from one termina set of each group to one of said party line terminal sets, four jumpers running from the remaining sets ot each group to four connector bank terminal sets, and permanent multiple connections between the five terminal sets of each of said groups.

cs. In a party line telephone system, an intermediate distributing frame, connector banks and party lines connected to terminal terminal sets, other jumpers connecting theremaining terminal sets of each group with a plurality of connector bank terminal sets, and multiple line connections between the terminal sets of each of said groups, there being a reversal in the multiple connections between two sets of each group.

n. In a party line telephone system, an intermediate distributing frame, connector banks and party lines connected to terminal sets on opposite sides of said frame, other terminal sets on said frame divided into groups, a jumper connecting one terminal set of each group with one of said party line terminal sets, other jumpers connecting the remaining terminal sets of each group with a pluralityv of connector bank termina sets, multiple line connections between the terminal sets of each of said groups, and a resistance included in one of said multiple line connections between two sets of each group.

45. In an automatic telephone system, a plurality of four party lines each terminating in an automatic switch, said switches being operable to extend outgoing calls from said lines, means for distributing incoming cals to the stations on said lines comprising a plurality of groups of connector switches and a plurality of groups of called line branches accessible thereto, a distributing frame whereat each party line may be connected with any four of said called line branches, and means in each of said connectors for selectively signalling all the different stations which correspond to the called line branches to which it has access.

46. In a telephone system, a subscribers line having an individual line switch at the exchange, one conductor of said line being normally connected to ground at said switch, an automatic connector switch and means for operating it to connect with said line as a called line, a ringing relay in said connector for signalling the called subscriber, a second relay for energizing said ring ing relay, a circuit for said second relay including the said ground connection at the individual switch of the called line, and means in the connector for closing said circuit when the called line is connected with.

17. In a telephone system, a subscribers line having an individual line switch at the exchange, one conductor of said line being normally connected to ground at said switch, an automatic connector switch haviug a pair of line wipers, means for operating said switch to connect said wipers with the said line as a called line, a ringing current selecting relay, a circuit for said relay completed when the ca led line is connected with, said circuit including one of the said line wipers and the ground connection at the said individual switch, a ringing relay for applying the selected ringing current to the called line, and a circuit for said ringing relay closed by said selecting relay.

48. In a telephone system, a subscribers line having an individual line switch at the exchange, one conductor of said line being normally connected to ground at said switch, an automatic connector switch having a pair of line wipers, means for operating said switch to connect said wipers with the said line as a called. line, a ringing current selecting relay, a circuit for said relay completed when the called line is connected with, said circuit including one of the said line wipers and the ground connection at the said individual switch, a ringing relay for applying the selected ringing current to the called line, a circuit for said ringing relay closed by said selecting relay, and circuits for locking both the selecting relay and the ringing relay in energized position until the connection is released.

d9. In a telephone system, a subscribers line, an automatic connector switch, a pair of normal conductors connected with the two talking conductors of said line and accessible to said switch, means for operating said switch to connect with said line as a called line, a ringing relay in said switch for signalling the called subscriber, and circuit arrangements whereby the energization of said relay is dependent upon the continuity of one of said normal conductors.

30. In a telephone system, a subscribers line, an automatic connector switch, a pair of normal conductors connected with the two talking conductors of said line and accessible to said switch, means for operating said switch to connect with said line as a called line, a relay in said switch energized over one of said normal conductors when the said line is connected with, a ringing relay in said switch for signalling the called subscriber, and a circuit for said ringing relay closed by said first relay,

51. in a telephone system, a subscribers line, an automatic connector switch, a pair of normal conductors connected with the two talking conductors of said line and accessible to said switch, means for operating said switch to connect with said line as a called line, a relay in said switch energized over one oi said normal conductors when the said line is connected with, a private normal conductor for said line, a ringing re ay in said switch for signalling the called subscriber, and a circuit for said ringing relay including said private normal conductor and contacts of said first relay.

52. In a telephone system, a subscribers line, an automatic connector switch, a pair of normal conductors connected with the two talking conductors of said line and aceessi-lfe to said switch, means for operating; said switch f0 connect with said line as am called line, a ringing relay in said switch for signalling the called subscriber, a second. relay in said switch for controlling the energization of said ringing relay, and a circuit for said second relay including one of said normal conductors.

Signed by me at Chicago, Illinois, this 14th day or January, 1920.

RODNEY (l. RICHARDSON.