US1531220A - Automatic telephone system - Google Patents

Description

March 24. 1925.

1,531,220 w. T. POWELL 7 AUTOMATIC TELEPHONE svsmm Filed Sept. 18 1 22 2 Sheets-Sheet 1 PRIMARY LINE SWITCH.

INVENTOR Q \MNFRED T owa March 24. 1925. I E 1,531,220

.w. T. POWELL wwomnc TELEPHONE SYSTEM- Fild Sept. 18. 1922 2 Sheets-Sheet. 2

om: azcouumnv urns swrrcH.

I v I EVEN SECONDARY um; syHTCH.

LINE FIN-DER.

INVENTOR ATT RNEY wmrmso T. POWELL.

Patented Mar. 24, 1925.

j UNITED STATES PATENT OFFICE.

wmrnnn T. rownmaron EocHEsTEE, NEW .YoEx, essrenon. To THE sTEoMnEEG cAELso'N TELEPHONE MANUFACTfiRING A OORPORATION OF NEW YORK.

COMPANY, or EoorrEsTEE. NEW YORK,

AU 'IOMATIG TELEPHONE SYSTEM.

As iration filed September To all whom it may concern; a

Be it known that- 1, WIrITrRED T. PownLL, a citizen of the United States, residing at Rochester, 'in the county of Monroe and State of New York, have invented certain new and useful'lfnpfrovements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description. a v

ThlS invention relates to telephone sys line switch for each line would seem to be i an unnecessary expense.

v For this reason it has been proposed to employ finder switches,

that is, a non-numerical switch for each trunk circuit which switch operates on the initiation of a call to connect the calling line to an idle trunk. This arrangement, while.

it has the advantage of being much less expensive than the former arrangement is not entirely satisfactory. due to the fact that the calling line isnot alway extended to the idle trunk before the calling subscriber starts to dial the wanted number with the result that the .call is either lostor mutilated.

In accordance with the present invention it is proposed to retain the advantages of both systems and eliminate the disadvant ages of the same by employing line switches which are common to several telephone lines with line" finder switches which are commo to several trunk circuits. c

Other features of this invention will ap pear from the detailed description and appended claims.

In the drawings" Fig. 1 represents four subscribers substations'and the lines extendingjtherefrom to a-line-switch shown at 1t, 1522. Serial at. 588,786.

the lower right hand corner of this figure. It will be noted that the substation circuits of only one telephone line are shown in detail but it will be understood that thesubstation circuits of the other three substatio'ns will beidentical with that shown in the upper left hand corner ofthis figure. In the upper left hand corner of Fig. 2 there is shown the operating circuits of a line finder switch, and in the upper right hand corner of this figure there is shown an odd secondary line switch while in the lower right hand corner there is represented an even secondary line switch. At the extreme right of Fig. 2 there is indicated an impulse relay and a slow releasing relay which relays are located at a numerical switch such as a selector or connector employed in a telephone connection.

For convenience in describing this invention,'the lines of the telephone system are divided into groups of one hundred lines each, which groups are further sub-divided intosub-groups of four lines, each subgroup having a primary line switch for its individual use. It will thus be seen that twenty-five primary switches are provided for each group of one-hundred lines.

By referring to the drawing of Fig. 1 it will be noted that the primaryline switch is provided with five sets of brushes, which are rotatable in the well-known manner to engage any one of ten sets of fixed terminals of the switch. Ten pairs of primary trunks are multiply connected to corresponding fixed'terminals inthe primary line switches of the group, each of these t-Wenty trunks terminates in a. secondary line switch whose brushes have access to ten sets of terminals in which ten secondary trunks terminate. Through the actionof various relays, when two of the four'lines of a subgroup are in use the remaining twolines are connected to the terminals of ten finder switches, these switches are, of the same type as the line switches except that they are provided with twenty-five sets of fixed terminals instead of ten sets of terminals as in the ,case oft-he previously mentioned switches. The brushes of each finder switch are connected to one pair of primary trunks. The method by which one pair of telephone lines of a subgroup are connected to the terminals of the finder switches will be described in the course of this description.

The switches previously referred to may be ofthe type similar to that disclosed in the patent of Clement #1,107,153, patented August 11, 1914, while the switching relays referred to may be of any well known type provided with a plurality of sets of contact springs.

WVith this brief outline of the grouping arrangement of lines and switches and with this brief reference to the equipment used it is believed that the invention will best be understood by describing the method of extending a telephone connection from a call-' ing substation such as A to a numerical switch such as shown at the extreme right of Fig. 2, through which the calling line may be extended to a wanted telephone line.

WVhen the subscriber at A removes his receiver from its switch hook, a circuit is completed for the line relay 5, extending from grounded battery, winding of this relay,contact 6 and armature of relay 7, contact 8 and armature of relay 9, upper back contact and armature of relay 10, over the upper side of the calling line and through the substation circuits in series, inner armature and back contact of relay 10, armature and contact 11 of relay 9, armature and contact 12 of relay 7 to ground. Under the control of this circuit, the line relay is energized and closes an operating circuit for the motor magnet 13 of the line switch extending from grounded battery, winding, back contact and armature of this magnet, right hand armature and front contact of relay 5, back contact 14 and armature of relay 7, test brush 15 to ground over test conductors such as 16 of busy primary trunks.

-As soon as the line relay 5 is operated it closes an energizing circuit from ground, its left hand armature and front contact, lower winding of relay 18 to grounded battery. With relay 18 operated, the lines from substations C and D are extended to the finder switches of this group and a circuit is closed from grounded battery, winding, back contact and armature of motor magnet 13, winding of relay 7, armature and front contact 19 of relay 18, front contact and armature of relay 5 to ground. This circuit, however, is ineffective to operate relay 7 since it is short-circuited by ground through test brush 15 and test conductor 16 of busy trunks. As soon as an idle primary trunk is located, a condition indicated by the ab sence of potential on its test terminal, the operating circuit of the motor magnet 13 is no longer completed, and the short circuit is removed from the winding of relay 7 ermitting it to be operated. With the relay 7 actuated the calling line is extended through contacts 8 and 11 of relay 9, contacts 24 and 25 of relay 7, line switch brushes 20 and 21, conductors 26 and 27 of the selected primary trunk to ground at the upper armature of relay 28 and to grounded battery through armature and contact 29 of relay 28 and winding of relay 30.

The relay 30 is thus energized in this circuit and closes a holding circuit from ground at its right hand armature and front contact, conductors 31 and 16, line switch brush 15, contact 32 and armature of relay 7 to grounded battery through the winding of magnet 13. At this time a locking circuit is completed for relay 18 through its lower winding, contact 19 and armature, conductor 38 and contact 32 in multiple with the holding circuit of relay 7. The line extending from substation B, which is arbitrarily known as an even line, is simultaneously extended with the calling line to the even secondary line switch, over conductors 42 and 43.

As soon as the relay 3(), of Fig. 2, is operated it closes an actuating circuit for the motor magnet 44 of the odd secondary line switch traceable from grounded battery, winding, armature and back contact of this magnet, outer armature and front contact of relay 30, inner lower back contact and armature of relay 28, test brush 45, test terminals such as 46 of busy secondary trunks to ground at the front contacts and armatures of relays such as 47 associated with busy secondary trunks. During the time that the motor magnet 44 is advancing the brushes 45, 48, and 49 over busy trunks, a circuit is closed for the relay 28 from grounded battery, winding, armature, and back contact of motor magnet 44, winding of relay 28, inner front contact, and armature of relay 30 to ground. This circuit ineffective at this time, since the relay 28 is short-cirouited during the time that test brush is encountering busy test terminals. When an idle secondary trunk is located. a condition indicated by the absence of potential on its test terminal, the operating circuit of the motor magnet 44 is interrupted, causing the odd secondary line switch to be stopped with its brushes in engagement with an idle secondary trunk, and the relay 28, which is no longer short circuited, attracts its armatures to extend the calling line conductors 26 and 27, of the primary trunk through the upper front contacts and armatures of relay 28, through the brushes 48 and 49 of the odd secondary line switch and the windings of relay 50 in series to ground and grounded battery respectively. Relay 50 is thus energized and effects the operation of the slow releasing relay 47 which in turn applies ground through its armature and front contact tothe multiple tenninals, such as 46 of the selected secondary trunk circuit. This is effective to complete a 1 holding circuit for the relay 28 extending from test terminal 46 through test brush 45, lower inner armature,- front contact and winding of relay 28, to grounded battery, through the winding ofniotor mag;

' net 44. i

The apparatus is now in condition to receive directive impulses from the calling subscribers dial sender. It is believed that it is unnecessary to describe the operation of setting up the remainder of the connection, but it will be understood that in response to these impulses selector and connector switches of the well known type are directively operated to extend the selected secondary trunk to the terminals of the wantedsubscribers line. As indicating the character of connector circuits which will function with the circuits of Fig. 1 and 2, reference is made to the connector switch circuits of Patent gi -1,382,012, granted to Winfred T. Powell, June 21, 192 1.

M Reference has been made in the description to the fact that the line extending from substation B has been simultaneously extended by the operation of primary line switch of Fig. lytoan even secondary line switch such as that shown in the lower right hand corner of Fig. 2. This'even secondary line switch is ineffective until the subscriber at B initiates a call, when ito-perates to select an idle secondary trunk. If the subscriber at B- initiates a call attliis time, the

relay 51 (Fig. 2) .is'energizedin a circuit which are connected to ground potential,

applied at the front contact and armature of the relay 47. Under the control of this circuit the motor magnet 104 advances the brushes 56, 58 and until an idle secondary trunk is located at which time the motor magnet 104. ceases its'operatio-n and the switching relay 5st is operated as described in connection with the switching relay 28, to extend the conductors 42 and 43 of the selected primary trunk to the conductors of the selected secondary trunk through brushes 58 and 59 of the even secondary line switch.

Let it now be assumed that when either or both of the lines extending from substations A and B are in use in the manner indicated that either or both ofthe lines terminating at substations C and D initiate a call. First consider the method of extending a telephone connection from station C under these conditions. It will be remembered that the operation of the relay 18 in tlie'manner already described has closed contacts as and 35 so that when the subscriber at C initiates a. call, a circuit is closed trom grounded battery, winding of relay 60,, (appearing at the upper-left hand corner oi Fig. 2), armature and contacts 61 ofrelay 62 condiizctor 63, contact 34 and armature of relay l8, conductor 64-, back contact and upper armature of relay 65. over the upper side of the line leading to sub-station C and through the substation circuits at C in series, over the lower side of the calling line, inner armature and back contact of relay 65, conductor 66, armature and contact '85 of relay 18, conductor 67, contact 68 and armature of relay 62 to ground. The relay 60 is thus energized, and closes an operating circuit for the relay 1. relay, lower back contact and armature of relay. 70, conductor 89, right hand armature and contact-o1 relay 60 to ground. Re lay 17 when thus energized closes an operating circuit for the motor magnet 69 of the line finder switch, extending from grounded battery, winding, back contact and armature of magnet '69, .inner armature and front contact of relay 17, cont-act 71 and armature of. relay 72, test brush 7 3. test terminals such as 74, or non-calling lines, continuity spring and back contact of relays similar to 62, armatures and back contacts of relays such as 60 of non-calling'lines to ground. Under the control of this circuit; the motor magnet 69 advances the brushes, 73, 75, 76, '77 and 78 of the line finder switch until testbrush 73' encounters the test terminal of the calling line which is indicated by the absence of ground potential on test teuninal such as 74:, due to the fact that relay 60 associated with the calling line has opened the circuit normally closed to ground through its left hand armature and back contact. During the time that the motor magnet 69 is operating, a circuit 18 also closed from grounded battery, winding, back contact and armature of tins magnet, winding of relay 72 to ground at the left hand front contact and armature of relay 17, but this circuitis ineffective at this time since it is short circnited by the ground applied through the inner front contact and armature of relay 17 hen, however, the test brush 73 locates the calling line this short circuit is opened and the relay is operated over the circuit ust described.

The conductors 63 and 67, are extended through brushes 77 and 780i the line finder and contacts79 and 80 of relay 72 through conductors similar to 81 and 82 of an idle primary trunk and thence to ground at the upper armature and back contact of a relay similar to 28 and to grounded battery. through the winding of a relay similar to 30 at an idle odd secondary line switch. The relay corresponding to 30 is operated to apply a. holding ground over the conductor similar to 31 and conductors similar to 83 and 84, contact 85 and armature of relay 72 through a brush similar to 73, terminal 74, conductor 86, continuity spring and armature of relay 62, winding of this relay to grounded battery. The secondary line switch last selected also operates in the manner already described to select an idle numerical switch which will be directively operated from the dial sender at substation C. It will be noted that while the calling line C is being extended to an idle primary trunk hat the telephone line at substation D is likewise extended through conductors 87 and S8 and brushes similar to 76 and of the mentioned line finder to an idle pri mary trunk leading to an idle even second ary line switch.

It will, of course, be understood that allotting means are provided to assign an idle finder switch for use. Any allotting means may be employed, but in the present disclosure it is deemed advisable to show an extended starter wire arrangement. According to this arrangement as soon as the first line finder switch of the series is taken for use, its relay such as 7 O, is operated so that this starter wire 89 is extendedthrough the conductor 90, thus assigning for use, the next finder switch of the series. When the line switch of Fig. 1 seizes the trunks leading to the secondary line switches of Fig. 2, the relay 70 is operated from grounded battery, its winding, right hand back con tact and armature of relay 17, conductors 83 and 31 to ground at the front contact and armature of relay 30 or 51. In this manner the start wire is eiitended to allot an idle line finder for use.

In the foregoing description it has been seen that when one or both of a pair of telephone lines is calling only the line switch individual to said group of four lines is operated, but it while the line switch is in use one or both of the other pair of lines of the sub-group initiates a call, then a line finder switch comes into use. In practice the lines may be grouped in such a way according to the period of the day in which they are customarily used that the line finder switches will rarely be called into use.

It should be stated that when a line such as that extending from substation A is call ing the slow releasing relay, such as 91, is in series with one side of the line during the connection and it is bridged by a non-inductive resistance. This relay is made slow releasing so that ground potential is main- When the line terminating at substation A is called, a connector seizes this line, a circuit is closed from ground, over conductor 92, armature and back contact of relay 91, winding of relay 10 to grounded battery. The relay 10 attracts its armatures and thereby disconnects this line from the brushes of its line switch to prevent false operation thereof.

At the time of the release of the telephone connection relay 4 7 represented at the extreme right of Fig. 2 releases to remove the holding ground from test terminals 46 and 5'2, this permits relay 28 to release and since this secondary line switch is of the'so-called Stay-put type it remains in the position last used in readiness for extending another call. II at this time the even secondary line switch is not in use, holding ground is re moved at the lowermost armature of relay 28 from holding conductors 81 and 16 which permits the release of relays 7 and 18 of Fig. 1 and since the primary line switch is of the Stay-put type; that is, remains in the position last used, it is in readiness for ex tending other calls.

In the event that both the odd and even secondary line switches of Fig. 2 were in use simultaneously, then holding ground is maintained at the holding conductor 16 of the primary line switch until both of these line switches have been released, in one case the holding ground being maintained at the lowermost armature of the relay 28 and in the other case at the uppermost armature and front contact of relay 54. In the event that the call has been extended through the line finder switch, then when the odd and even secondary line switches have been released in the manner indicated, holding ground is removed from holding conductor 81 and multiple holding conductor 83 so that relays 72 and 62 of the line finder are released, and since the line finder switch is of the type that remains in the position last used this switch is in readiness for extending other telephone calls.

What is claimed is 1 In a telephone system, a plurality of telephone lines divided into groups, each group containing at least two pairs of telephone lines, a line switch having brushes and fixed contacts, trunks terminating in said fixed contacts, the telephone lines of a group being normally related to the brushes of a line switch, means responsive to the initiation of a call on one of a pair of telephone lines for operating said line switch to extend said pair of telephone lines to a pair of idle trunks, and means responsive to such connection for extending the other pair of lines of said group in selective rela: tion to other idle trunks.

'2. In a telephone system, telephtme lines arranged in groups, an individual line switch for each group having movable brushes and fixedcontacts, the telephone lines of a group being normally in selective relation to its individual line switch, line finder switches having fixed terminals and brushes, trunk circuits each terminating in the brushes of a line finder switch and in the fixed contacts of a plurality of line switches, means responsive to the initiation of a call on one of the telephone lines for causing the line switch individual to said group of lines to con-nectcertain of the same to idle trunks, and meansresponsive to such connection for extendi'ngwthe remaining telephone lines'of said group to the fixed terminals of line finder switches.

3. Ina telephone system, telephone lines arranged in groups, line switches having movable brushes and fixed contacts, the telephone lines of a group being, normally in selective relation to the brushes of a line switch, finder switches having fixed terminals and brushes, tr mkcircuits each terminating in the brushes of a line finder switch and in the fixed terminals ofa plurality of line switches, means responsive to the initiation of a call on one of the telephone lines for causing the line switch of said group of lines to connect certain of the same to idle trunks, means responsive to such connection for extending the remaining,telephone lines of said group to the fixed terminals of a group of line finder switches, and means for allotting idle finders for use.

4. In a telephone system, groups of telephone lines, each group having at least two pairs of telephone lines, line switches having movable brushes and fixed contacts, one of said line switches being individual to each group of telephone lines, trunks multiply connected to fixed contacts of said line switches, line finder switches having fixed terminals and movable brushes, a pair of said trunks terminating in the movable brushes of each of said line finder switches, a pair of relays, for each group of telephone lines having contacts through which the lines of its associated group are normally extended to brushes of its individual line switch and having other contacts by which said telephone lines on the energization of saidrelays may be con nected to the terminals of a plurality of said line finder switches, and means responsive to the initiation of a call on one of said telephone lines for extending a pair of lines to idle trunks by way of the individual line switch and for operating one of said pair of relays to extend the other pair of said telephone lines to terminals of said lin finder switches.

5. In a telephone system, a plurality of telephone lines arranged in groups, each group having at least a pair of telephone lines, a plurality of trunks, a line switch individual to each group of telephone lines connectible to said trunks, line finders com mon to a plurality of groups of lines, trunk circuits, and means controlled by the extension of a calling telephone line by way of one of said trunks and the individual line switch of a group for extending certain of the other telephone lines of the group to a line finder switch.

6. In a telephone system, a plurality of telephone lines arranged in groups, each group having at least a pair of telephone lines a plurality of trunks, a line switch in dividual to each group of telephone lines, line finder switches common to a plurality of grou-psof lines, trunk circuits, and means controlled by the condition of the other lines of the group in which a telephone line is located, for determinating whether said individual line switch or one of said line finderswitches is to extend said telephone line when it initiates a call.

7. In a telephone system, a plurality of telephone lines arranged in groups, each group having at least two pairs of telephone lines, line switches having movable brushes and fixed terminals, one of said line switches being individual to a group of telephone lines, the telephone lines of a group being normally extended to its line switch, trunks. means for causing said line switch to extend a pair of lines to a pair of trunks simultaneously, aplurality of line finder switches, each having fixed contacts and movable brushes, :1 pair of said trunks terminating in the movable brushes of a line finder switch, means functioning under certain con ditions to cause an idle line finder switch to extend its pair of trunks to a pair of telephone lines, all of the telephone lines of a group normally having as a first choice their individual line switch if all of the telephone lines of this group are idle, but having one of said line finder switches as a second choice if one of said other telephone lines of this group is in use when it originates a call. I

8. In a telephone system, a plurality of telephone lines divided into groups, each group containing at least two pairs of tele phone lines, a line switch having brushes and fixed contacts, trunks terminating in said fixed contacts, the telephone lines of a group being normally in selective relation to a line switch, means responsive to the initiation of a call on one of a pair of telephone lines for operating said line switch to extend a pair of telephone lines to a pair of idle trunks, and means responsive to such connection for extending the other pair of lines of said group into selective relation to other idle trunks.

9. In a telephone system, a plurality of telephone lines divided into groups, each group containin at least two pairs of telephone lines, a ine switch having brushes and fixed contacts, trunks terminating in said fixed contacts, the telephone lines of a group being normally in selective relation with the movable brushes of a line switch, means responsive to the initiation of ai call on one of a pain'of telephone lines for operating said line switch to extend said pair oi telephone lines to a pair of idle trunks, and common non-numerical switching means responsive to such connection for extending the other pair of lines of said roup in operative relation to other idle trunxs.

10. In a telephone system, a plurality of telephone lines arranged in groups, a line switch individual to each group of telephone lines, a plurality of trunks terminating in said line switches, line finder switches in which said trunks and telephone lines terminate, the line switch of a group being arranged to extend certain of said telephone lines to idle trunks on the initiation of a call on onerot' the lines of a group, and means to assign an idle line finder switch to extend the remaining telephone lines of said group to other idle trunks on the initiation of calls thereon.

11. In a telephone system, a plurality of lineswitches and in the movable elements tacts of one of said relays, means responsive to the initiation of a call on one of the telephone lines of a pair for operating its individual'line switch to extend said pair of telephone lines to a pair of idle trunks,

means responsive to said extension for operating one of the relays of said group for extending the other pair of telephone lines of saidigroup to the contacts of said group of finder switches, and means responsive to the initiation of a call on one of the lines or" said last mentioned pair for extending said pair of telephone lines to a pair of idle trunk circuits through a line finder switch.

12'. In a telephone system, groups of telephone lines, each group having two pairs of telephone lines, two pairs of trunks for the use of the telephone lines of each group, a line switch individual to a group of telephone lines, relays for normally extending both pairs of telephone lines to a pair of idle trunks terminating in said individual line switch, trunk finder switches in which the other pair of trunks terminate, and means efifective on the initiation of a call on one pair of telephone lines for disconnecting the other pair of telephone lines of the group from the trunks extending to said line switchand fol connecting the same to the pair of trunks leading to the line finder switches. is

In witness whereof, I hereunto subscribe my name this 15th day of September, A. D.

WINFRED T. POWELL.

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