US2170429A - Telephone system - Google Patents

Description

Aug. 22, 1939. M. RO SIN TELEPHONE SYSTEM 4 Sheets-Sheet 1 Filed Sept. 27, 1935 INVENTOR N4 wucs X05111 ATTORNEY M. ROSIN TELEPHONE SYSTEM Aug. 22, 1939.

4 Sheets-Sheet 2 Filed Sept. 27, 1935 INVENTOR MIURICE ROSIN ATTORNEY Aug. 22, 1939. M RQSIN 2,170,429

TELEPHONE SYSTEM Filed Sept. 2'7, 1955 4 Sheets-Sheet 3 INVENTOR N17 warez R 0511? ATTORNEY Aug. 22, 1939. M. ROSINY 2,170,429 I TELEPHONE SYSTEM Fi led Sept. 27, 1955 4 Sheets-Sheet 4 ATTORNEY Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE 10 Claims.

This invention relates to improvements in telephone systems and has for its object the provision of exchange apparatus of a new and useful character for separating the establishing func- 5 tions from the holding functions thereof, with a consequent saving in the size, cost and maintenance of the apparatus compared with that used in known systems.

Another object is to provide a telephone system in which the selector switches are released as soon as they have functioned, so that one line selector switch will serve a plurality of incoming circuits.

A further object is to provide a telephone system of great flexibility in which the capacity of the operating apparatus can be easily increased in proportion to the average density of callsper-trunk, rather than in proportion to the total number of connections to be made.

Another advantage is that selectors, connectors, etc., may be simplified into simple types of line switches, since their functions are now reduced to selecting a pair of contacts in accordance with the dialing, then returning again. immediately to normal. I

Other objects will more fully hereinafter appear and the following specification is merely illustrative of the invention and is not limitative thereof. The system, by modifications that are 30 obvious to those skilled in the art, may be used with full automatic, semi-automatic, auto-manual or manually operated systems, and with either panel-rod, all relay, or rotary switch apparatus. As the latter is in extended use, it has been chosen to here illustrate the invention.

In any telephone system, the routine process of establishing a connection between the calling and called line may be divided into:

, (A) The period necessary to establish the 40 connection, which comprises the operation of dialing by the calling subscriber and the operation of the switch mechanism at the exchange or central office to find, connect to and ring the called subscriber.

(B) The period necessary to holding the connection (A) above, while the connected subscribers are talking, and then restoring the central ofiice mechanism to normal.

Heretofore, in most systems, it has been customary to provide each line with a selector or relay which established the connection (through other or trunk switches or relays if necessary) and held the connection while the conversa- 55 tion ensued. This tied up two or more switches for the duration of the conversation.

The present invention, by separating the establishing from the holding functions (as first defined) enables the aforementioned switches to be released and used by other lines as the switches are not tied: up in holding the connections.

This is accomplished by providing means: to permit a plurality of lines to have access to a selector common to all said lines as said switch serves only to establish connections. Apparatus is provided separate from said switch and bypassing the same (but operated thereby) to set up a circuit from the calling to called line which circuit, as soon as established, holds the desired connection during the duration of the conversation, the calling (and any intermediate switches) being released and permitted to function to set up other circuits.

The average time required to establish a connection in known systems is from '7' to 8 seconds but an additional 1 to 2 minutes use of the apparatus is necessary to hold the average connection. The use of the equipment for this additional time is eliminated by the present invention, simple and inexpensive apparatus being used during the holding period, while the connected subscribers are talking.

In the accompanying drawings, where by way of illustration a system employing a well known type of rotary switch is shown:

Figures 1 and 2 are schematic diagrams of a telephone system embodying the invention;

Figures 3, 4 and 5 illustrate the connecting frames or boards used to by-pass the regular line and trunk switches as more fully hereinafter described;

Figure 6 is a diagram illustrating the construction of the locking mechanism, Figure 1; and

Figure '7 is a simplified diagram of the apparatus employed where two lines are connected.

Schematic circuit Figures 1 and 2 The numeral l denotes a subscribers telephone instrument having the usual calling dial II. This is connected via conductors l2 and IS with the central office. The conductors l2 and I3 in the central office connect to a pair of contacts on an ordinary line switch l3a and from there line l2 leads to the movable armature I4 of cut-01f relay IS. The armature M normally rests against a contact which is connected to a common wire C, which may extend to similar contacts on a plurality of cut-off relays, one of which is associated with each incoming subscribers line. The line l3 leads to a conductor and then via conductor 22 to one of the vertical magnets 23 of a connecting or switch frame mechanism Figures 3, 4 and 5 (to be presently described, and which is diagrammatically indicated within the dotted lines 24), via conductor 25 to winding 26b of individual locking magnet 26 (one per line Figure 6), and continues via conductor 52 to armature I5, and via conductor [5a, finally terminating in any suitable form of switch mechanism 2| such as that shown within the dotted line H, wherein for the sake of illustration is shown a selector of the rotary type having associated therewith a contact member 4'! controlled by the wiper 48 of the switch, as hereinafter described.

So far, with exception of relay i6 and its contacts and contact member 41 in the selector, lock; ing magnet 26 and vertical magnet 23, all of the equipment described is found in known automatic telephone exchanges, the connection being made by the selectors |3a and 2| through a pair of conductors l8 to either line switches, trunk switches or the like, in order to connect with another subscribers lineor trunk. No attempt has been made toshow the selector construction in |3a and 2| in detail as any construction can be used with the addition of the member 41 in selector 2| as before-mentioned.

With known equipmenuthe selector 2| is permanently associated with the incoming line and remains so during the conversation. The present invention releases this selector as soon as it has selected the wanted \line, so that it may be used by a plurality of lines,

When subscriber ||l lifts his receiver from the hook, a circuit is completed as follows: from battery l9 through winding 20 of selector mechanism 2| via conductor |5a to armature l5 of cut-off relay |6 one per line), Via conductor 52 to winding 26b of individual locking magnet 26, via conductor 25 to one of the vertical magnets 23 of the connecting or switch frame mechanism 24. From this magnet 23, the circuit continues via con.- ductor 22 to conductor 5| to one of the contacts on line switch |3a via conductor l3 to subscriber I0's instrument and dial associated therewith, via conductor I2 to the opposite contact on line switch I3a, via armature l4, via conductor C to selector 2|.

At the same time a circuit is also completed from conductor 52 through winding 25a of individual locking magnet 26 (one per line), via armature 21 to conductor 28 to common locking magnet 29 (one per switch frame 24) through windings 29a and 30 thereof, via conductor 3| to the bottom contact 32 in selector switch 2| to member 4'! in said switch which is grounded at 33. As soon as this circuit is completed, the vertical magnet 23 on the switch frame 24 operates (as presently described) moving its contact fingers to the position shown in Figure 5B, ready to be operated by the subscribers dialing.

Individual lock magnet 26 also operates pulling upits armature 34 which prevents the dialing from dial going to another free connecting frame connected at 35 (in case frame 24 is busy as presently described). At the same time, the common locking magnet 29 draws up its armatures and locks itself up by reason of current flowing from battery 36 via armature 45 and contact 45 through winding 30 via conductor3| to contact 32 and ground 33. The locking opera tion is now completed and the connecting frame 24 is closed to all other subscribers until the calling subscriber H) has finished dialing the first digit of the number desired, or about 4 seconds time.

When subscriber l0 operates dial I I, the impulses pass over conductors |2 and i3 in. the usual manner, through line switch |3a and into the switching mechanism 2|, operating the latter in the usual manner.

Supposing the selector, in accordance with the dialing, stops on contacts 66 and 1!] on its bank;

circuit is then established as follows: from contact 65 via conductor 66a. to battery 61 via conductor 68 and via armature 69 into lower winding of horizontal magnet 65 via conductor a back to contact 10 on the selector bank. Horizontal magnet 65 now operates, and. rotates horizontal rod 3'! on its own axis, bringing earns 63 and 63 into contact with those vertical contact fingers 4| and 44 facing them on their own level.

Cut-off relay l6 now obtains current over the following circuit: battery 50 via conductor 5| to cam 63, via one of the contact fingers t via conductor 4|] to relay l6, via conductor 39, via conductor 22, via conductor 5| Via one bank contact on line switch |3a via conductor l3 through subscriber l0s instrument, via conductor |2 to op posite bank contact in line switch l3c, via armature l5 via line C terminating in ground of battery l9.

Cut ofi relay I6 now operates, drawing up armatures M and i5, cutting off selector 2| and leaving it free for other calls. Vertical magnet 23 is now also cut off, and drops its rod 38.

The talking circuit is now'as follows: from battery 5|! via conductor 5|, cam 53 to one of the contact fingers 4|, via conductor 40 through cut-off relay l6, via conductor 39, via conductor 22, via conductor 5| through line switch l3a, via conductor |3 through subscriber lfis telephone and dial associated therewith, Via conductor l2 through the opposite bank contact of line switch l3a via armature Hi to contact 42 (which is now closed by relay l6) via conductor 53 to the opposite vertical contact finger 44, via cam 63 to line 52, backto battery 50. Lines 5| and 52 constitute the outgoing lines which are extended Via conductors or trunks H and. 12 to any other board or exchange.

In operating, horizontal magnet 65, besides rotating the horizontal rod 31, as described above, also pushes back with its plunger armature 69 thus placing an. alternate or duplicate horizontal magnet on an associated board into circuit for the next call on this line, if this horizontal rod 3'! is busy. Magnet 65 thus cuts itself off from the battery 61, but at the same time obtainsv talking circuit current through its upper winding from battery 50, having just closed the cam circuit for talking. Selector mechanism. 2| has now been cut out, as explained, by the operation of cut-off relay l6 and is now free to handle other calls. a

The common locking magnet 29 (1 for each frame 24) having locked itself up through its upper armature 45, a circuit is completed from battery 36 via contact 35a to armature 45, contact 46 through winding 30 via conductor 3| to contact 32 via the spring controlled member 41 in selector 2| and to ground at 33. The wiper 48 moving in accordance with the dialing of dial I! permits the spring 49 attached to member 41 to pull up said member very quickly so that the magnet 29 (which is a slow-release magnet) can hold up during the break that occurs on account of the movement of member 41 in the selector; but when wiper 43 returns to normal, in which normal position as shown in Figure 1 it rests against or operates member 41, causing 41 to contact contact 32, it is acting against spring 49 and dash-pot 49a and the breaking period is delayed, so that magnet 29 cannot hold up over this period and consequently falls, breaking the connection with battery 36. This releases the common locking magnet 29, which, together with through their cut-off relays same, and therefore one selector 2I may be used the connecting frame 24, is "ready forthe next call.

After the board is free and selector 2I is released, both free for the next call, there only remain engaged, holding subscriber Ills call, one vertical rod 38 and one horizontal rod 31. The rest of the lines or rods passing through connecting frame 24, together with associated selector 2I, are available for other calls; so that as many as 39' or 40 conversations may be going on simultaneously through board 24' and still selector 2I is free for other calls.

In general, one board is assigned to work in conjunction with each selector, so that to make a complete call from subscriber I0 to subscriber 94,. a minimum or two boards (one connecting frame 24 and one incoming or subscribers frame 240 are required. As many connecting frames 24 may be interposed as required, in the manner shown.

One switch frame will handle a plurality of calls. A number of such frames is employed in a central ofilce, depending upon the trafiic.

Two. types of boards are shown, the connecting frame 24 and the incoming or subscribers frame 240; the appended drawings show two methods whereby these boards may be adapted to existing systems:

a. Subscriber III, at left, is not using subscribers boa-rd 24c and therefore requires a line switch to make a call and a final selector to receive a call, permanently.

b; Subscriber 94, at right of Figure 2, is using frame 240 and thereby eliminates the line switch entirely, and dispenses with the selector after the establishing operation is completed.

From the foregoing, it will be evident that the sequence of operations is as follows:

1. Subscriber II! lifts the receiver from the hook which immediately gives him access to the selector 2| and to. an idle connecting frame 24.

2. Subscriber, upon dialing, operates the selector 2I in the usual manner, which inturn operates the connecting frame 24 to select the outgoing or horizontal line desired.

3. As soon as the frame 24 has made the necessary selection, selector 2| is released, and any other lines connected to its common wire C I6 may use the by a plurality of subscribers. The function of the selector 2| is purely that of setting up the desired connection through the connecting frame 24, on which one vertical rod and one horizontal rod maintain the connection during the talking period.

Upon termination of the talking period, the subscribers line is reconnected to the selector,

ready for another call.

Continuing now with the call above-described, this continues on the trunks II and 12 selected by the dialing, to final subscribers frame 240 (Figure 2), although any number of boards like 24 just described may be interposed between.

. The above described call now enters the final I subscribers board 240 via trunks II and I2 as explained, this board 240 operating then exactly like board 24 described previously:

When this call enters board- 240, circuit is completed as follows: from battery I39 through winding I 49 of selector mechanism 19 via conductor 12a to armature I M of cut-ofi relay 18a (one per line) via conductor I2b'via conductor I2c to winding 13b of individual locking magnet I3, via

conductor I42 to winding 11a of one of the vertical magnets TI of the subscribers or switch frame mechanism 240. From this magnet I1, the circuit continues via conductor I8 to conductor I2, from whence the circuit continues through fram 24 and to subscriber IIJs instrument as already described; returning then on conductor II, the circuit continues via armature I43 of cut-off relay 18a, via common line CI to selector I9.

At the same time, circuit is also completed from conductor 72b via conductor 120 through winding 13a of individual locking magnet I3 (one per line), via armature I44 to conductor I45 to common locking magnet I4 (one per switch frame 240) through windings 14a. and 74b thereof, via conductor 15 to the bottom contact I 46 in selector switch I9 to member 16 in said switch which is grounded at I41. As soon as this circuit is completed, the vertical magnet 11 on the switch frame 240 operates (as previously described) moving its rod and the contact fingers thereon to the position shown in Figure 5B, ready to be operated by the second digit of the subscribers dial.

Individual lock magnet !3 also operates, pulling up its armature $48, which prevents the dialing from dial II going to another free connecting frame connected at I49 (in case frame 240 is busy as presently described). At the same time, the common locking magnet 14 draws up its armatures and locks itself up by reason of current flowing from battery I59 through winding 74a via conductor I5 to contact I46 and ground I41. The locking operation is now completed and the subscribers frame 240 is closed to all other subscribers until the calling subscriber ID has finished dialing the second digit of the number desired, or about 4 seconds time.

Subscriber I6 now dials the second digit of the number desired, which corresponds (for example) to bank contacts 88 in selector l9. Selector 19 will move its wiper to this pair of contacts, as normally, and thus closes circuit as follows: bank contacts 89 via conductor BI to lower winding of horizontal magnet 82, via normally closed armature 93, via battery 93a to conductor SI a back to contacts on the selector bank.

Horizontal magnet 82 being energized, rotates horizontal rod 83 on its. own axis as usual, and brings incoming cams 83 and 89 under-contact fingers 84 and 86 and also 85 and 81 of the vertical rod, facing them on their own level into position shown at Figure 50, thus connecting contact finger 86 with finger 84 through cam 83, and finger 81 with finger 85 through cam 89. Since fingers 86 and 87 are connected to the incoming lines 96 and. 91, and fingers 84 and 35 are connected to subscriber 94s own pair of lines 95 and 95a, it follows that calling subscriber I9 is. now connected with called subscriber 94.

Shunt 90 connects contact 9I with cam 88; upon horizontal rod 83 being rotated by horizontal magnet 82, as described, contact 9| comes into contact with contact 92 and passes talking current through upper winding of magnet 82, keeping it energized as long as the conversation is going on and the talking circuit is unbroken.

Horizontal magnet 82, in operating, also pushes back with its plunger armature 93, putting into circuit the associated horizontal magnet of the alternate board (supposed to be 241)), subscriber I I is now connected to subscriber 94.

The operation of subscriber 94 calling subscriber ID will now be described.

Upon subscriber 94 lifting his receiver from the hook to make a call, a circuit is' established as follows:

From battery 99, via conductor I00, to winding 11b of vertical magnet TI via conductor IOI, conductor I02, connecting strip I03 (described in specifications for subscribers board 240) via subscribers contact finger 84, via line 95a to subscribers telephone set 94, via conductor 95 to contact finger 85 to connecting strip I04, via conductor I05 to side magnet I08, via conductor I01 to contact I08, via conductor I09 into conductor I I back to battery 99.

Vertical magnet 'I'I operates, pulling up the vertical rod I I I into position B, Figure 5, together with all contact fingers thereon (as explained for connecting frame 24). At the same time, side magnet I06 being energized, pulls horizontal rod 83 sideways to the left, bringing outgoing cams H2 and H3 under subscribers own contact fingers 85 and 84 respectively; said cams H2 and II3 are connected with the outgoing lines H4 and H5.

When side magnet I08 pulls horizontal rod 83 sideways, as above explained, it also brings contact II8, which is connected with outgoing line II4, under contact 92 which is connected with the upper winding of horizontal magnet 82. This magnet 82 now operates, rotating horizontal rod 83, as usual, and raising subscribers contact fingers 84 and 85 into position C, Figure 5, as customary, where they remain in contact with outgoing cams H2 and H3, which, as explained, are connected with the outgoing lines H4 and I I5. Battery I ll furnishes current for these outgoing lines as usual.

In operating, horizontal magnet 82 pushes back with its plunger armature 93, which simultaneously cuts off side magnet I08 and puts another horizontal magnet on an alternate board into circuit for another subscriber on the same level desiring to make a call while horizontal rod 83 is busy. Side magnet I08 is now de-energized and side spring II9 would pull back the horizontal rod 83 into normal at right, but that projection I20 at right on rod 83 has first been carried over on the rod, by the action of side magnet I08 and then brought down by rod 83 rotating downward, to engage with projection I2I.

As long as horizontal magnet 82 remains energized by shunt I22 from which it derives part of the talking current, it will keep the horizontal rod 83 down, and the cams (whichever are chosen) up, in position C of Figure as explained. As soon as the talking circuit is broken, however, by the subscribers hanging up, horizontal magnet 82 de-energizes and allows rotary spring on the horizontal rod (not shown here) to rotate horizontal rod 83 back into normal position. This clears projection I20 from pro jection I2I and side spring H9 immediately pulls the rod. 83 back into normal position, at the right, ready for the next call.

Continuing now with subscriber 94s call, this passes on outgoing lines H4 and H5, as explained, through one or more connecting frames 24 and arrives at selector I38, to the banks of which are connected lines I2 and I3 leading to subscriber I0s telephone instrument. Subscriber 94 is now connected to subscriber I0.

It will be understood that one common battery and ground is used for the system and that no attempt has been made to show ringing, busy and other auxiliary circuits, the application of which will be readily understood.

I-Ierewith follows a detailed description of frames. (Figures 3, 4, 5.)

58 denotes a mounting frame of suitable construction, in which is mounted a plurality of vertical rods 38.' A suitableunit could contain 50 such rods of rectangular cross-section, mounted in bearings to permit them to move vertically.

Each rod 38 has connected to it suitable means such as the electromagnet 23, which when energized will raise the rod a desired distance, and which, when de-energized, will release the rod so that it will fall to normal or idle position by gravity.

Each rod has a plurality of pairs of apertures 59, 60, through each of which passes a contact finger II, 04, hinged at their inner ends. All contact fingers in each pair of vertical rows are moved up and down by their associated rod 38, through which they pass. The fingers are insulated from the rods but all fingers in each vertical row are electrically connected so that each row of fingers forms a vertical row of contacts forming one side of a circuit, both vertical rows on the same rod being shown at 4I-44, Figure 1, the associated rod being shown at 38 in said figure. If advisable the fingers may be made of flexible metal, held in normal position by suitable spring means.

Frame 58 also carries supports 6I82 in which are rotatably supported the horizontal rods 31, each of which carries a plurality of cams 63, 63' each cam. insulated from the other and each set of cams on each rod insulated from all other cams. These cams correspond to, and are adapted to interlock and contact with the contacts 4I-44 when the rod 31 is moved into operating position, being arranged in pairs, each pair facing and lifting the contact fingers 4 I-44 corresponding to it on the same level. One cam of each pair is electrically connected to a conductor leading out of the frame, and the other cam of the pair is electrically connected to the opposite conductor of this outgoing trunk.

Horizontal rod 31 is rotated on its own axis by finger 64 which is in turn moved by plunger 84a of horizontal magnet 65 when this is energized.

Herewith follows a detailed description of frame 240 (subscribers board, Figures 2, 3, 4 and 5).

Board 240 is is of the same construction as board 24, having the same type of mounting frame, on which is mounted a plurality of vertical rods III. A suitable unit could contain 50 such rods of rectangular cross-section, mounted in bearings to permit them to move vertically.

Each rod I II has connected to it suitable means such as the elecromagnet 11 which when energized will raise the rod a desired distance, and which, when dc-energized, will release the rod so that it will fall to normal or idle position by gravity.

Each rod has a plurality of apertures, arranged four in a row, through each of which passes a contact finger, 84, 85, 88, 81, hinged at their inner ends. All contact fingers are moved up and down by their associated rod III, through which they pass. The fingers are insulated from rods, but all the 1st fingers fro-m the left in each horizontal row of four (81, Figure 2) are electrically connected together so that each row of fingers forms a vertical row of contacts forming one side of a circuit; in the same manner all the 3rd fingers from the left in each horizontal row of four (86, Figure 2) are electrically connected together so that each row of fingers forms a vertical row of phone instrument (94) contacts forming the other side of the same circuit. 2nd and 4th contact fingers from the left in each horizontal row of four fingers (84 and 85, Figure 2) are each connected to the one side of a particular subscribers line,- leading to his tele- The associated rod is shown at III in said Figure 2. If advisable, the fingers may be made of flexible metal, held in normal position by suitable spring means.

, While in positions A and E, Figure 5, contact fingers 85 and 84 rest on, and make electrical contact with, strips of metal I04 and I93 respectively, which are insertedin the bottom of the 2nd and 4th apertures from the left in each horizontalro-w of four, of each vertical rod III, but insulated from said rod. When, however, contact fingers-85 and 84 are lifted intopositionC, Figure 5, by the movement of'horizontal rod 83, as de scribed herein, contact between said fingers 84 and 85 and connecting strips I83, I04 is broken.

The said mounting frame also carries supports 7 similar to 6I62 on frame 24, already described, in which are rotatably supported the horizontal rods 83, each of which carries a plurality of cams arranged in two pairs, 88, 89 and H2, H3, each cam insulated from the other, and each set of cams on each rod insulated from all other cams. Cams 88 and 89 correspond to and are adapted to interlock and contact with the contactfingers :84, 86' and 85, 81 respectively in normal position;

cams II2 and-H3 correspond to and are adapted to interlock and contact with the contact fingers 85 and 84 respectively only, when the horizontal rod 83 is shifted to the left by side magnet I86.

These cams are arranged in pairs each pair facing and lifting the contact described above, on the same level. One cam of each pair H2, H3 is electrically connected to a conductor leading out of the frame, and the other cam of this pair is electrically connected to the opposite conductor of this outgoing trunk. Y

The other pair of cams, 88, 89 has no connection, these cams connecting through themselves contact fingers 84, 86 and 85, 81 respectively, when the horizontal rod 83 is rotated in the proper position.

Horizontal rod 83 is rotated on its own axis by finger 82a which is in turn moved by plunger 82b of horizontal magnet 82 when this is energized.

A suitable electromagnet I86 is provided to shift the entire horizontal rod 83 a suitable distance to the left, when subscriber 94wishes to make a call, thus bringing cams H2 and H3, which are connected to the outgoing lines H4 and I I5, under the subscribers contact fingers 85, 84. When horizontal rod'83 has thus been shifted to the left by side magnet I06 and then rotated by horizontal magnet 82 (as described in the operation) a metal projection I29 on the rod engages with a corresponding projection of metal I2I on the frame, which projections hold rod 83 in shifted position against spring II9, but as soon as the talking circuit is broken by the subscriber hanging up, horizontal magnet 82 releases,

into position B,'Figu're 5. Only one vertical'rod at a time can thus" be in position B in-each frame. Upon the subscriber dialing, the selector associated with-said frame will energize through its bank contact the horizontal magnet connected with those particular selector contacts dialed, and this magnet will rotate its horizontal rod into position (L-Figure 5, so that the cams'on said horizontal rod will raise into position C whatever vertical contact fingers on its own level are extended into position B, Figure 5. Since the vertical line on which said subscriber is' making his call is the only one in the frame having its contact fingers and vertical rod in this position B, it follows that only thosecontact fingers in'the incoming line can be raised in position C. Further, only those fingers among them which are on the same level as the horizontal rod selected by the subscribers dialing will be raised by the cams on the horizontal rod into position C, which is the final interlocking position. The vertical magnet and the selector are then cutout by the operation of the cut-off relay and the vertical magnet then drops its rod;

For outgoing calls in frame 240: subscriber, by lifting .his receiver, closes a circuit by which the vertical magnet operating the rod on which his contact fingers are located is energized through its lower winding. It raises its vertical rod, in cluding this subscribers fingers, into position B, as usual. At the same time, the side magnet shifts the horizontal rod on that particular level to the left, bringing the outgoing cams on said horizontal rod under the subscribers contact fingers.

As soon as this is concluded, the horizontal magnet becomes energized and rotates the horizontal rod, bringing said outgoing cams up under subscribers contact fingers and lifting them into position C, as usual; they are then connected with the outgoing lines.

The vertical rod in this case is cut out of the circuit by horizontal magnet pushing back its armature, in operating, which armature connects the vertical magnet 'II (lower winding) with the battery.

Construction of locking mechanism, Figure 6.- This has been described in connection with Figure 1 and the construction of same will be evident from Figure 6.

The magnet 29 may be any suitable type of slow-release magnet having a dash-pot 54 operating in the usual manner. The rod 55, when a winding of the relay is energized, draws up the upper armature 45 connected thereto but in-' sulated therefrom at 56; this armature is connected to but insulated at 51 from'the lower armature 21 which is also drawn up, breakingcontact with all the individual magnets 26.-

Simplified diagram, Figure 7.-Subscriber I0 calling subscriber 94the line goes through lines I2 and I3 through line switch l3a and enters lock of board 24 on line 5I, and at the same time via lines C and I5a into selector 2!." Selector 2| operates board 24 via lines 66a and 16a; incoming lines 40 and 43 are then connected with outgoing trunks 'II and 72 Entering the lock of board 240 on line 12, the call also passes into selector 19 on lines 0-1 and 12a. Selector I9 operates board 240 via lines 8| and am and the incoming lines 96 and 91 are then connected to lines and 9500 which are the subscribersindividual lines leading to his instrument 94.

Subscriber 94 calling subscriber I8 the line goes through conductors 95 and 95a to board 240 on which the subscribers contact fingers are located, via trunks H4 and H5 into lock I and then into selector I3l on lines I32 and I33, which selector operates a board similar to 24. Incoming trunks I34 and I35 are now connected with outgoing trunks I36 and I3! ending on incoming selector I38, which connects trunks I35 and I31 with lines I2 and I3 leading to subscriber I0s instrument.

It will be noted that subscriber I0 is not using frame 240 and therefore requires the line switch l3-a and incoming selector I38 above mentioned. Subscriber 94 is using frame 246 and thus eliminates all permanent line switches and selectors.

What is claimed is:

1. In a telephone system, a central office, a plurality of line circuits terminating therein, each having impulse mechanism connected therewith, a switch common to said circuits, a switch frame and operating mechanism therefor connected to said switch, said frame carrying a plurality of contacts connected to said line circuits, operating mechanism for actuating said frame under control of said impulse mechanism for closing contacts connected to two of said line circuits, and means for locking said switch frame to prevent other line circuits from operating the same until after said closed contacts are opened.

2. In a telephone system, a plurality of circuits, impulse mechanism for each of said circuits, a selector switch common to said circuits, a switch frame and operating mechanism therefor connected to said selector switch, a plurality of contacts carried on said frame and connected to said circuits, operating mechanism for actuating said frame under control of said impulse mechanism for closing contacts connected to at least two of said circuits, and means including a magnetic lock for said frame to prevent other circuits from operating said frame until after the aforesaid connected circuits disconnect.

3. A telephone system comprising a plurality of circuits each having impulse mechanism connected thereto, a selector switch common to said circuits, a switch frame including a plurality of vertical bars having apertures formed therein, contact fingers mounted on said frame and each extending through one of said apertures, magnetic means for moving said bars vertically, said bars being reset by gravity, a plurality of horizontal rods rotatably mounted in said frame and carrying cams adapted to engage said contact fingers, and magnetic means for operating said horizontal bars, said magnetic means being conjointly controlled by said selector switch and said impulse mechanism.

4. A telephone system comprising a plurality of circuits each having impulse mechanism connected thereto, a selector switch common to said circuits, a switch frame including a plurality of vertical bars having apertures formed therein, contact fingers mounted on said frame and each extending through one of said apertures, magnetic means for moving said bars vertically, said bars being reset by gravity, a plurality of horizontal rods rotatably mounted in said frame and carrying cams adapted to engage said contact fingers, electromagnetic means for, operating said horizontal bars, locking means operable upon the entrance of a call from one of said circuits adapted to lock and close said frame to all other calls until after a selection has been made by energizing one of said magnetic means to raise its bar, connections between said electromagnetic meansand said selector switch whereby said selector switch will energize the electromagnet connected with the contacts selected by said impulse mechanism, thereby causing said magnetic means to rotateits horizontal rod to bring its cams in contact with cooperative fingers.

5. An automatic telephone system comprising subscriber's lines, switching apparatus connect-. ed thereto for interconnecting the same including a switch common to a plurality of said lines, means including a cut-off relay connected to each of said lines for disconnecting the same from said switch thereby freeing said switch, means associated with said first means and including a frame having movable contacts thereon for interconnecting said lines to by-pass said switching apparatus connected thereto, and locking mechanism associated with said frame whereby access to the same is prevented when any two said lines are connected thereby.

6. In a communication system of the class described, a plurality of lines, a line switch con nected to each of said lines, a circuit extending from each of said switches and including a switch common to said lines, a switch frame connected to said last switch and having contacts thereon connected to said lines, a cut-off relay for each line adapted to disconnect same from said last switch, a locking relay. for each frame adapted to prevent the access to any line thereto during the time said frame is holding a connection between any two of said lines.

'7. In a communication system of the class described, a plurality of lines each having impulse mechanism connected therewith, arswitch common to said lines, a switch frame and operating mechanism therefor connected to said switch, said frame having a plurality of contacts connected to said lines, means under the control of said impulse mechanism for actuating said switch frame operating mechanism to close contacts connected to two of said lines to connect the same, and means for locking said switch frame to prevent another line from operating the same until the aforesaid connected lines disconnect.

8. In a communication system a switch frame, a plurality of vertical movable bars thereon, said bars having apertures formed therein, a plurality of line contacts supported on said frame each extending through one of said apertures and adapted to be moved by said bars, a plurality of horizontal movable rods, a plurality of cams on each rod, each cam corresponding to one of the aforesaid line contacts, electromagnetic means for moving said vertical bars, and electromagnetic means for moving said horizontal'rods whereby said cams will be brought into contact with said line contacts.

9. The switch frame as claimed in claim 8 wherein the vertical bars cause the line contacts to move from a non-operative position to an operative position and the horizontal rods cause the cams to contact with the line contacts when the latter are in operative position.

10. The switch frame as claimed in claim 8 having a locking mechanism under the control of a line connected thereto whereby said frame is rendered inaccessible to all other lines: when any pair of contacts are closed thereon.

MAURICE ROSIN. 75 V

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