US1842119A - Telephone system - Google Patents

Description

Jan. 19, 1932. T. G. RICE TELEPHONE SYSTEM 2 Sheets-Sheet 1 Filed April 14, 1930 1m Thomas %4 7//% E'EUIHEHDE 17- Jan. 19, 1932. T. G. RICE 1,842,119

TELEPHONE SYSTEM Filed April 14, 1950 2 Sheets-Sheet 2 Tamil-'- ThumasEenr' ERiuE Patented Jan. 19, 1932 UNITED STATES PATENT orrrcs THOMAS GEORGE RICE, OF LIVERPOOL, ENGLAND, ASSIGNOR T ASSOCIATED TELE- PHONE & TELEGRAPH COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE TELEPHONE SYSTEM Application filed April 14, 1930, Serial No. 443,980, and in Great Britain May 29, 1929.

The present invention relates to telephone systems employing automatic switches and is more particularly concerned with increasing the speed of operation of switches which hunt in two stages.

This is effected according to one feature of the invention by arranging that the switches are adapted to hunt in two stages a for the absence of the same source of potential.

According to a further feature of the invention the speed of operation is increased by dispensing with the usual magnet interrupter relay and by employing a self-interrupting magnet circuit in conjunction with what are referred to as double dog springs which operate on each step of the switch.

According to another feature of'the invention in order to secure a quick changeover from the primary movement of the switch to the secondary movement and in order to terminate accurately the secondary movement of the switch use is made of a high 25. voltage surge from a highly inductive windlhe invention will be better understood from the following description of one method of carrying it into efiect, reference being had to the attached'drawings, of which Fig.

1 shows a finder switch embodying the new circuit features while Fig. 2 shows a finder allotter circuit. It will be understood, however, that this is given by way of example only and that various modifications could be made in the circuit details by those skilled in the art without departing from the spirit of the invention.

When the calling subscriber removes his receiver to initiate a call line relay A is energized over a. circuit traceable from earth at armature 10 of relay B, calling loop, armature 11, upper winding of relay A to battery. Relay A thereupon operates and assuming calling subscriber to be located on the fifth level of the finder switch, the operation of armature 12 disconnects the normal earth from the fifth contact of the vertical bank VB in order to mark the level in which the contacts of the calling line are located.

It will be understood, however, that the dotted conductor shown between the vertical bank VB and the armature 12 represents a series of chain contacts similar to those associated with armature 12, each set of which will be controlled by the line relay of a different sub-station, located on the same level.

Due to the operation of armature l3, earth is disconnected from the private bank contact of the calling line, in order to provide a stop circuit to the automatic rotation of the switch.

Returning now to the operation of armature 12, a circuit may be traced from earth, armature 12, resting contact of armature 14,. conductor 15, winding of the start relay S, Fig. 2, to battery, thereby causing the relay to operate and at its armature 16 earth is extended over the following circuit; winding of the switching relay H1 of the first finder allotter F A1, armature 17 interrupter springs 18, winding of the driving magnet DMl to battery, and in parallel thereto via the winding of the other switching relay H2 of the second finder allotter FA2, armature 19, interrupter springs 20, winding of driving magnet DM2 to battery.

Consequently, both relays commence to operate over the circuits described. Belay H1, however, is arranged to be slightly faster to operate than relay H2 so that upon the operation of this relay the energizing path to relay H2 will then be opened at armature 19.

At armature 21 a locking circuit is provided to relay H1 independently of interrupter springs 18, while at armature 22 the following circuit is completed: earth, armature 22, wiper 23 and associated bank contacts of the finder allotter FAl, conductor 24, winding of relay G of the finder to battery. Relay G thereupon operates over the circuit traced and first makes its light armature 25, thereby completing a circuit from earth at the resting contacts of the off-normal springs N, armature 25, winding of relay C to battery, this same earth connection is also extended via armature 26 and its resting con- 7 tact to the right-hand terminal of relay D. When relay G operates fully, earth at arma ture 27 will be connected to the left hand terminal of relay D so that this relay is now short-circuited.

Considering now the operation of relay C over the circuit previously traced, it will be seen that the following vertical impulsing circuit will now become operative; earth at armature 28 of relay C, arn'iature 29, armature 30, interrupter springs 31, winding of the vertical magnet V to battery. Accordingly, the vertical magnet V energizes and causes the shaft and wipers to be raised from the normal position in the well recognized manner, and as a result the springs DD which are actuated by the outward thrust of the so-called double dog, make contact before the vertical interrupter springs 31 break contact. It should be mentioned at this point that the double dog is moved outwards from the switch shaft whilst each step is being made and thereby opens the double dog springs which re-close when the double dog falls into engagement with the next tooth on the shaft when the step has been completed.

The energizing circuit of the vertical magnet V is thereby held closed after the interrupter springs 31 have broken, by way of the resting contact of armature 32, operated springs DD, resting contact of armature 33 to the initial energizing circuit. Consequently, when the vertical magnet V has completed its full stroke, the so-called double dog will then drop into engagement with the first tooth of the vertical hub on the switch shaft, thereby allowing the springs DD to open and effect a complete opening of the vertical magnet circuit. Upon the complete restoration of the vertical magnet interrupter springs 31, a similar sequence of operations will ensue in order to raise the shaft and wipers a still further step.

It must be mentioned that during the first vertical step, that the vertical selecting wiper 3a is arranged to engage with first bank contact before the off-normal springs are operated, and since this contact is normally earthed the short circuiting path to the right-hand side of the winding of relay D will be maintained by way of the release magnet springs 58, armature 35 and its resting contact and armature 26 and its resting contact. Similarly, also relay C will be maintained operated over a branch of this circuit. Consequently, since the vertical selecting wiper 34: is arranged to bridge adjacent contacts during its movement, the foregoing circuit conditions will then prevail until such time as wiper 34 positions itself upon the unearthed fifth bank contact. In this position the short-circuiting path to the right-hand terminal of relay D is opened, and as a result the consequent high voltage surge from the inductive winding of relay C is then applied via the following circuit: battery, winding of relay C, armature 2'6 and its resting contact, winding of relay D working contact of armature 27 and said armature to earth. Relay D is theref re operated very quickly, in order to open the vertical stepping circuit at armature 30 before the vertical magnet can again energize; and thereafter locks up from battery via resistance 36 and armature 37. The operation of relay D also causes earth at armature 38 to be connected by way of the resting contacts of the rotary off-normal springs RON, to the right-hand terminal of relay F; and earth at armature 39 to complete a circuit to relay E. Upon the operation of relay E, earth at armature l0 is connected to the left-hand terminal of relay F, while at armature 42 the fol lowing impulsing circuit is completed to the rotary magnet R, earth at armature 28 of relay C, armature 29, armature 42, interrupter springs l3, winding of rotary magnet R to battery. Hence the wipers of the finder switch will now be automatically rotated over the bank contacts of the selected level, and here a ain due to the operation of armatures 32 and 33 of relay E the springs DD are again bridged across the interrupter contacts in order to ensure that the magnet shall be completely operated.

It must also be mentioned that the rotary testing wiper 44 is arranged to engage with the first bank contact before the rotary oil'- normal springs RON open, so that in case the first bank contact should be normally earthed, the short-circuiting path will be maintained to the right-hand terminal of relay F from test wiper 44 by way of the resting contact of armature 35, and the working contact of armature 26, while similarly, relay C is again maintained via a branch circuit.

Hence the wipers of the switch will be auto matically rotated due to the self-interrupting circuit of the rotary magnet and as the testing wiper 4a is also of the bridging type the foregoing circuit conditions will prevail until the wiper 44- positions itself on the desired bank contact which is unearthed. In this position, the short-circuiting path to relay F will now be opened and a result relay C will thereupon discharge itself over the following circuit; battery, winding of relay C, armature 26 and its working contact, winding of relay F, armature 40 to earth. Relay F is therefore operated very quickly in a similar manner to relay D, in order to open the rotary impulsing circuit at armature 29 before the rotary magnet is able to energize again; and thereafter locks up in series with relay C via armature 4-0. The operation of relay F causes the calling loop to be extended via wipers 46 and i7, armatures 48 and 49 to the line relay A1 of the first selector, shown schematically at the righthand side of Fig. 1, and at armature 35 completes the following circuit: earth, armature all, working contact of armature 35 and said armature, release magnet springs wiper 4A- and bank contact, armature 13 and its working contact, lower winding of line relay A in series with cut-off relay B to battery. Relay A therefore remains operated over its lower winding, while the operation of relay B removes the normal battery and earth connections from the calling loop at armatures 11 and 12 and at armature 14 recompletes the chain marking circuit. At armature 50 of relay F, earth is extended over conductor 51 by way of bank contact and wiper 52 of the finder allotter FAl, armature 53 and its working contact, armature 17, armature 54, armature 21, winding of the driving magnet DMl to battery, with a parallel path from armature 17 and interrupter springs 18 to the winding of the driving magnet DMl to battery. Accordingly the magnet energizes and prepares to advance the wipers of the switch F111 onto the next set of bank contacts. Upon the operation of the cut-off relay B, the holding circuit to the start relay S was opened at armature 14 and as a result the relay releases and causes earth to be removed from the circuit to relays H1 and H2.

Belay H1 thereupon restores to normal and in turn opens the energizing circuit to the driving magnet DM1 at armatures 21 and 53 so that the driving magnet DMl deenergizes and the wipers of the switch will thereby be advanced onto the next set of bank contacts in the well recognized manner, in order to prepare the next idle find-er circuit in readiness for the initiation of the next call. Due to the disconnection of earth from conductor 24 by the movement of wiper 23, the circuit of relay G is opened whereupon this relay releases and is followed by the release of relays D and E in succession.

Returning now to the operation of relay F, it will be remembered that a loop circuit was extended to the line relay A1 of the first selector, thereby causing the said relay to be operated; relay A1 in turn completes the usual local circuit to the release relay B1.

Upon the operation of the release relay B1, earth at armature 55 is connected by way of the release trunk conductor to the left-hand terminal of relay F, and since relays G, D and E have released due to the stepping of the earthed wiper 23 as previously mentioned, relays F and C will then be maintained energized in series throughout the remainder of the call. in the following circuit: battery, winding of relay C, armature 45, winding of relay F, armature 55 to earth. Relays A and B are maintained energized in series over the following circuit: battery, winding of relay B, lower winding of relay A, front contact of armature 13 and said armature, wiper 44, release magnet springs 58, armature 35 and it front contact, armature 55 and its front contact to earth. The dialled digits are then received from the calling subscriber over the loop circuit to the line relay A1, and in response thereto the wipers of the switch are raised to the desired level.

Upon the release of the connection when both subscribers replace their receivers on the switch hooks, earth will be removed off the release trunk conductor by the last switch in the train, and in consequence thereof the series holding circuit to relays F and O is opened. Upon the release of relay C the following circuit is completed to the release magnet Z; earth, armature 27 of relay G and its resting contact, armature 56 and its resting contact, operated contacts of oil-normal springs N, winding of release magnet Z, conduetor 57, winding of low resistance total calls relay TO to battery. The release of the switch now takes place in the well recognized manner, while the operation of the release magnet springs 58 serves to disconnect the vertical and rotary testing wipers during their reurn motion over the banks. Relay TC is also operated over the circuit traced, and at its armature 59 extends earth over conductor 60 in order to eifect the registration of the call on the total calls meter. In case the condition should arise where all the finders are engaged at a given instant, common conductor 61 will then be found to be free of earth due to the operation of all the various sets of off-normal springs similar to N in Fig. 1, and as a result a convenient stop circuit is thus provided at the twenty fifth and first bank contacts respectively of the finder allotter FAl and FA2, thereby preventing the continuous rotation of these switches during the busy condition. Consequently, should a still further call be received during the all finders busy condition; upon the operation of relay H1 earth will then be connected at armature 22, by way of wiper 23 and 25th bank contact over conductor 62 to an overflow meter, thereby registering the call as lost because all the finders of the group were busy at the time it was made.

v 1. For use in telephone or like systems an automatic hunting switch the continuance of the hunting operation of which is dependent upon the connection of a particular potential to the contacts engaged by the test wiper in which the absence of said potential causes a source of high voltage to be connected up independently of said wiper to terminate the hunting operation- 2. An automatic hunting switch for use in telephone or like systems in which a highly inductive winding is adapted to be connected in series with the relay which operates when a connection is extended to a wanted line to increase the speed of operation of said relay, this relay being shunted by potential picked up over the test Wiper as long as unwanted lines are encountered.

3. An automatic hunting switch for use in telephone or like systems arranged to hunt in two directions for the absence of predetermined potential in which a highly inductive winding is adapted to be connected in series with the relay which operates at the end of the primary hunting movement and subsequently to be connected in series with the relay which operates at the end of the secondary hunting movement in order to increase the speed of operation of the relays.

4. A finder switch for use in telephone or like systems adapted to hunt over a plurality of contacts each corresponding to a group of lines in which a series circuit for each of said groups normally connects a source of potential to each of said contacts, and means for opening said circuit when a line in the corresponding group of lines is calling.

5. A step-by-step hunting switch for use in telephone or like systems a stepping magnet of the switch having contacts for interrupting its own circuit in which springs operated by each step of the switch maintain the circuit of said magnet closed until the switch has stepped.

6. A hunting switch as claimed in claim 5 in which said springs are carried by the retaining pawl which is intermittently moved during the setting motion by sliding over the teeth on the switch shaft.

7. In a telephone system, an automatic switch having a test wiper, test contacts accessible to said wiper and having a particular potential normally connected thereto, means for initiating the hunting operation of said switch, means for continuing the said hunting operation dependent upon said wiper engaging said contacts having said potential connected thereto, and means in said switch responsive to said wiper engaging one of said contacts characterized by an absence of said potential for connecting up a source of high voltage independently of said wiper to terminate the hunting operation.

8. In a telephone system, an automatic switch having a test wiper, test contacts accessible to said wiper and having a particular potential normally connected thereto, means for initiating the hunting operation of said switch, means for continuing the said hunting operation dependent upon said wiper engaging said contacts having said potential connected thereto, a switching relay in said switch for terminating the hunting operation, acircuit for energizing said relay including an inductive winding connected in series with said relay for increasing the speed of operation of said relay, and a circuit for shunting said relay during the hunting operation only as long as said wiper engages contacts having said particular potential connected thereto.

9. In a telephone system, an automatic switch having means for hunting in two directions for the absence of a predetermined potential, a changeover relay for terminating the primary hunting operation, a switching relay for terminating the secondary hunting operation, and an inductive winding connected in series with the changeover relay for increasing the speed of operation of said relay at the end of the primary hunting movement and subsequently connected in series with the switching relay for increasing the speed of operation of said relay at the end of the secondary hunting movement.

10. In a telephone system, an automatic switch having means for hunting in two directions for the absence of a predetermined potential, a changeover relay for terminating the primary hunting operation, a switching relay for terminating the secondary hunting operation, a primary test wiper in said switch for preventing the operation of said changeover relay by shunting said relay as long as said wiper encounters said predetermined potential, a second test wiper in said switch for preventing the operation of said switching relay by shunting said relay as long as said wiper encounters said predetermined potential, and an inductive winding connected in series with the changeover relay for increasing the speed of operation of said relay at the end of the primary hunting movement and subsequently connected in series with the switching relay for increasing the speed of operation of said relay at the end of the secondary hunting movement.

11. In a telephone system, an automatic switch, primary and secondary test contacts in said switch having the same particular potential normally connected thereto, means for removing said potential from a particular primary and a particular secondary test contact, and means for operating said switch in two hunting movements in search of the primary test contact and the secondary test contact characterized by the absence of said potential.

12. In a telephone system, a group of lines divided into subgroups, a test contact for each subgroup, a series circuit in each subgroup normally connecting a source of potential to their respective contacts, means for opening the series circuit of a subgroup when a line therein is calling, a finder switch, and means for operating said finder switch in search of the contact having said potential removed therefrom by the opening of said series circuit.

13. In a step-by-step hunting switch, a stepping magnet for operating said switch step-by-step, a circuit for operating said magnet, contacts on said magnet for interrupting said circuit, another circuit "for said magnet, and springs operated upon each step of said switch for closing and maintaining said other circuit independent of said first circuit until said switch has stepped.

14. In a step-by-step hunting switch having a switch shaft and a retaining pawl therefor, a stepping magnet for operating said switch shaft step-hy-step, a circuit for operating said magnet, contacts on said magnet for interrupting said circuit, another circuit for said magnet, means on said switch shaft for operating said pawl on each step of the shaft, and springs operated by said pawl upon each step of said shaft for closing and maintaining said other circuit until said shaft has completed its step.

15. In a telephone system, an automatic hunting switch having a test wiper, means for initiating the hunting operation of said switch, means for continuing the hunting operation dependent upon said wiper encountering a predetermined potential, a relay in said switch for terminating said hunting operation, a second relay in said switch having a high inductive winding connected in series with said first relay for increasing the speed of operation of said first relay, means for continuously holding said second relay energized over said winding and for preventing the operation of said first relay by shunting said first relay during the hunting 5 operation only as long as said wiper encounters said potential.

In testimony whereof I aifix my signature.

THOMAS GEORGE RICE.

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