US1307057A - ltjndell - Google Patents

Description

A. E. LUNDELL. TELEPHONE EXCHANGE SYSTEM.

APPLICATION HLED DEC. 29,1916.

Patented June 17, 1919.

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ALBEN E. LUNDELL, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHAN GE SYSTEM.

Specification of Letters Patent.

Patented June 17, 1919.

To (all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a citizen of the United States, residing at New York, in the county of Bronx and State of New York, have invented certain new and useful Improvements in Telephone- Excha-nge Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to automatic telephone exchanges in which automatic switching devices are used for establishing connections between two lines, such as calling lines and trunk lines.

Automatic switching devices of the above defined type operate either as finder or as trunk-hunting switches, 2'. 0., the movable contacts of such switches serve as terminals for one line (for instance, the calling line), and the stationary contacts as terminals of the other line (for instance, the trunk line), or vice versa. Upon thesuccessful operation of the automatic switch, the line seized by the movable contacts must be guarded against seizure by other automatic switching devices, means being provided in association with such switching devices for preventing the seizure of busy lines. Furthermore, means must be provided for controlling the exact centering of the movable contacts on the selected stationary contacts. Itihas been the practice to provide automatic switching devices in which, in addition to the movable contacts by which the conductors forming part of the talking circuit may be extended, two movable contacts are provided through which the testing and the guarding of the line to be extended may be controlled, respectively. In such switching devices, the testing means, such as a marginal test relay, may be used also for controlling the centering of the movable contacts. In order to use a single movable contact for controlling the testing and guarding operations, it has been proposed to provide, in addition to the test relay, another relay by which the centering of the movable contacts may be controlled.

It is the object of the present invention to provide a telephone system in which a single relay is in association with an automatic switching device, by means. of which the above mentioned testing, guarding and centering operations are eantrolled, the

ing and guarding operations of the switching device being controllable through a single movable contact of the device.

The drawing represents as much of an automatic exchange system as is necessary for a full understanding of the present invention.

The line finder and connector switches indicated in the drawingmay be substantially the same as those disclosed in patent to Craft and Reynolds, No. 1,123,696, although obviously this invention is applicable to systems in which line finder and connector switches of a widely varying char acter are utilized, or to systems in which, instead of a line finder, a line switch is used for extending the calling line.

Sequence switches 5 and 62, shown in the drawing, may be and preferably are similar to that shown in patent to Reynolds and Baldwin No. 1,127,808. The numerals which appear adjacent the several sequence switch contacts represent the positions of the sequence switch at which the respective contacts are closed, except the numerals which appear adjacent the sequence switch contacts 6, 63, which represent the positions in which these contacts are opened, and consequently. the positions in which the sequence switches may stop. The sequence switch contacts shown below the horizontal dotted line are controlled by sequence switch 5 and those above such line by sequence switch 62.

The connector switch may be controlled by any wellknown means for seizing calling terminals of the desired line, but preferably is controlled by means of a sending apparatus such as disclosed in patent to A. E. Lundell, No. 1,168,319. A full disclosure of connector circuits arranged to control the testing and private branch exchange hunting operations of the connector may be had from a patent of A. E. Lundell, No. 1,284,392, issued November 12, 1918.

A subscriber at station A desiring to ob tain a connection with a subscriber at station B removes his receiver from the switchhook, whereupon a line relay 1 is energized in the Well-known manner. Relay 1 closes a circuit from ground through a resistance 2, the armature and front contact and the winding of a start relay 3 common to a plurality of subscribers lines, to ground. The start relay closes than a from groaml,

through its armature and front contact, a contact 4 and the power magnet of sequence switch 5, to grounded battery. Upon the closure of this circuit, the sequence switch is moved out of position 1 and under the control of its master contact 6, into position 2. A circuit is then closed from ground, through the armature and back contact of relay 7, sequence switch contact 8, and the winding of a magnet 9, to grounded battery. Magnet 9 attracts its armature 10 and presses thus a brush rod 11 against a roller 12 constantly rotating in the direction indi cated by the arrow. l/Vipers 13, 14 and 15 and brushes 16 and17 carried on the brush rod 11 are thus moved in an upward direction. The wipers are arranged to successively engage sets of terminals arranged in a terminal bank 18, while brush 16 is arranged to wipe over aninterrupter plate 19, and brush 17 to make contact with a conducting segment 20. \Vhenever brush 16 engages a conducting portion of plate 19, a circuit is closed from ground, through brush 16, plate 19, sequence switch contact 21, conductor 22, and the right-hand winding of relay 7, to grounded battery. The relay 7 is marginal and is so adjusted that it will not attract its armature unless both its windings are energized at the same time. For this reason relay 7 will not be operated until wiper 13 engages a test terminal 23 of the calling line, when a circuit is closed from ground, through the left-hand winding of relay 7, sequence switch contact 24, wiper 13, terminal 23, winding of a cut-off relay 25, the right-hand armature and front contact of relay 1, and the winding of the start relay 3, to grounded battery. Relay 25 becomes energized and opens the circuit of relay 1, which in turn causes the dene'rgization of relays 3 and 7. The conducting segments of plate 19 are so arranged with respect to the terminals of bank 18, that,'when the brush 16engages a conducting segment, the line finder wipers are centered upon a set of terminals. Thus relay 7 cannot be come energized until the wipers are properly centered. The left-hand winding of relay 7 will not be energized while the wiper 13 is traveling over test terminals of idle lines or lines engaged in conversation, because the line relays of such lines are not energized. Relay 7, upon energization, opens the circuit of the magnet 9, and the brush rod 11 is thus arrested in its upward movement and held there by a pawl 55. Furthermore, relay 7, upon its energization, closes a circuit from ground, through its armature and front contact, a contact 26 and the power magnet of sequence switch 5, to grounded battery, for moving this sequence switch out of position'2 into position 16. For this reason, upon the deenergization of relay 7, a circuit'through sequence switch contact 8 this circuit the potential on the callingtest terminal, such as 74 of the line leading to station A, is reduced, so as to prevent the seizure of this line by a connector, as will be hereinafter set forth.

The calling line is then extended through wipers 14 and 15 and sequence switch contacts 33 and 34, to a trunk which may then be further extended by automatic or manual means to the called subscribers station B.

After the completion of the conversation, the operator actuates key 29, and thus closes a circuit from grounded battery 35, through the winding of a marginal relay 36, key 29, sequence switch contact 27, wiper l3, terminal 23, and the windings of a marginal relay 37, to ground. Relay 37 becomes energized and closes a shunt around its left-hand winding, whereupon the marginal relay 36 is permitted to operate for actuating signal 38 which indicates to the operator that relay 37 has been actuated. Relay 37 controls operation of thecalling subscribers meter 40. When battery is connected to the relay 37 through resistance 30 and contact 28 of key 29, the relay does not operate, because current of a higher voltage supplied by battery 35 is required for this purpose.

The operator then actuates key 50 and closes a circuit through a contact 51 for moving the sequence switch out of position 16 into position 17. A circuit is then closed from grounded battery, through the winding of a magnet 52 and a sequence switch contact 53, to ground. Magnet-52 attracts its armature 54 and causes thus a pawl 55 to disengage the rod 11. The armature 54 presses the brush rod against a roller 56, constantly rotating in the direction indi cated by the arrow, whereby the wipers and brushes are restored to their normal position. a

When brush 17 engages plate 20, a ground is connectedthrough conductor 57 and contact 58 'formoving the sequence switch into its normal position 1, whereupon magnet 52 and relays 36, 37 and 25 become deenergized. All the apparatus is restored now to normal and is ready to receive a new call.

The line leading to the station A is one of a plurality of lines leading to a private branch exchange. If it is'desired to seize thifs line by means of'a connector, then the operator, or subscriber controlling the establisliinent of the connection from a calling substation to the desired station A causes, in the well-known manner, the energization of a line relay 60 associated with such connector. The line relay closes a circuit from ground, through its armature and front contact, a contact 61 and the power magnet of sequence switch 62 associated with the connector, to grounded battery. Under the control of its normal contact 63, the sequence switch is moved into position 2. A circuit is then closed from ground, through the armature and front contact of relay 60, sequence switch contact 64, and

the winding of a magnet 65, to grounded battery. Under the control of magnet 65, the wipers 66, 67 and 68 are caused to move a distance determined by the tens digits of the number designating the desired line. After the. connector has been set in accordance with the tens digit, relay 60 is caused to release its armature and closes thus a circuit from ground, through a contact 69 and the power magnet of sequence switch 62, to grounded battery, for moving the sequence switch out of position 2 and into position 3. The magnet 65 is then momentarily deenergized, but as soon as the relay 60 is again caused to operate and close a circuit through sequence switch contact 61 for moving the sequence switch 62 out of position 3 and into position 4, the updrive magnet is again operated, due to the reclosure of its above traced circuit, and causes the connector wipers to travel in accordance with the units digit of the called subscribers number.

After the termination of the units impulses, relay 60 again becomes deenergized and closes a circuit through sequence switch contact 69, for driving the sequence switch 62 out of position 4 and into position 7. A

' circuit is now closed from ground, through a sequence switch contact 70, and the righthand winding of a test relay 71, to grounded battery. Relay 71 closes a circuit from ground, through its right-hand armature and front contact, and a contact 72, and the power magnet of the sequence switch 62, to grounded battery, for drivin this sequence switch out of position 7 an into position 9. Relay 71 connects ground, through the winding of a marginal relay 73, its lefthand winding, front contact and armature, and test wiper 68 of the connector, to the calling test terminal 74 of the called line.

If the line leading to station A has been seizedby the line finder, grounded battery is connected through resistance 30, key 29, sequence switch contact 27, line finder wiper 13, and the answering test terminal 23, to the callin test terminal 74. The test terminal 74 is a so connected through the winding of a cut-off relay 25 and resistance 2 to ground. Due to the fact that the shunt closed through the cubofl relay 25 and resistance 2 is of relatively low resistance with respect to the shunt closed through the line finder wiper 13, the relay 73 which is marginal in operation, will not operate; relay 71, however, will maintain its armatures attracted under the control of its left-hand winding. A circuit is therefore closed from grounded battery, through winding of magnet 65, the back contact and armature of relay 73, sequence switch contact 80, and the 75 right-hand front contact and armature of relay 71, to ground. The magnet 65 operates the connector wipers to hunt for an idle line leading to the desired private branch exchange.

The connector switch continues to hunt 1 until relay 71 becomes deenergized. This relay 71 will become denergized as soon as an idle line is encountered, that is to say, a line to the multiple calling test terminals of which no battery is connected through the test wiper of a line finder or connector switch. When the test relay 71 becomes deenergized, it breaks at its front contact the energizing circuit of magnet 65 and closes a circuit from ground, through the righthand armature and back contact of relay 71, a contact 81 and the power magnet of sequence switch 62, to grounded battery, for moving this sequence switch out of position 9 into position 15. From positions 8 to 15 of the sequence switch, contact 82 is closed, and thus grounded battery is connected through a resistance 83 and the left-hand back contact and armature of relay 71 to the multiples of a calling test terminal, which will render the line busy in the same manner as it is rendered busy due to the shunt closed through the test wiper 13 of the line finder." In position 15, contacts 84 and 85 of the sequence switch are also closed and the talking conductors extended to the called line A. The line may now be signaled by any well-known means, a

In the lower left-hand corner of the drawing, it is shown how the test conductor of a direct line is connected to the calling and answering test terminals. The ,reference characters used in connection with this showing are the same as in connection with the private branch exchange line, with the exception that each reference character is primed. It will be seen that the test terminals are not connected direct to the winding of the cut-off relay 25', but through the windings of relay 37. In the same manner as above described, the relay 37 will not operate when battery is connected through resistance 30 and line finder wiper 13 to its winding, but only when the operator 12 actuates the meter key 29 and connects the metering battery 35 to its winding. The operation of the line finder in seizing such a direct line will be the same also in other respects as above described in connection with a private branch eXchange. Due to the fact,-however, that the shunt closed from ground through resistance 2, the winding of relay 25, the windings of relay 37, to test terminal 74, is of a relatively high resistance with respect to the shunt closed through the test wiper of a connector or line finder when the wiper 68 of the connector is caused to engage terminal 74, relay 73 will be energized even if the terminal 74 tests busy. Relay 71 being energized at this time, a circuit is closed from ground, through the right-hand armature and front contact of this relay, sequence switch contact 80, the armature, and front contact of relay 73V and the winding of sequence switch 62, to grounded battery, and this sequence switch'is moved out of position 9 into position 12. Relay 71 being energized, the sequence switch is maintained in position 12 for a sufiiciently long period to permit the release of the connector in any well-known manner.

If the desired direct line is idle, then relay 73 remain deenergized. The relay 71 becomes immediately deenergized and closes a circuit from ground, through its right-hand armature and back contact, a contact 81, and the power magnet of sequence switch 62, to grounded battery. Contact 81 being closed also in position '12, the sequence switch will be moved through position 12 into position 15, which is the talking posi tion. The calling and called subscribers are interconnected by means of a circuit including wipers 66 and 67 of 'the connector and sequenceswitch contacts 84 and 85.

What is claimed is:

1. In combination, a plurality of stationary. contacts, a movable contact, means for operating said movable contact to engage any one of said stationary contacts, means for rendering engaged stationary contacts busy, a test relay having two windings, a circuit for one of said windings including said movable contact, a c1rcu1t for for closing said last mentioned circuit depending on the distance said movable contact has traveled with respect to a certain one of saidstationary contacts, guarding means, means responsive to the actuation of said relay for operating said guarding means, and a circuit for said operating magnet controlled by said relay.

3. In combination, a plurality of stationary contacts, a movable contact, a normally ineffective guarding means for said stationary contacts, a marginal test relay having two windings, a circuit for one of said windings. including said movable contact, operating means for said movable contact controlled by said relay for operating said movable contact to move into association with any one of said stationary contacts, a circuit for the other winding of said relay, means for closing the last mentioned circuit depending. on the distance traversed by .said movable contact with respect to one of said stationary cont-acts, said relay being energized only in response to the simultaneous closure of both said circuits, and means operable upon the energization of said relay for rendering said guarding means eflective.

. In witness whereof, I hereunto subscribe my name this 28th day of December A. D., 1916.

' ALBEN E. LUNDELL.

Copies of this patent'may 'be obtained for five cents each, (byad'dressing the Commissioner of Patents, Washington, D. 0.

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