US1762751A - Telephone system - Google Patents

Description

June 1930- E. P. G. WRIGHT 2, 51

TELEPHONE SYSTEM Filed Oct. 26. 192B OPERATED a/v 190mm 5TP T ONE lNVENTOH sM0/v0 E 61 WRIGHT A fro/ms? Patented June 10, 1930 UNITED STATES PATENT OFFICE ESMOND P. G. WRIGHT, OI" BURWOOD, ENGLAND, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE SYSTEM Application filed October 26, 1928, Serial No. 315,141, and in Great Britain December 17, 1927.

This invention relates in general to telephone systems and more particularly to systems which employ automatic switches for establishing conversational connections.

The object of this invention is to increase the capacity of selective switches and the flexibility of the system in which these switches are incorporated.

Heretofore selecting switches with two sets of brushes and two terminal banks have been arranged so that both sets of brushes are operatively associated with their corresponding banks during the automatic selection of an idle set of terminals and arranged so that, after said selection, the set of brushes, which is in contact with the selected set of terminals, is rendered effective to the exclusion of the other set of brushes. Other selecting switches have been so arranged that only one set of brushes is operatively associated with its corresponding bank during the automatic selection of an idle set of terminals, brush selection having preceded said terminal selection. In some of these switches brush selection depends upon the character of the digit which controls the primary movement of the switch and in others it depends upon the character of a digit which is prefixed to the di it which controls the primary movement 0 the switch. A third class of selecting switches has been arranged to absorb the first series of pulses which are received, such switches being used in areas in which the subscribers numbers are made up of a varying number of digits' According to this invention a switch is provided having a plurality of sets of brushes cooperating with respective banks of terminals and so arranged that under certain conditions all sets of brushes are efi'ectii'e to simultaneously test the terminals in their banks and under other conditions one set of brushes is effective to the exclusion of the other sets.

According to another feature of the invention a switch is provided with a plurality of sets of brushes which cooperate with respective banks of terminals, and with a set of contact springs operable in certain primary positions of the switch for restoring the brushes to normal and for causing one only of the sets of brushes to be operatively associated with its terminal bank during the automatic selection, of an idle set of terminals, which follows a repositioning of the brushes by a primary movement of the switch.

To illustrate how the new switch may be used, assume an exchange area in which numbers from 2,000 to 7,999, from 80,000 to 81,999 and from 88,000 to 89,999 are assigned to subscribers lines, the number 92 is assigned for calls, to complaint operator, and 0 is assigned for calls to toll recording operator. A first selector in an exchange of such an area, arranged .in accordance with this invention, provides groups of 20 trunks each when the first digit of the called numher is one of the six digits 2, 3, 4, 5, 6 and 7, both sets of brushes being operatively associated with the contacts in their respective banks, so as to automatically select the first idle outlet encountered by either set of brushes. When the first digit of the called number is 0 or 9, groups of ten trunks each are provided and the set of brushes which cooperates with the main bank is rendered effective to the exclusion of the other set of brushes. When the first digit of the called number is 8 the brushes are restored to normal after having been stepped to the 8th level; the next digit of the called number being either 0, 1, 8 or 9 the set of brushes which cooperates with the auxiliary bank is rendered eifective to the exclusion of the set of brushes which cooperates with the main bank. Thus groups of 20 outlets each are provided on the second, third, fourth, fifth, sixth and seventh levels, and two independent groups of 10 outlets each are provided on each of the remaining levels.

Referring to the drawing which diagrammatically illustrates one embodiment of the invention, A represents a calling subscribers substation which is automatically connected either by a line switch as indicated schematically, or by a line finder, with an idle selector S. The selector is of the step-by-step type and has a capacity of 200 sets of terminals divided into two banks hereinafter referred to as the main and auxiliary banks. There are 100 sets of terminals per bank divided into 10 levels, 10 sets of terminals per level. The selector is equipped with two sets of brushes arranged on a single shaft so that brushes 19, 2t) and 21 cooperate with the main bank and brushes 22, 23 and 24: cooperate with the auxiliary bank. By a vertical movement of the shatt the brushes are stepped up to the desired level and by a rotary movement they are advanced to make contact suc essively with the sets of terminals in the selected level. The contact springs of switching device X are operated when the brushes are stepped to a certain level which in our illustrati n we have as sumed to be level 8. The contact springs of switching device Y are operated on certain other levels which in our illustration we have assume-d to be levels 2, 8, 4, 5. 6 and 7. Relay 9 switches the incoming circuit from one set of brushes to the other and relay 1O cooperates with contact springs X to cause the restoration of the brushes to normal. Except for these modifications the selector one ot' the usual and well-known construction.

Upon seizure of the selector, relay 1 operates in a circuit from battery through its upper winding, through the top outer contact of relay 7, line 11, bottom outer contact of relay 7, lower winding of relay 1, contact 17 ot the eleventh rotary step springs, and secondary winding of the dial tone induction coil, to ground. Relay 1 eperates relay 2 in a circuit. from battery through its winding, to ground on the top inner armature of relay 7. Relay 2 connects ground to conductor 12 for the purpo-=e oi holding the antecedent switches.

When the subscribers calling device is operated to send a series of pulses corresponding to the first digit of the callezL number, relay 1 releases and reoperates each time the line circuit is opened and closed by the calling device. Relay 2 is slow to release and its contacts remain in the operated position during pulsing although the circuit through its winding is opened every time relay 1 relcasts. Each release of relay 1 closes a circuit from ground on the top inner armature of relay '7. through the back contact of relay 1. front contact of relay 2, Winding of relay and winding of vertical stepping magnet to battery, operating relay 3 and magnet The operation of magnet 4 steps the brushes up to the first level thereby closing oil-normal springs ON. lVith relay 3 operated and the ON springs closed relay 5 operates in a circuit from battery through its windings, through contact 18 of the eleventh rotary step springs, contact 1st of the ON springs, contact 16 of the X springs,

and front contacts of relays 3 and 2. to ground. Relay 5 locks, under control of the rotary stepping magnet G, to ground on the top inner armature of relay'T. Each rcoperation of relay 1 opens the circuit through the windings of relay 3 and magnet 4, so that vertical magnet 4 operates and releases as many times as there are units in the first digit dialled, stepping the brushes up to the corresponding level. Relay 3 is slow to release and holds operated until all of the pulses corresponding to the first digit have been received.

The further operation of the switch depends upon the level to which the brushes are stepped by the first set of pulses received. Assume that the first digit of the called number is either 0 or 9 and that the brushes have been stepped to the corresponding level. Since neither the X nor Y contact springs are operated on either of these levels, neither of relays 9 or 10 is operated. The release of relay 3 closes a circuit from battery through the winding of rotary stepping magnet 6 through the back contact of relay 3 and front contact of relay 2, to ground. The operation of magnet 6 in this circuitrotates both sets of brushes into contact with the first set of terminals in the selected l vels of their respective banks, but, since relay 9 is not operated, brushes 19, and 21 are effective to the exclusion of brushes 22, and 24. Relay 5 releases when magnet 6 operates, thus causing the release of magnet 6. \Vith magnet 6 released, a circuit is closed from battery through the windings of relay 5, through contact 18 of the eleventh rotary step springs, contact ll of the ON springs, contact 16 of the X springs, back contact of the rotarv magnet (5, Winding of relay '7. and from contact of relay 2, to ground. If the first set of terminals in the main bank is idle relay 7 operates, but relay 5 is marginal and does not operate in this circuit. If this set of terminals is busy, relay 5 reoperates and relay 7 does not operate since its winding is short-circuited by ground on the terminal with which test brush 21 in contact. The reoperation of relay 5 causes the reoperation of rotary stepping magnet (3, advancing the brushes to the next set of terminals. The brushes are in this manner successively advanced from one set of terminals to the next until an idle set is encountered, whereupon relay 7 operates to prevent their further advance. Relay switches the incoming circuit from the windings of relay 1 to brushes 19 and 20, which are in contact with the terminals or" the selected trunk, thereby causing the release of relays l and 2. By the operation of relay 7 ground is temporarily connected through the front contact of relay 2, bottom inner front contact of relav 7,

- 1 relay 9.

back contact of relay 9, and through test brush 21 to the test terminal of the selected I operation of release magnet 8 in a circuit from battery through its winding, through off-normal contact 13, back contact of relay 2. back contact of relay 1, and back contact of relay 7, to ground. The operation of the release magnet causes the switch to be restored to normal.

N ow assume that the first digit of the called number is one of the digits 2, 3, 4, 5, 6 and 7. After the brushes have been stepped to one of these levels, springs Y are operated thereby causing the operation of After the first series of pulses have been received the release of relay 3 causes the operation of the rotary stepping magnet 6 and the consequent rotation of both sets of brushes into contact with the first set of terminals in the selected level of their respective banks. The operation of magnet 6 releases relay and the release of relay 5 releases magnet 6. If the terminals, with which brushes 19, 20 and 21 are in contact, are idle, the release of relay 5 causes the release of relay 9. With relay 9 and magnet 6 released, a circuit is closedfrom battery through the windings of relay 5,, through contact 18 of the eleventh rotary step springs, contact 14 of the ON springs, contact 16 of springs X, back contact of magnet 6, winding of relay 7, and front contact of relay 2, to ground. Relay 7 operates but relay 5 does not operate in this circuit. The release of relay 9 and operation of relay 7 connects the incoming circuit to brushes 19 and 20, and connects ground through the top inner contact of relay 2,

front contact of relay 7 and back contact of relay 9, to brush 21, thus rendering this set of terminals busy to any other hunting selector. If the terminals, with which brushes 19, 20 and 21 are in contact, are busy, relay 9 holds in a circuit from battery through its winding, through the back contact of relay 10, front contact of relay 9, back contact of relay 7, front contact of relay 2, and test brush 21 to ground on the test terminal; and if at the same time the terminals, with which brushes 22, 23 and 24 are in contact, are idle, relay 7 operates as soc-n as magnet 6 releases.

Relay 7 connects a temporary busy ground through test brush 24 to the test terminal of the selected set, and connects the incoming circuit through front contacts of relay 9 and through brushes 22 and 23 to the terminals of the selected idle trunk. If both sets of brushes are in contact with busy sets of terminals relay 9 holds, when relay 5 releases; but relay 7 does not operate, since its winding is short-circuited by the busy ground on the test terminal with which brush 24 is in contact. lVhen magnet (3 releases, relay 5 reoperates closing the circuit through the winding of rotary magnet (3. Thus, magnet 6 is reoperated after each rotary step, if both sets of brushes are in contact with busy sets of terminals; and the brushes are advanced successively from one set of terminals to the next until an idle set of terminals is encountered, at which time relay 7 operates. If relay 9 has released the operation of relay 7 connects the incoming circuit to brushes 19 and 20 but if relay 9 has not released the operation of relay 7 connects the incoming circuit to brushes 22 and 23. The further operation of the switch is similar to that described when the first digit of the called number is either 0 or 9.

Consider next the operation of the selector if the first digit of the called number 8. With the brushes stepped up to the eighth level, springs X are operated, thereby releasing relay 5. pulses have been received the release of relay 3 closes a circuit from battery through the upper winding of relay 10, through con tact 15 of springs X, back contact of relay 10, back contact of relay 3, and front contact of relay 2, to ground. Relay is a two-step relay and when energized in this circuit closes its bottom inner armature and front contact Without closing or opening any other contacts, and when thus operated its lower winding is short-circuited by contact of springs X. The release of relay 3 also closes a circuit from battery through the winding of release magnet 8, through the back contact of relay 10, contact 15 of springs X, back contact of relay 10, back contact of relay 3, and front contact of relay 2, to ground. Release magnet 8 operates in this circuit thus restoring the brushes to normal. The opening of contact 15 removes the short-circuit from the lower winding of relaylO, and this relay now completely up crates. When fully operated relay 10 locks in a circuit from battery through its upper and lower windings in series, through its own front contact and front contact of relay 2, to ground. The complete operation of relay 10 also closes an obvious circuit through the winding of relay 9, and the resulting operation of relay 9 renders brushes 22, 23 and 241 effective, to the exclusion of brushes 19, and 21. The next series of pulses received by the selector steps the brushes up to one of levels 0, 1, 8 and 9 according to which of these corresponds to the After the first series of second digit of the called number. lVhen the switch is moved elf-normal by the first pulse of this second series, relay 5 reoperates in a circuit from battery through its windings, through contact 18 of the eleventh rotary step springs, contact 14 of the ON springs, front contact of relay 10, front contact of relay 3, and front contactof relay 2, to ground. The release of relay 3 attcr the last pulse has been received closes the circuit through the rotary stepping magnet- 6, both sets of brushes being advanced into contact with the first set of terminals in their respective banks. It the first set of terminals in the auxiliary bank is idle, relay 7 operates as soon as magnet (3 releases. It the first set of terminals is busy relay 5 reoperates in a circuit from battery through its winding, through contact 18 of the eleventh rotary step springs, contact l i of the OK springs, frontcontact of relay 10, back contact 01? magnet (5. back contact of relay 7, front contact of relay 9, and test brush 2%, to ground on the test terminal of the busy set, and r lay 7 does not operate since the ground on the test terminal. shortcircuits its winding. The rcoperation of relay 5 closes the circuit t'or rotary stepping magnet 6 thereby advancing the brushes to the next set of terminals. \Vhen an idle s of terminals is encountered the operation of relay 7 connects the incoming c 'cuit through t'ront contacts of relay 9 and through brushes 22 and 23 to the terminals of the selected trunk. The further operation of the switcn is similar to that described when the irst digit of the called number is either 0 or 9.

From the foregoing explanation it will be seen that the present invention provides in a simple method a switch capable of performing the combined functions of a selector havin access to 20 trunks per group, a selector having access to 1.0 trunks per group. and a selector capable of absorbing the first digit dialled. It will be further noted that the same test relay serves to test in the main bank and in the auxiliary bank. It is understood that a similar arrangement may be applied to a PBX final selector.

\Vhat is claimed is:

l. The combination in an automatic switch of a pluralit of terminal banks, a plurality or sets of brushes for cooperating with said terminal banks, means for operatively associating any one 01" said sets of brushes pith the terminals in its corresponding bank, and means for operatively associating all of said sets simultaneously with their corresponding banks.

2. In an automatic switch, a main terminal bank and an auxiliary terminal bank, a set of brushes for cooperating with the main bank, a set of brushes for cooperating with the auxiliary bank. means effective in certain primary positions of the switch for operatively associating all of said sets oil brushes with their corresponding banks, means effective in other primary positions of the switch for causing the restoration oi": the brushes to normal, and means ell'ective after another primary movement of the switch for operatively associating one of said sets of brushes with its corresponding bank to the exclusion of the other set.

3. In an automatic switch, a main terminal bank and an auxiliary terminal l: nk. each comprising a plurality of levels of terminals, groups of trunks connected to the terminals in certain levels of the main bank, independent groups of trunks connected to the terminal in the same levels of the auxiliary bank, and independent groups of trunks connected to the terminals in other loves of both banks.

4. In an automatic switch, a first terminal bank, a second terminal bank, a set of brushes for cooperating with said first bank, a set of brushes for cooperati with said second bank, means "for operatively associating either of said sets of brushes with the terminals in its corrcspoml bank, and means for operatively a both of said sets of brushes with the terminals of both banks simultaneously.

In a two-motion selectingswitch, a main terminal bank and an auxiliary terminal. bank, a set of brushes for cooperating with the main bank, a set of brushes for (o operating with the auxiliary bank, and means effective in certain primary positions of the switch for determining whether the brushes in their further movement shall have access to the main bank, or to the auxiliary bank, or to both of said banks simultaneously.

6. In a two-motion selecting switch. dupli- "ate sets of brushes and terminal banks. a test relay, a contact device effective in certain primary positions of the switch, and means controlled by said test relay and said contact device for switching from one set of brushes to the other.

7. The combination in a two-motion select ing switch of duplicate sets of brushes and terminal banks, means for switching from one set of brushes to the other, means tor testing contacts in both banks simultaneously, and means actuated in a certain primary position of the switch for restoring the brushes to normal and for operating said brush switching means.

8. The combination. of a calling sul scribers substation, a calling device at said station, a two-motion selecting switch comprising duplicate sets of brushes and termi nal banks, means for connecting said station with said switch, means for positioning both sets of brushes by a primary movement of the switch, said means actuated by impluses of current created by operation of the til) Elf)

aforementioned calling device, and means actuated in certain primary positions of the switch for restoring the brushes to normal to effect an absorption of the first series of current impulses.

9. In an automatic switch, a first terminal bank and a second terminal bank, a set of brushes for cooperating with said first bank, a set of brushes for cooperating with said second bank, a relay for switching from one set of brushes to the other, a contact device actuated in certain primary positions of the switch for operating said switching relay, a second contact device actuated in some other primary position of the switch for restoring the brushes to normal, and means effective after said restoring of the brushes and after another primary movement of the switch for rendering the second set of brushes effective to the exclusion of the first set.

10. In a two-motion selecting switch, afirst terminal bank and a second terminal bank, a set of brushes for cooperating with said first bank, a set of brushes for cooperatin with said second bank, a relay for switching from the first set of brushes to the second set, a contact device actuated in certain primary positions of the switch for operating said switching relay, a second relay, a second contact device actuated in some other primary position of the switch for operating said relay and restoring the brushes to normal, a test relay efl'ective to test the terminals in the first bank when said switching relay is not operated and effective to test the terminals in the second bank when said switching relay is operated, and means comprising said second contact device and said second relay effective after said restoring of the brushes to normal and after another primary movement of the switch for rendering said second set of brushes effective to the exclusion of the first set.

11. In a two-motion automatic switch, a first terminal bank and a second terminal bank, a set of brushes for cooperating with said first bank, a set of brushes for cooperating with said second bank, a relay for switching from the first'set of brushes to the second set, a test relay efli'ective to test the terminals in the first bank when said switching relay is not operated and effective to test the terminals in the second bank when said switching relay is operated, a contact device actuated in certain rimary positions of the switch for operating said switching relay, means including said switching relay and said test relay effective when said contact device is operated for testing the terminals in both banks simultaneously, a third relay, a second contact device actuated in some other primar position of the switch for operating sai third relay and for restoring the brushes to normal, and means including said test relay and said third relay effective after said restoring of the brushes to normal and after another primary movement of the switch for testing the terminals in the second bank to the exclusion of the terminals in the first'bank.

12. In a two-motion automatic switch, a first terminal bank and a second terminal bank, a set of brushes for cooperating with said first bank, a set of brushes for cooperating with said second bank, a relay for switching from the first set of brushes to the second set, a test relay, a contact device actuated in certain primary positions of the switch for operating said switching relay, a third relay, a second contact device actuated in some other primary position of the switch for operating said third relay and for rcstoring the brushes to normal, means including said test relay effective when said switching relay and said third relay are not operated for testing the terminals in the first bank to the exclusion of the terminals in the second bank, means includin said test relay and said switching relay elIective when the first mentioned of said contact devices is actuated for testing the terminals in both banks simultaneously, and means including said test relay and said switching relay effective after said restoring of the brushes to normal and after another primary movement of the switch for testing the terminals in the second bank to the exclusion of the terminals in the first bank.

In witness whereof, I hereunto subscribe my name this first day of October, 1928.

ESMOND P. G. WVRIGHT.

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