US2170885A - Selective switch - Google Patents

Description

ug- 29, 1939 l E. P. G. WRIGHT t 2,170,885

SELECTIVE SWITCH Filed Nov. 28, 1936 E. G. WRIGHT Patented Aug. 29, 1939 UNITED STATES 2,170,885 SELECTIVE SWITCH Esmond Philip land, assignor Incorporated, of New York Goodwin Wright, London, Engto Western New York, N.

Electric Company, Y., a corporation Application November 28, 1936, Serial No. 113,185

Great Britain 12 Claims.

This invention relates to selective switching mechanism and particularly to switches of the two-motion step-b-y-step type common in automatic telephone systems.

It is the object of the invention to increase the adaptability and eiciency of two-motion switches known as the square type, that is switches in which the brushes in their selecting and resetting movements describe a closed rectangle.

In two-motion selector switches of the type in which the brushes retrace their selective movement to reach normal position, it is usual to absorb a directive set of operating impulses by releasing the shaft and return of the brushes to l normal position immediately after the directive movement which is to be absorbed and before another train of directive impulses is received. In case certain but not all directive digits are to be absorbed, the release of the brushes is effected 20 by the closure of shaft-operated springs in response to these certain digits or by means of an additional brush and. associated contacts. These known methods of digit-absorption and discrimination cannot effectively be appliedto the square g5 type of selector switch in which the release time may exceed the interval between succeeding trains of directive impulses. l

According to this invention the absorption oi a directive train of impulses is eiiected in a 30 two-motion switch by the storing ci a part of the impulses oi a digit train on relays, the remaining impulses in the train being effective to advance the brushes of the selector. In the case of im` pulse trains comprising less than a predetermined 5 number of impulses, the absorption is effected without moving the brushes from` normal, some of the impulses of the next train of impulses being absorbed and the succeeding impulses being eiective to advance the brushes in a selective moveo ment. Following a primary selective movement, the switch may be advanced either by a selective secondary movement in response to another train of impulses or by an automatic secondary movement to hunt for an idle set of terminals.

b A feature of the invention is the absorption of the initial impulses of a second digit to extend the interval between digits artificially while the brushes are being returned to normal, only the succeeding impulses of the second digit being 50 effective to selectively position the brushes of the switch.

Further explanation of the invention will be made by describing one embodiment of the invention which is shown schematically in the 55 drawing which forms a part of this specification,

January 17, 1936 The invention is, of course, not limited to the specic arrangement and structure disclosed but is in general applicable to any selective switch to effect a desired digit absorbing operation.

The drawing shows schematically a two-motion square-type selective switch comprising an impulse receiving relay A, a vertical stepping mag-'l net VM, a rotary stepping magnet RM, the brushes RW, TW and VW, and the associated control relays and circuit connections.

In the drawing, capital letters are used as the reference characters for the relays and magnets and corresponding lower case letters with numerical subscripts` are used as the reference characters for the contact springs. associated broken line connections may or may not be provided depending upon the desired operation of the switch. When relay J is not provided the contact spring b2 is connected to ground and contact `tl is connected to contact c5 as shown by the solid line connections. But when relay J is provided contact spring b2 is connected to the front contact oi spring c4 instead of being connected directly to ground, and contact spring tl is connected directly to ground.

The operation of the selector switch shown in the drawing will first be described assuming that relay J is not provided. Upon seizure of the selector switch and closure of the control circuit over the conductors of line L, relay A operates, closing at contact a2 a circuit for operating the release relay B. Relay A thereafter responds to the digit impulses transmitted over line L. Relay B, being slow in releasing, remains operated during the response of relay The release oi relay A, in response to the rst impulse, closes a circuit through the back contact of spring al and contact bl for operating relay C; and relay C, being slow in releasing, remains operated until all of the impulses in the train have been received. The reoperation of relay A, at the end of the iirst impulse, closes a circuit through the front contact of spring al and contacts cl and cl for energizing the left winding oi relay D. The release of Relay J and the relay A in response to the second impulse of the train closes a circuitV through the back contact of spring al, contacts bl and dl, and the right winding of relay D for holding relay D operated; and closes a circuit through the back contact of spring al contact bl the back contact of spring g2, front contact of spring d2, back contact of spring f2, and the upper winding of relay E for operating relay E. Relay E opens at contact el the circuit through the left winding of relay D so that,` upon the opening Voi the circuit through the right winding of relay D when relay A reoperlast impulse of the digit, relay C releases thereby ates at the end of the second impulse, relay D causing the release or relay D. Relay G does not releases. Relay Il.' is held operated by a circuit operate since Contact n2 of the oli-normal springs through its lower winding and contacts e2 and b2. is opened when the switch moves out of normal tacts or" springs g2 and d2, the back contact of the number of the level being three less than the numoI-normal spring nl, contact e3 and the upper ber of impulses in the train. That is, if the first winding of relay F for operating relay F. Relay directive digit is 4, the brushes are stepped up to F' CIOSSS a lOCliing Circuit through its lower windthe rst level of the terminal bank; and if the ing and CentaCtS f3 and U2. The reoperation rst directive digit is 5, 6, 7, 8, 9 or 0, the brushes of relay A at the end of the third impulse closes a are stepped up to level 2, 3, 4, 5, e or l. If the back Contact 0f spring 02, the normally-closed spending to the number of impulses in the sec- COntaCt n2 0f the 01T -nOrInal Springs 0f the Switch, ond directive train. If, however, the rst directive and CentaCt 84, fOr Operating relay G- Relay G digit is 0, relay O is operated when relay C recloses at Contact g4 a circuit for operating relay leases, the circuit for operating relay O being H; and relay H locks through contacts h2 and b4. traced through brushes VW and seventh oir-nor- Witll relay G Operatedy the SeCOnd trein 0f iinmal terminals ofthe associated vertical bank, and pulses inCOlnng OVer line L is eTeCtVe t0 Cause through contacts c3 and h3. Relay O closes a the Operatien 0f the Vertieal magnet VM and adcircuit for operating the rotary-stepping magnet relay C releases at the end of the second train of an idle set 0f terminals, relay T operates. At impulses, relay G also releases; but relay H recontact ti, relay T opensy the circuit for operating mains Operated So that. if the second digit is Zero. magnet RM so as to stop the brushes of the switch the Circuit fOr Operating relay O is open at conon the rst idle set of terminals in the level. tact h3. The third train of directive impulses in- If now it is desired that the switch be arcoming over line L is then effective to cause the ranged to return to normal if a particular digit Operation 0f the rotary-stepping magnet RM and such as 8 is dialed, relay J is provided, its windadvance ol the brushes to a corresponding set of ing being connected to terminal 5 of the vertical tact l, back Contacts Of Springs @"2 and d2, and tact spring tl is connected directly to ground.

first directive train of impulses iS received, relay ment of the switch results. As soon as a train Dalso releases leal/iner the switch ready, as before, of more than three impulses is received by relay remains operated, during the response 0f relay A raised to level i in response to a train of ten irnand magnet VM, Since its left Winding iS enerpulses, the operation of relay O causes the switch gized each time the front contact of spring al to hunt for an idle set of terminals in level 'l closes and its right winding is energized each as hereinbefore described. If the brushes are time the back contact of spring al closes. When raised to level 5 in response to a train of eight relay A remains energized after receiving the impulses, relay J operates when relay C releases,

the circuit for operating relay J being traced through brushes VW andiifth ofi-normal vertical back contacts, contact c3 and contact h3. Relay J locks through contacts :il and b3. Rotary magnet RM is now automatically operated in a circuit through the front contact of orfnormal spring nl, contact i2, interrupter contacts of magnet RM, and through contacts hl and ti to ground. The brushes are advanced by magnet RM to the eleventh rotary position of level` 8 and then drop to the normal level. When the shaft reaches normal, the circuit for operating magnet RM is opened at the oinormal spring ni; and the closure oi oit-normal contact n3 completes a circuit, which includes contact 7'3, for operating relay H. Relay I-I locks through contacts h2 and bil. The next train of impulses consisting of more than three impulses is effective to select one of tlie vertical levels l to l, inclusive, as hereinbefore described. The first three impulses of the digit are absorbed so thatthere is amgple time cr the switch to be returned to normal before the fourth impulse is received and the switch begins its vertical movement. And the next succeeding train of impulses received by relay A eiects the operation ci rotary-stepping magnet RM and advance of the brushes to a desired set of terminals in the selected level.

If, instead of absorbing the digit 8, it is desired that there be both selective and hunting movements on level 5, relay J is provided but contact spring ti is not connected to ground. In this case brush RW is used to effect the advance of the brushes over any selected group of terminals in level 5 until an idle set of terminals is engaged or the last set o-i terminals in the group is reached. When relay J operates, magnet RM` is connected through contacts nl, i2, interrupter contacts of magnet RM, contacts hl, ti and c5 to brush RW; but, the normal terminal being free of ground potential, magnet RM is not operated until relay A responds to the next set of digit impulses. The operation of magnet RM in response to these impulses advances the brushes to the rst terminal or the desired group in level t; whereupon, when relay C releases, magnet RM is operated through brush RW and the grounded terminals oi the group. Relay J being operated the test circuit through relay T and brush TW is closed at contact it so: that relay T operates as soon as an idle set of terminals is reached. Ii the brushes are advanced to the last set of terminals in the selected group, magnet RM cannot again reoperate since brush RW finds no ground potential on the last terminal of a group.

Other variations and modifications of the switch may be made without departing from the spirit of the invention.

What is claimed is:

l. In an automatic telephone system, a selector switch comprising a set of brushes, a bank of terminals, and a stepping magnet for advancing the brushes, an imrpulse relay associated with said switch for receiving directive impulses from subscribers impulse senders, circuit means controlled by said relay in response to a train oi more than a certain number of impulses from` a subscribers impulse sender for absorbing said certain number of the impulses without movement oi the brushes and for operating said magnet in response to the succeeding impulses of the train to eiiect a desired selective movement of the brushes.

2. In a combination according to claim l, circuit mleans rendered effectiveafter receipt of a first train of impulses by said impulse relay for preventing the absorption of any impulse of the next train received by said impulse relay.

3. In combination, a selector switch comprising a vertical-stepping magnet, a rotary-stepping magnet, a set of' brushes and an associated bank of terminals, an impulse relay responsive to directive impulses, circuit means controlled by said impulse relay for absorbing one or more impulses of a train received by said impulse relay without movement of the switch out of normal position and effective in response to succeeding impulses in the same train for causing the operation of said vertical-stepping magnet to select a desired level of the terminal bank, and circuit means including said rotary-stepping magnet eiective in response to the next succeeding train of impulses received by said impulse relay to select a desired set of terminals in the selected level.

1i. In combination, a selector switch comprising a stepping magnet, a set of brushes and an associated bank of terminals, an impulse relay responsive to directive impulses, circuit means controlled by said impulse relay for absorbing a rst train or impulses of not more than a predetermined number o like directive impulses without movement oi the brushes of the switch and for absorbing said predetermined number of impulses of a train consisting of more than said predetermined number of like directive impulses and for causing the operation of said verticalstepping magnet in response to the succeeding irnpulses in the train, and circuit means effective ii no movement of the switch results from the rst train of impulses received by said impulse relay for causing the operation oi said verticalstepping magnet in response to the next succeeding train of impulses received by said impulse relay.

5. In combination, a selector switch comprising a vertical-stepping magnet, a rotary-stepping magnet, a set of brushes and an associated bank of terminals, an impulse relay responsive to directive impulses, circuit means controlled by said impulse relay for absorbing a first train of irnpulses of not more than a predetermined number or impulses without movement of the brushes ofthe switch and for absorbing said predetermined number of impulses of a train consisting of more than said predetermined number oi irnpulses and for causing the operation of said vertical-stepping magnet in response to the suc- '1 ceeding impulses in the train, circuit means eifective if no movement of the switch results from the iirst train of impulses received by said impulse relay for causing the operation of said vertical-stepping magnet in response to the second succeeding train of impulses received by said impulse relay, and circuit means effective in response to the first train of impulses received by said impulse relay following a vertical movement of the brushes for causing the operation of said rotary-stepping magnet.

6. In a combination according to claim 5, circuit means efiective if the level selected by the vertical movement oi the switch is a particular level for rendering the rotary-stepping magnet automatically operative to advance the brushes to hunt for an idle set of terminals in the selected level.

7. In a combination according to claim 5, circuit means effective following a directive rotary lay, circuit means including said rotary-stepping magnet for thereupon advancing the brushes automatically beyond selected level to cause the return of the brushes to normal position, and circuit means for absorbnormal position before the vertical-stepping magnet is again operated.

10. In a selector switch having a primary magcertain number.

l1. In a selector switch rcuit ESMOND PHILIP GOODWIN WRIGHT.

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