US1840090A - Impulse circuit - Google Patents

Description

Jan. s, 1932. C, L GOODRUM 1,840,090

IMPULSE CIRCUIT Filed July 31, 1930 winding of' the magnet.

Patented Jan. 5r, 1932 CHARLES L. YGOODRUJYYI, 0F NEW YORK, N. Y., TORIES, INCORPORATED, OF NEW YORK,

ASSIGNOR TO BELL TELEPHONE LABORA- NfY., .A CORPORATION OF NEW YORK IMIULSE CIRCUIT Application led July 31,

This invention relates to impulse circuits and particularly to those employedin the operation of switches for telephone systems.

The objects are to improve the operating conditions of holding relays, to render these relays less liable to release while impulses are being received, to render the adjustments of these relays easier to meet, and to otherwise improve the effectiveness and reliability of impulse circuits.

Heretofore it has been the usual practice' to arrange the impulse circuits of step-bystep switches suoli that the holding and re-` lease relay receives its operating energy over a circuit closed through the front contact of the impulse relay. Since the impulse relay releases and operates successively in response to a series'of impulses, the circuit of the holding relay is opened on each successive impulse from the time the impulse relay opens its front contact until this contact is again closed. To prevent it from retracting its armature during these openings, the holding relay is constructed so asto release slowly.

f" However, it has been found that unless the relay is properly adjusted it will lose enough energy on a long series of impulses to release, thus causing improperoperation of the apparatus.

According to the present invention, these defects are overcome by means of an arrangement in which the holding relay receives energy from two separate circuits, one of which is closed over a front. contact and the other of which is closed overa back contact of the impulse relay. With the impulse Vrelay energized, theholding relay is maintained operated over the usual circuit extending through the front contact of the impulserelay. Each time the impulse relay releases its armature to deliver .impulses to the vertical stepping magnet, a circuit is closed over the back con# tact of said relay through a second winding on the holding relay and'thence through the The holding relay receives energy in this circuit until the vertical magnet has partially operated, at'which time the second winding ofthe holding relay is shunted. v

The advantage of this circuit arrangement lin the usual manner to set its 1930. Serial No. 471,909.

is that the holding relay receives energy over both front and back contacts of the impulse krelay and,\therelore, will not accidentally release while impulses are being received, whether the series consists of a. few impulses or the maximum numberr of impulses.

In the drawings Fi g. 1 represents a portion of an automatic telephone system in which the circuits for one of the selector switches are shown in detail, other equipment being illustrated diagrammatically. Figs. 2 and 3 show alternative circuit arrangements.

`Considering Fig. 1 first, a subscribers line 1 appears at the central oflice in a suitable switching device such as a line finder F. Vhen the line calls, the finder F is operated brushes 3, 4 and 5 on the terminals of the line 1, thereby extending said line to a selector switch such as the selector S having'the brushes 10, l1 and 12. As soon as the subscribers line is extended to the selector S, a circuit is closed for the impulse relay 13 and may be traced from battery, through the left-hand winding of said relay, inner upper back contact of relay 9, conductor 7 brush`4, thence over the loop of the calling line and returning through the brush 3, conductor 6, uppermost back contact of relay 9, right winding of relay 13, contacts 2l, through the secondary winding of the tone coil 22 to ground. The relay 13 operates and closes an energizing circuit for the holding relay 14. This circuit may be traced from ground, through the lowermost contact of relay 9, front contact of relay 13, upper Winding of relay 14 to battery. The relay 14, which controls the release of the switch S-,is designedwith a slow-release characteristic in lorder that it will maintain its armatures in their attracted position during the intervals that itis de` prived of'energizing current while impulses are being received.

lThe coil 22 causes a tone to be transmitted to the subscribers substation Vto notify him that impulses may be transmitted. In response to this tone, theV subscriber manipulates his dial Q. to send a series of impulses representing a digitalplace in the wanted designation. On the first opening ofthe subscribers line by the impulse transmitter 2, the impulse relay 13 releases its armature, lirst opening its front contact and immediately thereafter closing its back Contact. The opening olf the trent contact of relay 13 results in 'the opening o' the energizing circuit oi? the holding relay 1l, and this relay eonnneneei-I; to lose energy. However, due to its slow-releasing characteristic, it will retain its armatures. Relay 13 at lits baci; contact closes a circuit for delivering the linst impulse to the vertical stepping magnet 16. This circuit may be traced from ground, through the lowermost contact ot relay 9, back contact et relay 13, inner front contact and winding ot holding relay 114-, winding olf relay 15, winding of the magnet 16 to battery. Current flowing in this circuit energizes the relay 15 and the vertical magnet 16 which attracts its armature to move the brush sha'tt one vertical step. T he relay 15 is slow to release and maintains its armature attra0ted during a series ot impulses. Since the lower winding ot the holding relay 111 is also included in series with the magnet 16, additional energy is supplied to the relay 111 to replenish the energy lost during the momentary opening of its original energizing circuit. The magnet 16 also closes the contact shown and in so doing shunts the lower winding ot' the holding relay lll. The shunt circuitmay be traced from ground, through the lower armature of relay 9, back contact of relay 1?), inner contact ot relay 111, contact of' magnet 16, thence through the windings oi': relay 15 and magnet 16 to battery. rfhe contact of the magnet 16 is so adjusted that it closes slightly betere the vertical pawl seats .itselt in the ratchet on the brush shaft. The purpose ot' this will be explained more in detail hereinafter. 'if he closure ot the shunt around the lower winding of relay 1K1 tends to maintain the fini; in that winding so that the energy is not dissipated imme-4 diately. The vertical magnet 16, continuing its stroke in the circuit which now excludes the lower winding ot the relay 14;, advances the brushes to a full step.

As soon as the switch takes its first vertical step the contacts 2() are closed, and relay 17 energized in a circuit from battery, through its winding, upper contacts 20, closed contacts of relay 15, conductor 25 to ground at the lower contact of relay 111. Relay 17 operates and locks in a circuit from battery, through its winding, upper contacts 20, con tact of the rotary magnet 18, upper contact ot relay 17, conductor 26 to ground at the lowermost contact of relay 9.

At the end of the first impulse, the line is again closed., and relay 13 operates to shift its armature from the back contact to the front contact. Relay 14 is now again supplied with energy over its upper winding,

" and the energizing circuit ot magnet 16 and relay 5 is temporarily opened. Magnet 16 immediately releases its stepping armature and also opens its contact, removing the shunt 'from the lower winding o't the relay 1d. For each succeeding impulse in the series, the relay 13 releases and delivers an in'ipulse to the magnet 16 over a circuit which extends lirst through the lower winding of relay 1st and then in shunt ot' said winding, through the relay 15 and the winding ot the magnet 16. ln this manner the switch stepped vertically to the proper level, and during the stepping operation relay lll1 is successively supplied with energy through its upper and lower windings.

At the end of the impulse series, the line is re-closed for a long interval., and relay attracts and holds its armature against the front contact. After an interval, relay 1o releases its armature and in so doing prepares an energizing circuit tor the rotary magnet 18 to advance the brushes 10, 11 and 12 over the contacts ot the selected group. The circuit tor the magnet 1S may be traced from battery through the winding of the magnet, lower contact of relay 17, normal contacts of relay 15 to the grounded conductor 2 The magnet 18 energizes and steps the brushes onto the lirst set of contact-l, .n the group. Magnet 18 also attracts its armature and opens the holding circuit oil relay 1T. Relay 17 immediately releases and opens the energizing circuit o1 the magnet 18, whereupon the magnet releases preparatory to taking the next rotary step. li the circuit appearing in the iirst set ot contacts is busy, the test brush 12 encounters a ground potential on the test terminal, and the relay 17 is reenergized in the following circuit: Battery, through the winding of? said relay, pper contacts Q9, normal con tacts ot magnet 1S, conductor 2T, inner lower back contact oit relay 9, conductor 2S to the grounded test brush 12. A parallel circuit may be traced from battery, through the winding ot relay 17, rpper Contact 20, contact oil the magnet 19, conductor 27, winding et switching relay 9, upper contacts 21 to the ground ed ctmductor 25. Since there is a direct ground potential on the brush 19, relay 9 is shunted and does not operate. Relay 1T in operating rocloses the circuit of the magnet 18, which advances the brushes another step and opens the circuit ol rela-y 17. Relay 1T releases, in turn releasing the magnet 18. This action continues until the test brush 1i! encounters an idle terniinal, which is represented by the absence olI ground potential. At this time, the shunt is removed from the winding ot' relay 9, and said relay immediately energizes. Relay 17, however. does not energize .in this circuit due to the rcsistance ot relay 9; accordingly the circuit ot the stepping magnet 18 is maintained open,

and the switch ceases to advance, coming to rest on the terminals of the idle circuit.

Relay 9 in operating switches the tip and ,ring conductors of the circuit through the brushes 10 and 11 and thence to the next sucrelay 9 energized. J

, cuit for the release ceeding switch. Relay 9 by attracting its armatures opens the circuit of relay 13 which releases its armature. After an interval, ieflay 14'releases since no current flows through 5 either its upper or lower windings. Before relay 14 can release to remove ground fromA When it is desired to release the selector S, groundpotential is removed fromthe conductor 28, thereby permitting the release ot' relay 9. Relay 9 closes an energizing cirmagnet 19 traceable from battery, through the winding of said magnet, lower contacts 20, inner back contact of relay 14, back contact of relay '13, lowermost contact of relay 9 to ground. The r-e- ^lease magnet 19 energizes and releases the "switch S. When the switch fully restores, the vertical off-normal contact 20 is opened, and the magnet 19 deenergizes.

The condenser Q9 and lresistance 30 are provided for the purpose of protecting the *Contact of relay 13 during the vertical pulsing operation and the lower contact of relay 17 during the rotary steppingmovement. The lower plate of the conductor 29 is conn nected in parallel with the impulse circuit extending to the verticaly magnet 16, and the upper plate of said condenser is connected in parallel with the impulse circuit of the rotary magnet 18. f

Should the subscriber abandon the call betore transmitting impulses to the switch, relay` 13 releases, closing the circuit hei-einbefore traced through the lower Winding of relay 14, winding of relay 15 and winding of magnet 16 to battery. The magnet short-circuits the lower winding of relay 14, and, since the upper winding is deenergized, the relay releases after an interval causing the restoration of the switch. Should the subscriber abandon the call durinO'V the rotary' movement of the switch, relay 13 releases and completes a circuit fromground through the lowermost contact of relay 9, back contact of relay 13, thence as traced through the windings of relays 14 and 15 and the magnet 16 to battery. Inasmuch as the brushes of the switch are now in the level of terminals,

the magnet 16 will not be able to advance its stepping dog a full step. Since, however, the magnet closes its contact just before the stepping dog is fully seated in the vertical and the inner lower ratchet, the lower winding of the relay 14 is certain to be short-circuited under these conditions. Therefore, after an interval the relay 14 deenergizes and closes the release eircuit to restore the switch to normal.

Figs. 2 and 3 illustrate modiiications of the pulsing circuit. lnFig. 2, a rotary off-normal contact 23 is provided and opens as soon as the switch has taken its iirst rotary step. ln Fig. 3, the rotary oil-normal contact 24 closes as soon as the switch has taken is first rotary step. By providing these rotary offnormai contacts, it is possible to adjust the contact on the vertical magnet 16 so that it closes later in the stroke, namely, just about the time the magnet has completed the full forward movement of the shaft. With the circuit shown in Fig. 2, should the subscriber abandon the call during the rotary movement,

no impulse can be delivered to the vertical magnet 16, and consequently current is not caused to tlowptl rough the lower relay 14 due to the fact tl e contact 23 is open.Y After an interval therefore, the holding relay 14. releases and causes the restoration of the switch. Similarly in Fig. 3, should the subscriber abandon the call during the'rotary movement, an impulse is delivered to the vvertical magnet, but, sincethe contacts 24 are closed, the lower winding of relay 14 is shunted and consequently this relayis not held energized by reason of its lower winding. The circuit for the magnet 16 in this case extends through the armature and contact of relay 14, contacts 24, winding of the magnet 16 to battery.

The finder F and the selector switch S disclosed in this application. may be of any suitable construction. Selcctor S is preferably of the two-movement step-by-stepA type, having a first stepping movement to select groups of trunks or lines and a second stepping movement to select individual trunks or lines. A switch ot' this general character is disclosed in the patent to Keith et al. No. 815,- 876, granted March 13, 1906.

lVhile the invention has been illustrated in connection with a specific circuit .arrangement, it is to be understood that it is not limited to these particular circuits. It should also be noted that this invention is applicable to repeaters for repeating impulses from an incoming circuit to an outgoing circuit and that it is also applicable to connector switches in which both the primary and secondary movements are directively controlled by impulses. y

What is claimedis:

l; The combination in an impulse circuit of an impulse relay, a stepping magnetre-` sponsi've toimpulses delivered by said relay,

a holding relay, -a circuit including the front contactof the impulse relayfor supplying energy to 'said holding relay, and a circuit winding ot including a back contact of the in'ipulse relay 'for supplying energy to said holding relay.

2. 'Ihe combination in an impulse circuit of an impulse relay, a source of current, a.

l holding relay, a circuit closed b 'T said im- 'pulse relay when energized for supp lyin current from said source to the holding relay, .and a circuit closed by said impulse relay when released 'lor supplying current from plying energy to said holding relay.

3. In combination, an impulse relay, a holding relay, a circuit including the Yl'ront contact ol" the impulse relay lor supplying energy to said holding relay, and a circuit including a back contact or the impulse. relay and a contact of the holding relay Alor supplying energy to said holding relay.

si. In combination, an impulse relay, a stepping magnet responsive to impulses delivered by said relay, a control relay, ya circuit including the iront contact or the impulse relay for operating said control relay, and a circuit including the back contact oif the impulse relay for supplying.energyto said control relay and for delivering an nnpulse to said magnet.

In combination, an impulse relay, a stepping magnet responsive to impulses, a control relay, a circuit including the iront contact of the impulse relay for operating said Control relay, a circuit including a back contact of the impulse relay 'for delivering operating impulses to said magnet, and a winding for the control relay in said last mentioned circuit.

6. In combination, an impulse relay, an operating magnet responsive to impulses delivered by said relay, a control relay, a circuit closed by the front Contact of the impulse relay or operating said control relay, a circuit including a back contact of the impulse relay and a contact on the control relay for delivering impulses to said magnet, and means in said last mentioned circuit for supplying energy to said control relay.

7. In combination, an impulse relay, a holding relay having two windings thereon, a circuit closed at a front Contact o the impulse relay for energizing one of said windings, and a circuit closed at the back contact ot said impulse relay and a front cont-act of said holding relay for energizing the other of said windings.

8. In combination, an impulse relay, a stepping magnet, a holding relay having two windings, a circuit closed at the front contact of the impulse relay for energizing one of said windings, and a circuit closed at the back contact of said impulse relay for energizing said stepping magnet and the other of said windings. Y

9. The combination in an impulse circuit of an impulse relay, a stepping magnet responsive to impulses delivered by said relay, a holding relay, a circuit including the front Contact of the impulse relay for supplying energy to said holding relay, a circuit including a back Contact of the impulse relay for supplying energy to said holding relay, and means controlled by said magnet for pre venting the `further supply of energy in said second circuit to the holding relay.

lO. The combination with an impulse relay oi a stepping magnet responsive to said relay, a holding` relay, a source or' current, a circuit closed by the 'front Contact of the impulse relay for supplying current to the holding relay from said source, a circuit closed by the back contact of the impulse relay for supplying current to the holding relay from said source, and means controlled by said magnet for shunting the current in said second circuit awa-y from said holding relay.

11. The combination in an impulse circuit of an impulse relay, a stepping magnet responsive to impulses from said relay, a hold ing relay having two windings, a circuit closed by the 'liront Contact of the impulse relay for one of said windings, a circuit closed by the bach contact or' the impulse relay for the other of said windings, and contacts closed by the operation or'. said stepping magnet for short-circuiting said second winding.

12. In combination, an impulse relay, a holding relay having slow-to-release characteristics, a circuit including the :iront contact oit the impulse relay :tor supplying energy7 lo said holding relay, and a circuit including the back contact of the impulse relay, and a contact of the holding relay for supplying energy to said holding relay.

lil. In combination, an impulse relay, a stepping magnet responsive to impulses delivered by said relay, a control relay having slmv-towrelease characteristics, a circuit including the front contact of the impulse re lay for operating said control relay, and a circuit including the back contact olf the impulse relay for supplying energy to said con* trol relay and ior delivering an impulse to said magnet.

In witness whereof, I hereunto subscribe my name this 28th day of July, 1980.

CHARLES L. GOODRUM.

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