US1882851A - Telephone system - Google Patents

Description

Oci- 18, 1932- w. H. MATTHIES 1,882,851

TELEPHONE SYSTEM Filed Oct. l5, 1931 /NVENTOR W H. MA 7TH/E 5 Afro/mfr Patented Oct. 18, 1932 Unirse stares earner orties WILLIAM I-I. MATTI-HES, OF HACKENSAGK, NEEV JERSEY, ASSGNOR 'EJO BELL TLPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION O F NEW YORK TELEPHONE SYSTEM Application filed October 15, 1931. Serial No. 568,927.

This invention relates to automatic telephone systems in which switching apparatus is controlled to establish connections under the control of a subscribers impulse dial.

The invention has been disclosed as applied to the impulse receiving circuit of a common register sender in Which registers are provided which are successively set in response to series of impulses dialed by a calling subscriber, such registers being instrumental in controlling the setting of tne sel ctor switches to establish a telephone connection from the call ing' subscribers line to the line Whose designation the calling subscriber has caused to be registered on such registers. Obviously, the invention is also applicable to selector switch circuits of the types Which are set directly by dia-led impulses rather than through the intervention of a common sender.

Since a common sender may be taken into service by any one of a large number of subscribers lines7 it will be apparent that the dialing loops which may be established between the subscribers subst-ations and the impulse responsive relay of the sender vT'ill vary considerably in length and consequently in resistance. An impulse responsive relay which Will operate satisfactorily over long loops of relatively high resistance, that is, release quickly each time the loop circuit is opened at the contacts of the subscribers dial, Will not operate as Well over short loops of rela-tive low resistance, since with the lower resistance, the relay will receive more current and its magnet core will become saturated to a. point which will render the rela-y sluggish to release on circuit openings. @n the other hand an impulse relay which will operate satisfactorily over short loops of relatively loW resistance, will not operate as Well over long loops of relatively high resistance, since with the higher resist-ance the relay will not receive suiiicient operating current between loop openings to properly saturate its magnet core and Will thus release too quickly. To render the `innrulse relay operable under such Wide operating conditions requires a very careful eesign and adjustment of the relay. It is therefore the object of the present invention to obviate the aforementioned difficulties by providing for the automa-tic Aadjustment of the responsiveness of the impulse relay so that when an impulsing loop is established thereto of less than average resistance, the impulse relay is rendered less sensitive than when an impulsing loop of more than average resistance is established. Thereby the impulse relay performs more uniformly regardless of the resistance of the connected impulsing loop.

In accordance with the present invention this object may be attained in several Ways. In one embodiment of the invention a normally shunted resistance and the opera-ting Winding of a marginally adjusted relay are connected in series with the Winding of the impulse responsive relay in one leg of the impulsing loop. The shunt of the series resistancenormallyextends through contactsof the marginal relay. Should a line be connected to complete an impulsing loop of more `than average length through the Winding of the impulsing relay, the resistance of such loop Will be high enough to prevent the operation of the serially connected marginal relay. Should however, a. shorter loop be established of less than average length and consequently of lower resistance. the current flowing thereover will be of sufficient strength to operate both the impulse responsive relay andthe marginal relay. The marginal relay upon operating Will first establish a locking circuit for itself and Will then remove the shunt Afrom the series resistance thereby increasing the resistance of the loop. By this means the resistance of short loops is increased to Ysubstantially the resistance of the longer loops and the impulse responsive relay is therefore always operated over loops having a smaller variation in resistance.

lf a. closer adjustment of loop resistance is found to be desirable, a plurality of resist.- ances and differently margined relays may be employed in series with the impulse responsive relay, the margins of such relays being so selected that the shorter the connecting impulsing loop is, the more compensating resistance Will be added in series with the impulse responsive relay. Y

In accordance with a furtherembodiment CTL of the invention, the impulse responsive relay may be normally biased by a dii'erentifl winding connected into a biasing circuit through a resistance, and the marginal relay connected in series with the operating winding of the impulse relay may be arranger when it operates over a low resistance impulsing loop to short circuit the resistance, thereby increasing the bias of the impulse relay. Thus, when the impulse relay is connected into a. long iinpulsing loop, it is less biased than when it is connected into a short loop.

For a more complete understanding` orn the invention reference may be had to the rollovfing details description talren in connection with the accompanying drawing in which Fig. 1 shows diagrammatically a subscribers line, a line finder-district selector trunl; circuit and such portions of a common sender as are necessary to disclose the invention;

Fig. 2 shows a modification of the invention by means of which a finer compensation of resistance in the dialing loop is attained; and

Fig. 3 shows a further embodiment oi the invention.

Referring to Fig. 1 of the drawing, a subscribers substation of an automatic telephone system is disclosed at 100 having `the usual impulse dial 111. In response to the removal of the receiver at the substation 100 for initiating a call, the calling line becomes eX- tended by line finder 101 to the trunlr circuit 102 terminating in the district selector 103 and by the usual link circuit, not shown, to the common sender disclosed in the dot and dash rect-angle 104. Following the connection of the calling substation 100 with the sender 104 an impulsing loop is established from battery through the impulse responsiv relay 105, the left winding of marginal relay 106, the left normal contact of rela-y 106, conductor 107, the upper contacts ol" cam 106, brush 109 and terminal 110 of line finder 101 over the substation loop through the dial 111, terminal 112 and brush 118 of the line finder 101, lower contacts of cam 1111-, conductor 115 to ground through the winding ot coil 116. Impulse responsive relay 105 operates over this circuit and closes a circuit lor the slow-to-release relay 117 in the usual manner.

It will iirst be assumed that the substation 100 is connected over a long line loop orn high resistance with the sender 104 and that consequently the marginal relay 106 does not receive suflicient current to operate. Resistance 118, therefore, remains shunted at the left Contact ot relay 106 and relay 105 receives the maximum possible operating current. Upon the operation and release of the dial 111 the impulse loop is interrupted in the usual manner to thereby cause the impulse responsive relay to release and operate.

W hen the relay 105 releases upon the initial opening of its circuit, a circuit is established tor relay 119 which in turn closes the circuit of relay `120. Relay 120 operates and locks to od-normal ground and closes a shunt around the left winding of relay 106 to remove its impedance Jlfrom the impulsing loop. In view of the fact that the resistance of a long loop may be high enough to prevent the impulse relay from receiving a suilieiently high enough saturation, a branch of the impulsing loop is also extended from conductor 107 through condenser 121, resistance 122, back contact of relay 106 to off-normal ground for the purpose of shuntinO the winding oi the impulse relay 105 when connected to long, high resistance loops thereby slowing up the release of the impulse responsive relay 105.

Should the sender become connected to a subscribers line over a short loop having low resistance, marginal relay 106 will become energized as well as impulse relay 105. Relay 106 upon operating tiret operates its right armature to close a locking circuit through its right winding 'from off-normal ground and to disconnect the branch ol' the impulsing loop through condenser 121 and resistance 122. Thereafter relay 106 opens its left contacts to remove the shunt from resistance 118. Resistance 118 is now included in the impulsing loop thereby increasing the resistance of the loop to a point more nearly commensurate with the resistance of the longest loops.

ln 2 a modification of the invention is disclosed similar to Fig. 1 except that an additional marginal relay 123 and an additional resistance 124 are provided. The marginal relays 106l and 123 have ditl'erent operating margins. TWhen the sender becomes connected t0 a subscribers substation over a long line the current flowing through the operating windings of relays 106 and 123 is not sulicient to operate either of them. lf a line oi medium length is connected, relay 106 will operate but relay 123 will not and therefore resistance 118 is included in the impulsing loop. If a short line is connected both marginal relays 106 and 128 will operate thereby including both resistances 118 and 124 in the impulsing loop. Thus compensation is made for lines of three average lengths. It will be obvious that a closer compensation might be obtained through the use of additional marginal relays and serially connected resistance units. rlhe impedance of relays 106 and 123 may be removed through the operation ol relay 120 as described in connection with Fig. 1.

ln accordance with the modification disclosed in Fig. 3 the impulsing loop at the sender includes the operating winding ot a marginal relay 106 and the operating winding oi' impulse responsive relay 105. he impulse responsive relay 105 is provided with a biasing winding connected in circuit with a resistance 125. rllhe two windings of relay 105 are dierent-ially wound so that iii) L circuits ol lower resistance viliei ing winding is connected in circuit with resista -ce 125 it is not biased to such an the* extent as 'to prevent it from responding quiclly to dialed impulses. When the sender is seized over a short loop oic low resistance relay 106 operates and locks to oli-normal ground and at its left contact shunts the resistance 125 thereby increasing the current i'iowing through the left biasing winding of relay 105. Relay 105 is now more heavily biased and will not become over-saturated by the stronger current flowing over the short line loop. li" desired a shunt path through a condenser and resistance such as is disclosed in n ig. 1 could be employed controllable over a a ci; Contact of marginal relay 106.

is previously stated the inventio., is not to be construed as limited in its application to the impulsing circuit of central ofiice senders since itis equally applicable to the impulse responsive circuit of switches of the tyl e vvhicl respond directly to impulse dialed by callin i subscribers.

What is claimed is 1. ln a signaling system, a responsive dev'ce, means c; establishing operating circuits of diiierent resistance to said resnonsive device, means operative over said circuits :for determining whether a particular circuit is of relatively high or low resistance, and means controlled by said means for rendering said responsive device less responsive it said circuit is found to be of 10W resistance.

2. ln a signaling system, a responsiveA device, means for establishin operatin circuits of dilterent resistance to sain responsive device, and means independent of said responsive device operative over said circuits for automatically che.. resistance of d circuits whereby the resis `ce of all of l said circuits is more nearly equa.. ln a signaling; sv in, a r vice, means igor establishio cuits to said device, the csistai of said circuits being` lower th i adding resistance thereto whereby the resistance ci il of said circuits is more nearly equalized.

4. ln a signaling svstem, a responsive device, means for establislii cuits to said device, the r ci said circuits bein si' operating?,l cir- Y of certain 'lower (e connected in series with said responsive defi operative only ov r the circuits or stance 'for adding i'csistaceto said ra'lit of substatlons a responsive devicev means for establishing an operatingcircuit t said device from any ol said substations,saici operating circuits having diierent resistance in accordance with 'thc distance of said substations from said devi e, means independent or said responsive device operative only over such circuits as have relatively low resistance for adding resistance thereto whereby said responsive device is always operable over circuits of more nearly equal resistance. n

G. In telephone exchange system, a plurality of substations, a responsive device, means lor establishinel an operating circuit'to said device from any of said substations, said operating circuit-s having different resistance in accordance with the distance of said substations from said device,and a marginal relay associated scries with said responsive device andoperative only over 'the circuits of relatively low resistance for adding resistance thereto whereby said responsive device is always operable over Lcircuits of more `nearly equal resistance.

7. In a telephone exchange system, a plurality of calling line substations, each having an impulse dial, an impulse vresponsive relay common thereto,Y means for establishing an operating circuit to said relay from any of said substations, said operating circuits having dillerent resistance in accordance with the distance of said substation from said relay, and marginally adjusted mea-ns associated in series with said relay and operative only over the circ -its of relatively low resistance for adding resistance thereto whereby said relay ance with the distance or" said substations from said relay, and a marginal relay associated in series with said relay and operable only over the circuits of relatively low resistance for adding resistance thereto whereby said impulse relay is always responsive to dialed impulses over circuits of more nearly equal resistance.

0. In a signaling system, a responsive device, means itor establishing operating circuits to said device, the resistance of certain or" said circuits being lower than the vresistance of other oi said circuits, a normally shunted resistance, and a marginal relay connected in series with said responsive device, said marginal relay operative only over the VEl() ing an operating circuit to said relay from any orp said substations, said operating cir' cuits having different resistances in accordance with the distance of said substations from said relay, a normally shunted resistance and a marginal relay connected in series with said impulse relay, said marginal relay operable only over the circuits or relatively low resistance, contacts controlled by the operation of said marginal relay for removing the shunt from said resistance whereby the resistance or" all of said circuits is more nearly equa-lized.

ll. In a signaling system, a responsive relay, means for establishing operating circuits to said relay, the resistance of certain of said circuits being lower than the resistance of other of said circuits, means normally in shunt of said responsive relay Jfor rendering it sluggish to release, and means operative only over the circuits or" lower resistance for removing said shunt.

l2. In a signaling system, a responsive relay, mea-ns for establishing operating circuits to said relay, the resistance of certain of said circuits being lower than the resist-v ance of other of said circuits, a circuit oomprising a condenser and resistance normally in shunt of the Winding of said relay, and means operative only over the circuits of lower resistance for opening said shunt circuit.

13. In a signaling system, a responsive relay, means for establishing operating circuits to said relay, the resistance of certain of said circuits being loiver than the resistance of other of said circuits, acircuit comprising a condenser and resistance normally in shunt oi"- the Winding oi` said relay, and means operative only over the circuits of lower resistance for opening said shunt and for thereafter adding resistance to the operating circuit or" said relay.

In a telephone exchange system, a plurality of calling line substations, each having an impulse dial, an impulse responsive relay common thereto, means for establishing an operating circuit to said relay from any of said substations, said operating oircuits having different resistances in accordance with the distance of said substations from said relay, a circuit comprising acondenser and resistance normally in shunt of the Winding of said relay, a normally shunted resistance and a marginal relay connected in series With said impulse relay, said marmy name this 13th day of October, 1981.

WILLIAM H. MATTIIIES.

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