US1821086A - Telechronometer - Google Patents

Description

G. BABCOCK TELECHRONOMETER Sept. l, 1931.

Original Filed Oct. 15, 1921 Patented Sept. 1, 1931 UNITED STATES PATENT OFFICE i, e

GARRISON BABCOCK, OF SEATTLE, WASHINGTON, ASSIGNOR TO AMERICAN TELECHRO- NOMETER COMPANY, OF SEATTLE, IVASHINGTON, A CORPORATION 0F WASHINGTON TELECHRONOMETER Original application filed 0ctober15, 1921, Serial No. 508,037. Patent No. 1,747,210, dated February 18, 1930. Divided and this application led April 6, 1929. Serial No. 352,983.

This invention relates to telechronometers, more particularly to a new and improved telechronometer for use on a telephone line.

In my copending application, vSerial No. 508,037, filed October 15, 1921, Patent No. 1,747,210, Feb. 18, 1930, of which application this case is a division, I disclose a telechronometer and a telephone system employing that telechronometer. For the full operating details of such a system, reference is here made to the above copending application.

Briefly, however, the telechronometer comprises an electromagnetic meter located at the subscribers premises and operated by reversals of current `over the subscribers line to the telephone office at periodic intervals during the conversations over the telephone.

The telephone comprises the usual talking instrumentalities and may be either a manual telephone or an automatic telephone depending upon the system with which it is used.

The telechronometer itself, which is disclosed in detail in the above mentioned copending application, comprises a plurality of dials over which creep register indicators which are driven by a ratchet and gear arrangement actuated electro-magnetically by the reversal of the polarity of current flowing over the telephone line.

To bring about this reversal of current, a reversing switch or pole changer is located in the central office and associated with the battery feed leads of the cord circuit, in a manual exchange or of the line relay of the connector or final selector switch of an automatic telephone exchange. Briefly,` this pole changer comprises a plurality of resistance units, preferably four in number, which are operated in pairs to periodically reverse the polarity of the battery connection to the answering supervisory relay of the cord circuit. The battery feed for the transmitter of the calling station is drawn through this relay as will be well understood by those skilled in the art. The resistance units are of the type which vary responsive to the change of pressure upon them and might conveniently be carbon pile resistors. When the pressure on the pile is increased the resistance decreases and the current How correspondingly increases. The driving arrangement for the plungers which alternately compress and decompress theY resistance piles is arranged so that while one of the pairs of resistances is being compressed the other one is being decompressed in the same ratio. .The battery supply leads ofthe line relays are connected to bot-h of ance values of the two pairs of resistances effects a change in polarity of the connection in the manner explained in detail in my above mentioned copending application.

Inasmuch as the registering mechanism is located at the subscrihers premises, it is desirable that the meter be sealed and protected to prevent unscrupulous subscribers from disabling it Vto thereby reduce their telephone bills. K

The sealing of the meter-hasbeen `ern- Y ployed heretofore to prevent tampering with this mechanism, and while that seal is eective for that purpose, it does not guard against the contingency of the subscriber shouf-circuiting or grounding the electromagnets of the meter to thereby prevent its operation. v y

In telechronometers devised heretofore the electro-magnets of the meter were in the line circuit only during conversation and then in such a manner that the detection of a short circuit or a ground connection by tests supplied at the central office was very difhcult. f

Inmy present invention which is based upon the disclosure of the above copending application, I have provided a new and improved electro-magnetic circuit for the telefA chronometer, which circuit lends itself to the ready detection of circuit tampering by the subscriber to prevent the operation of the telechronometer.

The electro-magnet of the telechronometer comprises two windings which are serially connected in the line circuit. The windings are so designed that when the normal line circuit current is flowing through either one of them, the meter will be operated. That" QG() these rhecstats so that the change in resistcuit to the telephone office is balanced-elec-y trically.`

Iiftlie subscriber short circuits one `ofthe windings of the meter, the electrical circuit 1s unbalanced, and the detection of that;

short circuit is made readily possible by the reduced resistance and inductance of the,

line circuit.. The short circuiting of the one winding will not prevent the operation of the metery since the remaining winding is of sufficient' 'strength` to fully operate the telechrenometeruna-idedl If-the subscriber short circuits both o'- the windingsot'V the meter, ofv course it cannot beoperated, but the reduction of' the impedance ot the telephone circuit' caused by this short circuit increases thel current suppliedto the circuit and thereby mak-es the detectionof the shortcircuit readily possible by the use of 'the usual and well known testinginstrument atthe command of the wire chiefj at the central olice.

In theidrawing I' have indicated by 'the V usual-circuit symbolssufficient apparatus to enable a: clear-understanding of the invention.

rlhesubscribers station A is equipped with the usual talking instrumentalities comprising-the transmitter X, the induction coil I, the receiver R and the-'hoor switch 4, together with the signal bellsv 3v andthe telechronometer- T.` The mechanical construction of-'the telechronometer can bestbe V405--understood from a reading of the above mentioned-copending application to which ret erence is here-made'for those details. The electro-magnet of the telechronometer- T comprises windings, 5 and 6, the winding 5 451 beingincl'uded in one side oi the line to the central oflice and the winding (5 in the opposite side.V

This telephone line term-inates'at the cenf tra-l oilice in the.V line relay LRy and in the "ianswering'ljaclrs AJ and the calling jacks CJ,Ynot shown, as is the custom in a common battery telephone. system.

Responsive to the removalothe receiver R from the hook switch flA a circuitis completed from ground through the outer break springs on the relay COR, through the line conductor l and the winding 6 oi'- the telechronometer T, through the transmitter X, the primary winding or" the induction -coilfl,through the winding 5 of the telechronometer, through the malte contacts of hook switch 4, threughthe line conductor 2, through the inner break contacts of the cut-effi re-laiy, through the winding of the #line relay to battery.A Theline relay energizes over this circuit and closes the obvious circuit for the line lamp LL to indicate to the operator that the station A has initiated a call.

The operator picks up the answering plug Al) of the cord circuit CC and inserts it intothe answering jack AJ associated with the line A, thereby completing` a` circuit from Grounded battery through the sleeve relay SR through the sleeve of the plug and jack AP and AJ through the winding oi the cut-oft2 relay COR to ground.

The cut-oh" relay energizes over this circuit and opens the circuit ots the line relay LR to permit that relay to fall back and extinguish the line lampLL and teclear the line A ofl groundV andbatteryconnections. As is well understood by those versed in the telephone art, the centralL @Hice-battery has one of" its poles permanently connected to the ground.

`Whenthe connection has' been so established, the transmittei'oii the sub-station A will be supplied with battery over a circuit extendinc' from the negative Jeleot'batter C1 b l through the resistors Rl and R3 in parallel to the lower and upper terminals respectively ofthe relay AS, andl iroxn the positive terminal of battery wuich is also connected to ground, through resistance unitsl R2 and ltfll in parallel to the opposite terminals respectively of' the answering supervisoryl relayV AS.

Since thel resistanceunit Ril'is a-t its maximum resistance value wheny the resistance unit; R2 is at its minimum value, the connection through onset-'these resistors to one of the terminals of the relay AS will, in effect, be nulliied. Assume for the moment that the resistance Reis the high reels' ance unit, the transmitter current then traverses the circuit through resistance RQ'through the upper winding of the supervising relay AS to the tip connection of the plug AP and the AJ, over the line conductor l throughy the upper winding (l oi'tlie telechronometer T`,`-through the transmitter X, through the primary winding oli-the induction'coil I, through the lower winding 5 of the telechrenometer, through hook switch spring 4l and its maize contact, through the line conductor 2 tothe ring connection et the jack AJ' and the plug AP, through the lowerl vinding ofthe relay AS, through the resistance Rl, through the auinieter A, to thev negativeY gole ot' battery. t will be remembered that resistances Rl. and R2 are operated as. a pair so that when R2 is low in Value will be corr spondingly low in value.

The operatJr then throws the listening hey LK to connect her head set into the circuit, ovcrwhich she can converse with 'the subscriber at station A to ascertain what number he `is call-ing.

Cl? and jack CJ, through the line conductor' 2 of the line B, through the hook switch,

teleclirononieter winding, inductionV coil,

transmitter, and second telechronometer winding of the telephone substation B, kline conductor l leading therefrom, the tip conductor of the jack CJ and plug CP, the upper normally closed contacts of the ringing key lili, through the upper winding of the calling supervisory relay CS, through the aiiimeter A to negative battery. It will be noted that this connection does not include the resistance units lil-R4 inclusive, and therefore that the battery supply current to the transmitter of the sub-station B will not be reversed periodically.

rlhc cord circuit UO will contain other relays, lamps, keys, etc., as is customary with modern telephone cord circuits, but since these instruinentalities do not come within the scope of the present invention,

they have been omitted from the drawing to avoid an unnecessary complication thereof.

The parties A and B may now converse over the circuit just traced.

rllie plnngers 79 and 80 of the poleA changer associated with J@he cord circuit CC are operated by the cylinders Z3 and 7 4 in the manner pointed out in detail in the above mentioned copending application. The plunger 79 is withdrawn from the resistance units R1 and while the plunger 8O is pressed against the units R3 and R4 and vice versa.

This reversal of current at the cord cir-V4 cuit CC operates the telechronometer T through the windings 4 and 5 to register a Y charge against the calling subscriber A indicative of the length of time that the telephone has been in use on the dials of the tel-echroncincter. If the conversation continues, plungers 7 9 and 8O are re-operated in the reverse direction so that battery supply current is again reversed to the transmitter X through the resistances VRl and R2, and the telechronoinetei is again operated to assess another charge against the subscriber in the manner pointed out in detail in the copendiiig application referred to above.

If the subscriber attempts to secure his telephone service without having his telechronoineter T register the proper number of units therefor, he might endeavor to apply short-circuit to the winding 5 or to the winding 6 of his telechronometer. reptitious application of such a. shortfcircuit, ifit'be to one of the windings, will not however accomplish the purpose that the subscriber intended since each of the windly to be capable of operating the telechronometer 'properly without the assistance of the other Winding.

In the circuit previously traced for ther battery feed to the transmitter X at station`=-f A, resistancesy R1 and R2 were assumedto be of low value,rand therefore relay AS had negative potential impressed on its lower winding and positive potential on its upper winding. In this case plunger 79 is pressing "85 against R1 and R2 and plunger 80 is retracted 'from R3 and R4.

After a predetermined time has elapsed, the positions of plungers 79 and 8() arereversed by an operation of cylinders 73 and 74. Aslgo explained in my above mentioned copending application, this reversal takes place rapidly. After this reversal resistances R1y and R2 have high value and R3 and R4 low value, the lower winding of AS has positivel'95 potential impressed upon it, and the uppery winding has negative potential upon it, which it will be noted is the reverse of the initial potentials traced above.-

The wirechief could readilyascertain ifllo the winding was short-circuited by inserting a resistance meter in the circuit to the substation A, thereby measuring the loop resistance, it would be lowered by the short circuit ofthe winding. were'short-circuited there would be an appreciable reduction in the loop resistances and that fact wouldvbe readily ascertainable kby the corresponding 'increase in the transmitter supply currenthad over the line" circuit to the transmitter X.

4:[f the subscriber at'Station A attempts to disable the telechronometer Tby grounding one or the other ide of the line, the presencem of this ground is readily detected sincenormally the two sides of the line are balanced and free from ground. The application of ground to one orotlier side of the line would destroy the normal balance and could be readily picked up by the usual volt meteff:

test devices well known and understood by those skilled in the art. y'

Having thus complied to the statutes and shown `and described a preferred embodi ment of my invention, what Iconsider new" 25 and desire to have protected by Letters Patent is pointed out in the appended claims.

VlVhat is claimed is:

l. lncombination, a telephone station having a pair of line wires, adapted. to leadtl The sur# 70 ings is Vsuiificiently strong electro-magneticalg 75 If the two windings 5' 105 central, an*zele'cteofinagnetic devicef at :said

station; saidfeleetrmagnetic device inelud-v lingiza lpair =ozf= coils connected :serially leach-1n a limb( of the .telephone line and La perma- 'sfinent'magnet l: adapted rto :be :actuated :by sind coils.

Y .agsenose i ,line thereby; rendering shortseircuiting of the 'telechnenometer:readily. detectable.

'In -xwitnessiwhereof7 l hereunto subscribe .my naine this .25th .day-rotMarch, 1929.

GARRISONBABCQCIQ 2i In .combine-tien, a telephone station-hav- Jingaipair :of linenwires adapted to 4leadito im station, :said device including a"magnet,andv

a-pair of'lcoils. connected serial-ly each lin a :limb .fof the line and :acting -curnulativel-y to actuate the magnet in accordance Wiiththe polzxrity impressed upon the line..

1a `pair: Aof metal-lic conductors, anwelect'romagnetic device including Va ,pai-r .of 'actu- 4ating4 coils each connectedvserially in one conductor of ,said pair and .adapted for "12 energization together, andl a permanent lnagnetrad'apted to rbe `aetnatedby 'said coils. 4. In a telephone system,- fthe combination of Ha' :subscribers :station comprising the 'us-ual :tallcinfg instrumentalities connected -;to

mndrni-lnetefr ha-Vingtwo eectricallyy independent, and :equal frwindi-ngs, .one of which 1s l`ln1combination, ia telephone l,line :having:l

` "25 ,fa central '.oi'lice by a Ypair -of ,line conductors,

connectedl in :serial relation with each vof vsaid Yline condiicters.k

5: lin f a 'telephone rsysteln, the combination ofra snbsori'bers station comprisingthe iusual talking instrumentalitiesconnected to acenytrai; oticefby pair of .line 2 conductors, @and a meter havingftwo f-mechanicallyand elec- *(35 tricaflly. independent. windings 'of' identical electric -cliara-cteristics, oneof Ysaid -Wi-ndings :being connected in -ser1fi-l vrelation With cach-oil said conductors, :and a mechanism 'operated responsive :to :ein -energization ofr Gu ln ia telephone system, the combina-tion :a :subscribes: station :comprising the usual nnstrnnientalitiesfconnecte'd ato a centrall office `eyf afpai'r vof line conductors, .two f windings of identical .electric characteristics,- fonezfo-fz said kwindings :being connected 1n i 45'frnechaniealy and electrically independent;

'serial relation with each otssaid conductors7 iand a. mechanism operated .responsive to an 'l 50-ene rgization of said windings by electromagnetism set up; in saidl windings.

7.5 In na -telephone system, :the combination `o'ii'a' subscriber?s stationjcorrqrrising the usual instrumentallties connected ato a cen- 55:-,tral office ove-.rxan umgrfounded y two conc'luotorY circuit; a .meterxhaving two electrically.. balanced windings, one connected 1n each fof-

Images