US1498862A - Telephone-transmission system - Google Patents

Description

June 24'?, 1924. f 'gZ w. H. BENDERNAGEL .TELEPHONE TRANSMISSION SYSTEM Patented June 24, 1924.

UNTQ STATES PATENT OFFICE.

'WILLIAM H. BENDERNAGEL, OF QUEENS, NEW YORK, ASSGNOR .TO-WESTERN ELEC.-

TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A COBPORATI/ONy OF NEW" l YORK.

TELEPHONE-TRANSMISSTON SYSTEM.

Application led December 16, 1919, Serial No; 345,250.

T 0 all wlw/m 25, may concern.'

Be it known that I, WILLIAM H. RENDER- NAGEL, a citizen of the United States, re-' siding at Queens, in the county of Queens,

v State of New York, have invented certain new and useful Improvements in Telephone- Transmission Systems, yof which the following is a full, clear, concise, and exact description. y

This invention relates to telephone transmission systems, and more particularly to such systems in which repeaters are employed. The object of the invention is to economize in equipment byV providing mea-ns whereby several'conversatlons may be amwhich shall be common tol a plurality of op-l Another fea' eratorscord or link circuits. ture is to provide for using a single repeater equipment for a plurality of cord or link circuits so that the repeater may be associatedwith said circuits in lsuch a'manner that conversations may be carried'on simultaneously over all'pairs of'linesv joined by the cord circuits. Another .feature is to render the repeater operativeonly when at least a single cord circuit is connected to two subscribers lines. Another feature is to provide signals and to provide a distributor which is rendered operative at the proper times. Other features and advantages of the invention willbe obvious as the description proceeds.

The invention will be understood from the description in connection with the drawing which shows a repeater equipment consisting of two one-way amplifiers connected to a distributor which in turn is connected to a cord circuit.

In the drawing reference characters A and B designate subscribers7 line circuits which are provided with the usual equipment such as line signal, signal relay, telephone set, jack, etc. When the subscriber Y at A removeshis telephone from the hook,

the relay 2 is energized, thereby closing a circuit through the line lamp L.

Upon noticing the line signal at L, the operator inserts her plug P intojack J. This energizes the cut-off relay l, thereby extinguishing, light L and at, the same time lights the light L and energizesj the relay 3 byv a circuit which can be traced froml ground throughrelay 1 sleeve contacts of jack? J and plug P, lamp L, relay 3 and battery to ground. The insertion of plug Pin jack J simultaneously closes a circuit from battery, upper half of left-hand wind` ing ofl transformer T,"tip contacts of plug' and jaclgsubscribers set, ring contacts of jack and plug, relay il, lower half of lefthandV winding vof'transformer T, back to battery. This energizes relay 4,' thus clos-' ing its contact and'extinguishing light L', but maintaining relay 3 eneregized.'v

The relay 3u`pon energization closes its leftehand and right-hand contacts thereby starting the motor M through the circuit which may be traced from ground, left-hand contact of' relay 3, motor IM, battery to ground. The closing of the right-hand contact of relay closes a circuit there through.' and through the leftdiand winding ofmarginal'relay`3- and battery to'ground.' The motor M drives the' brushes of the distributor in a manner whichwillno-wbe eX- plained.

The distributor shown in theV lower part of the figure consists of a number of sectors S1, S2, S3, etc., insulated from each other and each sector containing. a number ofsegmen'ts, s1, s3, S5, which are also insu` lated from each' other. tors into which the distributor is divided is equal to twice the number of cord circuits for which it is designed to be usedas more fully explained below. Thus, sectors S1, and S, belong tof one cord circuit, sectors S2 and Sl'f, to a secondcord circuit, etc. On the face ofthe distributor are disposed eight concentric rings 011,93, r3, etc. For'connecting the repeater inthe various cord circuits in accordance with the various positions of the arms a, two rigidly* connected arms a and a are mounted at the center of the distributor and are driven at a very high speed, say 4,000 revolutions per minute, for eX- ample, by the motor M, whose shaft m is connected to the axis of the arms ce, a', by connections not shownv on the drawing. The arms a, a, are provided with a number of brushes b1, b2, b3, etc., which are insulated from each other, and serve to momentarilyV connect thevarious segments s1, s2, s3, tothe rings r1, r2, r3, etc., while the arms are re- The number. of secy lio ,infissi-.Wm

volving, as will be obvious from the draw ing. The terminals of the repeater equipn ment are connected to the eight rings of the distributor as shown. The right and lefthand windings of the transformers T and T' respectively and the terminals of the balancer nets N and N' of a single cord circuit are connected to the segments 81, s2, s3, etc., of an opposing pair of sectors S, while similar terminals of each cord circuit are connected to the other pairs of opposing sectors of the distributor.

When the operator inserts the plug P' into the jack J', the cut-ofirelay 1' is energized as is also the right-hand winding of relay 3' through a circuit from ground, relay 1', sleeve contacts of jack and plug, lamp L', right-hand winding of relay 3', battery to ground. The current now passing through the two windings 0f relay 3' energizes it sufficiently to close its contact, thus completing the circuit from ground, through battery, oontact of relay 3', wire 21, and the filaments of repeaters R and R' to ground, thus rendering the repeaters operative.

When the subscriber B removes his receiver from the hook, a circuit is completed from battery through the upper right-hand winding of transformer T', tip contacts of plug P', andA jack J', subscribers set, ring contacts of jack and plug, relay 4', lower half of right-hand winding of transformer T', back to battery. This energizes relay 4 and short-circuits lamp L'l, thereby extinguishing the same. It is thus seen that the insertion of plug P into jack J starts the distributor arm to revolving and that the insertion of both plugs of a cord circuit into jacks renders the repeater bulbs operative and that either subscriber A or B may signal the operator through lamps Ll or L'1 by moving their hooks up and down, since such an operation deenergizes and energizes the relays 4 and t' respectively, thus short-circuiting Vthe lamps Ll and L'1 respectively, and removing the short circuits therefrom.

`With the plugs in the jacks, either subscriber can be rung by operating the ringing keys A and K' in the usual way. lNit-h the receivers off the hooks, voice transmission will be amplified by passing through the amplifier equipment as follows: Voice currents from subscriber A through his equipment, the. tip and ring contacts of j ack J and plug P, relay 4E and left-hand winding of transformer T, where it is transferred t0 the right-hand winding of transformer T and passes through wire 5 to segment s1 (while arms a, a' are in proper position) through brush l, ring r1, wire 6, condensers and primary of transformer t, wire 7, ring r, brush .7)7, wire v8, balancer N, wire 9, segcirculateV ment S5, brush b5, wire 10, condensers and primary winding of transformer t, wire 11, ring r3, brush 3, segment s3, Wire 12 to the right-hand winding of transformer T. At transformer t, the voice current is transformed to the secondary of transformer t where it circulates through the input circuit of repeater R and is amplified and passes to the output circuit of repeater R to the transformer t1, from whence it divides, one f half passing through wire 13, ring rg, brush 228, wire 14, balancer N', wire 15, segment s6, brush 5G, ring r6, wire 16, condensers, transformer t1, to ground, and the other half passing through wire 20, ring r2 brush Z22, segment s2, lead 19, left-hand winding of transformer T, lead 18, segment s4, brush b4, ring r, lead 17, condensers and primary winding of transformer t, to ground. At transformer T' the current is transformed to the right-hand winding and passes through the tip and ring contacts of plug P' and jack J' to the telephone set of subscriber B. Voice currents from subscriber B will be amplified in exactly the i same manner except that they will pass through the bulb B', instead of the bulb R.

Only one cord circuit with its connections is shown in the drawing. Tt will be obvious that duplicate cord circuits will have the contacts of their relays corresponding to relay 3 connected in parallel to the motor M and the contacts of their relays corresponding to marginal relay 3' will likewise be connected in parallel to the wirel 21 for energizing repeater filaments whenever the two plugs of any cord circuit connect any two subscribers line circuits.

The connections R1, R1', R11 and R11' operate as a filter in the well known way as illustrated for example in the patent to Gr. A. Campbell No. 1,227,114, May 22, 1917, to prevent disturbances caused by the make and break contacts of the distributor brushes from reaching the amplifiers, but at the same time permitting the high frequency voice currents to be amplified. The network N balances the line circuit of subscriber A and the filter R1' balances the filter B1 with respect to the repeater. Similarly the network N1 balances the line. circuit of subscriber B and the filter R1, balances the filter R11'. The connection is maintained between the repeater equipment and any individual cord circuit only a fraction of the time. For example, with an eightcord circuit distributor, each cord circuit will be connected to the amplifier one-eighth of the time. The arm a, a' will be driven by the motor M sufiiciently rapid so that about fifty or more contacts will be made per second in order that in effect, continuous transmission for each set of subscribers will be IGH maintained, and will be amplified a proportionate amount by the amplifier 1i, R. In this way, a single repeater equipment is available for a plurality of cord circuits and may be used simultaneously with j all of them without cross-talk, thus saving a duplication of amplifying equipment.

Any given link circuit is alternately in the closed condition and the open condition, each open period being about fifteen 'times as long as each closed period, since the distributer after closing one link circuit must open that circuit and closeseven other circuits in succession before again closing the one circuit. Transient currents occur of course at the make and at the break. Thus, during each period when the distributer brushes are not touching the contacts in a given cord circuit the current in that circuit varies from the current which would flow were the circuit not subject to interruptions. This variation, appearing once at every revolution of the distributer or at a frequency of 6632,- cycles per second where the distributer makes 4000 revolutions per minute, tends to produce a low frequency wave of current in the circuit. Such a wave tends to produce a low tone in the receiver. Therefore, the filters R, B-l, R11, R11 are inserted in the circuit for the purpose of preventing as far as is feasible the appearance of such a current wave. Of course, the design of these filters must be such that they will not unduly interfere with t-he passage of the waves of current corresponding to the voice waves of sound. rThe filters may be designed in accordance with the princi-ples set forth in the Campbell patent referred to above, and may be of any suitable type, the specific form of the filter being no part ,of the present invention.

What is claimed is:

l. In a telephone system, a plurality of subscribers line circuits terminating at a central switchboard, a plurality of link circuits, a repeater, means whereby said repeater may be connected in said link circuits in rapid succession, and means for rendering said repeater operative when any one of said link circuits is connected to any two of said subscribers lines.

2. In a telephone system, a plurality of subscribers line circuits terminating at a central switchboard, a plurality of link circuits, a repeater, a. distributor for connecting said repeater in said link circuits in rapid succession and means for rendering said repeater operative when any one of said link circuits is connected to any two of said subscribers lines.

3. Tn a telephone system, a plurality of subscribers line circuits terminating at a central switchboard, a plurality of link circuits, a repeater, a distributor having a revoluble arm, for connecting said'repeater. in said link circuits in rapid succession, means for revolving said arm when a'call initiated by any one of said subscribersis answered by an operator, and means forv rendering said repeater operative fwhenany one of said link circuits is connected toran f two of saidsubscribers lines. f f 4. InV a telephone system, ai plurality lvof subscribers line circuits terminating at a central switchboard,'a plurality of. link circuits, a repeater, and a distributor for con'- necting said repeater in said link circuits at sufficient frequency to produce a low tone, and means for filtering out the distributor make and break disturbances before they reach said repeater. v

5. In a telep-hone system, a plurality of subscribers line circuits terminating .at a

-central switchboard, a plurality of link circuits, a repeater, and a distributor for connecting said repeater in said link circuits at a low frequency within the range of hearing, and means for filtering out the distributor make and break disturbances before they reach said repeater, without interfering with voice transmission.

6. In a telephone system, a plurality of subscribers line circuits terminating at a central switchboard, a plurality of link circuits, a repeater equipment consisting of two one-way amplifiers, and means for connecting said repeater into and disconnecting it from each of said link circuits at such a frequency that the interruptions do not seriously affect the intelligibility of conversation being transmitted through said link circuits, and maintaining said repeater connected in each link circ-uit for substantially equal intervals of time.

In a telephone system, a plurality of subscribers line circuits terminating at a central switchboard, a plurality of link cir cuits, a repeater equipment consisting of two one-way amplifiers, means for connecting said repeater into and disconnecting it from each of said link circuits at suchV a frequency that the interruptions do not appreciably affect the intelligibility of conversation being transmitted through said link circuits, and maintaining said repeaterconnected in each link circuit for substantially equal intervals of time,pand means to prevent the disturbances caused by said make and break connections from reaching said repeater.

8. A telephone system comprising a plurality of transmission lines, an amplifier common to said lines, balancing networks corresponding to said lines, and means for connecting said amplifier in operative relation to said lines and corresponding networks in rapid succession.

9. A telephone system comprising a plurality of transmission lines, an amplifier common to said lines, balancing networks corresponding to said lines, and means Jfor momentarily connecting said amplifier in operative relation to each of said lines and the corresponding networks at suciently close intervals to provide for intelligible speech transmission over said transmission lines.

10. A telephone system comprising a pilurality of transmission lines, an amplifier common to said lines, means for connecting said amplifier in rapid succession with said transmission lines, and means rendered operative' when any of said transmission lines are taken for use for rendering said connecting` means active.

1l. A telephone system comprisingl a plurality of transmission lines, an amplifier common to said lines, means for connecting incassa said amplifier With said transmission lines, and means rendered operative when any of said lines are in use for rendering said connecting means active and for rendering said amplifier active.-

l2. A. plurality of. lines, a repeater comprising a unidirectional current transmitting amplifying element having an input circuit and an output circuit, and means comprising a rotary commutator for effectively connecting said out-put circuit to dit- 'erent ones of said lines in rapid succession and for also effectively connecting Said input circuit to different ones of said lines in rapid succession.

In Witness whereof, I hereunto subscribe my name this 12th day of December, A. D.

XILLIAM H. BENDERNAGEL.

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