US2048908A - Telephone signaling system - Google Patents

Description

y 1936. A. E. woomuFF 2,043,908

TELEPHONE S IGNALING SYSTEM Filed May 24, 1934 INVENTOR ALBERT E. WOODRUFF ATTY.

Patented July 28, 1936 TELEPHONE SIGNALING :SYSTEM Albert E. Woodrufl, Oak Park, 111., assign or to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application May 24, 1934, Serial No. 727,226

15 Claims.

This invention relates to telephone systems but more particularly to improvements in signaling arrangements in such systems. One of the primary objects of the invention is to provide an improved visual and audible signaling means at a subscribers telephone station. A iurther object is to simplify the signaling means and equipment at a telephone substation by eliminating the usual ringer coils and gongs and the condenser and instead utilizing the receiver-of the substation for an audible signal. A further object resides in providing a neon glow lamp at a telephone substation for controlling the signaling. An additional object consists in an arrangement employing a neon glow lamp which will permit signaling current to pass but will not permit voice currents to pass, thereby eliminating the transmission losses on a party line usually caused when ringers are employed at the substation. A further object is to provide an arrangement for removing the neon glow lamp from the circuit when the receiver is removed and the telephone placed in talking condition. Other objects and features of the'invention will appear more fully from the detailed description thereof hereinafter given.

' In the arrangements of the invention the neon glow lamp is connected directly across the line conductors in series with the'receiver at the substation and is shunted out by the substation transmitter when the receiver is removed. The application of signalingcurrent of audible frequency to the line breaks down the lamp and-at the same time actuates the receiverto transmit an audible signal or tone. In =order-to break down the neon lamp a direct current-battery of suiilcient voltage is superimposed on the audible frequency current, the direct current being used both as a means of ionizing-the neon tube and for polarizing the receiver in case it is of the direct current type without a permanent magnet. After the lampglows it presents a comparatively low resistance path to the receiver because, due to the characteristics of these lamps, they will stay operated on a lower voltage than that required to break them down.

The invention will be more fully understood from the following description together with the drawing which discloses a preferred embodiment of the invention.

Referring to the drawing, there is indicated diagrammatically for the purposes of illustration a manual switchboard having cord circuits such as C. These cord circuits are connected to an operators telephone by means of answering key AK, while a ringing key RK is for signaling purposes. Each subscribers line terminates at the switchboard in a line jack J, and has associated with it the line lamp'L. A single substation on a line is shown at B while a .multi-par'ty line 5 and 6 has a number of substations, A, A and A connected to it. The substation A as well as the within the audible range, together with a fairly 15 high direct current potential superimposed on the alternating cur-rent, is controlled .by the signaling keyi RK in the cord circuit C.

In order to better explain the invention the operations which take place when a call is made y will now be pointed out. The subscriber at substation B desiring to establish a connection with a subscriber on the party line 5 and 6, substation A for example, will remove his receiver thereby establishing a direct current circuit path through the-transmitter and r-eceiverat substation B, line circuit, contacts of jack J, and through the line lamp L. The .line lamp L' lights and the operator answers by .inserting the answering plug P" into jack J thereby extinguishing the lamp L at the ,jack J contacts. The answering key AK is then operated connecting the operators telephone directly with the line conductors of substation B. The relay 9 being connected in this circuit operates and closes the circuitfor supervisory lamp AL. It also. furnishes talking current for the telephones from the battery BI' through its windings. The operator upon ascertaining the wishes of the subscriber at substation B inserts calling plug P of cord G into jack J thereby separating the jack contacts I and 8 and connecting the cord C directly to the line conductors '5 and 6. The operator now signals the substation A by operating the signaling key RK which thereby connects a source of fairlylow voltage alternating current of any desired audible frequency, for example from 300 to 1000cycles, through the primary and secondary windings of transformer TR, comparatively high voltage direct current. battery 3-? superimposed upon the alternating current, contacts of key 'RK, plug P and jack J, line conductors 5 and 6, and'through the neon glow lamp N and the receiver R at substation A. The circuit likewise extends in parallel throughall the other substations A and A. The direct current flowing in the above circuit path ionizes the neon glow lamp N, breaking it down and reducing its resistance so that it remains lighted and provides a low resistance path to the receiver R for the alternating current flowing in this circuit. The direct current in this circuit likewise polarizes the receiver R in case it is of the direct current type not provided with a permanent-magnet. The illumination of the neon lamp'N will attract the attention of the person at the substation A in case he is some distance from his telephone or in case his hearing is slightly defective. The receiver likewise respondsto the frequency of the alternating current to send out an audible howl or tone to attract the subscribers attention. It will be understood that the neon glow lamp as well as the receiver at the other substations A and A on the same'line, will respond to the signaling current, and the operator at the switchboard therefore in order to call the substation A only, will manipulate the signaling key RK in accordance with a particular codeof long and short periods of signaling.

In answering the call the receiver R'is'removed from the switchhook S, thereby connecting the transmitter T in series with the receiver Rand the line conductors 5 and 6, while at the same time the transmitter T which is of lower resistance shunts the neon glow lamp N from the line circuit thereby extinguishing it and allowing the receiver R. to function normally. The operator restores the signaling key RK and then her answering keyAK and retires from the connection. Thetelephone substation B is now in direct communication with substation A and conversation can proceed, current for talking pur-'- poses being furnished for both telephones through the windings of relay 9. The supervisory lamp AL therefore remains lighted until both parties have hung up, whereupon the lamp goes out and theoperator withdraws theplugs B and P from jacks J and J to restore the circuits to normal condition.

It will be observed that when the telephones A and B are in direct communication the receivers.

at substations'A' and A will not interfere with the transmission or present a loss in transmission usually occurring with. the ordinary types of ring? ing apparatus employed. This is so because the neon glow lamps present an open circuit condi-,.

tion to voice currents on the line and willpermit only high potential signaling current to flow th1'ough,them..

The source of high .potential direct'current comprising battery B-? which is'superimposed on the alternating current may satisfactorily be" substituted for a single direct current battery of suflicient voltage to break down the neon lamp and at the same time maintain it lighted after having operated. In order, however, .to actuate the. receiver R this direct current source would have, to be rapidly interrupted as by a buzzer. Similarly thesource of direct current.B2 could be dispensed with and only an alternating cur-' rent sourceused to break down the neon lamp and maintain it provided it were. of high enough potential, but not to injure the receiver R. It will readily be apparent likewise that neon glow lamps I are constructed to breakdown on different voltages, and therefore on'the party line illustrated each substation can be provided with a different neon glow lamp while at the switchboard the operator would be provided with'diflerent signaling keyseach connected to a different potential of battery. In this manner'the operator would be limited to the exact disclosure but only to the extent of the appended claims.

- What iselaim'ed'is:

l. A signalingcircuit for a substation telephone comprising aneonf lamp connected directly in series withQthe telephone receiver when the receiver is on the switchhook.

2. Asubstation telephone line, a signaling circuit bridged; across said line at said substation when the receiver is on the switchhook, said signaling circuit including a neon lamp and a receiver connected 'directly in series therein.

3. A telephone line terminating at a substation, telephone instrumentalitiesincluding a receiver at saids'ubstation'and a switchhook, a signaling circuit'normally connected across said line at said substation, before the receivenis removed from the switchhook; including said receiver, and a neon lamp'in series-with said receiver acting as a normally open'valve therefor. 3

4. Ina substation telephone set, a normally closed signaling circuit including a neon lamp and the telephone" receiver directly'connected in series, and means for shunting said neon lamp from said circuit when the receiver is lifted from the switchhook. Z

5. In a-substation' telephone set, a switchhook,

asignaling circuit at said set including a neon lamp and the telephone receiver normally con-' ncted in series when the receiver is on the switchhook,- and-means for connecting the transmitter of said set inshuntof said neon lamp to render it inoperative in said signaling circuit and for connecting the transmitter in series with thereceiver for talking purposes; a a

6. In a substatio'rrtelephone set, a signaling cir cuit, a"neongl'ow lamp and-telephone receiver connected insaid ignaling" circuit, means for transmittingasource of batterypotential to said signalingci'r cuit to break 'down said neon lamp, and means fortransniitting 'a different source of current to said circuit to actuate said telephone receiver as a signal.

- '7. In a. substation telephone set, a signaling cir- I cuit, a neonglewiam and telephone-receiver connected to said signaling circuit, means for connectin ga source'o'f direct current potential to said signaling circuit to "operate said neon lamp as a visible signal, and means for connecting a source of alternating current potential to said signaling circuit to operate said telephone receiver as an audible signal. 4

8. In a substation telephone set, a signaling circuit includinga neon glow lamp and a telephone receiver, a source of direct current and a source of alternating current, means for connecting the source of 7 direct current potential superimposed upon the source of alternating current to said signalingcircuit to operate said neonlamp as a visible signal andSaid receiver as an audible signal. r

9. In a substation telephone set, a signaling circuit. including a neon glow lamp and'a telephone receiver, a source of :direct current and a source ci alternating current, means for connecting said source of direct current potential superimposed upon said source of alternating current to said signaling circuit to operate said neon lamp as a visible signal and said receiver as an audible signal, and a shunting circuit including a telephone transmitter for removing said neon glow lamp from said signaling circuit.

10. In a party line telephone circuit, a line having a plurality of telephones thereon, a signaling circuit for each telephone on the line, a neon glow lamp and a receiver in each circuit, means for operating all the neon lamps and receivers to signal said telephones, means for removing the neon lamp from the signaling circuit of the desired telephone, but maintaining the receiver for talking purposes, the neon lamp of the remaining telephones presenting an open circuit to voice currents and preventing transmission losses.

11. In a multi-party telephone line, a line having a plurality of telephones thereon, a signaling circuit for each telephone on the line, a neon glow lamp and the telephone receiver in each circuit, means for transmitting signaling current to said line to operate said lamps and receivers at said telephones as visible and audible signals respectively, means for removing said neon lamp at the desired telephone from said signaling circuit by shunting it with the telephone transmitter, said receiver being maintained in said circuit for talking purposes, the neon lamps of all other telephones preventing the passage of voice currents and the consequent loss in transmission from the called telephone.

12, In a telephone circuit, a telephone receiver arranged to be operated both as a telephone instrument and as a signal, and a neon glow lamp connected in series with said receiver in the signaling circuit to prevent the operation of the instrument by talking current and to permit the operation thereof by signaling current.

13. In a telephone circuit, a telephone receiver operated either as a signal or for telephone purposes, and a neon glow lamp connected to said receiver and operated therewith as a signal but rendered inoperative when said receiver is used for telephone purposes.

14. In a telephone circuit, means for transmitting signaling current and talking current over said circuit, a telephone receiver in said circuit responsive to said signaling current to operate as a call signal and responsive to said talking current to operate for talking purposes, and a neon glow lamp connected to said telephone receiver for permitting said signaling current but not said talking current to operate said receiver.

15. In a telephone circuit, means for transmitting signaling current and talking current over said circuit, a telephone receiver in said circuit responsive to said signaling current to operate as a call signal and responsive to said talking current to operate for talking purposes, a neon glow lamp connected to said telephone receiver for permitting said signaling current but not said talking current to operate said receiver, and means for rendering said neon glow lamp inoperative and to change said circuit to permit the passage of said talking current.

ALBERT E. WOODRUFF.

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