US2073586A - Telephone system - Google Patents

Description

March 9, 1937. A, J;PAR,Ss| 2,673,586

TELEPHONE SYSTEM Filed Nov. 27, 1935 Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE Anthony J. Parlssi, Gohoes, N. Y.

Application November 27, 1935, Serial No. 51,733

22 Claims.-

My invention relates to the signaling or annunciator phase of communicating systems and thefundamental circuits embodied therein are generally similar to those disclosed in my copending application Ser. No. 701,747 which was -filed in the Patent Ofiice on or about the 11th day of December, 1933.

My invention more particularly relates to the association with a telephone circuit of an electric circuit having a separate source of energy and including a visual signaling device which, through the means associating the two circuits,

is operated in a predetermined manner when a signaling current energizes the telephone circuit.

5 In view of the fact that the visual signaling circuit is dependent upon a. source of energy separate from that feeding the telephone circuit and in order to insure continuity of service, that is, the emission oi. a signal of one character or another when the telephone signaling circuit is energized, my invention has for a first object the provision of means for efiecting an operation of the annunciator in the telephone circuit in the event of a failure of the visual signal or the failure of '25 power in its circuit.

Obviously, a visual signaling device is provided in order that a noiseless signal may be emitted at, for example, a subscribers station in a telephone system where quietness is desirable. In some instances, circumstances may require intermittent absences of a person from view of the visual signal and, in such a case, it is desirable that an audible signal be given in the event that the visual signal is not answered within a predetermined interval of time. My invention, therefore, has for another object the provision of means for effecting in response to an energization of the telephone circuit, first, the emission of a visual signal and secondly, after a predetermined time interval of operation thereof, the emission of an audible signal.

Inasmuch as I preferably use an incandescent lamp as the visual signaling device in circuit in a commercial lighting system, my invention contemplates, for a further object, the provision, in combination with a lamp andswitch of a current intermitting device and circuit controlling means operable in response to an energization of a telephone signaling circuit whereby, normally, the lamp may be switched on or oil? for ordinary illuminating purposes, but upon an energization of the telephone circuit, the normal operation of the lamp is interrupted and a flashing operation thereof occurs.

5 My invention has for further objects the provision of means for maintaining the signaling operation of the lamp after an initial flow of signaling current in the telephone circuit, means for determining the maintained lamp operation after a predetermined time interval of operation thereof and means for discontinuing the signal emission when the talking circuit is completed at the subscribers station. I

A still further object resides in the provision of a manual control whereby either the visual or the audible signaling device may be selected and operatively connected for use, or both signaling devices may be connected to operate simultaneously. 1

With these and other objects in view, my invention includes the novel elements and the combinations and arrangements thereof described below and illustrated in the accompanying drawing in which- Fig. 1 is a wiring diagram of my invention in its preferred form; and

Fig. 2 is a perspective view of a motor operated switch representative of one of the elements incorporated in my device.

Referring to Fig. 1, I indicates an incandescent lamp connected between the legs 2 and 3 of an electric lighting circuit, a switch 4 being interposed in the leg 3. The plug 5 and socket 6 constitute an optional element which lends flexibility to my device and are illustrated merely to show a manner in which various lamps or a circuit comprising a plurality of lamps may be connected to the circuit comprising the-control devices of my invention. Hence, inasmuch as the lamp I may be connected directly in circuit and the legs 2 and 3 and the third leg or conductor 1, which is connected at one end to leg 3 intermediate the switch 4 and lamp I, are electrically connected through the plug and socket to three connecting, electrical conductors, I have designated the latter by the same reference characters as the conductors to which they are connected.

Leg 2 constitutes the common return conductor of the lamp circuit and is connected to one main line 8 of the electric lighting service mains 8 and 9. Leg 3 is connected to a contact ill of a relay ll, one armature l2 of which in its normal position, that is, when the coil of the relay is unenergized, engages said contact and closes a circuit from leg 3 to conductor l3 to which said armature is connected. Conductor I3 is in turn connected to the main line 9 of the service. This circuit through legs 2 and 3 to lamp I may be termed the normal lighting circuit.

For simplicity of illustration, I have shown the relay I I as composed of four armatures. Obviously, a single armature having insulated segments adapted to engage the respective contacts and to perform the same function as those illustrated may be employed.

A second armature H which is also connected to conductor I3 is, upon an energization of relay adapted to engage contact l5 to which one terminal l8 of a current intermitting device, indicated generally at H is connected through conductor l8. The other terminal IQ of the device I1 is in turn connected to conductor 1.

The current intermitting device may constitute what is commercially termed a flasher button. Obviously, any suitable means may-be employed which will produce a desired operation of the incandescent lamp which differs from its normal one. The device H, which is illustrated diagrammatically for descriptive purposes, comprises a fixed contact 2|) and'a movable contact 2|. Contact 20 is electrically connected with terminal l9 and contact 2| is in electrical contact with and supported on a bimetallic element 22 which is secured at one end to the terminal l6. A wire 23 of suitable ohmic resistance is coiled about the bimetallic element and electrically connected between the terminals l8 and I9. Wire 23 is, therefore, connected directly in series with conductors 1 and I8. When the relay closes the lamp circuit through its armature l4, current flows through wire 23, it being in series with the filament of lamp Wire 23 is designed to generate and radiate suflicient heat to cause the bimetallic element 22 to warp toward terminal l9, whereupon contacts 20 and 2| will touch, causing the resistance element 23 to be shunted by the bimetallic element itself. The current flow through the wire 23 is not sufficient to illuminate lamp l but, upon the engagement of contacts 29 and 2|, the lamp is connected directly across the mains 8 and 9 and beomes fully illuminated. This direct circuit to the lamp is maintained until contacts 20 and 2| are disengaged due to the cooling and retraction of the bimetallic element towards its normal position. Obviously, during the maintenance of this circuit, the above described cycle of operations of the device |1 continues causing an intermittent illumination of the lamp From the foregoing, it is apparent that an energization f the relay among other funcductor 28 to leg 2 of the lamp circuit andthrough conductor 29 to one contact 30 of a relay 3|. The armature 32 of the relay 3| is adapted to engage contact 39 and a secondcontact 33 electrically to connect said contacts, contact '33 being connected through conductor 34 to conductor l3.

It will be noted that the elements of my invention; described in the foregoing, with the exception of relay 3| are connected or are connectible in circuit with the mains 8 and 9. These mains have hereinbefore been designated as electric lighting service mains. Obviously, any suitable source of power may be employed to which the mains 8 and 9 are connected but, inasmuch as my invention, in its preferred form, contemplates the normal use of lamp for ordinary illuminating provided and the circuit arranged accordingly, I-

have designated conductors 8 and 9 as service mains with the understanding that they are connected to a commercial lighting distribution system.

The relay 3|, however, is connected in circuit at the subscribers station of a telephone system and is adapted to be operated in response to an energization or flow of signaling current in said telephone circuit. The subscribers station of the telephone circuit is diagrammatically illustrated as comprising the terminals 35, 35, 31 and 38 which comprise the points of connection between the usual telephone circuit and trunk lines and the circuit embodying my invention. The telephone trunk lines, indicated at 39 and 40, are connected to terminals 39' and 31, respectively, 36. The terminals 4| and 42 are provided for connection with the subscriber's telephone set and a detailed description thereof will not be entered into at this point. One terminal of the usual bell or audible signaling device 43 is connected through a condenser 44 to terminal 39' and the trunk line 39 and the other terminal thereof is connected to terminal 38. A conductor 45 connects terminal 38 to two contacts 45 and 41 of a manually operable switch, indicated generally at 48.

Switch 48 is interposed in the bell circuit so that the subscriber may select and connect either the bell or the relay 3| in the telephone signaling circuit. In other words, the subscriber may se lect either the visual or lamp flashing signal, or, the audible or bell signal. At the same time, the switch 48 is preferably constructed, as illustrated, also to connect both types. of signaling devices in circuit for simultaneous operation.

The switch blade 49 of switch 48 is connected through conductor 59 to the trunk line 48. Hence, when blade 49 engages contact 45 or 41 the bell 43 is connected directly across the trunk lines 39 and 40. On the other hand, when blade 49 engages a third contact of switch 48, the bell is disconnected and a new circuit created. One side of this new circuit includes conductor 52 which connects said contact 5| with a movable contact arm 53 of a two-position, motoroperated, switch indicated generally at 54, which will be hereinafter described, and conductor 55 which connects relay 3| through condenser 58 to one contact 51 of the motor-operated switch 54. The other side of this circuit comprises conductor 58 which connects the relay 3| to the telephone line 39.

Assuming for the moment that the circuit is completed through contact arm 53 and contact 51 of the motor-operated switch 54 as shown, it will be seen that switch 48 serves to connect either the bell 43 or the relay 3| across the telephone trunk lines 39 ,and 48. Switch 48. however, is also preferably designed to connect both the bell and the relay 3| across the trunk lines 39 and 49 so that a simultaneous operation of both will occur. For this purpose, the contact 41 and a fourth contact 59 are provided, contact 41 being connected, as above described, to conductor 45 and contact 59 being connected to conductor 52. It will be evident, therefore, that when contact arm 49 is turned to engage. contacts 41 and 59, the bell 43 and relay 3| will both be connected across the telephone trunk lines.

, Inasmuch as my invention contemplates the provision of means for effecting the emission of terminal 39' being connected to terminal a visual signal, let us assume that arm 49 of switch 48 is in engagement with contact 5| and the telephone trunk lines 39 and 40 are energized. Signaling current flows from line 40 and terminal 31 through conductor 50, arm 49 and contact 5| of switch 48 and through conductor 52.to arm 53 ofmotor-operated switch 54. Further assuming that arm 53 lies in the position'illustrated in engagement with contact 51, current flows therethrough and through conductor 55 and con- Y denser 56 to relay 3| and thence through conductor 58 to terminal 36 of the other trunk line 39. Hence, relay 3| is energized and the armamm 32 thereof is picked up forming an electrical connection between the contacts 30 and 33 thereby connecting the primary 21 of transformer 26 across the electric service mains 8 and 9. The transformer primary circuit may be traced as follows. One terminal of the primary winding is connected through conductor 28 to conductor 2 which is in turn connected to line 8 of the mains and the other terminal of the primary winding is connected through conductor 29v to contact 30, of relay 3|, through the armature thereof to contact 33, and thence through conductor 34 to conductor l3 which is connected to line 9 of the service mains. nected across the service mains, current flows through its secondary circuit which includes the relay and conductors 2'4 and 24 and the armatures |2 and M of said relay are attracted by the pole piece to a position opposite to that illustrated. Hence, the connection of the primary of transformer 26 across the mains 8 and 9 effects, through an operation of relay I, a discontinuance or interruption of the normal lighting circuit through leg 3 and substitutes therefor the third leg which includes conductor 1, current intermitting device I! and conductor l8.

From the foregoing, it is apparent that, assuming the switch 48 and motor-operated switch 54 are in the positions illustrated, an energization or flow of signaling current in the telephone trunk lines 39 and 40 will effect an interruption of the normal lighting circuit and the creation of a second circuit including the device I1 and the incandescent lamp The conductor 1, device l1 and conductor l8 form, in effect, a shunt circuit around the switch 4 which is disposed in the device I1 is connected in series with the lamp and across the service mains.

The above described operation of my invention illustrates the results obtainable with the fundatherefor, an intermittent illumination thereof occurs as a flashing, visual signal when the telephone circuit is energized. However, it is desirable that the visual signal be emitted for a period of time exceeding the duration of the telephone signal and that such period of time be limited to a predetermined interval in the event the When the transformer 26 is consignal is not answered. Furthermore, it is desirable to automatically cut off the visual signal when the telephone talking circuit is opened and means, as hereinafter described, are provided to attain these objects.

A very important feature, however, of my invention resides in the means which I have employed to insure continuity of service or, in other words the emission of one signal in the event of a failure of the other. Due to the fact that the visual signaling device or incandescent lamp is dependent upon a source of electrical supply separate. from that supplying the telephone lines, I have provided a means, hereinbefore referred to as a motor-operated switch 54, which is adapted to connect the bell in the telephone circuit in the event of a power failure in the lighting circuit or the 'inoperativeness of the incandescent lamp. As hereinbefore described, the movablc contact arm 53 of switch 54 when in engagement with contact 51 connects the relay 3| in the telephone circuit assuming, of course, the arm of switch 48 is in the position illustrated. The arm 53, as diagrammatically illustrated, is operated by a motor 60 which is connected to and receives energy from the lighting service mains. Assuming upon energization of the motor its shaft rotates clockwise, a projection 6| on the rotor shaft'urges the arm 53 in engagement with contact 51. It is to be understood that the rotor of motor 60 is designed to return to a predetermined positionwhen unenergized and in such position permits arm 53 to engage a contact 62. In other words, the rotor has a fixed, unenergized position and is designed, upon energization, toproduce a predetermined torque sufficient merelyto urge arm 53 against contact 51. The contact 62 is connected by conductor 63 to conductor 45. Hence, when motor 60 is unenergized, the circuit to relay 3| is opened and the bell is connected across the telephone lines 39 and 40.

The motor-operated switch 54 is illustrated in greater detail in Fig. 2 and the arm 53 and projection 6| are therein shown-as combined in the form of a contact arm 53' which is secured to and movable by the motor shaft 60I. Arm.53' is shown in a position intermediate and spaced from contacts 51 and 62 for clearness of illustration.' One end of a spiral spring 602 is also secured to the shaft GM and the other end thereof is secured at 603 to the base 604 upon which the elements of theswitch are mounted. The motor is adapted to rotate in the direction of the arrow A against the resistance ofiered by spring 602 to urge arm 53 in engagement with contact 51. When power is cut off to motor 60, spring 602 rotates shaft 60| in the opposite direction until arm 53 engages contact 62. The arm 53.,

obviously, is insulated from shaft 60|- because it torque suflicient to rotate the arm 53' from contact 62 to 51, spring 602 being designed in accordance with the torque developed to limit said rotation to the desired extent and to return the arm to its original position when the power supply to the motor is interrupted.

It is to be understood that equivalent mechanisms may be employed to perform the same function as motor-operatedswitch 54 such, for

example, as a delayed relay or other suitable, electrical device and, therefore, I do not wish to be explained. The arm 66, however, is adaptedlimit this element of my invention to the exact means disclosed;

One terminal of motor 60 is connected by conductor 64 to conductor 34 which is connected through conductor I3 to line 9 of the service mains. The other terminal of motor 60 is connected through conductor 65 to the arm 88 of a switch 61, the operation of which will hereinafter nected through conductor I2 to leg 2 which, in

turn, is connected to line 8 of the service mains. It will be evident by tracing the above circuit of motor 60 that with the armatures of relay II in their normal positions, as illustrated, the motor 60 is connected directly across the service mains 8 and 9. Hence, motor 60 is normally energized and projection 6| urges arm 53 in engagement with contact 51 thereby closing the circuit to relay 3I. Assuming, however, that the power supply fails in the mains 8 and 9, motor 60 breaks the circuit to relay 3| and connects bell 43 in the telephone. circuit.- Hence, the emission of an audible signal is effected in the event a. power failure occurs in the visual signaling or incandescent lamp circuit.

A still further contingency, however, must be considered and that is a failure of the incandescent lamp. In the event the lamp is burned out or removed there will be no current flow through the circuit. This condition, of course, would not be apparent if, for exampla'switch 4 were open. The relay II is therefore adapted upon an energization thereof to interrupt the normal circuit connecting the motor 80 across the mains 8 and 9 and to connect the same in series with the lamp I. This is accomplished by means of the fourth armature I3 of relay II to which is attached. the conductor 69 forming a part of one leg, hereinbefore described, of the motor circuit. Inasmuch as conductor 69 is connected to both armature I0 and 13, the circuit through conductor 12 will be broken by armature 10 upon an energization of relay II and armature I3 will engage a contact 14. A conductor I5 connects contact I4 with conductor I. Hence, when the armwere burned out or removed or the lamp circuit.

atures of relay II are picked up, armature I3 thereof connects motor 60in series with the in candescent lamp I, the filament of which completes the motor circuit. The motor 60, however, does not consume suificient, current to cause incandescence of the lamp. Obviously,'if lamp I defective, motor '60 would be unenergized thereby opening the circuit to relay 3| and completing the bell circuit through its actuation of the contact arm 53. From the foregoing it is apparent that my device is designed and adapted to prosaid lamp and in parallel with motor I50. Hence,

when a direct circuit to the lamp is completed through the bimetallic arm 22, motor 60 is shunted. The spring 602 of the motor, however, is designed slowly to return arm 53 and the time required thereby to rotate said arm fromconvlamp circuit to line 8 of the service mains.

tact 51' to contact 82 is predeterminately fixed at an interval greater than that during which the bimetallic arm 22 maintains the motor shunted.

Hence, though the current intermitting device I! operates to produce an intermittent illumination of lamp I, motor 60 will not be deenergized a suflicient length of time to effect an operation of the bell. I

As hereinbefore stated, it is desirable to continue the emission of the visual signal after an initial operation thereof is effected in response to a flow of signaling current in the telephone lines. This is accomplished by means ofa locking interconnection between relay II and the transformer 36. A conductor 16 connects a-fixed contact 11- of a thermostatic switch, indicated generally at 18 with conductor 29 which leads to one terminal of the primary winding of transformer 26.- Disregarding for the moment the function of thermostatic switch 18 and assuming that contact 11 is in its normal position in engagement with a movable contact 19, a circuit is completed through said switch from contacts 11 and I9 through the arm thereof with which contact I9 is electrically connected, to terminal 8| of the switch. Terminal 8| is connected through conductor 82 to a contact 83 of relay II. This circuit constitutes a locking circuit for the relay II. Assuming relay 3I is energized and connects the primary 2! of transformer 26 directly across the mains8 and 9; relay II will be energized through the secondary 25 thereof.

Upon an energization of relay II, armature I2 lighting circuit to lamp I as hereinbefore described. Armature I2 also serves to establish the above described circuit. In other words, an energization of relay II causes armature I2 to engage contact 23. Current, therefore, flows from line 9 of the service mains through conductors -13, armature I2 and contact 83, conductor 82, switch arm 80, contacts 19 and TI, conductors I8 and 29, primary winding .21 of transformer 26, conductor 28 and leg 2 of the It is evident that, inasmuch as armature I2, when in engagement with contact 83, connects transformer 26 across the mains 8 and-9 and the secondary of the transformer feeds the coil of relay II, said-relay will continue to be energized when and after the armature is once picked up. Hence, a momentary operation of relay 3| in response to an energization of the telephone mains effects a continued operation of the visual signaling circuit.

In order to effect a discontinuance of the visual signal-emission, I have provided the thermostatic switch I8 which is adapted to limit the operation of the signaling circuit to a predetermined time interval. In the embodiment illustrated, however, the switch 18 is designed and adapted to perform a double function. As illustrated, switch 18 is adapted after a first prede termined time interval of operation of the signaling circuit to connect the bell in the telephone circuit and after a further interval of time to interrupt both the audible and visual signaling circuits and to restore the normal electriclighting circuit.

The thermostatic switch I8, as hereinbefore partially described, comprises terminal 8I to which is connected in electrical engagement a bimetallic arm 8|). A wire 84 of suitable ohmic resistance is coiled around and insulated from arm 80, one end of the coil being connected to terminal 8I and the other end connected through conductor 85 to conductor 28. Am 80 bears an insulating block 86 which is adapted to engage arm 66 of a second switch 61 hereinbefore described.

The resistance coil 84 is designed to radiate sufficient heat to cause bimetallic arm 88 to warp a predetermined distance during a predetermined time interval. The switch is so designed that a movement of arm 80 upwardly, as viewed in the drawing, will first move arm 66, through the medium of block 86, away from contact 68 and thereafter disengage contacts 11 and 19.

It will be noted that when armature I2 of relay II is operated to connect transformer 26 across the mains 8 and 9, said armature also connectsresistance coil 84 across the mains in parallel with the primary winding of the transformer. The circuit of the resistance coil comprises conductor I3, armature I2 and contact 83, conductor 82, terminal 8|, resistance coil 84, conductors 85 and 28 and leg 2 of the lighting circuit. Hence, when transformer 26 is energized coil 84 is also energized and aftera predetermined interval'of time depending upon the resistance of the coil, bimetallic arm '80 commences to warp. It will be remembered that when transformer 26 and coil 84 are connected in circuit, the motor of switch 54 is connected in series with lamp I through switch,arm 66 and contact 68 of switch 61. Hence, when arm 88 of switch 18 has moved a predetermined distance switch 61 is .opened thereby opening the circuit to motor 69. With motor 60 unenergized, arm 53 of switch 51 is allowed to engage contact 62 thereby connecting bell 43 in the telephone circuit. At this point both the lamp signaling circuit, that is, the cir cuit including the current intermitting device I1 in series with lamp I, and the bell circuit are es- 40 tablished and a simultaneous visual and audible signal emission is effected. v

After opening switch 61, the bimetallic element or arm 86 continues to warp until contacts 11 and 19 are disengaged. When this occurs, one 45 leg of the circuit to the primary of transformer 26 is opened. Said leg includes conductor I3, armature I2 and contact 83 of relay I I, conductor 82, terminal 8|, bimetallic element 88, contacts 11 and 19 and conductors 16 and 29. A separa- 50 tion, therefore, of contacts 11 and 19 opens the circuit to the primary of transformer 26 and relay II becomes deenergized thereby interrupting the circuit through the current intermitting device and lamp I and restoring the normal light- 55 ing circuit. This operation of relay I I, of course, reconnects themotor 60 of switch 54 across the service mains 8 and 9. 4 The foregoing illustrates the means I have employed which is adapted automatically to limit 60 the time interval of operation of the lamp signaling circuit. I have also provided means operable when the telephone talking circuit is closed to interrupt the operation of the signaling circuit. This means comprises a relay 81, the coil of which is connected through conductors 88 and 89 to terminals 35 and 31, respectively, of the subscriber's station. An induction cofl 98 is connected between terminals 35 and- 4| and aconduetor 9| connects terminal 4| with one contact 92 of the telephone hook switch indicated genorally at 93. The hook 94 is connected through conductor 95 to one terminal of the transmitter 96 and the other terminal of transmitter 96 is connected through conductor 91 to terminal 39' 77 and the telephone trunk line 39 as illustrated. v

Hence, when the receiver 98 is removed from its hook 94, as illustrated, the talking circuit will be closed and it will be seen by tracing the circuit of relay 81 that it will be energized. The circuit is as follows, starting from trunk line 39 6 and terminal 39'; conductor 91, transmitter 96, conductor 95, hook 94 and contact 92 of hook switch 93, conductor 9|, terminal 4|, induction coil 90, terminal 35, conductor 88, relay 81, conductor 89 and terminal 31 to which trunk line 48 is connected. An energization of relay 81 causes the armatures 99 thereof to engage contact I00. Armature 99 and contact I08 are connected through conductors Illl and I02, respectively, to conductors 24 and 2 which connect the relay II to the secondary of transformer 26. An operation, therefore, of relay 81 short circuits the secondary of transformer 26 thereby rendering the relay II inoperative. Hence, when the subscriber answers the flashing lamp signal by removing the telephone receiver, relay 81 is energized thereby effecting a discontinuance of the lamp signaling circuit and the reestablishment of the normal lighting circuit.

From the foregoing description of ,nrv invention in its preferred form, it is evidentthat a visual signal may be efiected in response to an energization of a telephone circuit, or, at the will of the subscriber, an audible signal or a simultaneous emission of both types of signals may be efiected. As hereinbefore disclosed, the visual signal transpires when the unlighted lamp I is intermittently illuminated or the steadyilluminationof the lamp ceases and an intermittent illumination thereof occurs. Furthermore, this visual signal is maintained for a definite interval of time after which an audible signal is produced and thereafter, the operation of both sige naling devices is automatically terminated. If, on the other hand, the signal is answered by the subscriberin due time, the closing of the telephone circuit efiects a discontinuance of the signaling device or devices in the same manner as the bell is silenced in the present telephone systems by a lifting of the receiver. In addition, my invention, though employing a separate source of supply for the incandescent lamp from that supplying the telephone circuit, insures, through the medium of the motor-operated switch 54, an operation of the bell in the event the lamp fails to-function or its circuit is defective'. Thislatter feature of my invention is very desirable inasmuch as the maintenance of a continuous and uninterrupted service is of prime importance where telephone circuits and apparatus are concerned.

It is to be understood that I not limited to the various electrical means illustrated and described as incorporated in the circuits of my invention nor to the-precise circuits disclosed in order to form an operative device of the character described, but equivalent means and circuits may be substituted for those illustrated with comparable results. While I have, there-. fore, described my invention in its' preferred embodiment, it is to be understood that the specific means disclosed together with the. ar-

rangement of the circuits embodying the same are merely illustrative and that the words which- I have used are clescri ntivev rather than limita tive. Hence, changes within the purview of the appended claims may be made without departing from the true scope and spirit of my inven-' tion in its broader aspects.

What I claim is:

10 said first mentioned means in series therewith;

whereby upon a failure of operation of said visual signal said first mentioned means will close the circuit to said audible device.

2. In a telephone system, a first electric cir- 15 cuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible device in open circuit but operable upon a failure of current flow therethrough to include the same in said first circuit, means connected in said first mentioned circuit and operable upon an energization thereof for controlling said visual device and connecting said first mentioned means in series therewith, and means for maintaining said controlled second circuit.

3. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible device in open circuit but operable upon a failure of current fiow therethrough to include the same in said first circuit, means connected in said first mentioned circuit and operable upon an energization thereof for controlling said visual device and connecting said first mentioned means in series therewith, and means for maintaining said controlled second circuit during a predetermined interval of time.

4. In a telephone system, a first electric circuit comprising telephone trunk lines and, an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible device in open circuit but operable upon a failure of current flow therethr'ough to include the same in said first circuit, means connected in said first mentioned circuit and operable-upon an energization thereof for controlling said visual device and connecting said first mentioned means in series therewith, means for maintaining said controlled second circuit, and automatic means for terminating said maintained second circuit after a predetermined interval of time.

5. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible device in open circuit but operable upon a failure of current flow therethrough to include the same in said first circuit, means connected in said first mentioned circuit and operable upon an energization thereof for controlling said visual device and connecting saidfirst mentioned means in series therewith, means for maintaining said controlled second circuit, and means connected in said first mentioned circuit for efa second electric circuitincluding a visual sig 7,

aovaeec naling device and means normally energized by said circuit for maintaining said audible signaling device in open circuit but operableupon a failure of current fiow therethrough to include said audible device in said first circuit, and means connected in said first mentioned circuit and operable upon an energization thereof for effecting a series circuit through said first mentioned means and said visual signaling device.

7. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual'signaling device, a switch, a normally open shunt circuit around said switch and means for maintaining said audible device in open circuit, and means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit; said first mentioned means being operable upon a failure of operation of said visual signal to close the circuit to said audible device.

8. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith,

a second electric circuit including a visual signaling device, a switch, a normally open shunt circuit around said switch and means for maintaining said audible device in open circuit but operable upon a failure of current fiow there-- cuit comprising telephone trunk lines and an audible signaling device connectible therewith, a

second electric circuit including a visual signaling means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit, means for maintaining the open circuit through said switch and the closed shunt circuit, and means for determining the maintained circuits.

10. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device, a switch, a normally open shunt circuit around said switch and means for maintaining said audible device in open circuit but operable upon a failure of current flow therethrough to. include said audible device in said first circuit, means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit, means for maintaining the open circuit through said switch and the closed shunt circuit, and automatic means for determining said maintained circuits after a predetermined interval of time.-

11. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device, a switch, a normally open shunt circuit around said switch and means for maintaining said audible device in open circuit but operable upon a failure of current fiow therethrough to include said audible device in said first circuit,- means connected in said first mentioned circuit and operable in response to an energization thereof for opening the circuit through said switch and closing said shunt circuit, means for maintaining the open circuit through said switch and the closed shunt circuit, and means connected in said first mentioned circuit for effecting a termination of said maintained circuits.

12. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device, a switch, a normally open shunt circuit around said switch, means normally energized by said circuit for maintaining said audible signaling device in open circuit but operable upon a failure of current fiow therethrough to include said audible device in said first mentioned circuit, and means connected in said first mentioned circuit and operable upon an energization thereof for opening the circuit through said switch, closing said shunt circuit and effecting a series circuit through said first mentioned means and said visual signaling device.

13. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including an incandescent lamp and a current intermitting device connectible therewith, means connected in said second circuit for maintaining said audible ,signaling device in open circuit but operable upon a failure of current fiow therethrough to connect the same in said first mentioned circuit, and means connected in said first mentioned circuit and operable in response to an energization thereof for connecting said current intermittlng device in said second circuit and connecting said first mentioned means in series with said lamp.

14. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including an incandescent lamp, a switch, a normally open shunt circuit around said switch having a current intermitting device connected therein, means connected in said second circuit for maintaining said audible signaling device in open circuit but operable upon a failure of current fiow therethrough to coni nect the same in said first mentioned circuit, and

means connected in saidfirst mentioned circuit and operable in response to an energization thereof'for opening the circuit through said switch and closing said shunt'circuit.

15. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible signaling device in open circuit but operable upon a failure of current fiow therethrough to connect the same in said first mentioned circuit, means connected in said first mentioned circuit and operable in response to an energization thereof for controlling said visual signaling device, and timing means operable after a predetermined interval of controlled operation of said visual device for connecting said audible device in said first circuit.

- 16; In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for'maintaining said audible signaling device in open circuit but operable upon a failure of current flow therethrough to connect the same in said first mentioned circuit,

'means connected in said first mentioned circuit and operable in response to an energization thereof for controlling said visual signaling device, and means operable after a first predetermined time interval of controlled operation of said visual device for aiiecting an operation of said audible device and operable after a second, predetermined time interval for terminating the operation of both signaling devices. I

17. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling-device connectible therewith, a second electric circuit including an incandescent lamp, a current intermitting device and means for maintaining said audible signaling device in open circuit but operable upon a failure of current flow therethrough to connect the same in said first mentioned circuit, means connected in said first mentioned circuit and operable in response to an energization thereof for con-' ,necting said first mentioned means in parallel with said intermitting device and in series with said lamp, means for maintaining said series and parallel connections, and timing means operable after predetermined intervals of time respectively for opening the circuit through said first mentioned means and effecting a discontinuance of said maintained circuit.

18. Ina'telephone system, a first electric circuit comprising telephone trunk lines and an audiblesignaling device connectible therewith, a

. said audible signaling device and means for determining the operation of said audible signaling device and the controlled operation of said visual signaling device.

19. In a telephone system, a first electric circuit comprising telephone trunk lines and an audible signaling device connectible therewith, a second electric circuit including a visual signaling device and means for maintaining said audible device in open circuit but operable upon a failure of current flow therethrough to connect the same in said first circuit, means'connected in said first circuit and operable in response to an energization thereof for controlling said visual signaling device, means, for maintaining the controlled operation of said visual device, timing means connected in said second circuit and operable after a first, predetermined time interval of operation of said visual device for connecting said audible device in said first circuit and operable after a second, predetermined time interval for determining the operation of both signaling devices and means connected in.said first circuit for determining the operation of said signaling devices.

circuit whereby an independent or joint operation of said signaling devices is effected.

21. In a telephone system comprising a subscribers station, the combination with an audible signaling device, a visual signaling device and manually controlled means for selecting and operatively associating either of said signaling devices with the telephone circuit for operation in response to the flow of signaling current therein, of means connected in series with said visual signaling'device and operable upon a failure of said visual device when it has been selected for operation for effecting an operative association of said audible device with said circuit.

22. In a telephone system comprising a subscribers station, the combination with a bell, an incandescent lampand manually controlled means for selecting and operatively associating either said bell or lamp with the telephone circuit for operation in response to the flow of signaling current therein, of means connected in series with said lamp and operable when said lamp has been selected and upon a failure of illumination thereof when signaling current flows in said telephone circuit to effect an operative association of said bell with said circuit.

ANTHONY J. PARISSI.

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