US2114535A - Gas arc lamp - Google Patents

Description

April 1933- K. F. J. KIRSTEN 2,114,535

GAS ARC LAMP Filed Oct. 24, 1933 2 Sheets-Sheet 1 l2 7 INVENTOR fU/?7' EJ." MR.) TEN Z BY ATTORNEY April 1 1938. K. (F. J.v KIRSTEAN I 2,114,535

GAS ARC LAMP Filed Oct. 24, 1933 2 Sheets-Sheet 2 INVENTOR Myer f: J f/RsTEN ATTORNEY Patented Apr. 19,. 1938 PATENT OFFICE 2,114,535 GAS ARC LAMP Kurt F. J. Kirsten, Seattle, Wash., assignor to Kirsten Lighting Corporation, a corporation of Washington Application October 24, 1933, Serial No. 694,981

3 Claims.

This invention relates to the art of gaseous conduction-lamps and has reference more particularly to a novel electrical circuit for the kindling and operation of a gas are lamp.

Heretofore, in the art of gaseous conduction lamps or luminous tubes containing rare gases or metallic vapors, the chief difliculties have been in the complexity of the electrical circuit and of the equipment required in connection therewith. Even the most recent achievements in the field of gas are tubes embrace the following auxiliary devices:

First.--Directly or indirectly heated cathodes coated with a metallic oxide. Second.--A source of electrical energy for heating the cathodes; usuallyin the form of some special low potential windings superimposed upon the main transformer which energizes the are.

Third.A high frequency oscillator or Tesla.

coil, energized from the main circuit for starting the arc.

Fourth.-A ballasting impedance which stab lizes the arc orwhich, in series with the arc of negative resistance characteristics, gives the circult as a whole positive resistance characteristics.

Fifth-Thermostats which retard the imposition of are potential upon. the electrodes until after the cathodes have been brought up to proper heatand which also retard and limit the functioning of the Tesla coil to the proper period of its operation.

Sixth-Relays which, delayed by the thermostats, close the main arc circuit and open the Tesla coil circuit at the proper time and which 35. shunt out the thermostats so that they may assume their normal initial setting for again repeating this starting cycle of operations should the line potential drop or be cut off due to circuit disturbances.

40 The cost of the above equipmentand the added expense of its maintenance and skill required for its assembly have stood in the way of introducing the luminous arc lamp into the field of general illumination in competition with other sources of light, such as the tungsten lamp, or in the field of advertising with the high voltage glow tube which is now used extensively in all parts of the civilized world and which owes its success to the .simplicity of its circuits and small amount of 50 auxiliary equipment necessary to operate it.

With respect to the high voltage glow tube, the operating equipment consists only of a suitable impedance in series with the tube circuit to give the tube a positive resistance characteristic. 56 Usually this impedance is incorporated in the transformer which has a secondary potential sufficiently high to start the lamp.

In view of the above stated facts, it has been the object of this invention to simplify the luminous arc tube and its supplementary circuits so 5 that it compares favorably in cost and maintenance with the simple glow tube and its circuits.

It is also an object of this invention to provide a'novel lamp circuit whereby use of the usually 10 employed Tesla coil and associated relays are eliminated; which also eliminates the use of costly external thermostats and their heating coil and finally, the production of a highly efficient arc lamp at a cost comparing favorably with that v 15 of the glow tube.

Other objects of the invention reside in the details of construction of the circuit, the electrodes and the mode of operation of the lamp, as will hereinafter be fully described.

The simplification of the circuit of the luminous arc tube is made possible chiefly through use of the special cathode construction described and illustrated in my pending application filed on August '7, 1933 under Serial Number 683,985. 25

' This cathode is constructed so that it is energized by' the arc current itself instead of by special auxiliary circuits. In connection. with this particular cathode I associate bi-metal thermostatic strips in the electrode construction 30 whereby the arc current is shunted through a conductor which, externally of the tube, connects the heating elements of the cathodes in series. Thus, the electrodes are heated as soon as thecircuit is closed and when the cathode heat is sufliciently high, the bi-metal strip warps from the heat and. breaks the short-circuit of the arc. This sudden opening of the short-circuited arc path and of the impedance creates a rise of potential across the arc path which is suiiiciently high to kindle the are.

In accomplishing the various objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, where- Fig. 1 is a view diagrammatically illustrating the present lamp and its circuit in its simplest form.

t Fig. 2 similarly illustrates the lamp and anothercircuitof simple form.

Fig. 3 is a diagrammatic illustration oixth'e present lamp and its circuit including control equipment which will insure most satisfactory an external thermostat.

Fig. 6 is a diagram of another alternative construction employing an external thermostat and relay.

Referring more in detail to the drawings- In each oi the several views i designates a sealed transparent tubular vessel of glass or other suitable material filled with-a rare gas or metallic vapor, or a combination of gas and vapor which is the carrier for the luminous arc. At its opposite ends the tube 8 has enlargements 2'2' shaped to best accommodate the terminal electrodes of the lamp; which, respectively, are designated in their entirely by reference numerals 3-6.

The electrodes 33' preferably are in accordance with the construction illustrated and de-.

scribed in my application filed August 7, 1933 under Serial Number 683,985, and each comprises an indirectly heated cathode enclosed by a heat conserving shield. More specifically described, the cathode consists of a tubular metallic shell 81: within which is a heater coil 5. The outer end of the coil is electrically connected with the, shell 8a and at its inner end is connected with a terminal wire 8 which is sealed through the end wall of the lamp tube. The heat conserving shield which encloses the cathode is designated by nu,- meral 8b and this is a cylindrical, metallic piece larger than the cathode and supported by a sealed .in wire I used as a terminal only for processing the luminous tube. The shield 3b has electrical connection at 30 with the outer end of the oath-- ode shell id for the purpose fully disclosed in the above mentioned application.

In accordance with the present invention, as illustrated in Figs. 1, 2, and 3, in each electrode a bi-metal strip 5, functioning as a thermostatic element, is welded or otherwise fixed at one end to the heat conserving shield 3b and the movable end of this strip normally makes contact with a sealed in terminal connection .8. The terminal 6 at one end of the tube and its corresponding terminal 8' at the other end of the tube are electrically connected by a conductor 9.

In the construction of the lamp of Fig. l, standard line potential from a one hundred ten or two hundred twenty volt main may be applied by the closing of a switch i2, to the terminal connections 88' of the lamp; these terminals being connected to the switch by the conductors 8a and 8b. In this simple construction a current limiting reactance. designated at i 8, is included in the conductor 8a and this is so designed thatthe lamp operates at the desired current and that the current is not too large for the cathode heaters when the arc is shunted by the wire 9 as will presently be understood.

The circuit of Fig. 2 differs slightly from that. of Fig. 1 in that the application of electrical potential on the terminals 8-8 from the main.

line is through a transformer consisting of an iron core ll with a magnetic shunt l5 which gives the transformer a high internal reactance. It in-.

ciudes' also the primary winding l6 and autorlous kinds of im- The-lamp circuit of Fig. 3 is an elaboration of r the simple forms shown in Figs. 1 and 2. In this arrangement the terminals 8 and 8' are connected to the terminals of the secondary winding of a current limiting transformer Ii. The primary winding of this transformer is connected to the power circuit through switch i2. Also in this arrangement the terminals 6 and 8 at one end and theterminals 6' and 8' at the other end are serving shield 31) surrounding the cathode, the

current will flow through the shell and thermostatic strip 5 to terminal 6, thence through conductor 9 and impedance 8a to the terminal 8'; thermostat 5; through electrode 3' to terminal 8' and back to the transformer secondary. The magnitude of this current depends upon the total impedance of the secondary circuit, that is, upon the resistance of coils i, the shunt impedance 9a and the internal reactanc of transformer ii.

The internal reactance oi the transformer is so proportioned that the short-circuit current of the secondary is only slightly larger than the normal operating current of the lamp after the arc is established.

A short time after closing the switch it, the heater coils 4, will bring the cathodes to incandescent glow and by radiation of heat to the shields, the bi-metal strips 5 will warp-iso that their contacts with terminals 8-5 are broken.

This sudden opening of the circuit through imthe arc in the tube will re-kindle automatically.

since, upon the circuit failure, the cathodes immediately lose their heat and the thermostats 5 close against terminals 8-6, thus re-establishing the normal starting conditions of the tube. It the voltage fluctuation in the supply circuit isso rapid that full potential again exists on terminals 8 of the tube -before thermostats 5 have time to close upon terminals 6-6, the gas in the gap between the thermostats and their respective contacts becomes ionized allowing approximately normal current to pass through the impedance shunt 99a and heater coils l with the result that the cathodes are brought again to normal emission and the arc is re-estabiished.

The operation of the lamp of Fig. 2' is sub- -'stantially like that of Fig. 3. It will be observed that in the arrangement of Fig. 2 there is no impedance interposed in the conductor -8 and This are current is of sufficient magnitude that there are no condensers shunting the terminals 6-8 and 6'-6'. It has been established that the impedance may be omitted and the terminals 6-6 connected with a wire of suitable size except in cases where the reactance of the transformer is such that the secondary shortcircuit current is so large that the cathode heater wires become overheated.

The condensers Iii-Ill of Fig. 3 are not necessary in normal circuits but are very effective in kindling the arc at considerably lower voltages than is possible without them. Also, they eliminate the current drop in a mercury vapor tube which always occurs during .the first minute after the arc is struck. Incidental to this current drop, the arc voltage also rises and it is this maximum are potential for which the transformer Ii has to be designed. Hence if this potential rise is prevented by use of a condenser 16, the same transformer can maintain an arc during its initial burning stages in a considerably longer tube.

Therefore, the use of condensers l0-lll' as in Fig. 3 has the advantage of greater tube footage for a given transformer, an increased power factor for the tube circuit, and assures a more positive kindling of the are.

When omitting the impedance 9a and condensers l0lli of the circuit of Fig. 3, the only equipment necessary for the operation of the tube is the provision of a transformer with sufficient internal reactan'ce to limit the short-circuit current of the secondary to approximately the same magnitude as the normal operating current of the arc. Hence, the circuit is precisely as simple as that of the high voltage glow tube. In this connection, it will now be apparent that by the simple addition to the electrode of my above mentioned co-pending application, of a thermostatic element for delaying striking of the arc until the cathodes have become heated, and'by the addition of a conductor joining the two electrodes of the tube, the glow tube is changed to arc. performance.

In an alternative construction, as disclosed in Fig. 4. the conductor 9 is located internally of of the lamp tube and connects at its ends with metal hooks 20 supported by insulation 2| from the shields 3b and adapted to be connected electrically with theshield by a bi-metal thermostatic band 23 attached to the shield.- In this type, the conductor serves by corona discharge to ionlze the gas along the arc path to stimulate the formation of the are when the shunt connection along conductor 9 is opened.

In another modification, as shown in Fig. 5, I locate a thermostatic switch 25 in the conductor 8 externally of the tube; the conductor in this instance has direct connection through the terminals 6-6 with the shields 3b. Conductors 26-21 lead from the secondary of transformer Ila to terminals 8-6' and a coil in conductor 26 applies heat to the thermostat to open the. circuit through conductor 9 after the cathodes have become heated. Also, a condenser, as at 2|, may be provided to shunt across the switch to aid in starting the are, especially in long tubes.

Fig. 6 discloses still another alternative construction in which the shunt connection 9a. between the electrodes is exterlorly of the tube and is completed through the. armature ill of a relay 3|. The core 32 of the relay is surrounded by a coil 33 connected at one end by wire. 34 to a thermostatic strip 36 and at its opposite end by secondary with terminal 8'.

In using this type of lamp, at the start, the

a wire 36 to a circuit wire 31 that leads from the lamp terminal 8 to a contact 38 adapted to be engaged by the thermostatic strip 35. A wire Ill from one side of the secondary of a transformer ll forms aheating coil 42 about the thermostatic strip and fastens to the base of the strip. A wire 45 connects the other side of the shunt connection is closed through armature 3|, thus connecting the heating elements in series in the lamp circuit. Current also flows through coil 42 to wire 31 by reason of lesser resistance than is placed in the relay circuit. The coil 42 becomes heatedand ultimately causes the thermostatic strip 25 to disengage terminal 38 thereby causing current toflow through relay coil and energizing the relay to open the circuit through the conductor 9a thereby causing the arc to be established in the lamp.

It will be quite apparent that in the present arrangement, especially of Figs. 1. 2, and 3, an arc lamp of simplified construction is provided. It is a lamp that can be made and maintained in operation at a relatively small cost especially in comparison with present day gas are lamps. It is a lamp that compares favorably with the common glow lamp in cost of construction and maintenance but which is materiallybetter from the standpoint of illumination. The cathodes are energized not by special auxiliary circuits,

I but by the arc circuit itself, and by use of the Having thus described my invention, what I claim as new therein and desire to secure by Letters Patent is 1. A lamp of the character described comprising a sealed, transparent tubular vessel containing an ionizable gas and provided within its opposite ends with electrodes, each with a terminal extending to the exterior of the tube, a source of alternating current. potential with connections from opposite sides thereof, respectively, to said electrode terminals, each of said electrodes including a heating element in series with the lamp circuit, a conductor extending between the electrodes exteriorly of the tube and having terminals entering the tube, an impedance element in said conductor, condensers shunted across'the terminals of said electrodes and of said conductor and thermostatic strips associated with each electrode and operable at'a predetermined degree of heat therefrom to open the circuit connection provided between the electrode and said canductor.

2. A lamp of the character described comprising a sealed, transparent, tubular .vessel, containing an ionizable gas and provided within its ends with electrodes; each with a terminal con- 'nection extending to the exterior of the tube; a source of alternating current having connections leading to said terminals and through which. electrical potential may be impressed on the electrodes to maintain an arc in the lamp; each of said electrodesincluding a cathode containing a heating element and a heat conserving shield surrounding the cathode and electrically connected thereto, a'conductor exteriorly of the tube '0! the electrodes, thereby to join the heating elements and shields in series with the lamp circuit; said thermostatic elements being adapted site terminals of the lamp, a conductor exterior- 1;! 0! the tube shunting the arc path between the electrodes and including a solenoid activated switch, a thermostatic element for closing the supply circuit, a heating coil in series with the thermostatic element and supply circuit for heating the element to open the circuit and an energizing coil for the switch through which the supply current is shunted by the opening of the circuit through the thermostaticelement, thereby to open the switch in the electrode connecting m conductor.

- 7 KURT I". J. KIRSTEN.

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