US2041610A - Ionic discharge tube - Google Patents

Description

y 1936- T. J. KILLIAN IONIC DISCHARGE TUBE Filed May 8, 1955 mm J v m Uh- /.V a M 5 VI E N R O T T Patented May 19, 1936 PATENT," OFFICE IONIC DISCHARGE TUBE Thomas J. Killian, Seattle, Wash, assignor to Luminous Tube Lighting Corporation, Seattle,

Wash, a corporation Application May 8,1933, Serial No. 670,008

2 Claims. (61. 176-125) The present invention relates to gaseous discharge devices and more particularly to devices of the character generally known as luminous I gaseous discharge tubes.

One of the objects of this invention is to provide a luminous discharge tube or lamp of such a character that the desired initial quality, quantity and efficiency of light produced will remain practically unchanged over long periods of operation of the tube.

Another object of the invention is to provide a gaseous discharge tube or lamp of such a character that the operating efficiency will be maintained substantially unchanged over a long period of time by keeping substantially constant not only the total pressure of the mixture of gases in the discharge tube, but also their partial pressures.

In order that a luminous gas discharge tube using chemically active gases such as carbon dioxide, carbon'monoxide, nitrogen, etc., or using mixtures including one or more of these gases, may have a long life during which the quantity, quality and efliciency of light remain practically 25, unchanged, it is necessary that not only the total pressure but also the partial pressures of the constituent gases remain ,unchanged. While it has been known for many years that carbon dioxide or monoxide will give a fine white light,-

similar to north sky light, due to a very densely filled and well balanced spectrum, I have found that in order to produce this light over long periods of time, it is necessary to maintain the equilibrium of the mixture of carbon dioxide, carbon monoxide, oxygen and various sub-oxides of carbon into which carbon dioxide or monoxide breaks up when ionized.

In any gas filled discharge tube there is a. gradual disappearance of gas which is called "clean up and it has been found that in this clean up various gases disappear at diiierent rates. I have found that an excess of oxygen lowers the efiiciency of the tube more than any other constituent gas and also in a tube using dielectric or condenser electrodes and carbon dioxide that oxygen cleans up more slowly than other gases. Therefore it is impossible to obtain long life and maintain efficiency of atube by merely renewing or supplementing the supply of carbon dioxide since, in so doing, the equilibrium of the mixture is gradually changed and the efilciency of the tube is steadily decreased.

It has been found that in the operation of gaseous discharge lamps, using carbon dioxide, carbon monoxide or other active gases, they will ordinarily change rather rapidly in efiiciency and quality of the light produced. This invention makes it possible to maintain the initial efliciency and quality of light produced over long periods of time, exceeding a thousand hours.

By this invention means are provided whereby large and bulky lamps may also be conditioned for use in a simplified manner.

In carrying out this invention an activator, preferably in the form of porous or finely divided material or material whose area is large compared to its volume, is placed in direct contact with the gas in an ionic discharge tube. Such discharge tubes may be easily and quickly reconditioned in accordance with this invention and proper conditioning of large and bulky lamps of this sort can be effected without employing a baking out treatment.

Other objects and advantages of the invention will be apparent during the course of the following detailed description, taken in connection with the accompanying drawing, forming a partof this specification and in which drawing:

Figure 1 is a somewhat diagrammatic view showing the preferred embodiment of the invention, together with the electrical circuit; Figures 2 and 3 are slightly enlarged views of one of the electrodes on the corresponding respective lines shown in Figure 1; and Figure 4 is a detail sectional view through two of the electrode tubes on an enlarged scale.

In the drawing and wherein similar reference characters designate corresponding parts throughout the several views, the letter A designates the body portion or luminous portion of a gaseous or ionic discharge tube, provided at each end with a dielectric electrode B. A transformer C is indicated having electrical connection with the electrodes B. Means D is shown for maintaining the equilibrium of the gaseous mixture in the tube section.

The tube A may be of any suitable material, size or shape in accordance with the particular use for which the lamp is intended and may be made from any clear glass that is not easily cracked or broken.

The electrodes B may be formed of any suitable glass capable of withstanding ordinary strains encountered in apparatus of this character. Each electrode B comprises a main header 5 sealed to the tube A. A series of preferably L-shaped carrier tubes or headers 6, preferably of less diameter than the main header tube 5, is connected in parallel spaced-apart relation along the length of the header I to project in right angular relation thereto. A series or group of electrode tubes or tips I, which may be of less diameter than the header 6 and extend in parallel spaced-apart relation to one another and to the vertical or long leg of the header, is connected to the short or horizontal leg of each header 6. These groups of tubes or tips I are arranged in parallel planes whereby vertical air spaces are provided between the tubes.

A coating 8 of conducting material, as shown in Figure 4, is applied over the entire or any suitably large portion of the electrodes, and a suitable lacquer 9 may be applied over this materialto insulate the same and minimize static discharge. A terminal wire l0 which is rigidly embedded in the conducting material and lacquer covering is looped about the headers 6 prior to application of the coating 8 to the electrodes. These terminal wires have one end exposed for making connections with the secondary terminals of the transformer C.

The transformer C may be of any suitable type and in the example shown embodies a frame H provided with a primary winding l2 supplied by a source of alternating current I3 ofordinary commercial frequency, and a secondary winding l4 connected by conductors I5 to the terminal wires ID of the electrodes. Arranged between the windings l2 and. I4 are iron cross pieces l6 which serve to provide the proper amount of leakage of magnetic flux and compensate for the capacitance of the dielectric electrodes, so that the power factor may be kept as near unity as is desired. The means indicated at D consists broadly of a device for effecting contact between a properly conditioned porous material or a finely divided material or substance whose area is large compared to its volume and the gas in the discharge tube, thus preserving not only the total pressure of amixture of gases in the tube constant, but also their partial pressures.

This is done in the present embodiment of the invention by placing finely divided or porous material, as indicated at 20, in a small glass appendix or the like connected to the discharge tube at any suitable point and preferably adjacent one of the electrodes. In the example illustrated, this appendix embodies a bulb-like container portion 2| having a small neck or tube 22 which is connected to the discharge tube. One or any other desired number of these appendixes may be connected to the discharge tube at convenient places, such as the ends or intermediate portions. While the finely divided or porous material 20 is preferably placed in an appendix for connection to the discharge tube, the material may be placed in suitable quantities in either the headers 6 or tips I or the tube A, if desired.

The material 20 may be conditioned before it is placed in the appendix in such a way that it will adsorb or absorb large quantities of gas or mixture of gases. The conditioning of the finely divided or porous material may be effected by heating the same to drive oft undesirable vapors or gases, leaving the same in a condition to readily adsorb or absorb the desired gas or gases. How-- ever, it has been found in some cases that charcoal, for example, can be used without any special conditioning. The desired gas or gases may be adsorbed or absorbed by the fin'ely divided or porous material either before or after it is placed in the appendix or before or after the appendix containing it is attached to a lamp tube, simply by bringing the gas into contact with the material.

In operation of the ionic discharge tube embodying this invention; there is a constant exchange of molecules between the gaseous and the absorbed or adsorbed phases whereby the gaseous when there are small quantities of water vapor or other impurities in the discharge tube which would aflect its efficiency, they will be taken up by the material in the appendix after several minutes of running the tube, and will only slightly dilute the gas absorbed or adsorbed in it.

In a comparison test two lamps or discharge tubes consisting of twenty-three feet of 11 mm. tubing with dielectric electrodes similar to those described herein were given identical treatments with the exception that one lamp was provided with an appendix as described herein containing about two or three cubic centimeters of willow charcoal. Each lamp was evacuated and baked for several hours at 300 to 350. C. and was al lowed to remain over night filled with an atmosphere of carbon dioxide. The pressure was then reduced to about 0.2 mm. and the lamps were sealed off. Current was then applied to the lamps and the lamp without the appendix showed signs of decline in fifteen hours of running and went out at the end of approximately twenty-five hours. The pressure in it had dropped to less than 0.02 mm. The other lamp which was provided with the appendix containing charcoal, ran four hundred hours with no apparent change, and when the pressure in this lamp apparently began to drop the bulb 20 of the appendix was gently heated with a small flame and the lamp ran nine hundred additional hours with no perceptible change in efliciency or in quality of light. This heating of the appendix apparently liberated some 'of the adsorbed gas in the charcoal and increased the rate of transfer of molecules between phases.

If a lamp has been sealed off at too high a pressure, cooling the appendix with carbon dioxide snow or liquid air will give the lamp its desired characteristics.

By other methods, but similar to those previously stated, of conditioning the material 20, lamps have been produced which continuously carried electric current of thirty milliamperes and over for more than a thousand hours with a change of any observable variable of less than ten per cent.

The activator 20 of finely divided or porous material may be willow charcoal, lamp black, bone black, activated carbon, platinum black, powdered glass, powdered ceramic materials, etc. The activator material mayalso be in the form of needles, flakes, etc. Although the activator may be used inside of the lamp proper, and has been so used, there are many advantages in having such activating material in an appendix such as D connected to the lamp. Among these advantages are that large numbers of the appendixes can be prepared and conditioned at one time and sealed oif until required; the appendix is not subjected to the variations in temperature which the lamp proper undergoes; the inside of the lamp is keptvfree of any foreign substance likely to impair its efilciency, and lamps the appendix.

In the production of luminous discharge tubes which are too bulky to be baked out, the removal of impurities is a long and tedious process involving numerous rinsings, pumpings and running of the lamps and this process in some instances requires several days or even weeks. By this invention the conditioning of large and bulky discharge tubes may be greatly expedited. For example, a discharge tube lamp which was too bulky to be baked out was conditioned by attaching appendixes similar to that described herein to each electrode of the lamp, pumping the lamp out, gently heating the activated material, then filling the lamp to atmospheric pressure with carbon dioxide and after several hours evacuating it to about 0.2 mm. of mercury. An electric current was then applied to the lamp and at first the lamp was quite pink due to water vapor. After running the lamp for a few minutes, this color had disappeared and shortly thereafter the water vapor could not even be detected spectroscopically and the lamp ran unchanged many hundreds of hours. Other lamps which were similarly treated have run as efliciently as those lamps which have had the best baking-out vacuum treatment.

Numerous tests that have been conducted indicate that the maintenance of pressure and composition of the gases in the lamp system by this invention is not confined to the chemically active gases mentioned above, but is also practicable with all gases and mixtures of gases which are comparatively stable under the action of electrical discharges.

I claim:

1. The process of producing a gaseous discharge lamp which comprises pumping out the lamp, placing an activator that has been conditioned with adsorbed gas in communication with the interior of the lamp, gently heating the activator, filling the lamp to atmospheric pressure with carbon dioxide and after several hours evacuating the lamp to the desired pressure, then applying an operating current to the lamp, and maintaining communication between the interior of said lamp and said activator during normal operation of said lamp.

2. The process which comprises introducing oxides of carbon into a tube for luminous purposes, bringing carbon with adsorbed carbon dioxide into contact with said gases, sealing ofi said tube at a. pressure higher than necessary for luminous purposes and reducing the pressure by cooling said carbon.

THOMAS J.

Images