US2007924A

US2007924A - Short wave length electric lamp

Info

Publication number: US2007924A
Application number: US477306A
Authority: US
Inventors: Ruben Samuel
Original assignee: SIRIAN LAMP CO
Current assignee: SIRIAN LAMP Co
Priority date: 1930-08-23
Filing date: 1930-08-23
Publication date: 1935-07-09
Anticipated expiration: 1952-07-09

Description

y 9, 1935. S.-RUBEN 2,007,924

7 SHORT WAVE LENGTH ELECTRIC LAMP Filed Aug. 25, 1930 2 Sheets-Sheet 1 July 9,1935. 5, RUBEN SHORT WAVE LENGTH ELECTRIC LAMP 7 Filed Aug. 25. 1930 2 Shets-Sheet 2 INVENTQR ATlfORNEY Patented July 9, 1935 I UNITED STATES PATENT OFFICE SHORT WAVE LENGTH ELECTRIC LAMP Saniucl Ruben, New Rochelle, N. Y., assignor to Sirian Lamp Company, Newark, N. J., a corporation of Delaware Application August 23, 1930, Serial No. 477,306

6 Claims. (Cl. l'lfi l) diation which have been available aresun-light,

the arc-light, and the mercury vapor lamp. The sun-light is too variable to be considered industrially. Arc lights are also variable in operation and costly to operate due to the continual consumption of the-electrode material. Mercury vapor lamps besides having a high initial cost require direct current for operation and have a short life due to consumption of the electrode surface. These also require auxiliary equipment.

It is one of the objects of the present invention to provide a short wave length electric light which may be operated on commercial circuits without any auxiliary equipment and with low power consumption and long life.

Another object of the invention is to provide a device for. producing short wave length light which arises from a uniform electrical discharge v with high intensity and the steadiness of a fila- 25 ment.

Another object of the invention is to provide a short wave length light which may be operated on commercial lighting circuits and which is made up like an ordinary light bulb so that it may be screwed into any standard socket.

Other objects of the invention and objects ;relating to the construction and assembly of the various parts will be apparent as the description thereof proceeds.

The invention has been illustrated in the accompanying drawings in which:

Fig. 1 is a side elevational view of one embodiment of my improved low wave length electric light;

Fig. 2 is a longitudinal enlarged view partly in section of one end of one of the lighting elements;

Fig. 3 is a side-elevational view of a modified form of the invention; and

Fig. 4 is a sectional plan view of the construction shown in Fig. 3 taken on the line 3-4 of Fig. 3.

Referring now more specifically to the drawings the construction of the lamp shown in Fig. 1 comprises an envelope lll preferably of quartz glass, borosilicate, or other material which will not absorb short wave length radiation to an appreciable extent and which may be formed integral with a press II for supporting the various elements of the lamp. A straight support rod l2, may be sealed in the press II and may extendupwardly 'may have its upper end attached to the support l3 This drives out the binder in the electron emitto a point adjacent the top of the envelope where it may be bent at right angles to form a support l3 for the light emitting element. A glass tube ll may be provided around the support l2 extending between the-press H and the angular portion l3. 5 Another support rod I5 may be sealed in the other side of the press I l and may be bent outwardly and upwardly terminating a short distance from the press. An electron emitting element I6 while its lower endmay be attached to the short connector ll of nickel or other conducting material. A second electron emitting element l8 may have its upper end connected to the other end l of the connector l1 while its lower end may be 1 5 connected to a second short connector I9 similar to the connnector ll. Also a third electron emitting element 20 may have its upper end connected to the upper end of the connector I!) and its lower end connected to the' support rod l5 thus 20 placing all three electron emitting elements l8, i8, and 20 in series. All of these electron emitting elements may comprise a coil 2| (see Fig. 2) which may be formed of any desired resistance metal such as molybdenum, tungsten, tantalum, 25. or nichrome wound in a relatively small coil and having the outer surface of the coil coated with an electron emitting material 22 which maybe any of the well known materials used for that purpose such as the oxides of the alkaline earth metal group or any desired mixtures of the oxides or any other material which will have ahigh electron emission efliciency at relatively low 'temperatures.

With the elements constructed as shown in the figure the envelope I0 may be connected by means of a tube in the usual manner to an exhaust pump and an oven placed over it to raise the temperature thereof to 350 to 400 C. A curably be obtained. When no more gas is found in the bulb the current may be increased through the filament so that the temperature is slowly raised to aboutv 800 C. with a bright red color.

ting material and other occluded gases which mi ht be present, the vacuum pump withdrawing thesev gases as they are driven out.

When the high vacuum is again obtained the oven may be raised and the filament heated again for a moment to slightly less than 1200 C. to drive out more gases which are immediately removed from the envelope by the vacuum pump. Then the pump may be shut off and the current turned off and a slight amount of an inert gas, such as neon at about mm. pressure, may be admitted to the bulb and the filament current turned on again and gradually increased. Spots of localized discharge having a reddish'color will then appear on the elements or support wires and will gradually spread till a diffused glow completely fills the bulb. This process activates the electron emitting coating and may be maintained until the discharge is uniform throughout the entire bulb which usually takes less than ten minutes. During this time the current on the filament should not be raised too high so that the coating on the filament will not be destroyed or thrown off from the filament. If white discharge spots appear on the filament or support rods it is an indication that there are more gases or vapors within the bulband the bulb should again be exhausted and the whole process of activation repeated.

When the activation is completed the filament temperature may be raised for a moment to about 1400" C. and then the vacuum pump again connected and the gas pumped out to remove any undesirable gases which may have been thrown off during the activation process. The pump may then be turned off and about 5 mm. of helium gas and 10 mm. of neon may be added to increase the conductivity to cause the discharge to occur in all directions. Then enough argon gas may be added until all ionic discharge stops except an intense one around the filament and in the same direction as the filament. This discharge will vary with the light intensity and the temperature of the emitting oxides. About mm. of argon has been found to be sufiicient to confine the ionic discharge along the length of the filament. The bulb may then be sealed off.

A metal vapor may be introduced into the bulb by providing a small container 25 formed of metal plates and supported by a rod 26 which may be welded to one'of the support rods, as the rod l6, and placed down in the neck of the tube where it may be heated independently of the other elements. In the container I may provide a small amount of magnesium and a salt preferably a chloride of one of the metals desired to be used in the bulb. When the magnesium is fiashed after the bulb is sealed off to clean up the interior of the bulb it reacts with the metal salt liberating the free metal which condenses on the walls of the bulb. Thus where I desire to use mercury vapor in the bulb I provide mercuric chloride and magnesium in the container and when flashed the mercury is liberated leaving magnesium chloride which is stable and does not interfere with the operation of the lamp. The

- mercury condenses on the walls of the envelope and evaporates again when the envelope is heated when the lamp is used.

Mercury vapor used in connection with argon as described above produces an ultra-violet light which is absolutely steady and has no deteriorating effect upon the elements or other parts of the bulb. Other radiations may be produced if desired by using calcium, caesium, or rubidium va- -tance material.

por with the helium, the mixture of rubidium and argon giving an infra-red radiation. Not only is the discharge intense and practically uniform without any deterioration of the filament or coating but the temperature of the filament is maintained relatively low and the light is greatly increased over anything heretofore known or used.

When the leading-in wires 23 and 24 are connected-across the lighting circuit the temperature of the electron emitting elements I6, l8, and 20 is raised and the emission of electrons from these elements apparently causes ionization of the gas in the immediate vicinity thereof which produces a conductive path along the element and permits current to flow through this conductive path forming a discharge or halo which produces the illumination.

Where I use the lamp on volts pressure I may prefer to use the three separated elements shown but a single element may be used if desired with lower voltages.

Note should be made of the fact that the glass tube M on the rod 12 extends to the press II. This prevents any tendency to arc between the lower end of the element 20 and the opposite potential rod l2 and necessitates any arcing tendency to be along the length of the element and as this length is divided into three parts there is a third of the potential difference across each individualelement and arcing is prevented.

While I have shown three separate elements it will be understood thatit may be possible to use a single coil filament extending from the support l5 to the straight portion I3 of the rod [2, and although I have shown coil filaments it may be preferable to use single straight wires of resis- I may prefer to use the coil in order to increase the potential drop per unit length of element.

I may desirev to reflect the short wave length light in a given direction and if so the construction of. Fig. 3 may be used. Here the envelope 2! may be supported on the press 28 which contains support rods 29 and 30 similar to the support rods I 2 and I 5 already described and a plurality of electron emitting elements 3|, 32, and 33 may be connected between the support rod 30 and the upper end 29' of the support rod 29 in a manner similar to that already described with a heavy conductor 34 between the elements 3| and 32, and another 35 between

elements

32 and 33. This construction is similar to the construction of Fig. 1 except that the upper end 29 of the support rod 29 may be made somewhat longer than the end l3 of the support rod l2 to provide a greater space between the elements and the glass rod 36 which covers the support rod 39. Between the elements and the support rod I may provide a. curved reflector 31 made of aluminum which has been electrolytically oxidized on its inner surface. Aluminum is preferred because it appears to be one of the best reflectors of short wave length light when electrolytically oxidized. The aluminum reflector may be provided with a pair of nickel eyelets 38 at the lower ends thereof which may be welded to two

support rods

39 and 40 which may extend downwardly and may be sealed in the press.

The reflector may be electrolytically oxidized by using it as the anode in an electrolytic bath of about 3% of borax and 10% of boric acid making about a 10% solution of the mixture in water. Two hundred volts may be applied across the circuit and about of an ampere per square centimeter of aluminum surface with the electrolyte at about 80 C.

While th invention has been shown and described in onnection with a particular type of electron emitting element it is evident that other elements may be used such as a single filamentary wire coated with electron emitting material or such a. wire or a coil coated intermittently may be used. .A coil of resistance wire may also have individual turns coated with the material if desired.

Many modifications of the invention may be resorted to without departing from the spirit I thereof, and I do not therefore desire to limit myseli to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim is:

1. In an electric lamp comprising an envelope, an electron emitting element containing an oxide of the alkaline earth metals, means to support one end of said element, means to support the other end of said element, a glass tube sub,- stantially completely covering said last mentioned means, and an ionizable gas surrounding said element and having a pressure and breakdown potential of such value as to confine the ionization thereof to the region of said element when said element is energized.

2. An electric lamp comprising an envelope, a high resistance electron emitting element containing an oxide of the alkaline earth metals, means to support one end oi! said element, means to support the other end of said element, means to substantially completely insulate said last mentioned meansfrom gaseous discharge irom said first mentioned means, and an ionizable gas at a pressure of approximately 200 mm.

, ot mercury surrounding said element, said gas having a breakdown potential along said element below that in the element necessary to raise the element to electron emitting temperature.

3. An electric lamp comprising an envelope, a

. high resistance electron emitting element containing an oxide 0t thealkaline earth metals,

means to support one end of said element, means to support the other end 0! said element, means to substantially completely insulate said last said first mentioned means, and an ionizable gascontaining mercury vapor surrounding said element and having a pressure and breakdown po tential such that the ionization thereof is confined to the region of said element when said element is energized.

4. An electric lamp comprising an envelope, a high resistance electron emitting element containing an oxide of the alkaline earth metals, means to support one end of said element, means to support the other end of said element, means to substantially completely insulate said last mentioned means from gaseous discharge from said first mentioned means, and an ionizable gas containing mercury vapor surrounding said element and having a pressure of substantially 200 mm. of mercury, said gas having a breakdown potential along said element below that potential in the element necessary to raise the same to electron emitting temperature.

5. An electric lamp comprising an envelope, a plurality oi electron emitting elements connected in series, a plurality of low resistance conductors, one connected between every two of said elements, means) to support the free end of the end electron emitting element, means to support the free end of the opposite end electron emitting element, a tube of insulating material surrounding one of said last mentioned means and substantially completely insulating it from the first means, and an ionizable gas containing mercury vapor surrounding said elements and having a pressure of substantially 200 mm. of mercury.

6. An electric lamp comprising an envelope, a plurality of electron emitting elements connected inseries, a low resistance conductor between every two of said elements, means to support the free'end of the end element, means to support the, free end of the element on the other end,

means to substantially completely insulate said SAMUEL RUBEN.

1 substantially 200 mm.