US910736A - Electric lamp and method of making the same. - Google Patents

Description

APPLICATION FILED NOV. 17, 1902.

Patented Jan. 26, 1909.

2 SHEETSSHEET 1.

Fig.4.

Ihventor. Ch arles P. Steinmetz.

Witnesses.

G. P. STEINMETZ. ELECTRIC LAMP AND METHOD OF MAKING THE SAME. APPLIOATION FILED NOV. 17, 1902.

910,736. Patented Jan. 26, 1909.

Z SHEETS-SHEET 2 Witnesses. Inventor.

Charles P. Steinmetz.

' To all whom it may concern:

-' terminals crane lam them in suflicient quantities.

UNITED STATES PATENT OFFICE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGN OR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK. ELECTRIC LAMP AND lIETHOD OF MAKING- TEIE SAME.

Patentedil'an. 2c, 1909.

Application filed November 17, 1902. Serial No. 131,660.

Be it known that I, CHARLES P. STEIN- METZ, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Electric Lam s and Methods of Making the Same, of whic the following is a specification.

I have found that the 0 eration of electric lamps of that type of w ich the so-called mercury arc lamp is the best known exampie is much improved if they are run at igher tem eratures than those which have' heretofore een practiced. If mercury be employed as the volatile electrode the color of the light improves as the temperature of the lamp increases. Moreover, if the lam is run at a higher temperature other substances, such as lithium, potassium, magnesium, sodium, and various combinations of these metals may be added to the mercur by which the quality of the light can be st' 1 further improved. In place of using inercury or substances containing mercury, other materials having a comparatively low boiling point may be em loyed to form the va or1z1ng electrode of tlie lamp. If these su stances are employed in the vapor arc lamp running at the temperatures which ave heretofore been commonly employed, the advantages due to their lightgiving power are only partially obtained as the tem perature is not high enough to volatilize Another advanta e, which res ts from the employment of high temperatures in lamps of this character, is due to the fact that with such temeratures, the drop in voltage between the amp terminals necessary in order that the lamp may be used on ordinary circuits can be obtained with a tube which is considerably shorter than those heretofore employed. The limit to the temperature at whlch it has heretofore been possible to run these lamps has been given by the heat-resisting ower of the lass tube formin the Walls 0 the exhausted chamber in whic the are placed. I have found that ifthe wa or walls of the exhausted chamber, or at least of that portion of it surrounding the light iving are, are made out of fused quartz, t e temperature at which the lamp can be 0 erated is greatly increased, and that thereby the above noted advantages due to such an increase in temerature can be obtained. Tubes formed of used quartz will stand heatin to a much hi her temperature without so 'tening than wil glass tubes, moreover rapid and extreme changes of temperature do not have the tendency to' crack the tubes which exists with glass tubes under such conditions.

In the accom anying drawings I have illustrated severa embodiments of my invention.

In the drawings Figure l is a sectional elevation showing one construction of lamp; Fig. 2 is a partial sectional elevation showing a slight'l modified construction; Fig. 3 is a sectiona elevation showing a somewhat different construction of lamp; Fig. 4 is a diagram showing the relative proportion of the different materials composing the lamp tube shown in Fig. 3; Fig. 5 is a sectional elevation showing a paratus employed in the manufacture of amp tube shown in Fig.3; and- Fig. 6 is a plan view showing the same ap aratus.

n the construction shown in Fig. 1, a light-transmitting tube 1 made out of fused quartz forms the inclosing chamber of my lamp. A solid terminal 2 is placed at the upper end of the tube. At the lower end of the tube a mass of materialB, such as mercury, or a mercury amalgam containing various substances which va orize at the temperature employed, or the ikc, is placed and forms the other main electrode. The tube 1 is provided at its lower end with an off-shoot 4 and in this oil-shoot 4 is placed another mass 5, similar to the mass 3, forming an auxiliary or starting electrode. The lower end of the tube 1 and the oii-shoot 4 are shaped to form comparatively small tapered necks 6, and on the outside of these tapered necks are fitted caps of metal 7. The outer surface of the necks 6 and the interior surface of the caps 7 may be ground to form air-tight joints. The metal caps are in electrical contact with the mercury and have suitable current-carrying leads connected to them. The metal out of which I form the caps 7 is a mixture of nickel with iron or steel, the amount of nickel in the composition being about 35% to 37 I employ; this mixture as its thermal coefiicient of expansion is approximately equal to the thermal coefiicient of expansion of the quartz, which is very small, being much less than that of glass.

llO

Iemploy the joint described owing to the difliculty of making a sealed joint such as is employed with glass tubes due to the efiect the caps 7. The tube is ground interiorlyat 10 and the plug 9 is inserted to make a tight fit. Above the portion 10 the end of the tube may be flared to form a chamber 11 in which a quantity of mercury is placed to sealthe joint. not be ,mte a1 with the tapered plug 9. Preferabl t e terminal 2 and the plug 9 are connecte by a portion 12 considerably smaller in diameter than the tcrminal 2 in order that the heat conducted from the terminal 2 to the plug 9 ma be diminished. The tube 1 is exhausted in t 0 same manner as has heretofore been em loyed in exhausting glass tubes. At 13 I ave indicated the fused oif exhaust tube..

In Fig. 2 I have shown a slightly difi'erent method of closing the upper end of the tube. In this construction a cap 9, similar to the cap 7 shown-at the lower end of Fig. 1, is employed at the upper end of the tube. The solid-terminal 2 is connected thereto by a slender portion 12 as in Fig. 1. The upper end of the quartz tube may be'shaped to receive a mercur seal, desired.

Instead of orming the tube entirely of quartz and forming metallic end connections as above described, the tube may be made with its body portion of fused quartz and its end portions of some different substance into which metallic leading-in wires can befused in the ordinary manner heretofore practiced in making tubes for lamps of this character. In Fig. 3 I have shown a lamp of this character similar in its eneral arrangement to the lamp shown in ig. 1, but in which the portion of the lamp tube 1 be-. tween the lines A A and B B 1s formed of fused quartz, while the terminal portions beyond the lines A A and B B respectively are formed of a material containing silica,-

united with various other substances; for instance, otassium and calcium hydroxid may be a ded to the fused uartz to make the terminal ortions of t e lamp. The potassium an calcium hydroxid or other substances, which are united with the silica to form the terminal portions of-the tube,

should be added in such manner that the roportion of these substances should vary from zero at the lines A A and B B respecrovided The terminal 2 may or may-- tivelyto an amount sufiicient to form a glass into which a platinum wire can readily be sealed, as shown, and having practically the same thermal coefiicient of expansion as platinum at the end.

In Fi 4 I have shown a diagram illustrating t e proportion of the materials in the com osition of the tube 1. In this diagram the e D D is equal to the length of the tube 1 and the amount of quartz which is found in the tube at any point along its length is Ernoportional to the distance betweenthe e O B A C and the line D D at the corresponding point. -The amount of other materials employed to form the terminal portions of the tube are indicated by the distance between corresponding points onthe lineCBAC andon thelineEBAE.

It will of course be understood that the quartz and other materials are intimately mixed and are not separated by any distinct line of cleavage as might appear from the diagram. With a tube as thus constructed, the mechanical resiliency of the tube is sufficient to take up the diiference in the.

thermal ergiansion of the tube at the lines A A and B reslpectively and thepoints where the termina wires are se led in.

In forming the lam tubes above described, the following metho may be followed: A refractory conductor such as carbon may be embedded in a mass of quartz granules or silica in other finely divided states. On the passage of a heavy electric current through the conductor, heat is produced sufiicient to fuse the quartz in the vicinity of the conductor, whereupon when the conductoris cooled :a shell of fused quartz is formed surrrounding the conductor. In Figs. 5 and 6 I have illustrated an arrangement by which such tubes may be formed. In these dra s the car hon-heating conductor 14 has su stantially the shape which it is desired to give the inside of the tube. The conductor 14 is connected at its ends to heavy metallic conductors 14 which {are mounted in the wall 15 of the furnace chamber. Filling the lower part of the chamber 15 and surroun 14 is a mass of the material w 'ch it is desired to fuse in order to form a tube. At 16 I have indicated the appearance of such a tube after forming.

- When the tube is formed entirely of fused quartz as in Fig. 1 it will of course be understood that the material 17 surrounding the conductor or core 14 is all silica, but when it is desired to form a tube like that in Fig. 3 the material surrounding different ortions of the core will be different. Only t at ortion of the heating chamber between the es A A and B B, which correspond in position with reference to the tube to'the lines A A and B B of Fig. 3, will be filled with uartz alone. Portions between the lines A A, B and the adjacent ends of the casing will be filled with the conductor,

a mixture containing other materials: That is, with the tube above described, the uartz will be mixed with potassium and ca cium hydroxid and the mass of otassium and calcium hy droxid will be gra uated in the space between the lines A A and B B and the adjacent ends of the casing as indicated in Fig. 4

The rough tube-blank obtained in the heating chamber may have the carbon core burned out and be worked into a finished form by heating in the electric are or other source of great heat.

The operation of the lamp is as follows: At starting, the solid terminal 2 and the vaporizing terminal 5 are connected to one side of the supply circuit, while the main vaporizing terminal is connected to the other side of the line. If, now, the tube be agitated slightly so as to cause the metal forming the terminal 3 to contact with metal forming the terminal 5, an initial vaporization takes place and the vapor thus formed enables the current to pass from the terminal 3 to the terminal 2. After starting, the auxiliary terminal may be cut off if desired. The terminal 2 may have an extension 2 preferably formed of a carbon filament depending from it to a point slightly above the surface of the mercury 3 to assist in starting the are if desired.

If the substance employed to form a vaporizing compound is not fluid at ordinary temperatures, other means for starting the lamp may be employed, as for example those shown in British Patent #5545 of 1903.

While I have illustrated and described the best form of my invention which is now known to me, I do not intend to be limited to the details of construction shown and described as I consider my invention in its broader aspects to be inde endent of such features of construction an to consist in an inclosing chamber for electric lamps made out of fused quartz.

In a divisional a plication, Serial No. 455,110, filed Se tem er 28, 1908, claims are made on an enve op having a body portion of fused quartz and an end portion of a different material. f

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In a vapor electric device, an inclosing chamber formed out of fused quartz and provided with means for conducting current thereinto.

2. In a vapor electric device, an inclosing chamber formed out of fused quartz, and connections therefor formed out of a composition of nickel and steel.

3. In a vapor electric device, an inclosing chamber formed out of fused quartz, and connections therefor formed out of composi tions of nickel and steel or iron, the nickel forming about 37% of the composition.

4. In a vapor electric device, an inclosing chamber having the portion subjected to the heating action of the vapor are formed out of fused quartz.

5. In a vapor electric device, an exhausted chamber the light-transmitting walls of which are made of fused quartz, said chamber having means for conducting currenttheremto.

In witness whereof, I have hereunto set my hand this 15th day of November, 1902.

CHARLES P. STEINMETZ.

Witnesses:

BENJAMIN B. HULLf HELEN ORFORD.

Images