US2042244A - Gaseous electric discharge lamp - Google Patents

Description

May 26, 1936. w. J. WINNINGHOFF GASEOUS ELECTRIC DISCHARGE LAMP Filed Feb. 19, 1932 3 Sheets-Sheet l May 26, 1936. w. J. WINNINGHOFF 2,042,244

GASEOUS ELECTRIC DISCHARGE LAMP Filed Feb. 19, 1932 3 Sheets-Sheet 2 INVENTO TTORNEY y 6- w. J. WINNINGHOFF GASEOUS ELECTRIC DISCHARGE LAMP Filed Feb. 19, 1932 3 Sheets-Sheet 3 INVENTOR Patented May 26, 1936 UNITED (STATES PATENT OFFICE signor to General Electric Vapor Lamp Company, Hoboken, N. 1., a corporation of New Jersey Application February 19, 1932, Serial No. 594,115

ZOIaimS.

The present invention relates to electric gaseous discharge devices, and more particularly to mercury vapor lamps and the like.

The invention consists in the new and novel 6 structure and combination of elements, as hereinafter set forth and claimed.

A particular object of the invention is to provide a vapor arc lamp which will have improved operating characteristics, and a long useful life. Another object of the invention is to provide a vapor arc lamp which may be easily started into operation. Another object is to provide a vapor arc lamp in which the arc tube is maintained in v a fixed position. Another object of the invention is to provide a vapor arc lamp in which the arc tube is effectively protected by the reflector. A further object of theinvention is to provide a vapor arc lamp having no live electrical contacts I exposed. Still another object of the invention is to provide a vapor arc lamp all the elements of which operate at a relatively low temperature.

Still other objects and advantages of the invention will appear from the following detailed specification, or from an inspection of the accom: panying drawings.

In the operation of vapor arc lamps, such as the well known mercury arc lamps of the alternating current type, failures have occasionally been'caused by the short circuiting of the anodes.

I have found that thisshort circuiting is caused by a film formed by particles sputtered from the anodes during operation, and particularly during that part of each cycle when the anodes are inactive. I have furthermore found that this sputtering may beivery effectively reduced by constricting the entrances to the anode chambers, and by making this constriction relatively long, whereby the diffusion of positive ions to the anodes is appreciably reduced. By a novel ar- 40 rangement of a bead about theanode inlead I have also found it possible to provide a long surface path between the anodes, a portion of which is substantially shielded from sputtered particles.

As a result of these improvements I find that my 45 new lamp is virtually immune to failures due to short circuiting of the anode, despite the relative close spacing of the anodes. I have also found that the reduction or absence of the sputtered film greatly facilitates the initiation of the are.

50 The novel arrangement of the anode chambers, substantiallyon the same level as the arc tube, is of special advantage, since it permits these chambers to be placed within theaefiector which 6 is commonly used, whereby these chambers are eifectively shielded from the breakage so fre-' quently encountered in lamps having 'the upwardly extending horns heretofore in use. Failure of these devices has also occasionally occurred due to the rotation of the arc tube, as the result of excessive vibration or the like, until-the inlead 5 to the mercury cathode became exposed, whereupon the arc would transfer to said inlead, with the resulting destruction of the'arc tube at the cathode seal. I have discovered that this difilculty may be easfly overcome by interlocking the 10 arc tube with the reflector, so as to positively preclude rotation of the arc tube in its clamps. This novel construction also permits the use of a much smaller quantity of mercury for the cathode than has been heretofore practicable, with a I corresponding decrease in the cost of the lamp. The smaller quantity of mercury also decreases the hazard heretofore encountered as a result of mercury hammer during the handling of the device. By a novel system of connections I have also provided insulation about all exposed electrical parts, while by housingthe ballast resistances within a tight metal container the maximum operating temperature of the exposed parts has been greatly reduced, both of these factors affording further safety in the operation of my new lamp. The insulating connections employed at the anodes also cut down the heat radiation from the anode chambers, with a resulting increase in the temperature of these chambers which prevents the condensation of mercury therein.

For the purpose of illustrating my invention I have shown a preferred embodiment thereof in the accompanying drawings, in which Fig. 1 is an elevational view, in part section, of a mercury vapor arc lamp of the well known Cooper Hewitt type,

Fig. 2 is a schematic diagram of the same lamp, showing the electrical connections and auxiliary apparatus associated with the arc tube,

Fig. 3 is a plan view, in part section, of the arc be,

Fig. 4 is an elevational view, in part section, of the same are tube.

Fig. 5 is an end view, in part section, of the lamp of Fig. 1, showing the interlocking of the arc tube with the reflector,

Fig. 6 is an elevational view, in part section, of the novel resistance unit employed in my new lamp, and v Fig. Tis a sectional view of one of the insulated terminals used on the wires connecting with said are tube.

Asshowninthesedrawinss thelampconsistsof three main units: an arc tube I, a reflector 2, and an auxiliary unit 3. Said arc tube I, which is of any suitable vitreous material, has a spherical bulb 4 at one end thereof, in the bottom of which there is formed a small well 5. Directly over said well 5 there is formed an outwardly extending cup through which is sealed an inlead 6, a screw cap 1 which is fltted over said cup being connected to said inlead. Said inlead extends downwardly to a point within the well 5, being beaded throughout its length except for a short portion thereof near the bottom of said well. A pool of mercury 8, comprising the cathode, fills said well i and extends for some distance thereabout within said bulb 4. That part of the inner surface of said bulb which is in contact with the mercury meniscus is preferably coated with carborundum or other granular substance 9 in order to make said mercury meniscus irregular and thereby facilitate starting. This carborundum is preferably held in place by fritting itto the bulb, a convenient method therefor being disclosed in my copending application, Serial No. 511,409, filed January 26, 1931. A similar outwardly extending cup III is formed in the wall of said bulb opposite the arc tube I, through which extends a short inlead I I. Said inlead is used only during the so-called "treating of the lamp during the manufacture thereof, when it is sometimes convenient to operate the tube in a vertical position, hence when completed this inlead is cut oil as close as possible on the outside of said cup III. A conducting sheath I2, which is conveniently formed of overflicker of the arc due to movement of the hot spo on the mercury 3.

At the opposite end of the arc tube I there are a pair of spherical anode chambers l4 which are connected to said arc tube through the relatively constricted tubes IS. The axes of said tubes l5 are each at an angle, of the order of 22 degrees, with the axis of the arc tube I, and lie in'the plane determined by the axis of said are tube and a horizontal line which is perpendicular thereto. An inlead I6 is sealed into each of said anode chambers I4 through a reentrant seal at a point opposite the tube I5, an anode I'I being attached to the inner end of each of said inleads. About each of said inleads is a head It which extends from the seal to a point near said anode,

an appreciable portion, of the order of at least one fourth of an inch, thereof near said anode tion in the cylindrical reflector 2 by means of suitable clamps 20, with the screw cap I extending upwardly through an opening in said reflector. Mounted on said reflector is the auxiliary unit 3. As shown in Fig. 2 this auxiliary unit comprises an autotransformer 2|, two resistance units 22, an

inductance 23, a rectifier 24, a condenser 25, and

a shifter 28. Suitable taps on said autotransformer 2| are connected to the line, while the ends thereof are connected through the resistances 22 to a pair of sockets 21 which are screwed 5 onto the caps I9, the leads between said resistances and said sockets passing through a suitable conduit on said reflector, and thence through, an opening in said reflector which is adjacent to the anode end of the are tube I. The midpoint of 10 said autotransformer is connected through the inductance 23 to another socket 21 which is screwed onto the screw cap I, said socket loosely fitting in the aforesaid hole in said reflector through which said cap extends, whereby said socket cooperates 15 with said reflector to prevent rotation of the arc tube in said reflector. From a point between said inductance 23 and said socket 21 a connection is made through the shifter 26 to the midpoint of the full-wave rectifier 24, the other terminals of said rectifler being connected to low voltage taps on either side of the midpoint of said autotransformer 2I From a point between said shifter 26 and the rectifier 24 a connection is made through a condenser 25 to another socket 21 which is screwed onto the cap I3.

As shown in Fig. 6, the resistances 22 comprise an annular vitreous member 30 having a helical groove in the outer wall thereof, within which is placed a helically wound iron resistor 3 I, the ends of said resistor being connected to the tip and sleeve of a conventional screw base. A metal cover 32 is placed over the resistor 3|, the edge l of said cover making a friction flt with a flange on the annular member 30, suitable ears on said 35 cover being used to hold it in place thereon. This construction affords both a large heat radiating surface, with resulting lower operative temperature, and a means for protecting the associated apparatus from damage or failure as a result of a broken resistor 3|, which otherwise might uncoil and make undesirable electrical connections.

The sockets 21 are shown in detail in Fig. 7. These sockets comprise a moulded housing 33 of bakelite or the like, within which there is aflixed 45 a threaded sleeve 34. The insulated lead wire 35 extends through a tubular part of the housing 33, the end thereof being stripped and soldered to a contact making member 36 which fits within the end of the sleeve :4. A flanged sleeve :1 is crimped down onto said lead just outside of the housing 33, whereby the various parts of the socket are locked in place, while a similar flanged sleeve 33, reversed, extends into the tubular part of said housing, and serves as a bushing to permit free rotation of said housing 33 and sleeve 34 on said lead 33. These sockets are easily attached, and'iully insulate all live parts of the arc tube I. Even more important, however, is on the fact that the sockets 21 which are connected to the caps I! also serve to materially decrease the escape of heat from the anode chambers I 4, with the result that these chambers operate at a temperature which is sumcient to prevent the condensation of mercury therein, thus permitting the use of the highly. desirable anode arrangement illustrated.

In the operation of this device, the arc is initiated by producing a voltage surge on the starting band I2 according to the method disclosed in Patent 2,001,517, granted May 14, 1935 to Lemy J. Buttolph, this being a most effective means for producing the arc. The condenser 25, which is used to insulate the starting band I2, offers little impedance to this surge but permits the passage of virtually no energy at the usual frequency of 60 cycles or less. Due to the interlocking of the arc tube 1 with the reflector 2, by means of the cathode inlead assembly, there is no danger of the tube rotating in its supports 20, hence I find it possible to reduce the mercury employed to substantially a third of that which has heretofore been considered necessary for safety. This novel arrangement of the cathode inlead is also desirable, since it avoids virtually all danger of mechanical breakage, during handling, cleaning, and the like. At the opposite end of the tube the anode arrangement is extremely conductive to long life of the tube. Due to the constricted tubes l5, which I find it advisable to make say three-eighths to one-half inch long, and .of say one-half inch diameter, where the main arc tube is fifty inches long and an inch in diameter, there is very little material sputtered from the anodes at any time. Hence the formation of a conducting film on the wall of said anode chambers is almost entirely eliminated. By using a reentrant seal, as shown, for the anode leads IS the surface path which must be covered by this film is materially increased, with a corresponding reduction in the possibility of short circuit due to this film. Even more effective for this purpose is the arrangement of the bead l8, since by making the spacing between said lead and the flare on said bead small virtually no material can be sputtered onto the inside of the flare, nor can the discharge attach itself to the inlead therein. As a result my new lamp is virtually immune to failure by anode short circuiting. The hazard of breaking these anodes is also materially reduced by their new location with respect to the arc tube, since they are now effectively shielded by the reflector 2. The aforesaid reduction in the sputtered film also facilitates the starting of the arc. This is due to the fact that such a film tends to hold globules of condensed mercury, and ii the film is in contact with either anode these globules can serve as a cathode, drawing the arc thereto instead of to the main cathode. the main arc can not be initiated until these mercury globules have been evaporated. Due to the elimination of this condition the probability of the initiation of the main are upon the application of the first voltage surge is vastly increased.

While I have described myinvention by reference to a specific embodiment thereof, it is to be understood that it is not limited thereto, but that various changes; substitutions or omissions.

In such a case within the scope of the appended claims, may be made therein without departing from the spirit oi. my invention.

I claim as my invention:-

1. A gaseous discharge lamp having an elon- 5 gated luminous arc tube having two bulbous anode chambers connected to one end thereof through relatively constricted tubular throats, a cup shaped anode in each of said chambers facing said throat, said throats each having a diameter and a length equal to the diameter of said anodes, the axes of said throats being at an angle to the axis of said tube in the plane determined by said axis and a horizontal line which is perpendicular thereto, a cathode bulb at the opposite end of said tube having a well extending from the bottom thereof, a pool of mercury in said cathode bulb, an inlead sealed through the top of said cathode bulb and extending downwardly into said well, said inlead being enclosed within an insulating sheath to a point below the level of said mercury, and a conducting sheath on the outside of said cathode bulb in electrostatic relation to said pool.

2. A mercury lamp comprising a trough reflector, a. straight luminous arc tube, means to support said arc tube within the curvature of said reflector, said are tube having two bulbous anode chambers connected to one end thereof through relatively constricted tubular throats, a cup shaped anode in each of said chambersfacing said throat, said throats each having a diameter and a length equal to* the diameter of said anodes, the axes of said throats being at an angle to the axis of said tube in the plane determined by said axis and a horizontal line which is perpendicular thereto, a cathode bulb at the opposite end of said tube having a well extending from the bottom thereof, a pool-of mercury within said cathode bulb, an inlead sealed through the top of said bulb and extending downwardly into said well, said inlead being enclosed within an insulating sheath to a point below the level of said mercury, a conducting sheath on the outside of said bulb in electrostatic relation t said pool, a. terminal on the top of said cathode bulb connected to said inlead, and a connector attached to said terminal which passes through an opening in said reflector, said connector having an insulating sheath which fits said opening, whereby said tube cannot be rotated within said reflector to move said inlead out of contact with v said pool.

WILFORD J. WINNINGHOFF.

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