US3250934A

US3250934A - Electric discharge device having heat conserving shields and sleeve

Info

Publication number: US3250934A
Application number: US325672A
Authority: US
Inventors: Carl L Peterson
Original assignee: Sylvania Electric Products Inc
Current assignee: GTE Sylvania Inc
Priority date: 1963-11-22
Filing date: 1963-11-22
Publication date: 1966-05-10
Anticipated expiration: 1983-05-10
Also published as: GB1071103A

Description

y 1966 c. L. PETERSON 3,250,934

ELECTRIC DISCHARGE DEVICE HAVING HEAT CONSERVING SHIELDS AND SLEEVE Filed Nov. 22, 1963 2 Sheets-Sheet 1 CARL L. PETERSON I NVEN TOR.

AT RNEY May 10, 1966 C. L. PETERSON ELECTRIC DISCHARGE DEVICE HAVING HEAT CONSERVING SHIELDS AND SLEEVE Filed NOV. 22, 1963 2 Sheets-Sheet 2 I47 I48 I46 I52 I08 us" -I03 I04 J27 IoI H? -I05 I45 I06 I40 9 CARL I PETERSON INVENTOR.

AT NY United States Patent 3,250,934 ELECTRIC DISCHARGE DEVICE HAVING HEAT CONSERVING SHIELDS AND SLEEVE Carl L. Peterson, Rockport, Mass, assignor to Sylvania Electric Products Inc., a corporation of Delaware Filed Nov. 22, 1963, Ser. No. 325,672 4 Claims. (Cl. 31317) This invention relates to high pressure electric discharge devices and particularly to discharge devices containing mercury, iodine and a metal which modifies the lamps emission color.

High pressure electric discharge devices containing mercury are well known to the art. Such devices have been modified by adding a halide, particularly iodine, to the arc tube fill together with a metal which changes the lamps emission.

Examples of the modifications are given in the copending application of Waymouth et al., S.N. 209,974, filed July 16, 1962 entitled High Pressure Electric Discharge Device; Waymouth et al., S.N. 230,944, filed October 10, 1962, entitled Electric Discharge Device and Butler et al., SN. 239,272, filed November 21, 1962, entitled Electric Discharge Device, each of the several applications being assigned to the same assignee as the instant invention.

The devices of the art containing mercury alone have had serious handicaps because of their emission color. The typical mercury discharge produced light consisting of discrete, separate wavelengths, generally called lines. Almost all of the radiation was contained in the blue region together with a line in the green and a line in the yellow. Hence when conventional mercury lamps illuminated red objects, particularly those reflecting light only in the range of 6000 to 6800 A., the objects appeared black.

Because of the addition of iodine and metals which change the lamps emission color, it'has been found that the temperature at which the arc tube operates has to be raised. Without such elevation in temperature, the chiciency is not high and the emission color can be changed.

I have now discovered a means to elevate the temperature of the arc tube and hence increase the efliciency of the lamp. According to my invention, I form a heatentrapping chamber by surrounding the arc tube with a transparent glass sleeve and supporting the bottom and top of the sleeve with reflective plates. The construction of the plates not only raises the temperature of the arc tube but also prevents breakage of the sleeve.

Accordingly, the primary object of my invention is increasing the efliciency and stabilizing the emission color of metal-halide containing, high pressure electric discharge devices.

A feature of my invention is mounting a cylindrical glass sleeve about the arc tube and supporting the sleeve by reflective plates on tabs extending therefrom.

An advantage of my invention is that the support of the glass sleeve which I obtain increases the stability of the device and reduces breakage.

The many other objects, features and advantages of the instant invention will become manifest to those conversant with the art upon reading the following specification when taken in conjunction with the accompanying drawings wherein preferred embodiments of my device for increasing the efliciency and stabilizing the emission color of mercury-halide-metal containing high pressure electric discharge devices are shown and described by way of illustrative examples.

Of these drawings;

FIGURE 1 is an elevational view, partly in crosssection, of a high pressure electric discharge device showing one type of arc tube with which the device of my invention can be used.

3,250,934 Patented May 10, 1966 FIGURE 2 is an enlarged perspective view taken on line 2-2 of FIGURE 1 of the mounting of the arc tube on the upper reflective shield.

FIGURE 3 is an elevational view, partly in crosssection, of a high pressure electric discharge device showing another type of arc tube with which my invention applicability.

A high pressure discharge device such, as shown in FIGURE '1, comprises an outer vitreous envelope or jacket 2 of generally tubular form having a central bulbous portion 3. The jacket is provided at its lower end with a re-entrant stem 10 having a press through which extend relatively stiff lead-in wires 6 and 7 connected at their outer ends to the electrical contacts of a usual screwtype base 8 and at their inner ends to the arc tube and the harness.

The arc tube 12 is made of quartz and has sealed therein at opposite ends, the

main discharge electrode

13 and 14, which are supported on lead-in wires 4 and 5 respectively. Each main electrode comprises a core portion which may be a prolongation of the lead-in wires 4 and 5 and may be prepared of a suitable refractory metal such as tungsten or molybdenum. The prolongations of the lead-in wires 4 and 5 are surrounded by tungsten wire helixes. A small piece or sliver of thorium metal (not shown) is inserted between the core and the helix to reduce the cathode drop during operation. An auxiliary starting pro-be or electrode 18 is provided at the base end of the arc tube 12 adjacent main electrode 14 and comprises an inwardly projecting end of another lead-in wlre.

Each of the current lead-in wires described above have their ends welded to intermediate foil sections of molybdenum which are hermetically sealed within pinch seal portions of the quartz arc tube. The foil sections are very thin, for example approximately 0.0008" thick, and go into tension without rupturing or scaling off when the quartz cools. Relatively short molybdenum wires 23, 24 and 25 are welded to the outer ends of the foil and serve to convey current to the various electrodes inside the arc tube 12.

Metal foil strip 46 is welded to the outer end of the lead-in wire 23 and a resistor 26 is welded at one end to lead-in wire 24 and at the other end to the arc tube harness. The resistor may have a value of, for example, 40,000 ohms and serves to limit current to auxiliary electrode 18 during normal starting of the lamp. Metal foil strip 46 is welded directly to stiff lead-in wire 7. Metal foil strip 35 is welded at one end to a piece of molybdenum foil sealed in the arc tube 12 which in turn is welded to main electrode 13 and at the other end to the harness. The pinched or flattened end portions of the arc tube 12 form a wide seal using substantially the full diameter of the tube 12 and are made by flattening or compressing the end of the are tube 12 while it is heated. In addition to the halide and the metal which changes the emission color as described before, the arc tube 12 is provided with a filling of an ionizable media such as mercury in suflicient quantity to be completely vaporized when pressure-is developed in the order of /z to several atmospheres during operation of the lamp. In addition, a small quantity of a rare gas such as argon, at a normal pressure of 25 mm. of mercury is introduced to facilitate starting.

The U- shaped wire, internal supporting assembly or are tube harness serves to maintain the position of the arc tube 12 substantially coaxial within the envelope 2. To support the are tube 12 within the envelope 2, the stiff lead-in wire 6 is welded to the base 53 of the harness. Because stilt lead-in wires 6 and 7 are maintained at different electrical potentials, they must be insulated from each other, together with all members electrically associated with each of them. A rod 59 bridges the free ends of the U-shaped support wire 54 and is fixedly attached theretoto impart stability to the structure. The free ends of the U-shaped support wire 54 are also provided with a pair of resilient metal leaf springs 60, frictionally engaging the upper tubular portion of the lamp envelope 2.

Supported upon the legs of the U-shaped harness 54 are a pair of

reflective plates

61 and 62, the purpose of which is to support a glass sleeve 55, entrap heat generated by the arc tube 12 and raise the temperature. Preferably these

plates

61 and 62 are attached to the harness 54 by spot welding a pair of braces 65 to the legs of the frame. Of course, the braces can be eliminated and the plates welded directly to the leg 54 if the sleeve 55 is not too heavy.

The sleeve 55 is resiliently supported upon tabs 66 which extend outwardly from the periphery of the

plates

61 and 62 and are bent inwardly toward the center. The tabs 66 are desirably bent so that a small gap will be left between the

plates

61 and 62 and the ends of sleeve 55 when the latter is mounted. This arrangement provides some ventiliation about the arc tube. In addition, the tab-type mounting provides resiliency and allows the glass sleeve 55 to move slightly if the lamp is shaken thereby avoiding rigidity which could cause damage.

Preferably the sleeve 55 is made of quartz glass which is transmissive to ultraviolet light. Other types which may be used, however, are vanadium loaded glass which will transmit visible and infrared but absorb ultraviolet light. Furthermore, dichroic coatings can be used which absorb infrared radiation but transmit other light.

The are tube 12 also is supported by the reflective plates 62 and 63. With reference to the lower plate 61, the end of the arc tube 12 extends through an aperture in the plate and is laterally supported by mutually opposed flanges 67 (only one of which is shown). The ends of the flange 67 are crimped and usually spot welded together to fit tightly around the press seal. The are tube 12 is supported at the upper end by the plate 62 in a similar manner.

Referring now to FIGURE 2, the perspective view of the assembly is shown in more enlarged detail. As shown, the end of the arc tube 12 extends upwardly through an apertured plate 62, the aperture being formed by 'stamped out sections which are bent to form mutually opposed flanges. The ends of the flanges 68 are crimped together to make the fitting abut tightly against the press seal portion of the arc tube and prevent it from moving.

Upwardly extending as stamped out sections of the plate 62 are braces 65 which are attached to the legs 54 of the harness by spot welding. Downwardly depending from the periphery of the plate 62 are tabs 66 which hold glass sleeve 55 and prevent it from moving while concurrently providing a ventilation port through which the gas in the outer bulbous envelope can circulate.

Referring now to FIGURE 3, a different type of arc tube is shown. In the figure, the arc tube 101 is generally made of quartz although many other types of highmelting, transparent materials such as alumina glass or Vycor may be used. The press seals 103 and 105 are formed in a conventional manner and according to conventional techniques by heating a glass tube to its softening point and then press sealing the sides together upon a series of lead-in wires and molybdenum foil sections which extend through the seal from the outside of the tube to the inside. Attached to the molybdenum foil sections and the inside of the arc tube are the cathodes which are similar to those conventionally used in the art. These cathodes comprise tungsten or

molybdenum core portions

111 and 113 upon which wire helixes 102 and 104 can be mounted.

Such are tubes can have heater coils 115 and 112 disposed upon lead-in wires 119 and- 117 which, extend through the press seals 103 and 105 to external circuitry.

welded directly to the

molybdenum foil sections

106 and 108. The heater coils extend from inside of the seal to a position surrounding the

core portions

113 and 111 for a few turns at which point they are screwed onto the

helixes

102 and 104 so that the ends of the wires of the heater coils are substantially at the same points as the ends of the wire helixes. It is generally found desirable to wrap three or four turns of the heater coil about the

core portions

111 and 113, however they should be spaced and hence, electrically insulated therefrom. It has been found that for 400 watt lamps, a 0.008 to 0.0011 inch wire should be used for the heater coils 115 and 127 although these diameters may be varied between about 0.006 to 0.015 inch depending upon the size of the lamp.

A starting probe 123 can be positioned through the press seal 105 to extend into the interior of the arc tube and facilitate initiation of the arc as is conventional with high pressure electric discharge devices. The probe 123 may be positioned anywhere in the arc tube so long as the ends are reasonably close to the respective cathodes. Hence they may even extend through the side wall of the arc tube 101 rather than through the press seal 105. A position in the side wall is frequently desirable because electrolysis between the bases of the probes and the cathodes may be markedly reduced, it being almost impossible for electrolytic action to take place at such disto the power supply and heater coil 115 is connected to the other side of the power supply through lead-in wire 136. Frequently a circuit breaker (not shown) is disposed between probe lead-in line 137 and cathode leadin line 138 to short out the probe circuit and prevent electrolysis when an arc is formed in the arc tube 101.

A further description of the circuit is given in the copending application of John F. Waymouth entitled Electric Discharge Device, Serial No. 302,656, filed August 8, 1963 and assigned to the same assignee as the instant application.

Mounted upon the harness legs are upper and lower

reflective plate

139 and 140. Noting upper plate 139, a brace 141 is spot welded to leg 133 and is disposed with a slip-fit, collar-type insulator 142 about harness leg 143. Lower plate is spot welded through brace 144 to harness leg 143 and is disposed with a slip-fit, collar type insulation 145 upon harness leg 133. The

insulators

143 and 145 may be prepared of any suitable insulating material such as a ceramic.

Insulation of the plates from the legs of the harness is necessary because each leg carries opposite sidesof the power line. Additionally, it is necessary to insulate the legs from each other at the top of the frame by providing an insulator tube 148 which is disposed upon inwardly extending

rods

146 and 147, the inward ends of the rods being sufliciently spaced from each other to prevent a short circuit.

The disposition of the arc tube within the aperture formed by crimped flanges 149 and 150 is similar to that shown and described with reference to FIGURES 1 and 2. Furthermore the support of the glass sleeve 153 upon the inwardly extending tabs 152 is similar to that described previously.

It is apparent that modifications and changes can be made within the spirit and scope of the instant invention but it is my intention, however, to be limited only by the scope of the appended claims.

As my invention I claim:

1. A high pressure electric discharge device comprising: an arc tube containing a halide and an are forming metal disposed within an outer bulbous envelope, said are tube having press seals at either end thereof; an arc tube harness disposed within said envelope; a pair of plates disposed upon said harness; a glass sleeve disposed between said plates and about said are tube; means forming an aperture in each of said plates, said press-seals extending through said aperture; a series of tabs disposed upon each of said plates projecting inwardly into the interior of said sleeve, said sleeve resting upon said tabs and being supported thereby to form a heat entrapping chamber about said arc tube and between said plates.

2. The device according to claim 1 wherein the ends of said sleeve are spaced from said plates.

3. A high pressure electric discharge device comprising: an arc tube containing a halide and an are forming metal disposed within an outer bulbous envelope, said are tube having press-seals at either end thereof; an arc tube harness disposed wihin said envelope; a pair of plates disposed upon said harness; a pair of flanges stamped from each of said plates and forming an aperture therein; a glass sleeve disposed between said plates and about said arc tube; the press seals of said are tube ex tending through said plates and being secured by said flanges; a series of tabs disposed upon each of said plates and projecting inwardly into the interior of said sleeve, said sleeve resting upon said tabs and being supported thereby to form a heat entrapping chamber about said are tube and between said plates.

4. The device according to claim 3 wherein the ends of said sleeve are spaced from said plates.

References Cited by the Examiner UNITED STATES PATENTS 2,841,733 7/1958 Hodge '313220 X 2,972,693 2/ 1961 Rosenberg 313-17 X 3,085,171 4/1963 Srnialek 313-25 FOREIGN PATENTS 737,913 10/ 1955 Great Britain.

20 GEORGE N. WESTBY, Primary Examiner.

S. SCHLOSSER, Assistant Examiner.

Claims

1. A HIGH PRESSURE ELECTRIC DISCHARGE DEVICE COMPRISING: AN ARC TUBE CONTAINING A HALIDE AND AN ARC FORMING METAL DISPOSED WITHIN AN OUTER BULBOUS ENVELOPE, SAID ARC TUBE HAVING PRESS SEALS AT EITHER END THEREOF; AN ARC TUBE HARNESS DISPOSED WITHIN SAID ENVELOPE; A PAIR OF PLATES DISPOSED UPON SAID HARDNESS; A GLASS SLEEVE DISPOSED BETWEEN SAID PLATES AND ABOUT SAID ARC TUBE; MEANS FORMING AN APERTURE IN EACH OF SAID PLATES, SAID PRESS-SEALS EXTENDING THROUGH SAID APERTURE; A SERIES OF TABS DISPOSED UPON EACH OF SAID PLATES PROJECTING INWARDLY INTO THE INTERIOR OF SAID SLEEVE, SAID SLEEVE RESTING UPON SAID TABS AND BEING SUPPORTED THEREBY TO FORM A HEAT ENTRAPPING CHAMBER ABOUT SAID ARC TUBE AND BETWEEN SAID PLATES.