JPS59139543A - High intensity arc discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the radial distribution of metal ion species in a high-pressure metal vapor arc discharge lamp, particularly in an arc discharge tube.
related to things.

High-intensity arc discharge lamps are a type of discharge lamp in which the emitted light power is derived from a plasma arc discharge within an arc tube. One such discharge lamp is a high pressure sodium vapor lamp. This invention is most closely related to this type of high-intensity discharge lamp. Therefore, this type of discharge lamp will be explained in more detail later. However, another type of high intensity discharge lamp currently in common use is the metal halide discharge lamp. In this discharge lamp, the arc discharge tube contains a metal halide, such as sodium iodide, which evaporates and dissociates during operation of the discharge lamp. It can therefore be seen from the above that in the field of discharge lamps both metal vapor discharge lamps and metal halide arc discharge lamps are known. However, the discharge lamp of the present invention is best referred to as a metal and metal halide (metal/metal halide) discharge lamp. From the following description, it is clear that this metal and metal halide discharge lamp is superior to the previously announced high-intensity discharge lamps. It will be appreciated that the discharge lamp of the present invention has unique characteristics not found in arc discharge lamps.Furthermore, it will be appreciated that the discharge lamp of the present invention controls the radial distribution of atoms of the metal species that evaporates.

Regarding the high-pressure sodium vapor couple, it has been found that the self-absorption properties of the cooler helium atoms selectively distributed near the cooler wall of the arc tube act to limit the efficiency of the discharge lamp. Ta. In particular, the sodium D-ray radiation generated within the hot central plasma region of the arc tube is likely to be absorbed by sodium atoms present near the arc tube wall.

This phenomenon is well known in the field of discharge lamps, and solutions to this problem have also been attempted in experiments by several people.

For example, Weymouth and Weiner's article ``High-pressure sodium lamps'' in The Journal of the Illuminating Engineering Society, Vol. 10, pp. 237-244 (July 1981 issue) In ``Analysis of Factors Affecting the Efficiency of Arc Tubes'', the authors show that the density of aluminum near the walls of the arc tube can be reduced by keeping the walls at high temperatures by using wall materials with low infrared emissivity. is proposed. Pending U.S. Patent Application No. 298,838, filed September 3, 1981, discloses an infrared reflective coating on the inner surface of the outer jacket to provide a cooler temperature than in the hot central plasma discharge region. It has been described that the wall temperature is maintained at a high temperature to at least partially reduce the effects of reabsorption of radiation by the cooler metal atoms which tend to accumulate preferentially near the walls of the arc tube. The authors of this experiment also took into account the influence of the diameter of the arc tube on the efficiency of the discharge lamp, and in their study they also took into account the self-absorption of radiation by the sodium atoms. However, no means other than controlling the temperature of the arc tube wall has been proposed to control this absorption phenomenon.

In a preferred embodiment of the invention, a high intensity arc discharge lamp has an outer transparent envelope, a transparent arc discharge tube having electrodes at opposite ends of the arc tube, and means for making electrical connections to the electrodes. More importantly, the arc discharge pair of the present invention includes a volatile discharge medium disposed within the arc tube, which discharge medium contains mercury and non-mercury in amounts as explained below. The active starting gas includes one or more volatile metal species and halides (other than fluoride) of the metal species disposed within the arc tube.

In a particularly preferred embodiment of the invention, the metal species consists of sodium and the halide is iodide. During operation, almost all of the thorium iodide in the center of the plasma arc dissociates, but the thorium iodide on the arc tube wall dissociates! ~Thulium does not dissociate at all. The metal halide species in the vicinity of the arc tube wall are generated in the center of the discharge tube and do not selectively absorb radiation, so there is no noticeable reduction in the efficiency of the discharge lamp.

Furthermore, by controlling the ratio of the partial pressure of 1-lithium iodide to the partial pressure of 1-lithium iodide, the radial distribution of sodium atoms can actually be controlled. In a preferred embodiment of the invention, means are provided to increase the temperature of the arc discharge tube storage section above normal, since higher temperatures are generally required for metal halide vaporization.

Accordingly, another embodiment of the present invention provides for a radial increase in the evaporated metal species within the arc tube of a high intensity discharge pair by including in the arc tube a selected amount of a halide other than the fluoride of the metal species. It will also be understood that the problem lies in the method of controlling the distribution of In particular, fluoride has a strong tendency to corrode and corrode the materials of the arc discharge tube and electrodes, so it is typically not used in discharge lamp devices.

It is therefore an object of this invention to provide a high intensity arc discharge lamp with improved efficiency.

It is an object of this invention to provide a means for controlling the radial distribution of one or more vaporized metal species within an arc discharge tube.

Another object of the invention is to reduce the radial self-absorption effects that occur in high-intensity discharge lamps.

Finally, it is an object of the invention to provide a new type of high-intensity discharge pair, referred to herein as a metal and metal halide discharge lamp, ie a metal/metal halide discharge lamp.

Although the gist of the invention is specifically and clearly described in the claims, the structure, operation, and other objects and advantages of the invention will be best understood from the following description of the drawings.

FIG. 1 depicts a typical high pressure sodium arc lamp, or more generally, a typical high pressure metal vapor couple. The configuration shown in FIG. 1 can also be used in this invention, which generally aims at specific properties of the gaseous discharge medium. In particular, FIG. 1 shows a high intensity arc discharge lamp having an outer transparent envelope 11. As shown in FIG. Preferably, this outer jacket is constructed from a material such as heat resistant glass or quartz. The illustrated discharge lamp also has a translucent arc discharge tube 10 with electrodes disposed inside it at both ends. Arc discharge tube 10 is typically cylindrical and must be resistant to erosion of the materials used in the gaseous discharge medium contained within the arc tube. In particular, arc discharge tube 10 is preferably constructed from a refractory ceramic material such as alumina, and more particularly, sintered polycrystalline alumina. This material has proven to be very resistant to attack by metal species such as sodium. Arc discharge tubes typically have an inner diameter of about 4 mm to about 18 mm. However, about 8 to about 1
A diameter of 0 mm is a more preferred range for the discharge lamp and method of this invention. Finally, referring to arc tube 10, it should be noted that it could actually be constructed from a crystalline material such as Xapphi V. However, the use of this material is generally prohibitively expensive, except in applications where its high cost is offset by the desired benefits obtained by using this material. The volume between arc tube 10 and outer jacket 11 is typically evacuated to prevent heat loss to the arc tube that would cause loss of efficiency.

Although the outer shell 11 and the arc tube 10 constitute the main mechanical structure of the discharge lamp of the invention, other structures are housed therein for electrical connections and support to the arc tube. In particular, the support wire conductor 14 becomes part of the means for connecting the electrodes of the arc tube to external connections via conventional Edison metal 20. Conductive wire support 15 also typically electrically connects to one of the two external metal contacts of Edison gold 20. A conductive, wire A7 support 15 extends upwardly into the vacuum region of the discharge lamp and is welded to a hexagonal brace washer 17 or ring 13 arranged around a recess 12 provided at the end of the outer envelope 11. It is preferable to do so. Furthermore,
Due to the effects of thermal expansion that occurs during operation of the discharge lamp, a separate support 2
7 has an expansion loop 22. Support and conductive wire 2
7 is preferably spot welded to the ring 13 and the lateral support wires 21. The lateral support wires 21 are preferably spot welded to the arc tube termination 24, which also serves as an amalgam or halide reservoir. Similarly, at the base end of the discharge lamp shown in FIG. as well as supplying current to the electrodes therein. Thus, the current path through the gaseous discharge medium typically includes the conductive support wire 14, the lower lateral support 16, and the lower arc tube. Termination part 24, lower electrode of arc tube 10, cassette discharge medium in arc tube 10, upper electrode in arc tube 10, upper arc tube termination part 24, lateral support wire r21, vertical support 2
7 (including the thermal expansion loop 22), the support ring 13 and finally the support wire conductor 15 in this order. The conductive wires 14,15 are connected separately to either the external connection 17 of the metal screw base or the central external contact 19. External contact 17
．． 19 are separated by an insulating material 18. Thus, a means is provided for making electrical connections to the electrodes within arc tube 10. Furthermore, a typical discharge lamp as shown in Fig.
It also preferably includes a coating 23 of getter material disposed on the inner surface of outer jacket 11 to help maintain a vacuum in the volume within arc tube 10 and outer jacket 11.

What has been said above regarding the discharge lamp shown in Figure 1 applies to ordinary high-pressure metal vapor lamps such as high-pressure sodium vapor lamps.
C. This is typical. It is generally these types of discharge lamps that this invention is most commonly used. In particular, as previously mentioned, it has been found that there is a reabsorption of radiation due to the cooler sodium atoms present near the arc tube wall, resulting in a loss of efficiency. The absorbed radiation is generated near the center of the arc discharge tube as a result of a plasma of ionized sodium vapor. Particular attention should be paid in this regard to FIGS. 5 and 6, which will be explained later.

In this invention, it has been experimentally determined that the presence of a metal halide such as iodine in the arc tube of a sodium vapor lamp significantly reduces the reabsorption phenomenon. In particular, sodium iodide in the center of the plasma arc dissociates, but sodium iodide near the arc tube wall does not dissociate at all. Therefore, there are no longer any helium atoms that would normally be located near the arc tube wall and act to reabsorb radiation from the central plasma region.

Instead, in this invention, iodide is present;
This iodide does not cause reabsorption problems. Therefore, as well as controlling the metal halide mold added to the arc tube, for example, the temperature of the arc charge storage section can be controlled. The vapor partial pressure of the metal halide can be controlled by
It turns out that it is possible to do this. In particular, it has been found desirable to control the ratio of the metal vapor partial pressure to the metal iodide partial pressure. In this way, the radial distribution of the atoms and ions can be controlled.

Furthermore, according to this invention, if sodium iodide is used in a lithium vapor lamp, a layer that contributes to the spectral output of the discharge lamp.
It should be noted in particular that it will be easy to include certain additives that will improve the color of the product as well as its color. In particular, thallium iodide can be added. As a result of this addition of -C, the following reversible reaction occurs within the arc tube.

T-J l+Na≧Na I+T, I! However, this reversible reaction means that the addition of pentium iodide to the arc tube filling causes the reaction to proceed to the left. However, this increases the spectral output from the iodide enriched metal. In this invention, the beneficial influence of sodium iodide on efficiency occurs independently of the presence of other iodides, such as thallium iodide.

As previously stated, the arc tube used in the discharge lamp of the present invention must be resistant to corrosion of the metal used. Further, the metal halide added to the arc discharge tube in accordance with the present invention must be a halide other than fluoride.

This is because fluorides are known to attack materials commonly used or available for use in arc discharge tubes.

As a common practice for metal vapor couplers, under operating conditions of discharge lamps approximately 1
This amount is sufficient to generate a partial pressure of steam up to 0 atmospheres.
Preferably, a limited amount of mercury is placed within the arc tube.

However, while certainly preferred, the inclusion of mercury is not absolutely necessary to practice this invention.

Furthermore, like mercury, the amount of water in the discharge lamp operating condition is about 1 to about 2
Preferably, a finite number of inert starting gases are also placed in the arc tube in an amount sufficient to generate a vapor partial pressure of 0.00 Torr. The inert starting gas is typically selected to be a gas such as argon krypton, gysenone or neon. The metal vapors used in the discharge lamp contemplated by this invention include alkali metals such as sodium, cesium, rubidium and potassium.

FIG. 2 depicts one type of high pressure metal/metal halide discharge lamp preferably used in the present invention. In particular, the discharge lamp of FIG. 2 includes a molybdenum thermal shield 30 disposed around both ends of the arc tube 10.

In particular, since sodium halides require much higher temperatures than metallic sodium, such heat conserving end shields are used in the arc tube to maintain the desired vapor pressure for the sodium to lium iodide species. Used around both ends to achieve this purpose.

FIG. 3 shows another type of high pressure metal/metal halide discharge lamp preferred for use in the present invention.

In particular, the discharge lamp of FIG. 3 includes an electrical resistance coil heater 41 disposed around a heat-resistant cylinder 40. In particular, the discharge lamp of FIG. The material of the cylinder 40 can be, for example, similar to the arc tube 10 or another reramic material.

Although it is shown that two such coils are used in the discharge lamp of FIG. 3, it goes without saying that one resistance heater may also be used. As shown in the drawings, the resistance heater is electrically connected in series with the arc discharge between the electrodes in the arc tube 10. Insulating supports 42 or the like can be used to protect this electrical series connection. The insulating support 42 acts to support the discharge tube 10 by attaching it to the arc tube termination conductor 25. This termination conductor may be used if external storage is not desired at one or both ends of the arc tube. or a type of arc tube termination that can be used when not required.Insulating support 4
2 is typically spot welded to the terminal conductor 25 and the conductive support 15, thus acting to support the arc tube 10.

However, it also has an electrically insulating effect, allowing the heating coil 41 to be connected in series with the discharge in the arc tube 10. Details of one type of such an insulating support structure are shown in FIG. In FIG. 4, separate electrical support members 42a,
It can be seen that 42c is disposed within a glass or ceramic ball 42b, which acts to provide electrical isolation between supporting metal portions 42a, 42C.

The problem of reabsorption in metal vapor lamps and the solution of this invention will be better understood by examining FIGS. 5 and 6. FIG. 5 is a graph showing plasma temperature as a function of position across the arc tube diameter. The center of the graph corresponds to the center of the arc tube. The ends of the graph correspond to the end faces of the arc tube wall. Figure 5 shows that the plasma temperature reaches a maximum value of about 4,500 °C at the center of the arc tube;
It also shows that the plasma (ionized vapor) temperature decreases to about 1,500 K at the arc tube wall. More importantly, curve A in Figure 6 shows that the sodium atom density in an ordinary high-pressure sodium lamp is at its minimum near the center of the arc tube, but as it approaches the inner surface of the arc tube wall, it decreases to approximately This indicates an increase of 2 or 3 times. The biggest cause of the radiation absorption problem solved by this invention is the presence of these 1-lium atoms near the surface of the arc tube wall. Curve B in Figure 6 is , shows the distribution of sodium atoms in a discharge lamp containing sodium iodide as the discharge medium. Therefore, by including sodium and sodium iodide in the discharge medium, It will be appreciated that the radial distribution of atoms, or more generally metal vapor species, can be controlled or optimized.

For example, the gaseous discharge medium containing xNa+yNa1 is
A distribution of lithium atoms intermediate between curves A and B in the figure can be produced.

From the foregoing, it will be appreciated that the present invention provides a new type of high intensity discharge pair. In particular, metal vapor lamps such as sodium to aluminum lamps have been used in the past, and lamps using metal halides have also been used, but this invention is not limited to metal/metal halide discharge lamps in this document a. It will be appreciated that this is a novel type of discharge lamp structure called. A particular advantage of the discharge lamp of this invention is that it contains metal halides along with metal vapors? The presence of F reduces the density of metal atoms near the arc tube wall. For this reason, discharge lamps are
The metal halide atoms that do not reabsorb the radiation generated in the central hot plasma become even hotter. In particular, it will be appreciated that the invention may be used in the construction of sodium/sodium iodide discharge lamps. Furthermore, the invention also allows the inclusion of color-improving additives within the discharge vessel.

Having described the invention in detail in terms of preferred embodiments,
Many modifications will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications that are possible within the scope of this invention.

[Brief explanation of the drawing]

Figure 1 is a side view of a typical high-pressure sl--lium steam lamp using the present invention, and Figure 2 is a discharge tube similar to Figure 1 except that it has a reflective end for heat preservation. Figure 3 is a side view of a discharge tube similar to Figure 1 except that separate storage heating means are provided at both ends of the arc discharge tube, Figure 4 is a side view of a discharge tube similar to that shown in Figure 3. Detailed side sectional view of an insulating support of type 5
Figure 6 is a graph showing the change in plasma temperature as a function of distance from the center of the arc tube, and Figure 6 is a graph showing the density of sodium atoms (also as a function of distance from the center of the arc tube), which is normally Curve A is the case of the metal vapor lamp of the present invention, and curve B is the case of the discharge lamp of the present invention. Explanation of main symbols 10...transparent arc tube, 11...outer transparent jacket,
14...Jinden Y A7 support. patent applicant

Claims (1)

[Scope of Claims] 1) A light-transmitting arc discharge tube having an outer light-transmitting jacket and electrodes disposed at both ends of the light-transmitting arc discharge tube; a quantity of mercury disposed within the arc discharge tube sufficient to produce a vapor partial pressure of from about 1 to about 2001-degrees under operating conditions of the discharge pair; a sufficient finite amount of inert starting gas, at least one volatile metal species disposed as an amalgam within said arc discharge tube, and said arc 1
11 a halide other than a fluoride of the metal species disposed in the arc discharge tube and means for making an electrical connection to the electrode, the arc discharge tube being resistant to erosion of the metal species; A pair of high-intensity arc discharges. 2. The high-intensity arc discharge lamp according to claim 1), wherein the arc discharge tube is made of a material resistant to sodium. 3) The high-intensity arc discharge lamp according to claim 1), wherein the arc discharge tube is made of a refractory ceramic. 4) A high-intensity arc discharge lamp according to claim 1, wherein the arc discharge tube is made of sintered polycrystalline alumina. 5) The high-intensity arc discharge lamp according to claim 1), wherein the arc discharge tube is made of alumina with a +M. 6) A high-intensity arc discharge lamp according to claim 1), wherein the arc discharge tube has an inner diameter of about 4 to about 18 mm. 7) The high-intensity arc discharge lamp according to claim 6), wherein the arc discharge tube has an inner diameter of about 8 to about 10 mm. 8) The high-intensity arc discharge lamp according to claim 1), wherein the inert starting gas is composed of a gas selected from the group consisting of argon, krybuton, xenon and neon. electric light. 9) A high-intensity arc discharge lamp according to claim 1), wherein the metal species is selected from the group consisting of sodium, cesium, rubidium, and potassium. 10) The high-intensity arc discharge lamp according to claim 1), wherein the metal halide is a thorium halide. 11) A high-intensity arc discharge lamp as claimed in claim 1, wherein means for suspending electrical connections supports said arc discharge tube within an outer envelope. 12. The high-intensity arc discharge lamp according to claim 1), wherein heat shields are arranged around both ends of the arc discharge tube. 13) A high-intensity arc discharge lamp according to claim 1, comprising means for heating at least one end of the arc discharge tube. 14) The high-intensity arc discharge lamp according to claim 13), wherein the heating means comprises an electric resistance heater arranged around both ends of the arc discharge tube. 15) The high-intensity arc discharge according to claim 14), wherein the heater is electrically connected in series with the arc discharge. 16) The high-intensity arc discharge lamp according to claim 1), which contains thallium as a volatile metal species disposed within the arc discharge tube. 17) In a method for controlling the radial distribution of volatile metal species in an arc tube of a high-intensity discharge lamp, a selected amount of a halide other than fluoride of the metal species is added to the arc along with the metal species. A method that includes installation within the jurisdiction. 18) In the method described in claim 17),
The method wherein the metal species is sodium. 19) In the method described in claim 17),
The method wherein the halide is sodium iodide.