JPH0864172A - Discharge lamp, its lighting device, and lighting system - Google Patents

Abstract

PURPOSE: To provide a discharge lamp, and its lighting device, and a lighting system, capable of preventing the rereplacement of a nitride modified layer, lengthen the life of the nitride modified layer, and preventing the reaction of a luminescent metal with a luminescent tube material and coming out of the luminescent metal to keep high lumen maintenance factor. CONSTITUTION: In a discharge lamp in which a luminescent material is sealed in a luminescent tube 1 having electrodes 5a, 5b for conducting discharge,and a nitride modified layer 3 formed by replacing an oxygen component for constituting a luminescent tube material with nitrogen is formed on the inner surface of the luminescent tube, an oxygen getter 9 for absorbing oxygen is sealed in the luminescent tube 1. The nitride modified layer 3 prevents the reaction of the luminescent material with the luminescent tube material to prevent decrease in luminous flux and to enhance luminous maintenance factor. By sealing the oxygen getter 9 in the luminescent tube, the oxygen getter adsorbs oxygen, the rereplacement by reaction of the nitride modified layer with oxygen is prevented to keep the condition of the nitride modified layer good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp such as a metal halide lamp, a mercury lamp or a high-pressure sodium lamp, a lighting device therefor, and a lighting device using the same.

[0002]

2. Description of the Related Art Generally, the arc tube of a high pressure metal vapor discharge lamp is
The material is selected from the viewpoints of excellent translucency, heat resistance, chemical resistance, and processability. In metal halide lamps and high-pressure mercury lamps, arc tubes made of quartz are used. In this case, an arc tube made of translucent ceramics such as alumina (Al ₂ O ₃ ) ceramics is used.

However, such a discharge lamp still has a problem that the luminous flux is lowered due to long-term use even if the above-mentioned arc tube material is selected. There are various causes of the decrease in the luminous flux, and one of them is that the luminous substance enclosed in the luminous tube reacts with the luminous tube material.

[0004] For example, in the case of a metal halide lamp, a metal halide enclosed in an arc tube made of quartz or a luminescent metal dissociated from the metal halide reacts with quartz, causing discoloration of quartz and transmission of visible light. Sex decreases. In addition, the luminous flux is also reduced due to the reduction of the luminescent metal. As a result, the luminous flux maintenance factor decreases.

Further, in the case of a high-pressure sodium lamp, sodium or sodium ions enclosed in an arc tube made of alumina ceramics react with the arc tube to produce a reaction product, so-called sodium disappears, which causes a luminous flux. Cause a decrease in

Further, in the case of a medium-pressure mercury lamp, mercury enclosed in an arc tube made of quartz is driven into the quartz,
The arc tube turns black. In order to eliminate such problems,
Japanese Patent Publication No. 57-44208 proposes a technique of coating the inner surface of the arc tube with a film made of silicon nitride (Si ₃ N ₄ ). When the silicon nitride film described in the above publication is formed on the inner surface of the arc tube, the silicon nitride film reduces the reaction between the light emitting metal and the arc tube material and prevents the emission of the light emitting substance. It is considered that the reduction of the luminous flux can be prevented and the luminous flux can be maintained high.

Further, Japanese Unexamined Patent Publication No. 62-262358 discloses a technique of applying an aluminum nitride coating to the inner surface of an alumina arc tube to lower the temperature of the central part of the arc tube and thereby reducing the loss of sodium. Has been done.

However, all of the means disclosed in these publications have a structure in which a special coating of silicon nitride or aluminum nitride is formed on the inner surface of the arc tube, so that the thermal expansion of the arc tube material and these coatings. Due to the difference, the silicon nitride film and the aluminum nitride film may be cracked, peeled, or dropped.

Regarding this point, the latter publication discloses that the film thickness of the aluminum nitride film may be 5 μm or less, but cracks may occur even when the film thickness is 5 μm or less. However, it is difficult to form a sufficiently effective film, and such a film has not been put to practical use at present.

From the above, the inventors of the present invention, instead of the above-mentioned coating, have a nitride modified layer formed by replacing the oxygen component of the oxide constituting the arc tube material with nitrogen on the inner surface of the arc tube. We proposed the technology that formed the.

That is, in the case of a metal halide lamp,
Quartz glass is used as the arc tube, and a nitriding modified layer is formed on the inner surface of the arc tube made of quartz. The nitriding reformed layer is a surface layer formed by substituting the nitrogen N for the oxygen component in silica SiO ₂ forming the arc tube material quartz. It is considered that when the inside of the valve is heated to a high temperature in an atmosphere of ammonia (NH ₃ ), the reaction shown in the following “Chemical formula 1” occurs, and the oxygen component of silica SiO ₂ is replaced with nitrogen N by such a reaction. Formed by nitriding and reforming.

[0012]

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When the nitriding reformed layer is formed on the inner surface of the arc tube in this manner, the nitriding reformed layer suppresses the reaction between the metal halide as the luminescent substance and the quartz of the arc tube material, Further, it is possible to prevent the light-emitting substance from falling out or being driven in, and thus to prevent the luminous flux from decreasing. Moreover, since the nitrided reformed layer is a reaction layer formed by substituting the oxygen component of the oxide constituting the arc tube material with nitrogen, unlike the case of the coating film, cracking, peeling, dropping, etc. There are advantages such as not having to worry about it occurring. From such a fact, it has been confirmed that when the nitrided modified layer is formed on the inner surface of the arc tube, the luminous flux maintenance factor is improved and the life is extended.

[0014]

However, as a result of further research conducted by the present inventors, the nitriding modified layer was found to contain oxygen O 2.
_In an atmosphere in which ₂ exists, oxygen O ₂ may be replaced with nitrogen N in the nitrided modified layer again at a high temperature, and the layer that has been nitrided and modified may return to an oxide layer, that is, a layer of silica SiO _2. I knew that.

The elimination of the nitriding reformed layer by such re-substitution impairs the function of the above-mentioned nitriding reformed layer, so that a reaction occurs between the metal halide as the luminescent substance and the quartz of the arc tube material. In addition, the light-emitting substance may come off or be driven in, resulting in a decrease in luminous flux.

In the meantime, in the case of manufacturing an arc tube, efforts have been made to avoid the introduction of impurities by cleaning the quartz glass forming the bulb and the constituent materials of the sealed electrode as much as possible. It is not possible to completely stop the invasion of H ₂ 0, and more or less water remains. Thus, when water H ₂ 0 exists in the arc tube, it is decomposed into hydrogen H ₂ and oxygen O ₂ , and oxygen is generated. Therefore, this oxygen may be replaced with nitrogen N in the nitriding and reforming layer, which may lead to a problem that the layer nitriding and reforming is returned to the oxide layer.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent re-replacement of the nitriding reformed layer, enable a long life of the nitriding reformed layer, and allow the luminescent metal and the luminescent metal to emit light. An object of the present invention is to provide a discharge lamp capable of preventing a reaction with a tube material, a light emitting metal coming off, and the like and maintaining a high luminous flux maintenance rate, a lighting device thereof, and a lighting device.

[0018]

According to the invention of claim 1, an arc tube, a means for generating a discharge in the arc tube, a luminescent material enclosed in the arc tube and emitting light by the discharge, and the arc tube. In a discharge lamp provided with a nitriding reforming layer formed on the inner surface of the arc tube, the oxygen component of the oxide constituting the arc tube material being replaced with nitrogen, and oxygen absorbing oxygen in the arc tube. It is characterized by enclosing a getter.

Here, the arc tube is made of a ceramic such as quartz or alumina. Further, the means for generating a discharge in the arc tube is an internal electrode,
Alternatively, it is an external electrode, or includes an electromagnetic induction coil or the like.

According to a second aspect of the present invention, in a metal halide lamp in which an arc tube is made of quartz and a metal halide is enclosed as a light emitting substance, the oxygen getter is a metal forming the enclosed metal halide. It is formed of the same metal or a metal that forms another metal halide.

The invention of claim 3 is characterized in that the oxygen getter is enclosed in the arc tube in the form of metal particles. According to a fourth aspect of the present invention, there is provided a discharge lamp according to any one of the first to third aspects, and a lighting circuit connected to a means for generating a discharge in the arc tube of the discharge lamp to maintain lighting. A lighting device for a discharge lamp, comprising:

An invention according to claim 5 is an illuminating device comprising the discharge lamp according to any one of claims 1 to 3 and a main body of a fixture containing the discharge lamp. .

[0023]

According to the invention of claim 1, since the getter for adsorbing oxygen is enclosed in the arc tube, oxygen O ₂ brought into the arc tube or released from the bulb wall or electrode material during lighting into the arc tube. The generated oxygen O ₂ will be adsorbed by the oxygen getter. Therefore, it is possible to prevent the oxygen O _{2 from} being replaced with the nitrogen N of the nitriding reformed layer and returning the layer which has been nitriding reformed to the oxide layer, that is, the layer of silica SiO ₂ . As a result, the nitrided modified layer is maintained for a long period of time, the reaction between the metal halide as the light emitting material and the quartz of the arc tube material is prevented, and the light emitting material is prevented from coming off or driving in. It is possible to prevent the decrease and maintain a high luminous flux maintenance factor.

According to the second aspect of the invention, in the case of the metal halide lamp, the oxygen getter forms the same metal as the metal forming the metal halide enclosed in the arc tube, or another metal halide. Since it is made of metal, the enclosed oxygen getter does not hinder the halogen cycle, and the advantages of the metal halide lamp can be utilized as they are.

According to the third aspect of the invention, since the oxygen getter is enclosed in the arc tube in the form of metal particles, the oxygen getter is easy to handle and the arc tube is easy to manufacture. According to the inventions of claims 4 and 5, it is possible to provide a lighting device and a lighting device having an excellent luminous flux maintenance factor.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment applied to a metal halide lamp shown in the drawings. FIG. 1 is a diagram showing the configuration of the arc tube of the metal halide lamp, FIG. 2 is a diagram showing the overall configuration of the metal halide lamp, and FIG.
Shows a cross-sectional view of an illuminating device using the metal halide lamp as a light source. In the overall configuration diagram of FIG. 2, 10 is an outer tube made of hard glass, the inside of the outer tube 10 is kept in a nitrogen gas atmosphere, and the arc tube 1 is housed in the outer tube 10. .

The arc tube 1 is, as shown in FIG.
At both ends of the bulb 2 made of quartz glass, the crushing sealing portion 4,
4 is formed. On the inner surface of the valve 2, for example, a nitrided modified layer 3 is formed over the entire surface. This nitrided modified layer 3
Is a surface layer formed by substituting nitrogen N for oxygen component O ₂ in silica SiO ₂ forming quartz which is the material of the arc tube.

When the valve 2 is heated to a high temperature in an atmosphere of ammonia (NH ₃ ), for example, the nitriding modified layer 3 as described above, nitrogen N in ammonia (NH ₃ ) and silica forming quartz are formed. Since the oxygen component O ₂ in SiO ₂ is replaced and the reaction shown in the above “Chemical formula 1” occurs, the nitriding modification is performed.

Such a modified nitride layer 3 is shown in FIG. 1 (B).
As shown in the figure, the nitrogen concentration changes continuously from the surface of the valve 2 toward the inside of the valve wall, and there is no clear boundary, but the depth s to the estimated boundary is s.
Is formed to be 0.05 μm or more, for example, about 5 μm.

The main electrodes 5a and 5a are respectively attached to the sealing portions 4 and 4 formed at both ends of the valve 2 constructed as described above.
5b is sealed, and a starting auxiliary electrode 6 is sealed near one of the main electrodes 5a.

The main electrodes 5a and 5b are constructed by winding an electrode coil 52 made of tungsten around an electrode shaft 51 made of tungsten containing tungsten W or thorium Th. Dysprosium Dy ₂ O ₃ , scandium oxide Sc ₂ O ₃
An electron emitting substance (emitter) composed of, for example, is applied. The auxiliary electrode 6 is formed of a tungsten wire.

The main electrodes 5a and 5b and the auxiliary electrode 6
Are connected to external lead wires 8 through metal foil conductors 7 such as molybdenum Mo sealed in the sealing portions 4 and 4. In such a bulb 2, a predetermined amount of mercury Hg,
Metal halides such as scandium iodide ScI ₃
And sodium iodide NaI and argon Ar as a rare gas for starting are enclosed.

Further, a getter (oxygen getter) 9 for adsorbing oxygen in the arc tube is enclosed in the arc tube 1. The oxygen getter 9 may be aluminum Al or the like as long as it is a metal having a strong property of adsorbing oxygen, but in this embodiment, scandium iodide S used as a light emitting substance.
Since a metal halide composed of cI ₃ and sodium iodide NaI is used, the same metal as the metal forming the metal halide, for example, scandium metal Sc is used. Such a scandium metal Sc
The oxygen getter 9 is made of metal particles in the arc tube 1 and is encapsulated by about 0.1 mg in the case of a 100 W class lamp.

The arc tube 1 having such a configuration is housed in the outer tube 10 as shown in FIG. That is,
The both end sealing portions 4 and 4 of the arc tube 1 are holders 11a and 11a.
It is supported by supports 12a and 12b via b.
One support 12 a is welded to one conductive wire 14 a sealed in the stem 13, and the other support 12 b is attached to the top of the outer tube 10.

One main electrode 5a of the arc tube 1 is electrically connected to the one support 12a. Arc tube 1
The other main electrode 5b is connected to the stem 1 via the lead wire 15.
3 is connected to the other conductive line 14b sealed. Further, the auxiliary electrode 6 of the arc tube 1 is connected to the other conductive line 14b via the starting resistor 18.

The one conductive wire 14a is connected to the base 16 attached to the end of the outer tube 10, and the other conductive wire 14b is connected to the external terminal 17 of the base 16.

The metal halide lamp having such a structure is used as a light source of a lighting device as shown in FIG. 3, for example. In FIG. 3, reference numeral 30 denotes a lighting fixture body,
The housing structure has an inner surface having a reflecting surface 31 and an opening on the lower surface or one side surface. A front cover 32 is attached to the opening of the lighting fixture body 30. The side wall of the lighting fixture body 30 has a socket 33.
2 is attached, and the base 16 of the metal halide lamp shown in FIG. 2 is screwed into the socket 33 and attached to the fixture body 30.

The socket 33 is adapted to be connected to a commercial power source 36 via a lighting circuit 35 which is attached to the instrument body 30 or which is provided outside the instrument body 30 and includes a ballast.

In the illuminating device having such a structure, when the metal halide lamp is connected to the commercial power source 36, the starting pulse voltage from the lighting circuit 35 including the ballast is supplied to the auxiliary electrode 6 and one of the main electrodes 5a adjacent thereto. And between the main electrodes 5a and 5b. Therefore, an auxiliary discharge is started between the auxiliary electrode 6 and one of the main electrodes 5a adjacent thereto, and this auxiliary discharge is transferred to the main discharge between the main electrodes 5a and 5b, so that the arc tube 1 is discharged. . By this discharge,
Metal halides, such as scandium iodide ScI3 and sodium iodide NaI, enclosed in the arc tube 1 emit light.

The light emitted from such a metal halide lamp is reflected by the reflecting surface 31 formed on the inner surface of the instrument body 30.
The light is reflected by and is radiated to the outside through the front cover 32 of the opening.

In the metal halide lamp used as the light source, since the nitriding modified layer 3 is formed on the inner surface of the arc tube 1, the metal halide enclosed in the arc tube 1 or this metal halide is used. The dissociated luminescent metal such as scandium Sc or sodium Na is prevented from coming into contact with quartz, and the metal halide or the luminescent metal such as scandium Sc or sodium Na is prevented from reacting with quartz. Therefore, the corrosion resistance of the quartz is improved, discoloration is prevented, and reduction of the luminous metal from the arc tube 1 is prevented, so that the decrease in luminous flux is reduced and the luminous flux maintenance factor can be increased.

In addition, since the nitride reforming layer 3 is a layer having a reaction structure in which the oxygen O ₂ component in the silicon oxide SiO ₂ constituting the arc tube 1 is replaced with nitrogen N ₂ , the arc tube is modified. No need to worry about cracking, peeling, falling off, etc.

Since the oxygen getter 9 is enclosed in the arc tube 1 as described above, oxygen O ₂ brought into the arc tube 1 or released from the bulb wall or electrode material during lighting into the arc tube 1. The generated oxygen O ₂ is adsorbed by the oxygen getter 9. Therefore, it is possible to prevent oxygen O _{2 from} being replaced again as nitrogen N of the nitriding modified layer 3 and returning the layer which has been nitriding modified to the oxide layer, that is, the layer of silica SiO ₂ . From this, the nitriding modified layer can be maintained for a long period of time, and the function of the nitriding modified layer can be maintained.

Therefore, it is possible to prevent the reaction between the metal halide and the quartz, prevent the light emitting substance from coming off or driving in, prevent the decrease of the luminous flux, and maintain a high luminous flux maintenance factor. For example, a 100 W rated input metal halide lamp having an inner diameter of the arc tube 1 of 10.5 mm and a distance between electrodes of 18 mm, which is composed of scandium iodide ScI3 and sodium iodide N.
When a total amount of 10 mg is enclosed with aI in a weight ratio of 1: 5, in the conventional lamp in which the nitrided modified layer 3 is not formed on the inner surface of the arc tube 1, the luminous flux maintenance factor after 6000 hours of lighting is 50%.
%, The depth s is 5 μm on the inner surface of the arc tube 1.
In the lamp of the present invention in which the nitriding modified layer 3 is formed, the luminous flux maintenance rate after lighting for 6000 hours becomes 65% unless the oxygen getter 9 is enclosed, and the effect of forming the nitriding modified layer 3 is confirmed. However, when the oxygen getter 9 is further enclosed inside the arc tube 1, the luminous flux maintenance factor after lighting for 6000 hours is 72%, and the effect of enclosing the oxygen getter 9 has been confirmed.

The depth s of the modified nitride layer 3 is 0.05 μm.
If it is m or more, it is effective in improving the corrosion resistance of quartz,
If it is about μm, the effect is sufficiently exhibited. A lighting device and a lighting device that use such a metal halide lamp as a light source are devices having an excellent luminous flux maintenance factor.

In the metal halide lamp of the first embodiment, an example in which scandium iodide ScI ₃ and sodium iodide NaI are used as metal halides will be described, and a case where scandium metal Sc is used as the oxygen getter 9 will be described. Although described, the metal halide is not limited to these, and may be a halide of a rare earth metal, a halide of an alkali metal, or a halide of indium, thallium, or the like.

In the case of a rare earth metal halide, for example, dysprosium iodide DyI ₃ is used. In such a case, it is preferable to use dysprosium metal Dy as the oxygen getter 9.

As described above, if the same metal halide as the light emitting metal sealed in the arc tube is used as the oxygen getter 9, an undesired halogen cycle will not occur, so that stable light emitting characteristics can be obtained.

By encapsulating the oxygen getter 9 in the form of metal particles, the oxygen getter 9 can be manufactured without changing the process of manufacturing the arc tube, and the oxygen getter 9 is handled in the form of metal particles. Is also easy and can be easily enclosed in the arc tube.

Although the metal halide lamp has been described in the above embodiment, the present invention is not limited to this, and can be applied to a medium pressure mercury lamp, a high pressure sodium lamp and the like.

That is, the mercury lamp is different from the metal halide lamp in that mercury Hg and a rare gas for starting such as argon Ar are enclosed in the arc tube. However, in the mercury lamp, mercury ions Hg ⁺ are implanted into quartz. As a result, blackening of the arc tube occurs. That is, there are fine voids on the surface of the quartz, and the mercury ions Hg ⁺ are drawn into the fine voids on the quartz surface by the OH ⁻ inside the glass and the negative charges on the glass surface for implantation. Therefore, blackening of quartz tends to be promoted.

On the other hand, when the nitriding modified layer is formed on the inner surface of the quartz, the mercury enclosed in the arc tube is prevented from coming into contact with the quartz, and the mercury ions Hg ⁺ are formed into fine voids on the quartz surface. The blackening of the quartz is prevented, and the luminous flux maintenance factor is improved.

Also in this case, by enclosing the oxygen getter, the nitriding modified layer can be maintained for a long time.
In the case of a high-pressure sodium lamp, the arc tube is made of translucent ceramics such as polycrystalline or single crystal alumina or sapphire. The arc tube has a predetermined amount of mercury Hg, sodium Na, And xenon Xe gas as a rare gas for starting is enclosed.

In the case of the high-pressure sodium lamp having such a structure, the alumina Al ₂ O ₃ forming the arc tube and sodium Na as the light-emitting substance react with each other to form a crystal such as a needle crystal, and Needle-like crystals grow and sodium disappears, but when a nitriding reformed layer is formed on the inner surface of the arc tube, the nitriding reformed layer prevents the reaction between sodium Na and alumina Al ₂ O ₃ and causes needles to disappear. It prevents the growth of crystals such as spheroidal crystals and prevents the disappearance of sodium. Therefore, the reduction of the luminous flux is suppressed, and the luminous flux maintenance factor can be increased.

Further, according to the present invention, like the inductively coupled electrodeless discharge lamp, a high frequency excitation coil is provided outside the arc tube,
A lamp that induces plasma discharge inside the arc tube to emit light by the high-frequency electromagnetic field generated by the high-frequency excitation coil can also be implemented.

In addition, although the above-mentioned embodiment describes the arc tube of both-ends sealed type, the present invention is also applicable to the one-end sealed arc tube in which the sealing portion is formed only at one end. is there.

[0057]

As described above, according to the first aspect of the invention, since the getter for adsorbing oxygen is enclosed in the arc tube, the oxygen O ₂ released in the arc tube is adsorbed by the oxygen getter. Therefore, it is possible to prevent the oxygen O _{2 from} being replaced with the nitrogen N of the nitride-modified layer again and returning the nitride-modified layer to the oxide layer, that is, the layer of silica SiO ₂ . As a result, the nitriding modified layer remains nitrided and modified for a long period of time, the reaction between the light emitting material and the arc tube material is prevented, and thus the decrease in luminous flux is prevented, so that a high luminous flux maintenance factor is maintained. You can

According to the second aspect of the present invention, in the case of the metal halide lamp, the oxygen getter forms the same metal as the metal forming the metal halide enclosed in the arc tube, or another metal halide. Since it is made of metal, the enclosed oxygen getter does not hinder the halogen cycle, and the advantages of the metal halide lamp can be utilized as they are.

According to the third aspect of the invention, since the oxygen getter is enclosed in the arc tube in the form of metal particles, the oxygen getter is easy to handle and the arc tube is easy to manufacture. According to the inventions of claims 4 and 5, it is possible to provide a lighting device and a lighting device having an excellent luminous flux maintenance factor.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (A) is a cross-sectional view of an arc tube of a metal halide lamp, (B) is a cross-sectional view of a portion indicated by B in (A). The figure which shows a quality layer typically.

FIG. 2 is a configuration diagram showing an entire metal halide lamp of the same embodiment.

FIG. 3 is a diagram showing a lighting device and a lighting device using the metal halide lamp of the embodiment as a light source.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arc tube of metal halide lamp 3 ... Nitrided reforming layer 5a, 5b ... Electrode 9 ... Oxygen getter 10 ... Outer tube 30 ... Lighting fixture body 35 ... Lighting circuit

Claims (5)

[Claims] 1. An arc tube, means for generating an electric discharge in the arc tube, a luminescent substance enclosed in the arc tube and emitting light by the discharge, and an arc tube material formed on an inner surface of the arc tube. A nitride reforming layer in which the oxygen component of the oxide constituting the nitrogen is replaced by nitrogen, and a discharge lamp characterized in that an oxygen getter for absorbing oxygen is enclosed in the arc tube. . 2. In a metal halide lamp in which an arc tube is made of quartz and a metal halide is enclosed as a light emitting material, the oxygen getter is the same metal as the metal forming the enclosed metal halide, or The discharge lamp according to claim 1, wherein the discharge lamp is formed of a metal that forms another metal halide. 3. The discharge lamp according to claim 1, wherein the oxygen getter is enclosed in the arc tube in the form of metal particles. 4. A discharge lamp according to any one of claims 1 to 3, and a lighting circuit connected to a means for generating a discharge in the arc tube of the discharge lamp to maintain lighting. A lighting device for a discharge lamp characterized in that 5. A lighting device comprising: the discharge lamp according to claim 1; and a main body of a fixture that houses the discharge lamp.