JPH07240184A - Ceramic discharge lamp, projector device using this lamp, and manufacture of ceramic discharge lamp - Google Patents

Abstract

PURPOSE:To provide a ceramic discharge lamp in which a blocking body prevents overheating of a glass adhesive, melting or chemical reaction of the glass adhesive is prevented, and life is lengthened, and a projector device using this discharge lamp, and manufacturing method for the ceramic discharge lamp. CONSTITUTION:A blocking body 5 is airtightly bonded to the opening end of an arc tube 1 made of translucent ceramic through a glass adhesive 6, and an electrode 10 connected to a conductive means 8 is fixed to the inner end of the blocking body. In a ceramic discharge lamp obtained by sealing a luminescent metal which becomes excess during lighting and noble gas in the arc tube, a gap 7 in which excess luminescent metal is condensed is formed between the inner surface of the arc tube and the blocking body. During lighting, the gap becomes the coldest place, the excess luminescent metal is condensed in the gap, and the contact of the glass adhesive to the high temperature gas is prevented by the condensed luminescent metal. Heating of the glass adhesive by high temperature gas is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic discharge lamp in which an open end of an arc tube made of translucent ceramic is sealed with a closing body, and an electrode is attached to an inner end of the closing body, and a ceramic discharge lamp using the same. And a method for manufacturing a ceramic discharge lamp.

[0002]

2. Description of the Related Art For example, a light projecting device used in a color liquid crystal projector or the like comprises a lamp which is a light source and a reflector which reflects light emitted from the lamp. And a metal halide lamp with excellent color rendering is used. Since such a light projecting device needs to reflect and condense light, it is desirable to use a point light source whose light distribution can be easily controlled. Therefore, recently, a short arc type in which the distance between electrodes is set to 15 mm or less is used. A metal halide lamp has been developed, and such a small metal halide lamp has already been put to practical use as a light source.

However, recently, the range of application of this kind of short arc type metal halide lamp is expanding, and therefore, further improvement in efficiency of the short arc type metal halide lamp has been demanded. In order to improve the efficiency of the lamp, it is sufficient to increase the input power supplied to the lamp. However, in this case, the tube wall load becomes high and the arc tube temperature rises excessively. In the conventional short arc type metal halide lamp, quartz glass is used as the arc tube material. Quartz glass is hard and has excellent heat resistance and halogen resistance, but the tube wall load is increased as described above, and for example, the tube wall load is 40 to 100 W /
When it reaches about cm ² , it may exceed the limit that quartz glass can withstand, causing blackening and devitrification at an early stage, and significantly shortening the lamp life.

From this, for example, the actual Kaihei 2-1
As disclosed in Japanese Patent Publication No. 29664, a light-emitting tube of a high output, high load type short arc type metal halide lamp is made of translucent alumina, single crystal or polycrystal ceramic such as sapphire or garnet. The use of tubes is being considered. Such a translucent ceramic tube has excellent heat resistance and corrosion resistance, and therefore has excellent life characteristics as compared with quartz.

However, since the ceramic tube has poor workability, when closing the open end of the tube, a molten glass adhesive is used at the open end of the ceramic tube as disclosed in the above publication. Therefore, a structure in which a closed body of another member is airtightly joined is adopted.

[0006]

However, in the conventional case, since the glass adhesive is exposed to the discharge space, the heat of the high temperature gas in the discharge space is directly transmitted to the glass adhesive and the glass adhesive is heated. It was As a glass adhesive,
For example, Al ₂ O ₃ —SiO ₂ system, or Al ₂ O ₃ —C
Since aO-BaO type glass solder is used, and the melting point of this type of glass adhesive is lower than that of ceramics (1,500 to 1,700 ° C.), if this glass adhesive is excessively heated, it will melt. I have a concern. When the adhesive melts, the adhesive strength decreases.

When the temperature of the glass adhesive increases, a chemical reaction occurs with the metal halide enclosed in the arc tube, resulting in defective adhesion. For this reason, in the conventional case, not only the bonding strength of the closing body is deteriorated due to the deterioration of the glass adhesive, but also the leakage may occur.

Therefore, it is an object of the present invention to prevent excessive heating of the glass adhesive in which the closing body is joined to the arc tube, to prevent melting and chemical reaction of the adhesive, and to improve the life characteristics of the ceramic. An object of the present invention is to provide a discharge lamp, a floodlighting device using the same, and a method for manufacturing a ceramic discharge lamp.

[0009]

According to a first aspect of the present invention, a closed body is airtightly joined to an open end portion of a light emitting tube made of translucent ceramic through a glass adhesive. A luminescent metal and a rare gas which have a conductive means for conducting the inside and the outside and which have an electrode connected to the conductive means attached to the inner end portion of the closing body and which are in excess of the amount evaporated during lighting in the arc tube. In the ceramic discharge lamp in which is enclosed, a gap is formed between the inner surface of the arc tube, the closing body, and the outer surface, and a gap portion is formed which communicates with the discharge space and collects excess light emitting metal.

The invention according to claim 2 is characterized in that the gap portion has a size such that an excessive amount of aggregated luminescent metal is retained by a capillary phenomenon. According to the invention of claim 3, the gap is
It is characterized by forming at least one groove extending in the axial direction formed between the inner surface of the arc tube and the outer surface of the closing body.

According to a fourth aspect of the invention, the arc tube is provided with a thin tube portion at the end of the bulging portion, and the closing body is joined to the opening end of the thin tube portion via a glass adhesive. The inner end portion of has a length substantially equal to the position where the thin tube portion continues to the bulging portion, and the gap portion is formed between the outer surface of the closing body and the inner surface of the thin tube portion. To do.

The invention of claim 5 is characterized in that a heat radiating means is provided at the end of the arc tube in which the closing body is sealed with a glass adhesive. The invention of claim 6 is characterized in that the luminescent metal is a metal halide.

According to a seventh aspect of the present invention, there is provided a ceramic discharge lamp according to any one of the first to sixth aspects, and a reflector for housing the discharge lamp and reflecting light emitted from the discharge lamp. A floodlighting device characterized by being provided.

According to an eighth aspect of the present invention, a predetermined amount of luminescent metal is supplied from an open end of an arc tube made of translucent ceramic,
At the open end of the arc tube, a plug having an electrically conductive portion for conducting the inside and outside of the arc tube in advance and having an electrode joined to the inside end is inserted to insert the inside surface of the end of the arc tube and the plug. A gap is formed between the arc tube and the arc tube, the gas around the arc tube is replaced with gas to change the atmosphere of the arc tube to the atmosphere of the rare gas through the open end, and the open end of the arc tube and the closing body are closed. It is a method for manufacturing a ceramic discharge lamp, which is characterized by joining with a molten glass adhesive.

[0015]

According to the first aspect of the present invention, during lighting, the gap formed between the inner surface of the arc tube end portion and the closing body and the outer surface becomes the coldest portion, and the surplus light emitting metal aggregates and accumulates therein. As a result, the aggregated luminescent metal blocks the contact between the glass adhesive and the high-temperature gas on the discharge space side and thermally isolates it, so that the temperature rise of the glass adhesive is prevented.

According to the second aspect of the invention, the size of the gap portion is set to a size in which the aggregated excess luminescent metal is retained by the capillary phenomenon, so that the aggregated luminescent metal is accumulated in the gap portion by the capillary phenomenon. It will be held and will surely accumulate in the gap.

According to the third aspect of the present invention, since the gap portion is constituted by at least one groove extending in the axial direction formed between the inner surface of the arc tube and the outer surface of the closing body, it is circumferentially continuous. It becomes easier to position the center of the closing body that can be inserted into the end portion of the arc tube, and it is easier to hold the luminescent metal aggregated by the capillary phenomenon as compared with the space where

According to the invention of claim 4, since the arc tube is provided with the thin tube portion at the end of the bulging portion and the closing member is joined to the thin tube portion, it is easy to manufacture a lamp having a short inter-electrode distance. ,
In addition, the coldest portion is likely to be generated in the thin tube portion, and the gap portion can be reliably formed between the inner surface of the thin tube portion and the outer surface of the closing body while using such a lamp.

According to the invention of claim 5, the end portion of the arc tube in which the closing body is sealed via the glass adhesive is cooled by the heat radiating means, so that the thermal deterioration of the glass adhesive can be further reduced. it can.

According to the invention of claim 6, it is effective when a high efficiency and high color rendering short arc type metal halide lamp is lit by a high load. According to the invention of claim 7, a high efficiency and high color rendering short arc type metal halide lamp can be used as a light source close to a point light source, and the light reflected by the reflector can be easily controlled. According to the invention of claim 8, the open end portion or the narrow tube portion of the arc tube can be used as the exhaust pipe, and no special exhaust pipe is required.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIG. FIG. 1 shows a short arc type metal halide lamp, and 1 is an arc tube. The arc tube 1 is made of translucent alumina, single crystal or polycrystal ceramic such as sapphire or garnet, and has a spherical or elliptic spherical bulging portion 2 formed at the center thereof. The thin tube portions 3 and 3 each having a diameter smaller than that of the two are integrally formed at both ends thereof.

The bulging portion 2 is formed to have a major axis of about 15 mm and a minor axis of about 11 mm (both are outer diameters and inner diameters on the minor axis side are about 9 mm), and the inner volume is almost equal. It is 0.9 CC. The outer diameter of the thin tube portions 3 is 4.0.
mm (inner diameter 2.0 mm) and the length is approximately 20 mm, which is a cylindrical shape.

If necessary, the inner surface of the bulging portion 2 and the inner surfaces of the thin tube portions 3 and 3 may include scandium oxide ScO ₃ and dysprosium oxide Dy ₂ in order to protect the ceramic from a metal halide enclosed therein. A protective film 4 made of at least one of O ₃ is coated.

The open end portions of the thin tube portions 3 and 3 are closed bodies 5 and 5.
It is airtightly closed by 5. The closing bodies 5 and 5 are made of single crystal or polycrystalline ceramics such as alumina, sapphire, garnet, etc.
It has a rod shape that can be inserted into the inside. This block 5, 5
Has an outer diameter of, for example, about 1.0 to 1.9 mm and a length of 20 to 30 mm, and has a slightly large diameter portion at its outer end portion, and the large diameter portion is the glass adhesive 6 , 6 are joined to the open ends of the thin tube portions 3, 3. The closing bodies 5 and 5 are attached such that the inner end surfaces thereof are substantially equivalent to the positions where the thin tube portions 3 and 3 and the bulging portion 2 are continuous, that is, the roots of the thin tube portions 3 and 3. By such joining, the arc tube 1 is provided between the inner surfaces of the thin tube portions 3 and 3 and the outer surfaces of the closing bodies 5 and 5 rather than the glass adhesives 6 and 6.
The gaps 7, 7 are formed on the center side of the. That is, one of the gaps 7 and 7 along the axial direction of the thin tube portions 3 and 3 faces the sealing portion joined by the glass adhesives 6 and 6, and the other end thereof is the discharge space in the bulging portion 2. Is in communication with. The gaps 7 and 7 have a clearance dimension of 0.
The size is set to about 05 to 0.5 mm, and is set to a size such that when a surplus portion of a metal halide described later is aggregated, the surplus metal accumulates in the gap portions 7, 7 due to a capillary phenomenon.

As the glass adhesives 6 and 6, for example, Al ₂ O ₃ --SiO ₂ system or Al ₂ O ₃ --CaO-- is used.
A BaO-based glass solder is used and is also called frit glass.

The closures 5 and 5 have conductive means along the axial direction. In the case of this example, this conductive means divides the closing bodies 5, 5 into, for example, two along the axis, and molybdenum Mo or platinum P is provided along one of the divided surfaces along the axial direction.
A liquid obtained by dissolving a powder of a conductive metal such as t in a solvent is applied and fired to form the lead wire members 8 and these divided bodies are hermetically joined.

Terminal portions 9, 9 connected to the lead wire members 8, 8 are formed on the outer end portions of the closing bodies 5, 5. These terminal portions 9 and 9 are also formed by applying a liquid obtained by dissolving a powder of a conductive metal such as molybdenum Mo or platinum Pt in a solvent to the outer surface of the outer end portions of the closing bodies 5 and 5 and firing the same. is there.

The electrodes 10, 10 are attached to the inner ends of the closing bodies 5, 5. Electrode 10
Is formed by winding an electrode coil 12 made of tungsten a plurality of times around the tip end of an electrode shaft 11 made of tungsten. The electrode coil 12 has, for example, Dy ₂ O ₃ −.
An electron emitting material (emitter) such as Y ₂ O ₃ —La ₂ O ₃ is applied.

In such an electrode 10, the end of the electrode shaft 11 is fitted into the hole formed in the inner end of the closing body 5, whereby the electrode 10 is electrically connected to the lead wire member 8. It is connected to the. The electrode shaft 11 is mechanically supported by the closing body 5 by fitting the electrode shaft 11 into the hole of the closing body 5 and then firing the closing body 5.

The pair of electrodes 10, 10 face each other in the bulging portion 2 of the arc tube 1, and the electrodes 10,
The distance between the tip portions of 10, that is, the distance L between the electrodes is, for example, 1
It is set to 5 mm or less, specifically 6 mm.

Mercury as a buffer metal, a metal halide as a light emitting metal, and a rare gas such as argon are sealed in the arc tube 1. As the metal halide, for example bromide dysprosium DyBr _3, dysprosium iodide DyI _3, cesium iodide CsI, tin bromide SnBr _2, and the like indium bromide InBr and thallium bromide TlBr is employed, vaporization during lighting The metal halide is contained in excess of the amount used.

Such an arc tube 1 has a capacity of 150 W during lighting.
~ 250W of power, for example 50-60 from a commercial power source
By supplying an AC cycle of Hz or a high frequency of 250 to 400 Hz from a high frequency power source 50 converted by an electronic ballast, a tube wall load Z (a value obtained by dividing the input power W by the inner surface area Scm ² of the arc tube, Z = W / S) is 40 to 1
It is used under a large load condition such as 00 W / cm ² .

There is an advantage that the pulsation of the light output can be prevented by turning on the lamp with a high frequency of 250 to 400 Hz. The arc tube 1 uses the thin tube portion 3 as an exhaust tube. That is, a method of sealing the arc tube 1 will be described.

That is, the arc tube 1 has one thin tube portion 3
Then, the one closed body 5 to which the electrode 10 has been joined in advance is airtightly joined by the glass adhesive 6. And the other thin tube portion 3
A predetermined amount of mercury and a metal halide are introduced into the arc tube 1 from the opening end of the above, and the other closing body 5 to which the electrode 10 is bonded in advance is inserted into the other thin tube portion 3. In this state, at least the other end of the arc tube 1 is covered with an airtight container (not shown), and the interior of the airtight container, that is, the periphery of the upper end of the arc tube 1 is gas-replaced and vacuumed. As a result, the air in the arc tube 1 is removed from the other thin tube portion 3. After that, argon Ar gas is supplied into the airtight container to change to an argon gas atmosphere of a predetermined pressure. As a result, the argon gas enters the arc tube 1 through the other thin tube portion 3, and the inside of the arc tube 1 is changed to an argon gas atmosphere having a predetermined pressure.

When such gas replacement is completed, a glass adhesive 6 is placed at the ends of the other thin tube portion 3 and the other closing body 5, and is heated and melted by means such as high frequency induction heating. . Then, the molten glass adhesive 6 flows into the gap between the thin tube portion 3 and the closing body 5, and these thin tube portions 3
And the occlusion body 5 so as to join them.

The operation of the first embodiment having such a configuration will be described. When the arc tube 1 is turned on, the excess metal halide tends to aggregate in the coldest part of the arc tube 1. In the arc tube 1, the coldest part is a part apart from the expanded diameter part 2 which is the discharge space.
The gaps 7 and 7 formed between the inner surfaces of the thin tube portions 3 and 3 and the outer surfaces of the closing bodies 5 and 5 are the coldest portions, and therefore, excess metal halide is condensed in these gaps 7 and 7. That is, the gaps 7 and 7 are pools where excess metal halides are aggregated and collected.

When excess metal halide accumulates in the gaps 7, 7, the end portions of the closing bodies 5, 5 are connected to the thin tube portions 3, 5.
The glass adhesives 6 and 6 bonded to the opening of 3 are separated from the discharge space by the aggregated metal halide. In other words, the glass adhesives 6 and 6 and the discharge space are separated by the excess metal halide accumulated in the gaps 7 and 7, and the glass adhesives 6 and 6 come into contact with the high temperature gas in the discharge space. Is blocked.

Therefore, the glass adhesives 6, 6 are prevented from being excessively heated during lighting. By the way, the electrode 10
The temperature of the coldest part near the root of is about 700 ° C, but the temperature of the glass adhesives 6 and 6 can be suppressed to about 400 ° C. Therefore, melting of the glass adhesives 6 and 6 having a melting point of about 1500 to 1700 ° C. is prevented,
Adhesion failure is prevented.

Further, since the temperature rise of the glass adhesives 6 and 6 is suppressed, the chemical reaction between the glass adhesives 6 and 6 and the metal halide enclosed in the arc tube 1 is prevented. Adhesion failure is prevented.

From the above, the glass adhesive 6,6
Is prevented, the joint strength of the closures 5, 5 is maintained,
Leakage is prevented for a long period of time. In this case, the clearances 7 and 7 are set to have a clearance dimension of about 0.05 to 0.5 mm, and when the excess portion of the metal halide is agglomerated, the excess metal causes the gap portion 7 and 7 due to the capillary phenomenon. 7
Since the size is such that the excess metal is retained, the excess metal is reliably retained, and the retained excess metal provides a reliable heat shield action.

Further, in the arc tube shape of the above embodiment, thin tube portions 3 and 3 are provided at both ends of the bulging portion 2, and these thin tube portions 3 and 3 are provided.
Because of the structure in which the closing bodies 5 and 5 are joined to each other, a light emitting space is formed in the bulging portion 2, light is emitted from the spherical or elliptical spherical surface, and the emission direction spreads. Then, the distance L between the electrodes is shortened in the bulging portion 2 and the electrodes 10,
It is easy to dispose 10 in opposition to each other, and thus it is easy to make a high efficiency and high color rendering short arc type metal halide lamp. Moreover, since the thin tube portions 3 and 3 extend away from the bulging portion 2,
It becomes easy to generate the coldest part in the thin tube parts 3 and 3.

Further, according to the above-mentioned sealing method,
One of the thin tube portions 3 of the arc tube 1 can be used as an exhaust pipe, and no special exhaust pipe is required. In the above-mentioned embodiment, the conductive means formed on the closing bodies 5 and 5 applies a liquid obtained by dissolving powder of a conductive metal such as molybdenum Mo or platinum Pt to the divided surfaces of the closing bodies 5 and 5 to apply this. Although the lead wire members 8 and 8 are formed by firing, as conductive means, molybdenum Mo, platinum Pt, or the like is used on the outer surface of the closing bodies 5 and 5 as in the second embodiment shown in FIG. Alternatively, the lead wire member 80 may be formed by applying a liquid in which a powder of a conductive metal is applied and firing the liquid.

As another structure, the electrode shaft 11 of the electrode 10 shown in FIG. 1 is inserted into the closing member 5 by extending it over substantially the entire length of the closing member 5, and the electrode shaft 11 is connected to the terminal portion 9. It may have a different structure.

Further, the entire blocking body 5 is made of tungsten W.
A powder of alumina (Al ₂ O ₃ ) may be mixed and fired to obtain a conductive sintered body. Further, in the above-described embodiment, the gap portion 7 formed between the glass adhesive 6 and the discharge space is the circumferential direction formed between the inner surface of the thin tube portions 3 and 3 and the outer surface of the closing bodies 5 and 5. However, as in the third embodiment shown in FIG. 3, the axial direction formed on at least one of the outer surfaces of the closing bodies 5 and 5 or the inner surfaces of the thin tube portions 3 and 3 is continuous. At least one groove 7 extending to
It may be formed by 0, 71.

According to the third aspect of the invention, since the gap portion is constituted by at least one groove extending in the axial direction formed between the inner surface of the arc tube and the outer surface of the closing body, it is circumferentially continuous. It becomes easier to position the center of the closing body that can be inserted into the end portion of the arc tube, and it is easier to hold the luminescent metal aggregated by the capillary phenomenon as compared with the space where

Furthermore, in the case of the first embodiment, the closing members 5 and 5 are hermetically sealed to the thin tube portions 3 and 3 formed at both ends of the arc tube 1 via the glass adhesives 6 and 6, respectively. Although an example of joining is shown, the present invention is not limited to this, and only one end of the arc tube 1 is airtightly joining the closing body 5 to the arc tube 1 using the glass adhesive 6. Good. That is, FIG. 4 shows an arc tube having a structure in which only one end of the arc tube 1 is sealed with the glass adhesive 6. In this embodiment, the end portion on the right side of the arc tube 1 in the figure is integrally formed by firing the closing body 5 to the narrow tube portion (indicated by 3b).
Although the thin tube portion 3b and the closing body 5 are shown as separate members in the drawings for easy understanding, they are substantially fired and integrated with each other.

At the left end of the arc tube 1 in the drawing,
Similar to the first embodiment, the closing body 5 is airtightly bonded to the thin tube portion (indicated by 3a) with the glass adhesive 6. A gap 7 is formed between the thin tube portion 3a and the closing body 5, and excess metal halide is aggregated and accumulated in the gap 7.

Even with such a structure, the excess metal halide accumulated in the gap 7 separates the high-temperature gas in the discharge space from the glass adhesive 6, so that the glass adhesive 6 is prevented from being excessively heated. .

Also in this case, the other thin tube portion 3a sealed with the glass adhesive 6 can be used as an exhaust pipe as in the above-described sealing method. The short arc type metal halide lamp having a structure in which one end is fired and sealed as shown in FIG. 4 is effectively used as a light source of a light projecting device as shown in FIG. 5 as an example of its use. This floodlight device is shown in FIG.
The arc tube 1 has a structure shown in FIG. 1 and a reflector (reflector) 20 that reflects the light emitted from the arc tube 1.

The reflector 20 is made of glass or metal and has a TiO ₂ --Si excellent in reflection property on the inner surface of the rotating curved surface.
A reflective surface 21 made of a vapor deposition film of O ₂ or the like is formed.
The front surface of the reflector 20 is open, and a cylindrical support portion 22 is provided on the top portion on the rear surface side. This cylindrical support 2
The other end of the arc tube 1, that is, the thin tube portion 3a sealed with the glass adhesive 6 and penetrating the other thin tube portion 3a, penetrates the thin tube portion 2a by an adhesive 23 such as insulating cement.
It is fixed to 2. As a result, in the arc tube 1, the lamp axis O ₁ -O ₁ is the central axis of the reflector 20, that is, the optical axis O _2-.
It is attached to the reflector 20 so as to substantially coincide with O ₂ .

The socket 2 is attached to the terminal portions 9 and 9 formed on the outer surfaces of the closing bodies 5 and 5 exposed from the end portion of the arc tube 1.
5, 25 are covered, and these sockets 25, 25
Power supply lines 26, 26 are connected to the. These power supply lines 26, 26 are connected to a power supply, for example, a high frequency power supply 27 that supplies a high frequency of 250 to 400 Hz.

The reflector 20 has one power supply line 26.
An introduction hole 28 is formed to guide the to the back. Further, the arc tube 1 penetrating the cylindrical support portion 22 of the reflector 1
A heat radiation fin 29 is attached to the thin tube portion 3a on one end side as a heat radiation means. This radiation fin 29
The heat of the thin tube portion 3a is released, and as a result, the temperature rise of the glass adhesive 6 in the thin tube portion 3a is prevented.

In the case of the light projecting device having such a structure, when the arc tube 1 is turned on, a part of the light emitted from the arc tube 1 is reflected by the reflecting surface 21 of the reflector 20 and moves forward. The remaining light goes directly to the front of the reflector 20.
Therefore, the light emitted from the arc tube 1 is totally reflected by the reflector 2.
It goes to the front of 0 and irradiates the front.

In this case, the thin tube portion 3b of the arc tube 1 arranged on the front side of the reflector 20 receives infrared rays including direct light and reflected light, and therefore has a high temperature. However, since the thin tube portion 3b is formed by integrally firing and closing the closing body 5,
There is no heat deterioration, that is, since no glass adhesive is used, there is no fear of adhesion failure due to excessive heating of the glass adhesive.

On the other hand, since the thin tube portion 3a of the arc tube 1 arranged on the back side of the reflector 20 does not receive the light emitted from the arc tube 1, the temperature rise is small. In addition, the thin tube portion 3
The heat of a is reflected by the adhesive 23 such as insulating cement or the like in the reflector 20.
It is released to the cylindrical support portion 22. Furthermore, the thin tube portion 3a
The radiating fins 29 attached to radiate the heat of the thin tube portion 3a, thus preventing the temperature of the thin tube portion 3a from rising.

As a result, the coldest portion during lighting is the thin tube portion 3a.
It is formed actively in the inner gap portion 7, and the surplus enclosing chemical, that is, the metal halide is aggregated in this gap portion 7.

From this fact, the glass adhesive 6 is applied to the gap 7
The glass halide 6 is prevented from being excessively heated because it is isolated from the high temperature gas in the discharge space by the metal halide accumulated in the glass. Then, in this case, the thin tube portion 3a does not receive the light emitted from the arc tube 1, the heat of the thin tube portion 3a is released to the reflector 20 by the adhesive 23 such as insulating cement, and the heat radiation fin 29 has the thin tube portion. Since the temperature rise of the thin tube portion 3a is originally prevented by the action of releasing the heat of 3a, the temperature rise of the glass adhesive 6 is also prevented, so that the glass adhesive 6 is thermally deteriorated or chemically deteriorated. Never.

Further, in each of the above-mentioned embodiments, the case where the arc tube 1 has a shape in which the bulging portion 2 is formed at the central portion and the thin tube portions 3 and 3 are integrally formed at both ends has been described.
The shape of the arc tube may be a cylindrical tube shape having substantially the same size along the length direction, as in the fifth embodiment shown in FIG. In the case of FIG. 6, as the closing bodies 5 and 5, the whole is made of tungsten W and alumina (Al ₂ O ₃ ).
An example of a conductive sintered body obtained by mixing the powder of 1. The description of other structures is omitted by using the same numbers as in FIG.

In the above embodiment, the case of the metal halide lamp has been described, but the present invention is not limited to this and may be applied to a high pressure sodium lamp. That is,
High-pressure sodium lamps have conventionally used translucent ceramics as arc tube materials, so the present invention is applicable. Further, the electrodes may be composed of an anode and a cathode which are provided for direct current lighting.

[0060]

As described above, according to the present invention, during lighting, the gap formed between the inner surface of the arc tube end portion and the closing body and the outer surface becomes the coldest portion, and the surplus light emitting metal is present there. Are aggregated and accumulated, so that the aggregated luminescent metal prevents contact between the glass adhesive and the high-temperature gas on the discharge space side. Therefore, the temperature of the glass adhesive is prevented from rising due to the heat of the high temperature gas, and excessive heating of the glass adhesive is prevented. As a result, melting and chemical reaction of the glass adhesive are prevented, reliable sealing is maintained, and life characteristics are improved.

[Brief description of drawings]

1 shows an arc tube of a short arc type metal halide lamp showing a first embodiment of the present invention, FIG. 1 (A) is an overall sectional view, and FIG. 1 (B) is an enlarged sectional view of one thin tube portion,
(C) The figure is a cross section of the thin tube portion.

FIG. 2 is an enlarged sectional view of one thin tube portion showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a thin tube portion showing a third embodiment of the present invention.

FIG. 4 is a sectional view of an entire arc tube of a short arc type metal halide lamp showing a fourth embodiment of the present invention.

5 is a cross-sectional view of a light projecting device configured by incorporating the arc tube of FIG. 4 in a reflector.

FIG. 6 is a sectional view of an arc tube of a metal halide lamp showing a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Arc tube 2 ... Expansion part 3 ... Narrow tube part 5 ... Closure body 6 ... Glass adhesive 7 ... Gap part 8 ... Lead wire part 9 ... Terminal 10 ... Electrode 20 ... Reflector 21 ... Reflection surface 29 ... Radiating fin 70 , 71 ... Groove

Claims (8)

[Claims] 1. An occluding body is hermetically bonded to an opening end of an arc tube made of a translucent ceramic with a glass adhesive, and the occluding body has a conductive means for conducting the inside and outside of the arc tube. A ceramic discharge lamp in which an electrode connected to the conductive means is attached to an inner end portion of a closing body, and a light emitting metal and a rare gas which are in excess of an amount evaporated during lighting are enclosed in the arc tube. A ceramic discharge lamp characterized in that, between the surface, the closing body and the outer surface, a gap portion is formed which communicates with the discharge space and collects excess luminescent metal. 2. The ceramic discharge lamp according to claim 1, wherein the gap has a size such that an excessive amount of aggregated luminescent metal stays due to a capillary phenomenon. 3. The gap portion has at least one groove shape extending in the axial direction formed between the inner surface of the arc tube and the outer surface of the closing body. Item 2. A ceramic discharge lamp according to item 2. 4. The arc tube is provided with a thin tube portion at an end portion of a bulging portion, and the closing body is joined to an opening end portion of the thin tube portion via a glass adhesive, and an inner end portion of the closing body. Is characterized in that the thin tube portion has a length substantially equal to the position where the thin tube portion continues to the bulging portion, and the gap portion is formed between the outer surface of the closing body and the inner surface of the thin tube portion. A ceramic discharge lamp according to any one of claims 1 to 3. 5. The ceramic according to any one of claims 1 to 4, wherein a heat radiating means is provided at an end of the arc tube in which the closing body is sealed with the glass adhesive. Discharge lamp. 6. The ceramic discharge lamp according to claim 1, wherein the light emitting metal is a metal halide. 7. A ceramic discharge lamp according to any one of claims 1 to 6, and a reflector for housing the discharge lamp and reflecting light emitted from the discharge lamp. And a floodlighting device. 8. A predetermined amount of luminescent metal is supplied from an open end of an arc tube made of translucent ceramic, and an open end of the arc tube has a conductive part for conducting the inside and outside of the arc tube in advance. By inserting a closing body formed by joining electrodes to the end portion of the arc tube, a gap is formed between the inner surface of the end portion of the arc tube and the closing body. A method of manufacturing a ceramic discharge lamp, characterized in that the inside of the arc tube is changed to an atmosphere of a rare gas through the opening end, and the opening end of the arc tube and the closing body are joined by a molten glass adhesive.