JPH05343031A - Discharge tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To simplify the structure, to strengthen the mechanical strength, and to prevent dispersion of emission. CONSTITUTION:An inner tube 14 is sealed in an outer tube 15. A counter electrodes 12 are sealed airtightly in the inner tube 14, and a leads 17 is guided out of a protective cylinder part 16 of small diameter of the inner tube 14. The outer tube 15 is formed out of first and second outer tubes 15a, 15b having a large diameter part 19 and a small diameter part 20 respectively. The counter ends formed on the large diameter parts 19 of the first and the second outer tubes 15a and 15b are butted together and a connected part 18 is formed. The protective cylinder part 1 of the inner tube 14 and the leads 17 are supported with the small diameter parts 20 of the first and the second outer tubes 15a, 15b, and the small diameter parts 20 are completely sealed and are cut, while the leads 17 are guided airtight from the small diameter parts to the outside. The small diameter part(s) of the first and/or second outer tubes 15a, 15b also serves as an exhausting tube at the time of evacuating the outer tube 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube having a double tube structure in which an inner tube having an arc portion is enclosed in an outer tube and a method for manufacturing the same.

[0002]

2. Description of the Related Art A discharge tube such as a metal vapor discharge tube is used as a light source device for a liquid crystal projector, for example. These discharge tubes generally have a double-tube structure.The inner tube that forms the arc part by hermetically sealing the opposing electrodes is a cylindrical outer tube that is filled with vacuum or a small amount of rare gas in the vacuum. It is configured by hermetically sealing in. By heat-insulating the inner tube and the outer tube in a vacuum state in this way, the heat storage capacity of the inner tube is increased, and in the case of the same electric rating and the same luminous efficiency as compared with the discharge tube having no outer tube, The volume of the inner tube can be increased. As a result, the dirt and the like due to the sputtered material is reduced per unit area as compared with the discharge tube having no outer tube, and the life of the discharge tube can be extended.

By the way, in the discharge tube of this double tube structure,
The inner tube is inserted from the end of the outer tube, the inner tube is floated and supported inside the outer tube, the end of the outer tube is further sealed, and the lead wire is airtightly led out from this sealing section. .. For this reason,
There is a problem that the structure of the discharge tube becomes complicated and the manufacturing process is troublesome. With respect to these points, various improvements have been made in the past, and applications such as JP-A-61-78044 and JP-A-3-37951 have been filed.

In the invention of Japanese Patent Laid-Open No. 61-78044, an exhaust pipe is introduced inside by hermetically penetrating a sealing portion formed by crushing or the like at the end of the outer tube of the discharge tube. Lock the lead wire drawn from the inner pipe to the tip of the exhaust pipe,
This exhaust pipe supports the weight of the inner pipe. Further, in the invention of Japanese Patent Laid-Open No. 3-37951, the end of the exhaust pipe is projected inside the end of the outer pipe of the discharge tube, and the inner protruding end of the exhaust pipe is made to support the inner pipe through a mount member. It is a structure.

The discharge tubes disclosed in JP-A-61-78044 and JP-A-3-37951 have the drawbacks that the supporting structure of the inner tube is complicated and the strength is weak.

To solve the above drawbacks, for example, FIG.
The discharge tube (unpublished) shown in FIG. 7 is considered. In the discharge tube 1 shown in the figure, an inner tube 4 in which an arc portion 3 is formed by airtightly sealing a counter electrode 2 is sealed inside an outer tube 5,
Sealing portions 6 are formed at both ends of the outer tube 5. Each lead wire 7 connected to the counter electrode 2 is led out from the inner tube 4 in the opposite direction. Further, the lead wire 7 is airtightly inserted through the sealing portion 6 of the outer tube 5 and led out to the outside. Has been done.

In the case of the discharge tube 1, the diameter of the sealing portion 6 for closing the end portion of the outer tube 5 is set to be at least larger than the maximum diameter of the inner tube 3 for inserting the inner tube 3. For this reason, it is very difficult to directly connect the sealing portion 6 to the exhaust base. Even if the sealing portion 6 can be connected, the discharge tube 1 and the exhaust base (Fig. However, there is a problem in that work efficiency is poor when the glass is heated and softened by using a burner because it is separated (not shown).

From this, as shown in FIG. 7, an exhaust pipe 8 is separately provided on the outer peripheral portion of the outer pipe 5, and the exhaust pipe 8 is attached to the exhaust base 9.
And the inside of the outer tube 5 is evacuated. And the outer tube 5
After the inside is evacuated, the root portion of the exhaust pipe 8 is softened by heating and sealed at the position of the dotted line 8a.

[0009]

According to this discharge tube 1, the sealing portion 6 is not provided with an exhaust pipe or the like, and the structure is simple, the size can be reduced, and the strength is improved. Since the exhaust pipe 8 is provided in a place different from 6, the disadvantage is that the number of working steps increases. Also, this discharge tube 1
Then, there is a drawback that the projection 10 is formed after the root portion of the exhaust pipe 8 is heated and softened by the burner and sealed off, and the projection 10 scatters light emission.

The present invention is an improvement over the above-mentioned conventional drawbacks, and an object thereof is to provide a discharge tube having a double tube structure which can be effectively used without scattering light emission, and has a simple structure and strong strength. And

[0011]

DISCLOSURE OF THE INVENTION A discharge tube according to the present invention comprises:
The opposite electrode is hermetically sealed to form an arc portion, and the inner tube with the lead wire of the electrode led out in the opposite direction has a large diameter portion and a small diameter portion, respectively, and the opposite end edges on the large diameter portion side are joined. And a first and a second outer tube in which the inner tube is enclosed and the lead wire is airtightly led out from the small diameter portion.
Further, at least one small-diameter portion of the second outer pipe is configured to also serve as an exhaust pipe when the inside of the outer pipe is evacuated.

The method of manufacturing a discharge tube according to the present invention is
First and second outer tubes having a large diameter portion and a small diameter portion, respectively, from both end directions of the inner tube in which opposite electrodes are hermetically sealed to form an arc portion and lead wires of the electrodes are led out in opposite directions. The opposite end edges on the large diameter side of each other are close to each other, and the lead wires are inserted into the small diameter portions of the first and second outer tubes, and then the opposite end edges are joined to each other, and at least one of the small diameter portions is exhausted It is characterized in that the lead wire is airtightly drawn from the outer tube by using the tube as a tube to evacuate the outer tube and sealing off the small diameter portion.

[0013]

In the discharge tube of the present invention, the opposing edges of the first and second outer tubes are joined together, and the inner tube is housed therein. Lead wires led out from both ends of the inner pipe are inserted into the small diameter parts of the first and second outer pipes, and are led out airtightly from the small diameter parts,
The inner tube is supported inside the outer tube. Also, the first and second
At least one of the small-diameter portions of the outer tube also serves as an exhaust pipe, whereby the inside of the outer tube is evacuated and the small-diameter portion is sealed off.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are a horizontal sectional view and a vertical sectional view of a discharge tube according to an embodiment. 3 to 5 are sectional views showing the manufacturing process of the discharge tube.

1 and 2, the discharge tube 11 is the inner tube 1
4 and an outer pipe 15 accommodating the inner pipe 14 to form a so-called double pipe structure. The inner tube 14 is a luminescent glass tube, in which xenon
Argon and metal / metal halide are enclosed, and the counter electrode 12 made of tungsten or the like is hermetically sealed to form an arc portion 13. A small-diameter protective cylinder portion 16 extends from the arc portion 13 to both ends,
A lead wire 17 that is hermetically inserted through the protective cylinder portion 16 and connected to the electrode 12 is led out to the outside.

The outer tube 15 is a glass tube,
The outer pipe 15a and the second outer pipe 15b are joined to each other by joining the joint portions 18 at the opposite edges. First and second outer tube 15
Each of a and 15b is composed of a large diameter portion 19 and a small diameter portion 20, and the joint portion 18 includes the first and second outer pipes 15a and 15a.
It is formed on the edge of each large-diameter portion 19 of 15b.

The inner pipe 14 is enclosed in the large-diameter portion 19 of the first and second outer pipes 15a and 15b thus joined together with an appropriate vacuum space 21. This vacuum space 2
1 may be filled with a small amount of rare gas to prevent oxidation of the lead wire 17. The protective tube portion 16 of the inner tube 14 is the outer tube 15
The inner pipe 14 is held by the small diameter portion 20. Therefore, the arc portion 13 of the inner tube 14 is held inside the outer tube 15 via the necessary vacuum space 21 by such a support structure.

The lead wire 17 led out from the protective tube portion 16 of the inner tube 14 is further led out to the outside by hermetically inserting the small diameter portion 20 of the outer tube 15. In the case of the embodiment, the small diameter portion 2
0 is the first stage 20a, the second stage 20b, and the third stage 2
It is known to be 0c. The protective tube portion 16 of the inner pipe 14 is inserted into the second stage 20b and is closely supported by the portion indicated by the chain line 22. In addition, the first stage 20a and the inner pipe 1
A small space 21a continuous with the vacuum space 21 is formed between the fourth protection cylinder portion 16 and the protection cylinder portion 16.

As described above, the small-diameter portion 20 of the outer pipe 15 is not only the airtight lead-out portion of the lead wire 17 leading out of the inner pipe 14, but also the support portion of the protective tubular portion 16 of the inner pipe 14. Further, at least one of the small diameter portions 20 also serves as an exhaust pipe when the inside of the outer pipe 15 is evacuated. Therefore, the second step 20b and the third step 20c of the small-diameter portion 20 have a tubular shape when the vacuum is drawn, and are then melted by heating and sealed to have the cross-sectional shapes shown in FIGS. It is transformed. As described above, the evacuation may be performed by using the small diameter portions 20 on both sides of the outer tube 15, or only the small diameter portion 20 on one side may be used. In the latter case, the first
Alternatively, the tip of the small-diameter portion 20 of the second outer tubes 15a and 15b, which is not used for exhaust, may have a bottomed structure that is closed in advance when the glass tube is molded.

Further, the protective tube portion 16 of the inner tube 14 and the outer tube 15
When the glass tube of the small-diameter portion 20 is heated and softened and sealed off, the protective tubular portion 16 and the glass portion of the small-diameter portion 20 are subjected to uneven stress due to thermal expansion and contraction. There is a possibility that cracks may occur or a gap may be formed around the lead-out portion of the lead wire 17, and the degree of vacuum of the inner tube 14 and the outer tube 15 may drop. Therefore, in the present embodiment, the lead wire 17 led out from the inner tube 14 is configured by alternately connecting a plurality of molybdenum wires 17a and molybdenum foil 17b, and further by interposing the molybdenum buffer wire 17c. Especially molybdenum foil 1
The thermal expansion of the small diameter portion 20 is suppressed by 7b, and cracks and the like are not generated in this portion during sealing. The molybdenum buffer wire 17c is for releasing stress caused by heat generated between the inner tube 14 and the outer tube 15 when the discharge tube 11 is turned on.

Next, referring to FIGS. 3 to 5, the discharge tube 1 is described.
The manufacturing process of No. 1 will be described.

In FIG. 3, centering on the inner tube 14 in which the lead wires 17 are led out in opposite directions, the opposite end edges 23 of the first outer tube 15a and the second outer tube 15b from both ends of the inner tube 14 are arranged. , 24 are shown in close proximity. In the figure, the facing end edge 23 of the first outer tube 15a is located on the large diameter portion 19 side, and the end surface 25 of the small diameter portion 20 is closed to have a bottomed shape. On the other hand, in the second outer tube 15b as well, the facing end edge 24 is located on the large diameter portion 19 side, but the large diameter portion 1
Both ends of 9 and the small diameter portion 20 are open. Therefore, the small-diameter portion 20 of the second outer pipe 15b can also serve as an exhaust pipe when the inside of the outer pipe is evacuated.

As described above, the opposing end edges 23 and 24 of the first and second outer pipes 15a and 15b are brought closer to each other with the inner pipe 14 interposed therebetween, and are brought into contact with each other. By heating and softening the contact portion, the first and second outer tubes 15a and 15b can be integrated via the joint portion 18 as shown in FIG. At this time, both ends of the inner pipe 14, that is, the protective cylinder portion 16 is inserted and supported by the small diameter portion 20 of the outer pipe 15, and the lead wire 17 is also inserted in the small diameter portion 20.

In the illustrated case, the first and second outer tubes 15
The positions of the opposite end edges 23 and 24 of the a and 15b are provided at positions slightly offset to the first outer pipe 15a side from the central portion that is the maximum diameter portion of the outer pipe 15. This is because the position of the joint portion 18 is moved away from the center of the arc portion as much as possible to reduce the risk of deterioration of the directivity of light, and the joint portion 18 is displaced from the maximum diameter portion so that the joint area is smaller. This is because the joining is performed and the joining portion 18 is displaced from the central portion of the outer tube 15 so that the strength is not deteriorated even with respect to the stress applied to the outer tube 15.

Therefore, the position of the joint portion 18, that is, the position of the opposite end edges 23, 24 is not limited to the position shown in the drawing, but at least the diameter on one side of the opposite end edges 23, 24 is equal to that of the inner pipe 14. It must be formed larger than the maximum diameter portion. As a result, the inner pipe 14 can be housed inside the outer pipe 15 from the facing end edges 23 and 24.

The maximum diameter portion of the inner pipe 14, that is,
The maximum diameter portion of the arc portion 13 is larger than the inner diameter of the small diameter portion 20 of the outer tube 15. That is, in the case of the present invention, the inner pipe 14 is housed inside the outer pipe 15 not from the end portion but from the opposite end edges 23 and 24 of the first and second outer pipes 15a and 15b. As described above, there is no problem even if the maximum diameter portion of the inner pipe 14 is larger than the small diameter portion 20 of the outer pipe 15. Thus, if the small diameter portion 19 of the outer pipe 15 can be made small regardless of the maximum diameter portion of the inner pipe 14,
The work of crushing and molding the small-diameter portion 20 by heating and softening is easier than the work of sealing the large-diameter portion, and quick and accurate sealing work can be performed.

Next, FIG. 4 shows the first and second outer tubes 15 described above.
The state which joined each opposite end edge 23, 24 of a, 15b is shown, and at this time, the protection cylinder part 16 of the inner pipe 14 and the lead wire 17 are shown.
Is inserted into the small-diameter portion 20 as described above. In this state, the exhaust base 25 is connected to the tip of the small diameter portion 20 of the second outer pipe 15a to evacuate the inside of the outer pipe 15.

After the outer tube 15 is evacuated in this way, the glass portions of the small diameter portions 20 of the first and second outer tubes 15a and 15b are heat-softened and crush-molded as shown in FIG. 15
The inner tube 14 is enclosed inside. At this time, the protective tube portion 16 of the inner pipe 14 is made into the thin portion 2 of the first and second outer pipes 15a and 15b.
0, and the lead wire 17 is embedded in the crushed small-diameter portion 20. Further, at this time, the small-diameter portion 20 may be thermally expanded and contracted by heating and softening, so that cracks and the like may occur in the small-diameter portion 20, but as described above, the lead wire 17 is not the molybdenum wire 17a. Since the molybdenum foil 17b is connected, the small-diameter portion 2
It is possible to prevent the occurrence of cracks at 0 or a gap around the lead wire 17 to lower the degree of vacuum inside the outer tube 15.

After the inner pipe 14 is sealed in the outer pipe 15 in this manner, the small-diameter portions 20 of the first and second outer pipes 15a and 15b are exhausted at the positions indicated by the dotted lines 26 in FIG. Separate from the table 25. As a result, the tips of the lead wires 17 are led out from the ends of the sealed small-diameter portion 20. Through these steps, the discharge tube 11 having the double tube structure shown in FIGS. 1 and 2 is manufactured.

In the above embodiment, the first outer tube 15
Although the end surface 25 of the small-diameter portion 20 of a is configured to have a bottom, the small-diameter portion 20 of the first outer pipe 15a is also formed into the second outer pipe 1.
The small-diameter portion 5b may be opened similarly to the small-diameter portion 20, and the small-diameter portion 20 may also be exhausted (not shown).
Alternatively, only one of the protection cylinder portions 16 of the inner pipe 14 may be supported by the small diameter portion 20 of the outer pipe 15.

[0032]

As described above, according to the discharge tube of the present invention, the inner tube is sealed from the opposite end edges of the first and second outer tubes, so that the inner tube is provided at the end of the outer tube. Even if a small diameter portion smaller than the maximum diameter is formed, there is no problem in enclosing the inner pipe. Therefore, the shape of the outer tube is made to have a large diameter portion and a small diameter portion in accordance with the outer shape of the inner tube, the arc portion of the inner tube is arranged in the large diameter portion, and the lead wire can be led out from the small diameter portion.
Therefore, the outer tube can be made to have the minimum required space between the inner tube and the outer tube, the outer tube can be made as small as possible in comparison with the conventional one, and the discharge tube can be mounted in a space. Is advantageous in terms of.

Further, in the present invention, the small diameter portion of the outer tube is sealed off as described above, and since the diameter of this sealing portion may be smaller than the maximum diameter of the inner tube, the sealing operation is easy. It can be done quickly and accurately. Further, if the diameter of the sealing portion is small, the portion that interferes with the light emitted from the inner tube is reduced accordingly, and the irradiation efficiency when using this discharge tube as a light source device is improved. Further, according to the present invention, the exhaust base can be directly connected to the small-diameter portion to evacuate the inside of the outer tube, so that the number of manufacturing steps is reduced as compared with the case where the exhaust tube is provided separately from the outer tube. And the structure is simple, and the strength is improved accordingly.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a discharge tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of FIG.

FIG. 3 is a cross-sectional view of a first step in manufacturing the discharge tube of the present invention.

FIG. 4 is likewise a sectional view of a second step.

FIG. 5 is likewise a sectional view of a third step.

FIG. 6 is an explanatory diagram of a discharge tube shown as a comparative example of the present invention.

FIG. 7 is an explanatory view showing a mode of evacuating the discharge tube.

[Explanation of symbols]

11 ... Discharge tube, 12 ... Electrode, 13 ... Arc part, 14 ... Inner tube, 15 ... Outer tube, 16 ... Protective tube part, 17 ... Lead wire, 1
8 ... Joined portion, 19 ... Large diameter portion, 20 ... Small diameter portion, 21 ... Vacuum space, 23 ... Opposing edge, 24 ... Opposing edge.

Claims (2)

[Claims] 1. An inner tube in which opposing electrodes are hermetically sealed to form an arc portion, and lead wires of the electrode are led out in opposite directions; and a large diameter portion and a small diameter portion, respectively. First and second parts formed by joining opposite end edges of each other, enclosing the inner tube therein, and leading the lead wire airtightly from the small-diameter portion.
The discharge tube, characterized in that at least one of the first and second outer tubes has a small diameter portion that also serves as an exhaust tube when the inside of the outer tube is evacuated. 2. A first electrode having a large-diameter portion and a small-diameter portion from opposite ends of an inner tube, in which opposite electrodes are hermetically sealed to form an arc portion and lead wires of the electrodes are led out in opposite directions. The large-diameter-side opposing end edges of the second outer pipe are brought close to each other, and the lead wires are inserted into the small-diameter portions of the first and second outer pipes, and the opposing end edges are joined to each other. A method for manufacturing a discharge tube, characterized in that a vacuum is evacuated from the outer tube by making the small-diameter portion also serve as an exhaust tube, and the lead wire is airtightly drawn from the outer tube by sealing off the small-diameter portion. ..