JP4984352B2 - Anti-oxidation structure of high-intensity discharge lamp and high-intensity discharge lamp having the structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oxidation preventing structure for a sealing portion of a high-intensity discharge lamp such as an ultra-high pressure mercury lamp incorporated in various projector apparatuses.
[0002]
[Prior art]
As a high-intensity discharge lamp using a functionally gradient material as a closing body, one disclosed in JP-A-11-312492 is known. The contents of this prior art (particularly FIG. 4) are shown in FIG.
[0003]
That is, the high-intensity discharge lamp 100 is generally used as a shield beam lamp device or the like in combination with the reflector 101. When mounted on the reflector 101, the light emission source of the high-intensity discharge lamp 100, that is, the intermediate positions of the internal electrodes 102 and 102 are made to coincide with the focal position of the reflector 101.
[0004]
[Problems to be solved by the invention]
In order to achieve miniaturization of the projector device, it is essential to miniaturize a lamp unit in which a high-intensity discharge lamp is assembled to a reflector. However, if the lamp unit is simply reduced in size, the angle of light taken in by the reflector is reduced and the amount of light is insufficient.
[0005]
Therefore, in order to compensate for the shortage of light quantity, it is conceivable to make the gap between the internal electrodes 102 and 102 narrower than the current 1.5 mm, and to improve the reflection efficiency by making it closer to an ideal point light source.
[0006]
However, if the gap between the internal electrodes is shortened, the lamp voltage decreases and the current value in the steady state increases, resulting in an increase in electrode friction speed and a shortened life. Therefore, it is conceivable to increase the luminous substance pressure in the lamp in order to increase the lamp voltage. However, the reliability of the seal decreases as the luminescent material pressure in the lamp increases.
[0007]
On the other hand, the lamp unit can be downsized even if the sealing tube portion is shortened. However, it has been found that when the sealing tube portion is shortened, the conductive portion of the functionally gradient material constituting the closing body is oxidized and easily broken.
[0008]
In Japanese Patent Laid-Open No. 11-312492, as shown in FIG. 3, the sealing tube portion 104 formed continuously with the arc tube portion 103 is extended from the closing body 105 and the tip is closed. The evaporation material from the closing body 105 is prevented from leaking to the outside (reflector). However, even if the tip of the sealing tube portion 104 is closed, it is not hermetically sealed, so that the conductive portion of the closing body is oxidized. Even if it can be hermetically sealed, it is oxidized by oxygen remaining in the sealing tube portion 104.
[0009]
Further, as a prior art for preventing the oxidation of the conductive portion of the closing body, there is one disclosed in WO98 / 47169, but this prior art is a portion exposed outside the side tube (sealing tube portion). Is an anti-oxidation structure that covers the surface with an air barrier layer, and is a technique that cannot be applied to the downsizing of the lamp that the present application aims at.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the oxidation prevention structure for a high-intensity discharge lamp according to the present invention has a sealing tube portion integrally provided at both ends of the arc tube portion, and the sealing tube portion is made of a functionally graded material. Is attached so that the insulating part is on the inside and the conductive part is on the outside, and an internal electrode is inserted into this closing body until one end faces the inside of the arc tube and the other end reaches the conductive part. In a high-intensity discharge lamp in which a power supply external electrode is connected to the conductive portion, at least one of the sealing tube portions extends to a position outside the closing body, and the tip portion is sealed, and this sealing is performed. by defining a non-oxidizing atmosphere space inside the sealing tube part, viewed the electrically conductive portion of the closure in a non-oxidizing atmosphere in the space is extraordinary, Mo foil is sealed in the distal sealing portion of the sealing tube portion And a conductive member for connecting the Mo foil and the conductive portion of the closure body. , The conductive member was configured to be connected to the outer surface of the electrically conductive portion of the closure.
[0011]
In order to supply power to the conductive part of the closing body from the outside, for example, a Mo foil is enclosed in the tip sealing part of the sealing tube part, and power is supplied to the conductive part of the closing body via the Mo foil. It is preferable to maintain airtightness.
[0012]
With the above configuration, a miniaturized high-intensity discharge lamp can be obtained. Specifically, a high-intensity discharge lamp is obtained in which the gap between the internal electrodes is less than 1.5 mm, preferably 1.0 mm or less, and the length of at least one sealing tube is less than 25 mm, preferably 20 mm or less.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of an ultra-high pressure mercury lamp as a high-intensity discharge lamp according to the present invention, and FIG. 2 is an overall view of a shielded beam lamp apparatus to which the ultra-high pressure mercury lamp is applied. An ultrahigh pressure mercury lamp 1 is detachably attached to the center of a reflector 20 made of glass.
[0014]
The lamp 1 is formed by integrally molding an arc tube portion 2 for enclosing mercury vapor and left and right sealing tube portions 3 and 4 provided continuously at both ends of the arc tube portion 2 by casting or the like. 3 and 4 are hermetically sealed by the closing bodies 5 and 6.
[0015]
The arc tube portion 2 and the sealing tube portions 3 and 4 are made of high-purity polycrystalline silicon oxide (SiO 2), and the closing bodies 5 and 6 are made of functionally gradient material. The closing bodies 5 and 6 made of a functionally gradient material are mounted such that the insulating portion is on the inner side (arc tube side) and the conductive portion is on the outer side, and the insulating portion is mainly the arc tube portion 2 and the sealing tube. It consists of the material which comprises the parts 3 and 4, and becomes the electroconductive part by gradually increasing the ratio of molybdenum toward the outer side. As a material for the sealing tube portion, a material that can be used as an arc tube such as alumina (Al 2 O 3) or YAG can be appropriately selected in addition to the above-described SiO 2. In this case, the same material is used for the insulating part of the functionally gradient material, or the material having a similar thermal expansion coefficient is used. Further, as the material of the conductive portion, a material such as tungsten can be appropriately selected in addition to molybdenum.
[0016]
A pair of tungsten (W) internal electrodes 7, 8 are inserted into the insulating portions of the closing bodies 5, 6 until reaching the conductive portions, and the internal holes 7, 8 due to the difference in thermal expansion coefficient are inserted into the insertion holes. A cermet is used to prevent the dropout. In this embodiment, the gap between the internal electrodes 7 and 8 is 0.7 mm.
[0017]
Further, the length of the sealing tube portion 3 is 30 mm, the length of the sealing tube portion 4 is 17 mm, and the conductive portion of the closing body 5 has an external portion made of niobium (Nb) or tungsten (W). The electrode 9 is inserted, and the outside thereof is attached to the reflector 20 via the socket 10. The external electrode can be appropriately selected as long as it is an electrically conductive material. In addition to the above material, molybdenum (Mo), nickel (Ni), or an alloy thereof can be used.
[0018]
On the other hand, the front end of the sealing tube portion 4 is sealed in a non-oxidized state to form a non-oxidizing atmosphere space S, and the closed body 6 conductive portion faces the non-oxidizing atmosphere space S. Moreover, Mo (molybdenum) foil 11 is enclosed in the front end sealing portion of the sealing tube portion 4, and the Mo foil 11 and the conductive portion of the closing body 6 are connected by the conductive member 12. 11, an external electrode 13 is connected to achieve electrical continuity with the outside.
[0019]
If power is supplied through the Mo foil 11 in this way, leakage from the sealing can be effectively prevented, and air does not enter the sealing tube portion 4 from the outside, so a non-oxidizing atmosphere Can be maintained, and oxidation of the conductive portion of the closure 6 can be prevented.
[0020]
In the embodiment, an ultra-high pressure mercury lamp has been described as a high-intensity discharge lamp, but the present invention can also be applied to a metal halide lamp, a sodium lamp, or the like.
[0021]
【Effect of the invention】
As described above, according to the present invention, it is possible to obtain a high-intensity discharge lamp having a small size in which the gap between the internal electrodes or the length of the sealing tube portion is shortened and the conductive portion of the closing body is hardly oxidized. Therefore, it is possible to provide a high-intensity discharge lamp that can achieve downsizing of various projectors.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an ultra-high pressure mercury lamp according to the present invention. FIG. 2 is an overall view of a shield beam lamp device to which the ultra-high pressure mercury lamp is applied. Overall view of the device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Super high pressure mercury lamp, 2 ... Light emission tube part, 3, 4 ... Sealing tube part, 5, 6 ... Closure body, 7, 8 ... Internal electrode, 9, 13 ... External electrode, 10 ... Socket, 11 ... Mo Foil, 12 ... conductive member, S ... non-oxidizing atmosphere space.

Claims (3)

Sealing tube portions are integrally provided at both ends of the arc tube portion, and a sealing body made of a functionally gradient material is attached to the sealing tube portion so that the insulating portion is on the inside and the conductive portion is on the outside, In the high-intensity discharge lamp in which an internal electrode is inserted until one end faces the arc tube portion and the other end reaches the conductive portion, and an external electrode for power supply is connected to the conductive portion of the closed body. At least one of the sealing tube portions is extended to a position outside the closing body, and the tip portion is sealed. By this sealing, a non-oxidizing atmosphere space is defined inside the sealing tube portion. A conductive part of the closing body faces in the space, Mo foil is sealed in the tip sealing part of the sealing tube part, and a conductive member for connecting the Mo foil and the conductive part of the closing body is provided. The conductive member is connected to the outer surface of the conductive portion of the closing body. Antioxidant structure of a high intensity discharge lamp, characterized in that. 2. The oxidation preventing structure for a high-intensity discharge lamp according to claim 1 , wherein a distance between the pair of internal electrodes is less than 1.5 mm, and a length of at least one of the sealing tube portions is less than 25 mm. The oxidation prevention structure of a high-intensity discharge lamp. A high-intensity discharge lamp comprising the antioxidant structure according to claim 1.

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