JPH11162412A - Short arc lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently transfer locally stored heat in the vicinity of the center hole along which an anode is formed to a block-shaped second power supply member with a plate-shaped heat transfer member by interposing the plate-shaped heat transfer member having higher heat conductivity than the second power supply member between a lamp main body base end part and the second power supply member for supporting the anode. SOLUTION: By lighting a lamp, temperature of an anode 22 is raised, and since a lamp main body 1 is made of alumina having low heat conductivity, the vicinity of the center hole 11 of the lamp main body 1 near to the anode 22 becomes higher temperature than other part. Since a heat transfer member 9 having high heat conductivity is bonded to the base end part 1b of the lamp main body 1, heat in the vicinity of the center hole 11 is transferred from the central part of the heat transfer member 9 made of a high heat conductive metal to the diameter direction, furthermore transferred to a block-shaped second power supply member 3 of the base end part of the lamp main body 1, temperature gradient in the diameter direction of the second power supply member 3 is decreased, heat is wholly transferred, and heat is efficiently radiated from the edge of the second power supply member 3 to prevent heat storage in the vicinity of the center hole 11. Deterioration or color change caused by chemical change of a metal deposit film on a reflecting surface 1a is prevented, and drop in reflectance can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short arc lamp integrated with a reflection surface in which a reflection surface is formed on a lamp body forming a discharge space.

[0002]

2. Description of the Related Art A lamp body which forms a discharge space in which a pair of electrodes are disposed is made of ceramic which is an opaque insulating material, and a concave shape such as an elliptical or parabolic cross section is formed inside the lamp body. There is known a short arc lamp in which a reflection surface is formed and an opening of the reflection surface of a lamp body, which is a light extraction portion, is covered with a light transmitting material. Such a short arc lamp integrated with a reflecting surface does not need to be combined with a reflecting mirror, and thus has the advantage of reducing the size of the light source device.
Because it is easy to handle, it is used in fields such as projectors and spectrometers that use parallel light from a powerful point light source, and in fields where a point light source is condensed into a small area and illuminated or heated through an optical fiber. in use. Such a short arc lamp is disclosed in, for example, Japanese Patent Publication No. 54-37436.
And Japanese Patent Publication No. 7-57065.

FIG. 2 shows a conventional short arc lamp integrated with a reflecting surface. The brief arc lamp is briefly described below. A concave discharge space D formed inside a lamp body 1 made of an insulating member is described.
A cathode 21 and an anode 22 are disposed opposite each other, and a reflection surface 1a is formed on the inner surface of the discharge space D. A block-shaped second power supply member 3 is attached to the base end surface 1b of the lamp body 1, and an anode 22 is brazed and held on the second power supply member 3. The anode 22 projects into the discharge space D from the central hole 11 on the base end side of the lamp body 1. On the other hand, the cathode 21 is supported by the conductive electrode support member 5, and the conductive electrode support member 5 is connected to the ring-shaped first power supply member 4 fixed to the opening of the lamp body 1. When the first power supply member 4 and the second power supply member 3 are energized, a discharge occurs between the cathode 21 and the anode 22 to light up.

[0004]

SUMMARY OF THE INVENTION A cathode 21 and an anode 22
Is disposed at the focal position of the reflecting surface 1a having an elliptical or parabolic cross section, so that the anode 22 is located near the center hole 11 on the base end side of the lamp body 1. When the lamp is turned on, the temperature of the anode 22 becomes extremely high. Therefore, the lamp body 1 is strongly heated in the vicinity of the center hole 11, but the lamp body 1 is formed of ceramics, so that the heat conductivity is low.
Difficult to spread inside. Therefore, this heat is generated by the lamp body 1
Is transmitted to the second power supply member 3 attached to the base end face 1b.

When the anode 22, which becomes extremely hot during lighting, is brazed to the second power supply member 3, it is necessary to use a copper brazing material having a high melting point. Therefore,
The second power supply member 3 is also formed of an iron-based metal whose heat-resistant temperature is higher than the melting point of the copper brazing material. However, iron-based metals do not have very high thermal conductivity. Therefore, heat conducted from the vicinity of the center hole 11 of the lamp body 1 to the central portion of the second power supply member 3 is not easily diffused in the radial direction, and the heat does not diffuse to the entire second power supply member 3. That is, the heat dissipation effect of the second power supply member 3 is low.

For this reason, heat is accumulated especially in the vicinity of the center hole 11 of the lamp body 1, and the reflection surface in this portion becomes high in temperature. Therefore, when the lamp is lit for a long time, the deposited film of silver or aluminum formed on the reflective surface may cause a chemical change to be a diffused surface, or a discoloration may cause a problem that the reflectance is reduced due to discoloration. was there. In addition, when the cooling is insufficient, large heat is locally accumulated in the lamp body 1 formed of ceramics, causing strong thermal distortion, and the lamp body 1 may be broken.

Accordingly, an object of the present invention is to provide a short arc lamp integrated with a reflection surface which does not cause a decrease in reflectance or breakage of the lamp body even when the lamp is operated for a long time.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a lamp body comprising an insulating member and having a concave discharge space having a reflective surface therein, and a reflective surface in the discharge space. A ring-shaped first electrode connected to a cathode and an anode opposed to each other with a predetermined interval at a focal position thereof, and a conductive electrode supporting member fixed to an opening of a reflecting surface of the lamp body and supporting the cathode; In a short arc lamp comprising a power supply member and a block-shaped second power supply member which is disposed at a base end opposite to the opening of the lamp body and supports the anode, a base end surface of the lamp body and a second power supply are provided. A plate-like heat transfer member having a higher thermal conductivity than the second power supply member is interposed between the members.

[0009]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of the short arc lamp of the present invention. In FIG. 1, a lamp body 1 is made of alumina as an insulating member, and is a columnar body having an outer diameter of about 60 mm. Inside the lamp body 1, a curved reflecting surface 1a is provided.
Are formed. The cross-sectional shape of the reflecting surface 1a is elliptical or parabolic so as to obtain a light output with high directivity. In this example, the reflecting surface 1a is elliptical. Then, in order to increase the reflection efficiency, a metal such as silver or aluminum is deposited on the reflection surface 1a to be a mirror surface. A dielectric multilayer film may be provided instead of the metal deposition film.

The inside of the reflecting surface 1a is a concave discharge space D, in which a cathode 21 and an anode 22 are opposed to each other with an interval of 1 to 2 mm, and the center thereof is the focal point of the reflecting surface 1a. It is located in. Therefore, the light output is extracted as parallel light. The cathode 21 and the anode 22 are made of tungsten, and the tip of the cathode 21 has a taper angle of 30 ° to 50 ° to improve electron emission.

At the opening of the reflecting surface 1a of the lamp body 1, a ring-shaped first power supply member 4 made of Kovar is provided, and a cylindrical fixing member 7 also made of Kovar having a thickness of about 1 mm and a length of about 10 mm. Installed by. The window member 6 is fitted and fixed in the central opening of the first power supply member 4. The window member 6 is made of sapphire that transmits visible light and has a coefficient of thermal expansion close to that of Kovar, which is a material of the first power supply member 4. Thus, the opening of the reflection surface 1 a is sealed by the first power supply member 4 and the window member 6.

The conductive electrode supporting member 5 has a width of 5.0 to 5.0.
It is made of a molybdenum plate having a thickness of 7.0 mm and a thickness of 0.4 to 0.8 mm, and its base end is fitted and fixed in a groove formed in the first power supply member 4. The base end of the cathode 21 is welded to the front end of the conductive electrode support member 5 extending in the radial direction of the first power supply member 4. Note that the conductive electrode support member 5 does not block the reflected light from the reflection surface 1a.
It is arranged so that the short side direction is parallel to the lamp axis.

A block-shaped second end is provided at the base end of the lamp body 1.
The power supply member 3 is attached by a fixing member 8. The anode 22 projects into the discharge space D from the central hole 11 on the base end side of the lamp body 1. The anode 22, which becomes hot when turned on, is inserted into the center hole of the second power supply member 3 and brazed to the second power supply member 3 with a copper brazing material having a high melting point. The member 3 is formed of an iron-based metal whose heat-resistant temperature is higher than the melting point of the copper brazing material. A plate-shaped heat transfer member 9 is interposed between the base end surface 1b of the lamp body 1 and the second power supply member 3 in a state of being in close contact with both. The heat transfer member 9 is made of a metal having good heat conductivity, for example, a copper-based metal.

An exhaust hole 31 is formed in the second power supply member 3, and the inside of the discharge space D is exhausted from the exhaust hole 31 and filled with an inert gas such as xenon at a pressure of, for example, several tens of atmospheres. The exhaust hole 31 is sealed.

Such a short arc lamp is, for example,
The rated current is 20 A and the power consumption is 300 W.
When this short arc lamp is turned on, the anode 2
2 becomes extremely hot. Since the lamp body 1 is formed of alumina having a low thermal conductivity, the temperature near the center hole 11 of the lamp body 1 near the anode 22 becomes considerably higher than other parts.

However, since the heat transfer member 9 having good heat conductivity is in close contact with the base end surface 1b of the lamp body 1, heat near the center hole 11 of the lamp body 1 is conducted to the central portion of the heat transfer member 9. Then, the heat is quickly conducted in the radial direction of the heat transfer member 9, and the heat is transmitted from the heat transfer member 9 to the second power supply member 3. Therefore, the radial temperature gradient of the second power supply member 3 is reduced.
That is, heat can be entirely conducted to the second power supply member 3, and the heat conducted to the second power supply member 3 is extremely efficiently dissipated from the end face of the second power supply member 3. Therefore, heat does not excessively accumulate near the center hole 11 of the lamp body 1.
For this reason, the metal deposition film formed on the reflection surface 1a does not undergo a chemical change to form a diffusion surface or discoloration, thereby preventing a decrease in reflectance. Further, the lamp body 1 does not generate heat distortion due to locally large accumulated heat, and can prevent the lamp body 1 from breaking.

[0017]

As described above, according to the present invention, the second power supply member is provided between the base end face of the lamp body made of an insulating material having a low thermal conductivity and the second power supply member having a relatively low thermal conductivity. Since the plate-shaped heat transfer member having high thermal conductivity is interposed, the heat locally accumulated near the center hole where the anode of the lamp body comes out is efficiently applied to the entire second power supply member by the plate-shaped heat transfer member. The heat can be transmitted well, and the vicinity of the center hole where the anode of the lamp body projects can be efficiently cooled. Therefore, even if the lamp is turned on for a long time, it is possible to provide a short arc lamp in which the reflectance is not reduced and the lamp body is not broken.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lamp main body 11 Central hole of lamp main body 1a Reflecting surface 1b Base end face of lamp main body 21 Cathode 22 Anode 3 Second power supply member 31 Exhaust hole 4 First power supply member 5 Conductive electrode support member 6 Window member 7 Fixing member 8 Fixing member 9 Heat transfer member D Discharge space

Claims (2)

[Claims] 1. A lamp body comprising an insulating member and having a concave discharge space having a reflective surface formed therein, and a cathode opposed to the focal position of the reflective surface at a predetermined distance in the discharge space. A ring-shaped first electrode fixed to an opening of the reflecting surface of the lamp body and connected to a conductive electrode supporting member for supporting a cathode;
A power supply member, disposed at a base end on the opposite side of the opening of the lamp body,
In a short arc lamp comprising a block-shaped second power supply member supporting an anode, a plate-shaped transmission having a higher thermal conductivity than the second power supply member is provided between a base end surface of the lamp body and the second power supply member. A short arc lamp having a heating member interposed. 2. The second power supply member is made of an iron-based metal,
The short arc lamp according to claim 1, wherein the heat transfer member is made of a copper-based metal.