JPS638579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a microwave discharge light source device, and particularly to support for a discharge lamp thereof.

[Conventional technology]

Recently, high-frequency discharge has been used as a light source device that uses discharge.
Light source devices that use high frequencies, particularly microwaves, are attracting attention. In conventional light source devices with electrodes, the lamp life was determined by the wear and tear of the electrodes.
Light source devices that use microwaves have the advantage of long lamp life because the lamp can be made electrodeless. In addition, there is no heat loss due to the electrodes, and the difference in impedance between the initial state of discharge and the stable state is small, so even if impedance matching is performed in the stable state, power injection in the initial state is easy.
Furthermore, since the discharge power is concentrated on the lamp tube wall, it also has the advantage that the time required to reach the maximum output is shortened.

FIG. 2a is a sectional view showing the structure of a microwave discharge light source device according to the prior art as disclosed in, for example, Japanese Patent Laid-Open No. 56-141165, and FIG. 2b is a sectional view showing the prior art discharge lamp. It is. In the figure,
1 is the magnetron, 2 is the magnetron antenna,
3 is a waveguide, 4 is a microwave cavity whose inner wall is rotationally symmetrical, 40 is a cavity wall, and 5 is provided at the junction between the cavity 4 and the waveguide 3, and the microwave 6 is a spherical electrodeless discharge lamp; 6a is a projection for supporting the discharge lamp formed integrally with the tube body; 7 is a fan; 8 is a part of the waveguide 3; 9 is a metal mesh plate covering the front surface of the cavity 4; 10 is a magnetron 1;
It is a box that covers the waveguide 3, cavity 4, etc.

Next, the operation will be explained. Microwaves generated by the magnetron 1 are radiated into a waveguide 3 through a magnetron antenna 2. This microwave propagates through the waveguide 3 and is radiated into the cavity 4 through the feed port 5, forming a microwave electromagnetic field within the cavity 4. This microwave electromagnetic field causes
The gas in the discharge lamp 6 is discharged and the inner wall of the discharge lamp is heated, and the metal such as mercury sealed in the tube is heated and evaporated, and the discharge shifts to a discharge of metal gas, depending on the type of sealed metal. Light with a specific emission spectrum is emitted. In order to make effective use of this light,
A reflective surface is formed on the rear surface of the cavity 4, and the front surface is covered with a metal mesh plate 9 that does not transmit microwaves but transmits light, so that light is projected only forward. Since the discharge lamp 6 is spherical and can be approximated to a point light source, by making the shape of the reflecting surface of the cavity 4 rotationally symmetrical and setting this shape appropriately, a desired illuminance distribution, for example, uniformity, can be achieved within a circular surface area. Provides illuminance. Note that since the discharge lamp 6 can be placed in a position within the cavity where the distribution of the microwave electromagnetic field is less likely to change, there is little unevenness in light emission, which is advantageous in obtaining a uniform illuminance distribution.

[Problem that the invention seeks to solve]

In the microwave discharge light source device according to this prior art, in order to support the discharge lamp 6 in the cavity, the discharge lamp support member installed on the cavity wall surface is moved to the protrusion 6a.
It was engaged with and supported. At this time, the support member supported the discharge lamp by directly contacting the tube wall of the discharge lamp, which prevented the temperature rise of the tube wall, slowed down the time it took to reach a stable state, and Since the temperature of the tube wall is also low, a large amount of microwave power is required to obtain the desired temperature. Furthermore, when the support member is in contact with the tube wall, light emission is also obstructed to a large extent, which also affects the illuminance distribution.

This invention was made to solve the above-mentioned problems, and it is easy to increase the temperature of the tube wall, keep the microwave power to the necessary minimum, and easily obtain a uniform illuminance distribution. This is how it was done.

[Means for solving problems]

A microwave cavity, which has a power feeding port through which microwaves are introduced, forms an inner wall, and is composed of a cavity wall having an opening, and a metal mesh plate that closes the opening.
A spherical electrodeless discharge lamp disposed within the cavity and enclosing a metal that is heated and evaporated by electric discharge; a protrusion provided on the tube wall of the discharge lamp in which a metal rod is embedded; A support member is provided to support the protrusion so as not to contact the tube wall of the discharge lamp, and to be held in a portion of the cavity wall other than the power supply port to support the discharge lamp.

[Effect]

In the discharge lamp according to the present invention, heat is not directly removed from the tube wall of the discharge lamp by the support member, and the temperature rise of the tube wall is not significantly hindered.
Furthermore, the proportion of light emitted from the discharge lamp being blocked near the tube wall is small.

〔Example〕

FIG. 1 is an enlarged sectional view of a main part of a microwave discharge light source device according to an embodiment of the present invention,
is a discharge lamp support member formed of a low-loss dielectric material such as quartz glass, which is attached near the microwave power supply port 5 of the microwave cavity 4, and has a screw hole 14a in which a screw is formed. Reference numeral 6a denotes a support protrusion formed integrally with the tube body of the discharge lamp 6, which is a metallic discharge starting auxiliary body that concentrates the microwave electromagnetic field before starting the discharge inside and facilitates the starting of the discharge. 13 are buried. A screw 6b is formed on the outer surface to be screwed into the screw hole 14a of the support member 14, and the discharge lamp 6 is fixed by screwing the protrusion 6a into the screw hole 14a of the support member 14.

Even in the microwave discharge light source device configured in this way, the gas in the discharge lamp 6 is discharged and discharged by the microwaves radiated into the cavity 4 through the power supply port 5, as in the prior art device. Emits light. At the time of starting the discharge, the microwave electromagnetic field is concentrated by the metallic discharge starting auxiliary body 13, and becomes a strong microwave electromagnetic field near the discharge lamp 6. Therefore, it is easy to start discharging the gas in the discharge lamp 6. Once the discharge starts, the inner wall of the discharge lamp is heated, and the metal such as mercury sealed in the tube is heated and vaporized, and the discharge shifts to a stable state. When the inner wall of the discharge lamp is heated, heat escapes from the outer wall through the tube wall into the outside air or from the projection 6a to the support member 14. However, the total amount of heat is small because it escapes from the outer wall into the outside air by air heat transfer, and is almost uniform over the entire circumference. Furthermore, since the heat escapes from the protrusion 6a by heat conduction, the amount of heat per unit area is greater than if it escapes from the outer wall by heat transfer. However, since the protrusion 6a is thin, the total amount of heat that escapes is small. In particular, when the support member 14 is in direct contact with the outer wall of the discharge lamp, as in the prior art, this support member 1
Since heat also escapes from No. 4 through heat conduction, the total amount of heat that escapes is large, whereas the one of the present invention has a small amount of total heat that escapes. Less heat escapes,
This means that the temperature of the inner wall of the discharge lamp 6 can be quickly raised with less microwave power, the time required to reach a stable state can be shortened, and the desired temperature can be achieved in a stable state. Further, although the discharge of the discharge lamp 6 normally occurs in a portion close to the tube wall, in a portion where the temperature of the tube wall is low, the discharge moves away from the tube wall toward the center. In the device of this invention, the temperature of the tube wall is lowered at the portion where the protrusion 6a protrudes, but since the protrusion 6a is thin, the area of the lower temperature portion is small, and the influence on the discharge is small. Therefore, the influence on the illuminance distribution is also small. Furthermore, since the support member 14 is not in direct contact with the tube wall of the discharge lamp 6, the amount of light emitted from the inside of the discharge lamp 6 to the outside is obstructed by the support member 14 is small, resulting in a radiation distribution that is close to uniform radiation. Become. Therefore, it is easy to obtain a uniform illuminance distribution.

On the other hand, in this embodiment, since the protrusion 6a is oriented in only one direction, the direct emitted light from the discharge lamp 6 and the reflected light from the reflective surface of the inner wall of the cavity 4 are affected by the protrusion and the supporting member. There are few areas and it is easy to obtain a uniform illuminance distribution.

〔Effect of the invention〕

Even if there is only one protrusion 6a provided on the tube wall of the discharge lamp, the protrusion 6a can be sufficiently reinforced because the metal rod 13 is embedded.

(ii) On the other hand, the metal rod 13 acts as a discharge starting auxiliary body, and the microwave electromagnetic field is concentrated at the time of discharge starting, thereby facilitating the discharge starting of the gas in the discharge lamp 6.

(iii) By embedding one metal rod 13 in the protrusion 6a, it is mechanically reinforced as described above and electrically it is easy to start the discharge, which makes it possible to create an excellent microwave with a simple structure. A discharge light source device can be obtained.

(iv) Since the supporting member of the discharge lamp does not cover the power supply port, microwaves are easily radiated into the cavity from the power supply port before the discharge lamp lights up, and a microwave electromagnetic field is formed in the discharge lamp portion. This has the effect of making it easier to start the discharge.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of essential parts of a microwave discharge light source device according to an embodiment of the present invention, FIG. 2a is a cross-sectional configuration diagram showing the configuration of a microwave discharge light source device according to the prior art, and FIG. 1 is a cross-sectional view of a prior art discharge lamp; FIG. In the figure, 4 is a microwave cavity, 5 is a power supply port, 6 is a discharge lamp, 6a is a projection, 9 is a metal mesh plate, and 14 is a support member. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A microwave cavity that has a feeding port through which microwaves are introduced, has a reflective surface formed on its inner wall, is composed of a cavity wall that has an opening, and a metal mesh plate that closes the opening; A spherical electrodeless discharge lamp that is disposed in a tube and is filled with metal that is heated and evaporated by electric discharge; a protrusion that is provided on the tube wall of this discharge lamp and has a metal rod embedded therein; A microwave discharge light source device comprising: a support member that supports the protrusion so as not to contact the tube wall, and is held in a portion of the cavity wall other than the power supply port to support the discharge lamp.