JPH0218560Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a microwave discharge light source device that utilizes microwave discharge.

BACKGROUND ART Recently, light source devices that use high-frequency discharge, particularly microwaves as high-frequency waves, have been attracting attention as light source devices that utilize electric discharge. In conventional light source devices with electrodes, the life of the lamp is determined by the wear and tear of the electrodes, but in light source devices using microwaves, the lamp can be made electrodeless, so the lamp life can be extended.

Furthermore, since there is no heat loss due to electrodes, and the difference in discharge impedance is small between the initial state and the stable state, it is easy to inject power in the initial state even when impedance matching is performed in the stable state. Another characteristic is that the time it takes to reach maximum output is short because the power is concentrated on the lamp tube wall.

FIG. 1 is a longitudinal cross-sectional view showing the configuration of a microwave discharge light source device according to an earlier invention by the present inventors that takes advantage of these features, in which 1 is a magnetron, 2 is a magnetron antenna, 3 is a waveguide, and 4 is a A microwave resonant cavity having a configuration in which a portion of the inner wall forming a reflective surface is formed into a spherical surface 41, a portion following it is formed into a cylindrical surface 42, and the surface serving as a light passing surface is covered with a metal mesh plate 43, 44 is a cylinder. A light anti-reflection treatment layer covering the surface 42, 5 a microwave power feed port provided at the junction of the cavity 4 and the waveguide 3, 6 a spherical discharge lamp, and 61 a tube wall of the discharge lamp 6. A supporting protrusion 7 is formed on the magnetron 1 and the discharge lamp 6.
8 is a vent provided in a part of the waveguide 3; 10 is a box housing the magnetron 1, the waveguide 3, the cavity 4, etc.; 11 is a projection 61;
This is a support rod that supports the discharge lamp 6 by fitting into it.

The operation of this device is as follows. 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 feeds into the feed port 5.
is radiated into the cavity 4 through the microwave, forming a microwave electromagnetic field within the cavity 4. Due to this microwave electromagnetic field, the gas in the discharge lamp 6 is discharged, the inner wall of the discharge lamp is heated, the metal such as mercury in the tube is evaporated and gasified, and the discharge shifts to a discharge of metal gas. At this time, light with a specific emission spectrum depending on the type of metal is generated, and this is used as a light source. In order to effectively utilize the light from the discharge lamp 6, the spherical part of the cavity 4 is used as a reflector, and the front surface is made up of a metal mesh plate 43 that blocks microwaves but transmits light, so that the light is directed only in front. radiate to. On the other hand, since the magnetron 1 and the discharge lamp 6 need to be cooled during operation, they are blown by a cooling fan 7, and this cooling air passes through the vent 8, the waveguide 3, and the power supply port 5, cools the lamp 6, and then cools the mesh. Air is exhausted from the plate 10.

FIG. 2 is a diagram showing the position of the feed port 5 when the cavity 4 is viewed from FIG. 1 with the mesh plate 43 and the box body 10 removed, and the position of the waveguide 3 is shown by a broken line. The spherical surface portion 41 of the inner wall of the cavity 4 is used as a light reflecting surface, so it is finished with a mirror surface using aluminum or the like. In the device configured in this way, if the discharge lamp 6 is located near the center of the spherical portion 41, the light reflected from the spherical surface will be concentrated near the discharge lamp 6, so that the light emitted to the front will become a point. It approximates the light from a light source. However, the spherical part 41
Since the feed port 5 is open in a part of the mirror, the light that hits this part leaks into the waveguide 3 without serving as a reflective surface, and the amount of light that can be taken out to the front is reduced by this amount.

This idea was made to reduce the proportion of invalid light as described above, and the power feed port 5 is connected to the cavity 4.
It is an object of the present invention to provide a microwave discharge light source device in which the proportion of invalid light is small by providing the reflective surface in a portion where no reflective surface is formed.

FIG. 3 is a vertical sectional view showing the configuration of an embodiment of this invention, and FIG. 4 shows the cavity 4 from FIG. 3.
This is a view seen from the front with the mesh plate 43 removed.
A power feeding port 5 is provided in the cylindrical portion 42. Power supply port 5
The position of is closely related to the electromagnetic field modes within the cavity and the electromagnetic field modes within the waveguide.

FIG. 5 is a cross-sectional view of an example of a mode that can be fed when power is fed to the rear surface of the cavity 4 from the end face of the waveguide 3, as shown in FIG. , FIG. 6 is a sectional view taken along the line of FIG. In the figure, E indicates an electric field and H indicates a magnetic field, and as shown in the figure, a mode that easily couples with the mode of the waveguide 3 can be fed. On the other hand, as shown in Figure 3, the cavity 4
An example of a mode in which power can be supplied when power is supplied to the side surface of the waveguide 3 from the end face of the waveguide 3 is shown in FIGS. 7 and 8.
FIG. 7 is a cross-sectional view including the central axis, and FIG. 8 is a cross-sectional view taken along the line of FIG. 7. 7th
As shown in FIG. 8, when power is supplied from the side, a different mode is excited than when power is supplied from the rear. For this reason, the dimensions of the cavities will be of different dimensions.

In other words, when power is supplied from the side, the dimensions of the cavity for the electromagnetic field mode that can be supplied are determined by the cylindrical portion 42.
If we change the length of
The dimensions of the cavity can be determined without changing the dimensions of the cavity, that is, without significantly affecting the light.

In this way, the power supply port can be provided on the side surface that is not used as a reflective surface, and since the entire spherical portion 41 becomes a reflective surface, it is possible to increase the amount of light that can be taken out to the front surface.

As described above, according to the microwave discharge light source device of this invention, the cavity consists of a spherical part constituting a light reflecting surface, a cylindrical part that is subjected to anti-reflection treatment, and an opening in this cylindrical part. The electrodeless discharge lamp is arranged in the center of the spherical part, and the power supply port of the waveguide is provided in the cylindrical part, so that a large amount of light can be taken out to the front. Moreover, the uniformity can be improved.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing the configuration of a conventional microwave discharge light source device, Fig. 2 is a view of the cavity seen from the line in Fig. 1, and Fig. 3 is a longitudinal cross-sectional view showing an embodiment of this invention. Figure 4 is a view of the cavity seen from the line in Figure 3, Figures 5 and 6 are diagrams showing an example of the electromagnetic field inside the cavity of a conventional microwave discharge light source device,
8 and 8 are diagrams showing an example of the electromagnetic field within the cavity of the microwave discharge light source device of this invention. In the figure, 1 is a magnetron, 3 is a waveguide, and 4
is a microwave resonant cavity, 41 is a spherical part, 42 is a cylindrical part, 43 is a mesh plate, 44 is a non-reflection treated layer, 5 is a power feed port, 6 is an electrodeless discharge lamp, 61 is a supporting protrusion, 11 is a support It's a stick. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] A device configured so that microwaves are introduced from a microwave oscillator into a cavity that accommodates a spherical electrodeless discharge lamp using a waveguide, and the light is emitted through a metal mesh plate that forms one side of the cavity. In,
The cavity is composed of a spherical part that constitutes a light reflecting surface, a cylindrical part that is treated with anti-reflection treatment, and a metal mesh plate that covers the opening of this cylindrical part, and the electrodeless discharge lamp is A microwave discharge light source device characterized in that the microwave discharge light source device is arranged at the center of the spherical portion and has a power feeding port of the waveguide provided in the cylindrical portion.