JPS6228045Y2 - - 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.

1 and 2 are longitudinal cross-sectional views 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 microwave oscillator made of a magnetron, and 2 is a magnetron antenna. , 3 is a waveguide that guides the microwave waves from the microwave oscillator 1, and 4 is a cavity wall whose inner wall shape is rotationally symmetrical, and is made of aluminum or the like so that it can also be used as a light reflecting surface. It has a mirror finish. 5 is a microwave power supply port provided at the joint between the cavity wall 4 and the waveguide 3; 6 is a spherical electrodeless discharge lamp containing at least mercury and a rare gas for starting aid such as argon; It is enclosed. 7
is a fan for cooling the magnetron 1 and the discharge lamp 6; 8 is a vent provided in a part of the waveguide 3; 9 is a mesh plate that covers the front surface of the cavity wall 4; It constitutes a wave cavity 4. 10
1 is a box that covers the magnetron 1, waveguide 3, cavity 41, etc., and 11 is a support rod that supports the discharge lamp 6.

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 is transmitted to the power supply port 5.
is radiated into the cavity 41 through the microwave to form a microwave electromagnetic field within the cavity 41. Due to this microwave electromagnetic field, the starting assisting rare gas in the discharge lamp 6 is discharged, the inner wall of the discharge lamp is heated, metals such as mercury in the tube are evaporated and gasified, and the discharge is a discharge of metal gas. Move to. 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 lamp 6, the rear surface of the cavity wall 4 is used as a reflector,
The front surface is composed of a metal mesh plate 9 that blocks microwaves but transmits light, so that light is emitted only in the forward direction. On the other hand, since the magnetron 1 and discharge lamp 6 need to be cooled during operation, the magnetron 1 is cooled by a cooling fan 7, and this cooling air passes through the vent 8, the waveguide 3, and the power supply port 5 to cool the lamp 6. After that, the air is exhausted from the mesh plate 9.

However, in the microwave discharge light source device configured in this way, as shown by diagonal lines in FIG. The light hitting the waveguide 3
The light leaks inward and does not become effective light to the front, but instead becomes ineffective light. The ratio of invalid light to the total emitted light of the discharge lamp 6 is proportional to the solid angle of the power supply port 5 seen from the discharge lamp 6, so the closer the discharge lamp 6 is to the power supply port 5, the larger this ratio becomes. This has the disadvantage that the amount of light that can be extracted is reduced.

For example, it is usually used to mount a 2450MHz magnetron 1. When using a rectangular waveguide 3 with a cross section of 95.4 mm x 54.6 mm, the shape of the feed port 5 is 60 mm x
It was 20 mm square, and the ratio of the solid angle of the feed port to the total solid angle as seen from the discharge lamp 1, that is, the ratio of invalid light to the total emitted light, reached 10%.

This idea was made in view of the above points, and it guides microwaves from a microwave oscillator into a microwave cavity through a waveguide, and a device installed inside the microwave cavity. In a microwave discharge light source device for lighting an electrode discharge lamp, the microwave power supply port provided at the junction of the waveguide and the microwave cavity is covered with a power supply port cover made of a dielectric material to prevent light from the discharge lamp. The purpose of this is to effectively utilize the light irradiated to the power supply port to reduce the proportion of ineffective light.

An embodiment of this invention will be described below based on FIG. 3. In the figure, reference numeral 51 is a power feed port cover made of a dielectric material such as white ceramic and is provided to cover the power feed port 5, and 81 is a waveguide 3. and an air outlet consisting of a small hole provided at the joint of the cavity wall 4,
82 is an air collection hood for efficiently blowing out cooling air from the air outlet 81, and the waveguide 3
It is constructed from a thin dielectric material to minimize disturbance of the electromagnetic field inside. Further, the discharge lamp 6 is supported by a support rod 11 inserted into a cut-off pipe 42 provided to prevent microwaves from leaking to the outside, similar to those shown in FIGS. 1 and 2.

In the microwave discharge light source device configured in this way, the microwave oscillated from the microwave oscillator 1 and propagated within the waveguide 3 passes through the dielectric feed port cover 51 in the same manner as when the feed port cover 51 is not provided. is radiated into the microwave cavity 41 to form a microwave electromagnetic field within the cavity 41. This microwave electromagnetic field causes the electrodeless discharge lamp 6 to light up, similar to the one shown in FIG. The effective light emitted from the metal mesh plate 7 to the outside includes the light emitted directly from the discharge lamp 6 to the outside through the mesh plate 9, and the light emitted from the cavity wall 4 as shown by A1 in FIG.
Since the cavity wall 4 is mirror-finished, most of the incident light is reflected, or specularly reflected, in a direction that follows the law of light reflection, as shown by B1, and some of it is specularly reflected, as shown by B2. The light that is scattered and exits from the mesh plate 7 as shown in FIG. It is the sum total of Therefore, the light incident on the power feed port 5, which was the cause of 10% of the ineffective light shown in FIGS. 1 and 2, can now be effectively utilized by the power feed port cover 51.

On the other hand, the discharge lamp 6 is cooled by flowing cooling air by the cooling fan 7 through the vent 8, the waveguide 3, and the air outlet 82. The size of the air outlet 82 is determined by the power supply. Since the air outlet 82 may be very small compared to the size of the opening 5, there is almost no loss of light due to the air outlet 82.

In the above embodiment, the feed port cover 51 is made of white ceramic dielectric, but the portion of the feed port cover 51 that is exposed to light, that is, the surface on the microwave cavity side, has a high light absorption rate. It may be constructed of a dielectric covered with a small amount of white dielectric, for example, magnesium oxide; in this case, the power supply port cover 51
Since the loss of light in the metal nut plate 7 is almost eliminated, almost all of the 10% of the ineffective light shown in FIG.

Further, in the above embodiment, the air outlet 8
1 and an air collection hood 82 are provided at the joint between the waveguide 3 and the cavity wall 4, but as shown in FIG. It may be provided in the trunk wall 4, or a part of the power supply port 5 may be used as an air outlet 81 as shown in FIG. For example, support rod 1
1 may be used to cool the discharge lamp 6.

In addition, the space on the waveguide side and the cavity side can be separated by the feed port cover 51, and by injecting nitrogen or the like from the air outlet 81 to create a nitrogen atmosphere inside the cavity, the vacuum ultraviolet rays emitted from the discharge lamp 6 can be removed. It can also be a device that uses light.

As mentioned above, this invention consists of a microwave oscillator, a waveguide that guides the microwaves oscillated by the microwave oscillator, power is supplied to the waveguide through a power supply port, and at least a portion of the waveguide blocks the microwaves. In a microwave discharge light source device comprising a microwave cavity having a light-transmitting member and an electrodeless discharge lamp disposed within the cavity, a power supply of a dielectric material that blocks part or all of the power supply port. Since the lid is provided, the light that enters the feed port from the discharge lamp is reflected to the outside of the microwave cavity by the feed port cover, which has the effect of suppressing the loss of light from the discharge lamp as much as possible.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the configuration of a microwave discharge light source device, Fig. 2 is a front view of the cavity of the microwave discharge light source device of Fig. 1, and Fig. 3 is an embodiment of this invention. FIG. 4 is a longitudinal sectional view showing a microwave discharge light source device according to another embodiment of the invention; FIG.
The figure is a sectional view of a main part showing a microwave discharge light source device according to still another embodiment. In the figure, 1 is a microwave oscillator, 3 is a waveguide, 41 is a cavity, 5 is a feeding port, 51 is a feeding port,
6 is a discharge lamp. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A microwave oscillator, a waveguide that guides the microwaves oscillated by the microwave oscillator, and a waveguide connected to the waveguide through a power supply port to block the microwaves at least partially. A microwave discharge light source device comprising a microwave cavity having a member that transmits light, an electrodeless discharge lamp disposed within the cavity, and a dielectric power supply port cover that partially or completely blocks the power supply port. . (2) The microwave discharge light source device according to claim 1, wherein the power feeding port is made of white ceramic. (3) The microwave discharge light source device according to claim 1, wherein the power feeding port has a surface on the microwave cavity side coated with a white dielectric material. (4) The microwave discharge light source device according to claim 3, characterized in that the white dielectric material is magnesium oxide.