JPH0130254B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave discharge light source device that utilizes light emission by microwave discharge.

FIG. 1 shows a microwave discharge light source device according to the prior art. In the figure, 1 is a microwave oscillator that is a magnetron that generates microwaves, 2 is a magnetron antenna, and 3 is a guide that transmits microwaves. The wave tube 4 consists of a spherical part 5 and a cylindrical part 6 following it, and a cavity wall made of aluminum or the like, and 7 is attached to the flange part 10 of the cavity wall 4 with a holding flange 8 and a holding screw 9. It is a metal mesh plate that blocks microwaves but transmits light.
1. 12 is a power supply port provided at the joint between the waveguide 3 and the cavity wall 4; 13 is a spherical discharge lamp disposed near the center of the spherical portion 5; it is made of quartz glass or the like; It contains rare gases such as mercury, metals such as iron, and halogens such as iodine. 14 is a protrusion provided on a part of the outer wall of the discharge lamp 13, and a part of the discharge lamp support 15 made of a low-loss dielectric material such as quartz glass fits into the flared discharge lamp support part 16. It supports the discharge lamp 13. 17 is a discharge lamp support support part provided in a part of the cavity wall 4 into which the other end of the discharge lamp support 15 is inserted and supports it; 18 is a light emitted from the metal mesh plate 7 to the outside; This is a lens for condensing the light onto an irradiated surface (not shown).

Next, the operation of the microwave discharge light source device configured as described above will be explained. Microwaves generated by the magnetron 1 are radiated into the waveguide 3 through the magnetron antenna 2, and the microwaves propagate through the waveguide 3 and are radiated into the microwave cavity 11 through the feed port 12. The discharge lamp 1 is activated by the microwave electromagnetic field in the microwave cavity 11.
The gas in 3 is discharged, and light with a specific emission spectrum depending on the type of metal enclosed is emitted. If the spherical portion 5 of the cavity wall 4 is made a light reflecting surface, the discharge lamp 13 will be located near the center of the spherical portion 5, so that the reflected light will pass through the vicinity of the discharge lamp 13 again. This reflected light and the direct light of the discharge lamp 13 are applied to the metal mesh plate 7.
radiates outward through the The light emitted outward is condensed onto a necessary irradiated surface by a condenser lens 18 or the like.

In the microwave discharge light source device configured in this manner, the metal mesh plate 7 must suppress the leakage of microwaves to the outside to a level that does not affect the human body, and maintain good light transmittance. There is. For this purpose, when using a magnetron with a frequency of 2450 MHz and an output of 800 W, if the metal mesh pitch is 1.5 mm and the wire width is 0.1 mm, the microwave leakage level outside the metal mesh can be suppressed to 1 mW/cm ² or less. Can be done. Metal mesh plates are usually used to avoid microwave loss due to contact resistance.
Instead of using a mesh of metal wires, one made from a thin metal plate by etching or the like is used. Figure 2 is a partially enlarged plan view of the mesh plate, showing the pitch of the strands 71.
w _p and the maximum line width is w _s . In the above example, the strand 71
Since the cross-sectional shape of is rectangular with a thickness of 0.1 mm and a width of 0.1 mm, the light transmittance is approximately 87%, but the light transmittance in the diagonal direction decreases and the light is transmitted to the outside of the microwave cavity 11. Overall, the light transmission is less than 87%.

In view of the above points, the present invention improves the efficiency of light utilization by providing a metal mesh with a cross-sectional shape that has good light transmittance in an oblique direction.

FIG. 3 is a sectional view of a mesh plate according to an embodiment of the present invention, in which the cross section of the strands 71 of the mesh is triangular. When an oblique light beam shown by an arrow in the figure is incident on the mesh plate 7, the area shown by s in the figure becomes a shadow outside the mesh, and the transmitted light is blocked. Considering the projection of this shadow onto a plane parallel to the mesh plane shown by line BB, the width of the projection of the strand 71 is as shown in Figure 4, which is an enlarged view of Figure 3.
W _sb and pitch are W _pb . When the incident light is projected from the normal to the mesh surface to the angle θ shown in the figure,
Both w _sb and W _pb are the projection width W _sa and pitch of vertically incident light.
W equals _pa . That is, the incident light transmittance does not decrease from the vertical to the angle θ, and the light utilization efficiency does not decrease. On the other hand, microwave leakage is determined by the pitch and maximum width of the mesh strands, so if the pitch and maximum width are the same, there will be no change even if the cross-sectional shape of the strands changes.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention, in which the cross-sectional shape of the wire 71 is shaped like a lens with circular arcs, and in this example, the incident angle of the incident light ranges from the vertical to the angle θ. Even if it changes, there is no change in transmittance.

The processing of the cross-sectional shape of the wire as exemplified above, for example, shown in FIG. 5, involves first forming the cross-sectional shape into a rectangular shape by photo etching, then
Furthermore, it can be molded by adjusting the melting and etching multiple pieces. Further, the triangular shape shown in FIG. 4 is first formed into a rectangular shape and then formed by press working. Note that this molding method can also be applied to the lens-shaped product shown in FIG.

As described above, in the microwave discharge light source device of the present invention, the light utilization efficiency can be improved without increasing microwave leakage.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts of the microwave discharge light source device, Figure 2 is a partially enlarged plan view of the mesh plate, and Figure 3 is a partially enlarged plan view of the mesh plate.
The figure is a partially enlarged cross-sectional view of a mesh plate which is the main part of an embodiment of this invention, FIG. 4 is a partially enlarged view for explaining its light transmittance, and FIG. 5 is another embodiment of this invention. FIG. In the figure, 4 is a cavity wall, 7 is a metal mesh plate, 11 is a microwave cavity, 13 is an electrodeless discharge lamp, and 71 is a wire of the metal mesh plate. In addition,
The same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A microwave cavity that has a power supply port into which microwaves are introduced and is composed of a cavity wall that is open on at least one side, and a metal mesh plate that closes the opening, and a microwave cavity that is disposed within the microwave cavity. The metal mesh plate is formed of an electrically continuous metal plate, and the cross-sectional shape of the mesh wire is , a microwave discharge light source device characterized by having a triangular or oblate convex lens shape.