JPS6255859A - Microwave discharge power supply device - Google Patents

Abstract

PURPOSE:To suppress loss of microwave by reflecting the microwave transmitted through a light emission tube by a metal conductor functionable as cavity resonator then leading again to the light emission tube to contribute for light emission. CONSTITUTION:Microwave transmitted through a waveguide 1 to an antenna 4 is radiated through said antenna 4 to the inside face of light emission tube 5. This microwave will excite the rare gas encapsulated in the light emission tube 5 to produce discharge plasma while a portion will transmit through the light emission tube 5 to a metal conductor 61 arranged around said tube 5. Since the metal conductor 61 is forming a resonator 71, the microwave is reflected again to the light emission tube 5 thus to excite the rare gas encapsulated in said tube 5. The light produced from respective discharge plasma will be reflected by the cover 8 or transmit through the opening (mesh) of metal mesh forming the metal conductor 61 and irradiate the outside of the unit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a microwave discharge light source device that uses microwaves to generate discharge plasma in an arc tube to emit light.

[Technical background of the invention and its problems]

In recent years, light source devices using microwaves have attracted attention as light source devices that utilize electric discharge, and some of them have already been put into practical use.

In this light source device using microwaves, since one arc tube can be made electrodeless, problems such as defects due to consumption of the electrode material and blackening of the lamp wall due to evaporation of the electrode can be solved.

FIG. 4 is a sectional view showing an example of the structure of this microwave discharge light source device (Japanese Patent Application No. 59-274625).

The device shown in the figure propagates microwaves emitted from a magnetron 31 through a waveguide 32 and further radiates them to an arc tube 34 by a conductive antenna 33. The guide bar 35 is provided to irradiate the light emitted by the arc tube 34 downward in the figure. The gas enclosed in the arc tube 34K is excited by the microwave and a discharge occurs.

To explain in more detail, most of the microwaves reaching the arc tube 34 are absorbed near the wall of the arc tube 34 close to the antenna 33, and a discharge plasma is generated near the inner surface of the wall of the arc tube 34. In addition, a part of the microwaves not absorbed by the gas sealed inside the second arc tube 34 passes through the pulp of the nine arc tube 34.

As a safety measure to prevent the transmitted microwaves from leaking to the outside of the device, a measure is generally taken to provide a metal net or the like around the arc tube 34 to shield the microwaves. In other words, the microwave transmitted through the arc tube 34 is 9. absorbed by this metal net.

This results in microwave loss.

As described above, some of the microwaves are absorbed by shielding bodies such as metal netting, so leakage to the outside of the device can be avoided, but the microwaves radiated from the antenna 33 cannot be used almost completely. There was a problem.

That is, the light conversion effect of the microwaves emitted by the magnetron 31 (a decrease in lamp efficiency, etc.) was observed.

There was still room for improvement.

[Purpose of the invention]

The present invention was developed in view of the problems of the prior art described above, and reflects microwaves transmitted through two arc tubes by a metal conductor that functions as a cavity resonator.

By connecting it to the arc tube again and contributing to one light emission,
An object of the present invention is to provide a microwave discharge light source device that suppresses microwave loss.

[Summary of the invention]

The present invention includes a microwave oscillator, a waveguide for transmitting microwaves oscillated by the microwave oscillator, and one end of which is protruded into the waveguide and the other end of which is led out of the waveguide. An antenna made of a metal conductor, an arc tube provided to surround the antenna led out of the waveguide, and an arc tube disposed around the arc tube to function as a cavity resonator.

A microwave discharge light source device comprising a metal conductor having a transparent part.

The microwave radiated from the antenna excites the gas sealed in the arc tube 9, and the microwave transmitted through the arc tube 9 is reflected by the metal conductor that acts as a cavity resonator and returns to the arc tube again. Provided is a microwave discharge light source device that can suppress loss of microwaves because it contributes to light emission.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below using the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of a microwave discharge light source device according to the present invention.

As shown in the figure, at one end of the waveguide 1, one frequency is, for example, two
A magnetron 2 that oscillates microwaves of 450 MHz is attached via a metal gasket. waveguide 1
An opening 3 having a diameter of approximately *401ElK is provided on the side surface of the other end. A cylindrical antenna 4 made of a metal conductor such as copper is inserted into the opening 3, and one end of the antenna 4 is fixed inside the waveguide 1 and the other end is fixed so as to protrude a predetermined length outside the waveguide 1. has been done. Further, a light emitting tube 5 is disposed to cover the antenna 4 projecting outside the waveguide 1. This arc tube 5 has a bell-shaped inner glass tube and an outer diameter of 55 mm.
n, and a bell-shaped outer glass tube with a height of 120 mm are hermetically joined to each other, and a discharge medium 9 that emits light when excited by microwaves is placed in the space formed by these tubes, such as mercury and argon. It is filled with a rare gas.

Further, a metal conductor 61 having a transparent portion is provided so as to cover the arc tube 5 in a cylindrical shape. This metal conductor 61
To explain this in more detail, in this embodiment, a metal mesh made of copper wire and having a mesh size of about 3-B is formed into a cylindrical shape with a diameter of 100we and a height of 130m. At least in this embodiment, if the metal conductor 61 is formed in this way, it functions as a cavity resonator 71 for the 2450 MH2 microwave (in other words, the 245 MH2
0MH2 resonance space is formed), and since each mesh of the metal mesh is a transparent part, it was confirmed that more than 90% of the emitted radiation in the ultraviolet, visible, and infrared regions is transmitted. ing.

In this embodiment, the cover 8 whose inner surface K is coated with, for example, aluminum oxide, is disposed outside the metal conductor 61, thereby intensifying the downward light emission in the figure.

Next, the operation of the microwave discharge light source device configured as above will be explained.

Microwaves emitted from a magnetron 2, which is a microwave oscillator, propagate through a waveguide 1 and reach an antenna 4, and are radiated to the inner surface of an arc tube 5 through this antenna 4.

This microwave excites the rare gas sealed in the arc tube 5 and generates discharge plasma, and a part of it excites the rare gas sealed in the arc tube 5.
Transparent.

This leads to a metal conductor 61 disposed around the arc tube 5.

As described above, since the metal conductor 61 forms the cavity resonator 71, this microwave is reflected and reaches the emission v5 again, exciting the rare gas sealed in the two arc tubes 5. As described above, microwaves are radiated from the inside of the nine arc tubes 5 by the antenna 4, and the microwaves transmitted through the one arc tube 5 are also reflected by the metal conductor 61 and radiated to the arc tube 5. In other words, discharge plasma is generated near the inside and outside of the arc tube 5, respectively. The light generated by each discharge plasma is reflected by the cover 8 or directly transmitted through the openings (mesh) of the metal mesh forming the metal conductor 61 and is irradiated to the outside of the device.

According to this embodiment, the microwaves emitted from the magnetron 2 can effectively contribute to the excitation of the rare gas sealed in the arc tube 5. Furthermore, since a metal mesh is used for the metal conductor 61 forming the cavity resonator, the ventilation performance for one arc tube 5 is excellent.

Next, another embodiment of the microwave discharge light source device according to the present invention is shown in FIG. 2 and will be described below.

The structural feature compared to the first embodiment is that the cavity resonator 7
The metal conductor 62 forming the cylindrical body 2 is composed of a tube body 62a made of aluminum, for example, and a metal mesh 62b attached to one end of the tube body 62a.

The operating principle and advantages of this embodiment are similar to those of the first embodiment.

Next, another embodiment of the microwave discharge light source device according to the present invention is shown in FIG. 3 and will be described below.

A feature of the structure compared to the first and second embodiments is that the metal conductor 63 forming the cavity resonator 73 is formed into a mesh shape by etching a thin metal plate such as aluminum. It consists of a tube body 63a made from a flat plate, and a metal mesh 63b that is gently inserted into the tube body 63a.

In other words, the metal mesh 63b has a structure that allows it to move in the axial direction (vertical direction in the drawing) K of the tubular body 63a.

According to this embodiment, the cavity length of the cavity resonator 73 formed by the metal conductor 63 can be changed by moving the metal net 63b.

As is well known, it is extremely easy to set the resonance state depending on the cavity length to an optimum value )'.

In the above embodiments, numerical values etc. are used to determine the shape,
Although the materials and the like are described in detail, there is no need to stick to these specifications, and it is possible to achieve the purpose of the present invention with other specifications.

For example, the cavity resonator formed of a metal conductor is not limited to the cylindrical one described in the embodiments, but it may be sufficient as long as it satisfies the condition that microwaves are reflected back and forth and resonated. Here, to give an example of this condition, H wave (Hz ~ 0. Eχ = 0)
A rectangular cavity resonator (width a, height,
The length C) is Ql" Hp := (""/B* + n'6t
+ ”/c*) r” (here ω is the resonant frequency m,
It is known that it is theoretically formed when the following conditions are met (n and l are integers).

In addition, the conditions for forming a cylindrical resonator (diameter R9 length) for the E-wave (Hχ:O, εχ←0) microwave are (here, λ is the resonant wavelength, k is the microwave It is generally known as a theory that it is expressed by the value determined by the mode.

In addition, the light-transmitting part of the metal conductor is not limited to one formed of a metal net as shown in the embodiment, but may also have the function of transmitting the light emitted by the arc tube and blocking microwaves. Good.

Furthermore, the shape of the antenna does not necessarily have to be cylindrical; it is sufficient that it has the function of radiating microwaves to the nine arc tubes.

Other 0: Apply phosphor to the inner wall of the arc tube.

Known techniques such as obtaining an arbitrary emission wavelength can also be applied.

〔Effect of the invention〕

According to the present invention, both of the microwaves transmitted through one arc tube together with the microwave radiated to nine arc tubes, reflected by the metal conductor forming the cavity resonator, and irradiated to the arc tube again are
Since it is effectively used for light emission, it is possible to provide a microwave discharge light source device that can suppress microwave loss.

[Brief explanation of drawings]

1 to 3 are block diagrams showing embodiments of the present invention. FIG. 4 is a block diagram showing a conventional microwave discharge light source device. 1... Waveguide, 2... Magnetron. 3...Aperture, 4...Antenna. 5... Arc tube, 61, 62, 63.
...Metal conductor. 71, 72, 73...Cavity resonator agent patent attorney Yudo Noriyuki Chika Yukio Yuyama Figure 4

Claims (1)

[Scope of Claims] A microwave oscillator; a waveguide for transmitting microwaves oscillated by the microwave oscillator; one end guided into the waveguide and the other end guided outside the waveguide. an antenna made of a metal conductor led out to the outside of the waveguide; an arc tube provided to surround the antenna led out to the outside of the waveguide; ,
A microwave discharge light source device comprising a metal conductor that functions as a cavity resonator.