JPS6139449A - Microwave discharge light source device - Google Patents

Abstract

PURPOSE:To improve light emitting efficiency ever so better, by installing a concave part in a light emitting tube sealing a discharge medium inside, while inserting an antenna of a magnetron into this concave part, and radiating a microwave from the inside of the light emitting tube. CONSTITUTION:Operating a magnetron, when a microwave is emitted out of its antenna 15, since the circumference of this antenna 15 is covered with a concave part 18, the microwave emitted radially out of the antenna 15 is made incident inside a discharge space 19 from the inside of the light emitting tube 16. As a result, uniform discharge is excited inside the discharge space 19 along the circumferential direction, whereby ultraviolet rays generated by this discharge is radiated out of the light emitting tube 16. And, part of the ultraviolet rays is radiated outward from a direct light radiating port 22, while the rest is reflected on a light reflecting surface 21 afterward, it is radiated outward through the light radiating port 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a microwave discharge light source device that utilizes microwave discharge.

[Technical background of the invention and its problems]

Recently, an electrodeless light source using microwave discharge has been attracting attention because of its long life, and attempts have been made to use it as a light source for, for example, an LSI transfer system.

By the way, as an electrodeless light source using microwaves, conventionally, for example, as schematically shown in FIG. , an arc tube 4 made of a quartz bulb sealed with a discharge material is placed at a location where the microwaves emitted from the microwave output section 3 of the magnetron 2 are concentrated, and microwaves are applied to the arc tube 4. By doing so, a discharge is caused in the discharge body in the arc tube 4 to generate, for example, ultraviolet rays of 200 nm or less, or, although not shown, the microwave emitted from the microwave output section 3 is transmitted through the waveguide. One is known in which the light is guided to the arc tube 4 through the tube.

However, in the case of any of the above-mentioned prior arts, since the microwave output section 3 and the arc tube 4 are separated within the device main body 1, the microwaves are attenuated in the process of being guided through the arc tube. In addition, since microwaves are irradiated from the outside of the arc tube, there is a problem in that the microwaves tend to leak to the outside, resulting in a corresponding decrease in light delivery efficiency.

[Purpose of the invention]

The present invention was made based on these circumstances, and
An object of the present invention is to provide a microwave discharge light source device that has less attenuation and leakage of microwaves and can improve luminous efficiency.

[Summary of the Invention] That is, in order to achieve the above object, the present invention provides a concave portion in an arc tube that forms an airtight discharge space in which a discharge medium is sealed, and inserts a magnetron antenna into this concave portion. It is characterized in that the microwave is irradiated from inside the arc tube.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In the figure, 11 is a magnetron that generates microwaves, and inside the case 12 that houses this magnetron 11,
A cooling fan 13 is provided. In addition, the code 14
is the power source of the magnetron 11.

One end of the magnetron 11 led out from the case 12 is provided with an antenna 15 that emits microscopic light, and the end on the side of the antenna 15 is provided with a light-emitting device made of quartz glass having translucency and magnetic permeability. A tube 16 is attached. The arc tube 1G of this embodiment has a hollow cylindrical shape with both ends closed as shown in FIG. A recess 18 into which the antenna 15 fits is formed in the portion. Therefore, the arc tube 16 covers the entire circumference of the antenna 15 with its recess 18, and an airtight discharge space 19 surrounding the recess 18 is formed within the arc tube 16. In this discharge space 19, mercury as a discharge medium has a partial pressure of 5×10°3 Torr (
In addition, nitrogen gas is filled as a starting rare gas at a pressure of several to several tens of seven orr.

Further, a reflector 20 having a paraboloid of revolution shape is attached to one end of the magnetron 11 leading out.

The inner surface of the reflector 20 is formed into a light reflecting surface 21 by vapor-depositing aluminum.
The arc tube 16 is concentrically located in the center of the arc tube 1G, and the spherical surface 11 of the arc tube 1G faces the light irradiation port 22 provided on the front side of the light reflecting surface 21. A metal mesh 23 is placed over the light irradiation port 22, and the mesh 23 and the reflector 20 constitute an electromagnetic wave shield section 24 that covers the circumference of the arc tube 1G.

Next, the operation of the above configuration will be explained.

First, operate the magnetron 11, and □ its antenna 1.
Emit microwave from 5. Then, since the antenna 15 is surrounded by the recess 18 of the arc tube 16, the microwaves radially emitted from the antenna 15 enter the discharge space 19 from inside the arc tube 16. As a result, a uniform discharge (plasma) is excited in the discharge space 19 along the circumferential direction, and ultraviolet rays generated by this discharge are emitted from the arc tube 1G. A part of this ultraviolet light is directly irradiated outward from the light irradiation port 22, and the rest is reflected by the light reflection surface 21 and then irradiated outward through the light irradiation port 22.

According to such an embodiment, since the antenna 15, which is the output end of the microwave, is inserted into the recess 18 of the arc tube 16, the microwaves radially emitted from the antenna 15 immediately reach the discharge space. It will be introduced in 2019. Therefore, the microwaves are hardly attenuated before being guided to the discharge space 19, improving efficiency. In addition, since no components for transmitting microwaves such as conventional waveguides are required, the entire device can be made more compact, and the number of components can be reduced, making it possible to provide the device at low cost.

In addition, since the microwaves are emitted radially from inside the arc tube 16, uniform discharge is excited throughout the discharge space 19; It always passes through the discharge space 19, and only the amount that was not absorbed during this passing process is transferred to the arc tube 16.
Since the microwave is radiated outside the microwave, loss due to microwave leakage is reduced, and it becomes possible to efficiently and stably supply light in a desired wavelength range (ultraviolet rays in the case of this embodiment).

Since the circumference of the arc tube 16 is covered by the electromagnetic wave shield section 24, even if the unabsorbed microwaves leak to the outside of the arc tube 16, the electromagnetic wave shield section 24 shields the entire device. leakage to the outside can be prevented.

In this case, since the microwave itself to be shielded by the electromagnetic wave shielding section 24 is weak, the shielding structure can be simplified by this weakness.

Further, since the arc tube 1G of this embodiment has a cylindrical shape, and the closed surface at one end facing the light irradiation port 23 is a spherical surface 17, the radiation direction of the ultraviolet rays from the arc tube 16 is concentrically equalized. will be done. Therefore, as shown in FIG. 4, when the luminance distribution on the light irradiation surface at a certain distance from the light irradiation port 22 is centered on the tube axis X-X of the arc tube 16, it spreads over a wide range. This has the advantage that the same light distribution characteristics as above can be obtained when viewed from any direction passing through the tube axis X-X, and a large area can be irradiated.

In the present invention, the discharge medium sealed in the discharge space is not limited to mercury, but may be, for example, mercury, krypton, or xenon gas, or a mixture thereof. [Effects of the Invention] According to the present invention described in detail above, microwave Since the microwaves emitted from the output section are immediately introduced into the discharge space of the arc tube, there is almost no attenuation of the microwaves, improving efficiency. In addition, since the microwaves are emitted radially from the inside of the arc tube, a uniform discharge is excited throughout the discharge space, and all of these microwaves are necessarily emitted within the discharge space. At the same time, only the unabsorbed part during this passing process is radiated out of the arc tube, so there is less loss due to microwave leakage, and this improves the luminous efficiency mentioned above. This makes it possible to efficiently and stably supply light.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention, in which FIG. 1 is a sectional view, FIG. 2 is a sectional view taken along line II-I in FIG. 1,
FIG. 3 is a perspective view of an arc tube, FIG. 4 is a light distribution characteristic diagram, and FIG. 5 is a schematic configuration diagram of a conventional microwave discharge light source device. 11... Magnetron, 15... Antenna, 16.
... Arc tube, 18 ... recess, 19 ... discharge space. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] It is equipped with a magnetron that generates microwaves, and an arc tube made of a translucent and magnetically permeable material and having an airtight discharge space in which a discharge medium is enclosed, and the arc tube is configured to generate microwaves from the magnetron. A microwave discharge light source device characterized by having a recess into which an antenna for outputting is inserted.