JPH0531803Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention is a process in which treatment is performed by ultraviolet irradiation,
The present invention relates to a microwave-excited electrodeless arc tube used in an ultraviolet light emitting device used, for example, in the process of curing ultraviolet curable resin.

[Prior art] Conventionally, paint, ink,
Surface hardening treatment of surfaces coated with resin, paint, etc.
Processes such as the synthesis and processing of chemical substances through photochemical reactions are carried out. The light sources used in these processes are required to have high efficiency and an appropriate output energy level, and electrodeless light emitting devices excited by microwaves are used (for example, (See Publication No. 44228, etc.)

FIG. 3 is a cross-sectional view schematically showing the main parts of a conventional microwave-excited electrodeless light-emitting device, in which 1 is a microwave-excited electrodeless arc tube (hereinafter referred to as arc tube) filled with mercury and argon gas; 2a and 2b are supporting columns that support the arc tube 1; 3 is an elliptical mirror; 4 is a microwave cavity wall that forms a non-resonant microwave cavity; and 5a and 5b are waveguides that guide microwaves. There are holes on the sides that do not allow electromagnetic waves to pass through, but allow cooling air to pass through. Also, 4a, 4b
are coupling slots that connect the waveguides 5a and 5b to the microwave cavity wall 4; 6a and 6b are magnetrons that oscillate microwaves; 7a and 7b are ventilation tubes that pass cooling air; and 8 covers this light emitting device. It is the outer box.

In the light emitting device shown in Fig. 3, the magnetron 6
The high-density microwave energy generated from a and 6b propagates through the waveguides 5a and 5b, respectively, and acts on the gas in the arc tube 1 through the microwave cavity from the coupling slots 4a and 4b to generate plasma. They form and further collide with particles in the plasma to excite the particles in the plasma, and in the process ultraviolet and visible light are emitted. The emitted ultraviolet rays and visible rays are irradiated directly and reflected by the mirror 3 onto a workpiece (not shown) to be processed. 4' is a metal mesh that transmits light but not microwaves.

Incidentally, the arc tube 1 has a diameter of 10 mm, and is filled with mercury as a luminescent material and argon gas as a buffer gas, which evaporates and becomes 1 to 2 atmospheres during lighting. The microwave cavity wall 4 is designed in consideration of the transmission loss that occurs when the microwave energy generated by the magnetrons 6a and 6b propagates into the arc tube 1, and also the dimensions of the arc tube 1 and the magnetron 6.
The shape is determined by the magnitude of the output energy of a and 6b, the microwave coupling mode, etc.

Also, during the light emitting operation of the arc tube 1, the arc tube 1 is approximately
It is necessary to uniformly cool the tube wall of the arc tube 1 so that the temperature does not rise above 800° C. and cause devitrification. In this case, in the case of a discharge tube with a thick electrode such as 25 mm in diameter, the distance between the discharge tube and the mirror that covers it is narrow during cooling, and the heat load on the tube wall is small, so it is necessary to cool it by forced exhaust. However, in the case of the electrodeless arc tube of this invention, the outer diameter of the tube is small, about 10 mm, so the distance from the mirror 3 is large, so the heat load on the tube wall is lower than that of the electrodeless tube. Due to its large size and the need to ensure that a constant amount of air hits every part of the tube wall of arc tube 1, the third
Cooling is performed by blowing air in the direction indicated by the arrow in the figure.

The microwaves generated from the two magnetrons 6a, 6b are coupled to the coupling slots 4a, 4.
At the center of the arc tube 1, which is equidistant from b,
Microscopic standing waves may interfere with each other and become zero or minimum. Therefore, in the center of the arc tube 1, there is less coupling of microwaves than at both ends, and the rate at which the enclosed mercury or argon gas is heated and excited is small. Therefore, cooling of the central part of the arc tube 1 can be suppressed by reducing the size of the hole provided in the mirror 3 through which the cooling air passes at the central part in the longitudinal direction, or as shown in FIG. Traditionally, it has been done to make the material thinner.

FIG. 4 is a diagram schematically showing a conventional microwave-excited electrodeless arc tube, in which the central portion 30 of the arc tube is tapered to be thinner than both ends 31 and 32; The outside diameter of the part is 11 mm, and the outside diameter of the central part is 8 mm.

[Problems to be solved by the invention] As mentioned above, in the conventional microwave-excited electrodeless arc tube, due to the coupling method of the microwave to be excited, the absorption of microwaves in the center of the arc tube is small. , the temperature at the center does not rise as much as the temperature at both ends, and the vaporization state of the mercury sealed in the arc tube does not become uniform.

Therefore, the tube wall of the arc tube is tapered to be thinner at the center and thicker at both ends to prevent mercury from recondensing in the center. Due to its nature, the wall of an arc tube must have a high melting point and high transparency, so quartz is usually used, and it is manufactured by heating and molding a quartz tube with an oxygen-hydrogen burner. Ru.

However, it is not easy to process a quartz tube so that the center part is tapered with respect to both ends, and it is difficult to produce a product with uniformity.Furthermore, the workability is poor. In particular, it is difficult to taper while maintaining the angle as designed. Moreover, the cost also increases.

This invention was devised to solve this problem.It has a simple structure, and when incorporated into a conventionally known electrodeless light emitting device, there is no recondensation of the luminescent material in the central part, and it is It is an object of the present invention to provide a microwave-excited electrodeless arc tube and a method for manufacturing the same, which can produce a product with good workability, easy processing, and no variation.

[Means for Solving the Problems] In order to achieve the above object, the microwave-excited electrodeless arc tube of this invention has a pair of straight glass tubes having the same inner diameter, and a pair of straight glass tubes having straight tubes on the inner surfaces of each tube. The pair of straight glass tubes are coupled by inserting another straight glass tube having an outer diameter smaller than the inner diameter of the glass tube or by joining the end faces and welding.

[Function] With the above configuration, it is easy to manufacture an arc tube without recondensation of the luminescent material, and it is possible to obtain a uniform product.

[Example] FIG. 1 is a sectional view of an arc tube that is an embodiment of this invention, and FIG. 2a is an explanatory diagram of the main part of the method for manufacturing the arc tube of FIG. 1. FIGS. 2b and 2c are explanatory diagrams of the main parts of a method for manufacturing an arc tube, which is another embodiment of FIG. 2a.

In Fig. 1 and Fig. 2a, b and c, 10 denotes an arc tube, 11a, 11b and 11c denote one of a pair of straight glass tubes, and 12a and 12b denote one of a pair of straight glass tubes.
b, 12c are the pair of straight glass tubes 11a
and other straight glass tubes having a small outer diameter for connecting 11a, 11b and 11b, and 11c and 11c, respectively. 13 is a stub.

The arc tube 10 manufactured by the method shown in FIGS. 1 and 2a is a pair of straight glass tubes 11a with an outer diameter of 10 mm, a tube wall thickness of 1 mm, and an inner diameter of 8 mm. One end of another straight glass tube 12a having a smaller outer diameter than the tubular glass tube 11a (outer diameter 8 mm, wall thickness 1 mm, tube inner diameter 6 mm) is inserted and welded by heating with an oxygen-hydrogen burner. Next, the other end of this straight glass tube 12a with a small outer diameter is inserted into the end of another straight glass tube 11a, and heated and welded in the same manner as described above.
a, 11a can be combined as an arc tube with a length of 238 mm via another straight glass tube 12a.
After that, luminescent materials such as mercury and halide iron,
After filling the tube with a buffer gas such as argon and the like, the stub 13 is attached to complete the arc tube 10.

In addition, in FIG. 2b, which is another example,
The ends of a pair of straight glass tubes 11b of the same size as in FIGS. 1 and 2a are connected to the glass tube 11.
While turning b, heat the end portion 11b' with an oxygen-hydrogen burner and bend it inward. One end of another straight glass tube 12b having a slightly smaller outer diameter than the other straight glass tube 12a in FIG. 1A is inserted and welded by heating with an oxygen-hydrogen burner. next,
The other end of this straight glass tube 12b with a small outer diameter is inserted into another straight glass tube 11b whose end is similarly bent, heated in the same manner as described above, and welded to form a straight glass tube. 11b, 11b as 1
Can be combined as a book glass tube. After that, the tube is filled with a luminescent material such as mercury or iron halide, and a buffer gas such as argon.
By attaching and sealing a stub (not shown), an arc tube with a tube length of approximately 238 mm is completed.

Furthermore, in FIG. 1c which is another embodiment, the end portion 1 of the straight glass tube 11c is heated and bent inward as in the case of FIG. 1b.
The side surface of 1c' and the side surface of one end of another straight glass tube 12c whose inner diameter is slightly smaller than that of the other straight glass tube 12a shown in FIG. do. Thereafter, similarly, the side surface of the other end of the straight glass tube 12c and the side surface of the inwardly bent end 11c' of another straight glass tube 12c are heated and welded to join the end surfaces to form a single glass tube. Can be combined as a tube. Then, in the same manner as in FIGS. 2a and 2b, the tube is filled with an enclosure, and a stub (not shown) is attached and sealed to complete an arc tube with a length of 238 mm.

Note that the size of the inner diameter of the other straight glass tube 12 relative to the inner diameter of the pair of straight glass tubes 11 is appropriately determined according to the distribution of the coupled microwaves so that the luminescent material such as mercury does not recondense. .

All of the above-mentioned arc tubes were filled with 25 mg of mercury and argon gas at 15/760 atm when not lit, using the F450-10 lamp system manufactured by Fusion System Corporation.
As a result of irradiating microwaves with an output of 3 kW and a frequency of 2450 MHz, an illuminance of 825 mw/cm ² was obtained at a position 110 mm directly below the center of the arc tube 10. At that time, no recondensation of mercury was found in the arc tube.

[Effects of the invention] As explained above, the microwave-excited electrodeless arc tube of this invention has a pair of straight glass tubes having the same inner diameter, each having an outer diameter smaller than the inner diameter of the straight glass tubes. Since the above-mentioned pair of straight glass tubes are connected by inserting another straight glass tube having a diameter or by joining and welding the end faces, it is easy to manufacture an arc tube without recondensing the luminescent material. This has the effect that there is no variation in products and costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an arc tube that is an embodiment of this invention, Fig. 2 a is an explanatory diagram of the main part of the method for manufacturing the arc tube of Fig. 1, and Fig. 2 b and c are the same as Fig. 2 a. An explanatory diagram of the main parts of the method for manufacturing an arc tube, which is an example of
The figure is a cross-sectional view schematically showing the main parts of a conventional microwave-excited electrodeless light emitting device, and FIG. 4 is a diagram schematically showing a conventional microwave-excited electrodeless arc tube. In the figure, 10... arc tube, 11... a pair of straight glass tubes, 12... another straight glass tube, 13...
...Stub, 14...Oxygen-hydrogen burner.

Claims (1)

[Scope of utility model registration request] By inserting another straight glass tube having an outer diameter smaller than the inner diameter of these straight glass tubes into the inner surfaces of each of a pair of straight glass tubes having the same inner diameter, or by welding the ends by joining them, A microwave-excited electrodeless arc tube characterized by having a configuration in which a pair of straight glass tubes are combined.