JPH02117003A - Electrodeless discharging tube apparatus for microwave - Google Patents

Abstract

PURPOSE:To make emission stable instantaneously by a method wherein a discharging tube of an ultraviolet ray source is made electrodeless, and microwaves are absorbed into the discharging tube with a microwave coupling portion whose antenna portion is provided in parallel with the discharging tube. CONSTITUTION:With a microwave electrodeless discharging tube 15 which causes plasma discharge with excitation of microwave used as an ultraviolet ray source, this discharging tube 15 is placed in a cavity with its one face opened to realize constitution wherein microwaves generated by a microwave generator are supplied via a waveguide 13 by a microwave coupling portion 14 consisting of at least a pair of conductors, whose one end is fixed to the waveguide 13 or a wall of the cavity, provided in parallel with the electrodeless discharging tube 15. In other words, the microwaves are supplied to the discharging tube 15 by an antenna portion 14-1 of the microwave coupling portion 14, and plasma is generated in the discharging tube 15. By placing the antenna portion 14-1 approximately in parallel with the discharging tube 15, the microwaves can be efficiently absorbed in the discharging tube 15, thereby permitting emission of the discharging tube 15 to be stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device that emits ultraviolet rays using a plasma discharge discharge tube, irradiates an object with the ultraviolet rays, and causes the ultraviolet rays to react with the object.

[Conventional technology]

Ultraviolet rays are used in various fields, and are used in special paints (U
It is also used to cure V-curing paints.

FIG. 8 shows the configuration of an example of a discharge tube device conventionally used for curing paint.

In the figure, 1 is a step-up transformer, 2 is a phase adjustment capacitor, 3 is a reactor, 4 is an electroded discharge tube, 4-1 is an electrode, 5 is a reflecting mirror, 6 is a shutter, and 7 is an object to be irradiated.

High voltage from the step-up transformer 1 is applied to the discharge tube 4 via the capacitor 2 and reactor 3, causing plasma discharge.

The object to be irradiated 7 is then irradiated with ultraviolet rays generated during plasma discharge.

The reflector 5 is used to increase the efficiency of the effective use of the ultraviolet rays generated in the discharge tube 4, and the shutter 6 prevents the object 7 from being irradiated with extra light that is generated until the discharge stabilizes. This is to prevent this.

[Problem to be solved by the invention]

The conventional device with the above configuration takes several minutes to stabilize the light emission, and during that time, it generates harmful ozone, which is a problem.Since it has electrodes, the evaporated components from the electrode 4-1 are absorbed into the discharge tube. 4 and shorten the life of the discharge tube 4.
Furthermore, there is a problem in that a movable mechanism such as the shutter 6 is prone to failure, and malfunctions due to failure of the shutter 6 occur frequently.

The present invention has been made to solve the above-mentioned problems, and aims to provide an entire device that makes the discharge tube electrodeless, instantly stabilizes generation, and does not require a movable mechanism such as a shutter. purpose.

[Means for Solving the Problems] The device of the present invention uses a microwave electrodeless discharge tube that generates plasma discharge by microwave excitation as an ultraviolet light generation source, and the discharge tube is connected to a cavity with one side open. At least one pair of electrodeless discharge tubes arranged in parallel with the electrodeless discharge tube, one end of which is fixed to the grooved tube or the wall of the cavity, through which the microwaves generated by the microwave generator pass through the waveguide. The configuration is such that the power is supplied by the microwave coupling section of the conductor.

〔Example〕

FIGS. 1(a) and 1(b) show an embodiment of the present invention.

Figures (,) and (b) are a front view and a side view showing the internal structure, where 10 is a power supply section, 11 is an applicator section, 12 is a magnetron, 13 is a waveguide, 14 is a microwave tube coupling section,
15 is an electrodeless discharge tube, 16 is a metal mesh, 17 is a dielectric mirror (cold mirror), 18 is a 7'oA, 19 is a duct, 20 is a heater transformer, and 21 is an excitation valve.

The microwaves generated by the magnetron 12 are each transmitted by a waveguide 13 and supplied to a discharge tube 15 by a microwave coupling section 14 .

Ultraviolet rays generated during plasma discharge from the discharge tube 15 are reflected directly or by the cold mirror 17, transmitted through the mesh 16, and irradiated onto the object.

The discharge tube 15 and the cold mirror 17 are cooled by cooling air sent from the blower 18 through the duct 19. The excitation bulb 21 is used to shorten the time it takes for the discharge tube 15 to stabilize its light emission.

FIG. 2 shows the detailed structure of the light emitting section of the embodiment shown in FIG.

13.1.1, 15, 16, and 17 indicate the same parts as the same reference numerals in FIG. Torso, 2
3 is an insertion metal plate, 24 is a support for the cold mirror 17,
25 is a tap plate for fixing the mesh 16; 26 is a tap plate through which the microwave coupling part 14 is passed;
4 is a coupling hole that connects the inside of the waveguide 13 and the inside of the cavity 22, and 27 and 28 are the cold mirror 17 and the cavity 2, respectively.
2 is a ventilation hole provided in the wall 2 for passing cooling air; 29 is a light absorbing paint; 30 is a ventilation hole provided in the side wall of the cavity 22;

The microwave is transmitted through the antenna section 14- of the microwave coupling section 14.
1 is supplied to the discharge tube 15, and plasma is generated within the discharge tube 15. By arranging the antenna section 14-1 substantially parallel to the discharge tube 15, microwaves can be efficiently absorbed by the discharge tube 15, as shown in FIG. Magnetic field 3 is generated by microwaves transmitted through antenna section 14-1.
1 is formed and generates plasma within the discharge tube 15.

The magnetic field 31 generates a current 32 in the plasma, which in turn generates a magnetic field 31-1.

The same effect can be obtained even if the shape of the antenna part is a straight line, as shown in FIG. 4, but in this case, the shape of the antenna part 14
-1 and the discharge tube 15 must be made as narrow as possible.

However, when the distance d becomes narrower, parts of the discharge tube 15 that are in close contact with the antenna section 14-1 are heated more strongly than other parts, and the discharge tube 15 may be damaged.

As a result of experiments, we found that the shape of the antenna section 14-1 has a wavy shape as shown in FIG. 2, in which the distance d is widened to an extent that the discharge tube 15 is not damaged by local heating, and the antenna part 14-1 has a high microwave coupling efficiency. The results shown in FIG. 5 were obtained.

Both have a large effective area facing the discharge tube 15 of the antenna section 14-1.

As shown in FIG. 6, when the distance between the discharge tube 15 and the bottom plate of the cavity 22 is sufficiently large, the discharge tube 15 is centered around the coupling hole 26.
It may be provided at a position that coincides with the long axis of. If the spacing is narrow and the coupling hole 26 is provided at the position shown in FIG. 6, discharge may occur between the discharge tube 15 and the tip of the coupling portion 14. It needs to be moved off-axis.

The antenna section 14-1 of the microwave coupling section 14 is placed on the same side of the discharge tube 15 as shown in FIG. 7(a), or on the same side of the discharge tube 15 as shown in FIG. 7(b). Cavity 2
It may be installed between the two bottoms, or one side may be installed between the two bottoms as shown in Figure 7 (,)
One device may be installed at the position shown in FIG. 7, and the other at the position shown in FIG. 7(b), so that they are orthogonal to each other.

The light absorbing paint 29 shown in FIG.
It efficiently absorbs light other than ultraviolet rays that has passed through 7 and converts it into heat. The generated heat is radiated to the outside through the holes 30 provided in the wall of the cavity 22 by cooling air from the blower 18, thereby preventing excess heat from being blown onto the object to be irradiated.

〔Effect of the invention〕

As explained above, according to the present invention, the discharge tube as a source of ultraviolet light is electrodeless, and the microwave is sufficiently absorbed into the discharge tube by the microwave coupling section in which the antenna section is arranged parallel to the discharge tube. Therefore, the life of the discharge tube is extended, the light emission is instantly stabilized, a movable mechanism such as a shutter is no longer required, and failures are reduced.

[Brief explanation of the drawing]

Figures 1 (,) and (b) are explanatory diagrams showing one embodiment of the present invention, and Figures 2 (a), (b) and (c) are detailed diagrams of the light emitting part of the embodiment shown in Figure 1. Explanatory diagram showing the structure, 3rd
Figures 4 and 4 are explanatory diagrams showing the operation of the microwave coupling section of the present invention, and Figure 5 (
a), (b), ω) e (d), (e) are explanatory diagrams showing examples of the shape of the antenna part of the microwave coupling part of the present invention, Fig. 6 (a), (b) # (C ) is an explanatory diagram showing another structure of the light emitting part of the embodiment of the present invention, and FIGS. 7(a) and 7(b) are explanatory diagrams showing an example of the arrangement position of the antenna part of the microwave coupling part of the present invention. , FIG. 8 is an explanatory diagram showing an example of a conventional device of this type. DESCRIPTION OF SYMBOLS 10...Power supply part, 11...Azoricator part, 12.
... Magnetron, 13... Waveguide, 14... Microwave coupling section, 14-1... Antenna section, 14-2.
...Support part, 15... Electrodeless discharge tube, 16... Metosh, 17... Cold mirror, 18... Blower,
19...Duct, 20...Heater transformer, 21.
... Excitation valve, 22 ... Cavity, 23 ... Insertion metal plate, 24 ... Support tool, 25 ... Tap plate, 26 ...
...Binding pores, 27, 28. 30... Ventilation hole, 29... Light absorption paint, 313
1-1...Magnetic field, 32...Current Note that the same reference numerals in the drawings indicate the same or corresponding parts. Patent Applicant New Japan Radio Co., Ltd. Figure (a) (b) (c) (d) Figure (a) (b) Figure Figure

Claims (2)

[Claims] (1) An electrodeless discharge tube that generates plasma discharge by microwave excitation is installed in a box-shaped cavity with one side open, and the open side of the cavity blocks microwaves and transmits ultraviolet rays. At least one pair of conductors are arranged parallel to the electrodeless discharge tube, with at least one end fixed to the wall of the cavity, and the microwave generated by the microwave generator passes through a waveguide. A microwave electrodeless discharge tube device configured to supply ultraviolet light to the electrodeless discharge tube through a microwave coupling section, and to transmit ultraviolet rays from the open surface of the cavity and radiate the ultraviolet rays through the mesh. (2) A dielectric mirror is provided in the cavity to reflect ultraviolet rays directed toward the wall of the cavity from the electrodeless discharge tube and radiate the ultraviolet rays from the open surface of the cavity. Microwave electrodeless discharge tube device as described in .