JP2542952Y2 - Microwave electrodeless light emitting device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave electrodeless light-emitting device which generates ultraviolet rays by exciting an electrodeless arc tube with microwaves.

[0002]

2. Description of the Related Art In recent years, ultraviolet rays have been widely used for curing and drying of UV-curable adhesives and inks, curing of special paints, other coating surface treatment processes, chemical reactions of chemical substances, and the like. As a device for generating an ultraviolet ray, a microwave electrodeless light emitting device that irradiates a microwave to an electrodeless arc tube in which a light emitting material such as mercury is sealed and excites the light emitting material to generate an ultraviolet ray has been proposed. (Japanese Patent Laid-Open No. 50-541
No. 72, JP-A-2-189805, etc.).

FIG. 5 schematically shows a conventional microwave electrodeless light emitting device, FIG. 6 is a sectional view taken along line XX of FIG. 5, and FIG. 7 is a sectional view taken along line YY of the microwave cavity of FIG. It is. Reference numeral 1 denotes an electrodeless arc tube in which a light emitting material such as mercury is sealed in a rod-shaped glass tube. 2 is a microwave cavity, and 3 is a microwave cavity wall formed of a metal material. The microwave cavity wall 3 is constituted by a wall (hereinafter, abbreviated as “blower side wall”) 31 on the side through which the cooling air from the blower 8 passes, and a side wall 32.

Reference numeral 4 denotes a dielectric mirror, and the electrodeless arc tube 1
Is condensed in the irradiation direction (the direction of arrow A). The sectional shape of the reflection surface of the dielectric mirror 4 is an elliptical or parabolic concave shape. Reference numeral 5 denotes a magnetron as microwave generating means. 6 is a waveguide for guiding microwaves. Reference numeral 7 denotes a mesh, which forms one wall of the microwave cavity 2 and transmits the generated ultraviolet light without transmitting the microwave. That is, the mesh 7 transmits ultraviolet rays but functions as a short-circuit plate for microwaves. Reference numeral 8 denotes a blower for cooling the electrodeless arc tube 1. An antenna 9 couples the microwave cavity 2 and the waveguide 6. 91
Is an opening through which the antenna 9 passes.

In the apparatus shown in FIG. 5, the magnetron 5 is operated to excite vapor such as mercury sealed in the electrodeless arc tube 1, where discharge starts to generate ultraviolet rays. The ultraviolet rays generated at this time are radiated in all directions, but if the electrodeless arc tube 1 is positioned in advance at the focal point of the dielectric mirror 4, the ultraviolet rays are reflected by the dielectric mirror 4 and collected in the direction of the mesh 7. Then, it passes through the mesh 7 and proceeds as it is. Therefore, by arranging the object to be processed in front of the mesh 7,
Processing such as curing and drying of the adhesive or paint can be performed immediately. In particular, by sequentially moving the objects to be processed in front of the mesh 7 by a belt conveyor or the like, a large amount of processing can be continuously performed.

The cooling air from the blower 8 is provided to the ventilation hole 61 provided in the waveguide 6, the ventilation hole 33 provided in the ventilation side wall 31 of the cavity wall 3, and to the dielectric mirror 4. It is sent to the electrodeless arc tube 1 through the vent hole 41.

[0007]

However, in the conventional microwave electrodeless light emitting device shown in FIG. 5, the electrodeless light emitting tube 1 is cooled by the cooling air from the blower 8, so that the temperature rise is prevented to some extent. However, the temperature rise of the electrodeless arc tube 1 does not always occur uniformly in the longitudinal direction. That is, when the electrodeless arc tube 1 emits light, a temperature difference occurs in the longitudinal direction. In particular, an end portion inside the electrodeless arc tube 1, that is, the inner end portion 10 tends to be higher in temperature than the central portion 20, and the inner end portion 10 In this case, problems such as devitrification occur. In order to solve this problem, the inner end portion 10 which becomes hot
Although it is conceivable to provide a large-sized air blower capable of sufficiently cooling the device, this method is not preferable because power consumption increases and the device becomes larger. In addition, the central portion 20, which does not become as hot as the inner end portion 10, may be excessively cooled.

Therefore, an object of the present invention is to make the electrodeless arc tube uniform in its longitudinal direction by a small blower so that the inner end of the electrodeless arc tube does not become hot compared to the center. An object of the present invention is to provide a microwave electrodeless light emitting device that can be cooled.

[0009]

To achieve the above object, a microwave electrodeless light emitting device according to the present invention comprises a rod-shaped electrodeless light emitting tube in which a light emitting material is sealed, and an electrodeless light emitting tube. A cavity wall forming a microwave cavity, microwave generating means, microwave coupling means for coupling the microwave generated by the microwave generating means to the electrodeless arc tube, and cooling air for the electrodeless arc tube In a microwave electrodeless light emitting device having a blowing means for sending through a body wall, a wall (blowing side wall) on the side of the cavity wall through which cooling air passes has a size not larger than a dimension which is a cutoff wavelength of microwaves. A plurality of vent holes, and a unit by a vent hole at a position corresponding to the inner end portion such that the air flow toward the inner end of the electrodeless arc tube is larger than the air flow toward the central portion. Aperture ratio per area And said that it has heard.

In the above-mentioned microwave electrodeless light emitting device, a dielectric mirror for reflecting ultraviolet light generated from the electrodeless light emitting tube is disposed in the microwave cavity, and the dielectric mirror is provided in the dielectric mirror. A plurality of ventilation holes are provided along the longitudinal direction of the electrodeless arc tube, and the dielectric at the position corresponding to the inner end is so set that the airflow toward the inner end of the electrodeless arc tube is larger than the airflow toward the center. The aperture ratio per unit area by the ventilation hole provided in the body mirror is increased.

[0011]

According to the present invention, the opening ratio per unit area of the ventilation hole at the position corresponding to the inner end of the electrodeless arc tube among the ventilation holes provided on the air blowing side wall of the cavity wall is increased. Since the airflow toward the inner end of the electrode arc tube is made larger than the airflow toward the center, the inner end of the electrodeless arc tube can be prevented from becoming hotter than the center, and the electrodeless Cooling can be performed substantially uniformly along the longitudinal direction of the arc tube. Further, by configuring the ventilation holes provided in the dielectric mirror in the same manner as described above, the same effect can be obtained even when the dielectric mirror is provided.

[0012]

Embodiments of the present invention will be described below. FIG.
FIG. 3 is a schematic view showing an embodiment of the microwave electrodeless light emitting device according to the present invention. In FIG. 1, reference numeral 10 denotes an inner end of the rod-shaped electrodeless arc tube 1, and reference numeral 20 denotes a central portion at the center between the inner ends 10, 10. FIG. 2 shows only the wall (blower side wall) 31 of the cavity wall 3 in FIG. As shown in FIG. 2, a first ventilation hole 34 and a second ventilation hole 35 are provided on the ventilation side wall 31 at positions substantially corresponding to the rod-shaped electrodeless arc tube 1,
Third air holes 36 are provided on both sides.

The first vent hole 34 is provided at a position corresponding to the inner end portion 10 of the electrodeless arc tube 1 and its vicinity, and the second vent hole 35 is formed at the center portion 20 of the electrodeless arc tube 1. It is provided at a position corresponding to other portions including the above.
The ventilation holes 34a and 35a constituting the first ventilation hole 34 and the second ventilation hole 35 are of substantially the same size, but are arranged more densely in the first ventilation hole 34 than in the second ventilation hole 35. Thus, the aperture ratio per unit area is increased. The size of each of the ventilation holes 34a and 35a varies depending on the thickness of the cavity wall 3, but is not particularly limited as long as it is a size that blocks microwaves. When the thickness of the cavity wall 3 is, for example, 2 mm, the diameter of each ventilation hole is set to 1/10 or less of the microwave wavelength. One example of the area of each vent hole is about 16 mm ² .

As described above, by changing the arrangement pitch of the ventilation holes while sufficiently satisfying the condition of the size of each ventilation hole required from the relationship with the cutoff wavelength of the microwave, the electrodeless arc tube 1 is formed. The amount of air received by the inner end portion 10 is larger than the amount of air received by the central portion 20 to achieve uniform temperature in the longitudinal direction. As an example of the arrangement pitch of the ventilation holes, the ventilation holes 34a are provided at intervals of about 5 mm in the first ventilation holes 34, and the ventilation holes 35a are provided at intervals of about 7 mm in the second ventilation holes 35. The arrangement length L of the ventilation hole 34 is, for example, 20 mm. Reference numeral 91 denotes an opening into which the antenna 9 is inserted.

FIG. 3 shows only the dielectric mirror 4 arranged in the microwave cavity 2 in FIG. 1 and viewed from the irradiation surface side. The dielectric mirror 4 has an elliptical cross section, but has a flat shape as viewed from the irradiation surface side. The reflection surface of the dielectric mirror 4 is formed of a metal oxide deposited film. Ultraviolet light generated from the electrodeless arc tube 1 is reflected by the reflecting surface and radiated outward from the mesh 7.

In order to facilitate the formation of a deposited film, the dielectric mirror 4 is composed of four divided bodies 4a, 4b, 4c and 4d. That is, it is easier to provide a vapor deposition film individually for each of the four divided bodies than to form a vapor deposition film on the entire inner surface of the dielectric mirror 4 at once. The dielectric mirror 4 is provided with a plurality of ventilation holes 41 along the longitudinal direction of the electrodeless arc tube 1. A semicircular notch is also provided at a portion where the four divided bodies are joined to each other, and when the divided bodies are combined, the corresponding two notches form the ventilation hole 41. At a position corresponding to the inner end portion 10 of the electrodeless arc tube 1, a ventilation hole 42 having a notch larger than the ventilation hole 41 is provided, and the aperture ratio per unit area of the ventilation hole is increased. The air flow toward the inner end 10 of the electrodeless arc tube 1 is made larger than the air flow toward the central portion 20.

The size of the ventilation holes 41 and 42 is not particularly limited, but is set so as not to impair the function of the dielectric mirror 4 for reflecting ultraviolet rays. For example, the vent 41 is 16 to 36 mm ² (4 to 6 mm in diameter), and the vent 42 is
It is 10 × 20 mm. Thus, not only the cavity wall 3 but also the dielectric mirror 4 can cool the inner end 10 of the electrodeless arc tube 1 strongly. The ventilation hole 42 may be configured with an opening like the ventilation hole 41 instead of the notch.

FIG. 4 is an experimental result showing the effect of the present invention. The solid line shows the case of the conventional microwave electrodeless light emitting device, and the broken line shows the case of the microwave electrodeless light emitting device of the present invention shown in FIG. In the conventional microwave electrodeless light-emitting device used in the experiment, the ventilation holes of the same size are uniformly formed in portions corresponding to the longitudinal direction of the electrodeless light-emitting tube 1 in the ventilation side wall 31 and the dielectric mirror 4. They are arranged on a pitch. In this experiment, the tube wall temperature was detected at five detection points (A to E) provided at uniform intervals in the longitudinal direction of the electrodeless arc tube 1. In this case, the points A and E indicate the tube walls of the inner end 10 on one and the other, respectively, and C
The dots indicate the tube wall of the central part 20. The electrodeless arc tube 1 has a distance of about 238 mm from the inner end 10 and an inner diameter of 6 mm.
A mm mercury lamp was used. The detection of the tube wall temperature was performed when 5 minutes had elapsed after lighting. As is apparent from FIG. 4, the temperature of the inner end portion 10 of the electrodeless arc tube 1 is very high at about 850 ° C. and about 820 ° C. in the conventional apparatus, whereas it is close to about 700 ° C. in the apparatus of the present invention. Can be lowered to
Further, it can be seen that the difference in temperature distribution in the longitudinal direction of the electrodeless arc tube 1 can be suppressed to a considerably small value.

[0019]

As described above in detail, according to the microwave electrodeless light emitting device of the present invention, the inner end of the electrodeless arc tube where the temperature is high has a larger air flow than the central portion. Can be shed. Therefore, it is possible to prevent the inner end portion of the electrodeless arc tube from being devitrified or perforated.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of a microwave electrodeless light emitting device according to the present invention.

FIG. 2 is a bottom view of a part of the cavity wall in FIG. 1;

FIG. 3 is a view of the dielectric mirror in FIG. 1 as viewed from an irradiation surface side.

FIG. 4 is a graph showing experimental results.

FIG. 5 is a schematic view of a conventional microwave electrodeless light emitting device.

FIG. 6 is a sectional view taken along line XX of FIG. 5;

FIG. 7 is a sectional view taken along line YY of FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrodeless arc tube 2 microwave cavity 3 cavity wall 31 ventilation side wall 32 side wall 33 ventilation hole 34 first ventilation hole 35 second ventilation hole 36 third ventilation hole 4 dielectric mirror 41 ventilation hole 42 ventilation hole 5 microwave Generation means 6 Waveguide 61 Vent hole 7 Mesh 8 Blowing means 9 Antenna 91 Opening

Claims (2)

(57) [Scope of request for utility model registration] 1. A rod-shaped electrodeless arc tube enclosing a light-emitting material, a cavity wall on which the electrodeless arc tube is arranged to form a microwave cavity, microwave generating means, and microwave generating means. In a microwave electrodeless light emitting device comprising: microwave coupling means for coupling the generated microwave to the electrodeless light emitting tube; and blowing means for sending cooling air for the electrodeless light emitting tube through the cavity wall. On the wall on the side through which the cooling air passes, a plurality of ventilation holes having a size equal to or less than the size that is the cut-off wavelength of the microwave is arranged, and the amount of air flowing toward the inner end of the electrodeless arc tube is at the center. A microwave electrodeless light emitting device characterized in that an aperture ratio per unit area of a ventilation hole at a position corresponding to the inner end portion is increased so as to be larger than an amount of air flowing toward the electrode. 2. The microwave electrodeless light emitting device according to claim 1, wherein a dielectric mirror for reflecting ultraviolet light generated from the electrodeless arc tube is disposed in the microwave cavity, and the dielectric mirror is provided in the dielectric mirror. A plurality of ventilation holes are provided along the longitudinal direction of the electrode arc tube, so that the air volume toward the inner end of the electrodeless arc tube is larger than the air volume toward the center.
A microwave electrodeless light emitting device characterized in that an aperture ratio per unit area of a ventilation hole provided in a dielectric mirror at a position corresponding to the inner end is increased.