JP2003086139A - Electrodeless field discharge excimer lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeless field discharge excimer lamp not only capable of being easily and surely started and lit with a high frequency wave having a frequency of 1-100 MHz but also capable of providing stable discharge and excellent in luminous efficiency. SOLUTION: This electrodeless field discharge excimer lamp is provided with a hollow discharge vessel filled with discharge gas, external electrodes mounted on the outside of the discharge vessel, a hollow tube having a high insulation property and inserted into a nearly central part of the hollow part of the discharge vessel, and a trigger electrode and an internal electrode mounted on the outside surface of the tube having the high insulation property. The lamp is so structured that the high frequency wave of 1-100 MHz is applied to the internal electrode to generate field discharge, the width A of a tip part of the trigger electrode is set to 0.1-5 mm, and the tip part is brought into contact with the inside of the discharge vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as an ultraviolet light source for curing, surface cleaning, sterilizing or photochemical reaction of a paint, generates excimer molecules by electrodeless electric field discharge, and emits light emitted from the excimer molecules. The present invention relates to improvement of an electrodeless electric field discharge excimer lamp used.

[0002]

2. Description of the Related Art As a technique related to the lamp of the present invention, there are JP-A-2000-133209 and JP-A-200.
A well-known electrodeless electric field discharge lamp that generates excimer molecules by electric field discharge (also known as electrodeless electric field discharge) to which a high frequency is applied and uses ultraviolet rays emitted from the excimer molecules is disclosed in Japanese Patent Application Laid-Open No. 0-311658. There is.

In Japanese Patent Laid-Open No. 2000-133209, a high frequency of 1 MHz is applied to the internal electrodes as a lighting frequency.
Disclosed is an electrodeless electric field discharge lamp which can be applied in the range of 100 MHz to efficiently supply electric power to the discharge space to obtain a uniform and stable discharge.

[0004]

The excimer lamp disclosed in the above publication has high luminous efficiency because it is lit at a high frequency of 1 MHz to 100 MHz, but has a problem that discharge is difficult to start. This is Japanese Unexamined Patent Publication No. 2000-311658.
This is because, as in the publication, since the trigger electrode is wound around the outer surface of the tube having high electric insulation, the starting energy is dispersed on the circumference. In addition, since air as an insulator has entered between the trigger electrode and the discharge vessel, the starting energy is attenuated.

The present invention has been made in view of the above, and not only can it be started and lit easily and reliably at a high frequency of 1 to 100 MHz, but also stable discharge can be obtained and the luminous efficiency is excellent. An object is to provide an electrodeless electric field discharge excimer lamp.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 has a hollow discharge vessel filled with a discharge gas, and an external electrode attached to the outside of the discharge vessel. , A hollow tube having a high electrical insulating property which is inserted substantially in the center of the hollow portion of the discharge vessel, a trigger electrode and an internal electrode attached to the outer surface of the tube having a high electrical insulating property, and the internal electrode A high frequency is applied in the range of 1 to 100 MHz to cause electric field discharge, and the width A of the tip portion of the trigger electrode is
Is 0.1 mm to 5.0 mm, and is an electrodeless electric field discharge excimer lamp configured to be in contact with the inside of the discharge vessel.

According to a second aspect of the present invention, the distance B between the trigger electrode attached to the outer surface of the tube having high electrical insulation and the external electrode attached to the outside of the discharge vessel is 15 mm or less. It is an electrode electric field discharge excimer lamp.

According to the first aspect of the present invention, the width of the tip portion of the trigger electrode of the excimer lamp is made narrower than that of the prior art, so that the starting energy is partially dispersed on the circumference of the tube. Can be focused on. Further, since the trigger electrode has a structure in contact with the inside of the discharge container, the starting energy is not attenuated even if air as an insulator enters between the trigger electrode and the discharge container. Therefore, the lighting can be started quickly.

According to the second aspect of the invention, the lighting start can be performed more reliably by setting the distance between the trigger electrode and the external electrode attached to the outside of the discharge vessel to be 15 mm or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment of the electrodeless electric field discharge excimer lamp according to the present invention. The hollow discharge vessel 1 is made of quartz glass having a total length of about 300 mm, the outer tube has an outer diameter of about 35 mm and an inner diameter of about 32 mm, and the inner tube has an outer diameter of about 11 mm and an inner diameter of about 9 mm. The outer electrode 2 is wound around the outer tube of the discharge vessel 1, and the discharge vessel 1 is filled with 2.0 × 10 ⁴ Pa of xenon gas. Further, in the substantially central portion of the hollow portion of the discharge vessel 1,
A quartz glass tube 3 as a hollow tube having high electrical insulation is inserted, and a trigger electrode 4 is arranged on the outside of the tube 3 having high electrical insulation and an internal electrode 5 is wound. In addition, when the lamp is turned on, the trigger power supply 6 energizes the trigger electrode 4, and the internal electrode 5 receives the high frequency power supply 7
From which a high frequency of 2.65 MHz is applied to cause electric field discharge in the discharge vessel 1. In the figure, 8 is a ceramic base for mounting a lamp, and 9 is a refrigerant outlet as a terminal.

2 (a) and 2 (b) show an embodiment in which the width (A) of the tip portion of the trigger electrode 4 is 2 mm, and is a view showing the structure with the internal electrode 5, and FIG. FIG. 4 is an explanatory diagram showing a positional relationship between the trigger electrode 4 and the external electrode 2.

The trigger electrode 4 for starting needs to be attached at a position near the external electrode 2 as shown in the figure, with a distance to the internal electrode 5 such that no discharge is generated. The trigger electrode 4 can be attached to the discharge vessel 1 at any position on the circumference of the tube axis depending on the application. Further, as shown in the drawing, the tip portion of the trigger electrode is bent in an arc shape so as to have elasticity. Then, since the discharge formed between the external electrode 2 and the trigger electrode 4 partially overlaps the discharge formed between the external electrode 2 and the internal electrode 5, quick start and lighting are possible. .

In the above embodiment, the case where the width A of the tip portion of the trigger electrode 4 is set to 2 mm has been described.
If it is 0.5 to 5.0 mm, the starting energy can be concentrated on a part without being dispersed on the circumference of the tube. If it is less than 0.5 mm, not only is it too thin and complicated to manufacture, but also the mechanical strength is low. If it exceeds 5.0 mm, the width of the tip portion becomes large and it is not possible to concentrate it on a part, and there is a problem that the starting characteristic deteriorates.

Next, an experimental example will be described. The change in the starting voltage of the lamp when the distance B between the trigger electrode 4 and the external electrode 2 shown in FIG. 3 was changed was measured. FIG. 4 shows changes in the starting voltage characteristics of the lamp according to the present invention (A = 2 mm) and the lamp according to the conventional example (electrode tip shape is cylindrical). FIG. 4 shows that the lamp does not start when the distance B between the trigger electrode 4 and the external electrode 2 exceeds 15 mm. This demonstrates that the trigger electrode of the present invention can be started with lower energy than the conventional trigger electrode, and the start is more reliable.

When the excimer lamp is used by incorporating it into a processing apparatus, the refrigerant 10 is flown through the hollow portion of the tube 3 having high electric insulation. The reason for flowing the refrigerant 10 is as follows. High frequency (radio frequency, 1-100 MH
When the voltage of z) is applied to the discharge vessel, high-density plasma is formed in all the spaces in the discharge vessel, and uniform discharge (fog-like discharge) is generated. This is positional, like micro-plasma in the conventional dielectric barrier discharge lamp,
Since there is no temporal fluctuation of plasma, it is possible to increase the ultraviolet ray output per unit area to several tens of times that of the conventional dielectric barrier discharge lamp. However, along with this, the discharge vessel 1
This is because the temperature rise of 1 is excessively large and the discharge vessel is effectively cooled.

As described above, since the luminous efficiency of the electrodeless electric field discharge excimer lamp is remarkably lowered due to the temperature rise of the discharge vessel 1, it is necessary to cool the discharge vessel 1 sufficiently. Therefore, it suffices to directly cool the internal electrode 5 in the central portion of the lamp with the cooling medium, but since a high voltage is applied to the internal electrode 5, a cooling medium having high electrical insulation is required. Generally, a refrigerant having a high electric insulation property is an organic substance, but the organic substance refrigerant is deteriorated by ultraviolet rays generated from a lamp. Therefore, distilled water having high electric insulation may be used, but in the case of distilled water, it is difficult to maintain and manage the electric insulation.

Therefore, in the present invention, the tube 3 having a high electric insulation property is used.
Is inserted in the substantially central portion of the hollow portion of the discharge vessel 1, and the refrigerant 10 is caused to flow inside the tube 3 having high electrical insulation.
That is, the internal electrode 5 is not directly cooled by the cooling medium, but the cooling medium is caused to flow through a pipe having high electric insulation to indirectly cool the internal electrode. As a result, a refrigerant such as distilled water having high electric insulation is not required. As a member of the tube with high electrical insulation,
Ceramics such as alumina and glass, which do not deteriorate due to ultraviolet rays and have good thermal conductivity, are suitable. Further, since the refrigerant does not require electrical insulation, water may be used as the refrigerant having a large specific heat.

Generally, in the excimer lamp, the higher the probability that the excited rare gas atom and the other atom meet, the higher the output efficiency of ultraviolet rays. Therefore, if the discharge gas pressure is increased, the output efficiency of ultraviolet rays is increased, but if the discharge gas pressure is too high, the discharge start voltage increases and it becomes difficult to light the lamp. Therefore, as in the electrodeless electric field discharge excimer lamp according to the present invention, if the lighting frequency of the lamp is high (radio frequency, 1 to 100 MHz), excited rare gas atoms and other atoms are generated even if the discharge gas pressure is low. The chances of encountering are high. In addition, since the discharge vessel is sufficiently cooled from the central portion of the lamp, the discharge gas is also cooled and the luminous efficiency of ultraviolet rays is further improved. Further, since the discharge gas pressure of the lamp is low, the discharge starting voltage becomes low, and the startability of the lamp is also improved.

[0019]

As described above, according to the present invention, in the electrodeless electric field discharge excimer lamp for applying a high frequency in the range of 1 to 100 MHz to the internal electrode as a lighting frequency to cause electric field discharge, the tip portion of the trigger electrode is used. Width A of 0.
By setting the distance B between the trigger electrode and the external electrode to 15 mm or less and 1 mm to 5.0 mm, there is an advantage that the starting lighting can be reliably performed. Further, by bending the front part of the trigger electrode and making it elastic and contacting the inside of the discharge vessel, there is no attenuation of the starting energy, and since a highly electrically insulating tube can be held inside the discharge vessel,
There are advantages such as easy manufacture of the lamp.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an electrodeless electric field discharge excimer lamp according to the present invention.

FIG. 2 is a plan view and a side view of a trigger electrode.

FIG. 3 is an explanatory diagram showing a positional relationship between a trigger electrode and an external electrode, similarly.

FIG. 4 is a characteristic diagram showing a relationship between an electrode distance between a trigger electrode and an external electrode and a starting voltage in an example of the present invention and a conventional example.

[Explanation of symbols]

1 discharge vessel 2 external electrodes 3 Tubes with high electrical insulation 4 Trigger electrode 5 internal electrodes 6 Trigger power supply 7 High frequency power supply 8 base (ceramic base for lamp mounting) 9 terminals (refrigerant outlet) 10 Refrigerant

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihisa Shibata             1-1 Iriyama-cho, Gyoda-shi, Saitama Iwasaki Electric Co., Ltd.             Inside the Saitama Factory

Claims (2)

[Claims] 1. A hollow discharge vessel filled with a discharge gas, an external electrode attached to the outside of the discharge vessel, and a hollow electrical insulating material inserted into a substantially central portion of the hollow portion of the discharge vessel. A high tube, a trigger electrode and an internal electrode attached to the outer surface of the tube having high electrical insulation, and an electrodeless field discharge excimer lamp for applying an electric field to the internal electrode by applying a high frequency in the range of 1 MHz to 100 MHz. There
The width A of the tip of the trigger electrode is 0.1 to 5.0 mm.
And an electrodeless electric field discharge excimer lamp, which is configured to be in contact with the inside of the discharge vessel. 2. The distance B between the trigger electrode attached to the outer surface of the tube having high electrical insulation and the external electrode attached to the outside of the discharge vessel is set to 15 mm or less. 1. The electrodeless electric field discharge excimer lamp according to 1.