JP2021051936A - Barrier discharge lamp and UV irradiation unit - Google Patents

Abstract

To provide a barrier discharge lamp having appropriate light emitting characteristics.SOLUTION: A barrier discharge lamp 1 includes a cylindrical arc tube 2, an internal electrode 3, an external electrode 7, and a heat dissipation block 8. The arc tube 2 is filled with gas and transmits ultraviolet light. The internal electrode 3 is arranged inside the arc tube 2 and extends in the tube axial direction of the arc tube 2. The external electrode 7 covers the arc tube 2 at an angle of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube 2. A heat radiating block 8 faces the arc tube 2 with the external electrode 7 interposed therebetween.SELECTED DRAWING: Figure 2

Description

Embodiments of the present invention relate to barrier discharge lamps and UV irradiation units.

Conventionally, barrier discharge lamps used for the purpose of cleaning and modifying substrates are known. The barrier discharge lamp is a dielectric barrier discharge generated by connecting a spiral internal electrode arranged inside the arc tube, which is a dielectric, and an external electrode arranged outside the arc tube to an AC power source. It emits ultraviolet light having a specific wavelength according to the gas contained inside the arc tube.

Japanese Unexamined Patent Publication No. 2013-21164

In the barrier discharge lamp as described above, proper light emission characteristics may not be obtained depending on, for example, the dimensions of the external electrodes.

An object to be solved by the present invention is to provide a barrier discharge lamp and an ultraviolet irradiation unit having appropriate light emitting characteristics.

The barrier discharge lamp of the embodiment includes a cylindrical arc tube, an internal electrode, an external electrode, and a heat dissipation block. The arc tube is filled with gas and transmits ultraviolet light. The internal electrode is arranged inside the arc tube and extends in the axial direction of the arc tube. The external electrode covers the arc tube at an angle of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube. The heat dissipation block faces the arc tube with an external electrode in between.

According to the present invention, it is possible to have appropriate light emission characteristics.

It is a figure which shows the ultraviolet irradiation unit which concerns on embodiment. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is a figure which shows the result of the evaluation test 1. It is a figure which shows the result of the evaluation test 2.

The barrier discharge lamp 1 according to the embodiment described below includes a cylindrical arc tube 2, an internal electrode 3, an external electrode 7, and a heat dissipation block 8. The arc tube 2 is filled with gas and transmits ultraviolet light. The internal electrode 3 is arranged inside the arc tube 2 and extends in the tube axial direction of the arc tube 2. The external electrode 7 is provided on the outer surface 2b side of the arc tube 2 so as to face the internal electrode 3, and covers the arc tube 2 at an angle θ7 of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube 2. .. The heat radiating block 8 faces the arc tube 2 with the external electrode 7 interposed therebetween.

Further, the external electrode 7 according to the embodiment described below has a thickness t of more than 0 [mm] and 1.0 [mm] or less.

Further, the ultraviolet irradiation unit 100 according to the embodiment described below includes one or more barrier discharge lamps 1.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The embodiments shown below do not limit the techniques disclosed by the present invention.

[Embodiment]
FIG. 1 is a diagram showing an ultraviolet irradiation unit according to an embodiment, and FIG. 2 is a sectional view taken along the line AA of FIG. As shown in FIGS. 1 and 2, the ultraviolet irradiation unit 100 according to the embodiment has one or more barrier discharge lamps 1, an external electrode 7, and a heat dissipation block 8.

For the sake of clarity, FIGS. 1 and 2 show a three-dimensional Cartesian coordinate system including a Z-axis whose positive direction is the irradiation direction. Further, in FIG. 1, the heat dissipation block 8 is not shown.

The barrier discharge lamp 1 performs barrier discharge with an external electrode 7 provided on the outer surface side of the barrier discharge lamp 1. In the present embodiment, the external electrode 7 is provided on the outer surface side of the barrier discharge lamp 1, but the barrier discharge lamp 1 and the external electrode 7 are combined, and more specifically, the arc tube 2 described later. The form in which the external electrode 7 is combined may be referred to as a "barrier discharge lamp", and the form in which the barrier discharge lamp 1, the external electrode 7 and the heat dissipation block 8 are combined may be referred to as a "barrier discharge lamp". Good.

As shown in FIGS. 1 and 2, the barrier discharge lamp 1 has a light emitting tube 2, an internal electrode 3, a reflective film 4, a base 5, and a lead wire 6. The arc tube 2 is a cylindrical member that transmits ultraviolet light. Examples of the material of the arc tube 2 include synthetic quartz having a wavelength of 200 [nm] or less and a high vacuum ultraviolet transmittance. Specifically, for example, Shinetsu quartz synthetic quartz F-310 can be used as the material for the arc tube 2. Further, the arc tube 2 is hermetically sealed by being held by sealing members having a stem structure at both ends in the tube axis direction (X-axis direction).

Further, gas is sealed inside the arc tube 2. The gas is, for example, 80 to 200 [kPa] xenon gas. Specifically, for example, 93 [kPa] xenon gas is filled inside the arc tube 2. The gas may be composed of, for example, one type of krypton, xenon, argon, neon, etc., or a combination of a plurality of types. Further, the gas may include, for example, a halogen gas, if necessary. The arc tube 2 can emit ultraviolet light (excimer light) having a specific peak wavelength according to the type of the enclosed gas. In the application of cleaning the surface of the glass for a liquid crystal panel, for example, an arc tube 2 that emits vacuum ultraviolet light having a wavelength of 172 [nm] can be used.

The internal electrode 3 is arranged inside the arc tube 2. In the internal electrode 3, a coil portion 3a, which is a spiral conductor, extends in the tube axis direction of the arc tube 2. The internal electrode 3 is formed of, for example, a material containing tungsten. Specifically, the internal electrode 3 contains tungsten as a component of 50 [%] or more of all the components. In particular, when doped tungsten obtained by adding potassium or the like to tungsten is applied as the internal electrode 3, higher dimensional stability can be obtained. Specifically, for example, potassium-doped tungsten WK75 manufactured by Pluse can be used as a material for the internal electrode 3.

Further, the wire diameter φ of the internal electrode 3 can be, for example, 0.5 [mm] or more and 1.0 [mm] or less. Further, for the internal electrode 3, for example, the distance P in the tube axis direction of the coil portion 3a can be set to, for example, 10 [mm] or more and 50 [mm] or less. Specifically, for example, the internal electrode 3 in which the distance P between the coil portions 3a is 30 [mm] can be used.

The reflective film 4 is provided on the inner surface 2a of the arc tube 2 and reflects ultraviolet light into the arc tube 2. Examples of the material of the reflective film 4 include silica. Further, the reflective film 4 is not limited to silica, and may be made of a material containing ultraviolet scattering particles such as alumina. The reflective film 4 is arranged at an angle θ4 of 180 [°] or more, for example, 200 [°] or more and 300 [°] or less in the circumferential direction of the arc tube 2. Further, the length L4 of the reflective film 4 in the tube axis direction is arranged so as to be equal to or longer than the length L3 of the coil portion 3a of the internal electrode 3 in the tube axis direction. As a result, the decrease in luminous efficiency can be suppressed by efficiently irradiating the irradiated body with the ultraviolet light generated in the arc tube 2.

Further, the reflective film 4 is formed so as to have a film thickness of, for example, 100 [μm] or more and 300 [μm] or less from the viewpoint of maintaining good reflectance. The reflective film 4 may be in contact with or separated from the coil portion 3a of the internal electrode 3. However, as the barrier discharge lamp 1 according to the modified example of the embodiment, a mode in which the reflective film 4 is not provided is also allowed.

The external electrode 7 is provided on the outer surface 2b side of the arc tube 2 corresponding to the inner surface 2a of the arc tube 2 provided with the reflective film 4. The external electrode 7 can be made of, for example, stainless steel or aluminum.

The external electrode 7 is arranged at an angle θ7 of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube 2. If the angle θ7 is less than 180 [°], the contact area with the arc tube 2 is small, so that the ultraviolet illuminance is reduced and proper emission characteristics cannot be obtained. Further, when the angle θ7 exceeds 300 [°], the emitted ultraviolet light interferes with the external electrode 7 before reaching the irradiated body, and proper light emission characteristics cannot be obtained. Therefore, the angle θ7 of the external electrode 7 is set to 180 [°] or more and 300 [°] or less.

Further, the thickness t of the external electrode 7 is formed so as to be, for example, more than 0 [mm] and 1.0 [mm] or less, particularly 0.2 [mm] or more and 0.8 [mm] or less. When the thickness t exceeds 1.0 [mm], the fitability between the arc tube 2 and the external electrode 7 is lowered, and a gap is likely to be formed between the outer surface 2b of the arc tube 2 and the external electrode 7. , Proper light emission characteristics may not be obtained.

The heat dissipation block 8 is arranged so as to face the arc tube 2 with the external electrode 7 interposed therebetween, and dissipates heat from the heat-generating barrier discharge lamp 1. The heat dissipation block 8 can be made of, for example, aluminum or stainless steel. The heat dissipation block 8 may be provided with a flow path for flowing a liquid or gas refrigerant to further improve the heat dissipation. The inner surface 8a of the heat radiating block 8 and the outer surface 7a of the outer electrode 7 may be in contact with each other or separated from each other, but when the heat radiating block 8 and the outer electrode 7 are brought into contact with each other, the heat radiating property can be improved. .. Further, if necessary, the inner surface 8a and / or the end surface 8b of the heat dissipation block 8 may be subjected to an insulating treatment to cut off the conduction with the external electrode 7.

Further, in the example shown in FIG. 2, the angle θ7 of the external electrode 7 and the angle of the heat radiation block 8 that covers the outer surface 7a of the external electrode 7 in the circumferential direction of the arc tube 2 are shown to be the same. It is not limited to, and may be different from each other. In other words, the end portions 7b of the external electrodes 7 located at both ends in the circumferential direction of the arc tube 2 may protrude from the end surface 8b of the heat radiation block 8 toward the irradiated body side (Z-axis positive direction side), and may protrude from the end surface 8b. It may be immersed in the negative direction side of the Z axis.

The base 5 is arranged so as to cover one end side of the lead wire 6 and supports both ends of the arc tube 2 in the tube axial direction. The base 5 is formed using, for example, an insulating steatite. Further, the base 5 may be formed of an insulator such as aluminum oxide. The base 5 may be arranged so as to be in contact with the external electrode 7, or may be arranged apart from the external electrode 7.

The lead wire 6 is electrically connected to the internal electrode 3. Further, the lead wire 6 is drawn from a base 5 that supports both ends of the arc tube 2 in the tube axial direction, and is electrically connected to the external electrode 7 via a lighting device (not shown) connected to an AC power supply. A predetermined voltage can be applied between the electrodes to cause the arc tube 2 to emit light. The lighting device includes an inverter capable of outputting high voltage and high frequency, and is configured to be able to supply electric power from an AC power source to the barrier discharge lamp 1. The lighting device can, for example, apply a sine wave having a frequency of 37 kHz to light the barrier discharge lamp 1 with a lamp power of about 2.4 kW. The lead wire 6 is not limited to the configuration provided only on one end side of the arc tube 2 as shown in FIG. 1, and may be provided on both ends of the arc tube 2, for example.

[Evaluation test 1]
A lighting test was conducted using a prototype of a barrier discharge lamp, and the angle θ7 of the external electrode 7 covering the arc tube 2 in the circumferential direction was changed from 120 [°] to 360 [°] in 30 [°] increments to obtain ultraviolet rays. The effects on illuminance and power were evaluated respectively. FIG. 3 shows the result of the evaluation test 1. The ultraviolet illuminance [mW / cm ² ] was measured by bringing the illuminometer head VUV-S172 (manufactured by Ushio, Inc.) connected to the illuminometer main body UIT-250 (manufactured by Ushio, Inc.) into contact with the barrier discharge lamp. The electric power [W] is the power consumption of the barrier discharge lamp measured using the oscilloscope TDS3012B (manufactured by Tektronix). ^{In FIG. 3, the values of the ultraviolet illuminance [mW / cm 2} ] and the power [W] when the angle θ7 of the external electrode 7 is θ7 = 180 [°] are converted into the relative illuminance and the relative power where the values are 100 [%]. Each is shown. The thickness t of the external electrode 7 was 0.5 [mm].

As shown in FIG. 3, the relative illuminance was 100 [%] in the range where the angle θ7 was 180 [°] or more and 300 [°] or less, and it was confirmed that the relative illuminance had appropriate light emission characteristics. On the other hand, the relative illuminance could not be 100 [%] when the angle θ7 was less than 180 [°] and more than 300 [°].

Further, the relative power could be 100 [%] or more in the range where the angle θ7 was 180 [°] or more and 300 [°] or less. On the other hand, the relative power could not be 100 [%] or more when the angle θ7 was less than 180 [°]. From this, it is considered that the relative power could not be 100 [%] or more when the angle θ7 was less than 180 [°], so that the power did not enter the barrier discharge lamp and the relative illuminance became less than 100 [%]. Be done. On the other hand, when the angle θ7 exceeds 300 [°], the area covered by the external electrode 7 in the circumferential direction increases, and the ultraviolet rays emitted from the arc tube 2 are shielded by the external electrode 7, so that they are relative. It is considered that the illuminance was less than 100 [%]. From these results, the condition of the angle θ7 of the external electrode 7 capable of having appropriate light emission characteristics was confirmed. When the angle θ7 is 210 [°] to 300 [°], the relative illuminance is 100 [%] even though the relative power is over 100 [%], which is input to the arc tube 2. It is considered that this is because the power generated by the light emitting tube 2 and the area covered by the external electrode 7 in the circumferential direction are increased, and the effect that the ultraviolet rays emitted from the light emitting tube 2 are shielded by the external electrode 7 is offset.

[Evaluation test 2]
A lighting test was performed using a prototype of a barrier discharge lamp, and the thickness t of the external electrode 7 covering the arc tube 2 in the circumferential direction was changed from 0.2 [mm] to 1.2 [mm] to change the arc tube 2 The fitability with and the effect on power were evaluated respectively. FIG. 4 shows the results of the evaluation test 2.

The evaluation of the fitability is based on the fact that the external electrode 7 is not easily removed from the arc tube 2 and the adhesion between the arc tube 2 and the external electrode 7 as criteria. No problem in actual use, ×: The external electrode 7 was easily dropped off, and it was determined that there was a problem. The electric power [W] is measured using an oscilloscope TDS3012B (manufactured by Tektronix), and converted into a relative electric power in which the electric power value when the thickness t = 0.4 [mm] of the external electrode 7 is 100 [%]. Shown. The angle θ7 of the external electrode 7 was set to 236 [°].

As shown in FIG. 4, it was confirmed that the fitability had appropriate light emitting characteristics without any problem in actual use in the range where the thickness t was 0.2 [mm] or more and 1.0 [mm] or less. In particular, it was confirmed that in the range of the thickness t of 0.2 [mm] or more and 0.8 [mm] or less, the fitting property was good and the light emitting characteristics were more appropriate. Further, the relative power was 90 [%] or more in the range where the thickness t was 0.2 [mm] or more and 1.0 [mm] or less, and it was confirmed that the relative power had appropriate light emission characteristics. In particular, when the thickness t was in the range of 0.2 [mm] or more and 0.8 [mm] or less, the relative power was 100 [%], and it was confirmed that the material had more appropriate light emission characteristics. From these results, the condition of the thickness t of the external electrode 7 capable of having appropriate light emitting characteristics was confirmed.

As described above, the barrier discharge lamp 1 according to the embodiment includes a cylindrical arc tube 2, an internal electrode 3, an external electrode 7, and a heat dissipation block 8. The arc tube 2 is filled with gas and transmits ultraviolet light. The internal electrode 3 is arranged inside the arc tube 2 and extends in the tube axial direction of the arc tube 2. The external electrode 7 is provided on the outer surface 2b side of the arc tube 2 so as to face the internal electrode 3, and covers the arc tube 2 at an angle θ7 of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube 2. .. The heat radiating block 8 faces the arc tube 2 with the external electrode 7 interposed therebetween. As a result, it is possible to have appropriate light emission characteristics and ensure heat dissipation.

Further, the external electrode 7 according to the embodiment has a thickness t of more than 0 [mm] and 1.0 [mm] or less. Thereby, it is possible to have appropriate light emission characteristics.

Further, the ultraviolet irradiation unit 100 according to the embodiment includes one or a plurality of barrier discharge lamps 1. As a result, it is possible to have appropriate light emission characteristics and ensure heat dissipation.

Although embodiments of the present invention have been described, the embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

1 Barrier discharge lamp 2 Light emitting tube 3 Internal electrode 4 Reflective film 7 External electrode 8 Heat dissipation block 100 Ultraviolet irradiation unit

Claims (3)

With a cylindrical arc tube filled with gas and transmitting ultraviolet light;
With an internal electrode arranged inside the arc tube and extending in the tube axis direction of the arc tube;
An external electrode provided on the outer surface side of the arc tube so as to face the internal electrode and covering the arc tube at an angle of 180 [°] or more and 300 [°] or less in the circumferential direction of the arc tube;
With a heat dissipation block facing the arc tube across the external electrode;
A barrier discharge lamp. The barrier discharge lamp according to claim 1, wherein the external electrode has a thickness of more than 0 [mm] and 1.0 [mm] or less. An ultraviolet irradiation unit comprising one or a plurality of barrier discharge lamps according to claim 1 or 2.

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