JP2005209398A - Dielectric barrier discharge lamp, and ultraviolet-ray irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric barrier discharge lamp restrained from the generation of particles caused by the difference of thermal expansion, and provide an ultraviolet-ray irradiation device using the same. <P>SOLUTION: The dielectric barrier discharge lamp EXL comprises a slender tube-shaped airtight vessel 1 made of ultraviolet-ray transmissive material, an excimer generating gas sealed in the airtight vessel 1, a long inner electrode 2 arranged in the airtight vessel so as to generate the dielectric barrier discharge over whole axial direction, and an external electrode OE arranged on the outer face of the airtight vessel 1 with a gap of 0.05 to 1.0 mm along axial direction, acting so as to generate the dielectric barrier discharge in the airtight vessel 1 in cooperation with the inner electrode 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dielectric barrier discharge lamp and an ultraviolet irradiation apparatus using the same.

  Excimer discharge lamps or dielectric barrier discharge lamps, which generate silent near-monochromatic radiation by causing silent discharge or dielectric barrier discharge of rare gases such as xenon or rare gas halides, are described in many literatures. It has been known for some time. In the dielectric barrier discharge, a pulsed current flows. This pulsed current has a high-speed electron flow and has a long rest period. Therefore, when a substance that emits ultraviolet rays, such as xenon, temporarily binds to the molecular state (excimer state) and returns to the ground state. Efficiently emits short wavelength ultraviolet rays with little reabsorption. In the case of xenon, molecular light emission having a wide half-value width with a center wavelength of 172 nm is performed. The ultraviolet light having a wavelength of 172 nm has a larger energy than the ultraviolet light having a wavelength of 185 nm or 254 nm obtained from a low-pressure mercury lamp, and is larger than the binding energy of the organic compound to be decomposed. For this reason, by irradiating with ultraviolet rays having a wavelength of 172 nm, the bonds of the organic compound can be cut and decomposed and removed. Further, by performing ultraviolet irradiation with a wavelength of 172 nm in the atmosphere, oxygen in the atmosphere is decomposed to generate active oxygen, and the organic compound whose bond is broken reacts with the active oxygen to generate carbon dioxide (CO 2). And water (H 2 O) and the like are generated, so that the organic compound can be easily removed. Therefore, the dielectric barrier discharge lamp is extremely effective as an ultraviolet light source.

  As a dielectric barrier discharge lamp, a dielectric barrier discharge lamp that performs dielectric barrier discharge using an elongated tubular hermetic container is known (see Patent Document 1). By using an elongated dielectric barrier discharge lamp, it becomes possible to irradiate the irradiated object having a large area with ultraviolet rays.

  Further, it is a light transmissive and elongated tube, and a light transmissive external electrode is provided on the outer surface of the discharge vessel serving also as the first dielectric for dielectric barrier discharge, and the ratio L between the length L and the diameter D is provided on the inner side. A structure including an inner electrode made of a metal rod or metal pipe having / D of 30 or more has also been proposed (see Patent Document 2). By arranging the internal electrode and the external electrode along the tube axis direction of the elongated hermetic container, a relatively uniform ultraviolet illuminance distribution can be obtained in the tube axis direction.

  Further, there is a dielectric barrier discharge lamp that suppresses the drooping of the internal electrode by arranging the internal electrode by applying a tension or mounting the position regulator, that is, an anchor on the internal electrode. It has been developed by the present inventors (see Patent Document 3). By using such an internal electrode, the uniformity of the ultraviolet illuminance distribution in the tube axis direction is improved. According to Patent Document 3, since the anchor is made of a conductive metal, the anchor effectively acts as a part of the internal electrode to generate a dielectric barrier discharge with the external electrode. The distance between them is reduced, and the startability is improved.

  An arc tube having an elongated hermetic container as shown in Patent Documents 1 to 3, an internal electrode extending in the axial direction in the hermetic container, and an excimer-generating gas sealed in the hermetic container, and a cooling function The arc tube is recessed so that a part of the outer surface of the hermetic container fits, and the arc tube is pressed, and an external electrode made of foil-like aluminum is interposed therebetween, and By sandwiching between the lamp body and the hermetic container, the outer electrode is brought into close contact with the outer surface of the hermetic container to generate a uniform dielectric barrier discharge along the tube axis direction, and heat generated from the arc tube can be quickly generated. The light emission efficiency can be maintained in a high state by being diffused.

When ultraviolet irradiation is performed using the above-described conventional dielectric barrier discharge lamp of this type, a longer dielectric barrier discharge lamp has been developed with an increase in the area of the irradiated object, and its effective length is 1 m. More than that has been used.
JP-A-11-111235 JP-A-7-272692 JP 2001-084966 A

  However, if the dielectric barrier discharge lamp has a short lamp length of 500 mm or less, there is no problem with the structure in which the aluminum external electrode described above is sandwiched between the lamp body and the airtight container. It has been found that there are the following problems when the length is longer than 1 m, for example. In other words, each part is affected by expansion and contraction as the dielectric barrier discharge lamp blinks. The hermetic container of the dielectric barrier discharge lamp has a temperature of about 30 to several tens of degrees Celsius when turned on. On the other hand, the temperature rise of the lamp is suppressed due to cooling by the refrigerant. The external electrode, which is in close contact with the outer surface of the hermetic vessel, has a large coefficient of thermal expansion, so that when the dielectric barrier discharge lamp is turned on, the temperature increases as the temperature of the hermetic vessel rises and expands. It cools with temperature and shrinks. On the other hand, since the airtight container is made of a material having a relatively low coefficient of thermal expansion such as quartz glass, the expansion and contraction associated with blinking is small.

  Therefore, rubbing occurs between the hermetic container and the external electrode as the dielectric barrier discharge lamp blinks. When the lamp length exceeds 1 m, the positional deviation between the two becomes 1 mm or more. Then, the external electrode is scraped by this rubbing, and particles having a particle size of about 0.1 mm are likely to be generated. When such particles are generated, they adhere to the surface of the airtight container to form a black deposit, which affects the ultraviolet illuminance distribution, or the particles fall on the irradiated object and contaminate the irradiated object. .

  An object of this invention is to provide the dielectric barrier discharge lamp which suppressed generation | occurrence | production of the particle by a thermal expansion difference, and an ultraviolet irradiation device using the same.

  In addition, the present invention provides a dielectric barrier discharge lamp suitable for a long hermetic container and an ultraviolet irradiation device using the same, by easily maintaining a separation distance between the hermetic container and the external electrode within a predetermined range. The other purpose is to provide.

    The dielectric barrier discharge lamp according to the first aspect of the present invention is an airtight container having an elongated tubular shape made of an ultraviolet light transmissive material; an excimer-generating gas sealed in the airtight container; and a dielectric barrier discharge in the airtight container. A long internal electrode arranged to occur over almost the entire length in the tube axis direction; and on the outer surface of the hermetic vessel while forming a gap of 0.05 to 1.0 mm along the tube axis direction on the outer surface of the hermetic vessel And an external electrode that acts to cause dielectric barrier discharge in the hermetic container by cooperating with the internal electrode.

  In the present invention and each of the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

  <Regarding the Airtight Container> The airtight container is made of an ultraviolet light transmissive material, and has an elongated discharge space formed therein. For example, it can be set as the structure where the both ends of the elongate tube were sealed and the cylindrical discharge space was formed in the inside. Moreover, it can also be set as the structure where the cylindrical elongate discharge space was formed in the inside by sealing the both ends of a double elongate pipe | tube. Generally, synthetic quartz glass is used as a material that transmits ultraviolet rays. However, in the present invention, any material may be used as long as it is transparent to ultraviolet rays having a wavelength to be used.

  The diameter of the airtight container is not particularly limited, but the outer diameter is preferably 12 mm or more in order to increase the ultraviolet output. Further, the thickness can be set to 2 mm or less, preferably about 0.3 to 1 mm. On the other hand, the length of the airtight container is not limited at all, and can be set to any desired length according to the required ultraviolet irradiation length, that is, the effective length of the lamp. However, the present invention is particularly effective for a lamp having an effective length of 1 m or more, and can be a long body of about 2 m, for example.

  Further, the airtight container is preferably a straight straight pipe, but may be slightly curved. In practice, a slight curve is likely to occur when the elongated tube is formed. For example, a maximum of approximately 1 mm or less can be formed with respect to a total length of approximately 1200 mm. However, this degree of bending is allowed as being almost straight. As will be described later, when the spacer is disposed, when the hermetic container is curved in an arc shape as described above, the rear part of the arc is disposed so as to abut against the spacer. It becomes easy to regulate the separation distance between the electrodes within a predetermined range. In addition, if the cross-sectional shape of the tube is circular, the manufacturing cost is relatively low, which is preferable. However, if necessary, a desired cross-sectional shape such as an ellipse or a quadrangle can be adopted.

  Furthermore, the exhaust pipe can be connected to the hermetic container as a means for sealing the excimer generated gas after exhausting the inside of the hermetic container in the stage before sealing the hermetic container. In this case, the exhaust pipe can be connected to the side surface of the portion that is near one end of the airtight container and is exposed to the outside from the lamp body. After exhausting through the exhaust pipe, the excimer generated gas is sealed in the airtight container from the exhaust pipe, and the exhaust pipe is chipped off, thereby forming an exhaust tip-off portion, and the airtight container is hermetically sealed. . When exhaust is exhausted through an exhaust pipe formed at one end of the hermetic container, especially when the hermetic container is as long as 1 m or longer, there is a tendency that the time is somewhat longer for sufficient exhaust. Therefore, if necessary, a pair of exhaust pipes may be formed in the vicinity of both ends of the hermetic container, and exhaust may be performed simultaneously. Therefore, in this case, a pair of exhaust tip-off portions is formed.

  <Excimer Production Gas> As the excimer production gas, one or a mixture of rare gases such as xenon (Xe), krypton (Kr), argon (Ar), or helium (He) or a rare gas halide such as XeCl is used. , KrCl, or the like can be used. When the rare gas halide is sealed, the rare gas and a halogen such as fluorine, chlorine, bromine, or iodine may be sealed so that the halide is generated inside the hermetic container. In addition to the excimer-generating gas, a gas that does not generate excimer, such as neon (Ne), may be mixed in some cases.

  Furthermore, the excimer production gas can be sealed at a pressure of 20000 Pa or more. As the pressure increases, the lamp efficiency improves and the UV output increases. However, the lamp efficiency tends to saturate as the pressure increases.

  <Regarding Internal Electrode> The internal electrode is disposed so as to be located inside the outer surface of the airtight container. However, the internal electrode is not limited to a mode in which the internal electrode is inserted into the inside of the airtight container, and may be a mode in which the internal electrode is disposed outside, for example, inside the airtight container. In the case of the former mode, the internal electrode is exposed in the discharge space. In the latter case, for example, the airtight container has a double tube structure, and the internal electrode is disposed along a cylindrical wall surface formed on the central axis side of the airtight container. Therefore, in this invention, an internal electrode means that it is an electrode arrange | positioned relatively inside an airtight container, when an airtight container is seen from the outside.

  As can be understood from the above description, in the present invention, the internal electrode is disposed inside the hermetic container so as to generate a dielectric barrier discharge over substantially the entire length in the tube axis direction, that is, the entire effective length of the lamp. As long as it is a long electrode, the remainder may have any configuration. For example, various known configurations such as a coil shape, a rod shape, a plate shape, and a mesh shape can be selected and used as desired. Although the material which comprises an internal electrode is not specifically limited, For example, refractory metals, such as tungsten, molybdenum, and nickel, can be used. Tungsten and nickel have a relatively small work function and are easy to emit electrons, so that they are effective in reducing the starting voltage.

  Next, a preferred configuration example of the internal electrode will be described. That is, the internal electrode has a mesh shape in which a large number of unit mesh portions are arranged in the axial direction of the hermetic container via gaps, and is disposed in a state of being inserted into the hermetic container. It is equipped with the structure. By using this internal electrode, the amount of ultraviolet rays generated can be relatively increased. Note that “a large number of unit mesh portions are in the form of meshes arranged with gaps in the axial direction of the airtight container” means that the unit mesh portions are close to the inner wall surface of the airtight container and are airtight. Although it is spatially separated from each other in the axial direction of the container, it refers to a state where it is electrically connected. In addition, the unit mesh part may be continuous with respect to the circumferential direction, or may be divided. Therefore, specifically, the unit mesh portion is allowed to have, for example, a ring shape (the former mode), a spiral shape or a coil shape (the latter mode), or a mesh shape. In the case of a mesh shape, it belongs to the former or the latter depending on the configuration of the mesh.

  When the unit mesh portion has a ring shape, a plurality of unit mesh portions are connected at a predetermined pitch by providing a connecting portion extending in the axial direction of the hermetic container, and conductively Can be connected. In addition, by configuring the connecting portion so as to extend along the central axis of the hermetic container, the internal electrode as a whole is a filament for a copying halogen bulb having a large number of ring anchors (corresponding to unit mesh portions). Thus, the manufacturing equipment can be diverted and the manufacturing becomes easy. However, if necessary, a configuration in which the central axis of the hermetic container is removed and the connecting portion is directly connected to the ring portion of the mesh-like portion may be employed. The connecting portion may be a single straight line, or may have a coil shape whose outer diameter is 20% or less with respect to the inner diameter of the airtight container. Furthermore, the connecting portion can be sealed in a state in which an appropriate value of tension, preferably 2 kg or more, acts in the direction of the central axis. In order to apply the tension, it is convenient to form the internal electrode in a coil shape. Even if it is not coiled, tension in the central axis direction can be applied to the connecting portion. Regardless of the shape of the connecting portion, it is easy to apply tension to the connecting portion by sealing the both ends of the connecting portion to both ends of the airtight container. However, if necessary, the connecting portion is sealed to only one side of the hermetic container at one end, and the other end is fixed to the sealing portion by an appropriate means such as an anchor wire at the other end of the hermetic container. It is also possible to apply tension to the.

  On the other hand, when the unit mesh portion has a spiral shape or a mesh shape, the spiral or mesh portion also functions as a connecting portion, so that many unit mesh portions are mechanically and conductively connected to each other. Link. However, the shape retention of the internal electrode can be further imparted by welding a connecting portion made of a single or a plurality of rod-like bodies to a spiral or mesh unit mesh portion. Alternatively, when a spiral or mesh unit mesh portion is formed using a winding frame instead of the connecting portion of the rod-shaped body, the shape retention is improved. Note that the winding frame may be either insulating or conductive. If any of the above-described configurations is adopted for the mesh-like portion, the shape of the internal electrode can be given stability and the handling thereof can be facilitated. Further, the internal electrode is configured such that a product P · P of a pitch P (m) with respect to the axial direction of the unit mesh portion and a pressure p (Pa) of the excimer generation gas described later is within a predetermined range. . Further, as will be described later, even when the sealing pressure of the excimer generation gas is increased to improve the lamp efficiency, the distance between the unit mesh portion and the inner wall surface of the hermetic container can be 3 mm or less. If the distance is 3 mm or less, the discharge sustaining voltage can be suppressed to 1000 V or less under certain conditions.

  Next, a configuration example of the internal electrode disposed outside the airtight container will be described. That is, the airtight container has a double tube shape. The internal electrode is disposed on the outer wall surface of the inner tube portion formed on the tube axis side of the hermetic container. The internal electrode has a cylindrical shape and substantially abuts on the outer wall surface. The cylindrical portion of the internal electrode is formed using a plate material or a mesh material made of a conductive material. The external electrode is disposed on the outer wall surface of the outer tube portion of the airtight container. Therefore, in addition to the discharge space, the inner wall surface and the outer wall surface are interposed in series as a dielectric between the internal electrode and the external electrode.

  Next, a description will be given of a support structure and a power feeding structure when the internal electrode is disposed inside an airtight container made of quartz glass. In order to seal the internal electrode in the airtight container, a sealing structure using a sealing metal foil can be employed. That is, the end of the internal electrode is connected to the sealing metal foil by welding or the like, the internal electrode is inserted into the hermetic container, and then the quartz glass is pinch-sealed from above the sealing metal foil. If it does so, a sealing part will be formed in the edge part of an airtight container, and an internal electrode will be supported by a predetermined position.

  Further, in order to supply power to the internal electrode, a power supply unit that passes through the sealing portion of the hermetic container and is led out to the outside is disposed. The power supply unit constitutes a power supply end for supplying a current necessary for dielectric barrier discharge to the internal electrode. If desired, the inner end is connected to a plurality of locations including both ends dispersed along the tube axis direction of the internal electrode, and the outer end is connected to the outside of the hermetic container so that power is supplied simultaneously from a plurality of locations of the internal electrode. A plurality of derived power feeding units may be provided. Further, the power feeding section may be formed integrally with the internal electrode by extending the internal electrode, or a member prepared as a separate member may be connected to the internal electrode by means such as welding or caulking. . Further, the power feeding unit is allowed to have various shapes such as a linear shape, a rod shape, a button shape, and a pin shape.

  <Regarding External Electrode> The external electrode is 0.05 to 1.0 mm, preferably 0.1 to 0.9 mm along the tube axis direction on the outer surface of the airtight container at least in the effective length portion of the lamp. More preferably, it is arranged while forming a gap of about 0.5 ± 0.3 mm, is opposed to the internal electrode, and by cooperation of both electrodes, at least one wall surface of the hermetic container is made a dielectric. The dielectric barrier discharge is caused to occur in the hermetic container. It is assumed that the gap is formed over the entire region of the effective length of the lamp of the hermetic container. However, in the case where the spacer described later is used, since the spacer is made of a conductive metal, in the case of acting as an external electrode, contact with the spacer described later or close with a gap smaller than the above range. The part shall be excluded from the above conditions. The reason why the gap is limited to the range of 0.1 to 0.5 mm is as follows. That is, even if the gap is less than 0.1 mm, rubbing with the external electrode does not occur, but it becomes difficult to form a continuous gap in the tube axis direction of the hermetic container. This is because if the gap is less than 0.1 mm, it is difficult to form the gap because of the slight bending of the hermetic container that is difficult to avoid and manufacture. On the other hand, when the gap exceeds 0.5 mm, it is difficult to generate a stable dielectric barrier discharge, and it is necessary to apply a higher voltage to cause the dielectric barrier discharge. For this reason, the lighting circuit and the ultraviolet irradiation device are increased in cost. The gap is preferably formed by a space. However, if desired, the gap may be formed by an insulator within a range that does not undesirably affect the ultraviolet illuminance distribution along the tube axis direction on the surface in the irradiation direction of the hermetic container. It is allowed to be formed.

  In addition, in order to fix the space between the external electrode and the hermetic container, the both ends of the external electrode and the hermetic container are fixed to each other at the portion located on the end side away from the effective length of the lamp. can do. For this fixing, a part of the end of the external electrode is allowed to contact the outer surface of the airtight container. Even if the above contact causes an influence on the ultraviolet illuminance distribution along the tube axis direction on the irradiation side surface of the dielectric barrier discharge lamp, there is no problem because it is a portion other than the effective length of the lamp.

  Furthermore, the external electrode may have either a rigid configuration or a flexible configuration in the relationship of being spaced apart as described above. In the case of rigidity, an external electrode made of a conductive metal and having a block shape with a large heat capacity can be used. Therefore, a member conventionally referred to as a lamp can be used as it is as an external electrode if desired. In this case, it is not necessary to adopt a structure in which the conventionally used external electrode made of a thin aluminum plate is sandwiched between the lamp body and the airtight container. Further, in order to cool the hermetic container portion in the region where the dielectric barrier discharge occurs, a cooling means can be disposed on the external electrode. In this case, the cooling means may have any configuration, but it is preferable that a cooling pipe through which the refrigerant flows is attached to the external electrode. Furthermore, the external electrode may be in a continuous planar state or mesh state. The mesh shape means a mesh shape, a punching shape, a lattice shape, or the like.

  Furthermore, it is preferable that the external electrode has a curved surface that is concave so as to surround a substantial portion of the outer periphery of the hermetic container. As the curved surface of the external electrode, it is possible to select an angle range that surrounds the outer periphery of the hermetic container within a range of about 60 to 300 °, preferably 90 to 240 °, and most preferably 120 to 180 °. Therefore, the portion where the hermetic container is exposed to the outside without the external electrode is formed in an angle range obtained by subtracting the surrounding angle from 360 °, and ultraviolet light transmitted through the wall surface of the hermetic container is exposed to the exposed portion. It can be used for various purposes by irradiating from outside to outside and over a relatively long distance along the tube axis direction of the arc tube. Thus, when the external electrode surrounds a part of the angular range of the hermetic container, dielectric barrier discharge occurs only in a region where the external electrode is opposed, and the remaining region of the hermetic container acts as an ultraviolet transmission window. When the angle range in which the external electrode surrounds the hermetic container is in the range of about 90 to 240 °, a relatively large amount of ultraviolet rays is emitted by the dielectric barrier discharge, and the emitted ultraviolet rays are irradiated at a preferable angle. be able to. Moreover, when the surrounding range of the external electrode is within a range of 120 to 180 °, in addition to the above, assembly and disassembly between the external electrode and the airtight container and manufacture of the external electrode are facilitated. The curved surface of the external electrode may be ultraviolet reflective or non-reflective.

  Furthermore, the external electrode may be in either a mode that can be attached to or detached from the airtight container. The external electrode has a length in the tube axis direction so as to face the internal electrode. Then, dielectric barrier discharge can be caused along the tube axis direction of the arc tube.

  <Regarding the spacer> The spacer is preferably an intermediate part of the hermetic container, preferably in order to keep the distance from the hermetic container within a predetermined range along the tube axis direction of the hermetic container at least in the effective length portion of the lamp. Attached to the center. And any of a conductive substance and an insulating substance can be formed. As the conductive material, stainless steel (SUS) is preferable because it is difficult to cut. Further, as the insulating material, quartz glass, ceramics, and the like are preferable because they are not easily cut. In order for the spacer to regulate the distance between the external electrode and the hermetic container as necessary, the spacer is fitted and attached to a curved surface portion of the outer electrode on the hermetic container side, for example. However, when the spacer is made of a conductive material, it should be formed so that the width size in the tube axis direction of the spacer is 3 mm or less. Then, even if the spacer is disposed in a state of being electrically connected to the external electrode, the illuminance distribution in the tube axis direction does not change undesirably due to the strong dielectric barrier discharge generated around the spacer. It becomes like this.

  In addition, the spacer preferably includes a recess that fits and holds the outer periphery of the hermetic container in order to fix the position of the hermetic container to the external electrode. In order to achieve this, the spacer forms a recess in which the hermetic container is fitted by cutting out a part of the plate material, or by forming a recess in which the hermetic container is fitted by bending a ribbon-like metal member. It can be constituted by a member that has been lost. In the case of the spacer having the former configuration, a fitting groove perpendicular to the concave curved surface of the external electrode can be formed, and the spacer can be attached to the fitting groove. In the case of the spacer having the latter configuration, the spacer can be attached by sticking the curved spacer to the concave curved surface of the external electrode. The part of the spacer that faces the hermetic container is allowed to contact the outer surface of the hermetic container or to be spaced apart by forming a slight gap.

  Furthermore, the number of spacers is not particularly limited, but should be as small as possible within a range where the position of the hermetic container can be regulated as required. For example, if the airtight container is fixed or held to the external electrode including the holding by the spacer at intervals of about 500 to 800 mm as a guideline, the separation distance between the external electrode and the airtight container is within a predetermined range. It is certain to maintain.

    <Regarding the Action of the Present Invention> In the present invention, since the above-described configuration is provided, even if expansion or contraction occurs between the airtight container and the external electrode as the lamp blinks, at least the lamp No rubbing occurs between the effective length portions. For this reason, even if the effective length of the lamp exceeds 1 m, when the external electrode is rubbed, it is scraped to become fine particles and adheres to the outer surface of the hermetic container, or falls to transmit the transparent window of the ultraviolet irradiation device The occurrence of problems such as black deposits on the irradiated object when there is no transparent window is avoided.

  Further, since the separation distance between the hermetic container and the external electrode is regulated within the range of 0.05 to 1.0 mm, dielectric barrier discharge can be caused without difficulty. Therefore, the lighting circuit is also relatively simple in configuration.

  Furthermore, even if the effective length of the lamp exceeds 1 m, by arranging a spacer between the intermediate part of the hermetic container and the external electrode, the space between the hermetic container and the external electrode is 0.05-1. It becomes easy to separate within the range of 0 mm. In addition, by setting the thickness of the spacer in the tube axis direction to 3 mm or less, the degree of illuminance distribution in the tube axis direction can be maintained at a required level even if it is made of a conductive material. it can.

    An ultraviolet irradiation device according to a second aspect of the invention comprises: the dielectric barrier discharge lamp according to claim 1; an ultraviolet irradiation device main body provided with the dielectric barrier discharge lamp; a high-frequency lighting circuit for lighting the dielectric barrier discharge lamp; It is characterized by having;

  In the present invention, the “ultraviolet irradiation device” means any device that uses ultraviolet rays generated from a dielectric barrier discharge lamp device. For example, a semiconductor stepper, a photo-cleaning device, a photo-curing device, and a photo-drying device. The “ultraviolet irradiation device main body” means the remaining part of the ultraviolet irradiation device excluding the dielectric barrier discharge lamp unit and the high frequency generation means.

  Further, one or more dielectric barrier discharge lamps can be used as necessary.

  Furthermore, a high frequency lighting circuit is used to light the dielectric barrier discharge lamp. The high-frequency lighting circuit includes high-frequency generating means, generates a high-frequency voltage, and supplies high-frequency power necessary for the lighting to the dielectric barrier discharge lamp. “High frequency” refers to a frequency of 10 kHz or more. However, it is preferably 100 kHz to 2 MHz. The high-frequency lighting circuit preferably applies a high-frequency voltage of about 3000 V or less, preferably 1000 to 2500 V, when the dielectric barrier discharge lamp is stably lit. Furthermore, the starting voltage of the dielectric barrier discharge lamp is 2 to 6.0 kVp-p, and can be easily started by increasing the secondary open-circuit voltage of the high-frequency lighting circuit to the starting voltage. In this case, when a parallel inverter is mainly used as the high-frequency generating means, a high step-up ratio can be easily obtained, and the capacitance between the external electrode and the internal electrode of the dielectric barrier discharge lamp is, for example, the pressure contact state of the external electrode. Since the change does not affect the high frequency output even if it changes, it is preferable because the design of the high frequency lighting circuit becomes easy. Since the high frequency output waveform is a sine wave, noise generation is reduced when the dielectric barrier discharge lamp is turned on. However, if necessary, a starting pulse voltage generating means can be used together with the high-frequency lighting circuit. Furthermore, the dielectric barrier discharge lamp and the high-frequency lighting circuit are preferably disposed at close positions, but can be disposed at positions separated from each other if necessary. Unlike a general discharge lamp, a dielectric barrier discharge lamp does not require a current limiting means to be connected in series. However, in order to adjust the lamp current to a predetermined value, lighting with an appropriate value of impedance connected in series can be performed as necessary. In addition, when the dielectric barrier discharge lamp is connected to the high frequency lighting circuit, if the external electrode is grounded, noise generation is reduced.

  If the high frequency lighting circuit outputs a pulse voltage, the remaining configuration is not limited. For example, a rectangular wave pulse can be obtained by using a rectangular wave output inverter. However, the configuration may be such that a sine wave pulse is obtained using an inverter having a sine wave output.

  Thus, in the present invention, generation of black deposits due to friction between the external electrode and the airtight container from the dielectric barrier discharge lamp can be avoided, so that the synthetic quartz is interposed between the irradiated object and the dielectric barrier discharge lamp. Since there is no need to install a light projection window made of glass, there is no loss of ultraviolet light due to the light projection window, and the irradiation distance to the irradiated object can be shortened, so that the ultraviolet illumination can be increased and the cost can be reduced. be able to.

    According to the first aspect of the present invention, since the external electrode and the airtight container are separated within a range of 0.05 to 1.0 mm, the generation of particles accompanying the blinking of the lamp is suppressed. It is possible to provide a dielectric barrier discharge lamp in which a kimono is prevented from adhering to an airtight container or an irradiated object.

    According to invention of Claim 2, the ultraviolet irradiation device which has the effect of Claim 1 can be provided.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

    FIGS. 1 to 5 show a first embodiment for implementing a dielectric barrier discharge lamp according to the present invention. FIG. 1 shows the entire dielectric barrier discharge lamp scaled in the tube axis direction and a sectional view of an external electrode. FIG. 2 is a partially cutaway front view of the arc tube, FIG. 3 is a partially cutaway enlarged front view of the notched main portion showing the support portion and the power feeding portion of the arc tube, and FIG. 4 is a spacer. And FIG. 5 is a side sectional view of the enlarged main portion showing the intake means. In this embodiment, the dielectric barrier discharge lamp EXL includes the arc tube LT, the external electrode OE, the spacer S, and the intake means AA, and is energized from the high frequency lighting circuit HFI.

  <Luminescent tube LT> The arc tube LT includes an airtight container 1, a discharge medium, and a long internal electrode 2, and includes power supply portions 3A and 3B and a support portion 5 at both ends.

    (Airtight container 1) As shown in FIG. 2, the airtight container 1 is made of an ultraviolet light transmissive material, and is formed at, for example, both ends of an elongated circular hollow portion 1a having an outer diameter of 18 mm and an inner diameter of 16 mm and the hollow portion 1a. The sealing portion 1b is provided and has a length of 1300 mm. The sealing portion 1b has a pinch seal structure in which a molybdenum foil 1b1 is embedded. In the hollow portion 1a, an exhaust tip-off portion (not shown) can be formed so as to protrude from the side surface. Xenon is enclosed in the hollow portion 1a of the hermetic container 1 as an excimer production gas.

    (Long Internal Electrode 2) In the case of this embodiment, the long internal electrode 2 is disposed in the airtight container 1 in a coaxial relationship with the airtight container 1, as shown in FIG. It consists of a mesh portion 2b and both end straight portions 2c. Note that the internal electrode 2 is not shown in FIGS. The connecting portion 2a is mainly composed of a coil 2a having an outer diameter of 1.2 mm, for example, formed by winding a thin metal wire made of a tungsten wire having a wire diameter of 0.26 mm. The unit mesh portion 2b is made up of a large number of ring-shaped anchors arranged on the connecting portion 2a at a constant pitch of 15 mm, for example. Both end straight portions 2c are formed by extending both ends of the connecting portion 2a. And the internal electrode 2 welds the both-ends linear part 2c to the end of the molybdenum foil 1b1 of the sealing part 1b formed in the both ends of the airtight container 1, in the state which acted about 2 kg of tension. The connecting portion 2 a of the internal electrode 2 is extended by the action of tension while being mounted in the airtight container 1.

    (Feeding portions 3A and 3B) The feeding portions 3A and 3B each have a rod shape, and their inner ends are welded to molybdenum foils 1b1 embedded in sealing portions 1b formed at both ends of the airtight container 1, The base end protrudes from the sealing part 1b formed in the both ends of the airtight container 1 in the external tube axis direction. In addition, the power feeding units 3A and 3B are caulked and connected to the power feeding line 4 inside a support unit 5 described later. The feeder line 4 extends from the output end of the high frequency lighting circuit HFI.

    (Supporting part 5) As shown in FIG. 3, the supporting part 5 includes a bottomed cylindrical cap body 5a, a fastening ring 5b, and a mounting arm 5c. The cap body 5a surrounds the end of the arc tube LT. And it has the insertion hole 5a1 of the feeder 4 at the bottom. The tightening ring 5 b is disposed at the opening end of the cap body 5 a and is fixed to the end of the airtight container 1. The mounting arm 5c protrudes upward in the figure from the side surface of the cap body 5a, and the arc tube LT is attached to the positioning guide 8 shown in FIG. The positioning guide 8 extends from both ends of the external electrode OE in the tube axis direction toward the end of the hermetic container 1 and defines the mounting position of the hermetic container 1.

  <External Electrode OE> As shown in FIGS. 1, 3 to 5, the external electrode OE is made of an aluminum block having a bottom surface formed into a concave arcuate curved surface and facing the internal electrode 2. Over the almost entire length of the region to be closed, the airtight container 1 is arranged to face the outer surface of the upper half of the hermetic container 1 with a gap G of 0.35 ± 0.15 mm. In addition, a cut groove 6 and a suction hole 7 for accommodating a spacer S, which will be described later, are formed in the central portion of the external electrode OE in the tube axis direction, and cooling pipes 8 are provided on both sides as shown in FIG. Welded. As shown in FIGS. 4 and 5, the cut groove 6 is formed so as to be orthogonal to the tube axis, and opens on the lower surface of the external electrode OE. The intake hole 7 is formed across the cut groove 6 and penetrates the upper and lower sides of the external electrode OE.

  <Spacer S> As shown in FIGS. 4 and 5, the spacer S is made of a stainless steel plate having a thickness of 3 mm, and is housed by press-fitting into the cut groove 6 of the external electrode OE, and the lower portion of the external electrode OE. It protrudes slightly from the arcuate curved surface located on the lower surface. The protruding amount is a value such that the gap G between the external electrode OE and the airtight container 1 does not become smaller than a predetermined separation distance. The spacer S and the airtight container 1 are slightly separated from each other in the drawing, but may be in contact with each other.

  <Intake Unit AA> As shown in FIGS. 4 and 5, the intake unit AA includes an intake hole 7 and an exhaust duct (not shown). Since the intake hole 7 is formed across the cut groove 6 as described above, the opening end of the lower end is divided and opened on both sides of the spacer S. For this reason, the air on both sides of the spacer S is satisfactorily taken into the intake holes 7. Then, the air discharged to the outside of the external electrode OE through the inside of the intake hole 7 is further discharged to the outside of the ultraviolet irradiation device by the exhaust duct. Therefore, even if the spacer S and the airtight container 1 are rubbed to scrape the spacer S to generate fine particles, the particles are quickly discharged to the outside together with the surrounding air by the air intake means AA. .

  <High Frequency Lighting Circuit HFI> The high frequency lighting circuit HFI applies a high frequency voltage between the internal electrode 2 and the external electrode OE of the dielectric barrier discharge lamp EXL to energize the dielectric barrier discharge lamp EXL to light it. . The high-frequency lighting circuit HFI is mainly configured by a parallel inverter, and the high-frequency output is supplied to the pair of power feeding portions 3A of the arc tube LT in the dielectric barrier discharge lamp EXL via the pair of power feeding lines 4 and 4. 3B and the external electrode OE are connected.

  <Lighting Operation of Dielectric Barrier Discharge Lamp EXL> The dielectric barrier discharge lamp EXL includes a pair of high frequency output terminals of the high frequency lighting circuit HFI led out from the internal electrode 2 via the feeder lines 4 and 4. Since it is connected to the power feeding units 3A and 3B and the other is connected to one end of the external electrode OE via the power feeding line 4, when an input power source (not shown) of the high frequency lighting circuit HFI is turned on, a high frequency is generated. A high frequency output is applied between the internal electrode 2 and the external electrode OE opposed to the internal electrode 2 via the wall surface of the hermetic container 1, and dielectric barrier discharge occurs inside the hermetic container 1. By this dielectric barrier discharge, vacuum ultraviolet light having a center wavelength of 172 nm is emitted by the xenon excimer. Since vacuum ultraviolet light permeate | transmits the wall surface of the airtight container 1, and is derived | led-out outside, this can be utilized according to each objective.

    FIG. 6 is a side sectional view showing a second embodiment for implementing the dielectric barrier discharge lamp of the present invention. In this embodiment, the arc tube LT of the dielectric barrier discharge lamp EXL is different.

  That is, in the arc tube LT, the airtight container 1 has a double tube structure, and the internal electrode 2 is disposed on the outer surface inside the airtight container 1. The airtight container 1 has a cylindrical discharge space formed inside. The internal electrode 2 is formed of a cylindrical mesh structure, and is disposed in close contact with the outer surface of the airtight container 1 that forms a cylindrical shape inside the airtight container 1. The external electrode OE has the same configuration and arrangement with respect to the airtight container 1 as in the first embodiment.

    7 to 10 show an ultraviolet cleaning device as one embodiment for carrying out the ultraviolet irradiation device of the present invention. FIG. 7 is a front sectional view, FIG. 8 is a bottom view, and FIG. 9 is IX-IX in FIG. FIG. 10 is a circuit diagram of the high-frequency lighting circuit. In each figure, the same parts as those in FIGS. The ultraviolet irradiation device UVW includes an ultraviolet irradiation device main body 51, a high frequency lighting circuit 52, and a plurality of dielectric barrier discharge lamps EXL.

  The ultraviolet irradiation apparatus main body 51 has a box shape as a whole, and the interior is divided into an ultraviolet irradiation chamber 51a and a power supply chamber 51b in the vertical direction. The ultraviolet irradiation chamber 51a and the power supply chamber 51b are configured such that one end thereof can be opened and closed by a hinge 51c.

  As will be described later, a plurality of dielectric barrier discharge lamps EXL are arranged in parallel in the ultraviolet irradiation chamber 51a. The plurality of dielectric barrier discharge lamps EXL have their external electrodes formed as a single block. Therefore, a plurality of concave curved surfaces of the external electrode OE are arranged in parallel in an adjacent state. Further, the ultraviolet irradiation chamber 51a is fixedly disposed above the irradiation object transporting means in the cleaning device, and the irradiation object (not shown) that has a lower surface open and passes directly below the lower surface. It is configured to irradiate vacuum ultraviolet light at a very close position. In FIG. 8, the shaded portion indicates the ultraviolet effective irradiation region. Further, although not shown, an exhaust collection box communicating with the intake holes of each dielectric barrier discharge lamp EXL is disposed on the upper surface of the integrated external electrode of the plurality of dielectric barrier discharge lamps EXL. The exhaust duct is connected through the exhaust collection box. The air around the spacer S of the airtight container 1 sucked from the intake hole via the exhaust duct is exhausted to the outside.

  The power supply chamber 51b houses therein a high-frequency lighting circuit 52 and a control circuit (not shown), and is rotatable upward in FIG. 7 with a hinge 51c as a rotation center. In addition, 51b1 is a handle for gripping the power supply chamber 51b during rotation, 51b2 is a handle for transporting the ultraviolet irradiation apparatus main body 51 or the power supply chamber 51b, and 51b3 is a protector for the power supply wiring.

  The high frequency lighting circuit 52 is housed in the power supply chamber 51b, converts the power introduced into the power supply chamber 51b via the power supply wiring protector 51b3, generates a high frequency voltage, and a plurality of dielectric barrier discharge lamps. Power is supplied to each dielectric barrier discharge lamp device of the device unit EX.

  The high frequency lighting circuit 52 has a circuit configuration shown in FIG. That is, the high-frequency lighting circuit 52 is mainly composed of an inductor L, a pair of switching elements Q1 and Q2, an output transformer OT, a resonance capacitor C1, and a control circuit CC, and includes DC input terminals t1 and t2, and high-frequency output terminals t3 and t4. This is a parallel inverter provided. The DC input terminals t1 and t2 are connected to a DC power source (not shown) whose output DC voltage is variable by a boost chopper circuit or the like. The high frequency output terminals t3 and t4 are connected to a dielectric barrier discharge lamp.

  The DC input terminal t1 is connected to the midpoint of the primary winding pw1 of the output transformer OT via an inductor L in series. The DC input terminal t2 is connected to the connection point of the pair of switching elements Q1 and Q2. The pair of switching elements Q1, Q2 are connected in series and are connected in parallel to the primary windings pw1, pw2, pw3 of the output transformer OT. The output transformer OT includes three sets of primary windings pw1, pw2, and pw3, three sets of secondary windings sw1, sw2, and sw3, a drive winding fw, and a detection winding dw. The primary windings pw1, pw2, and pw3 and the secondary windings sw1, sw2, and sw3 make a pair. The primary windings pw1, pw2, and pw3 are connected in parallel to each other. On the other hand, the secondary windings sw1, sw2, and sw3 are connected in series with each other and both ends thereof are connected to the high-frequency output terminals t3 and t4. The resonant capacitor C1 is connected in parallel to the primary windings pw1, pw2, and pw3. The drive winding fw and the detection winding dw are connected to a control circuit CC described later.

  The control circuit CC includes a drive circuit DC and a protection circuit PC. The input end of the drive circuit DC is connected to the drive winding fw, generates a drive signal, and supplies it to the switching elements Q1, Q2. Thereby, the parallel inverter self-oscillates. When the input end of the protection circuit PC is connected to the detection winding dw and the start of the dielectric barrier discharge lamp EXL is detected, the high-frequency output voltage is reduced by controlling the DC power source, for example.

  Thus, the high-frequency lighting circuit 52 has the above-described circuit configuration, so that the dielectric barrier discharge lamp EXL is started and lit. Then, the detection voltage appearing in the detection winding dw of the output transformer OT is monitored by the protection circuit PC, and when the high frequency output voltage rises after the start, the voltage applied to the switching elements Q1 and Q2 is lowered and reduced. A protective operation can be performed so as not to exceed the breakdown voltage. Further, the drive signal output from the drive circuit DC can be adjusted in accordance with the degree of high frequency output.

  By the way, the plurality of dielectric barrier discharge lamp device units EX are arranged adjacent to each other in the ultraviolet irradiation chamber 51a. However, each of the required dielectric barrier discharge lamp device units EX can be attached and detached for ease of manufacture and maintenance.

  Further, in order to allow the cooling water to flow through the cooling pipe of the external electrode OE, a pipe for supplying the cooling water is connected to the inlet, and a pipe for drainage is connected to the outlet.

1 is a front view of a dielectric barrier discharge lamp according to a first embodiment for implementing a dielectric barrier discharge lamp according to the present invention, wherein the entire dielectric barrier discharge lamp is reduced in the tube axis direction, and external electrodes are cross-sectionally shown together with a high-frequency lighting circuit. Similarly, partially cutaway front view of arc tube Similarly, a partially cutaway cross-sectional enlarged front view showing a support portion and a power feeding portion of the arc tube Similarly enlarged front sectional view showing the spacer and the intake means Same side sectional view Side surface sectional view which shows the 2nd form for implementing the dielectric barrier discharge lamp of this invention Front sectional drawing which shows the ultraviolet-ray cleaning apparatus as one form for implementing the ultraviolet irradiation device of this invention Similarly bottom view Similarly, a sectional view taken along line IX-IX 'in FIG. Similarly, high-frequency lighting circuit diagram

Explanation of symbols

      DESCRIPTION OF SYMBOLS 1 ... Airtight container, 2 ... Internal electrode, 4 ... Feeding line, 5 ... Holding part, 7 ... Intake hole, 8 ... Positioning guide, AA ... Intake means, EXL ... Dielectric barrier discharge lamp, G ... Gap, HFI ... High frequency lighting circuit, LT ... arc tube, OE ... external electrode, S ... spacer

Claims (2)

An airtight container having an elongated tubular shape made of a material that transmits ultraviolet light;
An excimer-producing gas enclosed in an airtight container;
A long internal electrode arranged so that a dielectric barrier discharge occurs in the hermetic vessel over substantially the entire length in the tube axis direction;
It is disposed on the outer surface of the hermetic container while forming a gap of 0.05 to 1.0 mm along the tube axis direction, and acts to generate a dielectric barrier discharge in the hermetic container by cooperating with the internal electrode. An external electrode;
A dielectric barrier discharge lamp comprising: A dielectric barrier discharge lamp according to claim 1;
An ultraviolet irradiation device body provided with a dielectric barrier discharge lamp;
A high-frequency lighting circuit for lighting a dielectric barrier discharge lamp;
An ultraviolet irradiation device comprising:

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