JP4389682B2 - Excimer discharge lamp device - Google Patents

Description

  The present invention relates to a structure of an excimer discharge lamp device that performs dielectric barrier discharge.

  In recent years, a discharge vessel is formed by closing both ends of a cylindrical tube made of a dielectric, a rare gas such as xenon is sealed inside the discharge vessel, and a pair of electrodes disposed outside the discharge vessel with the dielectric interposed In between, excimer discharge that applies xenon temporarily in the enclosed space by applying a high frequency voltage of about 50 kHz, for example, temporarily turns xenon into an excimer state and emits ultraviolet rays when the energy level drops to the ground state Lamps are starting to be used as light sources for surface cleaning and surface modification of semiconductors and electronic components.

In a conventional excimer discharge lamp apparatus, a cross-sectional view in the tube axis direction is shown in FIG. 14, but a mesh-structured metal electrode 22 is used outside a discharge vessel 21 made of a dielectric such as quartz glass. In order to efficiently emit ultraviolet rays to the outside of the discharge vessel, a net-structured electrode is suitable and adopted. As the metal electrode 22, for example, monel metal, which is a nickel alloy, is used because of its high heat and corrosion resistance. Reference numeral 23 denotes an electrode facing the electrode having a net structure, and is made of a metal such as aluminum. Reference numeral 7 denotes a high-frequency power source as a lighting power source.
However, since the expansion rate of quartz glass, which is the discharge vessel 21, and that of the monel metal are different, metal powder is rubbed and the object is irradiated while the excimer discharge lamp is turned on. Become.

  An excimer discharge lamp enclosing xenon emits vacuum ultraviolet light of 172 nm. The vacuum ultraviolet light generates ozone in the air atmosphere, and the metal electrode having a net structure is oxidized and corroded. Oxidation of the external electrode causes a decrease in impedance and a decrease in the aperture ratio of the net, and there is a problem in that the lifetime of the lamp is affected as well as a decrease in luminous efficiency.

  Therefore, the excimer discharge lamp has a quartz glass irradiation window under the lamp so that an inert atmosphere with nitrogen is formed around the excimer discharge lamp and metal contamination does not fall on the irradiated object. The inside of the housing was purged with nitrogen.

  However, if there is an irradiation window made of quartz glass, it is unavoidable that the ultraviolet light attenuates while passing through the quartz glass, the irradiation window may be damaged, and the irradiation window is expensive. Therefore, an excimer discharge lamp apparatus in which the irradiation window is removed is desired in the industry.

By the way, it is possible to remove the irradiation window and blow nitrogen gas directly onto the excimer discharge lamp to oxidize and corrode the metal electrode of the network structure, but it has not been possible to completely prevent the oxidative corrosion of the electrode. Moreover, the above-mentioned metal contamination could not be prevented.
JP-A-6-310102

  SUMMARY OF THE INVENTION An object of the present invention is to provide an excimer discharge lamp device having a structure capable of performing stable dielectric barrier discharge without exposing an external electrode to the air atmosphere.

In order to solve the above-mentioned problem, the invention described in claim 1 is a discharge vessel made of a dielectric material in which a gas that generates excimer discharge is sealed, and a conductor that is fed from outside the discharge vessel and disposed in the discharge vessel. and Ri do because, consists of a excimer discharge lamp excimer discharge unit, which are more closely arranged on the outer surface of the discharge vessel having no electrodes, a lighting device for applying a voltage to the excimer discharge lamp, the point light device are those excimer discharge lamp apparatus characterized by excimer discharge between the conductors of the excimer discharge unit adjacent the through connected between the conductors of the excimer discharge unit adjacent the dielectric occurs.

  According to a second aspect of the present invention, in the excimer discharge lamp device according to the first aspect, the discharge vessel is tubular, and the conductor is disposed along substantially the center of the discharge vessel. To do.

  The invention according to claim 3 is the excimer discharge lamp device according to claim 2, wherein one of the adjacent excimer discharge units has a smaller outer diameter than the other excimer discharge unit. It is.

  The invention according to claim 4 is characterized in that one of the adjacent excimer discharge units has a thinner discharge vessel than the other excimer discharge unit. An excimer discharge lamp device is provided.

  According to the present invention, a stable dielectric barrier discharge can be performed without requiring an external metal electrode in the processing space (atmosphere). ADVANTAGE OF THE INVENTION According to this invention, it can be set as the excimer discharge lamp apparatus which does not produce the lifetime reduction of a lamp | ramp by the oxidation etc. of the electrode arrange | positioned outside the discharge vessel.

  In the present invention, when the excimer discharge unit of the unit constituting the excimer discharge lamp is disposed along the substantially center of the discharge vessel, each excimer discharge unit is arranged when a plurality of excimer discharge units are arranged in parallel. Discharge occurs substantially evenly across the conductor in the discharge unit.

  Further, when an excimer discharge lamp is configured by combining an excimer discharge unit, which is a discharge vessel having a small diameter, and an excimer discharge unit, which is a discharge vessel having a larger diameter and a larger wall thickness, a discharge start voltage can be lowered.

  In addition, when an excimer discharge lamp is configured by combining an excimer discharge unit, which is a thin-walled discharge vessel, and an excimer discharge unit, which is a larger-diameter and thick-walled discharge vessel, the discharge start voltage can be lowered.

In addition, according to the present invention, it is possible to provide an excimer discharge lamp device that has a simple structure and is inexpensive.

  Embodiments of the present invention will be described below. 1 and 2 are schematic sectional views of an excimer discharge lamp device 100 according to the first embodiment of the present invention. FIG. 1 shows an excimer discharge unit 10 which is a structural unit of the excimer discharge lamp of the present invention. Two excimer discharge units 10 in which xenon is sealed in a tubular quartz glass discharge vessel 1 at a pressure of 40 kPa to 80 kPa and conductors 2 are disposed through the discharge vessel 1 are made of a high dielectric constant such as alumina. A single excimer discharge lamp 50 is formed by interposing a spacer 3 made of the above material in between.

  Here, if the spacer 3 exists, the space | interval between the adjacent discharge containers 1 and 1 'can be ensured uniformly. The interval between the discharge vessels is about 2 mm. The thickness of the discharge vessel is 0.8 mm, for example, and the length in the tube axis direction is 2000 mm, for example. The sealing portion 4 of the discharge vessel 1 is sealed with a pinch seal using molybdenum foil 5. Stopped.

  In the present invention, the interval between each discharge vessel is sufficiently smaller than the gap interval inside the vessel, that is, the interval between the conductor and the inner wall of the discharge vessel, so that the external gap formed by the interval between each discharge vessel reaches the discharge start voltage. Therefore, it does not discharge outside the discharge vessel, it corresponds to a mere dielectric, and the amount of charge stored in the dielectric changes as the temperature rises, so the impedance changes due to the increase in the amount of electrons due to the temperature rise in the excimer discharge space. Therefore, a stable dielectric barrier discharge can be provided.

  For the conductor 2, a tungsten wire or the like is used in the discharge vessel 1. A tungsten wire is connected to one end of the molybdenum foil 5 in the sealing portion 4 of the discharge vessel 1, and the other end of the molybdenum foil 5 is connected to the conductor 2. A molybdenum rod led out as an external lead 6 is connected to the outside of the discharge vessel. The conductor 2 may be in the form of a coil or a plate in addition to the above-described linear shape, and as the metal, stainless steel, nickel alloy, monel metal, copper, molybdenum, etc. are suitable in addition to tungsten. Further, there may be a plurality of conductors in the same discharge vessel.

  The discharge vessel is not limited to a cylindrical shape, and the cross section perpendicular to the tube axis may be a square shape or other polygonal shapes. As the material, quartz glass, particularly synthetic quartz glass is preferable from the viewpoint of molding processability and ultraviolet light transmission characteristics, but single crystal alumina such as sapphire and polycrystalline alumina may also be used. The excimer discharge lamp of FIG. 2 is shown in FIG. 3, but the lead is not exposed from the sealing portion 4 and the sealing portion 4 is sandwiched by the power supply plate 6a from the outside of the sealing portion 4, and power is supplied by capacitive coupling. It is also possible.

Dielectric barrier discharge is performed by applying a high frequency of, for example, 50 kHz from the power source 7 between the conductors 2 and 2 'shown in FIG. FIG. 12 schematically shows the circuit configuration of the lighting device 7 of the excimer discharge lamp device according to the present invention. The lighting device 7 includes a converter unit 11, an inverter unit 12, and a step-up transformer 13. The converter unit 11 converts a commercial power source (not shown) into a DC power source, and the inverter unit 12 converts the DC power source into a high-frequency pulse. The voltage is supplied to the step-up transformer 13. The secondary side of the step-up transformer 13 has a structure with an intermediate tap 14, and the surface potential of the discharge vessel 1, 1 ′ of the excimer discharge lamp 50 is adjusted to a stable voltage.
Reference numerals 2 and 2 'denote conductors disposed in the discharge vessels 1 and 1', respectively.

In the excimer discharge lamp device 100 of FIG. 2, at the applied voltage frequency 20KHz～300kHz, a _{15V p-p} from _{5 kV p-p,} discharge excimer discharge between the conductor 2 and the conductor 2 'through a dielectric Arise. Here, although V _p-p shows an example of the voltage waveform in FIG. 13, it means the width of the maximum value (V _max ) and the minimum value ( _Vmin ) of the voltage waveform.

4 is a schematic cross-sectional view in a direction perpendicular to the tube axis direction of the excimer discharge unit of the excimer discharge lamp apparatus 100 of FIG. The discharge vessel L1 and the discharge vessel L2 are spaced apart by the spacer 3 at a distance of 1.5 mm or less. By setting the separation distance to 1.5 mm or less, the gap layer becomes a dielectric, and discharge in the discharge vessels L1 and L2 occurs without generating corona discharge in the gap layer. If the interval is longer than that, it will be difficult for the discharge to occur. The glass tubes of the discharge vessels L1 and L2 are 0.8 mm thick, the distance between the conductor A and the inner wall of the discharge vessel L1, and the distance between the conductor B and the inner wall of the discharge vessel L2 is 9.0 mm, and 80 kPa in the discharge vessels L1 and L2. Xenon is enclosed. The conductor is made of tungsten, and when a voltage of 10 kV is applied between the conductor A and the conductor B with the maximum and minimum width V _p-p of the voltage waveform, a discharge column H as shown in FIG. 4 is formed.

  As shown in FIG. 5, the excimer discharge units 10 are continuously arranged, the outermost side is a metal casing 16, the metal casing 16 is grounded, and the conductor of the excimer discharge unit adjacent to the casing 16 is between When a predetermined potential difference is generated, the discharge is performed also in the housing side space of the excimer discharge unit, and a discharge column H ′ is formed.

FIG. 6 is a schematic cross-sectional view perpendicular to the tube axis of an embodiment in which one adjacent excimer discharge unit has a smaller outer diameter of the discharge vessel and a thinner discharge vessel than the other excimer discharge unit. It shows with. The relatively large diameter discharge vessel L3 has a wall thickness of 0.8 mm, and the small diameter discharge vessel L4 has a wall thickness of 0.4 mm. Since the small-diameter excimer discharge unit has a short discharge gap and a small thickness, discharge of the excimer discharge unit starts at 6 kV with the maximum / minimum width V _{pp of the} voltage waveform. The large diameter discharge vessel L3 has an inner diameter of 14 mm, and the small diameter discharge vessel L4 has an inner diameter of 6 mm. In the discharge vessel L4, discharge starts at 2 kV to 4 kV, and when the voltage is further increased to 4 kv to 6 kV, discharge in the discharge vessel L3 occurs.

  Further, when the small-diameter excimer discharge unit having the discharge vessel L4 starts to discharge, ultraviolet rays emitted from the excimer discharge unit enter the excimer discharge unit having the adjacent large-diameter discharge vessel L3, and the discharge is easily started by photoelectrons. Easily discharges the large-diameter excimer discharge unit.

  FIG. 7 shows that a small-diameter excimer discharge unit having a discharge vessel L7 is positioned between two large-diameter excimer discharge units having discharge vessels L5 and L6 and below the center of the two large-diameter excimer discharge units. The arrangement is shown. When a voltage is applied between the conductor I and the conductor K and between the conductor K and the conductor J in this arrangement, the discharge column H faces obliquely downward, and if there is an object to be irradiated below the lamp, the discharge portion and the object to be irradiated The distance is reduced, and the irradiated object can be irradiated with high illuminance.

FIG. 8 shows a form in which the conductor is disposed in the tube member 8 in which at least one end made of a dielectric is opened in the discharge vessel. FIG. 9 shows a cross-sectional view in the tube axis direction. If the metal conductor is exposed in the discharge vessel, thermal electrons are emitted from the conductor, and the electric field is concentrated locally.
Since it discharges locally, when it sees in the tube axis direction, it may become unevenly distributed discharge. However, as shown in FIG. 8, the pipe members 8 and 8 'made of a dielectric are placed on the conductors M and N, and the pipe members 8 and 8' are covered.
It was found that the electric field distribution can be made uniform by discharging through the electrode and the discharge becomes stable. Small discharge columns h are also formed between the conductor M and the tube member 8 and between the conductor N and the tube member 8 '.

FIG. 10 shows an example of the structure of the excimer discharge unit 10 of the present invention. In FIG. 10A, a rod-shaped conductor 2 made of molybdenum or stainless steel having a diameter of 0.12 mm is disposed in the approximate center of the discharge vessel 1 in a discharge vessel made of quartz glass having a total length of 400 mm and a wall thickness of 0.8 mm. ing. The sealing end portion 17 is provided with a step seal that connects glasses having different expansion coefficients.
10B shows one end portion, the conductor 2 may be cantilevered by the recess 1a in the discharge vessel 1, and the conductor may be led out from one sealing portion.

  FIG. 11 shows another example of the structure of the excimer discharge unit 10 of the present invention. Molybdenum or stainless steel having a diameter of 0.12 mm is placed in a discharge vessel 1 made of quartz glass having a total length of 400 mm and a wall thickness of 0.8 mm. A coiled conductor made of is disposed substantially at the center of the discharge vessel. In order to hold the coil, the supporter 9 is arranged every 100 mm here. The supporter 9 is a metal wire having a diameter of 0.3 mm, or is made of an insulator such as glass. The sealing portion 4 is pinch sealed using a molybdenum foil 5. 6 is an external lead.

  In the above description, the excimer discharge lamp in which xenon is enclosed as the encapsulated gas has been described. For example, it is possible to take out ultraviolet light having different wavelengths from adjacent excimer discharge units by changing them individually.

The schematic sectional drawing of the excimer discharge unit of the excimer discharge lamp apparatus of this invention is shown. The schematic sectional drawing of the tube-axis direction of the excimer discharge lamp apparatus of this invention is shown. The example of the electric power feeding structure by capacitive coupling of the excimer discharge lamp apparatus of this invention is shown. 1 is a schematic sectional view perpendicular to the tube axis of an excimer discharge lamp of an excimer discharge lamp device according to the present invention. 1 is a schematic sectional view perpendicular to the tube axis of an excimer discharge lamp of an excimer discharge lamp device according to the present invention. The schematic sectional drawing perpendicular | vertical to the tube axis | shaft of the excimer discharge lamp of other embodiment of the excimer discharge lamp apparatus of this invention is shown. The schematic sectional drawing perpendicular | vertical to the tube axis | shaft of the excimer discharge lamp of other embodiment of the excimer discharge lamp apparatus of this invention is shown. 1 shows a schematic cross-sectional view perpendicular to the tube axis of an excimer discharge lamp of an excimer discharge lamp device . The schematic sectional drawing of the tube axis direction of the excimer discharge lamp of an excimer discharge lamp apparatus is shown. An example of the structure of the excimer discharge unit used for this invention is shown. The other example of the structure of the excimer discharge unit provided for this invention is shown. The structure of the lighting device of the excimer discharge lamp apparatus of this invention is shown. The example of the voltage waveform of the excimer discharge lamp apparatus of this invention is shown. The schematic sectional drawing of the tube axis direction of the conventional excimer discharge lamp apparatus is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'Discharge vessel 1a Recess 2, 2' Conductor 3 Spacer 4 Sealing part 5 Molybdenum foil 6 External lead 6a Feed plate 7 Lighting device 8, 8 'Tube member 9 Supporter 10 Excimer discharge unit 11 Converter part 12 Inverter part 13 Step-up transformer 14 Middle tap 16 Metal housing 17 Sealed end 21 Discharge vessel 22 Metal electrode 50 Excimer discharge lamp 100 Excimer discharge lamp devices L1, L2, L3, L4, L5, L6, L7, L8 Discharge vessels H, H ′ , H Discharge column A Conductor B Conductor C Conductor D Conductor E Conductor F Conductor G Conductor I Conductor K Conductor M Conductor N Conductor

Claims (4)

A discharge vessel made of a dielectric encapsulating gases produced an excimer discharge, Ri Do from the conductors arranged in the discharge vessel outside is powered from the discharge vessel, no electrode on the outer surface of the discharge vessel An excimer discharge lamp in which a plurality of excimer discharge units are arranged close to each other;
A lighting device for applying a voltage to the excimer discharge lamp,
The point light apparatus, excimer discharge lamp apparatus characterized by excimer discharge between the conductors of the excimer discharge unit adjacent the through connected between the conductors of the excimer discharge unit adjacent the dielectric occurs. 2. The excimer discharge lamp device according to claim 1, wherein the discharge vessel is tubular, and the conductor is disposed along substantially the center of the discharge vessel. The excimer discharge lamp device according to claim 2, wherein one of the adjacent excimer discharge units has a smaller outer diameter than the other excimer discharge unit. 4. The excimer discharge lamp device according to claim 2, wherein one of the adjacent excimer discharge units has a thinner discharge vessel than the other excimer discharge unit.

Images