JP2010257875A - Discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excimer lamp with good startability which can be instantaneously lighted in various using conditions. <P>SOLUTION: The excimer lamp includes a pair of electrodes disposed oppositely on or in the vicinity of the outer surface of a discharge glass vessel, xenon gas sealed within the vessel, a dent or neck portion disposed partially or entirely on the circumference of the vessel to reduce the discharge space distance for enhancing the startability. Metal tantalum is held on the inner surface of the vessel at the site where the dent or neck portion is disposed, the metal tantalum playing a role as a getter to impurity gas within the vessel, and working as an auxiliary electrode for starting pulse. The outside main electrode is disposed on the outer surface of the vessel including the dent or neck portion, and the starting electrode is disposed at least on or in the vicinity of the outer surface of the vessel at the site facing the apex of the dent or neck portion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In particular, the present invention provides a startability of an electric field coupled discharge lamp, that is, an E discharge lamp (so-called excimer lamp), in which an electrode is disposed outside a glass container filled with a discharge gas and a high frequency voltage is applied to the electrode. Regarding improvements.

  In general, such a discharge is composed of a field-coupled electrodeless discharge in a glass container usually made of a synthetic quartz tube filled with a rare gas such as neon, argon, xenon, or krypton. The present invention is used for the construction of an excimer lamp that emits excimer light by applying an electrodeless discharge as disclosed. In particular, an excimer lamp filled with xenon gas has a radiation spectrum distribution with a center wavelength of 172 nm and a half-value width of 14 nm, and is higher than ultraviolet light with wavelengths of 185 nm and 254 nm emitted from a low-pressure mercury lamp that is widely used in general. Since it has energy, it can generate active oxygen and ozone with high efficiency, and has been used for glass cleaning of liquid crystal elements and PDP elements, or surface processing of silicon wafers of semiconductor substrates.

  In recent years, with the increase in the size of glass substrates used, higher cleaning efficiency has been demanded, and high output of such excimer light is desired. As a method for achieving such high illuminance, conventionally, the high frequency input power is increased within an energy range in which excimer light is emitted, that is, a range in which visible light emission does not increase, or a hollow cylindrical lamp as shown in FIG. Optimization of the dimensions of the outer tube 1a and the inner tube 1b of the body 1 and further optimization of the pressure of the rare gas to be sealed are performed.

  In general, such an excimer lamp is lit by a high frequency power supply of several MHz, so increasing the high frequency input power is considered when considering the withstand voltage performance and cost of circuit elements such as transistors incorporated in the high frequency power supply. Constraints are born naturally.

  On the other hand, by selecting the dimensions of the outer tube 1a and the inner tube 1b of the lamp body 1 having the hollow cylindrical structure shown in FIG. 1 so that the discharge space distance d1 is increased, or increasing the pressure of the rare gas to be enclosed. By doing so, it is possible to achieve high illuminance, but there is a disadvantage that the starting voltage for starting the electric field coupled electrodeless discharge becomes high.

  On the other hand, according to Patent Document 1, the inter-electrode distance (main discharge space distance) in the main discharge region is increased by disposing dents or constrictions in a part or the entire circumference of the glass container filled with the discharge gas. Succeeded in lowering the starting voltage for starting the field-coupled electrodeless discharge by shortening the distance between the electrodes in the starting discharge area (shortest discharge spatial distance) while maintaining the illuminance at the length that is realized. is doing. However, in a use environment where instantaneous lighting under various conditions is required, the conventional lamp still has a problem that the starting time is still too long and the variation is large, and sufficient reliability for starting cannot be secured.

JP 2004-227820 A

"Technical Trends of Electrodeless Discharge Lamps / Explanation of Electric Field Coupled Discharge E Discharge", Journal of the Illuminating Society of Japan, Vol. 77, No. 5, page 21 (1993) O plus E, Vol. 22, no. 8,1022-1024 pages (2000)

  The present invention has been made under such circumstances, and an object thereof is to provide an excimer lamp having good startability even under various conditions.

The discharge lamp of the present invention is
A glass container having a portion in which at least a part of the vessel wall faces each other, and a portion in which a dent or constriction is disposed on a part or the entire circumference of the outer surface (hereinafter referred to as “dent or constricted portion”), and the container A discharge lamp comprising a xenon gas as a discharge gas sealed inside and an electrode disposed in a pair on the outer surface of the container or in the vicinity thereof in a mutually opposing area of the vessel wall. And
The electrode includes a first electrode (outer main electrode) continuously disposed on a surface including the dent or constricted portion of the outer surface of the container, an area facing the dent or constricted section, and an adjacent area thereof A second electrode (starting electrode) continuously disposed in the vicinity of the outer surface of the container so as to face the first electrode and with the end portion on the center side of the lamp body facing the top of the dent or constriction In the vicinity of the outer surface of the container that does not face the second electrode of the outer surface of the container in which the first electrode is disposed, the second electrode is separated from the second electrode and is opposed to the first electrode. And a third electrode (inner main electrode) arranged continuously,
Metal tantalum is held in the dent or constriction on the inner surface of the container.

  According to the present invention, since the discharge lamp holds metal tantalum in the constricted portion in the glass container constituting the discharge lamp, this serves as a getter for the impure gas, and the high purity of the xenon gas in the glass container Since this metal tantalum serves as an auxiliary electrode for the start pulse, high startability can be stably obtained.

Schematic sectional view of an excimer lamp of an embodiment of the present invention Schematic sectional view of an excimer lamp according to another embodiment of the present invention. Excimer lamp lighting circuit diagram of an embodiment of the present invention Excimer lamp start or restart time distribution map

  The present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view including a central axis of an electric field coupling type high frequency excimer lamp constituting the present invention. Both ends of the outer tube 1a, which is constricted in advance near the end of the quartz tube, and the inner tube 1b having an outer diameter smaller than the inner diameter of the outer tube 1a are joined together to form one closed space as a whole. The discharge glass container, that is, the lamp body 1 is configured. The lamp body 1 has a so-called double tube structure having a hollow portion at the center.

  On the outer surface of the outer tube 1a, a net-like outer main electrode 3 having a gap that does not block the emitted light is continuously disposed. Further, a glass water cooling tube 2 is disposed inside the inner tube 1b so as to penetrate the hollow portion, and a narrow gap is formed between the inner tube 1b and the glass water cooling tube 2. Then, on the outer surface of the glass water-cooled tube 2, a metal starting electrode 5 that covers the outer surface near the end including the position facing the constriction 6 of the outer tube 1a, and a metal that covers almost the entire other outer surface. An inner main electrode 4 made of metal is disposed. At this time, the end portion of the starting electrode 5 and the end portion of the inner main electrode 4 are separated by a predetermined distance.

  Here, the net-like outer main electrode 3 includes the entire outer surface of the recessed portion of the constriction 6 of the outer tube 1a, and is disposed so as to be in sufficient contact with the outer surface of the outer tube 1a. On the other hand, the inner main electrode 4 and the starting electrode 5 are disposed in contact with the inner surface of the inner tube 1b in order to minimize the distance from the outer main electrode 3 via the discharge glass container (lamp body 1). However, it is disposed on the outer surface of the glass water-cooled tube 2 for the sake of convenience as a form that is easy to implement (manually holding and fixing the electrode). In short, in the present invention, the inner main electrode 4 and the starting electrode 5 need only be disposed in the vicinity of the inner surface of the inner tube 1b in the area facing the outer main electrode 3, and are as close as possible to the inner surface of the inner tube 1b. Of course, it may be arranged in contact with the inner surface of the inner tube 1b by any means.

  In addition, in FIG. 1 (and FIG. 2), the fine drawing about the contact of the glass container surface for discharge and each electrode is abbreviate | omitted.

  The lamp body 1 and the electrodes 3, 4, 5 are cooled by circulating cooling water through the glass water-cooled tube 2.

  In FIG. 1, d1 is the distance between the main electrodes formed by the outer surface of the outer tube 1a and the inner surface of the inner tube 1b, and d2 is the concave bottom of the constriction 6 and the inner tube formed on the outer surface of the outer tube 1a. This is the shortest distance between starting electrodes formed by the inner surface of 1b.

  Metal tantalum is disposed in advance on the outer surface of the inner tube 1b near the tip of the constriction 6 formed inside the outer tube 1a using an appropriate means, and then impure gas such as oxygen and hydrogen remaining in the container. Heating and exhausting are performed in the vicinity of a temperature (about 1000 ° C.) that operates as a getter that adsorbs water.

  Examples of the present invention will be described below. As the material of the outer tube 1a, for example, a quartz tube having an outer diameter of 35 mm, an inner diameter of 33 mm, and a length of 1310 mm is used. As the material of the inner tube 1b, for example, a quartz tube having an outer diameter of 18 mm, an inner diameter of 16 mm, and a length of 1310 mm is used. The end faces of the quartz tubes were each fused and joined to produce a quartz glass container (lamp body 1) having a double tube structure.

  The outer main electrode 3 was made of a 1 mm-thick stainless steel linear member having a cylindrical shape, and was arranged on the outer surface of the outer tube 1 a so as to cover the entire length of the lamp body 1 with a length of 1280 mm. The inner main electrode 4 and the starting electrode 5 are both made of a 1 mm-thick stainless steel plate member that is formed in a cylindrical shape and covers the outer surface of the water-cooled tube 2. The length of the lamp body 1 in the longitudinal direction is 1000 mm for the inner main electrode 4 and 300 mm for the starting electrode 5, and the end 51 of the starting electrode 5 (the end on the center side of the lamp 1) faces the apex of the constriction 6. (See FIG. 1). The end 41 of the inner main electrode 4 and the end 51 of the starting electrode 5 were separated by 20 mm. At this time, a gap of about 1 mm was generated between the inner main electrode 4 and the starting electrode 5 and the inner surface of the inner tube 1b.

  The distance between the main electrodes d1 is 8.5 mm, the constriction 6 is processed and formed to have a width of about 8 mm in the longitudinal direction of the lamp body 1, and the constricted portion has a quartz wall thickness of about 1 mm and is formed on the outer surface of the outer tube 1a. The shortest distance d2 between the starting electrodes formed by the concave bottom of the neck 6 and the inner surface of the inner tube 1b was 5 mm.

  In the lamp body 1, metal tantalum 8 was previously disposed before fusion sealing, and heated and exhausted at 1050 ° C. A xenon gas having a pressure of 79.8 kPa was sealed in the discharge space 7 which is an internal space of the lamp body 1.

  As a simple method for disposing the metal tantalum 8 in the constricted portion 6z, for example, the same method for easily holding the inner tube 1b at a position substantially corresponding to the constriction applied to the outer tube 1a. It is possible to realize this by preliminarily constricting, processing metal tantalum 8 there, and winding it in a ring shape as shown in FIG. 2 (the portion where metal tantalum 8 is held in FIG. 2). The detail drawing of is omitted). Here, the constricted portion 6z indicates an annular area of the lamp body 1 including the constricted portion 6 as shown in FIGS. The metal tantalum 8 is disposed in an area corresponding to the constricted portion 6z inside the lamp body 1.

  The discharge lamp thus configured is started with a high frequency voltage having a frequency of about 2 MHz and a pulse peak voltage of 4 kV between the outer main electrode 3 and the inner main electrode 4 in accordance with the lighting circuit configuration shown in FIG. When a high voltage pulse with a pulse peak voltage of 10 kV is simultaneously applied between the electrode 5 and the electrode 5, electric field coupled electrodeless discharge is started.

  This discharge is considered to start through the following process. First, a high voltage pulse applied between the outer main electrode 3 and the starting electrode 5 by the starter 10 causes dielectric breakdown between both electrodes, and free electrons are generated around the convex surface of the constriction 6 in the lamp body 1. (Seek discharge occurs). At the same time, a high-frequency voltage having a frequency of about 2 MHz and a pulse peak voltage of 4 kV is applied between the outer main electrode 3 and the inner main electrode 4 by the high-frequency power source 9. It is not large enough to initiate a moldless electrode discharge (main discharge). However, the generated free electrons gradually diffuse to a region sandwiched between the outer main electrode 3 and the inner main electrode 4, and this electron becomes a seed fire and main discharge is started.

  Here, as shown in FIGS. 1 and 2, the lamp body center side end portion (end portion 51) of the starting electrode 5 is disposed at a position facing the apex of the constriction 6 for the following reason. That is, with respect to the relative positional relationship between the outer main electrode 3, the inner main electrode 4, and the starting electrode 5, the apex of the constriction 6 (in other words, the protruding portion of the outer main electrode 3) close to the outer main electrode 3 is the starting electrode. 5 so that the shortest distance from the end 51 of the starter electrode 5 and the end 41 of the inner main electrode 4 separated from the end 51 of the starting electrode 5 by a predetermined distance is as short as possible. This is to facilitate the transition from the fire discharge to the main discharge. If the distance between the apex of the constriction 6 and the inner main electrode 4 is too large, the transition to the main discharge is difficult to occur.

Next, when the distribution of the start / restart time was examined, a result as shown in FIG. 4 was obtained. The starting time here refers to the time until the primary current value becomes 0.5I ₀ after voltage application when the primary current value of the high-frequency power source 9 at rated lighting is I ₀ .

  From FIG. 4, it can be seen that the start-up time was shortened to ¼ or less as compared with the conventional excimer lamp, and the variation in the time could be reduced. This is because the metal tantalum 8 installed around the constricted portion in the glass container plays a role as a proximity conductor, that is, an auxiliary electrode, and the amount of initial free electrons generated by the high voltage pulse increases, which is the main discharge. This is thought to be due to shortening the transition time. Thus, according to the present invention, it was confirmed that extremely good startability was realized as compared with the prior art.

  Various specific numerical values and forms in the above-described embodiments are merely examples, and it is possible to appropriately select and adopt values and forms different from the above-described embodiments within the scope of the gist of the present invention.

  It can be suitably used for an electric field coupled discharge lamp (so-called excimer lamp) in which an electrode is disposed outside a glass container in which a discharge gas is sealed, and a high frequency voltage is applied to the electrode.

DESCRIPTION OF SYMBOLS 1 Lamp body 1a Outer tube 1b Inner tube 2 Glass water-cooled tube 3 Outer main electrode 4 Inner main electrode 5 Starting electrode 6 Neck 6z Neck part 7 Discharge space 8 Metal tantalum 9 High frequency power supply 10 Starter 41 Inner main electrode end 51 Start Electrode end

Claims (1)

A glass container having a portion in which at least a part of the vessel wall faces each other, and a portion in which a dent or constriction is disposed on a part or the entire circumference of the outer surface (hereinafter referred to as “dent or constricted portion”), and the container A discharge lamp comprising a xenon gas as a discharge gas sealed inside and an electrode disposed in a pair on the outer surface of the container or in the vicinity thereof in a mutually opposing area of the vessel wall. And
The electrode includes a first electrode continuously disposed on a surface including the dent or constricted portion of the outer surface of the container, an area facing the dent or constricted portion, and the vicinity of the outer surface of the container in an adjacent area. A second electrode continuously disposed so as to face the first electrode and with the end portion on the center side of the lamp facing the top of the dent or constriction, and the first electrode disposed In the vicinity of the outer surface of the container that does not face the second electrode of the outer surface of the container, the first electrode is continuously disposed so as to be separated from the second electrode and to face the first electrode. Consisting of three electrodes,
A discharge lamp characterized in that metal tantalum is held in the dent or constriction on the inner surface of the container.

Images