JP2016039115A - Short-arc discharge lamp and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a short-arc discharge lamp preventing a sealing tube and step-joined glass from being damaged and deformed due to light propagating through the sealing tube.SOLUTION: In a short-arc discharge lamp, a sealing tube 4 provided continuously to an arc tube 3 and an electrode core rod 6 supporting an electrode 5 disposed in the arc tube 3 are sealed via step-joined glass 7. In the short-arc discharge lamp, a light radiation surface and a light reflection surface are provided on the surface of the sealing tube 4, and light propagating through the sealing tube 4 is radiated from the light radiation surface to the outside.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a short arc discharge lamp suitable for a light source such as an exposure apparatus and a projection apparatus, and a light source device using the short arc discharge lamp.

  2. Description of the Related Art Conventionally, as a light source for a projection apparatus, a short arc discharge lamp in which a discharge gas mainly composed of a rare gas such as xenon gas is enclosed in an arc tube 3 as shown in FIG.

  In this short arc discharge lamp, a quartz glass sealing tube 4 is continuously formed on both ends of a quartz glass arc tube 3, and a pair of electrodes 5 mainly composed of tungsten or molybdenum is formed in the arc tube 3. The electrode 5 is held by being bonded to an electrode core bar 6 mainly composed of tungsten or molybdenum.

  In addition, this short arc discharge lamp (hereinafter referred to as a lamp) increases the brightness by increasing the discharge gas pressure inside the arc tube during operation. In addition, since mercury is not sealed inside the arc tube, the current value flowing through the lamp when the lamp is lit is higher than that of a short arc mercury discharge lamp in which mercury is sealed. Therefore, in order to supply a large current to the electrode 5 without damaging the sealed tube 4 even at a high sealed gas pressure, the electrode core bar 6 joined to the electrode 5 is protruded from the end of the sealed tube and sealed. A step glass sealing structure in which the electrode core 6 and the sealing tube 4 are sealed via a step glass 7 inside the stop tube 4 is used.

  A base 8 may be provided in the sealing tube 4. Furthermore, the base 8 may be electrically connected to the electrode core 6. The base 8 has functions such as holding a lamp or attaching a wiring for supplying a lighting current to the electrode core 6.

  Xenon gas is sealed as a discharge gas in the arc tube 3 at atmospheric pressure or higher, and when lighting power is supplied to the lamp, an arc is generated by discharge between the electrodes, and ultraviolet light from the arc centered on visible light to infrared light. A wide range of light up to light is emitted. As shown in FIG. 1, the lamp 2 is arranged in an elliptical reflecting mirror 1 which is open at one end and focuses on an arc. The light emitted from the lamp is collected by the reflecting mirror 1 and used.

  However, part of the light emitted from the arc propagates through the arc tube 3 and the sealing tube 4 connected to the arc tube 3 so that the light is totally reflected inside the optical fiber (hereinafter referred to as the optical fiber effect). . Further, the arc has a certain spread, and the light emitted from the arc at a position out of the focus of the reflecting mirror 1 is not properly collected by the reflecting mirror 1, and the arc tube 3 or the sealing tube 4. Will be irradiated. Part of the irradiated light propagates inside the arc tube 3 and the sealing tube 4 by the optical fiber effect.

  FIG. 4 is a cross-sectional view of a conventional step glass sealing structure in which a sealing tube 4 and an electrode core rod 6 are joined via a step glass 7. The sealing tube 4 is joined to the step glass 7 via a protruding portion 9 that draws an arc outside the lamp axis. In general, since the shape of such a sealing tube is processed and deformed by melting or the like, a minute processing distortion remains in the protruding portion 9 of the sealing tube 4 at the time of manufacturing.

  A part L1 of the light emitted from the arc propagates inside the sealing tube 4 toward the end in the lamp axial direction and concentrates on the protruding portion 9 of the sealing tube 4. The light generated by the discharge is light in a wide range from ultraviolet rays to infrared rays, and the ultraviolet rays break the molecular bonds of the quartz glass constituting the sealing tube 4 and degrade the quartz glass. In particular, when ultraviolet rays concentrate on a strained portion such as the protruding portion 9 of the sealing tube 4, the molecular bond in the strained portion is cut and the quartz glass becomes brittle, and cracks are eventually generated. If the lamp is lit in a cracked state, the lamp may burst starting from the crack by the high-pressure discharge gas.

  Similarly, infrared rays concentrate on the protruding portion 9 of the sealing tube 4 and the protruding portion 9 of the sealing tube is heated. As a result, the protrusion 9 is further distorted by heat, and cracks due to the concentration of ultraviolet rays are likely to occur. In addition, when the sealing tube including the protruding portion 9 is heated, the step glass 7 holding the electrode core bar 6 is also heated. When the temperature of the step glass 7 exceeds the strain point, distortion occurs in the step glass 7, and the temperature of the step glass 7 exceeds the strain point for a long time. To do. Further, when the temperature of the step glass 7 exceeds the softening point, the step glass 7 is greatly deformed in a short time. The step glass 7 is deformed to the outside in the lamp axis direction by the discharge gas in a high pressure state during lighting, and the position of the electrode supported by the electrode core rod is also moved along with the step glass. For this reason, the position of the arc deviates from the focal point of the reflecting mirror, and the utilization efficiency of the emitted light decreases. In addition, there is a case where the lamp cannot be normally lit due to a change in the characteristic of the lighting power of the lamp due to the variation in the distance between the electrodes.

  On the other hand, by providing a light reflecting member on the outer surface of the sealing tube 4, it is possible to prevent the sealing tube 4 from being irradiated with light. However, the sealing tube 4 is heated to several hundred degrees during lamp operation. As a result, for example, stress is applied to the sealing tube 4 due to a difference in thermal expansion between the sealing tube 4 and the light reflecting member, so that the sealing tube 4 is damaged, or components of the light reflecting member react with the sealing tube 4. However, the strength of the sealing tube 4 may be deteriorated, which may cause a problem such as the sealing tube 4 being damaged. In addition, the light reflecting member cannot prevent light propagating inside the sealing tube. Furthermore, if a light reflecting member that can withstand such a temperature environment of several hundred degrees is provided on the surface of the sealing tube, the lamp manufacturing cost increases.

  In order to solve the above-mentioned problem, a short arc discharge lamp according to claim 1 includes an arc tube having a pair of electrodes therein, an electrode core that supports the electrode, and an arc tube connected to the arc tube. A sealing tube that seals against the electrode rod, the sealing tube being connected to the outer sealing tube and the outer sealing tube, and having an outer diameter of the lamp shaft. An outer sealing tube diameter-reducing portion that is reduced in diameter toward the outer side, and the outer sealing tube diameter-reducing portion that is continuously provided along the lamp radial direction on the electrode core rod side of the outer sealing tube diameter-reducing portion. An outer sealing tube end, an inner sealing tube connected to the arc tube side of the outer sealing tube end, and a step glass that is connected to the inner sealing tube and sealed to the electrode rod; A short arc discharge lamp comprising: an outer end surface of the outer sealing tube at an end surface in a lamp axial direction; A first flat surface along the radial direction of the lamp on the side, and a portion of the inner peripheral surface on the electrode core bar side of the outer sealing tube end is on the outer side in the lamp axial direction of the outer sealing tube end It has a diameter-expanding part that expands inward in the lamp axial direction and has an inner diameter larger than the inner diameter of the end face.

  The short arc discharge lamp according to claim 2 is the short arc discharge lamp according to claim 1, wherein the first flat surface transmits light propagating through the outer sealing tube. A first light-emitting surface that radiates to the outside, wherein the enlarged-diameter portion is a light-reflecting surface that reflects light propagating inward in the radial direction of the lamp through the inside of the outer sealing tube end in the lamp axis direction. It is characterized by being.

  The short arc discharge lamp according to claim 3 is the short arc discharge lamp according to claim 2, wherein the outer end of the outer sealing tube has an inner peripheral surface and an inner peripheral surface on the lamp end side. A tubular light guiding portion having a continuous surface, and a second flat surface along a radial direction of the lamp at a lamp axial direction outer end surface of the tubular light guiding portion, wherein the second flat surface is The second light emitting surface is characterized in that it is a second light emitting surface that emits the light reflected by the light reflecting surface and propagating through the light guiding portion to the outside.

  The short arc discharge lamp according to claim 4 is the short arc discharge lamp according to claim 2 or 3, wherein a portion having the maximum inner diameter of the enlarged diameter portion is an end portion of the outer sealed tube. It is characterized in that it is on the arc tube side from the center in the lamp axial direction.

  A light source device according to claim 5 is a light source device including the short arc discharge lamp according to claim 1, and is disposed so as to surround the short arc discharge lamp and the short arc discharge lamp. The sealing tube having a flat surface on the outer end surface in the lamp axis direction of the end portion of the outer sealing tube on the opening side of the reflecting mirror. Is provided with a short arc discharge lamp.

  According to the present invention, the light propagating through the inside of the sealing tube is prevented from concentrating on the end of the sealing tube, and the light propagating through the inside of the sealing tube by the optical fiber effect is emitted outward in the lamp axis direction. It is possible to prevent the lamp from being damaged or the electrode from being displaced due to ultraviolet rays and infrared rays contained in the light.

Schematic sectional view of the lamp and reflector of the present invention Schematic sectional view of the lamp of the present invention Cross-sectional view of a sealing structure according to an embodiment of the present invention Cross-sectional illustration of a conventional lamp sealing structure Cross-sectional explanatory drawing of the sealing structure of a lamp having a flat surface at the end of the outer sealing tube Cross-sectional explanatory drawing of a sealing structure of a lamp having a reduced diameter portion of the outer sealing tube Cross-sectional explanatory drawing of a sealing structure having an enlarged diameter portion according to an embodiment of the present invention Cross-sectional explanatory diagram of a sealing structure having a light guiding portion according to an embodiment of the present invention

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a schematic sectional view showing the structure of the lamp of the present invention.

  This lamp has an arc tube 3 having a pair of electrodes 5 inside, an electrode core 6 that is joined to the electrode 5 and supports the electrode 5, and is connected to both ends of the arc tube 3. And a sealing tube 4 for sealing the electrode core 6. A base 8 may be provided at the end of the sealing tube. The arc tube 3 is a short arc discharge lamp in which xenon gas is enclosed as a discharge gas at atmospheric pressure or higher.

  The sealing structure of the lamp of the present invention will be described with reference to FIG. 3 showing a sectional view of the sealing structure of the embodiment of the present invention.

  The sealing tube 4 is provided continuously with the outer sealing tube 401 connected to the arc tube 3, and the outer sealing tube reduced diameter portion 402 is provided continuously with the outer sealing tube 401 and the outer diameter thereof is reduced toward the outside in the lamp axis direction. The outer sealing tube diameter-reduced portion 402, the outer sealing tube diameter-reduced portion 402 on the electrode core rod side of the outer sealing tube end portion 403 along the lamp radial direction, and one end of the outer sealing tube diameter-reduced portion 402 The inner sealing tube 404 is connected to the arc tube side of the end 403 and connected to the step glass 7 at the other end.

  On the outer end surface in the lamp axial direction of the outer sealing tube end 403, a lamp is used as a light emitting surface for radiating light propagating through the inside of the outer sealing tube, which will be described later, inside the inner diameter of the outer sealing tube. It has a flat surface (first light emitting surface) 405 along the radial direction. A part of the inner peripheral surface 406 on the electrode core rod side of the outer sealing tube end 403 reflects light propagating inward in the radial direction of the lamp in the outer side of the outer sealing tube 403, which will be described later, in the lamp axial direction. As the light reflecting surface, there is an enlarged diameter portion 407 that has an inner diameter R2 that is larger than an inner diameter R1 of the outer end surface in the lamp axis direction of the outer sealing tube end portion 403. The portion having the maximum inner diameter is provided on the arc tube side from the center M1 of the outer sealing tube end 403 in the lamp axis direction. The lamp axis direction center M1 is the middle thickness in the lamp axis direction of the thinnest portion of the outer sealing tube end 403 having the first light emission surface 405.

  On the outer side in the lamp axial direction of the outer sealing tube end 403, there is a tubular light guiding portion 408 in which the inner surface of the electrode core rod side and the inner surface are continuous, and the outer side of the tubular light guiding portion 408 in the lamp axial direction. A flat surface (second surface) along the lamp radial direction is formed on the end surface as a light emitting surface that is reflected by a diameter-enlarged portion 407 that is a light reflecting surface to be described later and radiates light propagating through the light guiding portion 408 to the outside. Light emitting surface) 409.

  1 and 2, when lighting power is supplied to the lamp, an arc is generated by the discharge between the electrodes 5, and light in a wide range from ultraviolet light to infrared light centering on visible light is emitted from the arc. . The emitted light is emitted from the arc tube 3 to the outside, and is collected by the reflecting mirror 1 provided so as to focus the arc around the lamp. However, part of the light emitted from the arc propagates inside the arc tube 3 and the sealing tube 4 due to the optical fiber effect. At the same time, part of the light emitted from the arc at a position off the focal point of the reflecting mirror 1 is applied to the arc tube 3 and the sealing tube 4 by the reflecting mirror, and the arc tube 3 and the sealing tube 4 are irradiated by the optical fiber effect. Propagate inside.

  FIG. 5 shows a cross-sectional explanatory view of a sealing structure of a lamp having a flat surface at the end of the outer sealing tube. As shown in FIG. 5, all the outer end surfaces in the lamp axis direction of the outer sealing tube end portion 403 are flat surfaces (first light emitting surfaces) 405, so that all of the light L1 propagating in the outer sealing tube 401 is obtained. The reflection can be suppressed and the light L1 can be emitted to the outside. However, a portion 10 where the thickness of the sealing tube becomes extremely thick is formed at the outer sealing tube end portion 403, and thermal distortion occurs in this portion due to a difference in heating and cooling conditions when the lamp is turned on and off. As a result, before the light L1 propagating in the outer sealing tube 401 is radiated from the first light emitting surface 405, it propagates to the portion 10 where the thermal strain is generated and is caused by the ultraviolet rays contained in the light L1. It breaks molecular bonds of thermal strain. As a result, there was a risk that a crack occurred in the portion 10 where the thermal strain occurred, and the lamp was eventually damaged.

  Therefore, as shown in FIG. 6, the outer sealing tube 401 and the outer sealing tube have an outer sealing tube reduced diameter portion 402 that reduces the outer diameter of the outer sealing tube 401 to be equal to or smaller than the inner diameter of the outer sealing tube 401. A first light emitting surface 405 is provided between the end portions 403 and on the inner side in the lamp radial direction from the inner diameter of the outer sealing tube 401. Thereby, generation | occurrence | production of the thermal distortion by the extreme thickness increase of the outer side sealing tube edge part 403 is suppressed, and the light L1 which propagates the inside of the outer side sealing tube 401 can be radiated | emitted outside.

  However, the outer surface of the outer sealing tube diameter-reduced portion 402 is a curved surface, so that a part of the light L2 propagating through the outer sealing tube 401 is not emitted from the first light emitting surface 405 to the outside. Then, it propagates inside the outer sealing tube end 403 toward the inside in the radial direction of the lamp, radiates from the electrode core rod side inner peripheral surface 406 of the outer sealing tube end 403, and irradiates the electrode core 6. Thereby, the portion 601 irradiated with the infrared rays of the electrode core 6 is heated by the infrared rays contained in the light L2, and the temperature rises.

  In the step glass sealing structure for sealing the electrode core 6 and the step glass 7 used in the short arc discharge lamp of the present invention, a metal foil is welded to the electrode core and the metal foil is sealed with a sealing tube. Compared with the metal foil sealing structure, the sealing structure is weak against the temperature of the electrode core bar. This is because the stepped glass has a lower strain point and softening point and lower heat resistance than a quartz tube used as a sealing tube.

  The step glass 7 is heated when the electrodes are heated by lighting and the heat is transmitted from the electrodes through the electrode core rod. When the temperature of the portion 601 irradiated with infrared rays of the electrode core 6 rises, not only from the electrode but also from the portion 601 side irradiated with infrared rays, the step glass 7 is further heated, resulting in a higher temperature. become.

  The arc tube 3 is filled with xenon as a discharge gas at atmospheric pressure or higher, and the step glass 7 in contact with the discharge gas always faces from the inside to the outside of the arc tube regardless of whether the lamp is on or off. Under pressure. Therefore, when the heat is transmitted also from the portion 601 irradiated with infrared rays, the step glass 7 is further heated, and when the temperature exceeds the strain point and further the softening point, the step glass 7 swells outside the arc tube. The electrode core bar 6 held by the step glass 7 and the position of the electrode 5 supported by the electrode core bar 6 are moved. As a result, problems such as a change in lamp lighting power characteristics due to an increase in the distance between the electrodes and a decrease in illuminance due to an arc generated in the electrodes deviating from the focus of the reflecting mirror 1 occur. Further, when the arc deviates from the focal point of the reflecting mirror 1, the amount of light applied to the sealing tube 4 by the reflecting mirror 1 increases, and the above-mentioned problem may become more serious.

FIG. 7 is an explanatory cross-sectional view of a sealing structure having an enlarged diameter portion according to an embodiment of the present invention.
As shown in FIG. 7, a part of the inner surface 406 on the electrode core rod side of the outer sealing tube end 403 has an outer surface as a reflecting surface that reflects light L <b> 2 propagating inward in the lamp radial direction in the lamp axial direction. A diameter-enlarged portion 407 that has an inner diameter R2 that is larger than an inner diameter R1 of the lamp axial direction outer end face of the end portion of the sealing tube is provided on the inner side in the lamp axial direction. Thereby, it can suppress that the light L2 is radiated | emitted from the electrode core-rod side internal peripheral surface 406 toward the electrode core rod 6, and can prevent the electrode core rod 601 from being heated.

  However, by providing the enlarged diameter portion 407 which is a light reflecting surface, a part of the light L2 is reflected to the inside in the lamp axis direction, that is, the arc tube side, and a part of the reflected light L2 is inside the inner sealing tube 404. To propagate. Thereby, the light L2 propagates to the step glass 7 and raises the temperature of the step glass 7, or the light L2 is radiated from the inner sealing tube 404 to the electrode core 6 and raises the temperature of the electrode core 6. As a result, there is a possibility that a problem may occur due to the temperature of the above-mentioned step glass 7 exceeding the strain point and further the softening point.

  Therefore, the diameter-expanded portion 407 has the largest diameter, that is, the largest inner diameter is provided on the arc tube side from the center M1 of the outer sealing tube end 403 in the lamp axis direction. Thereby, most of the light L2 propagating through the outer sealing tube end 403 toward the inner side in the lamp radial direction can be reflected outward in the lamp axial direction, and the temperature rise of the step glass 7 can be suppressed. . As described above, in order to reflect the light outward in the lamp axis direction without radiating the light L2 to the electrode core bar 601 side, the sectional shape of the electrode core bar side inner peripheral surface 406 having the enlarged diameter portion 407 in the lamp axis direction. Is preferably substantially V-shaped.

FIG. 8 is a cross-sectional explanatory view of a sealing structure having a light guiding portion according to an embodiment of the present invention.
As shown in FIG. 8, a tubular light guiding portion 408 having an inner surface continuous with the electrode core rod inner peripheral surface 406 is provided on the outer end surface in the lamp axial direction of the outer sealing tube end portion 403, and the lamp of the light guiding portion 408 is provided. A flat surface 409 (second light emitting surface) is provided on the axially outer end surface. The light L2 propagating through the outer sealing tube end 403 toward the inner side in the lamp radial direction is reflected toward the outer side in the lamp axis direction by the enlarged diameter portion 407 that is a light reflecting surface, and propagates through the light guiding portion 408. The light L2 that has propagated through the light guiding portion 408 is emitted from the second light emitting surface 409 to the outside.

  Without the light guiding portion 408, the light emitted from the first light emitting surface 405 may be irradiated near the electrode core bar 601. However, the light L2 propagates in the light guiding portion 408 and is emitted from the second light emitting surface 409 away from the outer sealing tube end 403, so that the light emitted to the outside is near the electrode core rod 601. Irradiation can be prevented, and light emitted to the electrode core 6 can be prevented from being irradiated, or the electrode core can be irradiated more outward in the lamp axis direction. Thereby, the temperature rise of the step glass 7 resulting from the light radiated | emitted from the sealing tube 4 can be suppressed.

  In addition, in order to suppress the light L1 propagating through the outer sealing tube end 401 from being irradiated from the arc tube side end surface 410 of the outer sealing tube end 403 to the inner sealing tube 404 or the step glass 7. The arc tube side end surface 410 is preferably a curved surface. However, if it is necessary to provide a flat surface along the lamp radial direction on the arc tube side end surface 410 in order to suppress the thickness difference of the outer sealing tube end portion 403, the area of the flat surface is at least It is desirable that it is smaller than the first light emitting surface 405.

  As shown in FIG. 1, one of the lamps is open, and is arranged inside an elliptical reflecting mirror 1 having an arc as a focal point. Therefore, the sealing tube on the opening side of the reflecting mirror is sealed as compared with the other sealing tube by irradiating the reflecting mirror 1 with light emitted from the arc at a position off the focal point of the reflecting mirror. The incidence of problems such as breakage of the sealing tube due to light propagating inside the tube and deformation of the step glass is increased. Therefore, it is desirable that the above-described sealing tube having a structure that radiates light propagating through the sealing tube described above is used at least for the sealing tube on the opening side of the reflecting mirror.

1: Reflector 2: Lamp 3: Arc tube 4: Sealing tube 401: Outer sealing tube 402: Outer sealing tube reduced diameter portion 403: Outer sealing tube end 404: Inner sealing tube 405: Flat surface ( First light emitting surface)
406: Electrode core side inner peripheral surface 407: Expanded diameter portion 408: Tubular light guiding portion 409: Flat surface (second light emitting surface)
5: Electrode 6: Electrode core rod 7: Step glass 8: Base 9: Protruding portion 10 of the sealing tube 10: Thermal strained portion M1: Lamp axial direction center R1 of the outer sealing tube end R1: Lamp axial direction Inner diameter R2 of the outer end surface: Maximum inner diameter of the expanded portion

Claims (5)

An arc tube with a pair of electrodes inside;
An electrode core rod supporting the electrode;
It consists of a sealing tube that is connected to the arc tube and is sealed to the electrode rod,
The sealing tube is
An outer sealing tube connected to the arc tube;
An outer sealing tube diameter-reduced portion connected to the outer sealing tube and having an outer diameter reduced toward the outside in the lamp axis direction;
Continuing to the outer sealing tube diameter reducing portion,
An outer sealing tube end along the lamp radial direction on the electrode core rod side of the outer sealing tube diameter-reduced portion; and
An inner sealing tube connected to the arc tube side of the outer sealing tube end; and
In a short arc discharge lamp comprising a step glass that is connected to the inner sealing tube and sealed with the electrode rod,
On the outer end surface of the outer sealing tube end in the lamp axial direction,
A first flat surface along the lamp radial direction inside the lamp radial direction from the inner diameter of the outer sealing tube,
In a part of the electrode core bar side inner peripheral surface of the outer sealing tube end,
A short arc discharge lamp having a diameter-expanding portion having an inner diameter larger than an inner diameter of an outer end surface in the lamp axial direction of the outer sealing tube end portion and expanding inward in the lamp axial direction. The first flat surface is
A first light emitting surface for radiating light propagating inside the outer sealing tube to the outside of the sealing tube;
2. The short according to claim 1, wherein the enlarged-diameter portion is a light reflecting surface that reflects light propagating inward in the lamp radial direction inside the outer sealing tube end in the lamp axial direction. Arc discharge lamp. On the outer side of the outer sealing tube end in the lamp axial direction,
The electrode core rod side inner peripheral surface and the inner surface has a tubular light guide portion that is continuous,
On the outer end surface in the lamp axis direction of the tubular light guiding portion,
A second flat surface along the lamp radial direction;
The second flat surface is
3. The short arc discharge lamp according to claim 2, wherein the short arc discharge lamp is a second light emitting surface that radiates light that is reflected by the light reflecting surface and propagates inside the light guiding portion. The portion having the maximum inner diameter of the expanded portion is
The short arc discharge lamp according to any one of claims 2 to 3, wherein the short arc discharge lamp is located closer to the arc tube than the center of the outer sealing tube end in the lamp axial direction. The short arc discharge lamp;
Arranged to surround the short arc discharge lamp,
It consists of an elliptical mirror with one open,
On the opening side of the reflector,
5. A light source device comprising the short arc discharge lamp according to claim 1, wherein the sealing tube having a flat surface is provided on an outer end surface in the lamp axial direction of the end portion of the outer sealing tube.

Images