JP2017069077A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform highly accurate light radiation with uniform light intensity of less unevenness.SOLUTION: In a radiation lamp including a negative electrode 3 and a positive electrode 4 placed in a radiation container 2 at a predetermined interval while facing the tips, a reflection suppression groove 31 for suppressing reflection of the light, generated by arc discharge between the negative electrode and positive electrode, is provided in the outer peripheral surface 22a of the positive electrode diameter reduction part 22 of the positive electrode placed in discharge container, thus suppressing generation of reflection light radiated to the outside of the discharge container and becoming a stray light component.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a discharge lamp that emits light of a specific wavelength, such as a short arc discharge lamp.

  Conventionally, a short arc type discharge lamp has been used as a discharge lamp that emits light by arc discharge. A short arc type discharge lamp is to hold a anode and cathode close to each other in a discharge vessel filled with rare gas, mercury, metal halide, etc., and apply a voltage between the anode and cathode. An arc discharge is generated by radiating light of a specific wavelength such as ultraviolet light.

  Since this type of short arc type discharge lamp has a short distance between the electrodes, it can be regarded as a point light source and light with high radiance can be obtained. Therefore, the short arc type discharge lamp is widely used as a light source of an exposure apparatus that exposes a fine exposure pattern such as a wiring circuit pattern formed on a semiconductor device or a printed wiring board.

  In a short arc type discharge lamp used as a light source of this type of exposure apparatus, it is desirable that light generated by arc discharge is taken out of the discharge vessel with high efficiency and used effectively for exposure pattern exposure.

  As a discharge lamp in which light generated by arc discharge is taken out of the discharge vessel with high efficiency, a discharge lamp as described in Japanese Patent Application Laid-Open No. 2009-238664 (Patent Document 1) has been proposed. The discharge lamp disclosed in Patent Document 1 increases the illuminance of radiated light radiated to the outside of the discharge vessel by reflecting light generated by discharge at a part of the electrode.

JP 2009-238664 A

  By the way, in order to expose the fine exposure pattern formed on the exposure mask with high accuracy in the exposure apparatus, it is possible to uniformly expose the entire surface of the exposure pattern using high-precision light with no unevenness in light intensity. Required.

  Therefore, the technical problem of the present invention is proposed for the purpose of providing a discharge lamp that can emit high-precision light with less unevenness in light intensity and uniform light intensity.

  The present invention proposed to achieve the above-mentioned object is a discharge lamp comprising a cathode and an anode disposed in a discharge vessel with their front ends facing each other at a predetermined interval, A reflection suppressing means for suppressing reflection of light generated by arc discharge generated between the cathode and the anode is provided on the anode arranged in the above.

  The reflection suppressing means used in the present invention is preferably provided in the direction of arc discharge generated between the cathode and the anode.

  The anode used in the present invention has a cylindrical body portion and a distal end surface, and the outer diameter is gradually increased from the base end side continuous to the body portion toward the distal end portion where the distal end surface is formed. The cathode has a cylindrical body, and a cathode whose diameter is gradually reduced from the base end side continuous to the body part toward the distal end. A reflection suppressing means that has a diameter portion and suppresses reflection of light generated by arc discharge generated between the cathode and the anode is provided in the reduced diameter portion of the anode.

  The reflection suppressing means constituting the present invention includes a light reflecting means that repeats reflection of incident light generated by an arc discharge generated between the cathode and the anode, and is reflected outside the reflection suppressing means. It consists of the groove part which suppresses.

  Further, the reflection suppressing means constituting the present invention is formed as a groove portion that gradually decreases in width from the opening side to which the light generated by the arc discharge generated between the cathode and the anode enters and toward the bottom side. It is characterized by. The groove constituting the reflection suppressing means is formed such that the opening angle on the opening side is larger than the opening angle on the bottom side.

  The light whose reflection is suppressed by the reflection suppressing means constituting the present invention includes the light reflected directly from other portions in addition to the light directly input from the arc discharge.

  Note that the reflection suppressing means constituting the present invention has at least a configuration that suppresses radiation to the outside by repetitive reflection of incident light generated by arc discharge. Modifications can be made as appropriate without departing from the scope of the invention.

  Since the discharge lamp according to the present invention can suppress the reflection of light between the anode and the cathode by the reflection suppressing means provided in the anode disposed in the discharge vessel, the stray light caused by this reflection The component can be suppressed and highly accurate light having uniform light intensity can be emitted.

  The discharge lamp according to the present invention makes it possible to expose a fine exposure pattern formed on the exposure mask with high accuracy by emitting high-precision light having uniform light intensity.

  The advantages obtained by the present invention will become more apparent from the embodiments for carrying out the present invention described below.

It is a side view which shows typically the short arc type discharge lamp to which this invention is applied. It is a side view which shows the arrangement | positioning relationship of the cathode and anode which comprise this invention. It is a fragmentary perspective view of the anode which shows typically the anode diameter reduction part in which the groove part for reflection suppression was formed. It is a fragmentary sectional view of the anode which shows typically the groove part for reflection control formed in the anode diameter reduction part. It is a sectional side view which shows typically the arrangement | positioning relationship between a cathode and an anode. The reflective state of light L ₁ incident on the groove for antireflection is a partial cross-sectional view schematically showing. It is a fragmentary sectional view of the anode which shows typically other examples of a groove part for reflection control formed in an anode diameter reduction part. It is a sectional side view which shows the further another example of the groove part for reflection suppression provided in an anode diameter reducing part.

  Embodiments in which the present invention is applied to a short arc type discharge lamp will be described below with reference to the drawings.

  The present embodiment is a short arc type discharge lamp 1, which is used, for example, as a light source of an exposure apparatus used to expose and form a circuit pattern of a semiconductor device. As shown in FIG. 1, a discharge vessel 2 formed of quartz glass having excellent heat resistance and light transmittance, and a cathode 3 and an anode 4 disposed in the discharge vessel 2 are provided.

At opposite positions of the discharge vessel 2, first and second sealing tubes 5 and 6 made of quartz glass are formed integrally with the discharge vessel 2 so as to protrude outward of the discharge vessel 2. ing. As shown in FIG. 1, the first and second sealing tubes 5 and 6 are formed in a cylindrical shape having an outer peripheral diameter smaller than the outer diameter of the discharge vessel 2 with the central axes P ₀ aligned with each other. Yes. At the ends of the first and second sealing tubes 5 and 6, the discharge lamp 1 according to the present embodiment is electrically connected to an external device such as an exposure device and mechanically supported. The bases 7 and 8 are attached.

The first sealing tube 5 is inserted and supported by a cathode support shaft 9 having a tip 3 attached to the cathode 3, and the second sealing tube 6 is supported by an anode support shaft having an anode 4 attached to the tip. 10 is inserted and supported. The cathode support shaft 9 and the anode support shaft 10 are supported with their central axes aligned with the central axes P ₀ of the first and second sealing tubes 5 and 6, respectively.

As shown in FIG. 2, the cathode 3 is attached with the electrode axis P ₁ , which is the central axis of the cathode 3, aligned with the central axis of the cathode support shaft 9. Similarly, as shown in FIG. 2, the anode 4 is attached so that the electrode axis P < _b > ₂ that is the central axis of the anode 4 coincides with the central axis of the anode support shaft 10. Therefore, as shown in FIG. 1, the cathode 3 and the anode 4 are positioned and disposed in the discharge vessel 2 with their tip portions facing each other at a predetermined interval in a state where the electrode axes P ₁ and P ₂ are aligned and coaxial. Is done.

  The cathode support shaft 9 and the anode support shaft 10 that respectively support the cathode 3 and the anode 4 are interposed through conductive metal foils 11 and 12 disposed in the first and second sealing tubes 5 and 6. The lead shafts 13 and 14 disposed on the caps 7 and 8 are electrically connected.

  Although not shown, the first and second sealing tubes 5 and 6 are sealed by being melted and welded to a sealing glass material housed in the sealing tubes 5 and 6. Then, the discharge space DS configured in the discharge vessel 2 is sealed. The sealed discharge space DS in the discharge vessel 2 is filled with rare gas such as mercury, xenon, or argon.

  The short arc type discharge lamp 1 includes a lead shaft 13 and 14, metal foils 11 and 12, a cathode support shaft 9, and an anode support shaft 10, between the electrically insulated cathode 3 and anode 4. When a high voltage is applied, an arc discharge is generated between the cathode 3 and the anode 4. The cathode 3 and the anode 4 are heated by the Joule heat generated by the arc discharge and the heat generated by the arc discharge.

  The cathode 3 used in the discharge lamp 1 according to the present embodiment is formed using tungsten, which is a refractory metal material, or an alloy containing tungsten as a main component. As shown in FIG. 2, the cathode 3 made of a tungsten sintered body is formed with a cathode body portion 15 on the base end portion side which is an attachment portion side to the cathode support shaft 9, and an electron emission portion on the tip end side. A cathode reduced diameter portion 16 is formed on the side.

The cathode body portion 15 is formed in a columnar shape having a constant outer peripheral diameter from the base end side to the tip end side. A support shaft fitting hole 17 is formed on the base end side of the cathode body 15. The support shaft fitting hole 17 is bored from the base end side of the cathode body portion 15 to the middle portion of the tip end portion side with the central axis coinciding with the electrode axis P ₁ of the cathode 3. The cathode 3 is electrically connected to the cathode support shaft 9 and mechanically fixed and supported by fitting the support shaft fitting hole 17 to the tip of the cathode support shaft 9. Cathode 3, because it is the support shaft fitting hole 17 which is formed to match the central axis electrode axis P ₁ attached fitted to the cathode support shaft 9, as shown in FIG. 1, a cathode electrode axis P ₁ It is arranged in the discharge vessel 2 so as to coincide with the central axis of the support shaft 9 and the central axis P ₀ of the first sealing tube 5.

The cathode diameter-reduced portion 16 is formed so as to form a substantially conical shape that gradually decreases in diameter from the base end side serving as a continuous portion to the cathode body 15 toward the tip end side serving as an electron emission portion. ing. The tip end side of the cathode reduced diameter portion 16 is formed so as to be sharpened in order to achieve concentrated and stable electron emission. In the present embodiment, the tip of the cathode diameter-reduced portion 16 has a certain area so as to cut out a part of the sharp tip in order to prevent consumption due to excessive temperature rise due to the concentration of arc discharge. A circular front end surface 18 having the shape is formed. The distal end surface 18 is formed in a concentric circular centered on the electrode axis P _1.

  On the other hand, the anode 4 is formed of tungsten, which is a refractory metal material, or an alloy containing tungsten as a main component. As shown in FIG. 2, the anode 4 made of a tungsten sintered body has an anode body portion 21 which is a mounting portion side to the anode support shaft 10 on the base end side and a cathode contraction diameter of the cathode 3 on the tip end side. An anode diameter-reduced portion 22 facing the portion 16 is provided.

  The anode body portion 21 is formed in a columnar shape having a constant outer diameter from the base end side to the tip end side.

The anode diameter-reduced portion 22 is formed so as to form a conical shape whose diameter is gradually reduced from the base end side continuous to the body portion 21 toward the tip end side. A circular tip surface 23 is formed at the tip of the anode reduced diameter portion 22. The distal end surface 23 is formed in a concentric circular in which the electrode axis P ₂ at the center. Further, the tip surface 23 of the anode 4 constitutes a discharge surface that generates an arc discharge with the tip surface 18 serving as a discharge surface on the cathode 3 side.

A support shaft fitting hole 24 is formed on the base end side of the anode body 21. The support shaft fitting hole 24 is formed from the base end side of the anode body portion 21 to the middle portion of the tip end portion side so that the central axis coincides with the electrode axis P ₂ of the anode 4. The anode 4 is electrically connected to the anode support shaft 10 and mechanically fixed and supported by fitting the tip end portion of the anode support shaft 10 through the support shaft fitting hole 24. At this time, the anode 4, since it is the support shaft fitting hole 24 which is formed to match the central axis electrode axis P ₂ mounting fitted to the anode support shaft 10, as shown in FIG. 1, the electrode axis P ₂ is arranged in the discharge vessel 2 so as to coincide with the central axis of the anode support shaft 10 and the central axis P ₀ of the second sealing tube 6.

As described above, the cathode 3 and the anode 4 are attached to the first and second sealing tubes 5 and 6 formed in the discharge vessel 2 with the center axes P ₀ aligned with each other, with the center axes aligned with each other. by being supported respectively to match the electrode axis P _1, P ₂ to the central axis of the cathode support shaft 9 and the anode support shaft 10, is arranged in the discharge vessel 2 is coincident electrode axis P _1, P ₂ from each other (See FIG. 1).

  When the cathode support shaft 9 and the anode support shaft 10 are fixedly supported by the first and second sealing tubes 5 and 6, the cathode 3 and the anode 4 are connected to the tip surface 18 of the cathode 3 and the tip surface of the anode 4. The inter-electrode distance D formed between the first and second electrodes 23 is positioned so as to maintain a constant distance.

  The anode 4 used in the short arc type discharge lamp 1 is heated during operation and heated to a temperature higher than the cathode 3. Therefore, as shown in FIG. 2, the anode 4 is formed sufficiently larger than the cathode 3 in order to increase the heat capacity and suppress excessive temperature rise. The anode 4 that is larger than the cathode 3 can increase the radiant heat from the outer surface while increasing the heat capacity by increasing the surface area as well as the volume, and can suppress excessive heating. It becomes.

By the way, in order to realize a stable arc discharge, the short arc type discharge lamp 1 has a cathode 3 and an anode 4 in which the electrode axes P ₁ and P ₂ coincide with each other between very short electrodes of about 1 to 15 mm. Oppositely arranged at a distance D. In the discharge lamp 1 having a short interelectrode distance D as described above, one point of the tip surface 18 of the cathode 3 serving as an electron emitting portion is regarded as a bright spot H as shown in FIG. It can be considered that light is emitted.

Therefore, when the cylindrical anode 4 having at least the outer peripheral diameter W ₁ larger than the inter-electrode distance D is arranged coaxially with the cathode 3 and close to the tip surface 18 of the cathode 3, the bright spot H has a large area. It will be covered with the front end surface of the anode 4 which has it. Most of the light emitted with the bright spot H at the tip of the cathode 3 as the emission center is blocked by the tip surface of the anode 4 and scattered in the discharge vessel 2 without going to the outside of the discharge vessel 2. The amount of radiated light is reduced.

Therefore, in the present embodiment, as shown in FIG. 2, the anode diameter-reduced portion 22 that is gradually reduced in diameter from the base end side continuous to the body portion 21 toward the tip end side is provided on one end portion side of the anode 4. Forming. The outer peripheral surface 22 a of the anode reduced diameter portion 22 formed in this way is formed as an inclined surface having a certain inclination angle with respect to the electrode axis P ₂ of the anode 4. By forming such an anode diameter-reduced portion 22, the radiation range R _{1 of} light directly emitted toward the outside of the discharge vessel 2 is expanded without being largely blocked by the tip portion of the anode 4.

That is, the light emission range R ₁ emitted directly toward the outside of the discharge vessel 2 out of the light components emitted around the bright spot H of the tip surface 18 of the cathode 3 is as shown in FIG. A region surrounded by the direction along the outer peripheral surface 16a of the reduced diameter cathode portion 16 with the bright spot H as the center and the direction toward the boundary with the anode body portion 21 on the proximal end side of the reduced anode diameter portion 22 It becomes.

  By the way, in the discharge lamp 1 according to the present embodiment, light by arc discharge is radiated in all directions around the bright spot H of the front end face 18 of the cathode 3. Therefore, a reflection component that is incident on the outer peripheral surface 22a of the anode reduced diameter portion 22 and is reflected by the outer peripheral surface 22a is generated.

The reflected light in the reflected radiation range R ₀ that is reflected and emitted by the outer peripheral surface 22 a of the anode diameter-reduced portion 22 has a radiation direction different from that of the light L ₁ that is directly emitted toward the outside of the discharge vessel 2. When the reflected light whose radiation direction has been changed in the discharge vessel 2 in this way is incident on an optical element such as a lens for focusing the light emitted from the discharge lamp 1 or a mirror for changing the optical path, these optical elements. This causes reflection and diffraction at the edges of the light and generates stray light components. Inclusion of stray light components in the light source used in the exposure apparatus is a cause of hindering accurate exposure.

Thus, in the present embodiment, the anode 4 disposed in the discharge vessel 2 is provided with a reflection suppressing means for suppressing reflection of light generated by arc discharge generated between the cathode 3 and the anode 4. It is. This reflection suppressing means suppresses the light generated by the arc discharge from being reflected by a part of the anode 4. As shown in FIGS. 3 and 4, the electrode axis P of the anode 4 is used. _2, the reflection suppressing groove portion 31 is formed on the outer peripheral surface 22 a of the anode diameter-reduced portion 22 that is inclined with respect to ₂ .

In the present embodiment, as shown in FIG. 3, the reflection suppressing groove 31 is continuously continuous in the circumferential direction of the outer peripheral surface 22 a of the anode reduced diameter portion 22 around the electrode axis P ₂ of the anode 4. It is formed in a ring shape. A plurality of grooves 31 around the electrode axis P ₂ of the anode 4 is formed on the outer circumference of the anode reduced-diameter portion 22, as shown in FIGS. 3 and 4, sequentially in the direction of the electrode axis P ₂ of the electrode 4 The outer peripheral surface 22a of the anode reduced diameter portion 22 is formed in a multi-stage shape with different diameters.

  Since the reflection suppressing groove 31 is formed for the purpose of suppressing light reflection by the outer peripheral surface 22a of the anode reduced diameter portion 22, as shown in FIGS. 22 is formed on substantially the entire outer peripheral surface 22a from the distal end portion to the proximal end portion side.

Then, the groove 31 for reflection suppression, as shown in FIG. 4, the side surface 31c of the cross-sectional shape centered on the electrode axis P ₂ of the anode 4, around the bottom portion 31a opposed toward the opening 31b side , 31d are formed to have a triangular cross section.

Further, the outer peripheral surface 22a of the anode reduced-diameter portion 22, the groove 31 formed in the triangular cross-section, as shown in FIG. 4, is a direction toward the bottom 31a from the center O ₁ of the opening width of the opening 31b The groove portion direction S ₁ is formed so as to be inclined in a direction from the direction H ₁ perpendicular to the outer peripheral surface 22 a of the anode reduced diameter portion 22 inclined with respect to the electrode axis P ₂ of the anode 4 toward the outer peripheral surface 21 a side of the anode body 21. Is done.

That is, the groove 31 is formed at an angle θ _1, which is an angle formed by the groove direction S ₁ and the outer peripheral surface 22 a of the anode diameter-reduced portion 22, smaller than 90 °, as shown in FIG. Further, it is formed to be inclined toward the base end side of the anode body 21 from the direction H ₁ perpendicular to the outer peripheral surface 22 a of the anode diameter-reduced portion 22. Groove 31 which is thus formed, the other side surface 31d side in the depth direction is located on the inner peripheral side of the electrode axis P ₂ side with respect to one side surface 31c located on the outer peripheral side of the anode reduced-diameter portion 22, i.e. It is formed by increasing the height of the groove direction S ₁ of the groove 31. Therefore, the groove part 31 is formed so that the cross-sectional shape forms an unequal triangle.

  As shown in FIG. 5, the reflection-suppressing groove 31 formed in this way is formed with the opening 31 b directed toward the region in which arc discharge occurs between the cathode 3 and the anode 4. More specifically, as shown in FIG. 5, the groove 31 is formed so that the opening 31 b opens toward the tip surface 18 of the cathode 3 which is one starting point of arc discharge.

By forming the groove portion 31 in this way, light L ₁ that is emitted around the bright spot H of the tip surface 18 of the cathode 3 and emitted toward the outer peripheral surface 22 a of the anode diameter-reduced portion 22 is incident on the groove portion 31. The

Here, the light L ₁ emitted centering on the bright spot H of the tip surface 18 of the cathode 3 is made easy to enter the reflection suppressing groove 31 formed on the outer peripheral surface 22 a of the anode diameter-reduced portion 22. Therefore, it is desirable to form the groove 31 in the following relationship.

  In the example illustrated in FIG. 5, the groove portion 31 formed in the substantially central portion of the plurality of groove portions 31 formed on the outer peripheral surface 22 a of the anode reduced diameter portion 22 will be described as an example.

That is, as shown in FIG. 5, the groove 31 has a distance between the electrodes, which is a distance between the tip surface 18 of the cathode 3 and the tip surface 23 of the anode 4, D, and a diameter of the tip surface 23 of the anode 4 R, The angle formed by the groove direction S ₁ and the electrode axis P _{1 of the} cathode 3 coaxial with the electrode axis P _{2 of the} anode 4 is θ _2, and the bright spot H that is the center of the tip surface 18 of the cathode 3 and the anode 4 The angle formed by the imaginary line S ₂ passing through the outer peripheral edge X ₁ of the tip surface 23 and the electrode axis P _{2 of the} anode 4 is θ _3, and the outer peripheral surface 22 a of the anode reduced diameter portion 22 and the electrode axis P _{2 of the} anode 4 are There when the angle and theta _4, formed so as to satisfy the equations 1 to 3 below.

tan θ ₃ = (R / 2) / d (1)
θ ₃ <θ ₄ (2)
0 ° ≦ θ ₂ <θ ₄ (3)
By forming the groove 31 in this manner, the opening 31 b of the groove 31 faces the arc discharge side generated between the cathode 3 and the anode 4, and the center of the front end surface 18 of the cathode 3 is emitted as a bright spot H. Light L1 can be easily incident.

Incidentally, the groove 31 for reflection suppression, light L ₁ incident on the groove 31, the side surface 31c opposed constituting the groove 31, repeatedly reflected between the 31d, it is absorbed gradually therein, the groove It is formed so as to attenuate the light emitted to the outside of 31. Here, the side surface 31c facing each of the grooves 31, 31d, as described above, constitute the light reflecting means to repeat the reflection of light L ₁ incident on the groove 31.

Groove 31 for attenuating thus incident light L _1, as shown in FIG. 6, the side surface 31c of the light L ₁ entering from the opening 31b side is opposite the bottom 31a side by repeatedly reflected 31d It is formed so as to progress. That is, the groove part 31 is formed so that the space | interval of the side surfaces 31c and 31d which oppose each other toward the bottom part 31a from the opening part 31b side becomes small gradually. In this embodiment, the groove 31, as shown in FIG. 6, and the depth D ₂ to the width W ₂ of the opening 31b is formed in an elongated triangular shape and four times.

Then, the light L ₁ incident on the groove 31 is attenuated by entering the inside of the groove 31 while being repeatedly reflected by the opposite side surfaces 31 c and 31 d as shown by arrows in FIG. 6 and reflected outside the groove 31. The amount of returned light is suppressed.

Incidentally, the grooves 31, among the components of the light L ₁ incident on the groove 31, to suppress the amount of return light reflected back to the outside of the groove 31, opposing sides 31c, the groove while being repeatedly reflected between 31d 31 for increasing the amount of light traveling therein as shown in FIG. 4, opposing sides 31c, it is desirable to reduce the opening angle theta ₅ between 31d. The groove 31, it is desirable to form the opening angle theta ₅ as 30 ° or less.

Groove 31 for reflection suppressing used in this embodiment, any be any shape capable of suppressing reflected light amount while increasing the amount of incident light L ₁ incident on the outer circumferential surface 22a of the anode reduced-diameter portion 22 It may be in the form, for example, as shown in FIG. 7, as opening angle theta ₆ of the bottom portion 31a side is smaller than the opening angle theta ₇ of the opening 31b side, opposing side faces 31c, the 31d depth It is formed to be bent in the middle of the direction. That is, the groove part 31 is formed so that the cross-sectional shape that becomes narrow at a steep angle from the middle in the depth direction toward the bottom part 31a is substantially Y-shaped. Groove 31 formed in a substantially Y-shape as described above, since the larger the width of the opening 31b side, the amount of incident light L ₁ emitted toward the outer surface 22a of the anode reduced-diameter portion 22 greatly, can be attenuated is advanced toward the light L ₁ which is the incident on reliably bottom 31a.

Further, as shown in FIG. 8, the reflection suppressing groove 31 is formed by curving the opposing side surfaces 31c and 31d so as to gradually bulge toward the bottom 31a, and the opening angle on the opening 31b side. theta ₉ is formed to be larger than the opening angle theta ₈ of the bottom portion 31a side. Since even the groove 31 shown in FIG. 8 has a larger width of the opening 31b side, light L incident amount of light L ₁ emitted toward the outer surface 22a of the anode reduced-diameter portion 22 is increased, that is the incident ₁ can be surely entered and attenuated toward the bottom 31a.

In this embodiment, the groove 31 for reflection suppression, the outer peripheral surface 22a of the anode reduced-diameter portion 22, are formed in multiple stages in the electrode axis P ₂ direction, the peripheral of the outer peripheral surface 22a of the anode reduced-diameter portion 22 It may be formed as a single spiral groove that is continuous in the circumferential direction.

  The reflection suppressing groove 31 can be formed using a laser processing method using laser light, a mechanical cutting processing means, or a processing means such as an etching method.

  In the present embodiment, in order to increase the amount of heat radiation of the anode 4 and prevent an excessive temperature rise, as shown in FIGS. 1 and 2, a heat radiating groove on the outer peripheral surface 21 a of the anode body 21. 45 is formed. The heat radiating groove 45 is formed in a shape that enlarges the surface area of the outer peripheral surface 21a of the anode body 21 and increases the amount of heat radiation from the outer peripheral surface 21a of the anode body 21, for example, a triangular cross section, Alternatively, it is formed in an appropriate shape such as a U-shaped cross section.

  In the embodiment described above, the anode 4 is formed by integrally forming the anode body portion 21 and the anode reduced diameter portion 22 in which the reflection suppressing groove portion 31 is formed of the same metal material. The cylindrical cylindrical body 21 and the truncated cone-shaped anode diameter-reduced portion 22 may be butted and joined together. Thus, by forming the anode body part 21 and the anode diameter-reduced part 22 independently, materials required for the respective characteristics can be used. For example, the anode reduced diameter portion 22 that is significantly heated is formed of a high melting point material such as pure tungsten, and the anode body portion 21 is made of a material having excellent thermal conductivity, such as tungsten alloy containing rhenium in tungsten, aluminum nitride, carbon, etc. It is made of molybdenum, which is lighter than tungsten, or an alloy containing molybdenum as a main component.

  By forming the anode body 21 and the anode diameter-reduced part 22 independently, the groove part 45 formed in the anode body part 21 and the anode diameter-reduced part 22 with different shapes and sizes according to the respective characteristics, 31 can be formed easily. For example, the heat dissipation groove 45 having a shape and size excellent in the heat dissipation effect formed in the anode body 21 and the reflection suppressing groove 31 formed in the anode diameter-reduced portion 22 are formed in independent processes. This also makes it possible to facilitate the processing of the groove portions 45 and 31.

  When the anode 4 is configured by independently forming and combining the anode body 21 side portion and the anode reduced diameter portion 22 side portion, the base end portion side portion of the anode reduced diameter portion 22 having a truncated cone shape is formed. It may be formed integrally with the anode body 21, the tip side portion of the anode reduced diameter portion 22 is independently formed, and these are butted and integrated. That is, in the anode 4, a joining surface is formed in the middle portion of the anode reduced diameter portion 22 having a truncated cone shape.

  Furthermore, the cathode 3 may also be formed by abutting and joining a cathode body portion 15 and a cathode reduced diameter portion 16 formed independently. At this time, the cathode body 15 is made of pure tungsten or molybdenum, and the cathode diameter-reduced portion 16 is made of triated tungsten, thereby reducing the amount of thorium (Th) that is a radioactive substance.

  In the case where the cathode 3 is configured by independently forming and combining the cathode body portion 15 side portion and the cathode reduced diameter portion 16 side portion, the base end side portion of the truncated cone diameter portion 16 having a truncated cone shape is used as the cathode. It may be formed integrally with the body portion 15, the tip side portion of the cathode reduced diameter portion 16 is formed independently, and these are butted and integrated. That is, in the cathode 3, a joining surface is formed in the middle part of the cathode reduced diameter portion 16 having a truncated cone shape.

  As shown in the above-described embodiments, the present invention is a short arc type discharge lamp, and is useful when applied to a vertical lighting type discharge lamp in which an anode and a cathode are arranged to face each other in a vertical positional relationship. However, the same advantages as those obtained by applying other discharge lamps can be obtained.

  Moreover, in this invention, the groove part which comprises a reflection suppression means is not specified to what is shown in embodiment mentioned above, In the range which does not change the summary of this invention, it can select suitably.

DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Discharge vessel 3 Cathode 4 Anode 15 Cathode body part 16 Cathode diameter reduction part 18 End face of cathode diameter reduction part 21 Anode body part 22 Anode diameter reduction part 23 End face of anode diameter reduction part 31 Groove part for reflection suppression 31a Bottom part of groove part 31b Opening part of groove part 31c, 31d Side surface of groove part

Claims (6)

A discharge vessel;
Provided with a cathode and an anode disposed in the discharge vessel with the tip portions facing each other at a predetermined interval,
A discharge lamp characterized in that the anode is provided with reflection suppressing means for suppressing reflection of light generated by arc discharge generated between the cathode and the anode.   2. The discharge lamp according to claim 1, wherein the reflection suppressing means is provided in a direction of arc discharge generated between the cathode and the anode. The anode has a cylindrical body portion and a distal end surface, and the outer diameter is gradually reduced from the base end side continuous to the body portion toward the distal end portion where the distal end surface is formed. A reduced diameter portion,
The cathode has a cylindrical body part, and a reduced diameter part gradually reducing the outer diameter from the base end side continuous to the body part toward the distal end part,
3. The discharge lamp according to claim 1, wherein the reflection suppressing means is provided in a reduced diameter portion of the anode.   The reflection suppressing means is formed with a light reflecting means that repeats reflection of incident light generated by arc discharge generated between the cathode and the anode, and a groove portion that suppresses reflection to the outside of the reflection suppressing means. The discharge lamp according to any one of claims 1 to 3, characterized by comprising:   The reflection suppressing means is formed as a groove portion that gradually decreases in width from the opening side where the light generated by the arc discharge generated between the cathode and the anode enters to the bottom side. The discharge lamp according to any one of claims 1 to 4, characterized in that: 6. The discharge lamp according to claim 5, wherein the groove portion constituting the reflection suppressing means has an opening angle on the opening side larger than an opening angle on the bottom side.