JP6707345B2 - Discharge lamp - Google Patents

Description

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

Conventionally, a short arc type discharge lamp that generates ultraviolet rays has been used as a light source used when forming a semiconductor wiring pattern. This type of discharge lamp is lit in a vertical state with the anode above or below. When the discharge lamp is in a lighting state, the anode may be heated to a temperature at which electrons from the cathode collide with each other and a part of the material forming the anode is melted. When the temperature of the anode rises to such a temperature, a part of the material forming the anode becomes fine particles and evaporates in the discharge vessel. The evaporated fine particles are carried by the thermal convection generated in the discharge container and adhere to the inner wall of the discharge container to blacken the inner wall of the discharge container and reduce the amount of light emitted to the outside.

Then, when a part of the anode is melted and evaporated, the tip portion of the anode is consumed and deformed, and stable radiation of light by arc discharge becomes impossible. As a result, the service life of the discharge lamp is shortened.

In order to suppress the wear and deformation of the anode that affects the service life of such a discharge lamp, it is possible to prevent the anode from reaching a temperature at least higher than the melting temperature of the material forming the anode during lighting of the discharge lamp. desirable.

Therefore, in the electrode used in the discharge lamp, particularly the anode, the amount of heat radiated from the anode is increased to suppress the temperature from rising. In order to increase the amount of heat released by such radiation, the surface area of the anode is increased.

A discharge lamp in which the surface area of the anode is increased and the heat radiation from the anode is increased is disclosed in JP 2008-235129 A (Patent Document 1) and JP 2008-235128 A (Patent Document 2). Things have been proposed.

The discharge lamp disclosed in Patent Document 1 has a plurality of grooves having a substantially V-shaped cross section and stepwise side surfaces on one side of a pair of electrodes arranged in a discharge vessel, for example, on the peripheral surface of an anode. It was formed.

Further, the discharge lamp disclosed in Patent Document 2 is formed as a substantially V-shaped groove portion that expands the surface area on one surface of the pair of electrodes arranged in the discharge vessel, for example, the surface of the anode. A heat dissipation structure is provided. This heat dissipation structure expands the surface area of the anode by providing on the side surface an uneven surface composed of a plurality of lumps and holes formed by melting and moving a part of the material forming the electrode. is there.

In the discharge lamps disclosed in Patent Documents 1 and 2, by increasing the surface area of the anode surface, the amount of heat radiated from the anode can be increased, the temperature rise of the anode can be suppressed, and the tip of the anode can be consumed and consumed. It is possible to prevent deformation and prolong the service life.

JP, 2008-235129, A JP, 2008-235128, A

By the way, when a stepwise side surface is provided inside the groove in order to increase the surface area of the electrode like the groove disclosed in Patent Document 1, a sharpened sharp tip may occur on the side surface. .. Electrons due to arc discharge are concentrated on the sharp tip at the start of lighting, and the temperature becomes high, which causes electrode wear.

Then, when the groove having the stepwise side surface is formed by laser processing formed by irradiation of laser light, a part of the material forming the electrode adheres to the processed surface as debris that is a processing scrap. The debris becomes fine particles when the discharge lamp is turned on and scatters and adheres to the inner wall of the discharge container, which causes the inner wall of the discharge container to become black. Therefore, after the groove is processed, it is necessary to perform processing such as polishing for removing debris, which may increase the processing cost.

Further, since the lump formed on the side surface forming the heat dissipation structure disclosed in Patent Document 2 is formed by melting and moving a part of the material forming the electrode, the surface of the lump is formed. In some cases, a part of the electrode material may be attached as debris. Such debris becomes fine particles from the electrode surface when the discharge lamp is turned on and scatters and adheres to the inner wall of the discharge container, which causes blackening of the inner wall of the discharge container. Therefore, after the heat dissipation structure is processed, a process such as polishing for removing this kind of debris is required, which may increase the processing cost.

Therefore, it is an object of the present invention to provide a discharge lamp that suppresses temperature rise of electrodes arranged in a discharge vessel, suppresses wear and deformation of the electrodes, and reduces blackening of the inner wall of the discharge vessel.

The present invention proposed to achieve the above-mentioned technical problem is a discharge lamp including a discharge vessel and a pair of electrodes arranged in the discharge vessel with their tip portions facing each other with a predetermined interval. is there. At least one of the pair of electrodes forming the discharge lamp is provided with a heat radiation fin that is continuous in a circumferential direction of the electrode, and at least a part of the top of the heat radiation fin has a heat radiation fin. At least a part of the material constituting the above is integrated to provide the extending portion. The extending portion has a surface that is continuous with the side surface of the heat dissipation fin.

The extending portion is formed so as to protrude from the top of the heat dissipation fin in the radial direction of the electrode on which the heat dissipation fin is formed.

Here, at least a part of the extending portion is formed so as to protrude from a peripheral surface of the electrode where the heat radiation fin is not formed.

Further, the extending portion is circumferentially provided along the circumferential direction of the electrode provided with the heat radiation fins.

In the present invention, the angle (θ ₁ ) formed by the surface located on one side in the electrode axis direction and the surface located on the other side in the cross section of the extending portion in the electrode axial direction is the electrode of the heat dissipation fin. The heat radiation formed in parallel to the electrode axis direction is formed to be larger than the angle (θ ₂ ) formed by the surface located on one side in the axial direction of the electrode and the surface located on the other side in the axial direction. The space for the fins is widened.

Further, it is desirable that the extending portion has a density lower than that of the heat radiation fin.

In the present invention, it is desirable that the surface of the heat radiation fin located on one side of the electrode axial direction and the surface located on the other side thereof be formed as a continuous surface.

Further, it is preferable that an extension portion forming surface is formed on the top of the heat dissipation fin, and the extension portion is formed on the extension portion forming surface.

The present invention expands the heat radiation area by providing the extended portion for projecting the tip side of the heat radiation fin on the top of the heat radiation fin provided on the electrode, further increases the heat radiation from the electrode, The temperature rise can be suppressed, the consumption and deformation of the electrode can be suppressed, and the service life of the discharge lamp can be extended.

Since the extending portion provided on the top of the heat dissipation fin is provided in a circumferential shape along the circumferential direction of the electrode, the electrode can be cooled uniformly along the circumferential direction.

Further, by widening the space of the heat radiation fins, it becomes easy for heat to diffuse between the heat radiation fins adjacent to each other in the electrode axis direction, and it is possible to suppress heat from staying between the heat radiation fins. Efficient heat radiation is realized.

Furthermore, by making the density of the stretched portion lower than the density of the heat radiation fins, the surface area of the stretched portion is increased, and more efficient heat radiation is realized.

Furthermore, since each surface of the heat dissipation fin is formed as a continuous surface, a part of the material forming the heat dissipation fin is scattered as debris and blackens the inner wall of the discharge vessel during lighting. Suppress it.

Since the extending portion is formed on the extending portion forming surface provided on the top portion of the heat radiating fin, it can be integrated with the heat radiating fin, and the heat radiating effect of the heat radiating fin can be further improved.

Further, the advantages obtained by the present invention will be more apparent than the modes 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 anode used for this invention. It is sectional drawing which shows the anode used for this invention. FIG. 4 is a partial cross-sectional view of the anode schematically showing a portion of the anode body portion of the anode where the heat radiation fins are provided. It is sectional drawing which shows the relationship between a fin for heat radiation and an extension part. It is sectional drawing which shows the other example of a fin for heat radiation and an extension part.

Hereinafter, an embodiment in which the present invention is applied to a short arc type discharge lamp will be described with reference to the drawings.

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

First and second sealing tubes 5 and 6 made of quartz glass are integrally formed with the discharge vessel 2 at opposite positions of the discharge vessel 2 so as to project toward the outside 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 diameter smaller than the outer diameter of the discharge vessel 2 with their central axes P ₀ aligned with each other. There is. 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.

A cathode support shaft 9 having a cathode 3 attached to its tip is inserted and supported in the first sealing tube 5, and an anode support shaft having an anode 4 attached to its tip is inserted in the second sealing tube 6. 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.

Then, as shown in FIG. 1, 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. 1, the anode 4 is also attached with the electrode axis P ₂ that is the central axis of the anode 4 aligned 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 arranged in the discharge vessel 2 with their tip portions facing each other with a predetermined gap in a state where the electrode axes P ₁ and P ₂ are coaxial with each other. To be done.

The cathode support shaft 9 and the anode support shaft 10, which respectively support the cathode 3 and the anode 4, are connected via conductive metal foils 11 and 12 arranged in the first and second sealing tubes 5 and 6, respectively. , Are electrically connected to lead shafts 13 and 14 disposed on the bases 7 and 8.

Although not shown, the first and second sealing pipes 5 and 6 are sealed by being melted by heat fusion with a glass material for sealing which is housed and arranged in these sealing pipes 5 and 6. The discharge space DS formed in the discharge vessel 2 is sealed. The sealed discharge space DS in the discharge vessel 2 is filled with mercury and a rare gas such as xenon and argon.

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

The cathode 3 used in the discharge lamp 1 according to the present embodiment is formed by using a refractory metal material such as tungsten or an alloy containing tungsten as a main component. The cathode 3 made of a sintered body of tungsten has a cathode body portion 15 which is a mounting portion side of the cathode support shaft 9 on the base end side and a cathode reduced diameter portion which is an electron emitting portion side on the tip end side. 16 are formed.

The cathode body portion 15 is formed in a cylindrical shape having a constant outer 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 cathode 3 is electrically connected to the cathode support shaft 9 and mechanically fixedly supported by fitting the support shaft fitting hole 17 into the tip end portion of the cathode support shaft 9. Since the cathode 3 is attached by fitting the support shaft fitting hole 17 formed so that the central axis thereof coincides with the electrode shaft P ₁ with the cathode supporting shaft 9, the electrode shaft P ₁ is attached to the cathode 3 as shown in FIG. It is arranged in the discharge vessel 2 so as to be aligned with the central axis of the support shaft 9 and the central axis P ₀ of the first sealing tube 5.

The cathode reduced diameter portion 16 is formed in a substantially conical shape in which the diameter is gradually reduced from the base end portion side that is a continuous portion to the cathode body portion 15 toward the tip end portion side that is an electron emission portion. The tip end side of the cathode reduced diameter portion 16 is formed to be sharpened in order to realize concentrated and stable electron emission. In the present embodiment, the tip portion of the cathode reduced diameter portion 16 has a certain area by cutting out a part of the sharp tip portion in order to prevent wear due to excessive temperature rise due to concentration of arc discharge. A circular tip surface 18 having a is formed.

On the other hand, the anode 4 used in the present embodiment is formed of tungsten which is a refractory metal material or an alloy whose main component is tungsten. As shown in FIG. 2 and FIG. 3, the anode 4 made of a sintered body of tungsten 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 3 on the tip end side. The cathode reduced diameter portion 16 and the anode reduced diameter portion 22 facing each other are provided.

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

The anode reduced diameter portion 22 is formed so as to form a conical shape in which the diameter is gradually reduced from the base end portion side that is continuous with the body portion 21 toward the tip end portion side. A circular tip surface 23 is formed at the tip of the anode reduced diameter portion 22. The tip surface 23 is formed in a concentric circle centered on the electrode axis P ₂ . Further, the front end surface 23 of the anode 4 constitutes a discharge surface for generating an arc discharge with the front end surface 18 serving as the 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 bored from the base end side of the anode body 21 to the middle part of the tip end with the center axis thereof aligned with the electrode axis P ₂ of the anode 4. The anode 4 is electrically connected to the anode support shaft 10 and mechanically fixedly supported by fitting the support shaft fitting hole 24 into the tip end portion of the anode support shaft 10. At this time, the anode 4 is attached by fitting the support shaft fitting hole 24 formed so that the central axis thereof coincides with the electrode shaft P ₂ with the anode supporting shaft 10, so that as shown in FIG. ₂ is arranged in the discharge vessel 2 with the center axis of the anode support shaft 10 and the center axis P ₀ of the second sealing tube 6 aligned.

As described above, the cathode 3 and the anode 4 are attached respectively to match the central axis in the first and second sealing tube 5, 6 formed in the discharge vessel 2 by matching the central axis P ₀ of 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).

The cathode 3 and the anode 4 have a tip surface 18 of the cathode 3 and a tip surface of the anode 4 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. It is positioned so that the inter-electrode distance D formed with 23 is maintained at a constant distance.

By the way, the anode 4 used in the short arc type discharge lamp 1 is heated to a temperature higher than that of the cathode 3 due to collision of electrons from the cathode 3 when the discharge lamp 1 is in a lighting state. Therefore, as shown in FIG. 1, the anode 4 is formed in a large size having a volume sufficiently larger than that of the cathode 3 in order to increase the heat capacity and suppress an excessive temperature rise.

The anode 4 used in the discharge lamp 1 according to the present embodiment is provided with a heat dissipation mechanism 31 in order to increase the amount of heat emitted from the anode 4 and prevent an excessive temperature rise. In the present embodiment, the heat dissipation mechanism 31 is provided on the peripheral surface (outer peripheral surface) of the columnar anode body portion 21, as shown in FIGS. As shown in FIGS. 2 and 3, the heat dissipation mechanism 31 includes a plurality of heat dissipation fins 32 formed on the peripheral surface (outer peripheral surface) of the anode body 21, and the heat dissipation fins 32 have a top end on the tip side. An extension portion 34 is provided at 33. In the present embodiment, the extending portion 34 is formed integrally with the heat radiation fin 32, as shown in FIG.

The plurality of heat dissipating fins 32 forming the heat dissipating mechanism 31 are formed on the peripheral surface of the anode body 21 in a circumferential shape that is continuous in the circumferential direction of the anode 4 about the electrode axis P ₂ of the anode 4. As shown in FIGS. 2 and 3, the electrode shaft P ₂ is formed in multiple stages in the axial direction. As shown in FIG. 4, each of the heat radiation fins 32 is formed so as to become narrower from the base end side located on the electrode axis P ₂ side of the anode body 21 toward the tip end side. There is. A flat extending portion forming surface 35 having a constant width and a constant area is provided at the tip of the top portion 33 in which the heat radiation fins 32 are narrowed. On the extended portion forming surface 35, an extended portion 34 is formed so as to protrude in the radial direction of the anode body portion 21. As shown in FIG. 4, the extending portion 34 is formed so as to be sharpened from the extending portion forming surface 35 side toward the tip side.

Here, the heat radiation fins 32 and the extending portions 34 formed on the top portions 33 of the heat radiation fins 32 are formed by performing laser processing on the peripheral surface of the anode body portion 21. The laser processing for forming the fins 32 for heat dissipation and the extension portion 34 is emitted from the laser light source to the peripheral surface of the anode body portion 21 while rotating the anode 4 made of a sintered body of tungsten about the electrode axis P _2. The laser light L is irradiated. At this time, while irradiating the peripheral surface of the anode body portion 21 while controlling the power area density of the laser light and the irradiation time, as shown in FIGS. 4 and 5, a part of the tungsten which is the material forming the anode 4 is To be melted. As shown in FIG. 4, the plurality of heat radiation fins 32 formed by melting a part of the anode 4 are discretely formed at regular intervals in the direction of the electrode axis P ₂ . The heat dissipation fin 32 formed here is narrowed from the base end side located on the electrode axis P ₂ side toward the tip end side, and the peripheral surface of the anode body portion 21 is provided at the tip end on the top 33 side. Has a stretched portion forming surface 35 formed by a part of the.

The peripheral surface of the anode body portion 21 may be subjected to processing such as cutting or polishing so as to have a smooth surface in order to improve the accuracy of laser processing.

By the way, when the heat radiation fin 32 is formed by irradiating the circumferential surface of the anode body 21 with the laser light, a part of the material forming the heat radiation fin 32 is melted and evaporated. A part of the melted and evaporated material forming the heat dissipation fin 32 is accumulated on the extension part forming surface 35 on the tip end side of the heat dissipation fin 32 to form the extension part 34.

In the present embodiment, the heat dissipation fin 32 is formed by melting a part of the anode 4, and a part of the material forming the heat dissipation fin 32 forming the extending portion 34 is It is also a part of the material forming the anode 4.

Then, a part of the material constituting the heat radiation fins 32 which is melted and evaporated by the irradiation of the laser light is sequentially moved and accumulated on the flat extending portion forming surface 35 having a certain width and a certain area. As a result, as shown in FIG. 5, the extending portion 34 protruding in the radial direction of the anode 4, which is the electrode on which the heat radiation fin 32 is formed, is formed. The extending portion 34 is formed such that the sectional shape in the electrode axis P ₂ direction is sharpened from the extending portion forming surface 35 side toward the tip side.

Here, a part of the tungsten, which is the material that constitutes the melted and evaporated anode 4 that constitutes the stretched portion 34, becomes fine particles and is sequentially accumulated on the stretched portion forming surface 35 to be integrated with the heat radiation fin 32. , Is formed so as to be continuous with the heat radiation fin 32.

In order to surely accumulate the melted and evaporated tungsten fine particles on the stretched portion forming surface 35, the width W ₁ of the stretched portion forming surface 35 in the electrode axis P ₂ direction is 15 μm or more as shown in FIG. Is desirable, and in order to realize reliable integration of the tungsten fine particles accumulated on the stretched portion forming surface 35, it is desirably 50 μm or less.

In this embodiment, the side surface 32b that flank 32a and the other side of which is located on one side of the electrode axis P ₂ direction in the electrode axis P ₂ direction of the cross-section of the radiation fins 32, as shown in FIG. 5 , So as to form a continuous surface. That is, on the side surfaces 32a and 32b that continuously and circumferentially face each other on the outer circumference of the anode body portion 21 of the heat dissipation fin 32, a part of the material of the melted and vaporized anode 4 is attached as debris. As a result, a continuous smooth surface is formed without forming protrusions.

Here, by controlling the power area density and the irradiation time of the laser light with which the anode body portion 21 is irradiated, a part of the material that constitutes the melted and evaporated anode 4 is deposited on the side surfaces 32 a and 32 b of the heat radiation fin 32. It can be formed as a continuous smooth surface without adhering.

Further, since the stretched portion 34 is formed by accumulating tungsten, which is a material forming the anode 4, in the form of fine particles, the stretched portion 34 is formed as a protrusion having a flat surface that does not cause minute protrusions on the surface. Therefore, the side surface 34a located on one side in the electrode axis P ₂ direction and the side surface 34b located on the other side of the extending portion 34 continuous with the side surfaces 32a, 32b of the heat dissipation fin 32 are, as shown in FIG. , A flat surface that is continuous with the side surfaces 32a and 32b of the heat dissipation fin 32. The extending portion 34, which is formed by a surface continuously connected to the side surfaces 32a and 32b of the heat dissipation fin 32 as described above, is integrated with the heat dissipation fin 32 and scatters from the heat dissipation fin 32 during lighting, etc. Suppress blackening of the inner wall.

The amount of material that is melted and evaporated from the anode 4 is controlled by controlling the power area density and the irradiation time of the laser light that is applied to the anode body portion 21, and the amount of material that is accumulated on the stretched portion forming surface 35 is controlled. Can be controlled. By controlling the amount of material that melts and evaporates, the stretched portion 34 formed on the stretched portion forming surface 35 can be formed in a desired size.

Further, since the extended portion 34 formed by laser processing can be formed almost simultaneously with the formation of the heat radiation fin 32, it can be formed easily.

As described above, the extension portion 34 is provided so as to project on the extension portion forming surface 35 of the top portion 33 of the heat dissipation fin 32, so that the surface area of the heat dissipation mechanism 31 including the heat dissipation fin 32 is increased and the heat from the anode 4 is increased. Improve radiation.

In the present embodiment, the extended portion forming surface 35 of the heat dissipation fin 32 on which the extended portion 34 is formed is formed of a part of the peripheral surface of the anode body portion 21. Therefore, as shown in FIG. 4, at least a part on the tip side of the extending portion 34 formed by accumulating a part of the material constituting the anode 4 which has been melted and evaporated on the extending portion forming surface 35 is for heat dissipation. The fins 32 are formed so as to further project in the radial direction of the anode 4 from the peripheral surface 21a of the anode body portion 21 on which the fins 32 are not formed.

The extended portion 34 formed so as to project from the top portion 33 of the heat dissipation fin 32 comes into contact with or approaches the convection of the gas enclosed in the discharge vessel 2, and therefore, the extended portion of the heat dissipation fin 32 in which the extended portion 34 is formed is further formed. Efficient heat exchange can be achieved, and the temperature rise of the anode 4 which rises during lighting can be suppressed.
Then, as shown in FIG. 4, the extending portion 34 has a tip end portion in a radial direction of the anode 4 from the peripheral surface 21 a of the anode body portion 21 which is a surface where the heat radiation fins 32 of the anode body portion 21 are not formed. By projecting, it is possible to further contact or approach the convection of the gas sealed in the discharge vessel 2, and it is possible to realize more efficient heat exchange.

In the present embodiment, the extended portion 34 is melted and evaporated on the extended portion forming surface 35 provided on the top portion 33 of the heat dissipation fin 32 formed in a circumferential shape that is continuous in the circumferential direction of the anode 4. Since the heat dissipation fins 32 are formed by integrating a part of the material, the heat dissipation fins 32 are formed in a continuous circumferential shape in the circumferential direction of the anode 4 provided with the heat dissipation fins 32. By forming the extending portion 34 in a circumferential shape that is continuous in a circumferential direction of the anode 4, it is possible to uniformly cool the anode 4 in the circumferential direction without uneven cooling.

In the present embodiment, the extension portion 34 is formed to have a lower density than the heat radiation fin 32. That is, since the extending portion 34 is formed by accumulating fine particles of tungsten obtained by melting a part of the material forming the anode body portion 21 on which the heat dissipation fins 32 are formed, a minute void is formed from the inside to the surface. A hole is formed. Therefore, the extension portion 34 has a lower density than the heat radiation fin 32 configured by a part of the anode body portion 21 formed as a sintered body of tungsten. Therefore, the density is changed at the boundary between the extended portion forming surface 35 and the extended portion 34 provided on the top portion 33 of the heat dissipation fin 32. The extended portion 34, which has a large number of minute holes and has a lower density than the fins 32 for heat dissipation, has an increased surface area and can radiate heat more efficiently.

In addition, in the present embodiment, as shown in FIG. 5, an angle formed by a side surface 34 a located on one side in the electrode axis P ₂ direction and a side surface 34 b located on the other side, which constitutes the surface of the extending portion 34, is formed. θ ₁ is formed to be larger than the angle θ ₂ formed between the side surface 32 a located on one side of the heat dissipation fin 32 in the electrode axis P ₂ direction and the side surface 32 b located on the other side thereof. As shown, the space S of the heat radiation fins 32 formed in parallel in the direction of the electrode axis P ₂ is widened.

In this way, the space S between the plurality of circumferential fins 32 for heat dissipation is widened, so that the heat can be easily diffused between the fins 32 for heat dissipation and the heat can stay between the fins 32 for heat dissipation. Is suppressed, and efficient heat radiation by the heat radiation fins 32 is realized.

By the way, the extending portion 34 in which the angle θ ₁ formed by the facing side surfaces 34 a, 34 b is larger than the angle θ ₂ formed by the facing side surfaces 32 a, 32 b of the heat dissipation fin 32 is formed by forming the extending portion 34, and 4 can be formed by subjecting 4 to a heat treatment to expel impurities and impure gas contained in the stretched portion 34 to cause shrinkage. The stretched portion 34 from which impurities and impure gas have escaped has improved mechanical strength and can be prevented from being easily damaged by collision with foreign matter.

In the above-described embodiment, the side surfaces 32a and 32b forming the surface of the heat dissipation fin 32 and the side surfaces 34a and 34b forming the surface of the extending portion 34 are formed as flat surfaces. It may be formed as a curved surface that continuously curves as shown.

In the above-described embodiment, the heat dissipation fins 32 have a circumferential shape that is continuous in the circumferential direction of the anode 4 around the electrode axis P ₂ of the anode 4 on the circumferential surface of the anode body portion 21, As shown in FIGS. 2 and 3, the electrodes are formed in multiple stages in the axial direction of the electrode axis P ₂ , but may be continuously formed in a spiral shape in the circumferential direction of the anode 4. By forming the heat radiation fin 32 in a spiral shape, the extending portion 34 formed on the top portion 33 of the heat radiation fin 32 is also formed in a spiral shape in the circumferential direction of the anode 4.

Further, in the above-described embodiment, the heat radiation mechanism 31 in which the extending portions 34 are formed on the top portions 33 of the plurality of heat radiation fins 32 is formed only on the anode body portion 21, but also on the anode reduced diameter portion 22. It may be formed. By forming the anode reduced diameter portion 22, the heat dissipation effect can be further enhanced.

In the short arc type discharge lamp, the discharge mechanism 31 described above may be provided on either the cathode 3 or the anode 4. Further, it may be provided on both the cathode 3 and the anode 4.

In the above-mentioned embodiment, the example in which the anode in which the entire electrode is integrally formed of the tungsten alloy is used is described, but the present invention is limited to the discharge lamp using the integrated electrode as described above. Instead of this, for example, it may be applied to a discharge lamp using a junction type electrode in which an anode body portion and an anode reduced diameter portion, which are independently formed, are integrated by solid-phase joining or the like. By forming the anode body portion and the anode reduced diameter portion independently in this way, it is possible to use materials required for their respective characteristics. For example, the reduced diameter portion of the anode, which is remarkably heated by the incidence of electron flow from the cathode, is formed of a high melting point material, for example, pure tungsten, and the anode body portion is made of a material having excellent thermal conductivity, for example, tungsten containing rhenium in tungsten. It is formed of an alloy, aluminum nitride, a carbon material, or molybdenum or an alloy containing molybdenum as a main component, which is lighter than tungsten.

As described above, in the present embodiment, the melted electrode created when the heat dissipation fin 32 is formed by performing laser processing on the anode 4 which is an electrode formed of tungsten or an alloy containing tungsten as a main component. Since a part of the material is positively used to form the extending portion 34 which is integrated with the heat dissipation fin 32 and enlarges the surface area of the heat dissipation fin 32, when the heat dissipation fin 32 is formed. It is possible to eliminate the need to remove the electrode material that becomes debris generated in the electrode. Therefore, it is possible to simplify additional processing such as polishing processing performed after processing the heat dissipation fins 32, simplify the electrode processing steps, and eventually manufacture the discharge lamp.

The present invention is not limited to the above-described embodiment, and can be appropriately selected without changing the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 discharge lamp, 2 discharge vessel, 3 cathode, 4 anode, 21 anode body part, 31 radiating mechanism, 32 radiating fin, 33 top part of radiating fin, 34 extended part, 35 extended part forming surface

Claims (2)

A discharge vessel,
A discharge space configured in the discharge vessel,
A pair of electrodes arranged in the discharge space formed in the discharge vessel with the tip portions facing each other at a predetermined interval;
At least one of the pair of electrodes is provided with a fin for heat dissipation that is continuous in series along the circumferential direction of the electrode,
An extension portion forming surface having a width in the electrode axial direction of 15 μm or more and 50 μm or less is formed on the top of the heat dissipation fin, and at least a part of the extension portion forming surface is made of a material forming the heat dissipation fin. At least a part of the fins is integrated, and an extending portion that is integrated with the heat-dissipating fin and has a surface that is continuously continuous with the side surface of the heat-dissipating fin is provided.
The extending portion projects from the top of the heat dissipation fin in the radial direction of the electrode on which the heat dissipation fin is formed, rather than the peripheral surface of the electrode on which the heat dissipation fin is not formed. And a discharge lamp. The discharge lamp according to claim 1, wherein the extending portion is provided in a circumferential shape along a circumferential direction of the electrode provided with the heat radiation fins.