JP7076307B2 - Manufacturing method of discharge lamp and electrode for discharge lamp - Google Patents

Description

The present invention relates to a discharge lamp having a pair of electrodes, and more particularly to the internal structure of the electrodes.

In the discharge lamp, the tip of the electrode becomes hot during lighting, the electrode material such as tungsten melts and evaporates, the discharge tube becomes black, and the illuminance of the lamp is lowered. In order to prevent the tip of the electrode from overheating, the tip of the electrode made of a durable metal and the body made of a metal having higher thermal conductivity are separately molded and joined by solid phase bonding or the like. For example, the electrode can be configured by solid phase bonding such as SPS (see Patent Document 1). By joining a plurality of members to form an electrode, it is possible to provide durability even if the electrode is enlarged, and at the same time, it is possible to form an electrode having excellent thermal conductivity.

Japanese Patent No. 5472915

In order to increase the size of the exposed object and improve the throughput, it is required to increase the output (high power) of the lamp. Along with this, the electrode temperature during lighting of the lamp also rises, and it is difficult to effectively suppress electrode overheating by simply solid-phase joining the tip side member and the body portion side member.

Therefore, there is a need for an electrode structure that can effectively suppress the temperature rise of the electrode while the discharge lamp is lit.

The discharge lamp of the present invention includes a discharge tube and a pair of electrodes arranged to face each other in the discharge tube, and at least one of the electrodes has a cylindrical recess along an axial direction facing in the direction opposite to the electrode tip surface side. A columnar portion surrounded by a cylindrical recess and a heat dissipation space formed along the axial direction at least around the side surface of the columnar portion are provided. Here, the "columnar portion" and the "cylindrical recess" are portions defined by including the contact surface or the joint surface when the electrode formed by the joint between the plurality of members is viewed in cross section, for example. It does not matter whether the end face of the columnar portion is in contact with or not in contact with the bottom surface of the tubular recess. The tubular recess is formed in the tip side member having the electrode tip surface, and the columnar portion is formed in the rear end side member connected to the electrode support rod. For example, the central axis of the columnar portion and the cylindrical recess can be configured to coincide with the electrode axis.

Further, the electrode is formed with a through hole connecting the bottom surface of the tubular recess and the tip surface of the electrode. The heat dissipation space can be configured to include a vertical axis heat dissipation space formed along the vertical direction of the axis between the bottom surface of the tubular recess and the end face of the columnar portion. In that case, the through hole is spatially connected to the heat dissipation space in the vertical direction of the axis.

The through hole can be configured to include a spatial region through which the electrode shaft passes. For example, it is possible to form a through hole having a central axis that coincides with the electrode axis.

The electrode can be provided with a heat radiating portion, for example, the heat radiating portion is formed on at least one of the end face and the side surface of the columnar portion. Further, on the bottom surface of the tubular recess, it is possible to form an inclined surface that is inclined in a direction approaching the electrode tip surface toward the through hole.

In the method for manufacturing an electrode for a discharge lamp of the present invention, a cylindrical recess is formed around a central axis for a columnar tip-side solid member having an electrode tip surface, and a through hole is formed around the central axis for the tubular recess. For the solid member on the rear end side of the columnar shape, a columnar portion smaller in size than the tubular recess is formed around the central axis, and the solid member on the tip side is arranged so that the columnar portion is coaxially arranged in the cylindrical recess. Combine with the rear end side solid member and perform solid phase bonding. For example, the front end side solid member and the rear end side solid member are directly solid-phase bonded. Alternatively, it is also possible to perform solid phase bonding by sandwiching an intermediate member between the front end side solid member and the rear end side solid member.

According to the present invention, in a discharge lamp, heat can be effectively dissipated and the electrode temperature can be suppressed.

It is a top view of the discharge lamp which is 1st Embodiment. It is a schematic cross-sectional view of an electrode. It is a figure which showed the part of the manufacturing process of an electrode simplified. It is a schematic cross-sectional view of the electrode which is 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of a discharge lamp according to the first embodiment.

The short arc type discharge lamp 10 is a large discharge lamp capable of outputting high-intensity light, and includes a substantially spherical discharge tube (light emitting tube) 12 made of transparent quartz glass, and the inside of the discharge tube 12 is made of tungsten. A pair of electrodes 20 and 30 are arranged to face each other (coaxially). Quartz glass sealing tubes 13A and 13B are connected to and integrally formed with the discharge tube 12 on both sides of the discharge tube 12. The discharge space DS in the discharge tube 12 is filled with mercury and a rare gas such as halogen or argon gas.

The electrode 20 which is a cathode is supported by the electrode support rod 17A. The sealing tube 13A includes a glass tube (not shown) through which the electrode support rod 17A is inserted, a lead rod 15A connected to an external power source, a metal foil 16A connecting the electrode support rod 17A and the lead rod 15A, and the like. It is sealed. Similarly, for the electrode 30 which is an anode, mounting parts such as a glass tube (not shown) through which the electrode support rod 17B is inserted, a metal foil 16B, and a lead rod 15B are sealed. Further, the bases 19A and 19B are attached to the ends of the sealing tubes 13A and 13B, respectively.

When a voltage is applied to the pair of electrodes 20 and 30, an arc discharge is generated between the electrodes 20 and 30, and light is radiated to the outside of the discharge tube 12. Here, 1 kW or more of electric power is input. The light emitted from the discharge tube 12 is guided in a predetermined direction by a reflecting mirror (not shown). For example, when the discharge lamp 10 is incorporated in the exposure apparatus, the synchrotron radiation becomes pattern light and irradiates the substrate or the like.

FIG. 2 is a schematic cross-sectional view of the electrode (anode) 30. The electrode (cathode) 20 can have the same structure.

The electrode 30 is composed of a rear end side member 32 connected to the electrode support rod 17B and a front end side member 34 having an electrode front end surface 30S, and the electrode 30 is configured by joining the rear end side member 32 and the front end side member 34. ing. Here, the rear end side member 32 and the front end side member 34 are joined by solid phase bonding such as SPS.

The rear end side member 32 is a columnar member having an electrode shaft X (hereinafter, also referred to as an axial direction X) as a central axis, and a columnar portion 50 (here, a columnar shape) protruding toward the electrode tip surface 30S. Is formed. In the tip side member 34, a cylindrical recess 40 surrounding the columnar portion 50 is coaxially formed. The cylindrical recess 40 faces in the direction opposite to the electrode tip surface 30S, that is, is recessed in the opposite direction. The rear end side member 32 is solid-phase bonded to the end portion 34E of the front end side member 34 at the end portion 32E.

Between the columnar portion 50 and the tubular recess 40, a gap 60 is formed over the entire circumference of the columnar portion 50 along the axial direction X and the axial vertical direction perpendicular to the axial direction X. Here, the gap portion along the axis vertical direction is 60D, and the gap portion along the axial direction X is 60V. The gap portions 60D and 60V are spatially connected.

The central axis of both the columnar portion 50 and the cylindrical recess 40 coincides with the electrode axis X, and the shape is symmetrical with respect to the electrode axis X. The bottom surface 40B of the cylindrical recess 40 is also symmetrical with respect to the electrode axis X, and the gap 60 is also symmetrical with respect to the electrode axis X.

The radial width W of the gap portion 60V, that is, the radial distance between the side surface 50S of the columnar portion 50 and the side surface 40S of the tubular recess 40 is shorter than the diameter R of the columnar portion 50 (W <R). The axial width T of the gap portion 60D is the same as the radial width W of the gap portion 60V here, and is shorter than the height H of the columnar portion 50 (T <H). The gap 60 is formed in the electrode 30 and is a bottomed tubular space region.

Here, the radial width W and the axial width T are sufficiently shorter than the diameter R and the height H of the columnar portion 50, respectively, and the side surface 50S and the end surface 50E of the columnar portion 50 are the side surfaces 40S of the tubular recess 40, respectively. The volume of the space formed by the gap 60, which is close to the bottom surface 40B, is smaller than the volume of the columnar portion 50. Further, the gap 60 is not provided with a member such as a heat transfer body.

A through hole 80 is formed in the tubular recess 40 along the electrode shaft X. The through hole 80 has a circular cross section and is formed between the electrode tip surface 30S and the bottom surface 40B of the cylindrical recess 40, and spatially connects the outside of the electrode and the gap 60. Here, the central axis of the through hole 80 coincides with the electrode axis X. The diameter r of the through hole 80 is smaller than the diameter R of the columnar portion 50.

An inclined surface 70 is formed at the end of the through hole 80 on the bottom surface side of the cylindrical recess. The inclined surface 70 is continuously connected to a plane perpendicular to the electrode axis X at the bottom surface 40B of the tubular recess 40, and is inclined in a direction approaching the electrode tip surface 30S, that is, a direction away from the columnar portion 50. The inclined surface 70 is formed as an annular surface symmetrical with respect to the electrode axis X at the end of the through hole 80, and the inclination thereof is constant here.

While the lamp is lit, the temperature of the electrode tip side member 34 rises, and the heat of the electrode tip side member 34 is transferred to the columnar portion 50. Further, since the end surface 50E of the columnar portion 50 is spatially connected to the vicinity of the electrode tip surface 30S, the heat of the arc discharge is directly absorbed by the through hole 80. The heat of the columnar portion 50 is radiated to the gap 60 and transferred to the electrode support rod 17B side. The heat transferred not only in the axial direction X but also in the vertical direction of the axis is transferred from the electrode outer surface 30M to the discharge space DS.

By providing the gap 60 that functions as a heat dissipation space, it is possible to suppress overheating on the electrode tip side. In particular, by making the shape of the portion that dissipates heat to the gap 60 into the columnar portion 50, the surface area is increased, the heat capacity is increased, and the temperature rise of the electrode can be effectively suppressed. Further, since the gap 60 is formed as a bottomed tubular space symmetrical with respect to the electrode axis X, heat can be dissipated evenly in the axial direction X and the axial direction and the circumferential direction of the columnar portion 50, and the electrode It is possible to prevent uneven heat dissipation even with respect to heat dissipation from 30.

The axial width T of the gap portion (radiation space in the vertical direction of the axis) 60D is smaller than the height H of the columnar portion 50 (T <H). As a result, not only the heat capacity of the columnar portion 50 increases, but also the heat of the tip side member 34 (heat of the arc discharge) is easily transferred to the columnar portion 50. Further, heat can be quickly transported from the columnar portion 50 (end face 50E) to the rear end side member 32. On the other hand, the radial width W of the gap portion 60V is set to be smaller than the diameter R of the columnar portion 50 (W <R). As a result, not only the heat capacity of the columnar portion 50 increases, but also the heat of the columnar portion 50 (side surface 50S) is easily transferred to the electrode outer surface 30M side via the cylindrical recess 40 (side surface 40S).

Further, in the present embodiment, a through hole 80 is formed from the electrode tip surface 30S toward the columnar portion 50. As a result, the arc discharge is stabilized around the space region of the through hole 80. In particular, since the diameter r of the through hole 80 is smaller than the diameter R of the columnar portion 50, the arc discharge tends to concentrate in the through hole 80. As a result, the fluctuation of the arc discharge is suppressed and the illuminance is increased. Further, since the vicinity of the center of the electrode tip surface 30S is open, the electrode tip surface 30S is prevented from being consumed, and the lamp life is extended. Since the diameter R of the columnar portion 50 is larger than the diameter r of the through hole 80 and the central axes thereof coincide with each other, the columnar portion 50 is likely to receive heat from the arc discharge. Further, the gas in the discharge space DS flows in and out of the electrode through the through hole 80. As a result, the temperature rise inside the electrode can be suppressed.

On the other hand, the through hole 80 functions as a hole for discharging the cleaning liquid in the electrode cleaning during the electrode manufacturing process. In particular, by providing the inclined surface 70, it is possible to prevent the cleaning liquid from remaining and the discharge tube from becoming dirty.

An electrode having the above characteristics can be manufactured as follows.

FIG. 3 is a diagram showing a part of the electrode manufacturing process in a simplified manner.

First, a through hole 80 is formed around the central axis with respect to the bottom surface of the tip side member 34 having the cylindrical recess 40 formed in the direction perpendicular to the electrode axis. Further, an inclined surface 70 is formed around the central axis of the through hole 80 with respect to the bottom surface side end portion. Then, the rear end side member 32 having a columnar portion 50 accommodating in the tubular recess 40 and forming the insertion hole 32B for the electrode support rod and the front end side member 34 are solid-phase bonded. At this time, the columnar portion 50 is joined so as to be coaxially arranged in the cylindrical recess 40. An intermediate member may be sandwiched between the front end side member 34 and the rear end side member 32 for joining. Metal powder or the like may remain inside the electrode (inside the tubular recess 40) or on the surface of the electrode due to solid phase bonding, or dirt may be attached to the electrode. To remove this, electrode cleaning is performed after solid phase bonding. Specifically, the electrodes are washed with a cleaning solution containing water or an alcohol component. For example, ultrasonic cleaning can be applied. Since the gap 60 is spatially connected to the outside of the electrode through the through hole 80, the cleaning liquid enters the gap 60.

After cleaning, the electrode tip surface 30S is on the lower side, and the bonded electrode is dried. The cleaning liquid remaining in the gap 60 (indicated by the reference numeral “K” in FIG. 3) flows down to the bottom surface 40B of the tubular recess 40, flows into the through hole 80 through the inclined surface 70, and flows to the outside of the electrode as it is. As a result, the cleaning liquid remaining inside the electrode is discharged to the outside of the electrode. When the drying process is completed, heat treatment is performed according to the specified time and temperature. After the heat treatment, the electrode support rod 17B is inserted into the insertion hole 32B. In FIG. 3, the front end side member 34 and the rear end side member 32 are processed into an electrode shape before joining, but electrode shape processing such as forming a truncated cone portion after joining may be performed. The metal powder and dirt at this time may be cleaned.

The through hole 80 may be chamfered (for example, the angle at which the through hole and the tip surface of the electrode are connected). Further, the shape of the inclined surface 70 is not limited to the annular surface (tapered surface) having a constant angle, and can be a curved surface shape, and the bottom surface 40B of the cylindrical recess 40 is made an inclined surface as a whole. May be good.

As described above, according to the present embodiment, in the electrode 30 in which the distal end side member 34 in which the tubular concave portion 40 is formed and the rear end side member 32 in which the columnar portion 50 is formed are solid-phase bonded, the cylindrical concave portion 40 and the columnar shape are formed. A gap 60 is formed between the portion 50 and the portion 50. At the same time, a through hole 80 that spatially connects the electrode tip surface 30S and the bottom surface 40B of the cylindrical recess 40, that is, the gap 60 is formed along the electrode shaft X. The columnar portion 50 (end surface 50E) may be in contact with the bottom surface 40B of the tubular recess 40 without providing the gap 60D between the tubular recess 40 and the columnar portion 50.

Next, the discharge lamp according to the second embodiment will be described with reference to FIG. In the second embodiment, an electrode having a heat dissipation structure (hereinafter, also referred to as a heat dissipation portion) is configured.

FIG. 4 is a cross-sectional view of the electrode 130 (anode) according to the second embodiment. The cathode can have the same structure.

A heat radiating portion 210 is formed on the side surface of the rear end side member 132 over the entire circumferential direction. For example, it is possible to form a heat radiating portion 210 having a layer such as an oxide film formed by an alumina blast treatment or the like. On the other hand, heat radiating portions 250 and 240 are formed on the side surface 140S and the tapered surface 140M of the tip side member 134 in the circumferential direction. The heat radiating portions 240 and 250 can be formed as recesses formed by, for example, electric discharge, laser, or cutting.

On the side surface 150S of the columnar portion 150, a recess is formed as a heat radiating portion 220 along the entire circumference along the circumferential direction, and is formed in the axial direction X with a length corresponding to the height of the columnar portion 150. .. The formation position of the heat dissipation portion 250 of the tip side member 134 corresponds to the formation position of the heat dissipation portion 220, and has a double heat dissipation structure. The heat radiating portion 220 can be formed by means such as laser or cutting. However, a heat dissipation structure (heat dissipation part) may be realized by a configuration other than the recess, and the side surface 150S is covered with a known surface area increasing structure or a heat dissipation material (for example, a heat dissipation layer of a carbonized film or an oxide film). May be good. Further, a member having a high emissivity such as a carbon nanotube can also be applied.

A heat radiating portion 230 having a fine recess is also formed on the end surface 150E of the columnar portion 150. The heat radiating portion 230 is formed as a number of rings around the central portion (in the circumferential direction). As a result, the heat absorption of the arc discharge can be enhanced, the heat can be efficiently dissipated to the gap 160, and the heat can be efficiently transported to the electrode support rod side. However, the heat radiating portion 230 may be formed radially (diameterally) with respect to the end face 150E.

By providing such heat radiating portions 210, 220, 230, 240, 250, heat can be effectively released to the outside of the electrode. However, the heat radiating portions 210, 220, 230, 240, and 250 can be formed at other positions. Further, it is also possible to provide only a part of the heat radiating portions 210, 220, 230, 240 and 250.

On the other hand, in the electrode 130, a pair of through holes 178A and 178B that spatially connect the gap (heat dissipation space) 160 and the electrode outer surface 130M are formed at symmetrical positions. By forming the through holes 178A and 178B, the inflow and outflow of gas in the discharge space DS increases, and the electrode temperature can be effectively suppressed. Here, a pair of through holes 178A and 178B are used, but the number, the hole diameter, the position, and the hole formation angle with respect to the axial direction X are appropriately determined according to the lamp size, the electrode size, and the like.

The electrodes shown in this embodiment can also be applied to discharge lamps other than short arc type discharge lamps. Since the temperature rise of the electrode can be suppressed, it is suitable for a discharge lamp having a relatively large power of 1 kW or more. Further, although solid phase bonding (SPS, HP, etc.) is preferable as the bonding method, other bonding methods (for example, melt bonding) can also be applied. At the time of joining, an intermediate member may be sandwiched between the front end side member and the rear end side member to bring the joint surfaces into close contact with each other. Examples of the intermediate member include rhenium, tantalum, molybdenum, tungsten, or alloys thereof.

The shape, size, and the like of the columnar portion and the tubular concave portion are arbitrary, and may be, for example, a columnar portion whose diameter changes along the axial direction X, a cylindrical concave portion having a reduced diameter surface on the bottom surface, or the like. Further, it is possible to configure the columnar portion and the cylindrical concave portion with different members. For example, it is possible to form a columnar portion by a member having excellent thermal radiation and being lightweight, and to form a tip side member by a member having excellent heat resistance and thermal conductivity. Further, the columnar portion may be joined to the rear end side member to form a structure. Specifically, tungsten, molybdenum, alloys thereof, ceramics, etc. may be used, an emitter may be contained, and these alloys can be applied and can be appropriately selected.

10 Discharge lamp 30 Electrode (anode)
32 Rear end side member 34 Front end side member 40 Cylindrical recess 50 Columnar part 60 Gap (heat dissipation space)
70 Inclined surface 80 Through hole

Claims (8)

With the discharge tube
It is provided with a pair of electrodes arranged to face each other in the discharge tube.
At least one of the electrodes
Cylindrical recesses along the axial direction facing the opposite direction to the electrode tip surface side,
A columnar portion surrounded by the cylindrical recess and
It is provided with at least a heat dissipation space formed along the axial direction around the side surface of the columnar portion.
A discharge lamp characterized in that a through hole connecting the bottom surface of the tubular recess and the tip surface of the electrode is formed. The heat dissipation space further includes an axial vertical heat dissipation space formed along the vertical direction of the axis between the bottom surface of the tubular recess and the end surface of the columnar portion.
The discharge lamp according to claim 1, wherein the through hole is connected to the heat radiation space in the vertical direction of the axis. The discharge lamp according to claim 1 or 2, wherein the through hole has a spatial region through which an electrode shaft passes. The central axis of the columnar portion and the tubular recess coincides with the electrode axis,
The discharge lamp according to any one of claims 1 to 3, wherein the through hole is formed with the electrode shaft as the central axis. The discharge lamp according to any one of claims 1 to 4, wherein the heat radiating portion is formed on at least one of the end surface and the side surface of the columnar portion. The discharge lamp according to any one of claims 1 to 5, wherein an inclined surface inclined in a direction approaching the electrode tip surface toward the through hole is formed on the bottom surface of the tubular recess. The cylindrical recess is formed in the tip side member having the electrode tip surface, and is formed.
The discharge lamp according to any one of claims 1 to 6, wherein the columnar portion is formed on a rear end side member connected to an electrode support rod. A cylindrical recess is formed around the central axis with respect to the columnar tip-side solid member having the electrode tip surface.
A through hole is formed around the central axis of the cylindrical recess to form a through hole.
For the solid member on the rear end side of the columnar, a columnar portion smaller in size than the tubular recess is formed around the central axis.
The front end side solid member and the rear end side solid member are combined so that the columnar portion is coaxially arranged in the cylindrical recess.
A method for manufacturing an electrode for a discharge lamp, which comprises forming an electrode including the front end side solid member and the rear end side solid member by solid phase bonding.

Images