KR20150056783A - Method for manufacturing discharge lamp electrode - Google Patents

Abstract

A method of manufacturing an electrode for a discharge lamp according to the present invention is a method for manufacturing an electrode for a discharge lamp by solid-state bonding, comprising a columnar tip solid member including at least a part of an electrode tip and containing an emitter, Shaped solid body members having a larger diameter than the joint surface of the tip solid member are solid-phase bonded to each other via the joint surfaces, and the electrode material produced by the solid- Is formed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrode for a discharge lamp,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp used in an exposure apparatus or the like, and more particularly to a method of manufacturing an electrode for a discharge lamp to which a plurality of members are bonded.

In discharge lamps, electrodes are formed by joining members having different kinds of metals, crystal characteristics, etc. according to high output. For example, a metal member containing an emitter such as thorium is bonded to an electrode tip, and a refractory metal member such as pure tungsten is used as a body to join the two metal members together.

As the bonding method, diffusion bonding, which is one of the solid phase bonding, is known. In the diffusion bonding, it is possible to bond the crystal structure in the vicinity of the bonding face so as to be inclined in the axial direction or to prevent the metal crystal grains from being deformed along the axial direction, and deterioration of electrode performance due to bonding can be suppressed 1, 2). Here, discharge plasma sintering bonding (SPS bonding) is performed as a diffusion bonding in accordance with a predetermined pressure, a pressing time, and a bonding temperature.

In electrode molding by such diffusion bonding, the electrode shape is determined by cutting. For example, a cylindrical torn tungsten (thorium tungsten) member constituting a cylindrical tip portion and a cylindrical tungsten member constituting a body portion are prepared. Then, the contact surfaces having the same diameter are abutted against each other, and electric current is applied while applying pressure from both sides of the member. After the diffusion bonding, the front end side of the integrated member is cut into a conical shape to obtain an electrode shape (see Patent Document 3).

In the case of forming electrodes by solid-state bonding of different metal materials, since the thermal expansion rate is also different, a large force is applied to the joint surface during lighting, and the electrode may be broken. In order to prevent this, there is known an electrode in which annular projections are provided on the joint surfaces of the distal end portion and the body portion, and these joint portions are engaged with each other for diffusion bonding (see Patent Document 4).

On the other hand, a method of lengthening the life of the lamp by adjusting the area ratio of the electrode side surface is also known (see Patent Document 5). Wherein a ratio of a side surface area of the thorium tungsten portion to an electrode area is made to fall within a predetermined range in a discharge lamp in which thorium tungsten is used as an electrode tip portion and the main portion of pure tungsten is subjected to diffusion bonding.

Japanese Laid-Open Patent Publication No. 2011-249027 Japanese Laid-Open Patent Publication No. 2011-71091 Japanese Laid-Open Patent Publication No. 2012-15007 Japanese Laid-Open Patent Publication No. 2011-216442 Japanese Laid-Open Patent Publication No. 2011-154927

In the case where the electrode body is made of a metal containing an emitter such as thorium tungsten, the supply of the emitter passes through the junction surface. The configuration of the bonding surfaces such as the size of the bonding surface, the smoothness of the bonding surface, the bonding conditions at the solid-phase bonding, and the bonding surface shape affects the electrode performance such as strength, conductivity, and thermal conductivity of the electrode.

For example, the magnitude of the diameter of the joint surface itself affects the electrode performance. Conventionally, in the case of solid-state bonding, since the influence of the size of the diameter of the bonding surface is not considered, the electrode performance deteriorates in some cases.

The bonding temperature, bonding time, and pressing force also differ depending on the size of the bonding surface diameter. If it is set that there is no correlation between the bonding temperature, the bonding time, the pressure, and the diameter of the bonding surface, desired electrode performance can not be obtained.

Therefore, when electrodes are formed by solid-state bonding of a plurality of members, it is required to set the bonding temperature, the bonding time, the pressure, and the diameter of the bonding surface in relation to each other, and set the value to realize excellent electrode performance.

On the other hand, the cross section of the tungsten tungsten member is lower in smoothness than the cross section of the tungsten member. The difference in smoothness becomes more significant as the diameter increases. As a result, the bonding strength becomes uneven on the bonding surface, and stable bonding strength can not be obtained.

In addition, when the diffusion bonding is performed by energization heating, a current easily flows on the surface side depending on bonding conditions and the like, and the bonding strength near the peripheral portion of the bonding surface is larger than that at the center portion. Therefore, if the tip portion is formed by cutting after the diffusion bonding, the portion near the surface having a large bonding strength is further shaved, and the bonding strength is lowered.

Therefore, it is necessary to bond the member constituting the tip portion containing the emitter such as the tritiated tungsten and the member constituting the body portion to the solid phase bonding without destabilization of the bonding strength.

The structure of the bonding surface also affects the movement of the emitter. The movement of the emitter toward the end face of the tip of the electrode during lamp lighting is based on intergranular diffusion diffusing from the inside of the electrode to the surface and concentration diffusion diffusing along the electrode surface. Since the grain boundary diffusion has no directivity in the moving direction, the distribution of the emitters moving to the electrode surface becomes non-uniform. Further, when the surface of the electrode moves toward the front end surface of the electrode due to the diffusion of the surface concentration after moving to the surface along the circumferential direction of the tip end, it takes time to supply the emitter.

Since the diffusion speed differs depending on the electrode temperature, the supply amount of the emitter moving toward the front end face of the electrode front end is not stable, and the emitter concentration is uneven in the vicinity of the front end of the electrode. As a result, the luminous point of the arc discharge is liable to move to a place where the concentration of the emitter is high, and the illumination becomes blinking and unstable.

Therefore, it is necessary to uniformly and stably supply the emitter efficiently to the front end face side of the electrode front end portion to uniformize the emitter concentration at the front end portion of the electrode.

A method of manufacturing an electrode for a discharge lamp according to the present invention is a method for manufacturing an electrode for a discharge lamp, which comprises at least a part of an electrode tip end, a columnar tip solid member containing an emitter and at least an electrode body part, Shaped solid body members having a surface in the form of a solid phase are bonded to each other through bonding surfaces of the respective members and cutting is performed so as to form a tapered electrode tip portion with respect to the electrode material produced by solid state bonding.

For example, a cathode is manufactured as an electrode and used for a discharge lamp. Toroidal tungsten or the like is applicable as the emitter, and the shapes of the tip solid member and the solid body member are arbitrary, and a metal material, a ceramic material, or the like is applicable as the material. As the solid-state bonding method, various diffusion bonding can be applied, and in particular, it is possible to solid-state bonding by SPS bonding.

In the present invention, the diameter of the distal end solid member is smaller than the diameter of the distal end solid member. By performing the cutting process after the solid-state bonding, it is possible to constitute the electrode in which only the end of the bonding surface with which the wedge portion is easily formed and the bonding strength is weak is efficiently removed.

For example, at the cutting step, it is possible to cut at least the peripheral edge portion of the joint surface of the tip solid member and the body solid member in the electrode material. Particularly, in the electrode material, the cutting can be performed so as to remove the wedge portion formed at the peripheral edge portion of the joint surface of the tip solid member. In addition, in the electrode material, it is also possible to perform a cutting process so as to leave only the center portion of the joint surface of the tip solid member.

In order to enable such cutting, the ratio of the diameter of the joint surface of the tip solid member to the diameter of the joint surface of the solid body may satisfy 0.05 <D1 / D2 <1.

On the other hand, a method of manufacturing an electrode for a discharge lamp according to another aspect of the present invention is a method of manufacturing an electrode for a discharge lamp, which includes a stepped portion having a convex portion or a concave portion (hereinafter referred to as a convex portion / concave portion) A manufacturing method of forming a body portion having a concave / convex portion to be fitted and causing the front end portion and the body portion to abut against each other to perform the SPS bonding, characterized in that the distal end portion and the body portion are partially solid-phase bonded in the SPS bonding.

In order to perform partial solid-state bonding, for example, at least one of the bonding time, the sintering / bonding temperature, and the applied voltage, which is set when the electrode front end and the opposite face of the body part are solid- As a result, a solid-state junction is formed in part, and at least convex portions in which opposing surfaces are formed, and portions in which the solid-state junctions are not formed in the concave portions are formed in addition to the surfaces along the vertical direction of the electrode axis.

The discharge lamp manufactured by such a manufacturing method has an emitter, an electrode tip portion having a convex portion or a concave portion, and a body portion having a concave portion or a convex portion fitted to the convex portion or concave portion of the electrode tip portion. The tip of the electrode has a front end face that is a bright spot of the arc discharge, and constitutes at least a part of the electrode diameter reduction portion such as a conical shape. The trunk portion may have, for example, a columnar shape, or a part thereof may constitute the electrode tip portion.

The tip of the electrode can be made of, for example, tritiated tungsten, and the body part can be made of pure tungsten or the like. The convex portion and the concave portion may be formed at arbitrary positions, and concave portions and convex portions may be formed along the electrode axis direction, and faces facing each other along a direction other than the direction perpendicular to the electrode axis may be formed.

It is also possible that the convex portion and the concave portion are formed so as to be fitted to each other, and a set of concave portion, convex portion or plural concave portions and convex portions can be provided. However, the fitting here indicates that the shapes thereof are matched with each other, and that the opposite faces are substantially in contact with each other (when viewed at a macro level, not at a molecular level). For example, the shape of the convex portion / concave portion can be formed into a columnar shape such as a columnar shape, a triangular column, or a square column.

In the present invention, the electrode tip portion and the body portion are partially solid-phase bonded. The electrode front end portion and the body portion are not solid-phase bonded at least on part of the surfaces of the opposing surfaces of the convex portion / concave portion of the electrode tip end portion and the concave / convex portion of the body portion among the plurality of opposing surfaces.

There is a portion which is not solid-state bonded in the convex portion and the concave portion. Therefore, in the non-solid phase junction portion of the thorium component moving due to grain boundary diffusion during lamp lighting, movement in the direction perpendicular to the electrode axis Is limited. As a result, much of the thorium component moving along the vertical direction of the electrode axis does not reach the surface of the electrode, but rather moves toward the tip end surface of the tip of the electrode much earlier.

The formation positions of the convex portion and the concave portion are arbitrary. For example, it is possible to form convex / concave portions of the electrode tip portion and concave / convex portions of the body portion coaxially with respect to the electrode axis. In this case, it is possible to intensively move the thorium component dispersed throughout the tip of the electrode toward the tip end surface of the tip of the electrode.

It is possible to increase the strength of the concave portion and the convex portion by solid-state bonding with respect to the other opposing surfaces without solid-state bonding in consideration of the supply of the thorium component. That is, it is possible to constitute the solid-state junction on the surface of the electrode front end portion and the body portion other than the convex portion / concave portion of the electrode tip portion and the concave portion / convex portion of the body portion and facing each other along the direction perpendicular to the electrode axis.

A method of manufacturing an electrode for a discharge lamp according to another aspect of the present invention is a method of manufacturing an electrode for a discharge lamp including a plurality of solid bodies including at least one solid solid member having a distal end and a rear solid member supported by the electrode support, Wherein when the outer diameter L (mm) of the bonding surface is in the range of 2? L? 60, the plurality of solid members are solid-phase bonded between the solid- And solid-phase bonding is performed so as to satisfy the following conditional expression.

3000? Tt + P? 150093

(1200? T? 2500, 10? P? 90, 3?

Where L is the bonding surface outer diameter (mm), T is the bonding temperature (占 폚), P is the pressing force (MPa) applied at the bonding and t is the bonding time (min) holding the metal member under pressure.

Alternatively, the method for manufacturing an electrode for a discharge lamp according to another aspect of the present invention is solid-state bonding so as to satisfy the following conditional expression.

370.4 / L? (T + P) t / 9.8L? 15857.1 / L

2? L? 60, 1200? T? 2500, 10? P? 90, 3?

The above two equations set the setting range of the variables L, T, P, and t capable of sufficiently maintaining the bonding strength, empirically derived, and the variables are set to have correlation with each other.

When examining each variable individually, it is preferable that the joining surface outer diameter L, the joining temperature T, the pressing force P, and the joining time t satisfy the following conditions.

L? 30, 1500? T? 2200, 30? P? 80, 5?

At least one of the plurality of solid members may be a metal member. Further, before the bonding, the front-end side solid member and the rear-end side solid member to be joined to the front-end side solid member may be formed and molded. A metal member containing thorium may be prepared as the tip side solid member. Further, it is possible to apply the SPS junction as the solid state bonding method.

According to the present invention, it is possible to produce an electrode having excellent electrode performance based on solid phase bonding.

Fig. 1 is a plan view schematically showing a short arc type discharge lamp according to the first embodiment. Fig.
2 is a schematic cross-sectional view of the anode.
3 is a view showing a discharge plasma sintering apparatus.
Fig. 4 is a graph showing a graph of the conditional expression (1).
5 is a graph showing the graph of the conditional expression (2).
6 is a schematic cross-sectional view of a cathode according to a second embodiment.
7 is a view showing a manufacturing process of a negative electrode.
8 is a schematic cross-sectional view of a cathode according to a third embodiment.
Fig. 9 is a schematic plan view of the front end portion and the trunk portion before joining. Fig.
10 is a schematic plan view of a cathode.
11 is a schematic plan view of a cathode in the fourth embodiment.
12 is a graph showing the coordinate positions of the examples and comparative examples shown in Table 1 and the graphs showing the regions of the conditional expression (1).
Fig. 13 is a graph showing a coordinate position of each embodiment and a comparative example and a graph showing an area of conditional expression (2). Fig.
14 is an enlarged view of a portion of FIG.

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

Fig. 1 is a plan view schematically showing a short arc type discharge lamp according to the first embodiment. Fig.

The short arc type discharge lamp 10 is a discharge lamp which can be used for a light source of an exposure apparatus (not shown) for pattern formation and has a discharge tube (light emitting tube) 12 made of transparent quartz glass. In the discharge tube 12, the cathode 20 and the anode 30 are disposed opposite to each other with a predetermined gap therebetween.

Sealing tubes 13A and 13B made of quartz glass are provided integrally with the discharge tube 12 so as to oppose to both sides of the discharge tube 12 and both ends of the sealing tubes 13A and 13B are connected to a mouth 19A and 19B ). The discharge lamp 10 is disposed along the vertical direction so that the anode 30 is on the upper side and the cathode 20 is on the lower side. As will be described later, the anode 30 is composed of two metal members 40 and 50.

Electrode support rods 17A and 17B are provided on the inside of the sealing tubes 13A and 13B to support the metallic cathode 20 and the anode 30 and a metal ring Are respectively connected to the conductive lead rods 15A and 15B through the lead wires 16A and 16B. The sealing tubes 13A and 13B are fused with a glass tube (not shown) provided in the sealing tubes 13A and 13B, whereby the discharge space DS sealed with mercury and rare gas is sealed.

The lead rods 15A and 15B are connected to an external power supply unit (not shown) and are connected to the negative electrode 20, the lead electrodes 15A and 15B, the metal foils 16A and 16B, and the electrode support rods 17A and 17B, And a voltage is applied between the anode 30. When electric power is supplied to the discharge lamp 10, an arc discharge occurs between the electrodes and a bright line (ultraviolet light) by mercury is emitted.

2 is a schematic cross-sectional view of the anode.

The anode 30 is an electrode structure in which the metal members 40 and 50 are bonded to each other. The metal member 40 has a truncated cone portion 40A including an electrode tip end face 40S, a cylindrical metal member 50, And a cylindrical portion 40B having the same diameter as that of the metal member 50 and joined to the metal member 50. The metal member 40 is made of a high melting point such as pure tungsten or an alloy containing tungsten as a main component.

On the other hand, the cylindrical metal member 50 is made of a metal having a higher thermal conductivity than the metal member 40 (for example, tungsten, thorium, molybdenum, tantalum having a getter effect, And the like).

The metal members 40 and 50 are diffusion bonded according to a discharge plasma sintering (SPS) method. Therefore, a diffusion layer is formed in the vicinity of the joint surface S formed along the direction perpendicular to the electrode axis X.

Here, only the bonding surface crystal grains contributing to bonding are partially deformed, and the other crystal grains in the vicinity of the bonding surface S deform along the direction perpendicular to the bonding surface (electrode axis direction), and the grain size by secondary recrystallization And there is almost no migration of grain boundaries. In addition, the crystal grain size along the bonding surface is substantially uniform, and the crystal grain size along the electrode axis in the vicinity of the bonding surface is also substantially uniform.

By forming the diffusion layer sandwiching the bonding surface S, the thermal conductivity and the conductivity do not vary along the bonding surface S. While the heat is transferred from the electrode tip end face 40S (1000 deg. C or higher) which becomes high by the lamp lighting to the electrode support rod 17B, the temperature distribution inside the anode is distributed symmetrically with respect to the electrode axis X And the heat transfer is not affected by the bonding surface S.

It is also possible to perform the diffusion bonding so that the diameter of the metal crystal becomes substantially uniform along the bonding surface S and the crystal structure is inclined along the electrode axis X. [ By the inclination, the crystal diameter changes continuously or stepwise along the electrode axis X. [

The shapes of the metal members 40 and 50 may be other than those shown in Fig. 2, or the metal members 40 and 50 may be solid-phase bonded with another metal member interposed therebetween.

3 is a view showing a discharge plasma sintering apparatus.

The discharge plasma sintering method is a sintering method in which pulsed electric energy is directly injected into the grain gap of the green compact or the molded body and the high temperature energy of the discharge plasma generated instantaneously by the spark discharge phenomenon is applied by thermal diffusion and electric field diffusion.

The discharge plasma sintering apparatus 60 of Fig. 3 has a vacuum chamber 65 and is provided between the upper punch 80A, the lower punch 80B and the graphite die 80 provided inside the vacuum chamber 65, The metal members 40 and 50 having the shape shown in Fig. 2 are provided in a state in which their contact surfaces are in contact with each other. The metal members 40 and 50 are formed so that their contact surfaces have the same size by a metal working process such as cutting.

The upper punch 80A and the lower punch 80B made of graphite are connected to the upper punch electrode 70A and the lower punch electrode 70B, respectively. After setting the inside of the apparatus to a vacuum atmosphere, a voltage is applied between the upper punch 80A and the lower punch 80B by the pulse power source 90. [

Then, a pressure is applied between the upper punch 80A and the lower punch 80B by a pressurizing mechanism (not shown) along with energization. The temperature is raised instantaneously to a predetermined temperature by a discharge plasma by energization, and then maintained for a predetermined time in a state where the pressure is applied. As a result, a positive electrode having the shape shown in Fig. 2 is obtained.

Next, referring to Figs. 4 and 5, bonding conditions at the time of producing an electrode will be described.

As described above, when the metal members 40 and 50 are subjected to SPS bonding, the bonding temperature, the pressing force, and the bonding / holding time are determined. Setting of these parameters greatly influences the electrode performance. In addition, these parameters have a correlation with the diameter of the bonding surface, and it is necessary to set the outer diameter of the bonding surface, the bonding temperature, the pressing force, and the bonding time to appropriate values in order to obtain the optimum condition.

In the present embodiment, an appropriate value of each parameter is obtained and an equation showing the correlation between the parameters is derived. By providing the parameters so as to satisfy the derived conditional expression, it becomes possible to automatically obtain an electrode structure having an excellent electrode performance to some extent without setting each parameter heuristically.

First, the outer diameter L (mm) of the joint surface is set to satisfy 2? L? 60. When the outer diameter L of the bonding surface is less than 2 mm, the pressing at the time of bonding can not be increased, and micro discharge is partially generated outside the bonding surface, so that the bonding is not stabilized. If the pressing force at the time of bonding is increased, the metal material before bonding tends to be cracked or deformed. Also, the diffusion of thorium occurs, and the thorium content decreases, and the lamp performance deteriorates. On the other hand, if the outer diameter L of the bonding surface is larger than 60 mm, the processing for obtaining the smoothness of the bonding surface becomes complicated and the amount of thorium used becomes excessive.

The bonding temperature T (占 폚) at the time of bonding is set so as to satisfy 1200? T? 2500. If the junction temperature T is higher than 2500 ° C, it exceeds the melting point of thorium (about 1800 ° C) and some of the thorium contained in the uppermost layer near the bonding surface melts and evaporates. When thorium is diffused on the bonding surface, the bonding strength is lowered. On the other hand, when the bonding temperature T is lower than 1200 占 폚, sufficient bonding strength can not be obtained.

And the pressing force P (MPa) at the time of bonding is set to satisfy 10? P? 90. If the pressing force P is higher than 90 MPa, cracking or deformation of the metal member tends to occur at the time of bonding. In addition, although it is necessary to press the two metal members face-to-face and coaxially pressurize, there is a deviation in the direction of the pressurization, and warping or depression occurs in the bonding surface, and density in the vicinity of the bonding surface becomes uneven. On the other hand, when the pressing force P is less than 10 MPa, sufficient bonding strength can not be obtained.

The bonding time t (min), which is the metal member holding time at the time of bonding, is set to satisfy 3? T? 60. If the holding time t is longer than 60 min, the productivity is lowered. On the other hand, if the holding time t is less than 3 min, sufficient bonding strength can not be obtained.

As described above, numerical ranges for realizing excellent electrode performance are determined for the outer diameter L of the bonding surface, the temperature T, the pressing force P, and the bonding time t at the time of SPS bonding. However, there is a correlation between these parameters, and it is difficult to determine a combination of parameters that realize better electrode performance while changing each parameter separately.

Thus, in this embodiment, two conditional expressions are defined. By graphing the numerical ranges that satisfy the conditional expression, the range of the four parameters is visualized.

First, one conditional equation considering energy at the time of bonding is defined as follows.

3000? Tt + P? 150093 ... (One)

(2? L? 60)

The joining temperature T, the pressing force P, and the joining time t are determined so as to satisfy the formula (1) while changing the joining face outer diameter L, so as to satisfy the lower limit value and the upper limit value.

Fig. 4 is a graph showing a graph of the conditional expression (1). As shown in Fig. 4, the range satisfying the expression (1) is graphed as the area S1 by defining the two-dimensional coordinate system of the horizontal axis L and the vertical axis Tt + P. The bonding strength varies depending on the (L, Tt + P) coordinate position in the rectangular area S.

In addition, the following conditional expression considering the bonding strength is defined.

370.4 / L?? / L? 15857.1 / L ... (2)

(? = (T + P) t / 9.8, 2? L? 60)

5 is a graph showing the graph of the conditional expression (2). As shown in Fig. 5, the range satisfying the expression (2) is graphed as the area S2 by defining the two-dimensional coordinate system of the horizontal axis L and the vertical axis (T + P) t / (9.8L).

By making the settable ranges of the respective parameters as described above, it is possible to easily estimate and set numerical values that achieve equivalent thermal conductivity and strength, even when an electrode having different electrode structures, that is, electrodes having different bonding surface diameters are manufactured.

Particularly, it is possible to manufacture an electrode having better electrode performance by determining the bonding surface outer diameter L, the bonding temperature T, the pressing force P, and the bonding time t in the following ranges.

5? L? 30, 1500? T? 2200, 30? P? 80, 5? (3)

As described above, according to the present embodiment, the metal member 40 including a component such as thorium and the metal member 50 such as pure tungsten metal are SPS-bonded to form a positive electrode. Then, at the time of SPS bonding, the bonding surface outer diameter L, the bonding temperature T, the pressing force P, and the bonding time t are set to the above-mentioned allowable range and the above-mentioned equations (1) and (2) are satisfied.

The electrode may be manufactured by a diffusion bonding method other than the SPS bonding. For example, the electrode can be manufactured by a diffusion bonding method in which hot pressing (HP), hot isostatic pressing (HIP), or the like is performed while pressing. Further, a solid-phase bonding method other than the diffusion bonding method (friction welding method, ultrasonic bonding method, etc.) is also applicable.

Further, different metal members may be solid-phase bonded to the negative electrode. Alternatively, one side may be a metal member and the other side may be a solid-phase bonding by using a member (ceramic or the like) made of another material. Alternatively, the insert member may be interposed between the members.

Next, a discharge lamp according to a second embodiment will be described with reference to Figs. 6 and 7. Fig. In the second embodiment, the electrodes are formed by solid-phase bonding members having different diameters.

6 is a schematic cross-sectional view of a cathode according to a second embodiment.

The cathode 120 employs an electrode structure formed by joining two metal members 1110 and 1120, and then forming by cutting. The metal member 1110 constitutes a part of the tip end portion 120A and the metal member 1120 constitutes a columnar body portion 120B and constitutes the body side portion of the tip end portion 120A.

The metal member 1110 is a metal member made of tungsten which is tungsten containing thoria (ThO2), and the metal member 1120 is made of a metal having a higher thermal conductivity than the metal member 1110 (here, pure tungsten) .

The metal members 1110 and 1120 are subjected to diffusion bonding according to Spark Plasma Sintering (SPS). Therefore, a diffusion layer is formed in the vicinity of the joint surface S perpendicular to the electrode axis E. The diameter of the metal crystal is substantially uniform along the bonding surface S. With regard to the electrode axis E, the crystal diameter except for the vicinity of the bonding surface S is substantially uniform. With the formation of the diffusion layer sandwiching the bonding surface S, the thermal conductivity and the conductivity are not uniform along the bonding surface S.

7 is a view showing a manufacturing process of a negative electrode. With reference to Fig. 7, SPS bonding and cutting processing will be described. It is also possible to manufacture the positive electrode in the same manner.

First, cylindrical metal members 1110 and 1120 are formed. At this time, the diameter D1 of the metal member 1110 is formed to be smaller than the diameter D2 of the metal member 1120. [ Here, the diameters D1 and D2 are determined so that 0.05 <D1 / D2 <1 when 3 <D1 <30 and 5 <D2 <60 (all in mm). The upper limit value is set so as to delete at least the wedge portion described later. The lower limit value is determined according to the inclination angle of the tip of the electrode, the bonding condition, and the like.

The prepared metal members 1110 and 1120 are subjected to an SPS bonding process in the same manner as in the first embodiment. Thus, the electrode material 1200 is obtained.

Then, the generated electrode material 1200 is subjected to cutting. Here, each of the metal members 1110 and 1120 is partially cut so as to form a conical electrode line section indicated by a broken line (K). The metal member 1110 carries out the portion other than the central portion 1110T of the bonding surface 1110S and the metal member 1120 carries out the cutting of the peripheral portion of the bonding surface 1120S. The cutting method, the cutting mechanism, and the like are performed by a known method, a mechanism, and the like.

The position of the cut surface indicated by the broken line K, that is, the position where the electrode outer circumferential surface is formed, depends on the size and the difference of the diameters D1 and D2 of the metal member 1110 and the metal member 1120, The thickness of the base 1110, and the like. In particular, it is determined that at least the peripheral edge portion 1110T of the bonding surface of the metal member 1110 is removed, leaving the bonding surface central portion 1110C.

The electrode material 1200 after cutting has a conical metal member 1110 and a metal member 1120 partly in the form of a truncated cone and the other part in the shape of a cylinder. The electrode tip part 120A, the body part 120B are formed.

As described above, according to the present embodiment, the discharge lamp cathode 120 having the electrode tip portion 120A made of tungsten tungsten is bonded by SPS bonding. In the process of SPS bonding, a cylindrical metal member 1110 made of tungsten tungsten and a cylindrical metal member 1120 having a diameter D2 larger than the diameter D1 of pure tungsten and the metal member 1110 are bonded Heated by electrification through the surfaces 1110S and 1120S, and subjected to SPS bonding. Thereafter, cutting is performed so that the cross section indicated by the broken line K becomes the outer peripheral surface of the electrode.

The bonding surface 1110S of the metal member 1110 including the thorium component is lower in smoothness than the bonding surface 1120S of the metal member 1120 of pure tungsten. The larger the diameter of the car becomes, the more remarkable it becomes. However, since the diameter D1 of the bonding surface 1110A, which is smaller than the diameter D2 of the bonding surface 1120, is relatively small, the influence thereof is less likely to appear after the solid-phase bonding, and the lowering of the bonding strength can be suppressed.

In addition, due to the difference in physical properties from the metal members 1110 and 1120, a minute wedge part which is not partially bonded near the end of the bonding surface occurs along the electrode axis vertical direction. In the present embodiment, the cutting edge peripheral portion 1110T of the metal member 1110 is cut so that the wedge formed at the bonding surface peripheral edge portion 1110T at the time of SPS bonding can be removed. As a result, deterioration of the bonding strength can be suppressed.

Particularly, the diameter D1 of the metal member 1110 can be made closer to the diameter D2 of the metal member 1120 by making the cutting portion of the metal member 1110 as small as possible to remove only the wedge portion. This makes it possible to increase the pressing force at the time of SPS bonding, thereby increasing the bonding strength.

On the other hand, when energized at the SPS bonding, the bonding strength at the central portion of the bonding surface may become smaller than the bonding strength near the outer peripheral surface of the metal members 1110 and 1120 due to bonding conditions or the like. However, since the diameter D1 of the metal member 1110 is relatively small, the influence is small. In addition, the range of cutting near the outer periphery of the metal member 1110 having a high bonding strength is relatively small. Therefore, compared with the case where the contact surfaces having the same diameter are abutted with each other, the bonding strength at the center portion is increased.

In the metal member 1110 made of tritiated tungsten, there may be a portion where there is no thorium dioxide in the vicinity of the surface. However, since the surface layer portion of the metal member 1110 is removed by the cutting process after the SPS bonding, destabilization of the arc discharge due to the thorium dioxide defect can be prevented. Further, by performing the cutting process after the SPS bonding, there is no step in the radial direction of the bonding surface. As a result, an abnormal discharge does not occur when the lamp is turned on.

The size of the diameter of the metal member, the inclination angle of the end face of the electrode tip, and the cross-sectional shape of the end face can be arbitrary, and it is possible to cut the end face of the electrode so as to have a flat outer peripheral face without a step to form the tip end of the tapered electrode. The solid member may be made of any material and shape of the metal member, the emitter other than thorium may be contained in the tip of the electrode, or the body may be made of a material other than metal (ceramic, carbon, etc.) Do. Further, the tip of the electrode may be configured to include both the emitter-containing member such as tungsten tungsten and the solid member of the body portion.

Next, a discharge lamp according to a third embodiment will be described with reference to Figs. 8 to 10. Fig. In the third embodiment, a step is provided on the joint surface, and the joint is partially solid-phase bonded.

8 is a schematic cross-sectional view of a cathode according to a third embodiment. Fig. 9 is a schematic plan view of the front end portion and the trunk portion before joining. Fig. Hereinafter, the structure of the cathode will be described.

The cathode 220 has a structure in which a truncated distal end portion 220A having an electrode tip end surface 220S and a columnar trunk portion 220B are joined. The distal end portion 220A is a metal made of tori-tungsten containing a thorium component as an emitter, and the trunk portion 220B is made of a metal having a high thermal conductivity (here, pure tungsten) or an alloy containing the metal.

The distal end portion 220A is provided with a convex portion 223 which protrudes toward the body portion side in the central portion thereof coaxially with the electrode axis E. The body portion 220B is provided with a concave portion 223 (226). The tip portion 220A and the trunk portion 220B are solid-phase bonded to form the cathode 220. [ Here, SPS junction, one of the diffusion junctions, is used.

As shown in Fig. 9, the distal end portion 220A and the trunk portion 220B are composed of a plurality of sections and have connection surfaces 222 and 225 facing each other. End surfaces 222A and 222E perpendicular to the electrode axis E and end surfaces 222C and 222C and 222D parallel to the electrode axis E are formed on the tip 220A side . On the side of the trunk section 220B, cross sections 225A to 225E which are respectively opposite to the end surfaces 222A to 222E of the tip section 220A are formed.

The convex portion 223 of the tip end portion 220A and the concave portion 226 of the body portion 220B are fitted while making contact with each other and a punch (not shown) is attached to each of the opposite surfaces I will. The convex portion 223 of the front end portion 220A and the concave portion 226 of the body portion 220B are fitted to each other in a state of being in contact with each other without any gap in the end faces 222B to 222D and 225B to 225D, .

In the manufacturing process of the discharge lamp electrode, the SPS bonding is performed in the same manner as in the first embodiment. The convex portion 223 of the tip end portion 220A and the concave portion 226 of the body portion 220B of the tip end portion 220A are arranged at the end faces 222B to 222D by adjusting the applied voltage, the pressing force, the bonding temperature and the pressing time (holding time) 222E and 222E and the annular cross sections 225A and 225E are solid-phase bonded without performing solid phase bonding (diffusion bonding) between the annular sections 222A and 222D and 225B to 225D.

For example, when the diameter M (mm) of the cathode 220 is 5? M? 30, the applied voltage V, the pressing force P (Mpa), the sintering temperature T (占 폚) and the bonding time t ? P? 30, 1500? T? 2200, and 5? T? 30, and SPS bonding is performed to obtain the above-described partially solid-bonded cathode 220.

10 is a schematic plan view of the cathode 220. Fig. With reference to Fig. 10, the movement of the thorium component during lamp lighting will be described.

When the lamp is turned on, the thorium component (specifically, thorium dioxide) in the thorium tip portion 220A moves to the surface by grain boundary diffusion. The inside of the convex portion 223 or the end face 222D of the convex portion 223 and the concave portion 226 of the body 220B are merely in contact with each other because the components do not move beyond the cross section of each other , And moves along the surface.

Since the convex portion 223 and the concave portion 226 are in contact with each other without solid-phase bonding, most of the thorium component moves toward the electrode front end face 220S. That is, the thorium component is prevented from moving along the direction perpendicular to the electrode axis E, so that the thorium component moves toward the electrode tip end face 220S rather than toward the surface (conical surface) along the circumferential direction of the tip end portion 220A Movement becomes dominant.

As a result, the internal thorium component reaches the electrode front end face 220S quickly and also at a relatively short total distance. Particularly, since the convex portion and the concave portion are provided at the central portion, the scattered thorium component in the tip portion 220A is supplied to the distal end face 220S with good balance, and the thorium concentration in the vicinity of the distal end face 220S becomes The influence of the time lapse is reduced and stabilized.

In addition, since the thorium component can be stored more in the convex portion 223 than in the tip shape in which the convex portion 223 is not provided, even if the temperature of the tip portion increases due to the lighting condition, The thorium component can be supplied from the portion 223 to the distal end side in a sequential manner.

As described above, according to the present embodiment, the cathode 220 of the discharge lamp is composed of the tip portion 220A made of tungsten tungsten and the body portion 220B made of pure tungsten. The convex portion 223 of the front end portion 220A and the concave portion 226 of the body portion 220B are fitted and SPS bonding is performed. At this time, the convex portion 223 and the concave portion 226 are not bonded to each other in a solid state, but solid-phase bonded at the other end faces 222A, 225A, and 222E and 225E.

The convex portion 223 and the concave portion 226 are brought into close contact with each other as much as possible without gap and also when the distal end portion 220A and the body portion 220B are formed, the cross section is made smooth. However, the cross-section of the convex portion 223 and the concave portion 226 may not be strictly smoothed, or may have a surface roughness such that a small clearance is partially formed. The convex portion 223 and the concave portion 226 may be partly solid-phase bonded, or at least a part of the cross-section or a part of any cross-section may not be solid-state bonded.

Next, a discharge lamp according to a fourth embodiment will be described with reference to Fig. In the fourth embodiment, the concavo-convex shape is reversed. Other configurations are the same as those of the third embodiment.

11 is a schematic plan view of a cathode of a discharge lamp in the fourth embodiment.

The cathode 2120 is composed of a tip portion 2120A and a body portion 2120B. The tip portion 2120A has a concave portion 2123 and the body portion 2120B has a convex portion 2126. [ The end surfaces 2122A and 2125A and the end surfaces 2122E and 2125E are solidly bonded to each other at the distal end portion 2120A and the body portion 2120B while the concave portion 2123 and the convex portion 2126 are not solid- , And they are in contact with each other.

With this configuration, when the lamp is turned on, the thorium component in the distal end portion 2120A moves in the direction of the distal end surface 2120S when it moves to the surfaces 2122B and 2122D of the concave portion 2123. Thereby, the thorium component is efficiently supplied to the distal end face 2120S.

Further, since the distal end portion 2120A has the recess portion 2123, the heat is likely to be transmitted to the distal end face 2120S. Therefore, even in the lighting condition in which the temperature of the tip end portion 2120A is low, the thorium component can be stably supplied.

Hereinafter, an embodiment of the present invention will be described. Here, in order to examine the conditional expressions (1) and (2), a positive electrode which is a plurality of examples and a comparative example was manufactured and tested.

(Example)

The discharge lamp of the first embodiment corresponds to the discharge lamp of the first embodiment. Regarding the condition (1), a positive electrode having a thorium tungsten (tungsten tungsten) member at the tip end and a net tungsten member at the end of the body was manufactured by SPS bonding. At this time, Examples 1 to 3 and Comparative Examples 1 to 3 were produced by changing the bonding surface outer diameter L, the bonding temperature T, the pressing force P, and the bonding time t, respectively. Thereafter, a tensile test was performed on each of the produced positive electrodes. The experimental results are shown in Table 1.

Example 1 and Comparative Example 1 are electrodes manufactured by SPS bonding a thorium tungsten member and a pure tungsten member without an insert member. Example 2 and Comparative Example 2 are electrodes which are SPS-bonded with a tantalum (Ta) member interposed therebetween as an insert member. Example 3 and Comparative Example 3 are electrodes which are SPS-bonded with a rhenium (Re) member interposed therebetween as an insert member.

For the tensile test, both ends of the electrode were held with a holding tool of a material testing machine, and the force at the time of breaking was measured by pulling at a speed of 10 mm / min.

12 is a graph showing the coordinate positions of the examples and comparative examples shown in Table 1 and the graphs showing the regions of the conditional expression (1).

As shown in Fig. 12, Examples 1 to 3 are included in the region S1, and as can be seen from Table 1, the tensile strength is very strong. On the other hand, Comparative Examples 1 to 3 do not belong to the region S1 and the tensile strength is weak. Since the bonding energy was excessive, the electrode was deformed in the tensile test. Thorium diffusion was also observed.

Thus, by determining the bonding surface outer diameter L, the bonding temperature T, the pressing force P, and the bonding time t within the range of the area S1, excellent electrode performance can be obtained.

Next, regarding the condition (2), an electrode in which a tip portion is a thorium tungsten member and a body portion is a net tungsten member is manufactured by SPS bonding. Examples 5 to 8, 11 to 15, and Comparative Examples 1 to 4, and 9 to 10 were produced while changing the joining face outer diameter L, the joining temperature T, the pressing force P, and the joining time t. Thereafter, a tensile test was conducted on the produced positive electrode. The experimental results are shown in Table 2. However, different from Table 1, the numbers of Examples and Comparative Examples are assigned in the order of manufacture and test.

Fig. 13 is a graph showing a coordinate position of each embodiment and a comparative example and a graph showing an area of conditional expression (2). Fig. 14 is an enlarged view of a portion of FIG.

13 and 14, the comparative example is located outside the range of the area S2. As shown in Fig. As can be seen from Table 2, in Comparative Examples, thorium diffusion, insufficient bonding strength, or electrode deformation were observed. On the other hand, in all the examples, the bonding strength was high and excellent electrode performance was obtained.

In the above embodiment, the thorium tungsten tip portion and the tungsten body portion are joined to each other. However, similar results can be obtained in the SPS joint between the other solid metal members.

With regard to the present invention, various changes, substitutions and substitutions are possible without departing from the spirit and scope of the invention as defined by the appended claims. Further, the present invention is not intended to be limited to the processes, apparatuses, manufacture, compositions, means, methods and steps of the specific embodiments described in the specification. Those skilled in the art will recognize that devices, means and methods substantially resulting in functions substantially equivalent to those resulting from the embodiments described herein from the disclosure of the present invention, or substantially resulting in equivalent actions and effects are derived. Accordingly, the appended claims are intended to be encompassed within the scope of such apparatus, means, and methods.

The present application is based on a Japanese patent application (application No. 2012-208372, filed on September 21, 2012, application No. 2012-212807, filed on September 26, 2012, application No. 2012-214630, application filed on September 27, 2012) The disclosure of which is incorporated herein by reference in its entirety, including the specification, drawings and claims of the basic application.

10 ... Discharge lamp 12 ... discharge pipe
30 ... The anode 40 ... The metal member (front-end-side solid member)
50 ... Metal member (rear end side solid member) S ... Abutment surface

Claims (10)

A columnar tip solid member constituting at least a part of an electrode tip portion and containing an emitter,
A solid body of a columnar body having at least a joint surface having a larger diameter than the joint surface of the tip solid member is solid-phase bonded via mutual joining surfaces,
Wherein cutting processing is performed so as to form a tapered electrode tip portion for an electrode material produced by solid-state bonding. The method of manufacturing an electrode for a discharge lamp according to claim 1, wherein in the electrode material, at least a peripheral edge portion of the joint surface of the tip solid member and the body solid member is cut. The method for manufacturing an electrode for a discharge lamp according to claim 2, wherein the tip-side solid member is a metal member containing thorium. A tip end portion having a convex portion / concave portion and a body portion having a concave / convex portion fitted to the convex portion / concave portion of the tip portion,
Wherein the SPS bonding is carried out by abutting the distal end portion and the moving body portion,
Wherein the tip portion and the body portion are partly solid-state bonded in SPS bonding. 5. The plasma display panel according to claim 4, wherein in the SPS bonding, the surfaces of the electrodes facing each other along the direction perpendicular to the electrode axis other than the convex portion / concave portion of the electrode tip portion and the concave portion / convex portion of the body portion are solid-
Wherein at least a part of the surfaces of the convex portion / concave portion of the electrode tip portion and the mutually facing surfaces of the concave portion / convex portion of the body portion is not solid-state bonded. A plurality of solid members including a tip side solid member having an electrode tip end and a rear end side solid member supported by the electrode support bar, at least one of which is a metal member,
And solid-phase bonding the plurality of solid members between the front-end solid member and the rear-end solid member,
When the bonding surface outer diameter L (mm) is in the range of 2? L? 60, solid state bonding is performed so as to satisfy the following conditional expression
3000? Tt + P? 150093
1200? T? 2500, 10? P? 90, 3?
Where P is the pressing force (MPa) applied at the time of bonding, and t is the bonding time (min) holding the metal member in a pressurized state. Wherein the electrode for discharge lamp is manufactured by the method. A plurality of solid members including a tip side solid member having an electrode tip end and a rear end side solid member supported by the electrode support bar, at least one of which is a metal member,
And solid-phase bonding the plurality of solid members between the front-end solid member and the rear-end solid member,
Solid-phase bonding so as to satisfy the following conditional expression
370.4 / L? (T + P) t / 9.8L? 15857.1 / L
2? L? 60, 1200? T? 2500, 10? P? 90, 3?
Where P is the pressing force (MPa) applied at the time of bonding, and t is the bonding time (min) holding the metal member in a pressurized state. Wherein the electrode for discharge lamp is manufactured by the method. 8. The method according to any one of claims 6 to 7, wherein the bonding surface outer diameter L, the bonding temperature T, the pressing force P, and the bonding time t satisfy the following conditions
L? 30, 1500? T? 2200, 30? P? 80, 5?
Of the total thickness of the discharge lamp. The method according to any one of claims 6 to 7, wherein at least one of the plurality of solid members is a metal member, and the front end side solid member and the rear end side solid member joined to the front end side solid member And forming an electrode for a discharge lamp. A discharge lamp comprising an electrode for a discharge lamp manufactured by the method for manufacturing an electrode for a discharge lamp according to any one of claims 1 to 7.

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