TWI602216B - Manufacturing method of discharge lamp electrode and discharge lamp - Google Patents

Description

Method for manufacturing electrode for discharge lamp and discharge lamp

The present invention relates to a discharge lamp used in an exposure apparatus, and more particularly to a method of manufacturing an electrode for a discharge lamp in which a plurality of members are joined.

The discharge lamp is joined with a member having different metal types and crystal characteristics to form an electrode with high output. For example, a metal member containing an electron emitting material such as ruthenium is used as an electrode tip end portion, a high melting point metal member such as tungsten is used as a main body portion, and two metal members are joined to each other.

One method of solid phase bonding in the bonding method is called diffusion bonding. In the diffusion bonding, the crystal structure can be inclined in the axial direction in the vicinity of the joint surface, or the metal crystal grains can be joined without being deformed in the axial direction, and the deterioration of the electrode performance due to the joining can be suppressed (see Patent Documents 1 and 2). ). Next, discharge plasma sintering bonding (SPS bonding) was performed in accordance with a predetermined pressure, pressurization time, and bonding temperature to perform diffusion bonding.

Electrode forming in such diffusion bonding is to fix the electrode shape by cutting. For example, a cylindrical tantalum tungsten member constituting the pole tip end portion and a columnar tungsten member constituting the body portion are prepared. Then, the contact surfaces having the same length and length are abutted, and the pressure is applied while being applied 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 electricity. Polar shape (refer to Patent Document 3).

In the case where the solid phase is joined to a different metal member to form an electrode, since the thermal expansion rate is different, the joint surface in the lighting causes an extremely large stress, which may cause breakage of the electrode. In order to prevent this, an electrode is provided with an annular projection on the joint surface between the front end portion and the main body portion, and they are engaged with each other and diffusion bonded (see Patent Document 4).

On the other hand, there is a method of adjusting the area ratio of the side faces of the electrodes to increase the life of the lamps (see Patent Document 5). Wherein, tantalum tungsten is used as the front end portion of the electrode and is diffusion-bonded to the body portion of the pure tungsten. In the discharge lamp tube, the ratio of the side area of the tantalum tungsten portion to the electrode area is structurally set within a predetermined range. , can stabilize the arc discharge.

[Advanced technical literature]

Patent Document 1: JP-A-2011-249027

Patent Document 2: JP-A-2011-71091

Patent Document 3: JP-A-2012-15007

Patent Document 4: JP-A-2011-216442

Patent Document 5: JP-A-2011-154927

When a part of the electrode body is made of a metal containing an electron emitting material such as tantalum tungsten, the electron emitting material is supplied through the joint surface. Further, the structure of the joint surface such as the size of the joint surface, the smoothness of the joint surface, the joint condition at the time of solid phase joining, and the joint surface shape affect the electrode performance such as strength, conductivity, and thermal conductivity of the electrode.

For example, the length of the joint surface itself can also affect electrode performance. In the past, the effect of the length of the joint surface was not taken into account during the solid phase bonding, so the electrode performance decreased depending on the situation.

In addition, the joining temperature, the joining time, the pressing force, and the like are also different depending on the length of the joint surface. When the correlation between the bonding temperature, the bonding time, the pressure, and the length of the bonding surface is directly set, the desired electrode performance cannot be obtained.

Therefore, when the solid phase is joined to a plurality of members to form an electrode, it is desirable to set the connection temperature, the bonding time, the pressure, and the correlation between the lengths of the joint surfaces, and set a set value that can achieve excellent electrode performance.

On the other hand, the cross section of the tantalum tungsten member is lower than the smoothness of the cross section of the tungsten member. The difference in smoothness is more pronounced as the path length is longer. Therefore, the joint strength on the joint surface becomes uneven, and stable joint strength cannot be obtained.

When the bonding is performed by the energization heating, the current easily flows to the surface side depending on the bonding conditions and the like, and the vicinity of the periphery of the bonding surface is larger than the bonding strength of the center portion. Therefore, if the front end portion is formed by cutting after the diffusion bonding, the portion near the surface having a large joint strength is much cut, so that the joint strength is lowered.

Therefore, it is necessary to form a solid phase bonding in which the member containing the electron emitting material such as tantalum tungsten which constitutes the tip end portion and the member constituting the main body portion are stably joined.

In addition, the structure of the joint surface also affects the movement of the electron emissive material. The movement of the electron emissive material toward the front end side of the electrode tip end in the lamp lighting is based on the diffusion of the grain boundary to the surface of the electrode and along the electrode table The concentration of surface diffusion is diffused. The direction of movement of the grain boundary diffusion has no directivity, so the distribution of electron-emitting substances moving to the surface of the electrode is not uniform. When the surface is moved along the surface in the circumferential direction of the distal end portion and then diffused by the surface concentration to the distal end surface side of the electrode tip end portion, the supply of the electron emitting material is extremely time consuming.

The diffusion rate varies depending on the electrode temperature, and the supply amount of the electron emissive material moving toward the front end surface side of the electrode tip end portion is unstable, and the concentration of the electron emissive material near the tip end portion of the electrode is uneven. As a result, the bright spot of the arc discharge easily moves to a place where the concentration of the electron emissive material is high, and the illumination becomes flickering and unstable.

Therefore, it is necessary to supply the electron emitting material to the front end surface side of the electrode tip end portion as efficiently as possible, and to uniformize the electron emissive material concentration at the tip end portion of the electrode.

A method for producing an electrode for a discharge lamp according to the present invention includes: a columnar tip solid member comprising at least a part of an electrode tip end portion and containing an electron emissive material; and at least an electrode main body portion, wherein a diameter of the joint surface is larger than the front end solid The columnar main body solid members having a long diameter on the joint surface of the member are solid-phase bonded through the joint surfaces, and the electrode material produced by the solid phase joining is subjected to cutting processing to form a tapered electrode tip end portion.

For example, the electrode can be a cathode that is used in a discharge tube after fabrication. The electron emissive material may be tantalum tungsten or the like, and the front end solid member or the bulk solid member may have any shape. The material may be a metal material or a ceramic material. The solid phase bonding method can employ various diffusion bonding, particularly solid phase bonding in an SPS bonding mode.

In the present invention, the diameter of the front end solid member is greater than the bulk solid member The length of the path. On the other hand, after the solid phase bonding, the electrode is formed, and the electrode formed can efficiently remove only the end portion of the joint surface where the wedge portion is easily formed and the joint strength is weak.

For example, in the cutting step, the counter electrode material cuts at least the peripheral portion of the joint surface of the front end solid member and the body solid member. In particular, it is possible to cut the electrode material and remove the wedge portion formed on the peripheral edge portion of the joint surface of the distal end solid member. It is also possible to cut the electrode material so that only the center portion of the joint surface of the front end solid member is left.

In order to be able to perform such cutting, the ratio of the radial length of the joint surface of the distal end solid member to the radial length of the joint surface of the solid body member can be set to 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 includes: forming a front end portion having a convex portion or a concave portion (hereinafter referred to as a convex portion/recessed portion), and having a convex portion fitting the front end portion/ a concave portion of the concave portion and a main portion of the convex portion; and the front end portion is in contact with the main body portion to perform SPS bonding, wherein the front end portion is partially solid-bonded to the main body portion during the SPS bonding.

In order to partially perform the solid phase bonding, for example, at least one of the bonding time, the sintering/bonding temperature, and the applied voltage when the electrode tip end portion and the opposing surface of the body portion are all solid-phase bonded is set or changed. Thereby, the solid phase bonding is partially performed, and the convex portion and the concave portion having the opposing faces formed at least along the surface along the vertical electrode axis direction generate a portion where the solid phase is not joined.

A discharge lamp tube manufactured by such a manufacturing method includes an electrode tip end portion including an electron-emitting substance and having a convex portion or a concave portion, and a main body portion having a concave portion or a convex portion fitted to a convex portion or a concave portion of the electrode distal end portion. The tip end portion of the electrode is provided with a front end surface which is a bright spot of the arc discharge, and the electrode is reduced in diameter such as a conical shape. At least part of the ministry. The body portion may be, for example, a columnar shape, or a part of the electrode tip end portion may be formed.

The electrode tip end portion can be made of, for example, tantalum tungsten, and the body portion can be made of, for example, pure tungsten or the like. The place where the convex portion and the concave portion are formed may be arbitrarily selected, and a concave portion or a convex portion may be formed along the direction of the electrode axis, and a surface facing each other may be formed in a direction other than the direction perpendicular to the vertical electrode.

The convex portion and the concave portion may have a shape that can be fitted to each other, and a plurality of convex portions, concave portions, or a plurality of convex portions and concave portions may be provided. Whereas the chimeric representations herein match each other, and the opposing faces of such shapes are substantially in contact with one another (not referring to molecular grades but under macroscopic viewing). For example, the shape of the convex portion/recess portion may be a columnar shape such as a cylinder, a triangular prism, or a quadrangular prism.

In the present invention, the tip end portion of the electrode is partially solid-phase bonded to the body portion. In the plurality of faces facing the front end portion of the electrode and the body portion, at least a part of the convex portion/concave portion of the electrode tip end portion and the concave portion/convex portion of the body portion facing each other are not solid-phase bonded.

In the convex portion and the concave portion, there is a portion that is not joined by the solid phase. Therefore, in the lamp lighting, the movement of the 钍 component moving based on the grain boundary diffusion in the non-solid phase joining portion is restricted toward the vertical electrode axis direction. As a result, most of the bismuth component moving in the direction perpendicular to the electrode axis cannot reach the electrode surface, and moves toward the front end surface of the electrode tip end portion earlier.

The formation place of the convex portion and the concave portion can be arbitrarily selected. For example, the convex portion/concave portion of the electrode tip end portion and the concave portion/convex portion of the body portion can be formed coaxially with respect to the electrode axis. In this case, the erbium component that has escaped to the entire tip end portion of the electrode can be collectively moved toward the distal end surface side of the electrode tip end portion.

In consideration of the supply of the bismuth component, the opposite faces of the concave portion and the convex portion are not solid-phase bonded, and the solid phase bonding is performed, whereby the electrode strength can be improved. That is, the electrode tip end portion and the body portion can be solid-phase bonded to surfaces facing each other in a direction perpendicular to the electrode axis at positions other than the convex portion/concave portion of the electrode tip end portion and the concave portion/convex portion of the body portion.

A method of manufacturing an electrode for a discharge lamp according to another aspect of the present invention includes: forming a plurality of solid members having at least one metal member, including a front end side solid member having an electrode front end face, and being supported by the electrode support rod An end-side solid member; and a solid-state joint between the front-end side solid member and the rear-end side solid member, wherein when the joint surface outer diameter L (mm) is in the range of 2≦L≦60, Solid phase bonding is carried out in such a manner as to satisfy the following conditions.

3000≦Tt+P≦150093

(1200≦T≦2500,10≦P≦90,3≦t≦60) where L is the joint outer diameter (mm), T is the joint temperature (°C), and P is the applied pressure (MPa) at the time of joining, t is the bonding time (min) at which the metal member is held under pressure.

Alternatively, in the method for producing an electrode for a discharge lamp according to another aspect of the present invention, the solid phase bonding satisfies 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≦t≦60

The above formula 2 sets the setting range of the variables L, T, P, and t capable of sufficiently maintaining the joint strength, and is empirically derived, and the set variables have correlation with each other.

If the individual variables are reviewed, the joint outer diameter L, the joint temperature T, It is preferable that the pressing pressure P and the joining time t satisfy the following conditions.

5≦L≦30,1500≦T≦2200,30≦P≦80,5≦t≦30

As a plurality of solid members, at least one of them may be a metal member. The front end side solid member and the rear end side solid member joined to the front end side solid member may be formed and formed before joining. The front end side solid member may be a metal member containing niobium. The solid phase bonding can be performed by SPS bonding.

According to the present invention, an electrode having excellent electrode performance can be produced based on solid phase bonding.

10‧‧‧Discharge lamp

12‧‧‧Discharge tube

13A, 13B‧‧‧ sealed tube

15A, 15B‧‧‧ guide bars

16A, 16B‧‧‧metal foil

17A, 17B‧‧‧electrode support rod

19A, 19B‧‧‧ metal cover

20, 120, 220‧‧‧ cathode

120A, 220A, 2120A‧‧‧ front end

120B, 220B, 2120B‧‧‧ body parts

30‧‧‧Anode

40, 50, 1110, 1120, 2120‧‧‧ metal components

1110T‧‧‧The Peripheral Department

1110C‧‧‧Central Department

1200‧‧‧electrode material

40A‧‧‧Conical trapezoidal part

40B‧‧‧ cylindrical part

40S, 220S‧‧‧ electrode front end face

60‧‧‧Discharge plasma sintering device

65‧‧‧vacuum chamber

70A‧‧‧Upper punch electrode

70B‧‧‧ lower punch electrode

80‧‧‧ die

80A‧‧‧Upper punch

80B‧‧‧lower punch

90‧‧‧ pulse power supply

222, 225‧‧‧Continuous surface

222A, 222B, 222C, 222D, 222E, 225A, 225B, 225C, 225D, 225E, 2122A, 2122B, 2122C, 2122D, 2122E, 2125A, 2125B, 2125C, 2125E, 2125E‧‧‧

223, 2126‧‧‧ convex

226, 2123‧‧‧ recess

DS‧‧‧discharge space

S, 1110S, 1120S, 2120S‧‧‧ joint surface

S1, S2‧‧‧ fields

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

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

Fig. 3 is a view showing a discharge plasma sintering apparatus.

Fig. 4 is a view showing the conditional expression (1).

Fig. 5 is a view showing conditional expression (2).

Fig. 6 is a schematic cross-sectional view showing a cathode of a second embodiment.

Figure 7 is a diagram showing the manufacturing steps of the cathode.

Fig. 8 is a schematic cross-sectional view showing a cathode of a third embodiment.

Fig. 9 is a schematic plan view showing the front end portion and the main body portion before joining.

Figure 10 is a schematic plan view of a cathode.

Figure 11 is a schematic plan view of a cathode of a fourth embodiment.

Fig. 12 is a view showing the coordinate positions and conditional expressions of the examples and comparative examples in Table 1. (1) The map of the field.

Fig. 13 is a view showing the coordinates of the coordinates of each of the examples and the comparative examples and the conditional expression (2).

Fig. 14 is a partial enlarged view of Fig. 13.

Embodiments of the present invention will be described below with reference to the drawings.

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

The short-arc discharge lamp tube 10 is a light source that can be used in an exposure device (not shown) for forming a pattern, and includes a discharge tube (light-emitting tube) 12 made of transparent quartz glass. The cathode 20 and the anode 30 in the discharge tube 12 are opposed to each other at a predetermined interval.

On both sides of the discharge tube 12, the sealed tubes 13A, 13B made of quartz glass facing each other are integrally provided with the discharge tube 12, and both ends of the seal tubes 13A, 13B are plugged by the metal covers 19A, 19B. In the discharge lamp tube 10, the anode 30 is disposed on the upper side and the cathode 20 is disposed on the lower side in the vertical direction. The anode 30 is composed of two metal members 40 and 50 as will be described later.

Conductive electrode support rods 17A and 17B for supporting the metallic cathode 20 and the anode 30 are disposed inside the sealed tubes 13A and 13B, and the metal foils 16A and 16B through the metal ring (not shown) and molybdenum are respectively connected to the conductivity. Guide bars 15A, 15B. The sealed tubes 13A and 13B are welded to glass tubes (not shown) provided in the sealed tubes 13A and 13B, thereby sealing the discharge space DS in which mercury and an inert gas are sealed.

The guide bars 15A and 15B are connected to an external power supply unit (not shown), and voltages are applied between the cathode 20 and the anode 30 through the guide bars 15A and 15B, the metal foils 16A and 16B, and the electrode support bars 17A and 17B. If power is supplied to the discharge lamp 10, electricity An arc is generated between the poles, and a bright line (ultraviolet light) generated by mercury is emitted.

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

The anode 30 is an electrode structure that joins the metal members 40, 50. The metal member 40 is composed of a conical trapezoidal portion 40A including an electrode front end face 40S, and a cylindrical portion 40B having the same diameter as the cylindrical metal member 50 and joined to the metal member 50. Composition. The metal member 40 is made of a high melting point such as pure tungsten or an alloy whose main component is tungsten.

On the other hand, the metal constituting the cylindrical metal member 50 contains a metal having a higher thermal conductivity than the metal member 40 (for example, pure tungsten, tantalum, molybdenum, a getter having a gettering effect, and high heat conductivity can be formed. Aluminum nitride, carbon, etc.).

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

Here, only the crystal grains of the joint surface contributing to the joining are partially deformed, and the crystal grains in the vicinity of the joint surface S are hardly deformed in the direction (electrode axis direction) along the vertical joint surface, based on The secondary recrystallization of the grain is enlarged and the grain boundary moves. Further, the crystal grain size along the joint surface is almost uniform, and the crystal grain size in the vicinity of the joint surface along the electrode axis direction is also almost uniform.

Forming the diffusion layer adjacent to the joint surface S makes it possible to prevent unevenness along the joint surface S from heat conduction characteristics and electrical conductivity. During the period in which the electrode tip end surface 40S (1000 ° C or higher) which is heated to a high temperature is transferred to the electrode support rod 17B due to the lighting of the lamp, the temperature distribution inside the anode is symmetrically distributed around the electrode axis X, and heat transfer is not received. The influence of the joint surface S.

On the other hand, the metal crystal diameter becomes slightly uniform along the joint surface S, and diffusion bonding can be performed to tilt the crystal structure along the electrode axis X. Because of the tilting, 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 in the second drawing. Other metal members may be present between the metal members 40, 50 at the time of solid phase bonding.

Fig. 3 is a view showing a discharge plasma sintering apparatus.

The discharge plasma sintering method is a sintering method in which a pulse electric energy is directly supplied to a particle gap of a powder compact or a molded body, and high-temperature energy of a discharge plasma instantaneously generated in a spark discharge phenomenon is used for thermal diffusion, electric field diffusion, or the like.

The discharge plasma sintering apparatus 60 of Fig. 3 includes a vacuum chamber 65, and has a shape of the second figure between the upper punch 80A, the lower punch 80B, and the graphite die 80 inside the vacuum chamber 65. The metal members 40 and 50 are disposed in a state in which they are in contact with each other. When the metal members 40 and 50 are molded, metal processing is performed by prior cutting or the like to form the contact faces to have the same size.

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 evacuating the inside of the apparatus, the pulse power supply 90 applies a voltage between the upper punch 80A and the lower punch 80B.

Then, while energizing, a pressure is applied between the upper punch 80A and the lower punch 80B by a pressurizing mechanism (not shown). After the discharge plasma generated by the energization is instantaneously heated to a predetermined temperature, the state in which the pressure is applied is maintained for a certain period of time. Thereby, an anode having the shape shown in Fig. 2 was obtained.

Next, the bonding conditions at the time of electrode production will be described using Figs. 4 and 5 .

As described above, when the SPS joins the metal members 40, 50, the joining temperature, The pressing force and the joining/holding time are predetermined. The setting of these parameters can greatly affect the performance of the electrode. Further, these parameters have a correlation with the radial length of the joint surface, and in order to obtain the most appropriate conditions, it is necessary to set the joint outer diameter, the joint temperature, the pressing force, and the joining time to appropriate values.

In the present embodiment, an appropriate value of each parameter is obtained and an expression indicating the correlation between the parameters is derived. By setting the parameters that satisfy the derived conditional expression, it is possible to automatically obtain an electrode structure excellent in electrode performance to some extent without setting the parameters in a heuristic manner.

First, the joint outer diameter L (mm) is set to satisfy 2≦L≦60. When the outer diameter L of the joint surface is less than 2 mm, the pressurization at the time of joining cannot be increased, and partial discharge is slightly generated outside the joint surface, and the joint is unstable. If the pressurization at the time of joining is increased, the metal material before joining is likely to be cracked or deformed. In addition, the diffusion of helium occurs, which reduces the amount of helium and reduces the performance of the lamp. On the other hand, if the outer diameter L of the joint surface is larger than 60 mm, the processing required for obtaining the smoothness of the joint surface becomes complicated, and the amount of the crucible used is too large.

The bonding temperature T (° C.) at the time of bonding is set to satisfy 1200 ≦ T ≦ 2500. When the bonding temperature T is larger than 2500 ° C, the melting point (about 1800 ° C) of the crucible is greatly exceeded, and a part of the crucible contained in the uppermost layer in the vicinity of the joint surface is melted and evaporated. When the flaw of the joint surface spreads, the joint strength is lowered. On the other hand, when the joining temperature T is less than 1200 ° C, sufficient joint strength cannot be obtained.

The pressing force (MPa) at the time of joining is set to satisfy 10 ≦ P ≦ 90. When the pressing force P is higher than 90 MPa, the metal member is easily broken or deformed at the time of joining. Since the two metal members must be facing and pressed on the same axis, once the direction of the press is deviated, the joint surface may be bent or sunken, so that the joint surface is nearby. The density becomes uneven. On the other hand, when the pressing force is less than 10 MPa, sufficient joint strength cannot be obtained.

Then, regarding the metal member holding time at the time of joining, that is, the joining time t (min), it is set to satisfy 3 ≦ t ≦ 60. If the holding time t is longer than 60 minutes, the productivity is lowered. On the other hand, if the holding time t is less than 3 minutes, sufficient joint strength cannot be obtained.

As a result, the joint outer diameter L, the temperature T, the pressing force P, and the joining time t at the time of SPS joining are set within a numerical range in which excellent electrode performance can be achieved. However, there is a correlation between these parameters, and it is quite difficult to determine a combination of parameters that can achieve excellent electrode performance while changing each parameter separately.

Therefore, in the present embodiment, two conditional expressions are defined. The numerical ranges satisfying the conditional expression are graphically respectively, thereby visualizing the four parameter ranges.

First, a conditional expression that considers the energy at the time of joining is defined as follows: 3000≦Tt+P≦150093.....(1)

(2≦L≦60)

The joint temperature T, the pressing force P, and the joining time t satisfying the upper limit value and the lower limit value of the formula (1) are set while changing the outer diameter L of the joint surface.

Fig. 4 is a view showing the conditional expression (1). As shown in Fig. 4, a two-dimensional coordinate system defining the horizontal axis L and the vertical axis Tt+P is defined, and the range satisfying the formula (1) is patterned into the domain S1. The joint strength is different depending on the coordinate position of (L, Tt + P) in the rectangular area S1.

Next, the conditional expression for considering the joint strength is defined as follows: 370.4/L≦α/L≦15857.1/L.....(2)

(α=(T+P)t/9.8, 2≦L≦60)

Fig. 5 is a view showing conditional expression (2). As shown in Fig. 5, a two-dimensional coordinate system defining the horizontal axis L and the vertical axis (T+P) t/(9.8 L) is defined, and the field S2 is patterned.

By patterning the possible setting ranges of the respective parameters as described above and manufacturing the electrodes having different electrode structures, that is, electrodes having different outer diameters of the joint faces, it is possible to easily derive and set values having excellent thermal conductivity and strength.

In particular, the joint outer diameter L, the joining temperature T, the pressing force P, and the joining time t are set in the following ranges, whereby an electrode having more excellent electrode performance can be produced.

5≦L≦30,1500≦T≦2200,30≦P≦80,5≦t≦30.....(3)

According to the present embodiment, the SPS joins the metal member 40 containing a component such as ruthenium and the metal member 50 such as pure tungsten to form an anode. At the time of SPS joining, the joint outer diameter L, the joining temperature T, the pressing force P, and the joining time t are set within the above-defined limited range, and the values satisfying the conditional expressions (1) and (2) are set.

Alternatively, the electrode may be fabricated by a diffusion bonding method other than SPS bonding. For example, hot-pressing (HP), hot isostatic pressing (HIP), and the like are used to produce an electrode by diffusion bonding while sintering. Further, a solid phase bonding method (such as a friction bonding method or an ultrasonic bonding method) other than the diffusion bonding method can also be applied.

The cathode can also be formed by solid phase bonding of different metal members. Alternatively, one of the two members that perform solid phase bonding may be a solid phase joint using a metal member and the other member (ceramic or the like) made of another material. In addition, other insertion members may be interposed between the members to be joined.

Next, the discharge lamp of the second embodiment will be described using Figs. tube. In the second embodiment, the members having different radial lengths are solid-phase bonded to form an electrode.

Fig. 6 is a schematic cross-sectional view showing a cathode of a second embodiment.

The cathode 120 has an electrode structure in which two metal members 1110 and 1120 are joined and formed by cutting. The metal member 1110 constitutes a part of the front end portion 120A. The metal member 1120 constitutes a columnar body portion 120B and constitutes a portion on the body side of the tip end portion 120A.

The metal member 1110 is a metal member composed of tungsten (i.e., tantalum tungsten) containing cerium oxide (ThO ₂ ). The metal member 1120 is composed of a metal having a higher thermal conductivity than the metal member 1110 (here, pure tungsten).

The metal members 1110 and 1120 are diffusion bonded by SPS (Spark Plasma Sintering). 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 almost uniform along the joint surface S. On the other hand, regarding the electrode axis E, the crystal diameter is slightly uniform except for the vicinity of the joint surface S. The diffusion layer that is adjacent to the joint surface S is formed so that thermal conductivity and electrical conductivity are not uneven along the joint surface.

Figure 7 is a diagram showing the manufacturing steps of the cathode. Use Figure 7 to illustrate SPS bonding and cutting. Further, the anode can also be produced in the same manner.

First, cylindrical metal members 1110 and 1120 are formed, respectively. At this time, the diameter D1 of the metal member 1110 is formed to be shorter than the diameter D2 of the metal member 1120. Here, when 3 < D1 < 30, 5 < D2 < 60 (units are mm), the path lengths D1 and D2 are set so as to satisfy 0.05 < D1/D2 < 1. The upper limit value is set to eliminate at least the wedge portion described later. The lower limit value depends on the inclination angle of the tip end portion of the electrode, the joining condition, and the like.

For the prepared metal members 1110, 1120, with the implementation type 1 In the same place, the SPS bonding process is performed. Thereby, the electrode material 1200 is obtained.

The resulting electrode material 1200 is then subjected to a cutting process. Here, the metal members 1110 and 1120 are partially cut, respectively, to form a conical electrode front end surface indicated by a broken line K. The metal member 1110 is cut out from the center portion (except the peripheral portion 1110T) of the joint surface 1110S, and the metal member 1120 is a peripheral portion where the joint surface 1120S is cut away. The cutting method, the cutting tool, and the like are performed by a conventional method, an instrument, or the like.

The position of the cut surface indicated by the broken line K, that is, the position at which the outer peripheral surface of the electrode is formed is the magnitude and difference of the diameters D1 and D2 of the metal members 1110 and 1120, the inclination angle of the outer peripheral surface of the electrode, and the thickness of the metal member 1110. It depends on the same. In particular, it is set to remove at least the joint surface peripheral portion 1110T of the metal member 1110, leaving the joint surface central portion 1110C.

The electrode material 1200 after cutting is composed of a conical metal member 1110 and a metal member 1120 in which a part of the conical shape is a columnar shape. As shown in Fig. 6, a cathode 120 composed of an electrode tip end portion 120A and a body portion 120B is formed.

According to the present embodiment, the cathode 120 of the discharge lamp having the electrode tip end portion 120A made of tantalum tungsten is joined by SPS bonding. In the SPS joining step, the cylindrical metal member 1110 made of tantalum tungsten and the cylindrical metal member 1120 of pure tungsten having a diameter D2 longer than the diameter D1 of the metal member 1110 are electrically heated by the joint surfaces 1110S and 1120S. SPS bonding. Thereafter, the cutting process is performed so that the cross section indicated by the broken line K becomes the electrode outer peripheral surface.

The joint surface 1110S of the metal member 1110 containing the niobium component is lower than the smoothness of the joint surface 1120S of the metal member 1120 of pure tungsten. This gap follows the trail The bigger the more the more significant. However, since the diameter D1 of the joint surface 1110A which is shorter than the diameter D2 of the joint surface 1120 is relatively small, this influence is not easily exhibited after the solid phase joining, and the decrease in the joint strength can be suppressed.

Because of the difference in physical properties of the metal members 1110, 1120, a portion of the micro-wedge portion that is not joined in the vicinity of the end of the joint surface is generated in the vertical direction of the electrode axis. In the present embodiment, by cutting the joint surface peripheral portion 1110T of the metal member 1110, the wedge portion formed on the joint peripheral portion 1110T at the time of SPS joining can be removed. This result can suppress the decrease in the joint strength.

In particular, the cutting portion of the metal member 1110 can be reduced as much as possible only in the range where the wedge portion is removed, and the diameter D1 of the metal member 1110 can be further brought closer to the diameter D2 of the metal member 1120. This can increase the pressing force at the time of SPS joining and increase the joint strength.

On the other hand, when the SPS is energized, the joint strength of the central portion of the joint surface may be smaller than the joint strength of the vicinity of the outer peripheral surfaces of the metal members 1110 and 1120 depending on the joining conditions and the like. However, since the diameter D1 of the metal member 1110 is relatively small, this influence is also small. Further, the range of the vicinity of the outer periphery of the metal member 1110 having a large cutting joint strength is relatively reduced. Therefore, the joint strength of the center portion is increased as compared with the case where the contact faces of the same diameter are in contact with each other.

In the metal member 1110 made of tantalum tungsten, there may be a case where a portion where no cerium oxide is present is generated 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 joining, it is possible to prevent the arc discharge from being unstable due to the lack of cerium oxide. In addition, since the cutting process is performed after the SPS is joined, there is no height difference in the radial direction of the joint surface. This result does not cause abnormal discharge when the lamp is lit.

The diameter of the arbitrary metal member, the inclination angle of the tip end surface of the electrode, and the cross-sectional shape of the tip end surface can be used to cut a flat outer peripheral surface having no height difference, and a tapered electrode tip end portion can be formed. Further, the material and shape of any metal member may be employed, and the electrode tip portion of the solid member may contain an electron emissive material other than ruthenium. The main body portion may be formed of a material other than a metal member (ceramic, carbon, or the like). Further, the electrode tip end portion may be configured to include a solid member including an electron emissive material member such as tantalum tungsten and a main portion.

Next, the discharge lamp of the third embodiment will be described using Figs. 8 to 10. In the third embodiment, a height difference is provided on the joint surface, and partial solid phase joining is performed.

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

The cathode 220 has a structure in which a tapered trapezoidal tip end portion 220A having an electrode tip end surface 220S is joined to a columnar body portion 220B. The front end portion 220A is a metal composed of tantalum tungsten containing an antimony component as an electron emissive material, and the main body portion 220B is made of a metal having high thermal conductivity (here, pure tungsten) or an alloy containing the metal.

The distal end portion 220A is provided coaxially with respect to the electrode axis E at its central portion with a convex portion 223 that protrudes toward the main body portion side. The body portion 220B has a recess 226 that fits the shape of the protrusion 223. The front end portion 220A and the main body portion 220B are solid-phase bonded to form a cathode 220. Here, SPS bonding using one of the diffusion bonding methods is employed.

As shown in Fig. 9, the front end portion 220A and the main body portion 220B have contact surfaces 222 and 225 which are formed by a plurality of end faces and face each other. Front end portion 220A side shape End faces 222A and 222E perpendicular to the electrode axis E, an end face 222C of the convex portion 223, and end faces 222B and 222D of the parallel electrode axis E are formed. End faces 225A to 225E that face the end faces 222A to 222E of the distal end portion 220A are formed on the main body portion 220B side.

In the SPS joining process step, the convex portion 223 of the distal end portion 220A is fitted to the concave portion 226 of the main body portion 220B, and then abuts against a surface of the opposite side of the convex portion 226 (not shown). The convex portion 223 of the distal end portion 220A and the concave portion 226 of the main body portion 220B are fitted in a state in which none of the end faces 222B to 222D and 225B to 225D abuts without a gap, and the cathode 220 is obtained.

In the manufacturing steps of the electrode for a discharge lamp, SPS bonding is performed in the same manner as in the first embodiment. The applied voltage, the pressing force, the joining temperature, and the pressing time (holding time) in the SPS joining are adjusted so that the convex portion 223 of the front end portion 220A and the concave portion 226 of the main body portion 220B are not fixed between the end faces 222B to 222D, 225B to 225D. The surfaces are joined (diffusion bonding), and the circumferential end faces 222A and 222E and the annular end faces 225A and 225E are respectively bonded to each other.

For example, when the diameter M (mm) of the cathode 220 is set to 5 ≦ M ≦ 30, the applied voltage V, the pressing force P (MPa), the sintering temperature T (° C.), and the joining time t (min) are respectively set. The SPS bonding was performed in the range of 5 ≦ P ≦ 30, 1500 ≦ T ≦ 2200, and 5 ≦ t ≦ 30 to obtain the above-described partially solid phase bonded cathode 220.

Fig. 10 is a schematic plan view of a cathode 220. Use Figure 10 to illustrate the movement of the 钍 component in the lamp lighting.

When switching to the lamp lighting state, the bismuth component (specifically, cerium oxide) inside the front end portion 220A moves toward the surface based on grain boundary diffusion. The movement of the components does not exceed the end faces of each other because the inside of the convex portion 223 or the convex portion 223 The end surface 222D and the concave portion 226 of the main body portion 220B are only simply abutted, so they only move along the surface.

Since the convex portion 223 and the concave portion 226 are not solid-phase bonded to each other, the components of the crucible are often moved toward the front end surface of the electrode. In other words, it becomes an obstacle that the bismuth component moves in the direction of the vertical electrode axis E, and the 钍 component mainly moves toward the electrode front end surface 220S as it moves toward the surface (conical surface) along the circumferential direction of the distal end portion 220A. .

As a result, the inner crucible component reaches the electrode front end face 220S quickly and early with a relatively short total distance. In particular, since the convex portion and the concave portion are provided in the central portion, the ruthenium component dispersed inside the distal end portion 220A is supplied to the distal end surface 220S in a balanced manner, and the influence of the sputum concentration in the vicinity of the distal end surface 220S with time is reduced, and tends to be stable.

Further, since the ridge component can be more stored in the convex portion 223 than the shape of the distal end portion of the convex portion 223, the convex portion can be relatively low in temperature even if the temperature of the distal end portion is increased due to the lighting condition. The portion 223 sufficiently supplies the tantalum components to the front end side in order.

According to this embodiment, the cathode 220 of the discharge lamp tube is composed of a front end portion 220A formed of tantalum tungsten and a main body portion 220B formed of pure tungsten. The convex portion 223 of the distal end portion 220A is fitted to the concave portion 226 of the main body portion 220B, and then SPS is joined. At this time, the convex portions 223 and the concave portions 226 are not solid-phase bonded, and the other end faces 222A, 225A, 222E, and 225E are solid-phase bonded.

The convex portion 223 and the concave portion 226 are in close contact with each other as much as possible without leaving a gap, and even when the front end portion 220A and the main body portion 220B are formed, a sufficiently smooth end surface is formed. However, it is not necessary to make the convex portion 223 and the end of the concave portion 226 The surface is strictly smoothed, and the surface roughness is not affected even if a minute void is partially formed. Further, the convex portion 223 and the concave portion 226 may be partially solid-bonded as long as at least a part of the end surface or a part of either end surface remains in a state in which solid phase bonding is not performed.

Next, a discharge lamp of the fourth embodiment will be described using Fig. 11 . In the fourth embodiment, the uneven shape is formed in the reverse direction, and the other structures are the same as those in the third embodiment.

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

The cathode 2120 is composed of a front end portion 2120A and a main body portion 2120B. The front end portion 2120A has a concave portion 2123, and the main body portion 2120B has a convex portion 2126. In the front end portion 2120A and the main body portion 2120B, the end faces 2122A and 2125A and the end faces 2122E and 2125E which face each other are joined to each other in a solid state. On the other hand, the recessed portion 2123 and the projection 2126 are not joined to each other by solid phase bonding, and are abutted by fitting.

With this configuration, when the lamp is turned on, the crucible component inside the distal end portion 2120A moves toward the surfaces 2122B and 2122D of the concave portion 2123, and then moves toward the distal end surface 2120S, whereby the crucible component can be efficiently supplied to Front end face 2120S.

The structure of the front end portion 2120A has the concave portion 2123, so heat is easily transmitted to the front end surface 2120S. Therefore, even when the temperature of the front end portion 2120A is low, the enthalpy component can be stably supplied.

Hereinafter, embodiments of the invention will be described. Here, in order to examine the conditional expressions (1) and (2), an anode as a plurality of examples and comparative particles was produced, and an experiment was conducted.

[Examples]

The discharge lamp of the first embodiment corresponds to the discharge lamp of the first embodiment. With respect to the conditional expression (1), an anode having a tip end portion of a tantalum tungsten member and a body portion of a pure tungsten member was produced by SPS bonding. At this time, Examples 1 to 3 and Comparative Examples 1 to 3 were produced by changing the joint outer diameter L, the joining temperature T, the pressing force P, and the joining time t, respectively. Thereafter, tensile tests were performed on each of the manufactured anodes. The results of the experiment are shown in Table 1.

Example 1 and Comparative Example 1 are electrodes manufactured by directly SPS joining a tantalum tungsten member and a pure tungsten member without interposing an intermediate member. Example 2 and Comparative Example 2 are electrodes in which a tantalum (Ta) member was inserted as an intermediate member and SPS bonding was performed. Example 3 and Comparative Example 3 are electrodes in which an erbium (Re) member was inserted as an intermediate member and SPS was joined.

In the tensile test, the gripper of the material testing machine was used to hold both ends of the electrode and stretched at a speed of 10 mm/min to test the force at break.

Figure 12 shows the coordinates of the examples and comparative examples in Table 1. And a diagram of the field of conditional expression (1).

As shown in Fig. 12, the first to third embodiments are included in the field S1. Further, it can be seen from Table 1 that the tensile strength is very strong. In contrast, Comparative Examples 1 to 3 did not belong to the field S1 and the tensile strength was weak. The electrode was deformed in the tensile test due to excessive bonding energy. You can also see the spread of 钍.

By setting the joint outer diameter L, the joining temperature T, the pressing force P, and the joining time t within the range of the field S1 as described above, excellent electrode performance can be obtained.

Next, with respect to Conditional Formula (2), an electrode having a tip end portion of a tantalum tungsten member and a body portion of a pure tungsten member was produced by SPS bonding. At this time, Examples 5 to 8, 11 to 15, and Comparative Examples 1 to 4 and 9 to 10 were produced by changing the joint outer diameter L, the joining temperature T, the pressing force P, and the joining time t, respectively. Thereafter, tensile tests were performed on each of the manufactured anodes. The results of the experiment are shown in Table 2. However, the difference from Table 1 is that the numbers of the examples and comparative examples are assigned here in the order of manufacturing and experiment.

Fig. 13 is a view showing the coordinates of the coordinates of each of the examples and the comparative examples and the conditional expression (2). Fig. 14 is a partial enlarged view of Fig. 13.

The numbers of the examples in Table 2 and the numbers of the comparative examples can be seen from the figures of Figs. 13 and 14, and all the comparative examples are outside the range of the field S2. As can be seen from Table 2, in the comparative example, enthalpy diffusion, insufficient bonding strength, or deformation of the electrode occurred. On the other hand, in all of the examples, the bonding strength was large, and excellent electrode performance was obtained.

In the above embodiment, a structure in which the tip end portion of the tantalum tungsten is joined to the tungsten body portion is used. However, the same result can be obtained by performing SPS bonding between the other metal solid members.

With regard to the present invention, various changes, substitutions or substitutions may be made without departing from the spirit and scope of the invention. The present invention is not intended to be limited to the specific procedures, apparatus, manufacture, compositions, means, methods and procedures described in the specification. It will be apparent to those skilled in the art that the devices, means, and methods that can substantially achieve the functions of the embodiments described herein, or substantially equivalent functions and effects, can be derived. Therefore, the scope of the patent application is intended to cover the scope of such apparatus, means, and methods.

This case is based on the Japanese application (Japanese Patent Application No. 2012-208372, September 21, 2012; Special Request 2012-212807, September 26, 2012; The application for priority is based on the application of the 2012-214630, September 27, 2012 application. The contents of the basic case, the drawings and the contents disclosed in the patent application are incorporated herein by reference.

10‧‧‧Discharge lamp

12‧‧‧Discharge tube

13A, 13B‧‧‧ sealed tube

15A, 15B‧‧‧ guide bars

16A, 16B‧‧‧metal foil

17A, 17B‧‧‧electrode support rod

19A, 19B‧‧‧ metal cover

20, 120, 220‧‧‧ cathode

DS‧‧‧discharge space

Claims (7)

A method for manufacturing an electrode for a discharge lamp, comprising the steps of: forming a columnar front end solid member constituting at least a part of an electrode tip end portion and containing an electron emitting material, and at least forming an electrode body portion, and a diameter of the joint surface is longer than the front end solid a cylindrical main body solid member having a long diameter on a joint surface of the member is solid-phase bonded through the joint surfaces; and the electrode material formed by the solid phase joining is subjected to cutting processing to form a tapered electrode tip portion, wherein the electrode In the material, at least a peripheral portion of the joint surface of the front end solid member and the body solid member is cut. The method for producing an electrode for a discharge lamp according to the first aspect of the invention, wherein the front end solid member is a metal member containing ruthenium. The method for producing an electrode for a discharge lamp according to claim 1, wherein when the outer diameter L (mm) of the joint surface is in the range of 2 ≦ L ≦ 60, solid phase bonding is carried out in such a manner as to satisfy the following conditions. : 3000 ≦ Tt + P ≦ 150093; 1200 ≦ T ≦ 2500, 10 ≦ P ≦ 90, 3 ≦ t ≦ 60; where L is the joint outer diameter (mm), T is the joint temperature (°C), P is the joint The applied pressing force (MPa) and t are bonding times (min) for holding the electrode material under pressure. The method for producing an electrode for a discharge lamp according to claim 1, wherein the solid phase bonding is performed in a manner of satisfying the following conditions: 370.4 / L ≦ (T + P) t / 9.8 L ≦ 15857.1/L; ≦L≦60,1200≦T≦2500,10≦P≦90,3≦t≦60; Where L is the outer diameter (mm) of the joint surface, T is the joining temperature (°C), P is the pressing force (MPa) applied at the time of joining, and t is the joining time (min) of holding the electrode material under pressure. The method for producing an electrode for a discharge lamp according to any one of claims 3 to 4, wherein the joint outer diameter L, the joint temperature T, the pressing force P, and the joining time t satisfy the following condition: 5≦L≦ 30, 1500 ≦ T ≦ 2200, 30 ≦ P ≦ 80, 5 ≦ t ≦ 30. The method for producing an electrode for a discharge lamp according to any one of claims 3 to 4, wherein at least one of the front end solid member and the main body solid member is a metal member. A discharge lamp tube comprising the electrode for a discharge lamp tube produced by the method for producing an electrode for a discharge lamp according to any one of claims 1 to 6.