JP2010205627A - Gas discharge lamp electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive long-life gas discharge lamp electrode which can be manufactured easily and in which stable electron emission from a cathode can be achieved. <P>SOLUTION: This gas discharge lamp electrode is equipped with the cathode consisting of an electron-emissive sintered body having a spire on one end, and a high melting point metal chip, in which as for the high melting point metal chip, the tip end side on a side corresponding to the one end of the electron-emissive sintered body is embedded in the electron-emissive sintered body, and the rear end side opposing to the tip end side has a protruding part to protrude from the rear end opposing to the one end of the electron-emissive sintered body, and a shape of the tip of the high melting point metal chip has the tip three-dimensional angle approximated to the tip end three-dimensional angle of the spire of the electron emissive-sintered body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode of a gas discharge lamp (lamp) used for a light source used for illumination, a measuring instrument or the like.

  2. Description of the Related Art Conventionally, it is known to use a gas discharge lamp electrode as a light source or the like used for illumination or a measuring instrument.

  FIG. 1 is a cross-sectional view in which a part of an example of a gas discharge lamp provided with such a gas discharge lamp electrode is omitted.

  A hollow gas enclosure is formed in a glass bulb 1 made of quartz glass, and a discharge gas such as xenon is enclosed therein. A cathode 2 and an anode 3 are placed opposite to each other in a gas sealing part in the glass bulb 1. The cathode 2 and the anode 3 are electrically connected to external terminals provided at both ends (left and right ends in FIG. 1) of the glass bulb 1 via molybdenum foil 4 and leads 5, respectively. In the embodiment of FIG. 1, a base 7, an adhesive 6, a nut 8, and a trigger wire 9 attached for the purpose of improving discharge performance are also illustrated.

  When a voltage is applied between the cathode 2 and the anode 3 from the external terminals provided at both ends (left and right both ends in FIG. 1) of the glass bulb 1, arc discharge occurs between the cathode 2 and the anode 3 A light is emitted.

  As the cathode 2 of this discharge lamp (lamp), an electrode having a structure in which an electron emission portion sintered body, which is an impregnated type electrode impregnated with an electron-emitting substance, is attached to the tip of a refractory metal rod has been conventionally employed. (Patent Document 1).

  The electron emission part sintered body, which is an impregnated electrode impregnated with the above-mentioned easy electron emitting material, is impregnated with a porous high melting point metal (for example, tungsten) with an easy electron emitting material (for example, alkaline earth metal). The refractory metal powder and the electron-emitting material powder are press-molded and fired in vacuum or in a hydrogen atmosphere (Patent Document 2).

As the above-mentioned easy electron emitting materials, those in which BaO, CaO, Al ₂ O ₃ are mixed in a ratio of 4 to 1 are known. Thus, the easy electron emitting materials (for example, alkaline earth metals, etc.) are known. A barium-impregnated electrode made of a sintered body of an electron emission portion obtained by impregnating barium with a high melting point metal such as tungsten is conventionally known as a cathode of a discharge lamp (lamp).

  Since the lamp cathode having this conventional structure uses a rod-like refractory metal as the base portion of the electrode, it is difficult to increase the contact area between the impregnated electrode constituting the electrode body and the refractory metal rod. . For this reason, there is a problem that the heat transfer efficiency between the impregnated electrode and the refractory metal rod is low, and it is difficult to efficiently dissipate the heat generated in the impregnated electrode.

  In order to improve this, the refractory metal rod serving as the base portion of the electrode is provided with an end face having a convex portion, and the convex portion is inserted into the concave portion formed in the impregnated electrode, so that the impregnated electrode and the refractory metal rod are inserted. Increasing the contact area between the two was investigated. However, when such a structure is used, a gap is generated between the refractory metal rod and the impregnated electrode, and the heat dissipation efficiency may not be sufficiently improved. In addition, if the electron emissive material remaining in the gap evaporates as the temperature rises when the discharge lamp is used and adheres to the wall surface of the discharge lamp, there is a risk of reducing the output light amount of the discharge lamp and shortening the life of the discharge lamp. there were.

  In order to improve these, a refractory metal rod having an end face formed with a convex portion and a refractory metal containing an electron-emitting material, having a pointed end on one end and the high melting point on the other end An impregnated electrode having an end surface in which a concave portion for inserting a convex portion of the metal rod is formed, the end surface of the refractory metal rod being larger than the end surface of the impregnated electrode, and the end surface of the refractory metal rod and the impregnated type There has been proposed a discharge tube electrode in which a gap between the end face of the electrode is closed with a brazing material (Patent Document 3).

  Further, regarding an impregnated cathode with a conductive support in which a projecting portion of a conductive support is attached to a mounting recess formed in the impregnated cathode and a manufacturing method thereof, there are inconveniences associated with the use of a brazing material at the time of attachment, There has also been a proposal aimed at eliminating the influence on the various characteristics of the impregnated cathode due to the presence of a gap between the protruding portion of the conductive support and the mounting recess formed in the impregnated cathode ( Patent Document 4).

  This is because, after embedding the protruding portion of the refractory metal conductive support in the refractory metal powder, the refractory metal powder is compression-molded into a cathode shape, and the thus obtained molded with conductive support The porous sintered body and the conductive support are integrated by melting and impregnating the electron-emitting material into the porous sintered body made of the molded body obtained in this sintering process. It is what. As a result, the ratio of the joint area to the mating area (joining rate) is increased to suppress power loss at the mating surface, and a large number of fusion joints are formed on the mating surface between the porous sintered body and the conductive support. To provide uniform and symmetrical electron supply in the impregnated cathode to make the distribution of emitted electrons uniform, to improve radiation characteristics, and to have a solid structure by having a large number of fusion joints on the mating surface It is said that it is possible to eliminate inconveniences associated with the use of the brazing material at the time of attachment, by realizing real joining and directly melting and joining the sintered particles and metal without using inclusions such as brazing material.

No. 4-3388 Japanese Patent Application Laid-Open No. 11-288689 JP 2000-215845 A Patent Publication Showa 63-119130

  In the impregnated electrode, when the temperature on the tip side cannot be uniformly controlled, it is difficult to realize stable electron emission. In addition, when the heat generated in the impregnated electrode cannot be efficiently dissipated, the electron-emitting material evaporates as the temperature rises on the impregnated electrode tip side, adheres to the wall surface of the discharge lamp, decreases the output light amount of the discharge lamp, There is a risk of shortening the life of the discharge lamp.

  In the conventional impregnated electrode and the connection structure between the conventional impregnated electrode and the refractory metal rod, the heat generated in the impregnated electrode is efficiently dissipated, and the temperature on the tip side of the impregnated electrode is further increased. There was room for improvement in achieving uniform electron emission with stable control.

  Further, as described above, when the electron emitting portion sintered body is joined to the tip of the refractory metal rod with a brazing material to form a discharge lamp (lamp) cathode, the porous refractory metal (e.g., tungsten) has an easy electron. Since the temperature for impregnating the radioactive material (for example, alkaline earth metal) is high, it is necessary to use a high melting point material for the brazing material.

  Therefore, conventionally, molybdenum-ruthenium (Mo—Ru) brazing material or the like has been generally used. The Mo—Ru brazing material has a melting point of 1880 ° C. and satisfies the required high melting point, but has a problem that the temperature control range is narrow, so that there are many restrictions on production and it is expensive.

  Accordingly, the present invention provides an impregnated electrode that efficiently dissipates the heat generated in the impregnated electrode, enables more stable control of the temperature on the tip side of the impregnated electrode, and realizes stable electron emission. Propose a connection structure between the electrode and the refractory metal rod, and can be manufactured more easily than before, stable electron emission from the cathode can be realized, and long-life and inexpensive gas The object is to provide a discharge lamp electrode.

In order to solve the above problems, the invention according to claim 1 of the present application is
A gas discharge lamp electrode comprising a cathode composed of an electron emitting portion sintered body having a tip at one end and a refractory metal tip,
The refractory metal tip is:
A tip side corresponding to the one end of the electron emission portion sintered body is embedded in the electron emission portion sintered body, and
The rear end side facing the front end side is a projecting portion protruding from the rear end facing the one end of the electron emission portion sintered body,
The tip of the refractory metal tip has a solid tip angle that approximates the tip solid angle of the tip of the electron emission portion sintered body.

The invention according to claim 2
2. The tip shape of the refractory metal tip has a tip solid angle with a tolerance dimension of ± 20 degrees with respect to the tip solid angle of the tip of the electron-emitting portion sintered body. It is a gas discharge lamp electrode of description.

The invention described in claim 3
The protruding portion of the refractory metal tip is inserted into a recess formed at the tip of a base material made of the same refractory metal, and is connected by electric welding to form a cathode. Item 3. The gas discharge lamp electrode according to Item 1 or 2.

  According to the present invention, the impregnated electrode that efficiently dissipates the heat generated in the impregnated electrode, and realizes stable electron emission by more uniformly controlling the temperature on the tip side of the impregnated electrode, and the impregnated mold A connection structure between the electrode and the refractory metal rod can be provided. In addition, it is possible to provide a gas discharge lamp electrode that can be easily manufactured as compared with the prior art, can realize stable electron emission from the cathode, and has a long life and is inexpensive.

Sectional drawing which abbreviate | omitted one part explaining an example of the discharge lamp by which the gas discharge lamp electrode of this invention is employ | adopted. The figure explaining an example of the structure of the cathode tip which comprises the gas discharge lamp electrode of this invention. (A) The figure showing the state before a cathode tip is connected to a rod-shaped refractory metal base material, (b) The figure showing the state where the cathode tip is connected to a rod-shaped refractory metal base material. The figure explaining an example of the process of connecting a cathode tip to a rod-shaped refractory metal base material.

  Hereinafter, in the case of a barium-impregnated electrode comprising a sintered body of an electron emitting portion using barium as an electron-emitting substance and impregnated with a porous refractory metal, preferred embodiments of the present invention will be described with reference to the accompanying drawings. A form is demonstrated.

  In the gas discharge lamp electrode of the present invention, a cathode tip 13 is connected to the tip of a rod-like refractory metal base material 17 to constitute a cathode indicated by reference numeral 2 in FIG. The other structures are the same as those illustrated and described with reference to FIG. 1, and therefore, the same reference numerals are used for the portions described with reference to FIG. 1 and description thereof is omitted.

  In the present invention, the cathode tip 13 includes an electron emitting portion sintered body 10 and a refractory metal tip 12 as shown in FIGS.

  The electron emitting portion sintered body 10 has a peak 11 at one end (the upper end in FIG. 2, that is, the tip).

  The tip side 14 of the refractory metal chip 12 (the side corresponding to the tip of the electron emission portion sintered body 10 and the upper side in FIGS. 2 and 3) is embedded in the electron emission portion sintered body 10. ing. The refractory metal tip 12 includes a protruding portion 15 that is formed integrally with the distal end side 14. The protrusion 15 is provided on the rear end side (the lower side in FIGS. 2 and 3) of the refractory metal chip 12 facing the front end side 14, and is shown in FIGS. Thus, it protrudes from the rear end (lower end in FIG. 2) facing the front end of the electron emission portion sintered body 10.

  The cathode tip 13 is manufactured by applying a conventional method for manufacturing an electron emission portion sintered body, which is an impregnated electrode impregnated with an electron-emitting material, for example, as follows. it can.

  A portion corresponding to the electron emitting portion sintered body 10 of the mold corresponding to the shape of the cathode tip 13 shown in FIGS. 2 and 3 is filled with powder of a refractory metal (for example, tungsten). Next, the refractory metal tip 12 is attached to a position where the tip side 14 of the refractory metal tip 12 is embedded in the electron emission portion sintered body 10. Then, press molding is performed so that the tip side 14 of the refractory metal chip 12 having the protruding portion 15 integrally formed on the rear end side is embedded in the electron emission portion sintered body 10. Next, an easy electron emitting material (for example, barium) is applied to the surface of the electron emission portion sintered body 10 and melted and impregnated in a vacuum or in a hydrogen atmosphere. After that, the removal of the easy electron emitting material remaining on the surface is performed. In this way, as shown in FIG. 2, the cathode tip chip 13 including the electron emission portion sintered body 10 and the refractory metal tip 12 is molded by sintering.

  By producing the cathode tip 13 in this manner, the tip side 14 including the tip 16 of the refractory metal tip 12 is formed inside the electron emitting portion sintered body 10 as shown in FIGS. Is engaged.

  On the other hand, the protruding portion 15 integrally formed on the rear end side of the refractory metal chip 12 protrudes from the rear end of the electron emission portion sintered body 10 and is a rod-shaped refractory metal serving as a base material constituting the cathode. This is used for welding when the cathode tip 13 is connected to the tip of the base material 17.

  Further, the protruding portion 15 has a cathode tip that operates at a high temperature when the cathode tip 13 is connected to the tip of the rod-shaped refractory metal base material 17 to constitute the cathode indicated by reference numeral 2 in FIG. It plays the role of a heat sink that efficiently releases the heat at the tip of the chip 13.

  In the present invention, the front end side 14 including the front end 16 is engaged with the inside of the electron emission portion sintered body 10 and is formed on the rear end side of the refractory metal chip 12 which is sintered and molded together with the electron emission portion sintered body 10. The projecting portion 15 formed integrally has the function of the heat sink described above. As a result, the heat generated at the tip 11 of the electron emitting portion sintered body 10 is quickly released to the tip 16 of the refractory metal tip 12 so that the temperature at the tip surface of the cathode tip 13 can be uniformly controlled at a desired temperature. ing.

  The shape of the tip 16 of the refractory metal tip 12 is as shown in FIG. 2 so that heat generated at the tip 11 of the electron emitting portion sintered body 10 can be quickly released to the tip 16 of the refractory metal tip 12. The sintered body 10 has a tip solid angle θ2 that approximates the solid angle θ1 of the tip of the peak 11.

  The inventor of the present application embeds the front end side 14 including the front end 16 of the refractory metal chip 12, in which the protruding portion 15 is integrally formed on the rear end side, embedded in the sintered portion 10 of the electron emission portion. In the cathode tip 13 sintered together with the electron emitting portion sintered body 10, the shape of the tip 16 of the refractory metal tip 12 and the shape of the tip 11 of the tip 11 of the electron emitting portion sintered body 10 are as follows. The present inventors have found that there is a relationship in efficiently dissipating the heat at the tip of the cathode tip 13 that operates at a high temperature and controlling the heat at the tip of the cathode tip 13 more uniformly.

  That is, in the cathode tip 13 having such a structure, the shape of the tip 16 of the refractory metal tip 12 is set to a solid angle θ1 at the tip 11 of the tip 11 of the electron emission portion sintered body 10, as shown in FIG. The electron emitting portion sintered body 10 is combined with the heat sink function by the protruding portion 15 integrally formed on the rear end side of the refractory metal chip 12 as described above by having the approximate solid end angle θ2. It has been found that the heat generated at the tip 11 can be quickly released to the tip 16 of the refractory metal tip 12.

  By having the tip solid angle θ2 that approximates the solid angle θ1 as described above, heat sink heat dissipation during lighting of the discharge lamp is good, and a long-life light source that does not contaminate the lamp window material can be provided.

  From this point of view, the shape of the tip 16 of the refractory metal chip 12 is such that the tip solid angle θ2 (θ1 ± 20) having a tolerance dimension of ± 20 degrees with respect to the tip solid angle θ1 of the tip 11 of the electron emission portion sintered body 10. More desirable). It should be noted that when θ2 is smaller than θ1 by more than 20 degrees or when θ2 is larger than θ1 by more than 20 degrees, the heat sink heat balance is lost and the life becomes unstable.

  As described above, the cathode tip 13 is filled with a predetermined material such as tungsten powder in a predetermined mold, and the refractory metal tip 12 is attached to the tip 12 of the refractory metal tip 12. It shape | molds by press and baking so that it may be embedded in the electron emission part sintered compact 10. FIG. Accordingly, the shape of the tip 16 of the refractory metal tip 12 is approximated to the shape of the tip 11 of the tip 11 of the electron-emitting portion sintered body 10 molded by the mold, thereby making the refractory metal tip 12. The shape of the tip 16 can be easily adjusted to have a tip solid angle θ2 that approximates the tip solid angle θ1 of the tip 11 of the electron emission portion sintered body 10.

  Further, in the impregnated electrode of the present invention and the connection structure between the impregnated electrode and the refractory metal rod, the refractory metal chip 12 in which the protruding portion 15 is integrally formed on the rear end side is provided with an electron. The distal end side 14 including the distal end 16 having a shape having a distal end solid angle θ2 that approximates the distal end solid angle θ1 of the tip 11 of the emitting portion sintered body 10 is embedded in the electron emitting portion sintered body 10. In addition to being meshed and sintered together with the electron emission portion sintered body 10, the wall thickness W between the electron emission portion sintered body 10 and the projecting portion 15 shown by hatching in FIG. It is desirable to make it.

  That is, the function of the heat sink by the protrusion 15 integrally formed on the rear end side of the refractory metal chip 12 is effectively exerted, and the heat generation at the peak 11 of the electron emission portion sintered body 10 is quickly performed at the high melting point. By letting the tip 16 of the metal tip 12 escape to uniformly control the temperature of the tip surface of the cathode tip 13 at a desired temperature, the electron emitting portion sintered body 10 and the projecting portion shown by hatching in FIG. It is advantageous to keep the wall thickness W between 15 constant.

  As described above, the heat at the tip of the cathode tip 13 that operates at a high temperature quickly escapes from the tip 11 of the electron emission portion sintered body 10 to the tip 16 of the refractory metal tip 12 and functions as a heat sink. The metal chip 12 escapes through the protruding portion 15 on the rear end side. Here, if the wall thickness W between the electron emitting portion sintered body 10 and the projecting portion 15 indicated by oblique lines in FIG. 2 is kept constant, heat is uniformly transmitted from the tip of the cathode tip 13. Thereby, the temperature of the tip surface of the cathode tip 13 can be controlled more uniformly at a desired temperature.

  In the present invention, the cathode tip 13 is filled with a predetermined material such as tungsten powder in a predetermined mold as described above, and a refractory metal tip 12 is attached to the cathode tip 13. It shape | molds by press and baking so that the front end side 14 may be embedded in the electron emission part sintered compact 10. FIG. Therefore, by attaching the refractory metal tip 12 so that the thickness W between the electron emitting portion sintered body 10 and the protruding portion 15 shown by oblique lines in FIG. Can be easily adjusted.

  As described above, the tip side including the tip 16 of the refractory metal tip 12 having a tip solid angle θ2 that approximates the tip solid angle θ1 of the tip 11 of the electron emission portion sintered body 10. 14 is meshed with the inside of the electron emission portion sintered body 10 and sintered and molded together with the electron emission portion sintered body 10. It quickly escapes from the tip 11 of the body 10 to the tip 16 of the refractory metal tip 12, and efficiently escapes to the protrusion 15 integrally formed on the rear end side of the refractory metal tip 12.

  As a result, according to the electrode of the present invention, the heat at the tip of the cathode tip 13 that operates at a high temperature can be efficiently released. That is, the heat generated at the peak 11 of the electron emission portion sintered body 10 can be quickly released (heatsinked) to the tip 16 of the refractory metal tip 12. Therefore, it becomes possible to uniformly control the temperature of the tip surface of the cathode tip 13 at a desired temperature. Thus, according to the present invention, it is possible to provide a cathode chip that performs stable electron emission.

  The step of connecting the cathode tip 13 manufactured as described above to the tip of a rod-shaped refractory metal base material 17 manufactured independently of the cathode tip 13, and the impregnated type electrode and the height The connection structure between the melting point metal rod is, for example, as follows.

  As shown in FIG. 4, the protrusion 15 integrally formed on the rear end side of the cathode tip 13 is formed at the tip of the refractory metal base material 17 and has a shape corresponding to the protrusion 15. It inserts into the recessed part 18 currently formed. Next, the joint is sandwiched between the welding electrodes 20a and 20b of the electric spot welder 19 as shown in FIG. 4, and both are connected by electric welding.

  In this case, since electrical welding of metals of the same material is easy to connect, the refractory metal tip 12 having the protruding portion 15 on the rear end side and the refractory metal base material 17 are made of the same material. This is advantageous. For example, both can be made of molybdenum.

  As described above, according to the present invention, when attaching the electron emitting portion sintered body 10 which is an impregnated electrode impregnated with an easily electron emitting material to the tip of the refractory metal rod 17, brazing using a refractory brazing material is performed. There is no need to perform the work, and the welding work can be easily performed by a conventionally known electric welding.

  Further, since an expensive high melting point brazing material is not used, the cathode 2 (FIG. 3B) can be manufactured at a low cost and without using an extra material. As a result, as the temperature rises when the discharge lamp is used, excess material used at the time of producing the cathode does not evaporate and adhere to the wall surface of the discharge lamp. As a result, it is possible to supply an inexpensive light source with a long life without polluting the window material of the discharge lamp.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such embodiments, and can be modified in various forms within the technical scope grasped from the description of the scope of claims. It is.

DESCRIPTION OF SYMBOLS 1 Glass bulb 2 Cathode 3 Anode 13 Cathode tip 17 Rod-shaped refractory metal base material 10 Electron emission part sintered body 12 Refractory metal chip 11 Tip of electron emission part sintered body 14 Tip of refractory metal tip Side 15 Projection 18 Recess 19 formed at the tip of the refractory metal base material Electric spot welding machine 20a, 20b Welding electrode

Claims (3)

A gas discharge lamp electrode comprising a cathode composed of an electron emitting portion sintered body having a tip at one end and a refractory metal tip,
The refractory metal tip is:
A tip side corresponding to the one end of the electron emission portion sintered body is embedded in the electron emission portion sintered body, and
The rear end side facing the front end side is a projecting portion protruding from the rear end facing the one end of the electron emission portion sintered body,
A gas discharge lamp electrode, wherein a shape of a tip of the refractory metal tip has a tip solid angle that approximates a tip tip solid angle of the electron emission portion sintered body.   2. The tip shape of the refractory metal tip has a tip solid angle having a tolerance dimension of ± 20 degrees with respect to a tip solid angle of the tip of the electron emission portion sintered body. The gas discharge lamp electrode as described.   The protruding portion of the refractory metal tip is inserted into a recess formed at the tip of a base material made of the same refractory metal, and is connected by electric welding to form a cathode. Item 3. A gas discharge lamp electrode according to Item 1 or 2.

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