JP2001250505A - Sealing structure for electron tube and lamp using the sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oxidation of a functionally gradient material, when the material is used as a callus for sealing the opening portion of an electron tube. SOLUTION: An insulative quartz plate 16 is inserted into a slit 5, and a brazing material 7, such as Ag or Au, is applied on the edge of conductive parts 6a, 6a for the purpose of anti-oxidation. As a method of anti-oxidation, an insulative E-layer can be formed on the outermost layer, by changing the composition of the layer consecutively above a layer A in Figure (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed structure of an electron tube using a functionally gradient material, and a lamp such as a halogen lamp, a metal halide lamp, a cathode ray tube, and a vacuum tube using the sealed structure.

[0002]

2. Description of the Related Art For example, in the case of a metal halide lamp,
A luminescent substance is put in a translucent electron tube made of SiO2, Al2O3, etc., sealed with a closing body, and a high voltage is applied between the internal electrodes inserted in the electron tube via an external electrode, so that a high voltage is applied between the electrodes. An arc discharge is generated, and the heat generated by the arc discharge evaporates the luminescent material sealed in the electron tube, thereby emitting light having a specific color.

In the conventional structure of the above-described lamp sealing portion, there is a structure in which one electrode rod is penetrated into a closed body to form an internal electrode and an external electrode. In this structure, leakage occurs through a through hole. It's easy to do. In view of this, there is a type in which the internal electrode and the external electrode are separately press-fitted into a part of a closed body made of a cermet, so that conduction between the internal electrode and the external electrode is achieved by the conductivity of the cermet. In the case of using SiO2 as a tube material, the internal electrode and the external electrode are electrically connected via a molybdenum foil. At this time, sealing is performed by welding at both ends of the tube by heating.

However, due to the difference in thermal expansion between the cermet and the tube, after sealing the glass, cracks may occur in the sealed portion due to the generation of thermal stress, and the sealed gas may leak. Was. Also, in the case of sealing by welding, there is a problem that thermal stress is generated due to a difference in the thermal expansion coefficient between the electrode and the molybdenum foil, peeling is caused, and also a leak is caused. Therefore, the present applicant has previously made a proposal to solve these problems by forming the closing body with a functionally gradient material.

In the above proposal, a functionally graded material is produced by casting. That is, a slurry containing a ceramic powder and a metal powder is poured into a casting mold, and the composition ratio is continuously changed by using a specific gravity difference between the metal powder and the ceramic powder, and a gradient function having both an insulating portion and a conductive portion is provided. I try to make the ingredients.

[0006]

If the closing member is made of a functionally graded material as described above, it is possible to supply electricity to the internal electrodes while simplifying the structure and maintaining the sealing performance. However, in order to supply electricity to the internal electrodes, it is necessary to make a part of the closing body a conductive part, but when this conductive part is the outermost layer of the closing body, the conductive part is formed by oxygen in the air. Has the disadvantage of being oxidized.

[0007]

In order to solve the above-mentioned problems, a sealing structure for an electron tube according to the present invention is used as a closing body for sealing an opening of a light-transmitting electron tube, in which a ratio between a metal material and a ceramic material is gradually increased. Using a functionally graded material that changes to, at least a portion facing the outside of the electron tube of the closed body as a conductive portion,
Antioxidation means was applied to this conductive part.

The antioxidant means may be Ag or Au.
It is conceivable to apply a brazing material made of a material on the end face of the closing body or to form a layer made of a ceramic material on the end face of the closing body. In addition, as a lamp to which the sealing structure of the present invention is applied, a halogen lamp, a metal halide lamp, a cathode ray tube, a vacuum tube, and the like can be given.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to manufacture a functionally graded material constituting a closing body, first, a plurality of types of mixed powders having different mixing ratios of a ceramic powder and a metal powder are prepared. As ceramic powder, alumina, zirconia, magnesia, silica,
One or more powders selected from non-metallic compounds such as silicon carbide, titanium carbide, silicon nitride, and AlON, and the metal powders include at least one of metal particles such as molybdenum, nickel, tungsten, tantalum, and chromium. The powder may be appropriately selected and used. For example, SiO2 is selected as the ceramic powder and Mo is selected as the metal powder, and the specific mixing ratio is shown in the following (Table 1).

[0010]

[Table 1]

Here, when selecting the ceramic powder and the metal powder, it is considered that the sintering pattern and the sintering temperature of the two are close to each other. Further, for ceramic powder, a material having the same composition or thermal, mechanical, chemical properties and the like as a material to which the functionally gradient material is in contact, for example, a material constituting the electron tube, as a specific example, a thermal expansion coefficient is approximately Consider equality. They can use various glasses in addition to the above-mentioned ceramic powder. Although the present invention has an advantage by utilizing a specific gravity difference as described below, in particular,
Since a specific gravity difference is not required, a functionally graded material can be formed by combining more materials.

Further, the layers A and B in Table 1 are regions in which conductivity is exhibited.
0.1 Ω · cm or less, preferably 0.005 Ω · cm or less (room temperature to 7
(00 ° C.). As the layer, a layer of 100% Mo may be prepared.
In the case of Mo, sintering may proceed with Mo alone, and the consistency with the lower layer may be deteriorated. Therefore, it is preferable to mix SiO2 to some extent. This behavior is the same when other metals are used, in which case the selected ceramic powder is mixed. In the case of a Mo single layer, the thickness of the layer is set to 50 μm or less.

Further, if contamination (impurities such as Fe and Co) is mixed into the Mo powder, it may cause cracks during firing or the like, or cause deterioration of the durability of a product as an electron tube. Therefore, it is removed in advance. As a removing method, for example, 100 g of Mo powder is immersed in 0.1 N hydrochloric acid (another acid may be used) for 12 hours, then the solution is separated by a membrane filter, and Mo is washed several times with pure water. Then, it is dried at 70 ° C. for 6 hours.

Then, the mixed powder of the Mo powder and the SiO2 powder is wet-mixed for each mixed powder and granulated. Specifically, with respect to 100 g of the mixed powder, 0.6 g of PVB (polyvinylbutyral), 0.7 g of stearic acid, 0.07 g of naphthenic acid, and 100 g of acetone are used in a monopot,
Wet mixing at 36 rpm for 12 hours using a monoball,
Thereafter, spray drying is performed to obtain 50 to 100 μm spherical aggregates.

The spherical aggregate obtained as described above is filled into a mold 1 for each composition ratio as shown in FIG.
The order of filling is preferably such that the layer containing a large amount of SiO2 powder having a low specific gravity is placed below and the layer containing a large amount of Mo powder having a large specific gravity is placed above. By doing so, the composition at the boundary of each layer is mixed, and a continuous composition having no steps is obtained. In particular, according to this method, the composition is not three-dimensionally changed but a three-dimensionally (eg, corrugated) continuous one is obtained, and the boundary of each layer is resistant to thermal stress and excellent in strength. Becomes

Further, in order to mix and uniform the composition of the boundary of each layer, vibration may be applied after filling. This operation is more effective when the above specific gravity is considered.

After the mixed powder is filled into the mold 1 for each composition in this manner, the punch 2
Compressed with a load of m2 to obtain a molded body 3 as shown in FIG.

After that, the organic binder is removed from the molded body 3. The removal conditions are, for example, heating in an atmosphere of H2, O2, Ar, N2 or a mixture thereof, or under a reduced pressure atmosphere. As a heating pattern, the temperature was raised from room temperature to 600 ° C. over 3 hours, and then maintained at 600 ° C. for 1 hour.
The temperature was raised to 1300 ° C. over an additional hour,
Hold for hours.

FIG. 3 shows the compact 3 obtained as described above.
Processing is performed as shown in FIG. In this embodiment, the compact 3
Is used for closing the end opening of the electron tube,
Holes 4 and 4 for inserting internal electrodes and slits 5 for electrical insulation are formed.

The hole 4 into which the internal electrode is to be inserted is formed from the end face of the composition region (layer E) exhibiting insulation to a position close to the composition region (layers A and B) exhibiting conductivity. A hole is formed from a composition region exhibiting conductivity (layer A) to a position corresponding to a composition region exhibiting insulation (layer D). By forming the slit 5 in this manner, the portion 6 exhibiting conductivity becomes a plurality of electrically insulated conductive portions 6a, 6a.
Is separated into

In the figure, each layer is shown to have approximately the same thickness, but these thicknesses may be different. In particular, in order to more reliably seal the tube, the E layer, which is an insulating portion, must be replaced with another layer. Layer, or the layer A, which is a conductive portion, may be thicker than other layers in order to secure the reliability of conduction between the internal and external electrodes.

Next, the compact 3 having undergone the predetermined processing is sintered. As shown in FIG. 4, sintering is performed by using a sheath 7 made of Mo and Mo.
The molded body 3 is set in a space surrounded by a lid 8 made of a resin, the temperature is raised to 1720 ° C. over 6 hours, and maintained at 1720 ° C. for 5 minutes. Thus, a dense closed body made of the functionally graded material is obtained.

Then, as shown in FIGS. 5A and 5B, an insulating quartz plate 16 is inserted into the slit 5, and the end faces of the conductive portions 6a, 6a are made of Ag or Au for the purpose of preventing oxidation.
Is applied. Further, as shown in FIG. 6, the external electrodes 18, 18 may be press-fitted into the conductive portions 6a, 6a and fixed with a brazing material. Further, as the oxidation preventing means, the composition may be continuously changed further upward from the layer A in the figure, and an insulating E layer may be formed as the outermost layer. In this case, it is not necessary to increase the thickness of the E layer if only prevention of oxidation is intended.

FIG. 7 is a sectional view of a halogen lamp to which the sealing structure according to the present invention is applied.
The fired shaped body 3 (functionally graded material) obtained as described above is filled in the opening 12 of the electron tube 11 made of iO2 as a closing body. The internal electrodes 13 and 13 are press-fitted and held in holes 4 and 4 formed in the closing body 3 through a coil 14 made of tungsten, and the distal ends of the internal electrodes 13 and 13 are connected by a filament 15. The plurality of conductive portions 6a, 6a which are electrically insulated from each other are used as external electrodes as they are. When the electron tube 11 is made of SiO2, the closing member 3 is heated only without using a glass frit.
Can be welded to the electron tube 11.

[0025]

As described above, in the electron tube sealing structure according to the present invention, the ratio between the metal material and the ceramic material gradually changes as the closing member for sealing the opening of the translucent electron tube. Since the functionally graded material is used and the insulating part of this functionally graded material is arranged in the opening of the electron tube, the thermal expansion coefficient of the opening and the closing body can be approximated, and the durability against repeated turning on and off of the lamp Can be enhanced. Further, even if the conductive portions having different coefficients of thermal expansion are exposed outside the opening, there is no risk of deterioration because the antioxidant means is provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state where a mixed powder of a ceramic powder and a metal powder is filled in a mold with granulated powder.

FIG. 2 is a perspective view of a molded body molded by a mold.

FIG. 3 is a cross-sectional view showing a state where a molded body is processed.

FIG. 4 is a diagram showing a state in which a molded body is fired.

5A is a cross-sectional view of another embodiment of the closing body of the halogen lamp, and FIG. 5B is a top view of another embodiment of the closing body.

FIG. 6 is a sectional view of another embodiment of the closing body of the halogen lamp.

FIG. 7 is a sectional view of a halogen lamp to which the sealing structure according to the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die, 2 ... Punch, 3 ... Molded body, 4 ... Hole for inserting an internal electrode, 5 ... Slit for electrical insulation, 6 ... Portion exhibiting conductivity, 6a ... Electrically insulated Plural conductive parts, 11: electron tube, 13: internal electrode, 14: tungsten coil, 17: brazing material, 18: external electrode, A,
B: a layer exhibiting conductivity; C: an intermediate layer; D, E: layers exhibiting insulation.

Claims (6)

[Claims] 1. An electron tube sealing structure in which an opening of a translucent electron tube is sealed with a closing body, wherein the closing body is made of a functionally graded material in which a ratio between a metal material and a ceramic material is gradually changed. An electron tube sealing structure, characterized in that the body has an oxidation preventing means in a portion facing the outside of the electron tube. 2. An electron tube sealing structure according to claim 1, wherein said oxidation preventing means uses a brazing material made of Ag or Au. 3. An electron tube sealing structure according to claim 1, wherein said oxidation preventing means uses a layer made of a ceramic material. 4. A lamp in which an opening of a translucent electron tube is sealed with a closing body, wherein said closing body uses a functionally graded material in which a ratio between a metal material and a ceramic material is gradually changed,
A lamp having an antioxidant means at least at a portion of the closing body facing the outside of the electron tube. 5. The lamp according to claim 4, wherein said antioxidant means uses a brazing material made of Ag or Au. 6. The lamp according to claim 4, wherein said oxidation preventing means uses a layer made of a ceramic material.