JP2001093402A - Structural body for side heated immersed cathode and cathode-ray tube using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve boding strength of a high melting point metallic porous base body which constituted a structural body for a side heated immersed cathode with a cup-shaped holder, and to secure reliability of the bonding, and to greatly improve efficiency in a bonding work, and to provide a cathode-ray tube of high brightness, high resolution, and a long life. SOLUTION: A structural body for a cathode comprises a cathode pellet 4 wherein a thermoelectron emitting substance 3 is immersed in a high melting point metallic porous base body 1, a cup-shaped holder 2 which is bonded with planes other than an electron emission plane 1c of the high melting point metallic porous base body 1, a heater 6 whose head portion faces the cup-shaped holder 2, and a sleeve 5 which is bonded with a sidewall of the cup-shaped holder 2, wherein the cup-shaped holder 2 has an inner base 2a that is bonded with a base 1b opposite to the electron emission plane 1c of the high melting point metallic porous base body 1 and has a concave area 1c for forming a fine clearance between the bonded two bases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor tube for an OA equipment terminal, a cathode ray tube such as a cathode ray tube for a TV set including a projection type, and an image pickup tube for broadcasting. The present invention relates to an indirectly heated impregnated cathode structure that can be maintained for a long time and has a long service life, and a cathode ray tube having the indirectly heated impregnated cathode structure.

[0002]

2. Description of the Related Art A cathode ray tube of this type, for example, a color cathode ray tube used for a monitor of an OA equipment terminal, generally has a panel coated with a phosphor, a neck for accommodating an electron gun, and a funnel for connecting the panel to the neck. Having a vacuum envelope consisting of

In the electron gun used in the above-mentioned cathode ray tube, an indirectly heated impregnated cathode structure is known as a cathode structure as a component thereof. This indirectly heated impregnated cathode structure is suitable for a cathode having a high current density, and a barium (B) is formed on a porous substrate of tungsten, which is one of the refractory metals.
a), calcium (Ca), aluminum (Al)
In the case of using a cathode pellet impregnated with a thermionic emission material composed of a source oxide, and in order to further improve the electron emission characteristics, osmium (Os) and ruthenium (Ru) are deposited on the electron emission surface of the cathode pellet. One type or those coated with a thin film of these alloys are available.

[0004] Such an indirectly heated impregnated cathode structure is used in cathode ray tubes such as cathode ray tubes used in large-screen TVs, such as monitors for OA equipment terminals, which require high brightness and high resolution characteristics, and image pickup tubes. It has a high thermionic emission current density that can be used to meet the required properties of these cathode ray tubes, and has a property that the high current density property can be maintained for a long time such as tens of thousands of hours.

However, since the indirectly heated impregnated cathode structure is used at a high operating temperature of 1000 to 1100 ° C., the structure of the structure is considered to be highly reliable. Are known (for example, Japanese Patent No. 2735955).

FIG. 8 is a schematic sectional view showing an example of a conventional indirectly heated impregnated cathode structure disclosed in the above-mentioned Japanese Patent No. 2,735,955. Is manufactured by the following method. First, after a compact having a predetermined shape made of a high melting point metal powder such as tungsten or molybdenum is compression-molded, this is sintered to obtain a high melting point metal porous substrate 81. At the same time, the cup-shaped holder 82, the sleeve 8
3. The heater 84 is manufactured.

[0007] Thereafter, the high melting point metal porous substrate 81 is inserted into the cup-shaped holder 82 such that the bottom surface 81b opposite to the electron emission surface 81a faces the inner bottom surface 82a of the cup-shaped holder 82. In a state where the refractory metal porous substrate 81 is strongly pressed against the inner bottom surface 82a of the cup-shaped holder 82, a laser beam is applied to the outer bottom surface 82b of the cup-shaped holder 82 by means of laser welding.
Both are welded by spot welding. At this time, it is desirable to form several points, for example, about 4 to 6 welding portions SW1. As a result, the refractory metal porous substrate 81 has a structure in which substantially the entire surface except the surface serving as the electron emission surface 81a is covered by the cup-shaped holder 82.

Next, the high-melting metal porous substrate 81 is impregnated with a thermionic emission material such as barium, calcium, aluminate or the like by a usual method, and after the impregnation is completed, the high-melting metal porous material is formed by a shot peening method. Substrate 81
The excess impregnated residue adhering to the surface of the substrate is removed to form a cathode pellet 85. Next, the combined body of the cup-shaped holder 82 and the cathode pellet 85 is connected to one end 8 of the sleeve 83.
After insertion into 3a, it is welded and fixed via the side surface of the sleeve 83 by laser beam welding or resistance welding. SW2 in FIG. 8 indicates the welding site at that time.

Another conventional method for producing an indirectly heated infiltrated cathode structure is as follows: before the high-melting-point metal porous substrate and the cup-shaped holder are fixed to each other by welding, an electron-emitting material is previously applied to the high-melting-point metal porous substrate. A method of impregnation has also been proposed.

Further, as a method of fixing the cup-shaped holder and the high-melting-point metal porous substrate, there is a method in which a tape is provided on a side surface of the cup-shaped holder, and the high-melting-point metal porous substrate is fixed by caulking. It is disclosed in Japanese Unexamined Patent Publication No. 1-225033.

[0011]

Although such an indirectly heated impregnated cathode structure can provide stable high current density characteristics and stable operation for a long period of time, the conventional structure has the following disadvantages.
First, a cup-shaped holder 82 having a cathode pellet 85
Is fixed by welding with the sleeve 83 by laser beam welding, since all parts are made of a high melting point metal material, even a one-dimensional melting heat becomes a high temperature of about 2000 ° C., and the impregnated thermoelectrons The release material is violently blown out, and as a result, the welding trace of SW2 becomes a perforated state, so that there is a problem in securing the reliability of welding and fixing, and the perforated state is caused by the indirectly impregnated cathode structure. During use, thermionic emission material blows out from the hole and becomes a fatal defect that contaminates the surroundings of the cathode structure, and there is a problem that the life of the cathode ray tube itself as well as the indirectly heated impregnated cathode structure cannot be extended. .

This is exactly the same in the above-mentioned welding and fixing of the high-melting-point metal porous substrate and the cup-shaped holder by laser beam welding. However, there is a fatal defect that blows out from the hole and contaminates the periphery of the cathode structure, and there is a problem that not only the indirectly heated impregnated cathode structure but also a long life of the cathode ray tube itself cannot be secured.

In the case of the resistance welding, the resistance between the parts to be welded is utilized at a shallow part of the surface of the part by utilizing the resistance between the parts.
In this method, the parts are welded to each other in a very short time of several minutes, and the whole part is not heated to a high temperature. Therefore, it is possible to avoid the violent ejection of thermionic emission material. Since the indirectly heated impregnated cathode structure is composed of a combination of relatively small components, the opposing surfaces of the high-melting-point metal porous substrate and the cup-shaped holder are both flat during resistance welding, and the tips of the welding electrodes are also flat. If the parallelism between the parts to be welded is not adjusted without deviation, uneven pressing force acts between the welding electrode and the welded parts, resulting in lack of uniformity of welding. Further, there is a problem that the parallelism needs to be adjusted for each welding, and the working efficiency is extremely low.

Further, according to the caulking described above,
Since the target indirectly heated impregnated cathode structure itself is a small part of about 1 mm, it cannot be an optimal means and has a problem in reliability.

An object of the present invention is to provide an excellent indirectly heated impregnated cathode structure which solves the above-mentioned problems of the prior art, and a cathode ray tube using the indirectly heated impregnated cathode structure.

[0016]

In order to achieve the above object, the present invention provides a structure having a minute gap in a fixing surface between a refractory metal porous substrate and a cap-shaped holder, the thermoelectron emission associated with perforation. An object of the present invention is to prevent contamination around the cathode structure by a substance, to improve the fixing strength of both, and to ensure the reliability of the fixing, and to provide a long-life indirectly heated impregnated cathode structure and a cathode ray tube.

Typical configurations of the present invention are as follows. (1) A cathode pellet in which a high-melting-point metal porous substrate is impregnated with a thermionic emission material; a cup-shaped holder fixed to the other surface of the high-melting-point metal porous substrate except for the electron emission surface; An indirectly heated impregnated cathode structure having a holder and a heater having its head opposed to each other, and a sleeve fixed to a side wall of the cup-shaped holder, wherein an inner bottom surface of the cup-shaped holder is formed of the refractory metal. The porous substrate was fixed to the bottom surface opposite to the electron emission surface, and a small gap was formed in the fixed surface.

(2) The minute gap in (1) is formed by one or both concave portions of the bottom surface of the refractory metal porous base and the inner bottom surface of the cup-shaped holder.

(3) A substantially central portion of the bottom surface of the cup-shaped holder in (1) is projected toward the refractory metal porous substrate.

According to the above-mentioned constitutions (1) to (3), the presence of a minute gap in the fixing surface between the high-melting-point metal porous substrate and the cup-shaped holder improves the fixing strength of both and improves the reliability of the fixing. The insulated property can be ensured, and a long-life indirectly heated impregnated cathode structure can be obtained.

(4) In (1), the tip of the cup-shaped holder on the opening end side surrounding the high-melting-point metal porous substrate is receded from the electron emission surface of the high-melting-point metal porous substrate.

According to this structure, when the porous metal substrate having a high melting point and the cup-shaped holder are fixed to each other, the contact therebetween is good, so that the fixing strength can be improved and the fixing reliability can be ensured. The space between the cathode structure and the first electrode is not dimensionally limited by the protrusion of the upper end of the cathode structure, and the degree of freedom in design is increased.

(5) A method of manufacturing an indirectly impregnated cathode structure in which an electron emitting material is impregnated into a refractory metal porous substrate obtained by compressing, shaping and sintering a refractory metal powder assembly. A step of providing a concave portion on the bottom surface of the high-melting-point metal porous substrate; and forming an electron-emitting substance mainly containing a compound of an alkaline earth metal oxide containing barium and alumina on the high-melting-point metal porous substrate. Impregnating and inserting the refractory metal porous substrate impregnated with the electron-emitting substance into the cup-shaped holder with the bottom face facing the inner bottom face of the cup-shaped holder; Fixing the porous substrate and the cup-shaped holder with a pair of welding electrodes, wherein a flat welding electrode is used as a first welding electrode on the electron emission surface side of the pair of welding electrodes; Shape hol The outer bottom surface side of the chromatography using non-planar welding electrodes respectively as a second welding electrode.

According to this configuration, the uniformity of the pressurization during welding is increased, and the current and voltage can be made constant.
Uniform and stable welding can be achieved, and the parallelism allowance between the welding electrodes can be reduced, so that the fixing work efficiency can be greatly improved.

(6) A cathode pellet in which a high-melting-point metal porous substrate is impregnated with a thermionic emission material, a cup-shaped holder fixed to the other surface of the high-melting-point metal porous substrate except for the electron emission surface, A holder having a cup-shaped holder and a head opposed to each other, and a sleeve fixed to a side wall of the cup-shaped holder. The cathode ray tube provided with the indirectly heated impregnated cathode structure fixed to the bottom surface opposite to the emission surface and having a minute gap in the fixed surface.

According to this configuration, since the high current density characteristic has a characteristic that can be maintained for a long time, such as tens of thousands of hours, and has a long-life indirectly heated impregnated cathode structure, a high luminance can be obtained. And a high-resolution and long-life cathode ray tube has been made possible.

It should be noted that the present invention is not limited to the above configuration, and various changes can be made without departing from the technical idea of the present invention.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples.

FIG. 1 is a schematic sectional view for explaining one embodiment of an indirectly heated impregnated cathode structure according to the present invention. In FIG. 1, reference numeral 1 denotes a porous metal substrate having a high melting point. The high melting point metal porous substrate 1 is granulated by adding a binder or the like to tungsten (W) metal powder, and is formed into a predetermined shape.
Sintered in a reducing atmosphere of about 900 ° C to a diameter of 1.0
It was formed to have a height of 0 mm and a height of 0.55 mm.

The high-melting-point metal porous substrate 1 has a concave portion 1c which forms a minute gap substantially at the center of the bottom surface 1b opposite to the thermionic emission surface 1a. The concave portion 1c has a height of 0.05 mm, an opening end diameter of 0.4 mm, and a bottom diameter of 0.3 mm.
It has a truncated cone shape of mm. The refractory metal porous substrate 1 is placed on the inner bottom surface 2a of a tantalum (Ta) cup-shaped holder 2 having a thickness of 0.05 mm, an inner diameter of 1.03 mm, an outer diameter of 1.13 mm and a height of 0.55 mm. 1b are faced to each other and fixed by welding. The two are fixed by welding using resistance welding.

The thermoelectron emission surface 1a protrudes from the tip 2c on the opening end side of the cup-shaped holder 2 by the welding and fixing. Reference numeral 3 denotes a thermionic emission material.
The ternary oxidation of barium (Ba), calcium (Ca), and aluminum (Al) is carried out by a known method in a reducing atmosphere from almost the entire surface of the refractory metal porous substrate 1 before being fixed to the cup-shaped holder 2. A compound (barium, calcium, aluminate) is melted and impregnated with a molten liquid. After completion of the impregnation, excess thermoelectron emitting material 3 is removed by stirring with hot water.

The high melting point metal porous substrate 1 containing the thermoelectron emitting material 3 is fixed to a cup-shaped holder 2 to form a cathode pellet 4. Reference numeral 5 denotes a sleeve.
Is made of tantalum (Ta), and the cathode pellet 4 is inserted into one end 5a of the cup-shaped holder 2 from the outer bottom surface 2b side so that the thermoelectron emission surface 1a is on the outside. Is welded and fixed to the side wall 5b by laser welding or resistance welding. SW3 indicates the welding site at that time. Reference numeral 6 denotes a heater which is inserted from the other end 5c side of the sleeve 5 and whose entire length is surrounded by the sleeve 5, and whose head 6a has a predetermined distance from the outer bottom surface 2b of the cup-shaped holder 2. It is arranged keeping the shape of the indirect heat. The heater 6, the sleeve 5 and the cathode pellet 4 constitute an indirectly heated impregnated cathode structure 7.

In this example, the diameter of the high-melting-point porous metal substrate 1 and the inner diameter of the cup-shaped holder 2 are substantially the same, but the diameter of the high-melting-point porous metal substrate 1 is made larger than the inner diameter of the cup-shaped holder 2. It may be reduced to about 0.2 mm.

FIG. 2 is a sectional view showing a state in which an object to be welded is arranged between a pair of welding electrodes in order to explain a manufacturing method of one embodiment of the indirectly heated impregnated cathode structure according to the present invention shown in FIG. 1 are given the same reference numerals.

In FIG. 2, the pair of first and second welding electrodes 21 and 22 have a combination of flat and convex surfaces 21a and 22a, respectively. On the flat welding electrode 21 having the facing surface 21a,
The cup-shaped holder 2 combined with the refractory metal porous substrate 1 containing the thermionic emission material 3 is placed so that the thermionic emission surface 1a faces the flat opposing surface 21a.

Next, in this state, the non-planar welding electrode 22 having the convex facing surface 22a, which is the second welding electrode disposed opposite to the planar welding electrode 21, is lowered as shown by an arrow 23. The cathode pellet 4 is formed by pressurizing and energizing to weld and fix the refractory metal porous substrate 1 containing thermionic emission material 3 and the cup-shaped holder 2 by welding.

Here, in this example, the flat welding electrode 21 as the first welding electrode was formed by processing a part of a tungsten round bar having a diameter of 12 mm into a flat surface. This electrode material is copper,
Molybdenum or the like may be used. The non-planar welding electrode 22, which is the second welding electrode, is made of a copper rod having a diameter of 6 mm using a facing surface 22.
a is a spherical surface having a radius of curvature of 5 mm. In this example, it was confirmed that the object could be achieved if the radius of curvature was 4 mm or more in this example. Further, the electrode material is not limited to copper, and may be, for example, tungsten, molybdenum, or the like.

The cathode pellet 4 thus formed
Is fixed to a sleeve 5 and a heater 6 is inserted to produce an indirectly heated impregnated cathode structure 7.

In the example shown in FIG. 2, the non-planar welding electrode 22 having a spherical opposing surface is used, so that the concave portion 1c of the minute gap existing between the refractory metal porous substrate 1 and the cup-shaped holder 2 is formed. Can be uniformly pressed at the opening end side, thereby performing welding while maintaining the contact between the bottom surfaces 1b and 2a better, so that the current and voltage during welding are constant. It enabled uniform, strong and stable welding.

Further, by using a combination of flat and non-planar welding electrodes, the degree of parallelism between the two electrodes required at the time of welding can be reduced, and the working efficiency can be greatly improved.

FIG. 3 shows the welding strength of the high melting point metal porous substrate and the cup-shaped holder and its fluctuation in comparison with the present invention and the prior art.
f, input power (voltage V × current A): 300 W, welding time: 3 ms.

Under this condition, the method of the present invention is the same as that of FIG. 2 described above, and the conventional method is that there is no concave portion 1c between the high melting point metal porous substrate 1 and the cup-shaped holder 2. The materials and dimensions were the same as in FIG. 2 except that a flat electrode was used for each of the pair of welding electrodes.

As is apparent from FIG. 3, the welding strength of 600 to 700 gf is obtained by the method of the present invention shown by a circle.
And little fluctuation. It is clear from the results of experiments by the present inventors that there is no practical problem if the welding strength is 400 gf or more in view of the product life.

On the other hand, in the case of the conventional method indicated by square marks, the welding strength fluctuates greatly from a minimum of 200 gf to a maximum of 750 gf. It clarifies what cannot be done.

FIGS. 4A to 4C are schematic cross-sectional views for explaining another embodiment of the indirectly heated impregnated cathode structure according to the present invention, and the same parts as those in FIGS. 1 and 2 are the same. The symbol is attached.

First, in the embodiment shown in FIG. 4A, the bottom surface 31b of the refractory metal porous substrate 31 opposite to the thermionic emission surface 31a is flat, while the inner bottom surface of the cup-shaped holder 32 is flat. A recess 32b forming a minute gap is provided substantially at the center of 32a. The dimensional shape of the concave portion 32b is substantially the same as the concave portion 1c of FIG. . Reference numeral 32c denotes a tip on the opening end side of the cup-shaped holder 32, 34 denotes a cathode pellet, and 37 denotes an indirectly heated impregnated cathode structure.

Next, in the embodiment shown in FIG. 4 (b), the refractory metal porous substrate 41 has an annular concave portion 41c substantially at the center of the bottom surface 41b opposite to the thermionic emission surface 41a. The inner bottom surface 42a of the cup-shaped holder 42 also has a concave portion 42b at a position facing the concave portion 41c. Also in this example, the thermoelectron emission surface 41a protrudes from the tip 42c on the opening end side of the cup-shaped holder 42. Reference numeral 44 denotes a cathode pellet, and reference numeral 47 denotes an indirectly heated impregnated cathode structure.

Further, in the embodiment shown in FIG.
In the embodiment shown in (1), the inner bottom surface 2a of the cup-shaped holder 2 is fixed by pressing and deforming along the concave portion 1c. This configuration can also be achieved by selecting the shape of the spherical surface of the non-planar electrode shown in FIG. 2, for example.
Can be brought closer to the refractory metal porous substrate 1 side.

In the above description, one or both of the high-melting-point metal porous substrate and the cup-shaped holder are provided with one concave portion, but it is needless to say that a plurality of concave portions may be provided.

FIG. 5 is a sectional view in the in-line direction illustrating a specific example of the entire structure of the cathode assembly when the indirectly heated impregnated cathode structure according to the present invention is mounted on a color cathode ray tube.
Although the illustration of the heater is omitted in the indirectly heated impregnated cathode structure, it has the configuration of the embodiment of FIG. 1 described above.

In FIG. 5, reference numeral 51 denotes three cylindrical cathode supports, 52 denotes one insulating substrate, and the insulating substrate 52 is formed by penetrating each of the cathode supports 51 at a predetermined interval and having one end thereof. The seal is fixed at 51a. The indirectly heated impregnated cathode structure 7, which is arranged coaxially with the cathode support 51, is fixed to one end 53a of a disk 53 at the opening end of the sleeve 5 opposite to the cathode pellet 4. The other end 5 of 53
3b is fixed at the end of the cathode support 51 opposite to the fixed end of the cathode support 51 with the insulating substrate 52. Reference numeral 54 denotes an entire cathode assembly including three indirectly heated impregnated cathode structures 7. This cathode assembly 54 is fixed together with other electrodes constituting the electron gun to an insulating support rod in a predetermined relationship. It constitutes an in-line type electron gun. The crosses in the figure indicate fixed points.

FIG. 6 is a side view showing an example of an electron gun assembly used for a color cathode ray tube on which the cathode assembly shown in FIG. 5 is mounted. 6, reference numeral 60 denotes a cathode assembly, 61 denotes a first electrode, 62 denotes a second electrode, 63 denotes a third electrode, 64 denotes a fourth electrode, 65 denotes a fifth electrode, 66 denotes a sixth electrode, and 67 denotes a seventh electrode. 68, a beading glass (insulating support rod); 69, a stem; 69a, a stem pin.

In the figure, the cathode assembly 60, the first electrode 61, the second electrode 62, the third electrode 63, the fourth electrode 64, the fifth electrode 65, the sixth electrode 66 and the seventh electrode 67 are a pair of beads. It is coaxially fixed with a loading glass 68.

The electron beam emitted from the cathode assembly 60 is applied to the first electrode 61, the second electrode 62, the third electrode 63, the fourth electrode 64, the fifth electrode 65, the sixth electrode 66, and the seventh electrode 67.
Then, the light is subjected to required acceleration and focusing, and is emitted from the seventh electrode 67 in the direction of the fluorescent screen. The stem pin 69a is a terminal for applying a voltage and an image signal required for predetermined electrodes constituting the electron gun.

FIG. 7 is a partial cross-sectional view of a shadow mask type color cathode ray tube for explaining one embodiment of a cathode ray tube having the indirectly heated impregnated cathode structure according to the present invention.
Is a panel, 72 is a neck, 73 is a funnel, 74 is a phosphor screen, 75 is a shadow mask having many electron beam passage holes, 76 is a mask frame, 77 is a magnetic shield,
78 is a shadow mask suspension mechanism, 79 is an electron gun that emits three electron beams Bc (center electron beam) and Bs (two side electron beams), DY is a deflection yoke that deflects the electron beam horizontally and vertically, MA is an external magnetic device such as a purity correction.

In the figure, a panel 71 having a fluorescent screen 74 on the inner surface and a funnel 73 are provided inside a bulb formed by the panel 71 and the funnel 73.
5 and a mask frame 76 to which the magnetic shield 77 and the like are fixed are mounted by a shadow mask suspension mechanism 78, and the panel 71 and the funnel 73 are welded and fixed with frit glass. Is vacuum sealed.

Electron beam B emitted from electron gun 79
c and Bs are deflected in two directions, horizontal and vertical, by a deflection yoke DY attached to a transition portion between the neck 72 and the funnel 73, and form a phosphor screen through an electron beam passage hole of a shadow mask 75 which is a color selection electrode. Phosphor screen 74 of predetermined color
To form an image.

The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention described in the appended claims.

[0059]

As described above, according to the present invention,
The presence of the minute gap in the fixing surface between the high melting point metal porous substrate and the cup-shaped holder makes it possible to improve the fixing strength of both and secure the reliability of the fixing.

In addition, the uniformity of pressurization during welding is increased, the current and voltage can be made constant, uniform and stable welding can be performed, and the parallelism tolerance between welding electrodes is reduced. The fixing work efficiency can be greatly improved.

Furthermore, when welding and fixing, thermionic emission material does not erupt violently, and as a result, the welding trace does not become a hole, and a good welding and fixing state is obtained. To provide a long-life indirectly heat impregnated cathode structure and a high-brightness, high-resolution, long-life cathode ray tube that can secure the structure and eliminate contamination around the cathode structure due to blowing of thermionic emission material from the welding hole. Can be done.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining one embodiment of an indirectly heated impregnated cathode structure of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a method of manufacturing the indirectly heated impregnated cathode structure of the present invention.

FIG. 3 is a diagram for explaining the welding strength of the indirectly heated impregnated cathode structure of the present invention.

FIG. 4 is a schematic cross-sectional view for explaining another embodiment of the indirectly heated impregnated cathode structure of the present invention.

FIG. 5 is an in-line direction cross-sectional view illustrating a specific overall configuration example of a cathode assembly including the indirectly heated impregnated cathode structure of the present invention.

6 is a side view showing an example of an electron gun assembly used for a color cathode ray tube on which the cathode assembly shown in FIG. 5 is mounted.

FIG. 7 is a partial cross-sectional view of a shadow mask type color cathode ray tube showing one embodiment of a cathode ray tube having the indirectly heated impregnated cathode structure of the present invention.

FIG. 8 is a schematic sectional view showing a conventional indirectly heated impregnated cathode structure.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 High-melting-point metal porous substrate 1c recess 2 cup-shaped holder 3 electron-emitting substance 4 cathode pellet 5 sleeve 6 heater 7 indirectly heated impregnated cathode structure

Continuing from the front page (72) Inventor Hiroshi Takakura 3350 Hayano Mobara-shi, Chiba Prefecture Hitachi Electronics Devices, Ltd. (72) Inventor Yukio Suzuki 3300 Hayano Mobara-shi, Chiba Display Group of Hitachi, Ltd. 72) Inventor Norihide Shibata 3300 Hayano, Mobara-shi, Chiba Prefecture, Hitachi, Ltd.Display Group (72) Inventor Shunji Saito 3300, Hayano, Mobara-shi, Chiba Prefecture, Hitachi, Ltd.Display Group, Hitachi, Ltd. Hikari 3300 Hayano, Mobara-shi, Chiba F-term (reference) 5C027 CC10 5C031 DD10 DD15 DD19 in Display Group, Hitachi, Ltd.

Claims (6)

[Claims] A cathode pellet comprising a refractory metal porous substrate impregnated with a thermionic emission material; a cup-shaped holder fixed to the other surface of the refractory metal porous substrate except for an electron emission surface; An indirectly heated impregnated cathode structure having a holder and a heater having its head opposed to each other, and a sleeve fixed to a side wall of the cup-shaped holder, wherein the cup-shaped holder has an inner bottom surface having the height. An indirectly-heated impregnated cathode structure fixed to a bottom surface of the porous metal base member opposite to the electron emission surface and having a minute gap in the fixed surface. 2. The apparatus according to claim 1, wherein the minute gap is formed by a concave portion of one or both of a bottom surface of the refractory metal porous substrate and an inner bottom surface of the cup-shaped holder. Hot impregnated cathode structure. 3. The indirectly-heated impregnated cathode structure according to claim 1, wherein the bottom surface of said cup-shaped holder has a substantially central portion protruding toward said refractory metal porous substrate. 4. An end of the cup-shaped holder on the opening end side surrounding the refractory metal porous substrate is receded from the electron emission surface of the refractory metal porous substrate. 1. An indirectly heated impregnated cathode structure. 5. A method for producing an indirectly heat impregnated cathode structure comprising impregnating an electron emitting material into a high melting point metal porous substrate obtained by compressing, shaping and sintering a high melting point metal powder assembly. Forming a concave portion on the bottom surface of the high-melting-point metal porous substrate, and impregnating the high-melting-point metal porous substrate with an electron-emitting substance mainly composed of a compound of an alkaline earth metal oxide containing barium and alumina. And inserting the inside of the cup-shaped holder with the bottom surface of the refractory metal porous substrate impregnated with the electron-emitting substance facing the inner bottom surface of the cup-shaped holder. Welding the base and the cup-shaped holder with a pair of welding electrodes, wherein a flat welding electrode is provided as a first welding electrode on the electron emission surface side of the pair of welding electrodes, and the cup-shaped Holder A method for producing an indirectly heated impregnated cathode structure, wherein a non-planar welding electrode is used as the second welding electrode on the outer bottom surface side. 6. A cathode ray tube comprising an indirectly heated impregnated cathode structure having a structure in which a refractory metal porous substrate is impregnated with a thermionic emission material, wherein the refractory metal porous substrate is provided with a thermionic emission material. An impregnated cathode pellet, a cup-shaped holder fixed to the other surface of the refractory metal porous substrate except for the electron emission surface, a heater in which the cup-shaped holder and its head are arranged to face each other, The cup-shaped holder has a side wall fixed to a side wall of the refractory metal porous substrate opposite to the electron emission surface, and a small gap is formed in the fixed surface. A cathode ray tube comprising an indirectly heated impregnated cathode structure having: