JP2984309B2 - Cathode support structure and method of manufacturing the same - Google Patents

Description

The present invention relates to a cathode support structure for supporting a cathode used in a color picture tube or the like, and a method for manufacturing the same.

(Prior Art) In recent years, there has been a demand for the development of a color picture tube, an ultra-high-frequency picture tube, etc. in which the number of scanning lines is increased and the resolution is improved.
Further, it is desired that the luminance of a projection tube be improved.
To meet these demands, it is necessary to greatly increase the density of electrons emitted from the cathode.

However, the impregnated cathode has a higher current density than the oxide cathode, and has been used for electron tubes such as image pickup tubes, traveling wave tubes, and klystrons.However, in the field of color picture tubes, only special applications are limited. Was.

Such an impregnated cathode assembly is conventionally configured as follows.

That is, a heater is disposed inside a cathode sleeve made of Mo or Ta, and a cup having a cathode impregnated with an emitter is fixed to one end of the cathode sleeve. Further, the cathode sleeve is fixed to a holder coaxially arranged outside the cathode sleeve by three straps.

However, as a drawback of the impregnated cathode, the operating temperature is about 200 ° C higher than that of the oxide cathode, and accordingly the heater temperature is also high, rising to about 1250 ° C during rated operation, resulting in the thermal deformation of the heater and the The breakdown voltage between the cathodes was deteriorated. Conventionally, several attempts have been made to increase the thermal efficiency of the heater and to lower the temperature of the heater.

For example, Japanese Patent Publication No. 63-66391 discloses a method for manufacturing a deep-drawn cathode shaft having a thermal black surface at least inside. That is, providing a metal plate at least one surface of which is made of a metal selected from the group consisting of molybdenum, nickel, iron, tungsten and copper or an alloy containing at least one metal selected from the group of metals,
A layer of aluminum or a layer substantially consisting of aluminum is applied to the surface to a thickness of 1 to several μm, and the metal plate is heated at a temperature of 750 to 800 ° C. in a substantially non-reactive atmosphere. To convert the deposited layer to an aluminum compound,
A shaft is formed from a metal plate by a deep drawing method, and the shaft is heat-treated in a wet hydrogen atmosphere at a humidity in the range of 950 to 1200 ° C. until almost all of the aluminum compound is converted to aluminum oxide. A characteristic black layer is obtained.

On the other hand, Japanese Patent Application No.
In 241851, TaOx (X = 1 to 1) is applied to the inner surface of the cathode support.
An impregnated cathode structure having a blackened layer formed in 2) has been proposed. That is, a T with an outer diameter of 1.6 mm, a thickness of 25 μm, and a length of 1 m
a The outside of the sleeve is placed in an Ar atmosphere, and air is fed into the Ta sleeve at a flow rate of 0.1 / min. In this state, heating is performed at 610 ° C. ± 10 ° C. for 5 minutes by a surrounding heater. The inner surface oxidized sleeve thus formed is cut to a length of 4.5 mm by a laser, and then subjected to vacuum heat treatment at 1300 ° C. for 1 hour to remove gas to produce an inner surface blackened sleeve.

(Problems to be Solved by the Invention) In the conventional example, in order to form a thermal blackening film on the inner surface of the cathode support structure, two high-temperature treatments of 600 ° C to 800 ° C and 950 ° C to 1400 ° C are performed. It was necessary and there was a problem in industrial mass production.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode support structure that increases the thermal efficiency of a heater, lowers the heater temperature, and is industrially productive.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, in a cathode support structure having a built-in heater and having a cathode on the top, an amorphous metal oxide, amorphous hydroxide Using one of a metal object and a mixture of both, a metal,
Alternatively, a layer containing any one of metal oxides, carbides, and nitrides is formed. Further, the production of the cathode support structure is a method for producing a cathode support structure including a step of applying a suspension containing a metal alkoxide compound to the surface of the cathode support structure and a step of heat-treating the cathode support structure.

Methoxide M (OCH ₃ ) as alkoxide compound
_n (M: aetal), ethoxide M (OC ₂ H ₅ ) _n , n-propoxide M (OnC ₃ H ₇ ) _n , isopropoxide M (O
_{· I-C 3 H 7)} n may be any ones like.
Those which are easily dissolved in water-soluble lower alcohols such as methanol, ethanol and propanol at room temperature are easy to handle industrially.

(Operation) According to the present invention, since the heat radiation rate of the porous ceramic layer is large, the porous ceramic layer absorbs the heat of the heater and conducts it to the cathode.
If the cathode temperature is the same, the heater temperature can be set lower. Furthermore, since this layer is porous, it has a large specific surface area and is densely formed on the cathode support structure, thereby suppressing generation of gas, or having an action of adsorbing gas, and is easily poisoned by gas. The cathode can be protected from toxic gases.

Further, when the metal alkoxide compound according to the present invention is used, sintering can be performed at 200 ° C. or lower, and industrial mass productivity is significantly improved.

(Example) Hereinafter, an example of the cathode support structure of the present invention will be described in detail with reference to the drawings.

First, a method for blackening the cathode support structure made of Ta will be described. A Ta sleeve having an outer diameter of 1.6 mm, a thickness of 25 μm, and a length of 1 m is prepared. Silicon containing zircon (ZrSiO ₄ ) as a filler having the following composition on the inner surface of the Ta sleeve, and an alkoxide compound of zirconia; For example, Si (OC ₂ H ₅ ) ₄ + Z
A suspension of r (OC ₄ H ₁ ) ₄ was applied.

Composition zircon 500 gr alkoxide compound of silicon and zirconia 100 gr isopropyl alcohol 400 gr By heating in an atmosphere, a porous ceramic layer having a thickness of about 3 μm was obtained. That is, the alkoxide compound of silicon and zirconia applied to the Ta sleeve is hydrolyzed by atmospheric moisture in an atmosphere of about 150 ° C. As a result, a film is formed by a polycondensation reaction between the alkoxides, and A mixed layer of an amorphous layer containing silicon and zirconia metal oxide and a metal hydroxide was formed. The alkoxide compound forms a film if the temperature is 70 ° C. or higher.
In this example, the temperature was set to 150 ° C. for further stabilization. According to experiments by the present inventors, it was confirmed that a sufficiently porous ceramic layer was formed in an atmosphere of 200 ° C. or lower.

In the above-described example, the suspension is heated after being applied. However, if the suspension is applied while being heated at about 150 ° C. for shortening the manufacturing time, the subsequent heat treatment step can be omitted. Further, since the alkoxide compound of silicon and zirconia has good absorption characteristics of electromagnetic rays in the infrared region, when forming a film,
Rather than in an atmosphere at 0 ° C. or lower, the surface of the Ta-made sleeve on which the alkoxide compound of silicon and zirconia is applied, for example, after applying a suspension containing the alkoxide compound of silicon and zirconia while irradiating with infrared rays, at room temperature It was also confirmed that film formation was sufficiently performed. Further, after coating, infrared rays can be irradiated.

When the Ta sleeve having the porous ceramic layer on the inner surface is cut to a length of 4.5 mm by laser in this way, an inner surface heat radiation type cathode support structure is obtained.

One embodiment of an impregnated cathode structure using the inner surface heat radiation type cathode support structure will be described with reference to FIG.

That is, a cathode substrate (1) in which porous tungsten obtained by sintering a tungsten powder having a particle diameter of 3 to 10 μm and an electron-emitting substance composed of BaO, CaO, and Al ₂ O ₃ is impregnated with a Ta cup (2) ) Having a ceramic layer (4) sintered at a low temperature after welding through a brazing material (3) such as Ru-Mo.
After being inserted into the top of the cathode support structure (5), it is fixed by welding at a welding point (6). On the outer periphery of the bottom of the cathode support structure (5), three wall thicknesses of 0.3 mm welded at welding points (7).
05mm, 0.7mm wide strap made of Ta ribbon (8)
Is provided, and the other end of the strap (8) is
It is welded to the shoulder of a cylindrical holder (9) made by press-forming a 0.125 mm thick Fe-Ni-Co alloy plate at a welding point (10). A heater (11) is provided inside the Ta cathode support structure.

According to the present invention, the same cathode temperature (for example, rated 96
The heater temperature at 0 ° C. b) could be reduced by about 125 ° C. as compared with the case where a cathode support structure having no blackening layer on the inner surface was used. In addition, the cathode temperature was forced (rated 960
In contrast to 10 ° C. b, a withstand pressure failure between the heater and the cathode support structure was not observed in the life test at 1030 ° C. b). The present invention, in which the porous ceramic layer is formed on the inner surface in this way, can reduce the heater temperature by about 125 ° C, and as a result, it is possible to prevent the occurrence of the withstand voltage defect between the heater and the cathode and the occurrence of the thermal deformation defect of the heater. It became.

Further, by making the inner surface of the Ta-made cathode support structure porous, the gas release rate of the cathode support structure is 1100 ° C., and after 30 minutes, the present invention is 2 × 10 ⁻⁵ Torr cc / sec mg, which is smaller than that of the conventional one. 2.6 × 10 ^-5 Torr cc Ta cathode support structure without blackening layer on the surface
Outgassing is suppressed at / secmg. This is because, since a thermally stable ceramic layer was provided on the surface of the cathode support structure, which is likely to generate an unstable gas at a very high temperature, the release of gas from the cathode support structure was suppressed.
This is because the specific surface area by the so-called BET method, which is calculated from the absorption of low-pressure nitrogen gas, is approximately 50 times as large as that of the conventional Ta surface, so that the gas generated in the vicinity can be efficiently adsorbed.

In the present embodiment, zircon was used as the filler, but the gist of the present invention is not limited to this.For example, a blackening pigment made of another metal oxide such as cobalt oxide, chromium oxide, iron oxide, manganese oxide or the like as the filler. If used, the thermal emissivity can be further improved, and the thermal efficiency of the heater can be further improved.
Further, similar effects were obtained even when silicon carbide, boron carbide, tungsten carbide, or the like was used as a carbide as a filler. This is because the thermal conductivity of the carbide is 0.130 c of Ta
silicon carbide: 1.0, boron carbide: 0.6
5. Tungsten carbide: 0.7, which is large, making it easier to transfer the heat of the heater to the cathode.

On the other hand, in the present embodiment, a compound of silicon and zirconia was described as the metal alkoxide compound, but the gist of the invention is not limited to this, as with the filler. Can do things.

Although the above description has been given of the embodiment using the impregnated type cathode, it is clear that the same effect can be obtained even when applied to other cathodes such as an oxide cathode having a lower operating temperature. . Further, in the embodiment, the sleeve-shaped cathode support structure is used. However, the shape is not limited to this embodiment, and it can be applied to a deep drawing cathode shaft disclosed in, for example, Japanese Patent Publication No. 63-66391. Needless to say.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, a heater temperature can be drastically reduced by the manufacturing method rich in industrial mass production, and it becomes possible to eliminate the withstand pressure defect of a heater.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing one embodiment of an impregnated cathode structure using the cathode support structure of the present invention. 1 ... Cathode, 4 ... Porous ceramic layer 5 ... Cathode support structure, 11 ... Heater

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 29/04 H01J 1/20 H01J 9/04 H01J 1/26

Claims (6)

(57) [Claims] 1. A cathode supporting structure having a heater at least one end of which has a cathode at one end thereof, wherein at least an inner surface of the cathode structure has an amorphous metal oxide and an amorphous hydroxide as a binder. A cathode support structure, comprising a layer using at least one of a metal and an oxide, carbide, or nitride of a metal and at least one of a metal and a mixture thereof as a filler. 2. The cathode support structure according to claim 1, wherein said layer is a porous ceramic layer. 3. A method for manufacturing a cathode support structure having a cathode at one end, the method including a step of applying a suspension containing a metal alkoxide compound to at least an inner surface of the cathode support structure. And a step of heat-treating the cathode support structure. 4. The method according to claim 3, wherein the heating step includes a heating step at 200 ° C. or lower. 5. The method according to claim 3, wherein the metal alkoxide compound is one selected from the group consisting of silicon, titanium, aluminum and zirconium, or a mixture thereof. 6. The filler in the suspension is a group of three kinds of oxides of silicon carbide, manganese oxide, chromium oxide, iron oxide, cobalt oxide, copper oxide, zirconium, zirconium, tungsten and zircon, zirconium and tungsten. 4. The method for producing a cathode support structure according to claim 3, wherein the method is one or a mixture selected from the group consisting of: