JP2002140998A - Electron gun and cathode-ray tube image receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress diffusion of electron radiating material evaporating from a cathode substrate, prevent temperature decrease of the cathode substrate, and decrease number of component items. SOLUTION: This electron gun comprises a cathode substrate 14 having the electron radiating material and an outer sleeve 17 as a cylindrical holder for holding the cathode substrate 14. The inside 171 and the outside 172 of the outer sleeve 17 are made of different kinds of metal materials. The electron gun is mounted on the inside of a neck part of a cathode-ray tube bulb to provide the cathode-ray tube image receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube receiver such as a television receiver or a computer display, and more particularly to a structure of an electron gun mounted on a cathode ray tube.

[0002]

2. Description of the Related Art In a cathode ray tube receiver, an electron beam emitted from an electron gun is deflected up, down, left and right by a deflection magnetic field of a deflection yoke, thereby scanning a spot of the electron beam on a phosphor screen on an inner surface of a panel. The image is displayed.

In an electron gun serving as an emission source of an electron beam, a cathode substrate having an electron emitting material is heated to a predetermined temperature (operating temperature) to emit electrons (thermoelectrons) therefrom.
An electron beam is emitted toward the phosphor screen by controlling the amount, moving speed, and beam trajectory of the electrons with a plurality of grid electrodes.

The cathode base of the electron gun for emitting the electron beam has a structure (impregnated cathode) in which a porous metal base is impregnated with an electron-emitting substance made of an oxide such as Ba (barium). Here, the operating temperature of the impregnated cathode is about 200 degrees higher than that of the oxide cathode. During operation, Ba evaporated from a cathode disk made of a sintered body such as tungsten diffuses into the inner wall surface of the cathode assembly. If it spreads and diffuses to the vicinity of the heater below the cathode, there is a problem that leakage occurs between the cathode and the heater and between the cathode and the focus lead.

Therefore, conventionally, from the viewpoint of preventing Ba from diffusing in the cathode structure, a sleeve shield made of nickel / chromium material is inserted inside a cylindrical sleeve holding the cathode base, and the surface of the sleeve is inserted into the sleeve. Is considered to have been subjected to a blackening treatment for applying a chromium oxide film to the surface.

FIG. 5 is an enlarged view of a main part of a conventional electron gun. The cathode assembly 12 includes a cathode base 14 serving as an electron emission source.
A heater 15 for heating the cathode base 14, an inner sleeve 16 containing the heater 15, an outer sleeve 17 disposed outside the inner sleeve 16, and a sleeve holder for holding the sleeves 16, 17 18 is provided.

The cathode substrate 14 is made of a porous metal substrate obtained by sintering a reducing metal such as W (tungsten).
This is an impregnated cathode substrate impregnated with a composite oxide such as a (barium), Ca (potassium), or Al (aluminum) as an electron-emitting substance.

[0008] The cathode base 14 is housed in a cup 19, and the cup 19 is held in such a manner as to be fitted to the tip of the inner sleeve 16. In the cathode assembly 12, a shield 21 is disposed inside the outer sleeve 17 in a state of shielding the outer sleeve 17. This shield 21 is formed in a cylindrical shape as a whole.

The distal end side of the shield 21 is arranged in a state of being close to the inner peripheral surface of the outer sleeve 17 with a slight gap of, for example, about 20 to 30 μm. Further, the shield 21 and the outer sleeve 17 are integrally joined by welding (laser welding or the like) parts close to each other.

The shield 21 is, for example, an outer sleeve 1
It is made of the same metal material as No. 7, that is, a heat-resistant alloy such as Kovar or nickel / chromium. On the surface of the shield 21, an oxide film 21A for suppressing reduction and diffusion of the electron-emitting substance is formed.

The oxide film 21A is, for example, a shield 21
Is composed of Kovar, the shield 21
When the shield 21 is made of a chromium alloy (such as nickel / chromium), the shield 21 is formed by heating the shield 21 in a wet hydrogen gas flow.

In the case where the cathode assembly 12 is formed using the shield 21 having the oxide film 21A on the surface as described above, the inner peripheral surface of the outer shield 17 is shielded by the shield 21 over almost the entire area. The electron emitting material BaO evaporated from the cathode base 14 is transferred to the outer sleeve 17.
Can be prevented from adhering to the surface.

Further, even if the electron-emitting substance BaO evaporated from the cathode base 14 adheres to the shield 21,
An oxide film 21 is formed between a reducing substance (silicon or the like) added to the material and an electron emitting substance BaO attached to the shield surface.
Since A intervenes as a barrier, it is possible to suppress the diffusion and reduction of the electron-emitting substance BaO on the surface of the shield 21 and the generation of a leak current associated therewith.

[0014]

However, such an electron gun has the following problems. That is, the cathode structure of the electron gun is formed by combining a plurality of sleeves and shields, and there is a problem that the structure of the cathode structure is complicated. In addition, the number of components is increased, and equipment for welding the sleeve and the shield is required, which causes a reduction in process yield.

Further, an oxide film is formed on the entire surface of the shield attached to prevent the diffusion of Ba, and the heat of the heater for heating the cathode substrate is transmitted from the shield via the sleeve through the oxide film. The temperature of the cathode substrate is lowered. As a result, it is not possible to maintain an accurate operating temperature of the cathode base, which causes a decrease in display quality.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems. That is, the present invention provides an electron gun including a cathode base having an electron emitting substance and a cylindrical holder for holding the cathode base, wherein the inside and outside of the cylindrical holder are made of different kinds of metal materials. It is. Also, the present invention is a cathode ray tube receiver in which this electron gun is provided in the neck of a cathode ray tube bulb.

According to the present invention, since the cylindrical holder for holding the cathode base is made of different kinds of metal materials on the inside and outside, the inside of the cylindrical holder is kept even under the same processing conditions. Only the blackening process can be performed.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view including a partially broken cross section of a cathode ray tube bulb to which the electron gun according to the present embodiment is applied. In FIG. 1, a cathode ray tube bulb 1 includes a panel section 2,
It comprises a funnel 3 and a neck 4. On the inner surface of the panel section 2, a phosphor screen formed by arranging red, green, and blue phosphors in a pattern is formed. Also,
The panel section 2 and the funnel section 3 are joined via a frit seal section 5.

The funnel 3 has a substantially funnel shape as a whole, and a neck 4 extends integrally from the funnel 3. An electron gun 6 serving as an emission source of an electron beam is incorporated in the neck portion 4. Further, a color selection mechanism 7 that selectively passes an electron beam from the electron gun 6 and performs color selection is mounted inside the panel unit 2.

In the cathode ray tube having the above structure, the electron gun 6
Is deflected vertically and horizontally by a deflection magnetic field of a deflection yoke (not shown). As a result, a spot of the electron beam is applied to the fluorescent screen on the inner surface of the panel unit 2 in a spot-like manner via the color selection mechanism 7, and the beam spot is vertically and horizontally scanned on the fluorescent screen.

As a result, a desired image (color image, monochrome image, etc.) is displayed on the screen of the cathode ray tube. Such a cathode ray tube reproduces (displays) an image on the phosphor screen inside the panel unit 2.
Together with various accessories necessary for the operation, a cathode ray tube receiver such as a television receiver or a computer display is constituted.

FIG. 2 is a schematic side view showing an overall image of the electron gun according to this embodiment. The illustrated electron gun 6 mainly includes a cathode assembly 8 that emits electrons, and the cathode assembly 8.
A grid electrode unit 9 for controlling the amount, moving speed, orbit, and the like of electrons (beams) emitted from the semiconductor device; and a pair of bead glasses 10 for integrally holding these in an electrically insulated state.
The external power supply voltage is applied to the cathode assembly 8 and the grid electrode 9.
And a stem portion 11 for supplying the same.

FIG. 3 is a half sectional view showing the overall structure of the cathode assembly 8. In FIG. 3, the cathode assembly 8 includes:
Three cathode structures 12 corresponding to red, green and blue colors are incorporated. These cathode structures 12 are integrally fixed to a common ceramic disk 13.

Each of the cathode assemblies 12 includes a cathode base 14 serving as an electron emission source, a heater 15 for heating the cathode base 14, and an inner sleeve 1 containing the heater 15 therein.
6, an outer sleeve 17 disposed outside the inner sleeve 16, and a sleeve holder 18 for holding the sleeves 16, 17.

The cathode substrate 14 is made of, for example, a porous metal substrate obtained by sintering a reducing metal such as W (tungsten).
This is an impregnated cathode substrate impregnated with a composite oxide such as a (barium), Ca (potassium), or Al (aluminum) as an electron-emitting substance. In the vicinity of the cathode base 14,
Two grid electrodes G1 and G2, which are components of the grid electrode section 9, are arranged. In addition, the cathode substrate 1
4 is accommodated in a cup 19, and the cup 19 is held in such a manner as to be fitted to the tip of the inner sleeve 16.

FIG. 4 is an enlarged view of a main part of the electron gun according to this embodiment. In FIG. 4, the inner sleeve 16, the outer sleeve 17, and the sleeve holder 18 each have a cylindrical structure (cylindrical holder) having a circular cross section, and these are arranged substantially concentrically outside the heater 14. Among these, the inner sleeve 16 is supported by the outer sleeve 17 by a plurality of (for example, three) strap-shaped ribbons (elongated thin metal pieces) 20. Each ribbon 20
Is connected to the rear end of the inner sleeve 16, and the other end is connected to the front end of the outer sleeve 17.

In this embodiment, the outer sleeve 17
Are formed of different types of metal materials on the inner side 171 and the outer side 172. For example, a nickel / chrome material is used as the metal material of the inner side 171, and a Kovar material is used as the metal material of the outer side 172. That is, the outer sleeve 1
7 is formed using a clad material in which a nickel / chromium material and a Kovar material are overlapped. When this clad material is processed into the shape of the outer sleeve 17, the inner 171 is a nickel / chromium material and the outer 172 is a kovar material. Material.

Further, before assembling the outer sleeve 17 into the cathode structure 12, the outer sleeve 17 is heated in a hydrogen atmosphere supplied through a wetting device and subjected to a blackening treatment.
Here, since the outer sleeve 17 uses a nickel / chrome material for the inner side 171 and a Kovar material for the outer side 172, only the nickel / chromium material on the inner side 171 is oxidized in the blackening process, and only the surface of the inner side 171 is exposed. An oxide film 17A is formed.

As described above, the cathode assembly 12 is formed by using the outer sleeve 17 having the oxide film 17A only on the surface of the inner side 171.
In the electron gun configured as above, the cathode substrate 1
Even when the electron-emitting substance BaO evaporated from 4 adheres to the outer sleeve 17, the reduction and diffusion of the electron-emitting substance BaO on the surface of the outer sleeve 17 are suppressed by the oxide film 17A. As a result, it is possible to effectively prevent the electron-emitting substance BaO attached to the outer sleeve 17 from spreading over the entire surface of the sleeve, thereby suppressing unnecessary electron emission from the rear end of the outer sleeve 17 and generation of a leak current associated with the emission. It becomes possible.

Further, in the outer sleeve 17 of the present embodiment, only the inner side 171 of the outer sleeve 17 is formed by the oxide film 1 by the blackening process.
Since 7A is formed and no oxide film is formed on the outer side 172, it is difficult for heat from the heater 15 to escape to the outside. Therefore, even if the outer sleeve 17 has been subjected to the blackening process, the operating temperature due to the heating of the cathode base 14 can be accurately maintained.

Also, as described above, the inner side 1 of the outer sleeve 17 is
By performing the blackening process on 71, components such as a shield which has been separately subjected to a blackening process are not required, the number of components of the cathode assembly 12 can be reduced, and a process such as laser welding between the outer sleeve and the shield is unnecessary. Thus, the manufacturing process of the cathode assembly 12 can be simplified.

In the embodiment described above, nickel / chromium material is used for the inner side 171 and kovar material is used for the outer side 172 as the cladding material constituting the outer sleeve 17, but the inner side 171 is made of a metal material which is easily blackened. , Outside 1
If a metal material that is not easily blackened is used for the metal layer 72, any other metal material can be used.

In the above embodiment, the outer sleeve 17
Was heated in a wet hydrogen atmosphere to perform blackening treatment on the inner side 171. However, other methods (for example, a method of applying and fixing chromium oxide powder) may be used.

[0034]

As described above, the present invention has the following effects. That is, since the inside and outside of the cylindrical holder are made of different types of metal materials,
Under the same conditions, only the inside is blackened, and the cylindrical holder suppresses the reduction and diffusion of the electron-emitting substance evaporating from the cathode substrate, but without releasing the heat of the cylindrical holder by the heater to the outside. I will be able to live. As a result, it is possible to prevent the temperature of the cathode base from lowering and to exhibit sufficient performance as an electron gun. Further, the number of parts of the electron gun can be reduced, and the manufacturing process can be simplified. By using this electron gun for a cathode ray tube receiver, it is possible to improve the reliability and the production yield.

[Brief description of the drawings]

FIG. 1 is a perspective view including a partially broken cross section of a cathode ray tube bulb to which an electron gun according to an embodiment is applied.

FIG. 2 is a schematic side view showing an overall image of the electron gun according to the embodiment.

FIG. 3 is a half sectional view showing the entire structure of the cathode assembly.

FIG. 4 is an enlarged view of a main part of the electron gun according to the embodiment.

FIG. 5 is an enlarged view of a main part of a conventional electron gun.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cathode ray tube bulb, 2 ... Panel part, 3 ... Funnel part, 4 ... Neck part, 6 ... Electron gun, 8 ... Cathode assembly part, 12
... Cathode assembly, 14 ... Cathode base, 15 ... Heater, 16 ... Inner sleeve, 17 ... Outer sleeve, 17A ... Oxide film, 18 ...
Sleeve holder, 20 ... ribbon, 171 ... inside, 172
… Outside

Claims (4)

[Claims] 1. An electron gun comprising: a cathode base having an electron emitting substance; and a cylindrical holder for holding the cathode base, wherein the cylindrical holder is made of different types of metal materials inside and outside. An electron gun. 2. The cylindrical holder according to claim 1, wherein only the inner metal material is blackened.
The described electron gun. 3. The electron gun according to claim 1, wherein the metal material inside the cylindrical holder is made of nickel / chrome and the metal material outside is made of Kovar. 4. A cathode ray tube receiver having a cathode ray tube bulb and an electron gun provided in a neck portion of the cathode ray tube bulb, wherein the electron gun comprises: a cathode base having an electron emitting material; and a cathode base. A cathode ray tube receiver comprising: a cylindrical holder to be held; and a cylindrical holder made of different types of metal materials inside and outside.