JPH1074465A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the deterioration of the modulation efficiency of an electrode beam path and the heating of an electrode resulting from eddy current generated in an electron gun metal electrode portion in a high frequency magnetic field by using nonmetal material such as ceramic for an electron gun electrode portion in a cathode-ray tube. SOLUTION: By using nonmetal material for an electron gun electrode portion 1a, the occurrence of eddy current resulting from the high frequency magnetic field 9 of a convergence yoke 8 and the like is suppressed, no deterioration of modulation efficiency of an electron beam path is allowed even in a high frequency modulation area, and also the heating of the electrode portion 1a is suppressed. Since the deterioration of the modulation efficiency of the electron beam path by an alternating current magnetic field is little even in a high frequency modulation area exceeding 100kHz, no excess power is required for a deflection yoke, a convergence yoke, a velocity modulation coil, and the like even in the cathode-ray tube of a high grade television and the like in which high frequency modulation is conducted so that the breakage of a cathode-ray tube neck portion resulting from the heating of the electrode portion can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube used as a television or a computer display.

[0002]

2. Description of the Related Art Conventionally, in a cathode ray tube, an electron beam trajectory is generally modulated by an alternating magnetic field generated by a deflection yoke, a convergence yoke, a velocity modulation coil, and the like until an electron beam emitted from a cathode reaches a screen. I do.

A deflection yoke is generally inserted into a funnel cone portion of a cathode ray tube, and deflects the trajectory of the electron beam by an alternating magnetic field generated by the deflection yoke, thereby scanning the cathode ray tube fluorescent screen with the electron beam. I have.

A convergence yoke is generally inserted outside the neck of a cathode ray tube, and corrects raster distortion by modulating the trajectory of an electron beam with an AC magnetic field generated by the convergence yoke.

[0005] The velocity modulation coil is generally inserted outside the neck of the cathode ray tube, and modulates the scanning speed of the electron beam with an alternating magnetic field generated by the velocity modulation coil to form a high-luminance portion on the phosphor screen. It has the function of preventing the image from protruding into the low luminance area and sharpening the image.

An electrode of an electron gun exists between a coil for modulating the orbit of the electron beam with a magnetic field at a high frequency and the electron beam. As a material for an electrode of an electron gun, a metal material having high conductivity such as stainless steel is generally used for the purpose of applying a voltage to form an electron lens. The area resistance is, for example, about 2 mΩ / □ in the case of SUS304 stainless steel having a plate thickness of 0.4 mm.

FIG. 6 shows an example of the structure of an electron gun portion of a projection type monochrome cathode ray tube as a conventional cathode ray tube. The anode electrode 1 is made of stainless steel. In this example, the center of the magnetic field of the convergence yoke 8 is located at a position 7 mm from the front end of the anode electrode 1 on the phosphor screen side, and most of the AC magnetic field 9 generated by the convergence yoke 8 passes through the anode electrode 1. The deflection yoke 16 is inserted into the funnel cone part, and a part of the AC magnetic field 17 generated by the deflection yoke 16 passes through the cylinder 15 that shields the anode electrode 1 and the getter. Speed modulation coil 1
Reference numeral 8 denotes an AC magnetic field generated by the velocity modulation coil 18 and disposed between the front anode 3 and the focusing electrode 2.
Most of 9 passes through the pre-stage anode electrode 3 and the focusing electrode 2.

[0008]

When an AC magnetic field is applied through these metal electrodes, an eddy current is generated in the metal electrode portions. In addition, the higher the frequency of the AC magnetic field, the greater the eddy current loss, so that the effect of the magnetic field to modulate the electron beam trajectory in the high-frequency modulation region decreases.

In the conventional example shown in FIG. 6, for example, an eddy current is generated in the anode electrode 1 by the AC magnetic field 9 generated by the convergence yoke 8, and the convergence yoke 8 reduces the electron beam orbit modulation effect.

The eddy current loss may cause the electrode to generate heat and break the neck tube. If the distance between the source of the AC magnetic field and the metal electrode of the electron gun is designed to be large in order to prevent the loss of the AC magnetic field and the heat generation of the electrodes, the distance between the electron beam focusing lens and the phosphor screen will inevitably be increased. Is increased, and the magnification of the electronic lens is increased. In particular, in an image display device having a high deflection frequency and a wide signal band, such as a high definition television, there is a problem that the loss of the AC magnetic field is large, which causes a problem in practical use.

An object of the present invention is to provide a cathode ray tube in which the loss of an AC magnetic field and the heat generation of the electrodes are reduced in order to solve the conventional problems.

[0012]

In order to achieve the above object, a cathode ray tube according to the present invention comprises a glass panel having a phosphor screen on the inner surface, a glass funnel connected to a rear portion thereof, and an electron gun therein. In a cathode ray tube having a neck portion, a nonmetallic material is used for an electrode portion of an electron gun.

In the above-mentioned cathode ray tube, the non-metallic material of the electron gun electrode portion has a sheet resistance of 20 mΩ / □ to 100 GΩ.
/ □ is preferably a resistance material.

In the above-mentioned cathode ray tube, it is preferable that the nonmetallic material of the electrode portion of the electron gun is ceramics. Materials such as conductive alumina ceramics, conductive titania-based ceramics, and silicon carbide ceramics can be used as the ceramic material. The preferred thickness of the ceramic electron gun electrode is 0.5 m.
m and 2.0 mm or less. 0.5mm thick
When the thickness is less than 2.0 mm, the material becomes brittle and the strength tends to be impractical. On the other hand, when the thickness exceeds 2.0 mm, it is necessary to make the electron lens formed therein small, so that an accurate electron beam trajectory is formed. In addition, the cost tends to increase, and the workability tends to deteriorate.

[0015] With the above configuration, generation of an eddy current due to a high-frequency magnetic field generated by a coil for modulating the electron beam trajectory with a high frequency magnetic field can be suppressed, and the modulation efficiency of the electron beam trajectory can be reduced even in a high-frequency modulation range. Deterioration does not occur, and heat generation at the electrode portion can be suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electron gun in a projection type monochrome cathode ray tube as a cathode ray tube according to one embodiment of the present invention.

In FIG. 1, the anode electrode 1a has an outer diameter 22
It is manufactured by a high-resistance ceramic cylinder (made of alumina ceramics) having a thickness of 1 mm, a thickness of 1 mm, and a specific resistance of 1 kΩ · cm, and has a sheet resistance of 10 kΩ / □.
A stainless steel focusing electrode 2 having an inner diameter of 15 mm is located inside the anode electrode 1a, and an electron gun composed of these components is inserted inside a neck tube having an outer diameter of 29.1 mm. Reference numeral 7 denotes a cathode ray tube neck.

In this case, the anode electrode 1a is a metal part such as a bracket 10 for fixing an electrode having a flange outer diameter of 22 mm and a contact spring 11 for applying an anode potential from a conductive layer applied to the inner surface of the neck of the cathode ray tube. The conductive adhesive 12 is used for this fixation. For this, an adhesive such as frit glass in which silver particles are dispersed can be used.

Even if the adhesive itself does not have conductivity, a conductive coating can be applied to the surface to achieve electrical conduction.

Since the position of the anode electrode 1a is the same as the conventional one, most of the AC magnetic field 9 generated by the convergence yoke 8 passes through the anode electrode 1a, but the anode electrode 1a is made of a resistance material. Because
The generation of the eddy current due to the AC magnetic field 9 is suppressed, the modulation efficiency of the electron beam trajectory is not degraded even in the high frequency modulation region, and the heat generation at the anode electrode 1a is also suppressed.

The resistance material used for the electrode material of the present invention needs to have a certain resistance value or more in order to realize the above-mentioned effects, and at the same time, a resistance value small enough not to cause charging of the electrode itself. Therefore, there is a certain range of restriction on the resistance value.

If the area resistance of the resistive material used for the electrode material of the present invention is less than 20 mΩ / □, the above effects cannot be sufficiently obtained.

If the sheet resistance is greater than 100 GΩ / □, the electric field becomes unstable due to charging, and the electron lens effect changes with time, so that the shape of the electron beam spot on the phosphor screen changes with time. Adversely affect.

Therefore, the range of the sheet resistance of these materials should be 20 mΩ / □ to 100 GΩ / □.

FIG. 2 shows the results of comparing the frequency response characteristics of the convergence magnetic field of the cathode ray tube according to this embodiment with those of the conventional cathode ray tube. 100kHz for convergence yoke
The deflection width of the electron beam on the phosphor screen due to the convergence yoke magnetic field when the sinusoidal current is given, that is, the deflection efficiency of the electron beam, is 137 compared with the conventional cathode ray tube.
%.

On the other hand, the amount of heat Q generated on the electrode by the high-frequency magnetic field can be expressed by the following equation (Equation 1), where φ is the magnetic field strength, f is the frequency, and R is the area resistance value of the electrode.

[0028]

(Equation 1)

The resistance value of the conventional metal electrode portion is about 2 mΩ / □, and the resistance value of the electrode portion in the present embodiment is 10 kΩ / □. Calorific value was 5 × 1 compared to the example using the conventional metal electrode.
It drops to ^0-4 %.

In this embodiment, the anode electrode is made of a high-resistance ceramic, but other resistance materials, for example, a glass resistor in which porous glass is impregnated with carbon by a gas phase method, or the like is used. The same effect can be obtained. In the case of a glass tube, since the molding accuracy is higher than that of ceramics, cutting work for improving the shape accuracy is not required, which is advantageous in cost.

FIG. 5 shows another embodiment of the present invention. In FIG. 5, the anode electrode 1b has a sheet resistance of 10 kΩ /
The ceramic cylinder 13 provided with the layer 14 of the resistance material of □ is used.

As the resistance material, a glass glaze thick film resistance in which a conductive material such as ruthenium oxide is dispersed in a glass paste can be used.

As a coating method, a dipping method in which the anode electrode is immersed in a paste-like resistance agent and pulled up, or a method in which a resistance layer is formed directly on the inner wall of the anode electrode by a dispenser or printing are considered. In the dip method, the resistance material is easily applied to the inner surface of the ceramic cylinder, so that mass productivity is high. In the dispenser method or the printing method, the resistive material can be applied uniformly, and the quality is stable.

Also in the present embodiment, similar to the first embodiment,
The anode electrode needs to be fixed to a metal part such as a bracket 10 for fixing the electrode or a contact spring 11 for applying an anode potential from a conductive layer applied to the inner surface of the neck of the cathode ray tube. For example, a conductive adhesive 12 in which silver particles are dispersed in an adhesive can be used.

Also in this example, since a resistive material is used for the anode electrode 1b, the eddy current generated in the anode electrode 1b by the AC magnetic field 8 generated by the convergence yoke 8 is suppressed, and the loss of the AC magnetic field is reduced. .

In this embodiment, the resistance layer 14 is provided by applying a resistance agent whose resistance value is relatively easy to adjust on the inner surface of the ceramic cylinder 13 which has been machined with high precision by cutting. It is easy to adjust to a desired resistance value. The resistance value can be easily adjusted by changing the ratio of a conductive substance such as ruthenium oxide.

In this embodiment, ceramics is used as the structure for forming the resistance layer, but it is also possible to use an insulating material such as a glass tube. When a glass tube is used, since the molding accuracy is higher than that of ceramics, cutting work for improving the shape accuracy is not required, which is advantageous in cost.

When the electron lens is distorted due to the electrification of the portion of the glass tube or the ceramic cylinder not covered with the resistance layer and affects the electron beam trajectory, the resistive agent is also applied to the portion other than the inner surface of the glass tube or the ceramic cylinder. Is applied, distortion of the electronic lens can be avoided.

In this embodiment, a glass glaze thick film resistor is used as the resistive layer. However, the resistive film may be formed by depositing a thin metal film such as chromium or aluminum on the inner surface of the cylinder. Is also possible. By using this method, the firing step required for the glass glaze thick film resistance method can be omitted, and the resistance layer forming step is simplified.

In the embodiment of the present invention, the anode electrode 1a is fixed to the bracket 10 or the contact spring 11 by using the conductive adhesive 12, but as shown in FIG. It is also possible to fix this anode electrode 1a by a caulking method of pressing a nail.
Also, as shown in FIG. 4, it is possible to fix the anode electrode 1a by pressing a spring provided on the bracket portion 10 against the anode electrode. By using these methods, the assembling process of the electron gun can be simplified.

As an embodiment of the present invention, the case where the present invention is applied to a unipotential type electron gun having an electrode structure in which a focusing electrode is arranged inside an anode electrode has been described. The same can be applied to a unipotential type electron gun in which the anode electrode and the aperture of the focusing electrode are arranged to face each other.

As an embodiment of the present invention, the case where the present invention is applied to a unipotential type electron gun has been described. However, the present invention naturally relates to an electron gun having another structure, for example, a bipotential type electron gun. Can be similarly implemented.

In the embodiment of the present invention, the case where the present invention is used for an anode electrode has been described. However, the present invention is not limited to a conventional control electrode, an accelerating electrode, a focusing electrode, and a conventional cylinder such as a cylinder for shielding a getter. The same applies to an electron gun component manufactured using a metal material.

In this case, as an effect, it is possible to prevent the modulation efficiency of the electron beam trajectory from being deteriorated due to the AC magnetic field passing through these electron gun parts. For example, when the present invention is used for a cylinder that shields a getter, it is possible to prevent the modulation efficiency of the electron beam trajectory from being deteriorated by the AC magnetic field of the deflection yoke and the convergence yoke, and to be used for the control electrode, the acceleration electrode, and the focusing electrode. In this case, it is possible to prevent the modulation efficiency of the electron beam trajectory from being deteriorated by the AC magnetic field of the velocity modulation coil.

In the above description, the case where the present invention is applied to a monochrome cathode ray tube is described. However, the same effect can be obtained by using a color cathode ray tube.

[0046]

As described above, according to the present invention, 100
Even in a high-frequency modulation range exceeding kHz, there is little deterioration in the modulation efficiency of the electron beam orbit due to the AC magnetic field.
Even in a cathode ray tube that performs high-frequency modulation such as a high-definition television, an excessive power is not required for a deflection yoke, a convergence yoke, a speed modulation coil, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structural example of an electron gun portion of a monochrome cathode ray tube which is an embodiment of the cathode ray tube of the present invention.

FIG. 2 is a diagram showing frequency response characteristics of a convergence magnetic field of the electron gun according to the embodiment of the present invention and a conventional electron gun.

FIG. 3 is a cross-sectional view showing an example of a structure of an electrode fixing method using a caulking method according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a structural example of an electrode fixing method using a spring according to an embodiment of the present invention.

FIG. 5 is a sectional view showing another example of the structure of the electron gun portion of the monochrome cathode ray tube according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a structural example of an electron gun portion of a monochrome cathode ray tube as a conventional cathode ray tube.

[Explanation of symbols]

Reference Signs List 1 anode electrode 1a anode electrode using high-resistance ceramic 1b anode electrode using ceramic cylinder provided with resistive film 2 focusing electrode 3 pre-stage anode electrode 4 acceleration electrode 5 control electrode 6 cathode 7 cathode ray tube neck 8 convergence yoke 9 convergence Yoke magnetic field 10 Anode electrode fixing bracket 11 Contact spring 12 Conductive adhesive 13 Ceramic cylinder 14 Resistive material layer 15 Getter shielding cylinder 16 Deflection yoke 17 Deflection yoke magnetic field 18 Speed modulation coil 19 Speed modulation coil magnetic field

Claims (4)

[Claims] 1. A cathode ray tube comprising a glass panel having a fluorescent screen on an inner surface, a glass funnel connected to a rear portion thereof, and a neck having an electron gun therein, wherein a non-metallic electrode is provided on an electron gun electrode. A cathode ray tube using a material. 2. The cathode ray tube according to claim 1, wherein the nonmetallic material of the electron gun electrode portion is a resistance material having a sheet resistance of 20 mΩ / □ to 100 GΩ / □. 3. The cathode ray tube according to claim 1, wherein the non-metallic material of the electrode portion of the electron gun is a ceramic. 4. The cathode ray tube according to claim 1, wherein the thickness of the electrode portion of the ceramic electron gun is in a range of 0.5 mm or more and 2.0 mm or less.