JPH05242833A - Color picture tube - Google Patents

Abstract

PURPOSE:To suppress an eddy current caused by an interlinkage of a deflecting magnetic field so as to improve the degradation of convergence by providing a conductive coat on an insulative getter supporting table substrate so as to increase the electric resistance of a getter supporting table. CONSTITUTION:The outside of a getter supporting table substrate 32 made of an insulator such as a ceramic is formed by means of a non-magnetic metal such as Al and graphite or a coat 33 coated by a non-magnetic and conductive substance. The thinner film thickness of the coat 33 in a thus constituted getter supporting table 31 is more effective, and is normally made to be 0.05mm or less, but if it is not conductive the supporting table 31 is unfavorably charged up resulting in an unstable potential state. Accordingly, an eddy current caused when a horizontal deflecting magnetic field interlinks the supporting table can be suppressed so as to prevent the displacement of electron beams 12 to 14. Therefore the degradation of convergence can be improved, so that the degradation of picture quality, such as color drift or the degradation of resolution, can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube,
In particular, it relates to the structure of the rod that supports the getter.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a general color picture tube. A vacuum container is composed of a panel 1 and a funnel 2, a fluorescent film 3 is formed on the inner surface of the panel 1, and a funnel 2 is formed. An electron gun 4 for emitting an electron beam is sealed on the opposite side of the fluorescent film 3. Further, a getter support rod 5 is attached to the tip of the electron gun 4 toward the fluorescent film side, and a donut-shaped getter container 6 is fixed to the tip of the getter support rod 5. Getter container 6
The inside contains a getter agent for increasing the degree of vacuum in the vacuum container. Further, outside the funnel 2 of the vacuum container, a deflection yoke 7 for displaying an image by scanning the electron beam emitted from the electron gun 4 vertically and horizontally is mounted.

The getter container 6 contains barium as a main component, and an alloy of aluminum and nickel in addition to the main component. After the vacuum container is evacuated to a vacuum, high frequency heating is performed to evaporate Ba therein. Then, a thin film is formed on the inner surface of the funnel, and this thin film adsorbs a small amount of gas in the vacuum container, so that a higher vacuum can be maintained.

[0004]

In the conventional color picture tube, as shown in FIG. 3, the getter container 6 is held by the getter supporting rod 5. Since the getter support rod 5 is in the deflection magnetic field as is clear from the figure, the material having magnetism disturbs the deflection magnetic field, and therefore must be non-magnetic. Therefore, non-magnetic stainless steel is usually used as the material for the getter supporting rod.

FIG. 4A shows a state in which the horizontal deflection magnetic field passes through the getter supporting rod, and is a view seen from the phosphor screen. In FIG. 4 (a), 5 represents a cross section of the getter supporting rod, and 3 which is emitted from the electron gun.
The electron beams 12, 13, 14 of the book are near the support rod,
The horizontal deflection magnetic field 11 passes through the entire cross section including the getter supporting rod and the electron beam. The horizontal deflection magnetic field 11 is
It is set to have a temporally varying magnetic field strength that moves the electron beams 12, 13, 14 to the right,
In the case of normal television display, the frequency is 15.
It is 75 KHz. When it is used as a display monitor, the frequency becomes high, and it becomes 31.5 KHz to 64.
It has become very high frequency of KHz or higher.

When the magnetic field strength fluctuates at a high frequency, an eddy current is also generated in the direction that hinders the change of the magnetic field in the paramagnetic getter supporting rod, and as a result, the horizontal deflection magnetic field is canceled in the vicinity of the getter supporting rod. A magnetic field is generated in the direction. Figure 4
(B) shows the situation, and an induced magnetic field 21 is generated from the getter supporting rod 5 by the eddy current generated inside the supporting rod. Due to the presence of this magnetic field 21, a force is applied to the electron beams 12, 13 and 14 passing in the vicinity thereof in the vector directions as shown in the figure.

Therefore, when there is no disturbance of the magnetic field due to the getter supporting rod, the electron beams 12, 13, 14 which should coincide with each other on the phosphor screen of the color picture tube, as shown in FIG. That is, the closer to the getter supporting rod 5, the more the deviation of the electron beams 12, 13 and 14 occurs, and the convergence is deteriorated, which causes the image quality deterioration such as the color deviation and the resolution deterioration.

[0008]

According to the present invention, a vacuum container is provided with at least a fluorescent screen, an electron gun, a getter supporting rod and a getter container, and a deflection yoke for deflecting an electron beam is provided outside the vacuum container. In the mounted color picture tube, the getter supporting rod is characterized by being made of a material having high electric resistance.

Specifically, the getter supporting rod has a structure in which a conductive coating is provided on the surface of an insulator, or is composed of a ceramic containing a conductive substance.

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the vicinity of the getter supporting rod of the first embodiment of the color picture tube of the present invention as seen from the phosphor screen side. The getter supporting rod 31 is formed by a film 33 in which the outside of a getter supporting rod base 32 made of an insulating material such as ceramic is coated with a nonmagnetic metal such as aluminum or graphite or a nonmagnetic conductive material. Since what is important here is to suppress the eddy current due to the interlinking of the horizontal deflection magnetic field, the thinner the film is, the more effective it is, and usually 0.05 mm or less is desirable. It should be noted that if the getter supporting rod is formed of only an insulator and is not electrically conductive, the getter supporting rod is charged up, resulting in an extremely unstable potential state, which is not preferable.

FIG. 2 is a sectional view of the vicinity of the getter supporting rod of the second embodiment of the color picture tube of the present invention. The getter support rod 41 uses a conductive ceramic containing a conductive substance as a component. Also in this case, the resistance value is higher than that of a simple metal, and the eddy current due to the interlinkage of the horizontal deflection magnetic field can be significantly suppressed.

[0012]

As described above, according to the present invention, in the color picture tube, by increasing the electric resistance of the getter supporting rod, the eddy current generated when the horizontal deflection magnetic field links the getter supporting rod is significantly suppressed. However, it has an effect of improving the deterioration of the convergence at the lower center of the phosphor screen, which has been a problem in the past. The eddy current due to the horizontal deflection magnetic field increases as the frequency of the deflection magnetic field increases, and the deterioration of convergence also increases.
The effect is more significant in a double speed television such as a DTV or a display monitor having a higher display density and a higher deflection frequency.

[Brief description of drawings]

FIG. 1 is a sectional view of the vicinity of a getter supporting rod according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the vicinity of a getter supporting rod according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional color picture tube.

4A and 4B are diagrams showing a horizontal deflection magnetic field and an induced magnetic field in the vicinity of a getter supporting rod.

FIG. 5 is a diagram showing a convergence pattern on a fluorescent film.

[Explanation of symbols]

 1 panel 2 funnel 3 fluorescent film 4 electron gun 5, 31, 41 getter supporting rod 6 getter container 7 deflection yoke 11 horizontal deflection magnetic field 12, 13, 14 electron beam 21 induced magnetic field 32 getter supporting rod substrate 33 coating

Claims (3)

[Claims] 1. A color picture tube in which at least a fluorescent screen, an electron gun, a getter supporting rod and a getter container are provided in a vacuum container, and a deflection yoke for deflecting an electron beam is mounted outside the vacuum container, The color picture tube, wherein the getter supporting rod is made of a material having high electric resistance. 2. The color picture tube according to claim 1, wherein the getter support rod has a structure in which a conductive film is formed on a surface of an insulator. 3. The color picture tube according to claim 1, wherein the getter supporting rod is made of a ceramic containing a conductive material.