KR20020066858A - Electron gun for color cathode ray tube - Google Patents

Abstract

PURPOSE: An electron gun for color CRT is provided to obtain balanced focusing force of three electron beams by improving the shape of aperture of focus electrode into a peanut shape. CONSTITUTION: An electron gun comprises a plurality of electron beam radiating elements; a triode unit constituted by a plurality of electrodes for adjusting the amount of electron beam; a focus electrode(23) and an anode electrode for forming a main lens for focusing the electron beam to a screen, wherein the focus electrode and the anode electrode have opposed surfaces having apertures for passage of three electron beams including a central electron beam(4b) and side electron beams(4a,4c). The aperture of the focus electrode has a vertical interval gradually decreasing as it goes from the side electron beam passage position toward the central electron beam. The vertical interval of the aperture of the focus electrode at the central electron beam side is at least larger than the vertical interval of the aperture of the anode electrode at the central electron beam side.

Description

Electron Gun for Color Cathode Ray Tube {Electron Gun For Color Cathode Ray Tube}

The present invention relates to a color cathode ray tube, and more particularly, to an electron gun for a color cathode ray tube that optimizes the shape of a central electron beam on a screen by changing a shape of an opening electrode in a focus electrode.

A color cathode ray tube is a device that implements a screen by hitting a screen by combining three electron beams emitted from an electron gun. 1 schematically shows a configuration of a general color cathode ray tube.

Referring to FIG. 1, the color cathode ray tube is combined with a panel 1 coated with blue (B), green (G), and red (R) color bodies, and coupled to an inner surface of the panel 1 to sort colors. A shadow mask 2 having a function, a funnel 3 forming the appearance of a cathode ray tube, an electron gun 5 for emitting and controlling an electron beam 4, and a neck tube 6 into which the electron gun 5 is inserted ) And a deflection yoke 7 for deflecting the electron beam emitted from the electron gun.

2A and 2B show schematic and cross-sectional views of one type of inline electron gun used in a conventional color cathode ray tube.

Referring to FIGS. 2A and 2B, the conventional inline type electron gun includes a cathode 8 radiating hot electrons, a first electrode 9 and a second electrode 9 controlling / accelerating hot electrons radiated from the cathode 8. ) And a third electrode 11, a fourth electrode 12, a focus electrode 13, and an anode forming an electrostatic focusing lens for focusing the electron beam 4 on the fluorescent film 16 coated on the panel. The electrodes 14 are arranged at regular intervals, and the electrodes are fixed with insulating bead glass 15.

Hereinafter, a process in which the electron beam starting from the cathode reaches the screen will be described.

The hot electrons radiated from the cathode 8 by the heating of a heater (not shown) inserted into the cathode 8 are controlled by the first electrode 9 and accelerated by the second electrode 10. do. A voltage of about 1000 V or less is applied to the second electrode 10 and the fourth electrode 12, and about 20 to 40 of a voltage applied to the anode electrode 13 is applied to the third electrode 11 and the focus electrode 13. The corresponding voltage of% is applied. The electron beam 4 is formed by the electrostatic lens formed between the second electrode 10 and the third electrode 11 and the electrostatic lens formed by the third electrode 11, the fourth electrode 12, and the focus electrode 13. The incident angle incident on this main lens is determined.

A high voltage of about 20000 V or more is applied to the anode electrode 14, which corresponds to about 20 to 40% of the anode electrode 14 to the focus electrode 13 facing the anode electrode 14 at a distance of about 0.8 mm or more. When a voltage is applied, a main electrostatic focusing lens is formed between the two electrodes. The electron beam 4 passing through the main lens is caused by the influence of the magnetic field formed by the strength of the current applied to the deflection yoke 7 which simultaneously surrounds the lower end of the outer cover of the funnel 3 and the upper end of the neck tube 6. The path is determined. The electron beam 4 traveling along this path passes through the shadow mask 2 provided in front of the fluorescent film 16 and collides with the fluorescent film 16 to emit light.

As described above, the hot electrons radiated from the cathode 8 are focused on the screen by the electrostatic focusing lens and formed on the screen. At this time, the sharpness of the spot of the electron beam 4 on the screen depends on the following three components.

Where D _x is an enlarged component of the crossover point by the magnification of the electrostatic focusing lens, D _sa is an electron beam dispersion component due to the spherical aberration of the main lens, and D _sc is an electron beam dispersion component due to the space charge effect. .

Among them, spherical aberration has a great influence on the focus characteristic of the electron gun. An effective large-diameter electron gun is used to reduce spherical aberration and to improve resolution. The opening electrode 13a of the focus electrode 13 and the opening electrode 14a of the anode electrode 14 actually have a structure in which the openings face each other.

The focus electrode 13 includes a cap-shaped focus opening electrode 13a having a common opening having a race track shape, and a focus inner electrode 13b installed inside the focus opening electrode 13a and electrically connected thereto. The anode electrode 14 which is opposed to 13 and has a spacing of 0.8 to 1.3 mm in the tube axis direction is provided inside the cap-shaped anode opening electrode 14a having a common opening in the form of a dumbbell, and inside the anode opening electrode 14a. It consists of an anode inner electrode 14b electrically connected. The focus inner electrode and the anode inner electrode are also called electrostatic field control electrodes.

When the focus inner electrode 13b and the anode inner electrode 14b have substantially the same dimensions, the vertical openings of the anode opening electrode 14a are generally used to focus the electron beam 4 in the vertical direction. It is to be designed to be smaller than the vertical spacing of openings. In addition, the opening vertical spacing at the position of the center electron beam 4b of the anode opening electrode 14a is designed to be smaller than the opening vertical spacing at the position of the outer electron beams 4a and 4c, so that the center electron beam 4b and the outer electron beams 4a and 4c are not. Even focusing power can be obtained. In addition, the outer electron beams 4a and 4c have a difference in the focusing force in the central electron beam direction and the opposite focusing force relative to the center of the outer electron beam due to the asymmetry of the passage path.

4 is a projection view in which the focus opening electrode 13a and the anode opening electrode 14a are overlaid, and the anode opening electrode 14a is indicated by a dotted line for the purpose of classification. The horizontal end of the focus opening electrode 13a and the horizontal end of the anode opening electrode 14a generally coincide to obtain the maximum diameter, but the vertical gap of the opening is smaller than the focus opening electrode 13a of the anode opening electrode 14a. The horizontal focusing and diverging force by the opening electrodes 13a and 14a is closely related to the vertical spacing of the opening electrodes.

If the vertical spacing of the anode opening electrode 14a is made smaller than the vertical spacing of the focus opening electrode 13a, the divergence force in the vertical direction is increased, and the inflow from the opposing focus opening electrode 13a is weakened, so that the anode inner electrode 14b. The divergence in the horizontal direction is weakened.

The electron gun 5 of the prior art can be designed to properly focus on the screen in the horizontal and vertical directions, but the center axis and the anode opening electrode 14a of the outer electron beam passing portion of the focus opening electrode 13a having different curvature radii. Since the distance from the center axis of the outer electron beam passing through is different from the central axis, it is not equipped with a means for adjusting the focusing force by adjusting the distance from the opening electrodes to the electron beam at an arbitrary angle.

Due to this rotationally asymmetrical focusing force, the outer electron beam produces some distortion in the screen. If the electron beam is deflected to the periphery of the screen by the deflection yoke without being optimized at the center of the screen, the error component is enlarged and displayed, which in turn causes further degradation of the resolution at the periphery of the screen.

On the other hand, the dumbbell-shaped structure for equalizing the focusing force of the central electron beam 4b and the outer electron beams 4a and 4c causes some distortion of the central electron beam on the screen. This is because the divergence of the central electron beam in the diagonal direction at the anode opening electrode position is smaller than that of the vertical direction, so that the central electron beam has an accurate image in the horizontal and vertical directions on the screen, but is overfocused in the diagonal direction of the electron beam. ) Is generated.

5 is a simulation result of the shape of the central electron beam in the screen by the conventional electron gun. This shape causes an error component to be enlarged and displayed as the electron beam is deflected to the periphery of the screen, and thus becomes a factor to further reduce the resolution at the periphery of the screen.

The present invention has been made to solve the above-described problems of the prior art, the center beam side vertical spacing of the focusing opening electrode is narrower than the vertical beam side vertical spacing, but larger than the center beam side vertical spacing of the anode opening electrode to center the center electron beam It is an object of the present invention to provide an electron gun for color cathode ray tubes in which three electron beams have a balanced focusing force in each direction.

1 is a schematic cross-sectional view of a conventional color cathode ray tube.

2A and 2B are schematic diagrams and cross-sectional views schematically showing an electron gun of a conventional color cathode ray tube.

3 is a perspective view showing a focus electrode and an anode electrode of a conventional electron gun;

4 is a projection view simultaneously showing an opening electrode of a conventional electron gun main lens unit;

5 is an electron beam shape diagram on a screen by a conventional electron gun.

6A and 6B are plan views of a focus opening electrode and an anode opening electrode according to the present invention;

7 is an electron beam shape view on a screen with an electron gun according to the present invention;

** Explanation of symbols for main parts of drawings **

1: Panel 2: Shadow Mask

3: funnel 4: electron beam

5: electron gun 6: neck tube

7: deflection yoke 8: cathode

9: first electrode 10: second electrode

11: third electrode 12: fourth electrode

13,23: focus electrode 14, 24: anode electrode

13a and 23a: focus opening electrode 14a and 24a: anode opening electrode

In order to achieve the above object, the present invention includes a tripolar portion for adjusting the radiation amount of the electron beam emitted from the heater, and a focus electrode and an anode electrode forming a main lens for focusing the electron beam on the screen, the focus electrode and the anode In the opposite surface of the electrode is made of an opening through which a plurality of electron beams pass in common, the electron gun for a color cathode ray tube having an electrostatic field control electrode retracted a certain distance from the opening,

The opening of the focus electrode is gradually reduced as the vertical distance from the outer beam passing position toward the center beam side, wherein the vertical distance on the center beam side is formed to be at least greater than the vertical distance of the center beam side opening of the anode electrode. Provide an electron gun.

The structure of this invention is demonstrated in detail, referring an accompanying drawing. For reference, prior to the description of the present invention, in order to avoid duplication of description, the same reference numerals as those of the prior art will be referred to.

6A and 6B show a plan view of an anode electrode and a focus opening electrode of a color cathode ray tube electron gun according to the present invention.

The shape of the anode opening electrode 24 illustrated in FIG. 6B is a dumbbell shape in which the diameter of the ball partially covering the outer electron beam is larger than the vertical width of the opening electrode at the center electron beam position, which is consistent with the prior art, and thus, the detailed description thereof will be omitted. .

FIG. 6A illustrates a focus opening electrode 23 according to the present invention, and the outer side is semicircle to balance the focusing force in each direction with respect to the center of the center electron beam, and is perpendicular to the opening electrode on the inline axis. The distance between the center electron beam center and the outer electron beam is increased to a certain distance to form a peanut (peanut) form.

Hereinafter, the operation of the electron beam according to the structure of the present invention will be described in more detail.

When a high voltage of about 20000 to 35000V is applied to the anode electrode 24 and a voltage of about 5000 to 10000V is applied to the focus electrode 23, an electrostatic lens is formed between the two electrodes. At this time, the focus opening electrode 23a and the anode opening electrode 24a have a smaller focusing diameter in the vertical direction than the horizontal diameter and thus have a stronger focusing force in the vertical direction.

The weakened electric field penetrated through the focus opening electrode 23a and the anode opening electrode 24a has a similar level of horizontal focusing force and vertical focusing force by the focus inner electrode 23b and the anode inner electrode 24b. .

In addition, the two outer electron beams 4a and 4c receive a force directed to the central electron beam 4b by an electric field formed in the common opening of the focus opening electrode 13a and the anode opening electrode 14a, and receive the central electron beam on the screen. Gather towards.

The movement speed of the electron beam 4 in the electric field moves faster in the anode electrode 24 having a high potential, and thus the time for diverging in the anode electrode 24 is shorter than the time focused in the focus electrode 23. Therefore, the focusing action by the focus electrode 23 is strongly received rather than the diverging action by the anode electrode 24.

The vertical spacing of the electrodes through which the central electron beam of the focus opening electrode 23a passes is configured to be larger than the vertical spacing of the electrodes through which the central electron beam of the anode opening electrode 24a shown in FIG. 6B passes. Since the pinnut-shaped focus opening electrode 23a encloses the central electron beam less than the conventional focus opening electrode 13 (see FIG. 4) in the form of a race track, the focusing electrode 23a of the center opening beam 23b is positioned at the focus opening electrode 23a position. A weaker focusing effect is possible on the diagonal line (about 45 ° of the electron beam cross section).

Therefore, the halo phenomenon in the diagonal direction of the center electron beam generated in the conventional electron gun can be eliminated. That is, the focusing force in each direction can be made almost equal with respect to the center of the center electron beam. By doing so, the central electron beam 4b is uniformly focused in a circular or oval shape on the screen and improves the resolution throughout the screen.

7 shows the shape of the central electron beam on the screen of the computer simulation results of the electron gun according to the present invention.

As shown in FIG. 7, the central electron beam 4b has a nearly rotationally symmetrical focusing force at the center of the screen. Since the degree of focusing with respect to the center electron beam 4b is rotationally symmetrical by the electron gun structure of the present invention, when the center electron beam 4b is deflected to the periphery of the screen by the deflection yoke, the shape change due to the difference in focusing force You do not suffer. This improves resolution by forming small, distinct beam spots across the screen.

The present invention improves the shape of the opening of the focusing opening electrode used to realize the improved central electron beam characteristics on the screen in the form of a peanut, thereby sharpening the electron beam shape formed on the screen by balancing the focusing power in each direction with respect to the central electron beam. In this way, an electron gun that can cope with high definition and wide angle of CRT can be obtained.

Claims (1)

A three-pole portion consisting of a plurality of electron-spinning means for emitting an electron beam, a plurality of electrodes for adjusting the radiation amount of the electron beam, a focus electrode and an anode electrode forming a main lens for focusing the electron beam on a screen, In the opposing surface of the electrodes for the lens is formed of three electron beam common passage opening, the electron gun for a color cathode ray tube having an electrostatic field control electrode which is located at a predetermined distance from the opening into the electrode, The opening of the focus electrode is gradually reduced as the vertical distance from the outer beam passing position toward the center beam side, wherein the vertical distance on the center beam side is formed to be at least greater than the vertical distance of the center beam side opening of the anode electrode. Electron gun.