KR20090057535A - Electron gun assembly for cathode ray tube and cathode ray tube having the same - Google Patents

Abstract

An electron gun for cathode ray tube and a cathode-ray tube equipped with the same are provided to improve a control electrode, a focus electrode and the structure of an acceleration electrode and to improve the focus level of the electronic beam. The control electrode(34) comprises an aperture. The first rim part(44) of the focusing electrode(38) is positioned at one side for the acceleration electrode from the electronic beam projection face of the focusing electrode to the acceleration electrode to the first height. The second rim part(46) of the acceleration electrode(40) is positioned at one side for the focusing electrode from the electronic beam entering face of the acceleration electrode to the focusing electrode to the second height. The first height is large than the second height. The width of the first rim part is smaller than the width of the second rim part.

Description

Electron gun for cathode ray tube and cathode ray tube equipped with electron gun {ELECTRON GUN ASSEMBLY FOR CATHODE RAY TUBE AND CATHODE RAY TUBE HAVING THE SAME}

The present invention relates to a cathode ray tube, and more particularly, to a cathode ray tube electron gun having an improved structure of a control electrode, a focusing electrode, and an acceleration electrode of an electron gun in order to improve a focus level of an electron beam in an optical deflection cathode tube having an enlarged deflection angle. It is about.

In general, an electron gun for a color cathode ray tube is composed of three cathodes generating three stem electron beams, and a control electrode, a screen electrode, a focusing electrode, and an acceleration electrode which are provided at a distance from each other. The control electrode, screen electrode, focusing electrode and acceleration electrode have three apertures through which three stem electron beams pass.

The electron beam emitted from the cathode forms a cross-over point in the triode consisting of the cathode, the control electrode and the screen electrode, and the electron beam forming the water point is formed by a pre-focus lens formed between the screen electrode and the focusing electrode. It is pre-focused and finally focused in the main-focus lens formed between the focusing electrode and the accelerating electrode to form a spot on the fluorescent screen.

In addition, the electron beam emitted from the electron gun is deflected in the horizontal and vertical directions by the deflection magnetic field in which the deflection yoke is generated to scan the fluorescent screen. This causes the electron beam to emit red, green and blue phosphors constituting the fluorescent screen to display a predetermined image. The deflection yoke is mounted on the outer periphery of the funnel and generates a horizontal deflection magnetic field and a vertical deflection magnetic field.

In the color cathode ray tube, a so-called self-convergence method in which a horizontal deflection magnetic field is formed in a pincushion type and a vertical deflection magnetic field is formed in a barrel type in order to match (convergence) three-beam electron beams in the entire fluorescent screen. Is applying.

However, due to the self-convergence magnetic field, the three-stem electron beam passing through the deflection magnetic field is diverged along the horizontal direction of the screen, and is focused along the vertical direction of the screen. Therefore, the spots formed on the periphery of the fluorescent screen are distorted in the horizontal direction to increase the horizontal size, and over-focus in the vertical direction to generate low luminance hollow, thereby increasing the vertical size.

This deterioration of focus level occurs more remarkably in an optical deflecting cathode ray tube in which the deflection angle is enlarged to reduce the overall length, and causes a deterioration in image quality of the periphery of the screen, especially the corner.

An object of the present invention is to provide an electron gun for a cathode ray tube and a cathode ray tube provided with the electron gun, which can realize excellent image quality by improving the focus level of the periphery of a screen in an optical deflecting cathode ray tube having an enlarged deflection angle.

An electron gun for a cathode ray tube according to an embodiment of the present invention includes a plurality of cathodes emitting electrons, and a control electrode, a screen electrode, a focusing electrode, and an accelerating electrode sequentially positioned at a distance from each other from the plurality of cathodes. The control electrode forms three apertures whose vertical width is greater than the horizontal width, and the focusing electrode forms a first rim positioned at a first height toward the acceleration electrode from the electron beam exit surface of the focusing electrode on one side facing the acceleration electrode. In addition, the acceleration electrode forms a second rim positioned at a second height toward the focusing electrode from the electron beam incident surface of the acceleration electrode on one side facing the focusing electrode. The first height is greater than the second height, and the width of the first rim portion is formed smaller than the width of the second rim portion.

The horizontal width of the control electrode aperture may be formed corresponding to the threshold size of the cathode load. The focusing electrode may receive a fixed focus voltage. The focusing electrode may include a first focusing electrode, a second focusing electrode, and a third focusing electrode positioned at a distance from each other, and the third focusing electrode may form a first rim.

The first focusing electrode may be formed in a plate shape, and the second focusing electrode and the third focusing electrode may be formed in a cylindrical shape having a bottom surface on the side where the electron beam enters and the side where the electron beam exits.

Cathode ray tube according to an embodiment of the present invention is a vacuum tube including a face panel and a funnel and neck, a fluorescent screen formed on the inner surface of the face panel, a deflection yoke installed on the outer periphery of the funnel, and located inside the neck And an electron gun having a plurality of cathodes emitting electrons, and a control electrode, a screen electrode, a focusing electrode, and an acceleration electrode sequentially positioned at a distance from each other from the plurality of cathodes. The control electrode forms three apertures whose vertical width is greater than the horizontal width, and the focusing electrode forms a first rim positioned at a first height toward the acceleration electrode from the electron beam exit surface of the focusing electrode on one side facing the acceleration electrode. In addition, the acceleration electrode forms a second rim positioned at a second height toward the focusing electrode from the electron beam incident surface of the acceleration electrode on one side facing the focusing electrode. The width of the first rim is smaller than the width of the second rim, and the first height is greater than the second height.

The deflection yoke can realize a deflection angle of 120 °.

In the cathode ray tube of the present invention, the total length of the cathode ray tube can be reduced by expanding the deflection angle and shortening the length of the electron gun. In addition, the shape of the control electrode aperture provided in the electron gun and the shape of the main-focus lens formed between the focusing electrode and the accelerating electrode can reduce the spot size in both the center and the peripheral part of the screen, thereby improving the focus level.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a schematic cross-sectional view of a cathode ray tube according to an embodiment of the present invention.

Referring to FIG. 1, the cathode ray tube 100 of the present embodiment includes a vacuum tube including a face panel 12, a funnel 14, and a neck 16. The inner surface of the face panel 12 is formed with a fluorescent screen 18 composed of a red, green, blue phosphor layer and a black layer, and inside the neck 16 an electron gun emitting a three-stage electron beam toward the fluorescent screen 18 ( 30) is located. The outer periphery of the funnel 14 is equipped with a deflection yoke 20 for generating a deflection magnetic field to deflect the electron beam.

In addition, a shadow mask 22, which is a color screening electrode, is formed inside the face panel 12 to form a plurality of electron beam through holes at a predetermined distance from the fluorescent screen 18. The shadow mask 22 selects three stem electron beams emitted from the electron gun 30, and serves to land each electron beam into a phosphor of a corresponding specific color.

The cathode ray tube 100 expands the deflection angle θ of the electron beam by strengthening the deflection magnetic field generated by the deflection yoke 20 to reduce the total length L1 measured along the tube axis direction (z-axis direction in the drawing). have. In this embodiment, the deflection angle of the electron beam may be 120 °.

The enlarged deflection angle means that the electron gun 30 moves toward the deflection yoke 20, in which case the focus level of the electron beam is lowered. In order to solve this problem, it is necessary to reduce the length of the deflection yoke 20 or reduce the length of the electron gun 30. In this embodiment, a method of reducing the length of the electron gun 30 is applied. In addition, since the focus level is expected to be reduced even when the length of the electron gun 30 is shortened, the cathode ray tube 100 of the present embodiment provides the structure of the electron gun 30 which can improve the focus level.

2 is a front view of an electron gun for a cathode ray tube according to an embodiment of the present invention, FIG. 3 is a horizontal cross-sectional view of the electron gun shown in FIG. 2, and FIG. 4 is a vertical cross-sectional view of the electron gun shown in FIG. 2.

2 to 4, the electron gun 30 of the present embodiment is sequentially disposed along three cathodes 32 that emit electrons and along the tube axis direction (z-axis direction) of the cathode ray tube from the cathode 32. The control electrode 34, the screen electrode 36, the focusing electrode 38, and the acceleration electrode 40 are included. The control electrode 34, the screen electrode 36, the focusing electrode 38, and the acceleration electrode 40 form three apertures for passing the electron beam, and are fixed to the bead glass 42 serving as a support to each other. Located at a distance.

The control electrode 34 and the screen electrode 36 are formed in a plate shape and together with the cathode 32 constitute a triode portion.

The focusing electrode 38 may be composed of a single electrode or a plurality of electrodes receiving the same voltage. 2 to 4 illustrate a case in which the focusing electrode 38 includes three electrodes. For convenience, the three electrodes are referred to as the first focusing electrode 381, the second focusing electrode 382, and the third focusing electrode 383 from the side close to the cathode 32. The number and shape of the focusing electrodes 38 are not limited to the illustrated example and can be variously modified.

In the illustrated example, the first focusing electrode 381 is formed in a plate shape, and the second focusing electrode 382 and the third focusing electrode 383 have a cylinder having a bottom surface on the side where the electron beam enters and the side where the electron beam exits. It may be formed into a shape.

The acceleration electrode 40 may be formed in a cup shape having a bottom surface on the side where the electron beam enters, and a plate-shaped electrode member 401 may be located inside the acceleration electrode 40.

The control electrode 34 receives the first constant voltage V1, and the screen electrode 36 receives the second constant voltage V2 higher than the first constant voltage V1. The focusing electrode 38 receives a fixed focus voltage Vf_static, and the acceleration electrode 40 receives the highest anode voltage Va among the electrodes. For example, the first constant voltage V1 may be set to 0 V, the second constant voltage V2 to 400 V, the fixed focus voltage Vf_static to 5 kV, and the anode voltage Va to 20 to 30 kV.

The screen electrode 36 and the first focusing electrode 381 form a pre-focus lens between the two electrodes by the voltage difference between the two electrodes. The third focusing electrode 383 and the acceleration electrode 40 form a main-focus lens between the two electrodes by the voltage difference between the two electrodes. Thus, the electron beam emitted from the cathode 32 forms a corss-over point at the triode, and the electron beam forming the water point is pre-focused by the pre-focus lens and then finally focused by the main-focus lens to form a fluorescent screen. It forms into a spot at 18.

As described above, the electron gun 30 of the present embodiment is constituted by a bi-potential system. This configuration can effectively reduce not only the length L2 (see FIG. 2) of the electron gun 30, but also the total length L1 (see FIG. 1) of the cathode ray tube 100 on which the electron gun 30 is mounted.

5 is a schematic diagram illustrating the relationship between an object point, a main-focus lens, and a spot.

Referring to FIG. 5, the spot size D formed on the fluorescent screen can be defined as the product of the spot size (d) and the lens magnification (M), assuming that there are no effects of spatial charge repulsion and spherical aberration. have. (D = d × M) and the lens magnification M approximately correspond to the ratio of the distance b between the main-focus lens and the fluorescent screen to the distance a between the object point and the main-focus lens. (D = d × (b / a))

Based on the above, in order to reduce the spot size (D), it is necessary to reduce the spot size (d), reduce the distance between the main-focus lens and the fluorescent screen (b), or decrease the distance between the object and the main-focus lens (a). It should be loud. However, when the length of the electron gun 30 becomes smaller, the distance a between the object point and the main-focus lens becomes smaller and the lens magnification M and the spot size D become larger. This is the reason that the focus level is sharply lowered in the electron gun 30 having a reduced length.

On the other hand, since the deflection angle of the cathode ray tube 100 is enlarged to 120 °, the distance b between the main-focus lens and the fluorescent screen is reduced. As a result, the lens magnification M can be maintained in the same manner as before even though the length of the electron gun 30 is reduced.

In the electron gun 30 of the present embodiment, the spot size D enlarged by the shortening of the length of the electron gun 30 can be solved by reducing the object size d. The main factor determining the object size d is the aperture size of the control electrode 34.

FIG. 6 is a plan view of the control electrode illustrated in FIG. 2, and FIG. 7 is an enlarged plan view illustrating the aperture of the control electrode illustrated in FIG. 6.

6 and 7, the control electrode 34 forms three apertures 341 with the horizontal width H minimized. That is, the control electrode 34 forms three apertures 341 in which the vertical width V is greater than the horizontal width H (V / H> 1), and the horizontal width H of each aperture 341. ) Is made small in accordance with the critical size of the cathode load. This is because the initial emission and the emission lifetime deteriorate when the size of the control electrode aperture 341 is smaller than the threshold size of the cathode load.

As the horizontal width H of the control electrode aperture 341 is reduced in this way, the size of the effective area in which the actual electrons are emitted from the cathode 32 can be reduced to reduce the size of the object point d in the horizontal direction. . Therefore, the focus level can be improved by reducing the spot size D in the horizontal direction.

On the other hand, the object point size d in the vertical direction becomes large due to the shape of the aperture 341 described above, but the vertical spot size in the center of the fluorescent screen 18 is not deteriorated for the reason described below.

In general, the divergence angle in the horizontal direction incident on the main-focus lens is set substantially to the optimization beam diameter of the main-focus lens, and the divergence angle in the vertical direction is set smaller than the optimization beam diameter of the main-focus lens. As a result, when the divergence angle in the horizontal direction is enlarged, the horizontal spot size is enlarged under the influence of spherical aberration, but in the vertical direction, the divergence angle can be enlarged to the extent of reaching the optimized beam diameter. Therefore, even if the divergence angle in the vertical direction is enlarged by the shape 341 of the control electrode 34, the vertical spot size at the center of the fluorescent screen 18 does not deteriorate.

In addition, the electron gun 30 of the present embodiment forms a main-focus lens that implements a strong focusing force in the vertical direction as follows to improve the focus level around the fluorescent screen 18. This is because the vertical size of the electron beam incident on the deflection magnetic field must be reduced in order to reduce the influence of the electron beam by the deflection magnetic field and improve the focus level.

Referring again to FIGS. 3 and 4, the main-focus lens is formed between the focusing electrode 38 and the accelerating electrode 40, and in this embodiment, the focusing electrode 38 is composed of three electrodes and thus, the third focusing lens. A main-focus lens is formed between the electrode 383 and the acceleration electrode 40.

One side of the third focusing electrode 383 facing the acceleration electrode 40 is formed with a first rim 44 extending toward the acceleration electrode 40 and forming one aperture. 8 illustrates a third focusing electrode in a state where the third focusing electrode is viewed from the acceleration electrode position.

The first rim 44 has a predetermined width d1 along the circumference of the third focusing electrode 383, and has a predetermined height from a bottom surface (electron beam exit surface) of the third focusing electrode 383 on which the electron beam exits. (h1, see FIGS. 3 and 4).

In addition, a second rim portion 46 extending toward the third focusing electrode 383 and forming one aperture is formed at one side of the acceleration electrode 40 facing the third focusing electrode 383. 9 illustrates an acceleration electrode in a state where the acceleration electrode is viewed from the third focusing electrode position.

The second rim 46 has a constant width d2 along the circumference of the acceleration electrode 40, and has a predetermined height h2 from the bottom surface (electron beam incident surface) of the acceleration electrode 40 on which the electron beam enters. 3 and 4).

At this time, the width d1 of the first rim 44 is smaller than the width d2 of the second rim 46 (d1 <d2), and the height h1 of the first rim 44 is the second rim. It is formed larger than the height h2 of 46 (h1> h2).

10 is a simulation diagram showing an equipotential distribution and electron beam trajectory in a vertical direction in an electron gun for a cathode ray tube according to an embodiment of the present invention.

Referring to FIG. 10, a focusing lens is formed at the third focusing electrode 383 side due to a low potential of the focusing electrode 38 and a high potential of the accelerating electrode 40, and a diverging lens is formed at the accelerating electrode 40. The main-focus lens is formed between the third focusing electrode 383 and the accelerating electrode 40 by using the synthesized electric field.

And the main-focus lens due to the width difference d1 <d2 of the first rim 44 and the second rim 46 and the height difference h1> h2 of the first rim 44 and the second rim 46. Becomes more convex toward the focusing electrode 40. That is, the main-focus lens is formed asymmetrically.

In the vertical direction, the electron beam incident side of the main-focus lens, that is, the third focusing electrode 383 side passes through the main-focus lens after the vertical electron beam size is enlarged by the aperture 341 shape of the control electrode 34. The focusing action of the electron beam is strong. In addition, on the acceleration electrode 40 side, due to the small height h2 of the second rim portion 46, the inclination of the high potential side electric field distribution becomes sharp, and the divergence action of the electron beam appears strongly.

Accordingly, even though the vertical size of the electron beam incident on the main-focus lens is enlarged, the vertical size leaving the electron gun 30 is reduced by the above-described main-focus lens configuration. In addition, since the divergence in the horizontal direction and the focusing effect in the vertical direction that the electron beam receives by the deflection magnetic field can be reduced, the electron gun 30 of the present embodiment can improve the focus level of the periphery of the screen.

In the electron gun 30 structure of the bi-potential system described above, the control electrode aperture 341 has a horizontal width H of 0.45 mm and a vertical width V of 0.60 mm, and is fixed to the anode voltage Va. The simulation results measured under the condition that the ratio (focus ratio) of the focus voltage Vf_static is 21% are shown in the following table.

In addition, in the electron gun of the known Uni-Bi potential, Unipotential plus bipotential system, the control electrode aperture has a horizontal width of 0.54 mm and a vertical width of 0.48 mm and has a focus ratio of 26%. The measured simulation results are shown in the table below.

Referring to Tables 1 and 2, the electron gun of this embodiment reduces the horizontal size for spots formed in the center of the fluorescent screen, and reduces the difference between the horizontal size and the vertical size for spots formed at the corners of the fluorescent screen. You can see that the overall focus level is improving.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

1 is a schematic cross-sectional view of a cathode ray tube according to an embodiment of the present invention.

2 is a front view of an electron gun for a cathode ray tube according to an embodiment of the present invention.

3 is a horizontal cross-sectional view of the electron gun shown in FIG. 2.

4 is a vertical cross-sectional view of the electron gun shown in FIG. 2.

5 is a schematic diagram illustrating the relationship between an object point, a main-focus lens, and a spot.

6 is a plan view of the control electrode illustrated in FIG. 2.

FIG. 7 is an enlarged plan view illustrating the aperture of the control electrode illustrated in FIG. 6.

FIG. 8 is a front view illustrating a third focusing electrode in a state where the third focusing electrode is viewed at an acceleration electrode position among the electron guns illustrated in FIG. 3.

FIG. 9 is a front view illustrating an acceleration electrode in a state where the acceleration electrode is viewed at a third focusing electrode position among the electron guns illustrated in FIG. 3.

10 is a simulation diagram showing an equipotential distribution and electron beam trajectory in a vertical direction in an electron gun for a cathode ray tube according to an embodiment of the present invention.

Claims (9)

A plurality of cathodes emitting electrons; And Control electrodes, screen electrodes, focusing electrodes, and acceleration electrodes that are sequentially positioned at a distance from each other from the plurality of cathodes Including; The control electrode forms three apertures whose vertical width is greater than the horizontal width, The focusing electrode forms a first rim positioned at a first height toward the acceleration electrode from the electron beam exit surface of the focusing electrode on one side facing the acceleration electrode, The acceleration electrode forms a second rim positioned at a second height toward the focusing electrode from the electron beam incident surface of the acceleration electrode on one side facing the focusing electrode, And a first height greater than the second height, and a width of the first rim portion smaller than that of the second rim portion. The method of claim 1, And a horizontal width of the control electrode aperture corresponds to a critical size of the cathode load. The method of claim 1, An electron gun for a cathode ray tube to which the focusing electrode is applied a fixed focus voltage. The method of claim 3, And a first focusing electrode, a second focusing electrode, and a third focusing electrode, wherein the focusing electrodes are positioned at a distance from each other, wherein the third focusing electrode forms the first rim. The method of claim 4, wherein The first focusing electrode is formed in a plate shape, the second focusing electrode and the third focusing electrode is an electron gun for a cathode ray tube formed in a cylindrical shape having a bottom surface on the side that the electron beam enters and the electron beam exits. A vacuum tube comprising a face panel and a funnel and a neck; A fluorescent screen formed on an inner surface of the face panel; A deflection yoke installed at an outer circumference of the funnel; And An electron gun having a plurality of cathodes disposed inside the neck and emitting electrons, and a control electrode, a screen electrode, a focusing electrode, and an acceleration electrode sequentially positioned at a distance from each other from the plurality of cathodes. Including, The control electrode forms three apertures having a vertical width greater than a horizontal width, and the focusing electrode is positioned at a first height toward the acceleration electrode from an electron beam exit surface of the focusing electrode on one side facing the acceleration electrode. A first rim portion is formed, and the acceleration electrode forms a second rim portion positioned at a second height toward the focusing electrode from an electron beam incident surface of the acceleration electrode on one side facing the focusing electrode. The cathode ray tube of which the first height is greater than the second height and the width of the first rim portion is smaller than the width of the second rim portion. The method of claim 6, A horizontal width of the control electrode aperture is formed corresponding to a threshold size of the cathode load. The method of claim 6, The focusing electrode receives a fixed focus voltage and includes a first focusing electrode, a second focusing electrode, and a third focusing electrode positioned at a distance from each other, wherein the third focusing electrode forms a first rim. tube. The method of claim 6, Cathode ray tube that the deflection yoke implements a deflection angle of 120 °.

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