KR20020021486A - Electron gun for cathode ray tube - Google Patents

Abstract

PURPOSE: An electron gun for a cathode ray tube is provided to obtain uniform electron beam cross section over whole screen and improve resolution of an image by enhancing focus characteristic of the electron beam that is landed on the boundary of the screen. CONSTITUTION: An electron gun for a cathode ray tube comprises a cathode(51), a control electrode(52), a screen electrode(53), a first focus electrode(54) adjacent to the screen electrode(53), at least a second and a third focus electrodes(61,62) adjacent to the first electrode(54) for a quadrupole lens, and a final acceleration electrode(55) adjacent to the third focus electrode(62). The control electrode(52) and the screen electrode(53) are of plates and the focus electrodes(54,61,62) are cylindrical. When an electron beam is scanned to a center of a luminescent film, a focus voltage is applied to the second focus electrode(61) and a dynamic focus voltage that is substantially same as the focus voltage is applied to the third focus electrode(62). Therefore, the second and the third electrodes(61,62) does not form the quadrupole lens.

Description

Electron gun for cathode ray tube

The present invention relates to an electron gun for cathode ray tubes, and more particularly to an electron gun for monochrome cathode ray tube forming a monochrome image.

A cathode ray tube for forming a monochrome image, in particular, a monochromatic cathode ray tube used for projection television, has a screen surface 11 and a bulb 10 having a fluorescent film 12 formed on the inner surface of the screen surface, as shown in FIG. Include. The neck portion 13 of the bulb 10 is provided with an electron gun 20 for emitting an electron beam for exciting the fluorescent film, and the cone portion of the bulb 10 is deflected for deflecting the electron beam emitted from the electron gun 20. Yoke 30 is installed.

In the cathode ray tube as described above, the electron beam emitted from the electron gun 20 is deflected by the deflection yoke 30 to be scanned into the fluorescent film to form an image.

Three cathode ray tubes having a configuration for forming such an image are used when configuring a projector for forming a color image. That is, the projector forms a red, green, and blue image by three cathode ray tubes, respectively, and synthesizes them on a projection screen to form a color image. Therefore, in order to increase the resolution and luminance of the image projected on the projection screen, the luminance of the cathode ray tube must be increased. Because the viewer views the image formed by each cathode ray tube on the screen through the projection lens rather than directly, it is impossible to see a clear image when the brightness is low. In order to increase the brightness of the cathode ray tube, the current density of the electron beam emitted from the electron gun must be increased and the electron beam emitted from the electron gun must be accurately landed.

In particular, in the electron gun used in the projector, an electron gun of a universal potential connection that is capable of two-stage prefocusing is used to improve the focusing of the electron beam at high current.

2 shows an example of such an electron gun.

The electron gun as shown is disclosed in U.S. Patent No. 4,904,898. The cathode 21, the control electrode 22, and the screen electrode 23 for emitting hot electrons are installed and divided adjacent to the screen electrode. A lower focus electrode 24 and an upper focus electrode 25 and a final acceleration electrode 26 surrounding the end of the upper focus electrode 25 are provided. Herein, a circular electron beam through hole is formed in the control electrode 22 and the screen electrode 23, and the focus electrode and the final acceleration electrode are formed in a cylindrical shape.

After a predetermined voltage is applied to each electrode of the color cathode ray tube electron gun configured as described above, an electron lens is formed between the electrodes, and the electron beam emitted from the cathode 21 is focused and accelerated while passing through the electron lenses. It is deflected by the deflection yoke 30 (refer to FIG. 1) and becomes a fluorescent film. In this process, since the fluorescent film 12 having the screen surface 11 of the cathode ray tube has a predetermined curvature, the focus characteristic of the electron beam is deteriorated due to the difference in the focal length of the electron beam emitted and deflected from the electron gun 20. There is this. In particular, the development of digital cathode ray tubes has made the focus of the periphery of the screen important. In the area where the curvature radius of the screen surface is 350mm or 600mm, the horizontal and vertical flat beam diameters can be improved, but the deflection yoke can be improved. The distortion of the beam mirror by 30 has a problem that is not greatly improved.

The present invention is to solve the above problems, to improve the focus characteristics of the electron beam landing to the periphery of the screen to have a uniform electron beam cross section on the entire screen and further to provide an electron gun for cathode ray tube that can improve the resolution of the image There is a purpose.

1 is a cross-sectional view of a conventional cathode ray tube,

2 is a side view of an electron gun for a conventional cathode ray tube;

3A is a cross-sectional view of an electron gun for a cathode ray tube according to the present invention;

FIG. 3B is a perspective view illustrating the second and third focus gains shown in FIG. 3A;

4A is a cross-sectional view showing another embodiment of an electron gun for a cathode ray tube according to the present invention;

4B is a perspective view illustrating extracting electrodes forming the quadrupole lens illustrated in FIG. 4A;

5 to 7 is a view showing a visualized electron lens formed by the electron gun,

In order to achieve the above object, the electron gun of the present invention,

Cylindrical first and second focus electrodes having a cathode, a control electrode and a screen electrode constituting the triode, and non-circular electron beam through holes sequentially formed from the screen electrode to form at least one quadrupole lens; The focus electrode wraps the final focus electrode away from the cathode and is characterized by including a final acceleration electrode for forming the final focus electrode and the main lens.

In the present invention, one elongated electron beam through hole is formed on the emission side of the first focus electrode located on the cathode electrode side, and one incident side of the second focus electrode located on the final acceleration electrode side. An elongated electron beam through hole is formed.

The first focusing electrode is divided into a first electrode member and a second electrode member, and a horizontal electron beam passing hole is formed at the exit side of the first electrode member and the incidence side of the third focus electrode positioned on the cathode electrode side. And an elongated electron beam through hole is formed at the incidence side and the exit side of the second electrode member, a focus voltage is applied to the second electrode member, and synchronized with a deflection signal to the first electrode member and the third focus electrode. A dynamic focus voltage is applied. The aspect ratio of the seed electron beam through hole and the horizontal electron beam through hole can be adjusted according to the formation strength of the quadrupole lens.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An example of an electron gun used in the electron gun according to the present invention and a cathode ray tube employing the electron gun, that is, a cathode ray tube for forming an image of one of red, blue and green images of a projector is shown.

As shown in FIG. 3, the electron gun is positioned so as to be adjacent to the cathode 51, the control electrode 52 and the screen electrode 53, and the screen electrode 53, which form a transposition triode as shown in FIGS. 3A and 3B. First and second focus electrodes 54 and 62 and 62 and 62 are disposed adjacent to the first focus electrode to form a quadrupole lens, and the focus electrode 61. And a final accelerating electrode 55 disposed adjacent to the focus electrode 62 (hereinafter, referred to as a final focus electrode) farthest from the cathode 51 of the chopper 62 to form a main lens. The control electrode 52 and the screen electrode 53 may be formed of a plate-like electrode, the focus electrodes may be formed in a cylindrical shape. Here, one longitudinal electron beam through hole 64 is formed on the emission side of the second focus electrode 62 among the second and third focus electrodes 61 and 62 forming the quadrupole lens. On the incidence side surface of the three focus electrode 63, a transverse electron beam through hole 65 is formed.

Meanwhile, a predetermined voltage is applied to each electrode constituting the electron gun, and a predetermined voltage is applied to each electrode constituting the electron gun. A focus voltage vf of 7 to 8 kv is applied to the second focus electrode 61. And a die-naming focus voltage vd having the focus voltage vf as a base voltage is applied to the third focus electrode, and an anode voltage ve of 28 to 32kv is applied to the final acceleration electrode 55. Is approved.

And another embodiment of the electron gun for color cathode ray tube according to the present invention is shown in Figures 4a and 4b. In this embodiment, the same reference numerals refer to the same components as the above-described embodiment.

As shown, the electron gun for the color cathode ray tube separates the second focus electrode forming the quadrupole lens into first and second electrode members 61a and 61b, and is transverse to the emission side of the first electrode member 61a. An elongated electron beam through hole 66 is formed, and an elongated electron beam through hole 67 and 68 is formed on the incident side and the exit side of the second electrode member 61b, respectively. A transverse electron beam through hole 69 is formed on the incident side surface of the third focus electrode 62. In the electron gun configured as described above, a focus voltage vf is applied to the second electrode member 61b and the focus voltage vf is applied to the first electrode member 61a and the third focus electrode 62. When the base voltage is used, a parabola type dynamic focus voltage vd synchronized with the deflection signal is applied.

In the two embodiments as described above, the aspect ratio of the longitudinal electron beam passing hole and the horizontal electron beam passing hole forming the quadrupole lens can be adjusted in consideration of the strength of the quadrupole lens.

Referring to the operation of the electron gun for the color cathode ray tube according to the present invention configured as described above are as follows.

First, as a predetermined potential is applied to the electrode forming the cathode ray tube electron gun, as shown in FIGS. 5 to 7, an electron lance is formed between the electrodes by a voltage difference.

As described above, the intensity of the electron lens, the lens formation state, and the focusing state of the electron beam vary depending on the position of the electron lens formed between the electrodes, which is determined when the electron beam is scanned in the center of the fluorescent film. When divided into the injection when the peripheral is as follows.

First, as shown in FIG. 3A, an electron gun provided with means for forming a quadrupole lens in the second and third focus electrodes 61 and 62 is provided. When the electron beam is scanned in the center of the fluorescent film, the second focus electrode is used. Since a focus voltage vf is applied to the 61 and a dynamic focus voltage vd equal to the focus voltage is applied to the second focus electrode, quadrupole lenses are applied to the second and third focus electrodes 61 and 62. It will not form.

Thus, as shown in FIG. 5, the electron beam emitted from the cathode 51 is formed between the screen electrode 53 and the first focus electrode 54 and the third focus electrode PL. The light is focused and accelerated while passing through the main lens ML formed between the final acceleration electrode 55 and the final acceleration electrode 55, and landed at the center of the fluorescent film at the best state.

When the electron beam emitted from the electron gun is scanned at the periphery of the fluorescent film, the focus voltage vf synchronous with the deflection signal to the third focus electrode 63 of the second and third focus electrodes 62 and 63 is a base voltage. A dynamic focus voltage (vd) synchronized with the deflection signal is applied, and a relatively high enowood voltage (ve) is applied to the final acceleration electrode (55). Therefore, as shown in FIG. 6, a prefocus lens PL is formed between the screen electrode 53 and the first focus electrode 54, and between the second and third focus electrodes 61 and 62. A quadrupole lens QL is formed in the main lens, and a main lens ML is formed between the third focus electrode 63 and the final acceleration electrode 55.

Therefore, the electron beam emitted from the cathode 51 is focused and accelerated by the quadrupole lens after being prefocused and accelerated while passing through the prefocus lens PL. The second focus electrode 62 forming the quadrupole lens 62 is formed. Longitudinal electron beam through-hole 64 is formed on the emission side of the side, and a transverse electron beam through-hole 65 is formed on the incident side of the third focus electrode 63, so that the quadrupole lens is vertical in the vertical direction. The difference in focusing force occurs in the direction and the horizontal direction. Therefore, the electron beam emitted from the cathode 51 receives a weak focusing force and a strong divergence force in the vertical direction, and receives a strong focusing force and a weak divergence force in the horizontal direction, thereby forming an elongated cross section of the electron beam. As described above, the electron beam lengthened by the difference between the focusing force and the diverging force passes through the main lens ML formed between the third focusing electrode 62 and the final accelerating electrode 55. Since the potential difference is reduced due to the application of the dynamic focus voltage to the third focus electrode 62, the magnification of the main lens is reduced, so that spherical aberration is reduced and the focus length is long.

As described above, the electron beam, which is formed by receiving the focusing force and the diverging force, is deflected by the lens DL formed by the deflection magnetic field of the deflection yoke 30 (see FIG. 1) and is landed at the periphery of the fluorescent film. At this time, the elongated electron beam receives the focusing force in the longitudinal direction by the low lens effect when the deflection magnetic field passes, thereby preventing the end surface of the electron beam from being distorted when landing at the periphery of the fluorescent film.

In the electron gun as shown in FIGS. 4A and 4B, when the electron beam is deflected toward the periphery of the fluorescent film, between the first and second electrode members 61a and 61b and between the second electrode member 61b and the third focus. A non-circular electron beam electron beam through hole for forming the quadrupole lens QL is formed between the electrodes, and a dynamic focus voltage is applied to the first electrode member 61b and the third focus electrode 62 in synchronization with the deflection signal. Therefore, as shown in FIG. 7, the quadrupole lens is formed to prevent cross-sectional distortion of the electron beam in the deflection magnetic field of the deflection yoke 30 and the geometric curvature of the screen surface.

As described above, the present invention can reduce the distortion caused by the deflection magnetic field caused by the deflection of the electron beam by forming the quadrupole lens by the non-circular electron beam through hole in the electron gun of the monochromatic cathode ray tube used in the projector. The cross section of can be formed.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (3)

Cylindrical first and second focus electrodes having a cathode, a control electrode and a screen electrode constituting the triode, and non-circular electron beam through holes sequentially formed from the screen electrode to form at least one quadrupole lens; Electron gun for cathode ray tube, characterized in that it comprises a final acceleration electrode that surrounds the final focus electrode away from the cathode of the focus electrode and forms the final focus electrode and the main lens In the present invention, First focus electrodes forming the quadrupole lens An elongated electron beam through hole is formed on the emission side of the first focus electrode positioned on the cathode electrode side, and the second focus electrode positioned on the final acceleration electrode side of the first focus electrode. On the incident side, a horizontal electron beam through hole is formed. A predetermined focus voltage is applied to the first focus electrode, and a dynamic focus voltage synchronized with a deflection signal is applied to the second focus electrode as a base voltage. Electron gun for cathode ray tube, characterized in that applied. The method of claim 1, The first focusing electrode is divided into a first electrode member and a second electrode member, and a horizontal electron beam passing hole is formed at the emission side of the first electrode member and the incidence side of the third focus electrode positioned on the cathode electrode side. And an elongated electron beam through hole is formed at the incidence side and the exit side of the second electrode member, a focus voltage is applied to the second electrode member, and synchronized with a deflection signal to the first electrode member and the third focus electrode. Electron gun for cathode ray tube, characterized in that the dynamic focus voltage is applied.