KR980009935A - Electron gun for color cathode ray tube - Google Patents

Abstract

An electron gun for a cathode ray tube is disclosed. The electron gun includes a cathode structure including a cell having an electron emitting portion formed of a field emission device, a focus electrode forming a lens for focusing and accelerating the electron beam emitted from the electron emitting portion, a cathode electrode This electron gun is characterized in that the electron emitting portion is of a transversely elongated shape, and it is possible to prevent the cross section of the electron beam scanned on the peripheral portion of the screen from being transversely elongated.

Description

Electron gun for color cathode ray tube

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to an electron gun for a color cathode ray tube having an improved triode.

As shown in FIG. 1, a typical cathode ray tube comprises a panel 10 on which a fluorescent film is formed on the inner surface, and an electron gun 30 and an electron gun 30 on the net portion 2! And the cone portion 22, And a funnel 20 provided with a deflection yoke 23. In the cathode ray tube thus configured, the electron beam emitted from the electron gun is deflected by the deflection yoke and is scanned into the fluorescent film, thereby exciting the fluorescent film to form an image.

FIG. 2 shows an example of an electron gun mounted on a neck portion of the funnel to emit thermoelectrons.

The electron gun includes a cathode structure 31, a control electrode 32 and a screen electrode 33 constituting a triode portion, a focus electrode 34 sequentially formed from the screen electrode 33 and forming an electron lens, (35). Here, a negative electrode used in the negative electrode structure 31 is a heat-dissipative negative electrode which heats the electron-emitting material by a heater to emit a hot electron.

In the electron gun constructed as described above, electrons are emitted from the cathode structure 31 by applying a predetermined potential to the cathode structure 31 and the electrodes, and an electron lens is formed between the electrodes. Therefore, the electrons emitted from the cathode structure 31 are connected and accelerated while passing through the electron lens formed between the respective electrodes.

The beam current density of the electrons emitted from the electron gun and the time until the electron beam is normally emitted is dominated by the cathode structure 31. Therefore, in the electron gun, the cathode structure 31 as an emission source of electrons will be more important than ever.

However, although the triode portion of the conventional electron gun for a color cathode ray tube has been inevitably used to control electrons emitted and emitted electrons, the charge repulsion effect due to the nonuniformity of the current distribution due to the use of the triode portion, The characteristics of the electron beam diameter landed on the fluorescent film due to the aberration of the electron beam are limited to the improvement effect of the main lens and a problem is encountered in the changing focus characteristic of the electron beam diameter and the beam diameter of the electron beam.

As another example of the conventional electron gun, when the field emitter is used as the cathode structure of the triode, even if the current density generated from the field emitter is constant, as described in the above-mentioned electron gun, The influence is still present.

In order to solve such a problem, the electron gun which received the field emitter of the present invention was filed as Korean Patent Application No. 96-2071.

The electron gun employing the field emission device as the triode portion includes a cathode structure 50 having a cell 51 composed of three electron emitting portions 51a of a field emission device as shown in FIG. 3, A focus electrode 42 forming a main lens for connecting the electron beam emitted from the field emission device 50 and a final acceleration electrode 43. The electron emission portion 51a made of the field emission device is shown in FIG. And is formed in the same circular shape as the electron beam passage hole 42a formed in the focus electrode 42 as shown.

Since the cross section of the electron beam emitted from the field emission device is circular, the cross section of the electron beam incident on the main lens formed between the focus electrode 42 and the final acceleration electrode 43 is circular .

Is converged and accelerated by a main lens of an electron beam having a circular cross section incident on the main lens, is deflected by the deflection yoke, and is landed on the fluorescent film. In the landing process as described above, the main lens converges and accelerates and is deflected by the deflection yoke upon deflection toward the periphery of the fluorescent film. The electron beam deflected while passing through the magnetic field formed by the vertical and horizontal deflection coils converges Uniform magnetic field composed of a pinned magnetic field and a barrel magnetic field to distort and to be distorted into an elliptical shape due to the geometric curvature of the screen surface.

As described above, the cross section of the electron beam landed on the fluorescent screen at the periphery of the screen can not be gauged, the horizontal component is horizontal, and the vertical component is haze due to the over-focused beam. And the resolution of the image is lowered.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to improve the resolution of an image by compensating distortion of an electron beam cross section when an electron beam is actuated by a deflection yoke by making a cross- And an electron gun for a cathode-ray tube.

Figure 1 is a cross-sectional view of a typical cathode ray tube.

FIG. 2 is a sectional view of a conventional electron gun. FIG.

FIG. 3 is a sectional view showing another embodiment of the conventional electron gun. FIG.

4 is a front view of the cathode structure;

FIG. 5 is a perspective view of an electron gun according to the present invention; FIG.

6 is a sectional view showing an electron emitting portion of the cathode structure;

Figs. 8 and 8 are front views showing another embodiment of the cathode structure. Fig.

DESCRIPTION OF THE REFERENCE NUMERALS

60: cathode structure 71: focus electrode

61: cell (of negative electrode structure) 61a: electron emitting portion

According to an aspect of the present invention, there is provided an electron emission device, including: a cathode structure including a cell having an electron emitting portion made of a field emission device; a focus electrode forming a lens for focusing and gauzing an electron beam emitted from the electron emitting portion; An electron gun for a cathode ray tube having an electrode, characterized in that a region where the electron emitting portion of the cell is formed has a transverse shape

In the present invention, the electron emitting portion is formed into a rectangular or elliptical shape of a transverse elongated shape.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 shows an embodiment of an electron gun for a color cathode-ray tube according to the present invention.

The electron gun for a color cathode ray tube includes a cathode structure 60 including a cell 61 having an electron emitting portion 61 of an electron emission source made of a cathode emitting element, And a focus electrode 71 and a final acceleration electrode 72 for focusing and accelerating the electron beam emitted from the electron source 60. Here, a plurality of focus electrodes may be provided for multi-stage focusing of electron beams.

The electron emitting portion 61a formed in the cell 61 of the cathode structure 60 is provided so as to correspond to the incident electron beam passing hole 71H of the focus electrode 71 as shown in FIG. A silicon electrode layer 61c is formed on the upper surface of the substrate 61b made of silicon or the like and a plurality of metal tips 61d mainly composed of molybdenum are formed in the cathode electrode layer 61c. An insulating layer 61e made of SiO2 is formed around the metal tip 61d. Here, the metal tip 61d is exposed to the outside because the insulating layer 61e is formed around the metal tip 61d. A gate electrode layer 61f having a gate is formed on the upper surface of the insulating layer 61e to expose the metal tip 61d. The gate electrode 61f is opposed to the metal tip 61d. Since the electric current per one metal tip provided on the substrate is about 80 nA to 100 nA, if the number of the metal tips is at least 10,000 or more in the field emission element formation region 61a of the electron emitting portion of one electron gun, There is enough current to excite the film.

The formation region of the electron emitting portion 61a configured as described above is formed in the shape of an ellipse or a rectangle having a transverse elongated shape as shown in Figs. 7 and 8 in accordance with the features of the present invention. It is a matter of course that the emitting region of the field emission device is formed in a transversely elongated shape without being limited to the above-described embodiment.

The operation of the electron gun for a color cathode-ray tube according to the present invention will now be described.

When a predetermined potential is applied to the focus electrode 71 and the final angular velocity electrode 72 constituting the electron gun in a state where the electron gun is mounted on the funnel neck portion of the cathode ray tube, A lens is formed. The electron beam is emitted from the metal tip of the electron emitting portion of the cathode structure 60. The electron beam emitted as described above is converged and accelerated after passing through the above-mentioned electron lenses, and is then deflected by the deflection yoke to be landed at the fluorescent spot of the fluorescent film to excite the fluorescent film.

As described above, since the electron emitting portion forming region 61a of the cathode structure, that is, the electron beam emitting region, has a transverse elongated shape, the cross section of the electron beam passing through the electron emitting portion has a transverse elongated cross section. The distortion due to the nonuniformly deflected magnetic field is less received when the pincushion magnetic field and the barrel magnetic field pass through the deflection region.

Therefore, the cross section of the electron beam passing through the deflection region has a shape close to the circle, so that the electron beam landed on the periphery of the fluorescent film is prevented from being horizontally elongated and having a vertically severe haze.

More specifically, the electron beam emitted from the electron emitting portion of the cell 61 is incident on the main lens at an exit angle of about 20 degrees from the exit, And the spherical aberration of the main lens is greatly increased. On the other hand, in the horizontal direction of the screen, the spherical aberration of the main lens is greatly increased. On the other hand, in the horizontal direction of the screen, the focusing power of the main lens and the biasing force of the deflection yoke have opposing forces, so that even if the area occupied by the beam in the main lens is somewhat large, self focusing is achieved. However, since the focusing power of the main lens and the deflection yoke of the deflection yoke are mutually increased in the vertical direction of the electron beam, the electron beam is over-focused at the periphery of the fluorescent film, The emission area of the electron beam is formed in a transversely elongated shape so that the cross section of the emitted electron beam is transversely elongated to reduce the occupied area in the vertical direction in the deflection area of the main lens and the deflection yoke to reduce spherical aberration in the main lens, Fan-type distortion can be reduced. Therefore, the cross section of the electron beam landed on the fluorescent film can be brought close to a circular shape.

As described above, in the electron gun for a color cathode ray tube of the present invention, since the area for forming the field emission device, which is the electron emission source, is formed in a transverse shape, the width of the electron beam in the vertical direction is reduced to reduce the used current density, The influence of defocusing at the periphery of the screen can be reduced. The electron gun according to the present invention is not limited to the above-described embodiments and can be modified by those skilled in the art within the technical scope of the present invention.

Claims (2)

A cathode structure including a cell having an electron emitting portion made of a field emission device array; a focus electrode forming a lens for focusing and accelerating the electron beam emitted from the electron emitting portion; and an electron gun for a cathode ray tube Wherein the field emission element array forming region of the electron emitting portion is made of a ferroelectric type. The electron gun for a cathode ray tube according to claim 1, wherein the field emission element array forming region of the electron emitting portion has a rectangular shape or a transversely elongated elliptical shape. ※ Note: It is disclosed by the contents of the first application.