KR20030070996A - A Electron gun of Cathode Ray Tube - Google Patents

Abstract

PURPOSE: An electron gun of a CRT(Cathode Ray Tube) is provided to be capable of considerably removing the halo phenomenon of the electron beam converged at a screen by minimizing the influence of spherical aberration at a uni-potential focus lens. CONSTITUTION: An electron gun of a CRT comprises a triode part, a uni-potential focus lens part, and a main lens part. The triode part includes a plurality of cathodes for emitting electron beam, the first electrode for controlling the emission dosage of the electron beam, and the second electrode. The uni-potential focus lens part includes the third and fifth electrode as a focus lens and the fourth electrode(26') located between the third and fifth electrode as an acceleration electrode. The main lens part includes the fifth electrode and the sixth electrode as an anode. The fourth electrode includes a plurality of electron beam passing holes, wherein each electron beam passing hole has a plurality of enlarged parts(40) to the diagonal directions.

Description

Electron Gun for Cathode Ray Tube {A Electron gun of Cathode Ray Tube}

The present invention relates to an electron gun for a cathode ray tube, and more particularly, to an electron gun capable of minimizing the deterioration phenomenon of an electron beam focused on a screen by minimizing spherical aberration characteristics in a universal potential lens.

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

As shown, the conventional cathode ray tube is a panel 10 having a phosphor 2 coated with R, G, and B fluorescent materials therein, and a funnel fusion-fixed with frit glass behind the panel 10. (12), an electron gun (20) enclosed in a neck portion (12a) provided behind the funnel (12) and irradiating electron beams of R, G, and B, and the color of the electron beam on the rear inner surface of the panel (10). It includes a shadow mask 14 is formed with a plurality of slits for screening, and a frame assembly (not shown) for supporting the shadow mask (14).

The funnel 12 includes a deflection yoke 16 for deflecting the electron beam irradiated from the electron gun 20 up and down, left and right, and a traveling trajectory so that the electron beam accurately strikes the phosphor forming the fluorescent surface 10a. A magnet (not shown) is installed to prevent poor color purity.

2 shows a general electron gun 20, three cathodes 21, a heater 22 inserted into the cathode 21, a first electrode 23 from the cathode 21, The second electrode 24, the third electrode 25, the fourth electrode 26, and the fifth electrodes 27 and 28 constituting the main lens unit and the sixth electrode 29 are spaced apart from each other by a predetermined distance. .

The cathode 21 of the electron gun 20 emits electrons by heating a heater 22 embedded therein by a voltage applied from a stem pin, and the electrons are controlled by the first electrode 23 which is a control electrode. And the electron beam is focused and accelerated by the shear focusing lens composed of the third electrode 25 and the fourth electrode 26, and is accelerated by the second electrode 24, which is an acceleration electrode. By the fifth electrodes 27 and 28 serving as the electrodes and the sixth electrode 29 called the anode electrode, the electron beam is mainly focused / accelerated and collides with the fluorescent surface 10a to emit light. In addition, a deflection yoke 16 is disposed outside the electron gun to deflect the electron beam emitted from the electron gun to the entire fluorescent surface, thereby realizing a screen.

Among the design characteristics of the electron gun, factors affecting the spot diameter on the screen include lens magnification, space charge repulsion force, and spherical aberration of the main lens. Among them, the influence of the spot diameter (Dx) due to the magnification of the lens is determined because the basic voltage conditions, focal length, and the length of the electron gun, etc. can be utilized as a design element is relatively small and the effect is minimal. The space charge repulsion force is a phenomenon in which the spot diameter is enlarged due to mutual repulsion and collision between electrons in the electron beam. In order to reduce the spot diameter (Dst) enlargement due to the space charge repulsion force, it is advantageous to design the angle at which the electron beam travels. On the other hand, the spherical aberration characteristic of the main lens refers to the enlargement of the spot diameter due to the difference in focal length between the electrons passing through the paraxial axis of the lens and the electrons passing through the lens axis, which is opposite to the space charge repulsion. If the divergence angle incident on the main lens is small, a smaller spot diameter can be realized on the screen. The spot diameter (Dt) on the screen is generally expressed as the sum of three elements as shown in the following equation.

Dt =

In the conventional electron gun, the electron beam is generated far away from the inner electron beam and the axis of the electron beam accelerated by the potential difference between the cathode 21, the first electrode 23, and the second electrode 24, which is generated near the center axis of the cathode. The traveling external electron beam is similar to the prefocus lens unit and the main lens unit so that the inner electron beam is close to the center of the lens, and the outer electron beam passes through the far position. Accordingly, the external electron beam is affected by the strong spherical aberration in comparison with the internal electron beam in both the prefocus lens part and the main lens part, so that the focus is much closer than the internal electron beam on the screen, so that the spot diameter on the screen is enlarged. As shown there is a problem causing halo. As a result, degradation of the resolution of the cathode ray tube, that is, focus failure is caused.

Accordingly, an object of the present invention is to solve the above problems, and to minimize the effect of spherical aberration in the universal potential lens, thereby minimizing the halo of the electron beam focused on the screen.

1 is a view showing a conventional cathode ray tube,

2 is a view showing an electron gun of a conventional cathode ray tube,

3 is a view showing the acceleration electrode (fourth electrode) shape of the unit of the conventional potential lens of the conventional cathode ray tube electron gun,

4 is a view showing the shape of the acceleration electrode (fourth electrode) of the unitary focus lens unit of the cathode ray tube electron gun of the present invention;

5 is a view showing an electron beam shape by a conventional electron gun,

6 is a view showing the shape of the electron beam by the electron gun of the present invention,

Explanation of symbols on the main parts of the drawings

12a; Neck

20; Electron gun 21; cathode

22; Heater 23; First electrode

24; Second electrode 25; Third electrode

26; Fourth electrode 27; Fifth electrode

28; A sixth electrode 30; Insulation support

40: extension

The electron gun of the cathode ray tube according to the present invention for achieving the above object, a three pole portion consisting of a plurality of cathodes for emitting an electron beam, a first electrode for adjusting the radiation amount of the electron beam, and a second electrode; A unpotential focus lens unit including a third electrode and a fifth electrode as two focusing electrodes and a fourth electrode as an acceleration electrode disposed between the third and fifth electrodes; And a main lens unit including a fifth electrode which is a focus electrode for focusing the electron beam on the screen, and a sixth electrode which is an anode electrode, wherein the electron beam passing hole of the fourth electrode forming the unitary focus lens unit is formed. Is characterized in that the extension is formed in a circular left and right diagonal direction.

In addition, the shape of the extension is preferably formed by combining three straight lines.

Hereinafter, with reference to the accompanying drawings will be described in more detail the configuration and operation of the electron gun for cathode ray tube according to the present invention.

The electron gun of the cathode ray tube according to the present invention includes three cathodes 21, a heater 22 inserted into the cathode 21, a first electrode 23 from the cathode 21, and the second. The electrode 24, the third electrode 25, the fourth electrode 26, the fifth electrodes 27 and 28 constituting the main lens unit and the sixth electrode 29 are arranged to be spaced apart from each other by a predetermined distance.

A feature of the present invention is the unfocused focus consisting of a third electrode 25 and a fifth electrode 27, which are two focusing electrodes, and a fourth electrode 26, which is an acceleration electrode disposed between the third and fifth electrodes. In the lens unit, the shape of the electron beam passing hole of the fourth electrode 26 as the acceleration electrode is improved.

As shown in FIG. 3, the fourth electrode of the conventional cathode ray tube electron gun has a circular electron beam through hole, whereas the fourth electrode of the electron gun according to the present invention has three electron beam through holes as shown in FIG. 4. When the in-line direction of the X-axis and the direction perpendicular to the in-line direction is called the Y-axis, four expansion portions extending from the circular part in the middle of the X-axis and the Y-axis, that is, the diagonal direction, are formed.

Each extension part has a shape formed by combining three straight lines, that is, a quadrangular shape opened toward the center of the electron beam through hole, and a circular part is formed between the extension part and the extension part so as not to adversely affect the electron gun assembly.

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

As shown in FIG. 2, the electron beam accelerated by the potential difference between the cathode 21, the first electrode 23, and the second electrode 24 is located near the center axis of the cathode, and is far from the inner electron beam that proceeds. The generated and traveling external electron beam is configured in the prefocus lens unit so that the internal electron beam passes near the center and the external electron beam passes through the position far from the center. By increasing the intensity of the prefocus lens, the spherical aberration characteristic of the external electron beam passing farther from the center of the lens is greater than that of the inner electron beam passing near the center of the lens, so that the inner electron beam is far from the center of the lens in the main lens section. Allows you to proceed closer to the lens center.

In addition, the third electrode 25, the fourth electrode 26, and the fifth electrode 27, 28 arranged sequentially after the first electrode 23, the second electrode 24, which form the focus lens are respectively. A focus voltage of 6 to 9 Kv, a voltage of 700 to 1000 V, which is the same as that of all the electrodes, and a focus voltage are applied to form a uniform potential lens capable of emitting and focusing an electron beam. However, it is difficult to completely solve the deterioration of the electron beam only with the prefocus lens and the main lens. In addition, as a means for reducing the difference in focus resolution between the center and the periphery of the screen toward a large screen and a high-definition screen, a multi-stage focusing lens is configured to prevent the deterioration of focus due to spherical aberration, but also a halo around the screen. There is a limit to solving the problem.

According to the present invention, an enlarged portion of the electron beam through-hole of the fourth electrode 26, which is the center electrode of the universal potential lens, is formed in the left and right diagonal directions, thereby remarkably reducing the diagonal halo of the electron beam focused on the screen. This can be improved, because part of the electron beam in the diagonal direction is enlarged while passing through an asymmetrical prefocus lens configured for astigmatism and on-screen focus characteristic uniformity, and thus the halo in the vicinity of the spot, in particular in the diagonal direction of the beam. The phenomenon occurs, and serves to suppress the divergence of a portion of the electron beam having a large divergence angle in the diagonal direction while passing through the fourth electrode of the present invention.

Since the shape of the electron beam through holes of the third electrode and the third electrode is circular, the lens has relatively small electric field influences near the diagonal through holes of the fourth electrode compared to the electric field influences in the x and y directions. As the electron beam enters into the unipotential focus lens, the divergence in the diagonal direction is weakened, and the focus is increased in the diagonal direction as it passes through the lens to the fifth electrode. It is possible to make a lens that can significantly reduce the halo phenomenon in the diagonal direction of the electron beam.

As described above, according to the present invention, the shape of the electron beam through hole of the fourth electrode, which is the center electrode forming the unfocused focus lens, in order to improve the focus performance, in particular, to eliminate the halo phenomenon at the periphery of the screen, By constructing a perforated shape of the expanded portion extending in the left and right diagonal directions, the halo phenomenon deteriorated in the diagonal direction of the electron beam can be remarkably eliminated, and the effect of improving the focus performance of the electron gun for a large high resolution cathode ray tube can be obtained.

Until now illustrated and described with respect to the preferred embodiment according to the present invention, but not limited to this can be variously changed and used by those skilled in the art.

However, it is apparent that such modifications fall within the scope of the present invention.

Claims (2)

A triode consisting of a plurality of cathodes emitting an electron beam, a first electrode, and a second electrode for controlling the radiation amount of the electron beam; A unpotential focus lens unit including a third electrode and a fifth electrode as two focusing electrodes and a fourth electrode as an acceleration electrode disposed between the third and fifth electrodes; And a main lens unit including a fifth electrode as a focus electrode and a sixth electrode as an anode electrode for focusing the electron beam on a screen, wherein the electron gun for a cathode ray tube includes: Electron beam through-holes of the fourth electrode forming the unipotential focus lens unit is an electron gun for a cathode ray tube, characterized in that the extension is formed in a circular left and right diagonal direction. The electron gun for a cathode ray tube according to claim 1, wherein the extension part is composed of three straight lines.