KR19990070795A - Electron gun for colored cathode ray tube - Google Patents

Abstract

The present invention is an improvement of the structure of the electrostatic field control electrode body installed inside the main lens forming electrode to form a good beam spot on the screen, the cathode 8 and the electron beam emitted from the cathode Focusing on the screen on which the phosphor is coated, a prefocus lens forming electrode consisting of a triode comprising two or more electrodes for controlling and accelerating, two or more electrodes serving to focus the electron beam, and a controlled and accelerated electron beam; The main lens unit forming electrodes composed of two or more electrodes serving to focus and accelerate to form are sequentially arranged in the tube axis direction, and the corners are rounded inside the common openings formed on opposite surfaces of the main lens unit forming electrodes. In the electron gun which is provided with the electrostatic field control electrode bodies 16 and 17 in which the square-shaped electron beam passing holes 16a and 17a are formed, The electrostatic field in which the corner radius a of the electron beam through hole 16a of the electrostatic field control electrode body 16 fixed in the electrode close to the prefocus forming electrode is fixed inside the remaining main lens forming electrode. Since it is formed larger than the radius b of the corner portion of the electron beam through hole 17a of the long control electrode body 17, the shape of the beam spot generated by the non-axisymmetric geometry is improved.

Description

Electron gun for colored cathode ray tube

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for color cathode ray tubes, and more particularly to a structure of an electrostatic field control electrode body provided inside a main lens forming electrode in order to form a good beam spot on a screen.

As shown in FIG. 1, a general color cathode ray tube includes a panel 1 in which phosphors 2 are coated in a dot or stripe type on the inner surface thereof, and a funnel 3 fused by the panel and bead glass. A shadow mask which is formed integrally with the funnel and has a neck portion 3a in which an electron gun 4 is enclosed, and is installed at a position proximate to the phosphor coated on the panel, and serves as color screening of the electron beam scanned from the electron gun ( 5) and a deflection yoke 7 or the like provided on the interface between the funnel and the neck portion to deflect the electron beam 6 scanned from the electron gun over the entire area of the screen.

FIG. 2 is a longitudinal cross-sectional view and a cross-sectional view illustrating an embodiment of a BPF type electron gun of an in-line type electron gun used in a general color cathode ray tube as shown in FIG. 1.

When the heater 9 embedded in the cathode 8 of the electron gun receives power from the stem pin 10 and generates heat, hot electrons are radiated from the cathode 8 by heat generated by the heater.

The radiated hot electrons, that is, the electron beam 6, reach the screen through a plurality of electrode holes provided at regular intervals vertically from the cathode 8 to the screen side.

Hereinafter, the process in which the electron beam 6 starting from the cathode 8 reaches the screen will be described in detail.

The electron beam 6 emitted from the cathode 8 of the electron gun 4 is controlled and accelerated by the first grid 11 and the second grid 12, which are the control electrodes forming the triode, and the second grid and the third grid. Since the pre-focus lens forming electrode formed between the grid 13 and the main lens forming electrode formed between the third grid 13 and the fourth grid 14 are sequentially passed, they are focused and accelerated.

The electron beam passing through the bi-potential electrostatic lens, which is the main lens of the electron gun, is affected by the magnetic field formed according to the strength of the electric current applied to the deflection yoke 7 surrounding the lower end portion of the funnel 3. Is determined.

Accordingly, the electron beam is blown through the holes of the shadow mask 5 provided in proximity to the phosphor 2 along the path determined by the intensity of the current applied to the deflection yoke 7, so that the screen is reproduced.

The electron gun operating as described above has an outer beam (electron beam implementing red and blue) at the electrode constituting the electrostatic lens so that the three electron beams 6 representing red, green, and blue coincide at the center of the screen. The electrostatic lens is formed so as to offset the passing electron beam through hole, or in another suitable way, to direct the path of the outer beam toward the center beam (electron beam for green).

The self-convergence deflection yoke (7) is used to match three electron beams (6), red, green, and blue, in the inline electron gun. Pin-cushion in the horizontal direction and a barrel magnetic field in the vertical direction.

Therefore, in the color cathode ray tube adopting the self-convergence deflection yoke 7, the three electron beams coincide over the entire area of the screen due to the formation of the above magnetic field.

At this time, each of the red, green, and blue electron beams 6 diverges in the horizontal direction and receives a focusing force in the vertical direction, but is halo in the vertical direction by the geometry of the panel 1. This is a phenomenon.

Therefore, in order to eliminate the phenomenon that the astigmatism increases in the negative direction, the asymmetry of the electron gun is formed asymmetrically so that the astigmatism takes a positive value in the center of the screen. Although the astigmatism value at the periphery of the screen is negative, the absolute value is reduced so that the resolution is improved in all areas of the screen.

The size of the main lens formed by the voltage difference between the third and fourth grids 13 and 14 used to make the red, green, and blue electron beams 6 form a small spot on the screen depends on the diameter of the neck portion. do.

The larger the size of the electron beam passing holes facing each other of the third and fourth grids 13 and 14 forming the main lens through which the red, green, and blue electron beams 6 pass, the smaller the spots are formed on the screen. It is a well known fact.

This is because spherical aberration and magnification are reduced.

In general, the inline electron gun passes through the electron beam through-holes formed in the third and fourth grids 13 and 14 along the inside of the neck portion.

Accordingly, as shown in FIG. 3, the three independent main lenses through which the red, green, and blue electron beams 6 pass are retracted to increase the size of the substantial main lens.

This structure has the advantage of obtaining a smaller beam spot on the screen because it can reduce spherical aberration and reduce magnification of the lens.

In addition, as shown in FIG. 3, the astigmatism generated when the self-convergence deflection yoke 7 is used by providing the correction electrode 15 in the fourth grid 14 is corrected.

That is, astigmatism can be corrected by raising the just focus voltage in the horizontal direction and the just focus voltage in the vertical direction.

As shown in FIG. 4, the rectangular electron beam through holes 16a and 17a formed in the electrostatic field control electrode bodies 16 and 17 have a relatively long length in the diagonal direction compared to the horizontal and vertical lengths. The same beam spot is formed, Figure 5 shows the simulation results.

That is, since the just focus voltage is the lowest in the diagonal direction of the beam spot, the size of the beam spot is increased in the diagonal direction, resulting in deterioration of resolution.

The present invention has been made to solve such a problem in the prior art, and can improve the resolution of the beam spot generated by the asymmetrical geometry used to form a larger main lens, thereby obtaining a further improved resolution. The purpose is to make it.

According to an aspect of the present invention for achieving the above object, a three-pole portion consisting of a cathode to which electrons are emitted, two or more electrodes for controlling and accelerating the electron beam emitted from the cathode, and two to serve to focus the electron beam partially The main lens unit forming electrode consisting of a prefocus lens forming electrode composed of two or more electrodes and two or more electrodes serving to focus and accelerate the focused and accelerated electron beam to focus on a screen coated with a phosphor. In the electron gun arranged in order to install an electrostatic field control electrode body formed with a rectangular electron beam through hole rounded corners inside the common opening formed on the mutually opposite surfaces of the main lens portion forming electrode, the main lens portion Among the formation electrodes, the electrostatic field control electrode body fixed inside the electrode close to the prefocus lens forming electrode side An electron gun for a color cathode ray tube is provided, characterized in that the radius of the electron beam through hole corner portion is larger than the radius of the electron beam through hole corner portion of the electrostatic field control electrode body fixed inside the remaining main lens portion forming electrode.

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

Figure 2 is a longitudinal sectional view and a cross-sectional view showing an embodiment of a conventional in-line BPF type electron gun

Figure 3 is a longitudinal sectional view and a cross-sectional view showing another embodiment of a conventional in-line BPF type electron gun

4 is a front view illustrating each of the electrostatic field control electrode bodies applied to FIG. 3.

FIG. 5 is a beam spot diagram formed by the electron gun of FIG. 3. FIG.

Figure 6 is a front view showing each of the electrostatic field control electrode body applied to the present invention

7 is a beam spot diagram formed by the present invention.

Explanation of symbols for main parts of the drawings

8 cathode 11 first grid

12: second grid 13: third grid

14: fourth grid 16, 17: electrostatic field control electrode body

16a, 17a: electron beam through hole

Hereinafter, the present invention will be described in more detail with reference to FIGS. 6 and 7.

FIG. 6 is a front view showing an electrostatic field control electrode body according to the present invention, and FIG. 7 is a beam spot diagram formed by the present invention, and the same parts as those of the conventional electron gun configuration of the present invention will be omitted. The same reference numerals will be given.

According to the present invention, a three-pole portion and a prefocus lens forming electrode are formed of a cathode 8 to which electrons are emitted, and a first grid 11 and a second grid 12 to control and accelerate the electron beam 6 emitted from the cathode. And main lens forming electrodes constituting a bi-type lens for properly focusing and accelerating so as to focus on the screen on which the phosphor is applied are sequentially arranged in the tube axis direction.

In the present invention, the main lens forming electrodes are described as the third and fourth grids 13 and 14 for convenience, but the present invention is not limited thereto.

The reason for this is that the prefocus lens forming electrode and the main lens forming electrode can each be composed of two or more, and in this case, the present invention is also applicable.

Opposite surfaces of the third and fourth grids 13 and 14 serve as common openings through which the electron beam 6 passes, and electrostatic field control electrode bodies 16 and 17 are provided inside the common openings, respectively. have.

At this time, the corner radius a of the electron beam through hole 16a formed in the electrostatic field control electrode body 16 is the electron beam through hole 17a of the electrostatic field control electrode body 17 installed in the fourth grid 14. It is set larger than the corner radius b of ().

The main lens formed by the above-described structure includes the electrostatic field control electrode body 16 of the third grid 13, the electrostatic field control electrode body 17 of the fourth grid 14, and the correction electrode 15. The strength and aberration of the third and fourth grids 13 and 14 are determined by opposing common openings.

The main lens is constructed by the structure and dimensions of the electrostatic field control electrode body 16 and the third and fourth grids 13 and 14 having the shapes shown in FIG. 4 provided in the third and fourth grids 13 and 14. When the negative astigmatism has a negative astigmatism, the correction electrode 15 in the fourth grid 14 has a positive astigmatism.

However, the electrostatic field control electrode bodies 16 and 17 having the shape as shown in FIG. 4 have the lowest edge voltages (a) and (b) of the electron beam through holes 16a and 17a, so that the electron beam just focus voltage in the diagonal direction is the lowest. do.

That is, focusing in the diagonal direction is the weakest, so that the beam size in the diagonal direction on the screen is the largest as shown in FIG. 5.

Accordingly, the corner radius a of the electron beam passing hole 16a of the electrostatic field control electrode body 16 provided in the third grid 13 passes through the electron beam of the electrostatic field control electrode body 17 provided in the fourth grid 14. By making the electron beam focusing effect in the diagonal direction larger than the corner radius b of the ball 17a, the just focus voltage in the diagonal direction becomes smaller than the just focus voltage in the horizontal direction, and the just focus voltage in the vertical direction. As it becomes larger, the conventional beam spot shape is improved.

FIG. 7 illustrates simulation results of beam spots appearing on the screen according to the shape of the electrostatic field control electrode body 16 as shown in FIG. 6.

As described above, the present invention improves the shape of the electron beam through hole 16a of the electrostatic field control electrode body 16 installed in the third grid 13 to improve the shape of the beam spot generated by the non-axisymmetric geometry. As a result, an improved resolution is obtained.

Claims (1)

A pre-focus lens forming electrode comprising a three-pole portion consisting of a cathode to which electrons are emitted, two or more electrodes for controlling and accelerating the electron beam emitted from the cathode, two or more electrodes to partially focus the electron beam, and control And arranging main lens portion forming electrodes composed of two or more electrodes to focus and accelerate the accelerated electron beam to focus on a screen coated with phosphors in a tube axis direction. An electron gun configured to install an electrostatic field control electrode body having a rectangular electron beam through-hole having rounded corners inside the common opening formed on the opposite surface, the electrode closer to the prefocus lens forming electrode among the main lens forming electrodes. The main lens part has a radius of the corner of the electron beam through hole of the electrostatic field control electrode fixed inside. Property sheet of the electrostatic control electrode member fixed to the inside of the electrode beam passing holes edge color cathode-ray tubes the electron gun, characterized in that part is larger than the radius of.