KR200354649Y1 - electron gun for color cathode ray tube - Google Patents

Abstract

The present invention relates to an electron gun for a color cathode ray tube, which reduces the size of the main lens electrode in an electron gun having a large-diameter main lens that reduces the spot diameter on the screen to improve the focus on the screen by enlarging the main lens diameter. It is possible to realize a uniform resolution by improving characteristics and reducing dispersion.

The present invention forms a plurality of grooves in a direction transverse to the longitudinal direction of the ceiling surface on the ceiling surface of the rim portion, which is the opposite surface of the electrode, in an electron gun having a forks electrode constituting the main lens and a rim having a single opening throughout the anode. In addition, the groove portion is formed along the longitudinal direction of the ceiling surface to suppress the long and short diameter changes during the electron gun manufacturing process as much as possible.

Description

Electron gun for color cathode ray tube

The present invention relates to an electron gun for a color cathode ray tube, and in particular, a spot diameter on a screen through an enlargement of the main lens mirror according to the need to improve the focus on the screen due to the use of high definition and high frequency. In the electron gun having a large-diameter main lens of the type to reduce the focus to improve the focus on the screen, it is possible to suppress the dimensional change of the main lens electrode to achieve a uniform resolution by improving the resolution characteristics and reduction of the dispersion.

The inline electron gun for the color cathode ray tube includes three independent cathodes 1 as shown in FIG. 1, a first electrode 3 disposed at a predetermined distance from the cathode and a common lattice of the cathode, and at a predetermined interval from the first electrode. The second and fourth electrodes 4, 5, 6, 5, 7, and 6, and a shield cup disposed on the sixth electrode. 9) and the like.

Therefore, when electrons are emitted by the heat generated by the heater 2 embedded in the cathode 1, the electrons are controlled by the first electrode 3, which is a control electrode, and the second electrode 4, which is an acceleration electrode, is controlled. The electron beam is accelerated, and a part of the electron beam is focused and accelerated by the shear focusing lens formed between the second electrode, the third electrode 5, the fourth electrode 6, and the fifth electrode 7.

On the other hand, the main lens forming electrode is made of a fifth electrode 7 (hereinafter referred to as "focus electrode") called a focus electrode and a sixth electrode 8 (hereinafter referred to as "anode electrode") called an anode electrode, The main lens forming electrode performs a main focusing and accelerating function of the electron beam so that the electron beam passes through the shadow mask 12 installed on the inner surface of the fluorescent surface 13 and then collides with the screen 14 to emit light.

A deflection yoke 10 is provided outside the electron gun to deflect the electron beam emitted from the electron gun to the entire screen 14.

Important factors influencing the spot diameter on the screen in the design of the electron gun include the magnification of the lens, the space charge repulsion force, and the spherical aberration characteristics of the main lens. Among them, the influence of the spot diameter (Dx) due to the lens magnification Since the basic voltage condition, focal length and electron gun length are determined, there are few parts that can be used as a design element and its effect is insignificant.

In addition, 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 repulsive force, the divergence angle α, which is the angle at which the electron beam proceeds, may be increased. It is advantageous to design it.

On the other hand, the spherical aberration characteristic of the main lens refers to the magnification 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 circular axis. Contrary to the space charge repulsion force, the smaller the divergence angle at which the electron beam is incident on the main lens, the smaller the spot diameter can be realized on the screen.

Considering the above design factors, the spot diameter Dt on the screen is the sum of three factors. It is expressed as

In particular, as the best way to reduce spherical aberration while reducing the space charge repulsion, a method of reducing the magnification of the spot caused by spherical aberration is attempted even if an electron beam with a large divergence angle is incident by expanding the main lens diameter. The space charge repulsion after passing can also be reduced, enabling small spots on the screen.

5 is a graph showing the change of the spot diameter according to the change of the main lens diameter as an experimental result showing the above contents.

As can be seen from the graph, the larger the main lens diameter, the smaller the magnification of the spot diameter due to the spherical aberration of the main lens, so that the spot diameter can be reduced on the screen.

Fig. 2 is a partially broken perspective view of a main lens portion showing an example of a conventional electron gun, in which a race track shape common to three electron beams serving as opposing surfaces of the focus electrode 7 and the anode electrode constituting the main lens is shown in FIG. The (Rim) portions 7a and 8a are recessed into the electrodes, and three electron beam through holes 17 and 18 are formed in the planes 15 and 16 of the depressions.

This type of main lens can enlarge the pore diameter compared to the conventional electron gun having only three electron beam passing holes, thereby obtaining the effect of enlarging the main lens diameter, but the effect of the lens on the three electron beams There is a problem in that the action of the lens and the horizontal is weaker than the vertical.

Therefore, in order to compensate for this, the electrostatic field control electrode body having three holes should be installed inside the rim to adjust the horizontal and vertical focusing actions almost equally while matching the action of the lens to the electron beam.

Fig. 3 is a broken perspective view of the main lens portion showing another example of a conventional electron gun, in which rim portions 7b and 8b are common to three electron beams on opposite surfaces of the focus electrode 7 and the anode electrode 8, and the rim portion The electrostatic field control electrode bodies 19 and 20 are formed in the center formed by retreating into the electrode by a predetermined interval in the form of a flat electrode having elliptical holes in the center and semi-elliptical holes on both sides. Like 2, the main lens can be enlarged.

A correction electrode 21 is attached to a lower end of the shield cup 9 electrically connected to the anode electrode 7 to finely adjust the astigmatism characteristic, which is a difference between the horizontal and vertical focusing force of the electron beam.

4 is a partially broken perspective view of the main lens portion showing another example of the conventional electron gun, which projects from the center of the bottom of the cup-shaped electrode and the bottom of the shield cup 9 having a rim common to the three electron beams, and has one ball in the center; There is a protruding piece 22 with 23, and the protruding piece 22 serves as the electrostatic field control electrode body of the main lens.

The focus electrode 7 facing the anode electrode 8 has the same shape as a conventional main lens, and has a cup-shaped electrode having a single rim portion 7c and a plate-shaped electrode having three electron beam through holes 25 formed therein. Of the electrostatic field control electrode body 24. In order to deepen the distance from the rim of the electrostatic field control electrode body to the electrostatic field control electrode body for the expansion of the main lens mirror, the anode electrode 8 is formed of a conventional rim and its The plate-shaped electrostatic field control electrode body having three electron beam through holes 27 and rim 8c having one ball common to three electron beams and not located in the shape of the rim but located apart from the rim 8c. It consists of 26.

However, the electron gun as shown in FIGS. 3 and 4 has an independent rim, so that the height of the electrode of the depression can be easily changed in the design for improving the resolution of the screen, and thus is advantageous for the design of the electron gun for better characteristics. In order to enlarge the main lens diameter, the long and short diameters of the rim are large. Therefore, the size of the long and short diameters is severely changed due to thermal change during the assembly process of the electron gun and stress caused by polishing, welding or beading. there is a problem.

In other words, the electrode having a rim is usually in the form of a cup, and a metal plate having a thickness of about 0.3 mm to 0.4 mm is used as a raw material, so that the amount of change in the long diameter and the short diameter changes to 15 µm to 30 µm.

In general, long and short diameter component tolerance is managed to ± 10㎛ in the electrode having a rim. As described above, a large number of components out of the tolerance range are generated, and such large changes are optimally adjusted for the center electron beam and the side electron beam. Not only does it cause a difference in the regulation voltage, but also adversely affects the difference in the vertical and horizontal focusing voltages and the alignment characteristics of the electron beam.

6 is a graph showing the tendency of the optimal focusing voltage in the vertical direction when there is a dimensional change from the center value of the short diameter of the electrode.

Therefore, there is a problem that a problem occurs in the overall resolution characteristics of the screen, or the resolution distribution between lots or within a lot becomes large.

An object of the present invention is to provide an electron gun for a color cathode ray tube that can suppress the change in the long and short diameter during the process of assembling the electron gun in the cup-shaped electrode having a rim.

In accordance with an embodiment of the present invention for achieving the above object, there is provided an electron gun for a color cathode ray tube in which a groove is formed on an opening surface on which a rim of a rim electrode is formed in a rim electrode having a single opening of an electron gun.

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

2 is a partially broken perspective view of a main lens part showing an example of a conventional electron gun;

3 is a partially broken perspective view of a main lens portion showing another example of a conventional electron gun;

4 is a partially broken perspective view of a main lens portion showing still another example of a conventional electron gun;

5 is a graph showing the change of the spot diameter according to the main lens diameter in the electron gun

6 is a graph showing a change in characteristics according to the change in size of the short diameter of the electrode

7 is a partial perspective view showing an example of the main lens electrode of the electron gun according to the present invention

8 is a partial perspective view showing another example of the main lens electrode of the electron gun according to the present invention

Explanation of symbols for main parts of the drawings

7: focus electrode 7c: rim

8 anode electrode 8c rim

28: ceiling top 29: groove

30: groove

7 and 8 are perspective views showing the main lens electrode of the electron gun according to the present invention.

As shown in FIG. 7, the focus electrode 7 and the anode electrode 8 are formed at the rim portions 7c and 8c having a single opening common to the three electron beams formed on the focus electrode 7 and the anode electrode 8 forming the main lens. At least one recess is formed on the ceiling surface 28.

The recess 29 is formed at a position that does not coincide with the centers of the three electron beam through holes, and a plurality of recesses 29 are formed according to the size and shape of the electrode so as to suppress the dimensional deformation of the rim of the cup as much as possible.

In addition, the recess 29 is formed in a direction transverse to the longitudinal direction of the ceiling surface.

FIG. 8 illustrates another embodiment of the present invention, in which a groove 30 is formed along the circumference of the rim on the ceiling surface 28, which is the opposite surface of the focus electrode 7 and the anode electrode 8. ) May be formed over the entire circumference of the rim or partially formed along the rim of the rim.

In addition, the depth of the groove portion 29 and the groove portion 30 is preferably less than the material thickness of the electrode in order to minimize the effect on the screen resolution, but may be more than the material thickness of the electrode when the resolution is not affected. .

Electrode of the electron gun according to the present invention is that the groove portion 29 or the groove portion 30 formed on the ceiling surface of the rim portion forming the main lens absorbs the stress due to thermal changes, polishing and welding, beading, etc. during the electron gun assembly process and Since it is blocked, the maximum and short diameter changes of the cup can be suppressed to the maximum.

For example, when the raw material thickness of the electrode is about 0.3 ~ 0.4mm, the long diameter of the electrode is 18mm ~ 19.5mm, and the short diameter is 7.5mm ~ 9.5mm, the change of the long diameter and the short diameter is 15㎛ after the assembly process in the conventional electrode structure. It was about 30㎛ but when forming the recess or groove in the ceiling surface of the rim portion as in the present invention it is possible to reduce the change in the long and short diameter of the cup to about 5㎛ ~ 10㎛.

Claims (4)

In forming a rim having a single opening in a focus electrode and an anode electrode constituting the main lens, An electron gun for a color cathode ray tube, characterized in that a groove is formed on the ceiling surface of the rim portion, which is the opposite surface of the electrode. The method of claim 1, The groove portion is a color cathode ray tube electron gun, characterized in that the plurality of grooves 29 in the direction crossing the longitudinal direction of the ceiling surface of the rim portion. The method of claim 1, The groove portion is a gun for a color cathode ray tube, characterized in that the groove portion formed over the entire length along the longitudinal direction of the ceiling surface of the rim portion. The method of claim 3, wherein Electron gun for the color cathode ray tube, characterized in that a plurality of grooves are formed in a form not connected along the longitudinal direction of the ceiling surface.