KR20010018138A - electron gun for color cathode ray tube - Google Patents

Abstract

PURPOSE: An electron gun for a color cathode-ray tube is provided to improve a focus of an edge portion as well as a center of a screen by inserting an intermediate electrode and using voltages of a focus electrode and an anode electrode. CONSTITUTION: A plurality of cathodes radiate three electron beams in an in-line direction toward a fluorescent surface. A focus electrode(12) and an anode electrode(13) focus the three electron beams on the fluorescent surface. An intermediate electrode(17) is mounted between the focus electrode and the anode electrode for forming a main lens. An exterior voltage which is applied to form a four-electric pole lens is divided into a static voltage and a dynamic voltage. The focus voltage and the anode voltage are distributed and applied to the intermediate electrode(17) through a resistor(18). The focus voltage is supplied again to a dynamic electrode opposed to the intermediate electrode through the resistor.

Description

Electron gun for color cathode ray tube

The present invention relates to an electron gun used for a color cathode ray tube or a high-definition industrial monitor. More specifically, the size of the main lens is improved through a resistor in consideration of spherical and astigmatism of the main lens electrode. The present invention relates to an electron gun connected to a dynamic electrode to adjust an incident angle and a width of an electron beam for each screen position.

1 is a cross-sectional view of a general color cathode ray tube, in which a cathode ray tube is provided with a red, green, and blue fluorescent substance coated on an inner side thereof, and a color of an electron beam 2 provided adjacent to an inner side of the panel. A shadow mask 3 serving as a selection role, a funnel 4 fixed to the rear of the panel, an electron gun 5 mounted on the neck portion 4a of the funnel to scan the electron beam 2 to the screen side, And a deflection yoke 6 provided on the outer circumferential surface of the neck portion for deflecting the electron beam emitted from the electron gun in a vertical or horizontal direction.

Each electrode of the electron gun 5 applied to the cathode ray tube is arranged in-line perpendicular to the path through which the electron beam passes so that the electron beam generated from the cathode can be controlled to a constant intensity and reach the screen.

Referring to this in more detail with reference to FIG. 2, the electron gun 5 includes three cathodes 7 arranged side by side horizontally so that heaters are built-in and independent of each other, and a predetermined distance from the cathode is maintained. A first grid electrode 8 disposed to control hot electrons generated at the cathode, and arranged to be maintained at a predetermined distance from the first grid electrode, and collected on an electron emission material surface (not shown) of the cathode 7. The second grid electrode 9 and the third grid electrode 10, the fourth grid electrode 11, and the plurality of main lens forming electrodes 12 that accelerate and focus the electron beam on the screen, which pulls out and accelerates the hot electrons. (13) are arranged in a line in the tube axis direction, and are buried in a pair of bead glass 14, which is a rod-shaped electrical insulator, and a leakage ruler of the deflection yoke 6 is disposed on the main lens forming electrode farthest from the cathode. There is fixed a shield cup (15) to weaken the shielding.

Three electron beam through holes are formed in each of the electrodes in a direction perpendicular to the traveling direction of the electron beam 2, and the electron beam through holes formed in the electrodes are located on the same plane.

The first grid electrode 8 and the second grid electrode 9 are in the form of a plate and have a main lens forming electrode (hereinafter referred to as an “anode electrode”) 13 to which high pressure is applied and an electrode opposite thereto ( 12 is referred to as a non-circular cylinder shape as shown in FIGS. 3 and 4.

Each electron beam through hole formed in the focus electrode 12 and the anode electrode 13 has a circular cylindrical sidewall extending into each electrode.

The diameter D of the electron beam passing holes of the focus electrode 12 and the anode electrode is usually about 5.5 to 5.9 mm, and the interval l ₁ between the electrodes is set to have a range of 0.8 to 1.2 mm. .

In addition, the outer electron beam passing hole is centered at a constant value, the amount of which is usually about 0.1 to 0.2mm.

The general electron gun configured as described above reproduces the screen by emitting an electron beam and causing the selected fluorescent film 16 to emit light after passing through the shadow mask 3.

At this time, the spot emitted by the electron beam acts as an important factor in determining the resolution.

However, the electron gun of this structure has a limitation in that its characteristics are not good as the resolution of the color cathode ray tube increases.

That is, one of the biggest causes of deteriorating the resolution of the color cathode ray tube is a so-called haze phenomenon in which the peripheral part of the pixel of the electron beam is not clear and emits light faintly.

This phenomenon is due to the influence of spherical aberration and astigmatism directly related to the effective lens diameter of the main lens forming electrodes 12, 13, in which case the sharpness of the electron beam pixel is not only reduced, but also the electron beam spot. Since the size of the becomes larger, the resolution of the color cathode ray tube becomes worse.

In order to solve this problem, a dynamic focus system has been used so far that the focusing voltage increases with the deflection angle of the electron beam, thereby weakening the main lens electric field.

However, this system is an inline type color cathode ray tube with three electron beam emitters arranged in a straight line along the horizontal scanning direction so that the horizontal deflection field and the vertical deflection field distributions have a pin-cushion and barrel shape, respectively. Since each electron beam receives a force diverging in the horizontal direction and a force to focus in the vertical direction, the electron beam passing through this portion is deformed and distorted.

As shown in FIG. 5A, as the deflection angle of the electron beam increases, the vertical electron beam acts in a direction of eliminating the overfocus of the spot while the horizontal electron beam is deflected while the focusing part and the main lens of the quadrupole lens are deflected. Proper formulation of maintains the optimal focusing condition.

However, the function of the main lens is uniformly weakened in the vertical direction, and the haze is compensated for the vertical electron beam by the diverging lens effect of the quadrupole lens. However, the horizontal beam spot is optimized by the influence of the focusing lens of the quadrupole lens. The size increases compared to the central electron beam.

Also, as shown in FIG. 5B, a double quadrupole lens may be used to improve the problem of increasing the spot size in the horizontal direction.

This increases the horizontal electron beam size when the electron beam is incident on the final main lens by adding another quadrupole lens that is opposite to the existing quadrupole lens direction before the electron beam enters the existing quadrupole lens and the main lens side. It is for.

However, when the dual quadrupole lens is used, the improvement of the horizontal size at the periphery of the screen does not have much improved effect compared to the theoretical background.

The second quadrupole lens in the horizontal bipolar lens is intended to increase the divergence angle and beam size of the electron beam in the lens portion due to the horizontal divergence effect, but also when passing the focus lens through the lens. This is because the action is halved while passing through another focusing lens.

As a result, in order to remove the horizontal focusing lens at the front end of the main lens as the electron beam goes to the periphery, asstigmatism is increased in the main lens as shown in FIG. We have adopted a method of reducing the horizontal spot size at the periphery of the screen by using a dual quadrupole lens that reverses the lens size.

However, the electron guns using the above methods still exhibit severe distortion of the electron beam at the periphery of the screen, resulting in a severely stretched spot shape even though the electron beam is optimized.

The present invention has been made to solve such a problem in the prior art, by inserting the intermediate electrode using the voltage of the focus electrode and the anode electrode while applying a dynamic voltage having a different amplitude to the dual quadrupole lens, Its purpose is to improve the focus of the periphery and the center at the same time.

According to an aspect of the present invention for achieving the above object, a plurality of cathodes for emitting an electron beam to scan three electron beams in an inline direction toward the fluorescent surface, and a focus electrode and an anode electrode for focusing the three electron beams on the fluorescent surface And an external voltage applied to form a quadrupole lens in a dynamic system composed of an intermediate electrode disposed between the focus electrode and the anode electrode to improve the electron beam focus at the periphery of the screen to form a main lens. In an electron gun for a color cathode ray tube using a static voltage of 1 and a dynamic voltage, a focus voltage and an anode voltage are divided by a resistor to be applied to an intermediate electrode, and the focus voltage is not directly connected to the intermediate electrode. Connected to the dynamic electrode opposite to the intermediate electrode The color cathode-ray tubes the electron gun, characterized in that to ensure that pressure is applied is provided.

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

FIG. 2 is a side view partially showing the structure of the electron gun applied to FIG. 1; FIG.

3 is a perspective view showing a portion of a conventional focus electrode and an anode cut away

Figure 4 is a front view showing a conventional neck cut

5 is an equivalent electrostatic lens of various dynamic systems used in a general electron gun.

6 is a longitudinal sectional view showing a configuration of the present invention;

7 is a waveform diagram applied to a focus electrode applied to the present invention;

8 is an electric AC equivalent circuit diagram in an electron gun formed by a resistor;

9 is an equivalent electrostatic lens of the dynamic system used in the present invention.

Explanation of symbols for main parts of the drawings

12 focusing electrode 13 anode electrode

17: intermediate electrode 18: resistor

Hereinafter, with reference to Figures 6 to 9 showing an embodiment of the present invention in more detail as follows.

FIG. 6 is a vertical cross-sectional view showing the configuration of the present invention, FIG. 7 is a waveform diagram applied to a focus electrode applied to the present invention, and FIG. 8 is an electric AC equivalent circuit diagram in an electron gun formed by a resistor, and the present invention is shown in FIG. As described above, another intermediate electrode 17 is disposed between the conventional anode electrode 13, which is a high voltage electrode, and a focus electrode forming a main lens therebetween, and a first side of the intermediate electrode is provided as a first electrode. , 2, 3 focus electrodes 12a, 12b, 12c are provided in this order.

The voltage applied to the intermediate electrode 17 is divided into an anode voltage and a focus voltage using a predetermined resistor 18, and then an intermediate voltage of the electrode voltage is applied, and an external dynamic voltage is applied to the third focus electrode 12a. Is applied, and an external static voltage is applied to the second focus electrode 12b.

In addition, the first focus electrode 12a opposite to the intermediate electrode 17 is connected to the first focus electrode 12a by applying a modified dynamic voltage reduced by 50% of the actual external dynamic voltage amplitude.

The voltage waveform applied to the focus electrode according to the above invention is shown in FIG. 7.

The frequency of the waveform is synchronized with the horizontal and vertical frequencies applied to the deflection coils, where the peak point of the AC waveform represents the periphery of the screen and the minimum point represents the center of the screen.

As such, the level of the static voltage of the second focus electrode 12b is positioned at an intermediate level of the dynamic voltage synchronized with the horizontal frequency, and the first focus electrode 12a passing through the resistor 18 is a peripheral portion of the screen. Design to clamp with static voltage at.

In addition, the voltage level of the third focus electrode 12c allows the dynamic voltage applied to the outside to be applied.

The resistance driving principle for reducing the AC voltage applied in the present invention can be described through an equivalent circuit formed between each electrode in FIG. 8A.

That is, when the parasitic capacitance between the electrodes is less than 10pF and the resistance is 10MΩ or more, the induced voltage of the first focus electrode 12a connected through the resistor 18 is 50% of the external input voltage. have.

The externally applied voltage is divided into 1: 1 by the resistor 18 to the intermediate electrode 17 and is always applied as the intermediate voltage between the voltage V2 of the second focus electrode 12b and the anode electrode voltage Eb. do.

Accordingly, since the intermediate voltage between the anode voltage and the focus electrode is applied to the intermediate electrode 17 located in the main lens unit, an equal voltage distribution of the main lens is achieved.

That is, the intermediate electrode 17 is also applied with voltage in synchronization with the external dynamic voltage.

In the related art, since a simple DC voltage divider resistor is used, the sensitivity of the main lens according to the focus voltage is achieved between the intermediate electrode and the focus electrode.

In this case, the change in voltage according to the focus voltage is varied between the focus electrode and the intermediate electrode 17 and the intermediate electrode and the anode electrode 13 so that the degree of freedom in design can be increased. The change in potential difference between the electrode and the intermediate electrode 17 can be reduced, thereby improving the stray.

The role of the resistor 18 connected between the first focusing electrode 12a and the second focusing electrode 12b will be described in more detail as follows.

A first quadrupole lens is formed on the first focusing electrode 12a and the second focusing electrode 12b facing the main lens, and a second quadrupole between the second focusing electrode 12b and the third focusing electrode 12c. The lens is formed.

The first quadrupole lens 19 serves to focus the electron beam strongly in the vertical direction and to diverge strongly in the horizontal direction, thereby forming a central electron beam spot.

However, at the periphery of the screen, the strong first quadrupole lens disappears, and the second quadrupole lens that emits an electron beam is directly opposed to the main lens in the form of a lens capable of improving the spot size in the horizontal direction.

This is understood that the focus voltage level of FIG. 7 is clamped with the static voltage level at the periphery of the screen.

As described above, in the present invention, since the main lens directly faces the diverging lens of the second quadrupole lens, the main lens divergence angle in the horizontal direction is sufficiently large, so that the horizontal divergence angle and the vertical divergence angle of the main lens can be matched as much as possible. As a result, since Mh ≒ Mv is realized, the same spot as the center spot can be realized in the periphery of the screen.

Claims (1)

A plurality of cathodes emitting an electron beam to scan three electron beams in an inline direction toward the fluorescent surface, a focus electrode and an anode electrode for focusing the three electron beams on the fluorescent surface, and the focus electrode and anode to form a main lens In the dynamic system, which is composed of intermediate electrodes installed between the electrodes and applied to improve electron beam focus at the periphery of the screen, the external voltage applied to form the quadrupole lens has one electrostatic voltage and one dynamic voltage. In an electron gun for a cathode ray tube, a focus voltage and an anode voltage are divided by a resistor to be applied to an intermediate electrode, and the focus voltage is not directly connected, but is connected to a dynamic electrode opposite to the intermediate electrode through a resistor to supply a voltage. Color cathode, characterized in that Capacitor gun.