KR100617211B1 - electron gun for color cathode ray tube - Google Patents

Abstract

The present invention relates to an electron gun used for a color cathode ray tube or a high-definition industrial monitor, and to improve the resolution at the periphery of the screen by varying the voltage applied to the main lens forming electrode.

To this end, it is provided with a cathode 7 arranged inline toward the fluorescent surface to generate three electron beams, and first and second acceleration and focusing electrodes 12 and 13 for focusing the three electron beams on the fluorescent surface. In the electron gun which applies a static focus voltage to one electrode and a dynamic focus voltage to the other electrode to form a quadrupole lens in a dynamic system for improving focus characteristics at the periphery of the screen. Therefore, an external focus dynamic voltage is applied to the focus electrode A 24 electrically connected to the high voltage electrode 23 through the resistor 25, and an external dynamic voltage without resistance is directly applied to the focus electrode C 26. Alternatively, an external focus dynamic voltage is applied to the focus electrode A 24 through the resistor 25 so as to face the focus electrode A. The focus electrode B 27 constituting the first quadrupole lenses 32 and 34 is applied with a DC electrostatic focus voltage and adjacent to the focus electrode B to form the second quadrupole lenses 33 and 35. C 26 is intended to be directly applied to the dynamic voltage applied from the outside.

Gun, dual quadrupole lens

Description

Electron gun for color cathode ray tube

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

FIG. 2 is a side view cut away of a part of the electron gun applied to FIG. 1; FIG.

3 is a perspective view showing a part of the conventional main lens forming electrode cut away

4 is a front view of a state in which a conventional main lens forming electrode is installed in a neck portion;

5A to 5D are schematic diagrams for explaining paths of electron beams.

6a and 6b is a longitudinal sectional view showing a portion of the electrode applied to the present invention and a perspective view showing a part

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

8A to 8C are diagrams and graphs of an electric AC equivalent circuit in an electron gun formed by a resistor

9A to 9C are schematic views of an equivalent electrostatic lens of the dynamic system used in the present invention and a front view of a screen on which electron beam spots are formed.

Explanation of symbols for main parts of the drawings

7 negative electrode 23 high voltage electrode

24: focus electrode A 25: resistance

26: focus electrode C 27: focus electrode B

32, 34: first quadrupole lens 33, 35: second quadrupole lens

The present invention relates to an electron gun used for a color cathode ray tube or a high-definition industrial monitor. More specifically, an electron gun for a color cathode ray tube that improves resolution at a peripheral portion of a screen by varying a voltage applied to a main lens forming electrode. It is about.

1 is a cross-sectional view of a typical color cathode ray tube, the structure of which is as follows.

A panel 1 coated with red, green, and blue fluorescent materials on an inner side thereof, a shadow mask 3 installed adjacent to an inner side of the panel to serve as color screening of the electron beam 2, and a A funnel 4 fixed to the rear, an electron gun 5 mounted on the neck portion 4a of the funnel to scan the electron beam 2 to the screen side, and an electron beam installed on the outer circumferential surface of the neck portion and vertically emitted from the electron gun Or a deflection yoke 6 or the like for deflecting in the horizontal direction.

Each electrode of the electron gun 5 applied to the cathode ray tube is in-line perpendicular to the path through which the electron beam passes so that the electron beam 2 generated at the cathode can be controlled to a constant intensity and reach the screen. Is placed.

The structure of the electron gun 5 will be described in more detail with reference to FIG. 2.

Three cathodes 7 each having a heater embedded therein and arranged horizontally side by side independently of each other, a first grid electrode 8 arranged to maintain a predetermined distance from the cathode to control hot electrons generated at the cathode, and the first The second grid electrode 9 and the third grid electrode which are arranged to maintain a predetermined distance from the first grid electrode and serve to pull out and accelerate the hot electrons collected on the surface of the electron-emitting material of the cathode 7 (not shown). 10, the fourth grid electrode 11, the fifth grid electrode 12, and the sixth grid electrode 13 are sequentially arranged, and the shield cup 14 is disposed on the sixth grid electrode 13. The shield cup is fixed with three BSCs (not shown) which serve to fix the electron gun to the neck while electrically connecting the electron gun 5 and the neck portion 4a. have.

At this time, the electrodes are buried by a pair of bead glass 15, which is a rod-shaped electrical insulator to maintain a predetermined interval.

In addition, three circular electron beam through holes are formed in the electrodes in a direction perpendicular to the traveling direction of the electron beam 2, and these electron beam through holes 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 sixth grid electrode (hereinafter referred to as a "second acceleration and focusing electrode") 13 forming a main lens. The fifth grid electrode (hereinafter referred to as "first acceleration and focusing electrode") 12 is formed to have a non-circular cylinder shape as shown in FIG.

Each of the electron beam through holes 12a, 12b, 12c, 13a, 13b, and 13c formed in the first and second acceleration and focusing electrodes 12 and 13 has a circular shape extending into each electrode. It has a cylindrical side wall of.

The diameter D of each of the electron beam through holes 12a, 12b, 12c, 13a, 13b, and 13c formed in the first and second acceleration and focusing electrodes 12 and 13 is typically 5.5 mm. It is about 5.9 mm, and the space | interval (l) of the said electrodes 12 and 13 is designed to hold about 0.8 mm-1.2 mm.

In addition, electron beam passing holes 12a, 12c, 13a, and 13c, which are positioned at both sides of the electrode and through which the electron electron beams R and B pass, are eccentric to a constant value, but the amount of eccentricity is usually about 0.1 mm to It is about 0.2mm.

When the electron beam 2 is emitted from the cathode 7 of the electron gun 5 configured as described above, the emitted electron beam is accelerated and focused while sequentially passing through each electrode, and then fine pores of the shadow mask 3 installed close to the fluorescent surface. The screen is reproduced because color is screened while passing through and hits the fluorescent surface to emit phosphors.

At this time, the spot where the electron beam 2 hits and emits light (hereinafter referred to as "pixel") serves as a very important factor in determining the resolution of the color cathode ray tube.

In the electron gun of the general color cathode ray tube, there is a problem that the resolution is not good.

That is, one of the major causes of deteriorating the resolution of the color cathode ray tube is a so-called haze phenomenon in which the peripheral portion of the pixel of the electron beam 2 is not clear but emits light dimly.

This phenomenon is due to the influence of spherical aberration and astigmatism directly related to the effective lens diameter of the electrodes 12 and 13 forming the main focusing electrostatic lens. When the haze phenomenon occurs, not only the sharpness of the electron beam pixel is degraded. Since the size of the electron beam spot is increased, the resolution is eventually reduced.

In order to solve the above problem, a dynamic focus system that adjusts the focusing voltage to increase with the deflection angle of the electron beam and weakens the main lens field has been used until now.

However, this system uses pin-cushion and barrel shapes to show the self-converging effect of the horizontal deflection magnetic field distribution and the vertical deflection magnetic field distribution in an inline color cathode ray tube with three electron beam emitters arranged in a straight line along the horizontal scanning direction. Since the electron beam receives the force diverging in the horizontal direction and the focusing force in the vertical direction when scanning the electron beam, the electron beam passing through this portion (deflection field applying portion) causes distortion.

That is, FIG. 5A illustrates an equivalent lens of the dynamic effect appearing at the periphery of the screen. When the dynamic focus system is applied, the vertical electron beam acts in a direction to eliminate the overfocus of the spot as the deflection angle of the electron beam increases. While deflecting in the direction, an optimal combination of the focusing portion of the quadrupole lens 16 and the main lens 17 is maintained.

However, the function of the main lens 17 is uniformly weakened in the vertical direction, and the generation of haze in the vertical direction is compensated by the influence of the diverging lens of the quadrupole lens 16, but in the horizontal direction of the quadrupole lens 16 This results in an increase in the size of the horizontal electron beam spot optimized by the focusing lens effect.

FIG. 5B illustrates a state in which the dual quadrupole lens is applied to improve the problem of increasing the spot size in the horizontal direction as in FIG. 5A.

That is, another incident quadrupole lens (second quadrupole lens) opposite to the existing quadrupole lens direction before entering the above-described conventional quadrupole lens (first quadrupole lens) 16 and the main lens 17 ( 18) increases the horizontal electron beam size when the electron beam is incident on the final main lens 17, thereby reducing the horizontal electron beam size at the periphery of the screen past the deflection magnetic field 19 by the deflection yoke 6 have.

However, the effect of improving the horizontal size of the electron beam at the periphery of the screen using the dual quadrupole lenses 16 and 18 is not significantly improved compared to the theoretical background.

This is to increase the divergence angle of the electron beam and the size of the electron beam in the lens part due to the horizontal divergence effect among the dual quadrupole lenses 16 and 18 in the horizontal direction. This is because, when passing through the second quadrupole lens 18 and passing through the first quadrupole lens 16, it passes through another focusing lens and thus its action is halved.

As a result, when this electron beam is deflected to the periphery, the asstigmatism 20 is increased in the main lens as shown in FIG. 5D to remove the horizontal focusing lens at the front end of the main lens 17, and the periphery of the screen. In Esau, all dual quadrupole lenses are disappearing.

As a result, a method of reducing the spot size in the horizontal direction at the periphery of the screen is mainly adopted by applying the dual quadrupole lens 21 and 22 in which the size of the lens is inverted at the center of the screen as shown in FIG. 5C.

However, the electron gun using the above methods still results in a drop in resolution since the electron beam is severely distorted at the periphery of the screen, and thus the electron beam has a heavily lateralized spot shape.

The present invention has been made to solve such a problem in the prior art, by applying a dynamic voltage having a different amplitude to each of the focus electrodes forming the double quadrupole lens to improve the uniformity of the focus across the front of the screen, Its purpose is to be good.

According to an aspect of the present invention for achieving the above object, there is provided a cathode arranged inline toward the fluorescent surface to generate three electron beams, and first and second acceleration and focusing electrodes for focusing the three electron beams on the fluorescent surface. In the electron gun which applies the static focus voltage to one electrode and the dynamic focus voltage to the other electrode to form a quadrupole lens in a dynamic system for improving the focus characteristic at the periphery of the screen, the focus electrode is divided into a plurality of electron guns. An electron gun for a color cathode ray tube is provided, wherein an external focus dynamic voltage is applied through a resistor to a focus electrode A which is electrically independent of the high voltage side, and an external dynamic voltage is applied directly to the focus electrode C without a resistance. .

According to another aspect of the present invention, there is provided a cathode arranged in an inline direction toward a fluorescent surface to generate three electron beams, and first and second acceleration and focusing electrodes for focusing the three electron beams on the fluorescent surface. In an electron gun in which a static focus voltage is applied to one electrode and a dynamic focus voltage is applied to another electrode to form a quadrupole lens in a dynamic system for improving characteristics, an external focus dynamic voltage is applied to the focus electrode A. The focus electrode B, which is applied through the second electrode and the focus electrode B, which is applied to the focus electrode A, is applied to the focus electrode C and is adjacent to the focus electrode B. Electron gun for color cathode ray tube, characterized in that the applied dynamic voltage is directly applied It is provided.

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

6A and 6B are a perspective view showing a longitudinal cross-sectional view and a part of the electrode applied to the present invention, the present invention is installed to face the existing high voltage electrode 23 as shown in Figure 6a to form a main lens The dynamic voltage is applied to the focus electrode A 24 through a predetermined resistor 25, so that the modified dynamic voltage is reduced by approximately 50% from the amplitude of the dynamic voltage actually applied.

A focus electrode B 27 to which a static focus voltage is applied is positioned between the focus electrode A 24 and a focus electrode C 26 to which a dynamic voltage is directly applied.

FIG. 6B illustrates the shape of an electrode for forming a second quadrupole lens formed between focus electrode A 24 and focus electrode B 27, or between focus electrode B 27 and focus electrode C 26. will be.

The voltage waveforms applied to the respective focus electrodes are shown in FIG. 7.

The frequency of the waveform is a frequency synchronous with the horizontal and vertical frequencies applied to the deflection yoke coil, with the peak of the AC waveform representing the perimeter 28 of the screen, and the minimum representing the center of the screen.

As described above, the static voltage level 29 of the focus electrode B 27 is designed to be positioned at an intermediate level of the dynamic voltage synchronized with the horizontal frequency, and the focus electrode A 24 passing through the resistor 25 is formed around the screen. It is designed to clamp with static voltage at.

In addition, the voltage level 30 of the focus electrode C 26 allows a dynamic voltage applied to the outside to be directly applied.

The principle of the resistor used for AC voltage reduction applied in the present invention is as follows.

8A shows an AC equivalent circuit diagram formed in the electron gun through the resistor.

Equation 1 is a dynamic voltage reduction phenomenon is formulated using the equivalent circuit, and when the input voltage (Vi) is the AC dynamic voltage applied from the outside, the induced voltage 31 of the focus electrode A (24) is derived. One formula.

8B and 8C show the induced voltage characteristics according to the change of the resistance value connected with the parasitic capacitance between the electrodes by using Equation 1 above.

The parasitic capacitance is typically less than 10pF and when the resistance is set to R> 10MΩ or more, it can be seen that the induced voltage of the focus electrode A 24 connected through the resistor is 50% of the external input voltage.

In addition, it can be seen through the equation that the movement of the face φ is also less than 10 °.

When the externally applied dynamic voltage is Vd = Vmexp (jwt),

FIG. 7 illustrates voltage levels and waveforms to be applied to the respective focus electrodes, and equivalent models of the electrostatic lenses generated between the electrodes are shown in FIGS. 9A and 9B.

In the center of the screen, a strong first quadrupole lens 32 and a second quadrupole lens 33 are formed as shown in FIG. 9A. In particular, the first quadrupole lens facing the main lens causes the electron beam to be strongly focused in the vertical direction. In the horizontal direction, a strong diverging lens is formed, thereby forming a central electron beam spot in a circular shape.

However, unlike in the center, as shown in FIG. 9B, at the periphery of the screen, the strong first quadrupole lens 34 disappears and the second quadrupole lens 35 for emitting an electron beam as a lens type can improve the horizontal spot size of the periphery. Directly opposite the main lens.

This is because the voltage level of the focus electrode A 24 applied through the resistor is clamped with the static voltage level at the periphery of the screen as in the focus voltage level shown in FIG. 7.

As such, the configuration of the electrostatic lens at the center and the periphery of the screen may define the spot improvement effect through the formula of the magnification definition of Equation 2.

Where M is the magnification

       A: main lens incident angle of the electron beam

       B: main lens divergence angle of the electron beam

       Vb: anode voltage

       Vf: Focus voltage

In the conventional electron gun structure, the horizontal main lens divergence angle Bh 36 at the periphery of the screen is smaller than the vertical divergence angle Bv 37 so that the magnification in the horizontal direction is relatively higher than in the vertical direction.

In addition, in the conventional structure of the improved multi-quadrupole lens, since the electron beam is focused at the peripheral part after passing the two-stage lens in the horizontal direction and divergence, it is impossible to form a sufficient horizontal divergence angle, such as Mh> My. As the effect is maintained, the optimum spot shape at the periphery of the screen still forms a transverse spot 38 as shown in FIG. 9C.

However, in the present invention, since the first quadrupole lens 34 is reduced and extinguished at the periphery of the screen, the main lens is directly opposed to the second quadrupole lens 35, that is, the diverging lens, so that the above-mentioned problem can be solved in the horizontal direction. The main lens divergence angle Bh of 36 is sufficiently made large.

Therefore, since the main lens divergence angle in the horizontal direction and the main lens divergence angle in the vertical direction can be almost coincided, Mh ≒ My can be realized as a result. It will be able to implement a circular spot 39 of the same shape as.

As described above, according to the present invention, since different voltages are applied to the focus electrode according to the electrode structure and the electrode connection form of the electron gun, the deterioration characteristic of the electron beam scanned to the screen is eliminated, thereby improving the resolution over the entire area of the screen. It can be improved uniformly.

Claims (5)

The focus electrode A is divided into a plurality of focus electrodes, and an external focus dynamic voltage is applied to the focus electrode A that is electrically independent of the high voltage side, and the focus electrode C is disposed to face the focus electrode A so that a predetermined distance is maintained. In the electron gun for color cathode ray tube to which an external dynamic voltage without resistance is directly applied, An electron gun for a color cathode ray tube, characterized in that a static focus voltage is directly connected to the focus electrode B by providing a focus electrode B between the focus electrodes A and C to form a dual quadrupole lens. delete delete In a dynamic system for improving the focus characteristic at the periphery of the screen and having a cathode disposed inline toward the fluorescent surface to generate three electron beams, and the first and second acceleration and focusing electrodes for focusing the three electron beams on the fluorescent surface In the electron gun applying a static focus voltage to one electrode and a dynamic focus voltage to the other electrode to form a quadrupole lens, An external focus dynamic voltage is applied to the focus electrode A through a resistor, and a DC electrostatic focus voltage is applied to the focus electrode B which is disposed to face the focus electrode A and constitutes the first quadrupole lens. An electron gun for a color cathode ray tube, characterized in that a dynamic voltage applied from the outside is directly applied to a focus electrode C which is disposed adjacent to constitute a second quadrupole lens. The method of claim 4, wherein The static focus voltage level (Vsf) for constituting the dual quadrupole lens is the relationship between the external dynamic voltage (VDf + Vdf) and V _Sf = V _Df + ΔV _{vdf (max)} + (ΔV _{hdf (max)} ) / 2 Electron gun for color cathode ray tube characterized in that it has a. ΔV _{hdf (max)} : Horizontal dynamic AC maximum voltage ΔV _{vdf (max)} : Vertical dynamic AC maximum voltage

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