KR100267978B1 - Electron gun for colored cathode ray tube - Google Patents

Abstract

The present invention relates to an electrode structure inside an electron gun that focuses and accelerates an electron beam generated at a cathode to be landed on a phosphor on a screen. The present invention is divided into four focusing electrodes, and a dynamic voltage is applied to the first and third focusing electrodes. The focusing voltage is applied to the four focusing electrodes to form two quadrupole lenses and one focusing lens to reduce the resolution and moiré.

To this end, a triode comprising an electron radiating means for radiating the electron beam 3, a control electrode 12 and an acceleration electrode 13 for controlling the radiation amount of the electron beam and forming a crossover, and a shear focusing forming the electron beam. In an electron gun composed of secondary electrodes and a primary electrostatic focusing lens forming electrode forming a primary electrostatic lens, the focusing electrodes constituting the primary electrostatic focusing lens are divided into four electrodes, and the first, second, third and fourth focusing electrodes ( 27) (28) (29) and (30), and each of the axially asymmetric quadrupoles so that two axially asymmetric quadrupole lenses and one axially symmetrical focus lens are formed between the first focusing electrode and the fourth focusing electrode. A constant voltage is applied to any one of the focusing electrodes forming the lens, a voltage varying in synchronization with the electron beam deflection amount is applied to the remaining electrodes, and at least one of the at least one focusing electrode The electrode has horizontal correction electrodes 33 and 36 and guide inner electrodes 35 and 38 at the poles.

Description

Electron gun for colored cathode ray tube

The present invention relates to a color cathode ray tube, and more particularly, to an electrode structure inside an electron gun which focuses and accelerates an electron beam generated from a cathode to be landed on a phosphor on a screen.

As shown in FIG. 1, a general color cathode ray tube is provided with a panel 1 coated with a red, green, and blue fluorescent surface 2 on an inner surface thereof, and disposed close to the inner surface of the panel, to discriminate color of an electron beam 3. A shadow mask (4) serving, a funnel (5) fixed to the rear of the panel, an electron gun (6) mounted on the neck (5a) of the funnel, and scanning the electron beam (3) to the screen side; It consists of a deflection yoke 7 for deflecting the electron beam emitted from the electron gun in the vertical or horizontal direction.

The stem 8 is fixed to the outside of the electron gun, that is, at the end of the neck portion 5a to be exposed to the outside, so that a voltage is applied to each electrode of the electron gun through a plurality of stem pins 9 fixed to the stem. .

2 is a schematic view showing the structure of a conventional electron gun, wherein the electron gun is composed of a triode and a main lens unit.

The three poles include three cathodes 11 each having a heater 10 embedded therein and arranged horizontally side by side independently of each other, a control electrode 12 disposed to maintain a predetermined distance from the cathode and controlling hot electrons generated from the cathode; The acceleration electrode 13 is arranged to maintain a predetermined distance from the control electrode and serves to pull out and accelerate hot electrons collected on the surface of the electron-emitting material of the cathode (not shown).

The main lens unit is composed of a focusing electrode 14 and an anode 15 for focusing and finally accelerating the electron beam 3 generated in the triode.

The control electrode 12 is grounded, about 500 to 1000 V is applied to the acceleration electrode 13, a high voltage of about 25 to 35 KV is applied to the anode 15, and a positive voltage is applied to the focusing electrode 14. An intermediate voltage of 20 to 35% is applied.

In the conventional electron gun configured as described above, as a predetermined potential is applied to each electrode, an electrostatic lens is formed between them by a potential difference applied to the focusing electrode 14 and the anode 15. Is focused at the center of the fluorescent surface.

At this time, the deflection yoke 7 with horizontal and vertical deflection coils is operated to deflect the electron beam 3 focused on the center of the fluorescent screen 2 in the horizontal or vertical direction of the entire screen, that is, the fluorescent screen. .

In a color cathode ray tube using an inline electron gun, since blue, green, and red phosphors are regularly arranged on a fluorescent surface, magnetic concentration using a non-uniform magnetic field of the deflection yoke 7 to concentrate three electron beams in one of the fluorescent surfaces. The self congress type is applied.

As shown in FIGS. 3A and 3B, the distribution of the magnetic field generated in the deflection yoke 7 to which the self-focusing type is applied is a pin cushion type, and the vertical deflection field is a barrel. The shape prevents misalignment on the fluorescent surface and deflects the electron beam in the horizontal and vertical directions by Fleming's left-hand law.

However, as illustrated in FIGS. 3C and 3D, the above-described horizontal and vertical deflection magnetic fields can be described by dividing into two-pole and four-pole components, which serve to deflect the electron beam in the horizontal and vertical directions. The quadrupole component concentrates the electron beam in the vertical direction and diverges in the horizontal direction, resulting in astigmatism, thereby distorting the electron beam spot.

Even if the magnetic field is close to uniform, the electron beam spot is distorted because of the fine pin cushion and the barrel magnetic component, which causes the electron beam to undergo significant astigmatism at the periphery of the fluorescent surface.

4A and 4B further illustrate the distortion phenomenon of the electron beam spot.

4A and 4B, since the electron beam spot is exactly circular in the center of the screen because it is not influenced by the deflection magnetic field, it is diverged in the horizontal direction as described above, and overconcentrated and distorted in the vertical direction. The high-density horizontal core 16 and its high and low haze 17, which is a phenomenon of low density spreading, are caused to reduce the resolution at the periphery of the screen.

This problem is more severe the larger the cathode ray tube, or the larger the deflection angle.

In order to solve the above problems, there are many methods of correcting astigmatism in synchronization with a deflection signal when the electron beam is deflected to the periphery of the screen. The correction means divides the focusing electrode into two and focuses on the first focusing. The astigmatism is corrected by forming an electrode and a second focusing electrode, and providing a quadrupole lens by providing a separate quadrupole electrode between them.

Referring to the accompanying drawings, astigmatism correction means according to a conventional embodiment is briefly described as follows.

The electron gun of Japanese Patent Laid-Open No. 2-79340 shown in Fig. 5A is composed of a triode portion for generating an electron beam and a focusing electrode for forming a main lens for focusing the electron beam, the focusing electrode being the first focusing electrode 18. The second focusing electrode 19 is divided into two.

The second focusing electrode 19 faces the anode 15 side, and the first focusing electrode 18 faces the second focusing electrode 19.

A long horizontal hole 18a is formed in the first focusing electrode (opposing surface of the second focusing electrode) 18 and a guide inner electrode capable of supporting the first focusing electrode 18 therein. 20) is fixed, and the vertical plate correction electrode 21 is vertically fixed to one side of the guide inner electrode (the opposite surface of the second focusing electrode).

In addition, the horizontal flat plate correction electrode 22 is fixed to one side of the second focusing electrode 19 (the opposite surface of the first focusing electrode) so as to be accommodated in the long hole 18a formed in the first focusing electrode 18. And a quadrupole lens is formed between these electrodes.

The electron gun configured as described above passes through the first and second focusing electrodes 18 and 19 in which the electron beam generated at the three poles is divided into two, and particularly, the quadrupole electrode part (the quadrupole electrode of the first focusing electrode) and the second focusing part. The image is formed on the screen by passing through the quadrupole electrode (hereinafter referred to as "quadrupole electrode") on the electrode 19 and focusing on the main lens.

In particular, when the electron beam is deflected to the periphery, the first focusing electrode voltage (static voltage) is constantly applied, but the second focusing electrode voltage (dynamic voltage) is applied in a state changed according to the amount of deflection of the electron beam, so that it is applied to the quadrupole electrode. This causes the quadrupole lens to operate.

In general, the larger the cathode ray tube or the larger the deflection angle, the higher the voltage is applied to the second focusing electrode than the first focusing electrode.

The second focusing electrode voltage is supplied as a parabola waveform in a circuit of a TV or a monitor. When the voltage is applied to the first focusing electrode, the second focusing electrode voltage is generally about 300 to 1000 V higher than the voltage of the first focusing electrode.

When the second focusing electrode voltage is applied, the quadrupole lens is operated due to the difference between the first focusing electrode voltage and the second focusing electrode voltage, and thus the shape of the electron beam is changed into an elongated shape. It acts in a direction to improve the haze of the peripheral portion generated by the non-uniform magnetic field of the deflection yoke (7).

Hereinafter, the quadrupole lens will be described in more detail.

The deflection yoke 7 serves as a diverging lens 23 for diverging the electron beam in the horizontal direction, and acts as a focusing lens 24 for focusing in the vertical direction, so that the distance difference in the horizontal direction when the electron beam is deflected to the periphery. The over focusing component due to and the under focusing component due to the deflection yoke cancel each other to show a nearly accurate focusing state.

However, in the vertical direction, the overfocusing component due to the distance difference overlaps with the overfocusing component in the vertical direction due to the deflection yoke, resulting in severe overfocusing phenomenon. Appearing, causing resolution degradation at the periphery.

FIG. 8 is an explanatory diagram when a quadrupole lens is applied to improve the spreading of the image at the periphery of a conventional screen, and compensates for deflection yoke astigmatism caused by the quadrupole electrode while maintaining the same focusing force of the main lens. Indicates.

An electron beam having a constant divergence angle α _o at the tripolar portion focuses the horizontal lens 25 of the quadrupole lens in the horizontal direction by the horizontal divergence force by the deflection yoke 7, and in the vertical direction by the deflection yoke. The vertical lens 26 of the quadrupole lens is diverged in the vertical direction by the amount of focusing.

To this end, a main lens weakening component (dynamic voltage) is required, and the main lens weakening component plays a role of focusing at a position of a peripheral portion that requires a matching electron beam in the horizontal and vertical directions.

With such a quadrupole lens and a dynamic voltage, it is possible to have an optimal focusing force at the periphery of the screen.

However, in the conventional electron gun, since the quadrupole lens focuses the electron beam 3 in the horizontal direction and diverges in the vertical direction, the angle α _i of the electron beam 3 incident on the screen is also decreased in the horizontal direction and the vertical direction. 9, the electron beam shape in the periphery of the screen becomes larger in the horizontal direction H, and becomes smaller in the vertical direction V, thereby lowering the horizontal resolution and moiré characteristics.

The present invention has been made to solve such a problem in the prior art, by dividing the focusing electrode into four, applying a dynamic voltage to the first and third focusing electrodes, and applying a focus voltage to the second and fourth focusing electrodes, The purpose is to form a quadrupole lens and one focusing lens to reduce resolution and moiré.

According to an aspect of the present invention for achieving the above object, a three-pole portion consisting of an electron-spinning means for emitting an electron beam, a control electrode and an acceleration electrode for forming the radiation amount control and crossover of the electron beam, and a shear for forming the electron beam In an electron gun consisting of focusing electrode and a capacitive focusing lens forming electrode forming a capacitive lens, the focusing electrode constituting the capacitive focusing lens is divided into four electrodes, and the first, second, three, and four focusing electrodes are sequentially arranged. Any one of the focusing electrodes forming each of the axially asymmetric quadrupole lenses such that two axially asymmetric quadrupole lenses and one axially symmetrical focus lens are formed between the first focusing electrode and the fourth focusing electrode; A constant voltage was applied to the remaining electrodes, and a variable voltage was applied to the remaining electrodes in synchronization with the electron beam deflection. At least one electrode is provided with an electron gun for a color cathode ray tube, characterized in that it is provided with a horizontal correction electrode and a guide inner electrode.

1 is a partial longitudinal cross-sectional view showing a schematic configuration of a general color cathode ray tube;

2 is a schematic view showing the configuration of a conventional electron gun

3A to 3D illustrate distortions of electron beam spots due to non-uniform magnetic field of the self-focusing deflection yoke.

3A is a distribution diagram of a pin cushion type horizontal deflection magnetic field

3b is a distribution diagram of a barrel-type vertical deflection magnetic field;

3C is an exploded explanatory diagram of the dipole and quadrupole components of the pincushioned horizontal deflection magnetic field;

3D is an exploded explanatory diagram of the dipole and quadrupole components of the barrel-type vertical deflection magnetic field;

Figure 4a is a view showing the shape of the distorted electron beam spot on the conventional color cathode ray tube screen

4B is a view showing a shape in which an electron beam spot is distorted by a deflection magnetic field.

5 is a longitudinal sectional view showing a conventional astigmatism correction means;

6A and 6B are front views of the first focusing electrode shown in FIG.

7A and 7B are front and partial longitudinal cross-sectional views of the second focusing electrode shown in FIG.

8 is an explanatory diagram when a quadrupole lens is applied in order to improve the spreading in the periphery of a conventional screen;

9 is a beam spot diagram when a conventional quadrupole lens is used;

10 is a longitudinal sectional view showing the main part of the present invention;

FIG. 11 is a front view illustrating an electrode of the second and third focusing electrodes; FIG.

12A and 12B are cross-sectional views taken along the line A-A, B-B of FIG.

13 is a front view illustrating horizontal correction electrodes of the third and fourth focusing electrodes;

14A and 14B are cross-sectional views taken along lines C-C, D-D of FIG.

15 is a front view illustrating an embodiment of a plate electrode fixed to the first and second focusing electrodes.

16 is a front view showing another embodiment of a plate electrode fixed to the first and second focusing electrodes;

17 is an explanatory diagram when a quadrupole lens is applied to improve the spreading at the periphery of the present invention screen;

Fig. 18 is a beam spot diagram when the quadrupole lens of the present invention is used

Explanation of symbols for main parts of the drawings

27: first focusing electrode 28: second focusing electrode

29: third focusing electrode 30: fourth focusing electrode

33, 36: horizontal correction electrode 33a, 36a: horizontal blade

34, 37: electrode 34a, 37a: electron beam passing hole

35, 38: guide inner electrode 39, 42: plate electrode

Hereinafter, the present invention will be described in more detail with reference to FIGS. 10 to 18 as an embodiment.

FIG. 10 is a longitudinal sectional view showing the main part of the present invention, FIG. 11 is a front view showing the electrodes of the second and third focusing electrodes, and FIG. 13 is a front view showing the horizontal correction electrodes of the third and fourth focusing electrodes.

According to the present invention, a focusing electrode is divided into a first focusing electrode 27, a second focusing electrode 28, a third focusing electrode 29, and a fourth focusing electrode 30. Dynamic voltages varying depending on the amount of deflection are applied to the 27 and 29, and a constant focus voltage (static voltage) is always applied to the second and fourth focusing electrodes 28 and 30.

The fourth focusing electrode 30 includes an electrode 31 having three circular electron beam passing holes 31a formed therein, a plate-shaped electrode 32 welded to one surface of the electrode (opposing surface of the third focusing electrode), It consists of a horizontal correction electrode 33 of a substantially "c" shape fixed to the plate electrode.

The horizontal correction electrode 33 extends into the third focusing electrode 29 to form a quadrupole lens at a predetermined distance from the guide inner electrode 35 fixed to the third focusing electrode 29.

As shown in FIGS. 11 and 12, the third focusing electrode 29 has an electrode 34 having three longitudinal electron beam through holes 34a having a vertical direction larger than a horizontal direction in a direction of the fourth focusing electrode 30. And a guide inner electrode 35 fixed to the inside of the electrode to form a quadrupole lens between the horizontal correction electrodes 33 of the fourth focusing electrode 30, and one surface of the electrode (opposite of the second focusing electrode). And a horizontal “correction” electrode 36 having a substantially “c” shape to form a quadrupole lens at a predetermined distance from the guide inner electrode 38 fixed to the second focusing electrode 28.

Horizontal correction electrodes 33 and 36 of the third and fourth focusing electrodes 29 and 30 are shown in detail in FIGS. 13 and 14.

11 and 12, the electrode 37 has three longitudinal electron beam through holes 37a each having a vertical direction larger than the horizontal direction in the direction of the third focusing electrode 29, as shown in FIGS. ), A guide inner electrode 38 fixed inside the electrode to form a quadrupole lens between the horizontal correction electrodes 36 of the third focusing electrode 29, and one side of the electrode (the first focusing electrode). And plate-shaped electrodes 39 fixed to the opposite surfaces of the substrates.

The first focusing electrode 27 forming the main lens includes an electrode 40 having an opening 40a formed on an opposite surface of the anode 15 and a guide inner electrode fixed to the inside of the electrode to control an electric field of the main lens. 41 and a plate-like electrode 42 fixed to one side of the electrode (the opposing face of the second focusing electrode).

The plate electrodes 39 and 42 fixed to the opposing surfaces of the first and second focusing electrodes 27 and 28 have three circular electron beam through holes 39a and 42a as shown in FIG. Alternatively, three keyhole-shaped electron beam through holes 39b and 42b may be formed as shown in FIG. 16 shown in another embodiment.

Referring to the operation of the present invention configured as described above is as follows.

In order to reduce the horizontal size of the electron beam spot at the periphery of the screen and to increase the vertical size, as shown in FIG. 17, the divergence angle α _oh is increased in the horizontal direction at the triode, and the electron beam divergence angle in the vertical direction is increased. By decreasing α _OV ), the horizontal and vertical angles of incidence α _ix (α _iy ) incident on the screen are made approximately equal.

In addition, since the electron beam spot (H1 = V1) in the horizontal and vertical directions of the main lens is enhanced to be substantially circular, as shown in FIG. 18, the astigmatism of the main lens is enhanced to improve the conventional problem.

However, since the astigmatism is adjusted at the periphery of the screen at the center of the screen, focus deterioration occurs at the center of the screen.

Accordingly, in the present invention, the focus is improved over the entire area of the screen by complementing the quadrupole lens formed in the first, second, third, and fourth focusing electrodes 27, 28, 29, and 30.

The quadrupole lens Q1 formed between the third focusing electrode 29 and the fourth focusing electrode 30 has a horizontal divergence angle α _{1 of an} electron beam having a large horizontal divergence angle generated at the triode. It decreases and increases the divergence angle (α ₁ ') in the vertical direction, thereby making the spot shape in the center of the screen almost circular.

In addition, the quadrupole lens Q formed between the second focusing electrode 28 and the third focusing electrode 29 increases the divergence angle α _{2 in} the horizontal direction to correct astigmatism at the center of the screen. It serves to reduce the divergence angle (α ₂ ') in the vertical direction.

And the horizontal and vertical lens action depending on the shape of the electron beam passing holes 39a, 39b, 42a, 42b of the plate electrodes 39, 42 fixed to the first and second focusing electrodes 27, 28, respectively. As a result, the focusing voltage difference due to the distance difference between the screen peripheral part and the center part can be corrected.

At this time, the electron beam passing holes of the plate electrodes 39 and 42 fixed to the first and second focusing electrodes 27 and 28 are not circular holes 39a and 42a as shown in FIG. As shown in the figure, the keyhole shapes 39b and 42b have an advantage of maintaining the optimum focus across the entire screen even if the dynamic voltage is small.

The quadrupole lenses Q1 and Q formed between the second, third and fourth focusing electrodes 28, 29 and 30 are plate-shaped electrodes 32 of the third and fourth focusing electrodes 29 and 30. The horizontal blades 33a and 36a of the horizontal correction electrodes 33 and 36 fixed to the 43 are inserted into the elongated electron beam through holes 34a and 37a of the electrodes 34 and 37 to guide the inner electrode. Since it is kept at a constant distance from (35) and (38), the quadrupole lens 44 as shown in Fig. 6B is generated by different electric fields.

As described above, the present invention improves the spot shape of the periphery of the screen, thereby reducing the resolution and the moire phenomenon of the color cathode ray tube, thereby making it possible to manufacture a cathode ray tube of high quality.

Claims (5)

Electrostatic radiation means for emitting an electron beam, a triode consisting of a control electrode and an acceleration electrode for controlling the radiation amount and crossover of the electron beam, the shear focusing electrode for forming the electron beam and a main electrostatic lens for forming a electrostatic lens In an electron gun constituted by a focusing lens forming electrode, the focusing electrodes constituting the electrostatic focusing lens are divided into four electrodes to sequentially arrange the first, the second, the third, and the fourth focusing electrodes, and the fourth focusing electrode from the first focusing electrode. A constant voltage is applied to any one of the focusing electrodes forming each of the axially asymmetric quadrupole lenses and one of the axially asymmetric quadrupole lenses, and the remaining electrodes are applied to the electron beam deflection amount. A voltage that is synchronously applied is applied, and a horizontal correction electrode and a guide are provided to at least one of the respective focusing electrodes. An electron gun for a color cathode ray tube, comprising an inner electrode. The method of claim 1, The electron gun for color cathode ray tube, characterized in that the plate-shaped electrode is fixed to the electrode surface of the axisymmetric focusing lens forming electrode facing each other. The method of claim 2, An electron gun for a color cathode ray tube, wherein three electron beam through holes are formed in the axisymmetric focusing lens forming electrode. The method of claim 2, 3. An electron gun for a color cathode ray tube, wherein three electron beam through holes having a keyhole shape are formed in the axisymmetric focusing lens forming electrode. The method of claim 1, The horizontal correction electrode fixed to the focusing electrode forming the axially asymmetric quadrupole lens has a cross-section of the shape of "C" for three electron beam through-holes, so that the horizontal edge of each correction electrode has a longitudinal electron beam through-hole of the focusing electrode. Electron gun for color cathode ray tube, characterized in that installed through.