KR100823473B1 - Electron gun for beam index type cathode ray tube - Google Patents

Abstract

In the electron beam scanning process, the vertical beam diameter of the screen is minimized by minimizing the change in the vertical beam diameter of each part of the screen, and an electron gun of the beam index type cathode ray tube which maintains uniform color purity characteristics over the entire screen is provided.

The electron gun includes a cathode for emitting hot electrons, first and second grid electrodes for controlling the emission of the hot electrons, and a plurality of individual electrodes electrically separated from each other, and a variable focus voltage is supplied to at least one of the hot electrons. A plurality of third grid electrodes for focusing with an electron beam, a fourth grid electrode for supplying an anode voltage to accelerate the electron beam to a fluorescent screen, and a support for integrally aligning the cathode and the plurality of grid electrodes; The cathode and the first and second grid electrodes constitute a triode tube portion, and a fixed voltage is supplied to any one of the third grid electrodes facing the triode tube portion together with a plurality of electrodes constituting the triode tube portion to keep the electric field of the triode portion constant. .

Cathode ray tube, beam index, electron gun, triode portion, grid electrode, anode electrode, fluorescent film, electron beam, cathode

Description

Electron gun of beam index type cathode ray tube {ELECTRON GUN FOR BEAM INDEX TYPE CATHODE RAY TUBE}

1 is a cross-sectional view of an electron gun for a beam index type cathode ray tube according to the present invention.

FIG. 2 is a cross-sectional view of the beam index type cathode ray tube mounted with the electron gun shown in FIG. 1. FIG.

Figure 3 is an enlarged view of the triode portion in the electron gun according to the present invention.

4 is a schematic diagram for explaining the conditions for measuring the vertical beam diameter of an electron beam.

Figure 5 is a graph showing the results of measuring the change in the vertical beam diameter according to the horizontal deflection of the electron beam in each of the electron gun according to the present invention and the prior art.

Figure 6 is a graph showing the results of measuring the vertical beam diameter change according to the vertical direction deflection of the electron beam in each of the electron gun according to the present invention and the prior art.

Fig. 7 is a schematic diagram for explaining the relationship between the electron beam diameter and the fluorescent film screen.

8 is an enlarged view of a triode portion in an electron gun according to the prior art;

Fig. 9 is a schematic diagram for explaining the change in the vertical beam diameter of the electron beam reaching the fluorescent film screen and the resulting screen defect when the electron gun is mounted according to the prior art.

The present invention relates to a beam index type cathode ray tube, and more particularly, a beam capable of improving the vertical resolution of a screen by minimizing the change in the vertical beam diameter of the electron beam for each part of the screen, and maintaining a uniform color purity characteristic throughout the screen. An electron gun of an index type cathode ray tube.

In general, a beam index type cathode ray tube is a cathode ray tube that color-selects an electron beam by using an index stripe and a light sensor instead of a shadow mask, and a single-line electron beam emits one point as in a general cathode ray tube by applying a single electron gun that emits a single electron beam. There is no mis-convergence that is not concentrated in the system, and since the shadow mask is not attached, it does not suffer from the doming and moire phenomena.

However, in the beam index type cathode ray tube, since the shadow mask is omitted, as shown in FIG. 7, the electron beam reaching the fluorescent screen 1 is obtained by adding one fluorescent film stripe 3 and two black matrix films 5. Since the width should be smaller than that to avoid other color invasion, the electron beam should have a fine beam diameter.

However, the electron beam has a tendency to increase horizontal and vertical beam diameters as it moves away from the center of the screen due to the geometric structure of the face panel constituting the beam index type cathode ray tube and the spherical aberration of the electron gun and the deflection aberration of the deflection yoke. Until now, the electron gun applied to the beam index type cathode ray tube has a problem in that the electric field of the triode which determines the cross over of the electron beam is varied by the focus voltage, and thus the vertical beam diameter is changed for each position of the screen.                         

That is, the electron beam diameter formed on the fluorescent film screen is proportional to the diameter of the electron beam in the prefocus lens, that is, the size of the crossover image. In the conventional art, the electron gun has a cathode and a fixed voltage is applied to the G1 electrode and G2 electrode constituting the triode. On the other hand, the variable focus voltage set to implement the optimum focus is applied to the G3-1 electrode facing the G2 electrode according to the landing position of the electron beam.

Therefore, the variable focus voltage applied to the G3-1 electrode affects the triode tube electric field through the hole of the G2 electrode, thereby changing the size of the crossover phase.

FIG. 8 is a view illustrating a focusing pattern of an equipotential line and an electron beam formed in a triode tube part of an electron gun according to the prior art, wherein fixed voltages of −100 V and +1,000 V are applied to the G1 electrode and the G2 electrode, respectively, and the G3-1 electrode. The case in which the variable focus voltage is applied to is illustrated.

In this case, the electron beam shows a position of the vertical crossover where the vertical beam diameter is minimized due to the variable focus voltage and a result of non-uniform size, and shows a large difference in the degree of divergence toward the fluorescent screen 1. There is a large difference in the vertical beam diameter of the electron beam landing on the membrane screen 1.

Moreover, the irregular characteristic of the vertical crossover is further caused by the mutual influence of the focus voltage and the deflection magnetic field in the electron beam scanning process.

FIG. 9 illustrates a change in the vertical beam diameter of an electron beam that reaches a fluorescent screen when the conventional electron gun is applied to a beam index type cathode ray tube, and the electron beam is horizontally moved by a pincushion type magnetic field as it is deflected to the periphery of the screen. In the process of moving to the horizontal beam diameter increases, wherein the focus voltage acts in the direction of reducing the horizontal beam diameter to maintain color purity, and consequently increases the vertical beam diameter of the electron beam.

As a result, the vertical beam diameter of the electron beam gradually decreases as it is deflected to the periphery of the screen, and then rapidly increases at the periphery of the screen. As a result, the cathode ray tube screen along the point (shown by the dotted line) where the vertical beam diameter of the electron beam is minimum is shown. A screen defect with a circular reddish magenta is indicated.

This phenomenon is because the color saturation of the R phosphor among the three phosphors of R, G, and B is higher than the color saturation of the G and B phosphors. Therefore, when the vertical beam diameter decreases and the current density of the electron beam becomes high, the luminance of the R phosphors becomes G and B. This is due to the higher luminance of the phosphor.

As a result, in the triode structure affected by the variable focus voltage, the vertical beam diameter of the electron beam is changed for each position of the screen on which the electron beam is scanned due to the electric field change and the mutual influence of the focus voltage and the deflection magnetic field. And the problem of greatly reducing the color purity characteristics.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to equalize the position and size of the vertical crossover of the electron beam in the triode, thereby minimizing the change in the vertical beam diameter of the electron beam reaching the fluorescent screen. An electron gun of a beam index type cathode ray tube capable of improving vertical resolution is provided.                         

Another object of the present invention is to improve the color purity characteristics of the entire screen by suppressing the screen defects due to the reduction of the vertical beam diameter of the electron beam, and to provide an electron gun of the beam index type cathode ray tube that can maintain a uniform image quality characteristics in both the center and periphery of the screen To provide.

In order to achieve the above object, the present invention,

And a cathode for emitting hot electrons, first and second grid electrodes for controlling the emission of the hot electrons, and a plurality of individual electrodes electrically separated from each other, and a variable focus voltage is supplied to at least one of the hot electrons as an electron beam. A plurality of third grid electrodes for focusing, a fourth grid electrode supplied with an anode voltage to accelerate the electron beam to a fluorescent screen, and a support for integrally aligning the cathode and the plurality of grid electrodes,

The cathode and the first and second grid electrodes constitute a triode portion, and a fixed voltage is supplied to any one of the third grid electrodes facing the triode portion along with a plurality of electrodes constituting the triode portion to maintain an electric field of the triode portion constantly. An electron gun of a beam index type cathode ray tube is provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a sectional view of an electron gun for a beam index type cathode ray tube according to the present embodiment, and FIG. 2 is a sectional view of a beam index type cathode ray tube mounted with the electron gun.                     

As shown, the beam index type cathode ray tube is equipped with a single electron gun 4 which emits a single electron beam 2, and a plurality of index stripes 8 on the surface of the fluorescent film screen 6 facing the electron gun 4. And a light collecting plate 12 and an optical sensor 14 for detecting the index light to the outside of the light receiving window 10a of the funnel 10.

With the above configuration, when the electron beam 2 emitted from the electron gun 4 excites the index stripe 8 to emit the index light 16 in the ultraviolet region, the light collecting plate 12 and the light sensor 14 emit the index light. Detects (16) and converts it to an index signal.

The index circuit 18 controls the current density and the degree of deflection by synchronizing the provided index signal with the color signal, and provides a control signal to the electron gun 4 and the deflection yoke 20 to implement a desired color.

Here, the electron gun 4 provided in the present embodiment is to improve the vertical resolution of the screen by minimizing the change in the vertical beam diameter of the electron beam during the electron beam scanning process. As shown in FIG. 1, the electron gun 4 emits hot electrons. It consists of a single cathode K and a plurality of grid electrodes arranged at regular intervals from the cathode K by a pair of bead glass 22 as a support.

More specifically, the grid electrodes are separated into a cylindrical first grid electrode G1 surrounding the cathode K, a plate-shaped second grid electrode G2, and three separate electrodes and from their respective voltage sources. A plurality of third grid electrodes G3-1, G3-2, and G3-3 for supplying the corresponding voltages and a fourth grid electrode G4 for supplying the anode voltage are provided. (Hereinafter, the first to fourth grid electrodes are referred to as 'G1, G2, G3-1, G3-2, G3-3, and G4 electrodes', respectively.)

The G1 electrode and the G2 electrode together with the cathode K constitute a triode part, and a fixed voltage is supplied to both the cathode K and the G1 and G2 electrodes, and a prefocus lens (not shown) is applied due to the voltage difference applied to the electrodes. To form.

In the G3 electrode and the G4 electrode forming the main focus lens (not shown), a fixed medium voltage Vc is applied to the G3-1 electrode facing the G2 electrode, and the heavy field is respectively applied to the G3-2 electrode and the G3-3 electrode. A voltage and a variable medium voltage (variable focus voltage Vf) are applied, and a high voltage is applied to the G4 electrode to take a modified Uni-Bi potent focus method.

Therefore, in the present embodiment, a fixed voltage is applied to both the G1 and G2 electrodes constituting the triode tube portion together with the cathode, and the G3-1 electrode facing the G2 electrode, thereby maintaining a constant electric field of the triode portion forming the prefocus lens. Minimize the effect of the variable focus voltage supplied to the -3 electrode on the triode field.

FIG. 3 is a view illustrating a focusing pattern of an equipotential line and an electron beam formed in a triode tube part of an electron gun according to the present embodiment, wherein a fixed voltage of -100 V and +1,000 V is applied to the G1 electrode and the G2 electrode, respectively, and G3 The case where a fixed voltage of +8,000 V is applied to the −1 electrode is shown.

In the case described above, the electrons emitted from the cathode K have a substantially constant flow of electrons constituting the vertical beam diameter due to the uniform electric field characteristic of the triode, and there is no significant difference in the degree of divergence toward the screen. There is no significant difference in the vertical beam diameter of the electron beam reaching the membrane screen.                     

At this time, the electron gun 4 is a tripolar tube portion is designed for astigmatism, the astigmatism design is characterized in that the vertical beam diameter of the electron beam does not gather at a particular point.

In addition, in the above structure, since the electric field of the triode is kept constant, the electron beam traveling inside the electron gun 4 is uniformly emitted toward the screen without being greatly affected by the focus voltage Vf applied to the G3-3 electrode. It shows a tendency.

The diverging pattern of the electron beam cancels the force that the electron beam is contracted in the vertical direction by the pincushion type magnetic field of the deflection yoke 20, thereby suppressing the rapid reduction and expansion of the vertical beam diameter, and the vertical beam diameter of the vertical beam diameter in the electron beam scanning process throughout the screen. Minimize size changes.

As a more specific embodiment, in the 29-inch beam index type cathode ray tube having a 110 ° deflection angle, the electron gun according to the prior art (hereinafter referred to as "comparative example") and the electron gun according to the present embodiment are shown in FIG. As shown, the change in the vertical beam diameter that occurs in the process of the electron beam is deflected in the horizontal direction from the center of the screen (C) toward the horizontal end (D1) (see arrow A), and the electron beam is the vertical end (D2) in the center of the screen (C). 5 and 6 show changes in the vertical beam diameter which appear in the process of deflecting in the vertical direction toward (see arrow B).

Here, the measurement results described above are measured when the following voltage is applied to each electrode constituting the electron gun, as shown in Table 1, and the configuration of the electron gun 4 of the present embodiment is shown in FIG. The electron gun of the comparative example has the same dimensional characteristics as the electron gun 4 of this embodiment except that the G3-1 electrode and the G3-3 electrode are electrically connected in the configuration of FIG. 1 to supply the same variable focus voltage Vf. Indicates the case of

G1 electrode voltage (V) G2 electrode voltage (V) G3-1 electrode voltage (V) G3-2 electrode voltage (V) G3-3 Electrode Voltage (V) G4 electrode voltage (V) Comparative example -100 1,000 7,000-9,000 0 to 1,000 7,000-9,000 32,000 Example -100 1,000 5,000-7,000 0 to 1,000 7,000-9,000 32,000

Referring to the change in the vertical beam diameter of the electron beam measured under the above driving conditions, first, as shown in FIG. 5, in the comparative example in which the variable focus voltage Vf is applied to the G3-1 electrode (see dotted line), the electron beam is positioned at the center of the screen. The vertical beam diameter gradually decreases as it is deflected toward the horizontal end, and then the vertical beam diameter increases rapidly as it exceeds approximately 100 mm from the center of the screen.

On the other hand, in an embodiment in which a fixed voltage Vc is applied to the G3-1 electrode (see the solid line), as the electron beam is deflected from the center of the screen toward the horizontal end, the vertical beam diameter gradually decreases, and exceeds approximately 130 mm from the center of the screen. As a result, the vertical beam diameter gradually increases.

Table 2 below shows the minimum and maximum values of the vertical beam diameter and the amount of change in the vertical beam diameter according to the measurement results of the comparative example and the embodiment shown in FIG. 5.

Minimum value of vertical beam diameter (mm) Value of vertical beam diameter (mm) Vertical beam diameter change amount (mm) Comparative example 0.06 0.65 0.59 Example 0.10 0.21 0.11

As can be seen from the table above, the electron gun 4 according to the present embodiment effectively reduces the amount of change in the vertical beam diameter in comparison with the electron gun of the comparative example, and furthermore, effectively suppresses the increase in the vertical beam diameter occurring at the horizontal end of the screen, thereby reducing the verticality of the comparative example. Compared with the beam diameter, the vertical beam diameter reduced by about 1/3 is realized.

On the other hand, looking at the change in the vertical beam diameter of the electron beam shown in Figure 6, in the comparative example shown by the dotted line, as the electron beam is deflected from the center of the screen toward the vertical end, the vertical beam diameter decreases gradually, and as the distance from the screen center is about 100 mm away. This results in a sharp increase in the vertical beam diameter.

On the other hand, in the present embodiment shown by the solid line, the vertical beam diameter gradually decreases as the electron beam is deflected from the center of the screen to the vertical end as in the comparative example, but as the distance from the center of the screen is approximately 100 mm, the vertical beam diameter is gentle. Results increase.

Table 3 below shows the minimum and maximum values of the vertical beam diameter and the amount of change in the vertical beam diameter according to the measurement results of the comparative example and the embodiment shown in FIG. 6.

Minimum value of vertical beam diameter (mm) Value of vertical beam diameter (mm) Vertical beam diameter change amount (mm) Comparative example 0.08 1.23 1.15 Example 0.11 0.40 0.29

As can be seen from the table above, even in the case where the electron beam is deflected in the vertical direction, the electron gun 4 according to the present embodiment effectively reduces the amount of change in the vertical beam diameter compared with the electron gun of the comparative example, and furthermore, at the vertical end of the screen, Compared with the vertical beam diameter, the vertical beam diameter is reduced to about 1/4.                     

As such, the embodiment has the advantage of minimizing the change of the vertical beam diameter of the electron beam to improve the vertical resolution of the screen and maintaining a uniform color purity characteristic throughout the screen by maintaining the electric field of the triode constant.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, the present invention maintains a constant position and size of the vertical crossover formed in the triode, thereby suppressing the change of the vertical beam diameter of the electron beam due to the focus voltage, and vertically at the periphery of the screen due to the interaction of the deflection magnetic field and the focus voltage. The increase in beam diameter is effectively suppressed to maintain a uniform vertical beam diameter throughout the screen. Therefore, the present invention improves the vertical resolution and color purity characteristics of the screen, and has an effect of preventing a screen defect due to the rapid reduction and enlargement of the vertical beam diameter.

Claims (3)

A cathode for emitting hot electrons; First and second grid electrodes, together with the cathode, configured to form a triode and control the emission of the hot electrons; A third grid electrode comprising at least two electrodes that are electrically separated, and configured to focus the hot electrons into an electron beam; A fourth grid electrode supplied with an anode voltage to accelerate the electron beam to a fluorescent screen; And A support for integrally aligning the cathode and the first to fourth grid electrodes, A variable focus voltage is supplied to one electrode of the third grid electrode, and a fixed voltage is supplied to the other electrode of the third grid electrode facing the second grid electrode to maintain a constant electric field of the triode portion. Electron gun of type cathode ray tube. The method of claim 1, The third grid electrode is composed of a G3-1 electrode, a G3-2 electrode and a G3-3 electrode sequentially arranged from the second grid electrode toward the fourth grid electrode, the fixed voltage is applied to the G3-1 electrode Electron gun of beam index type cathode ray tube supplied. The method of claim 2, An electron gun of a beam index type cathode ray tube to which a variable focus voltage is applied to the G3-3 electrode.

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