KR100777716B1 - Screen electrode of electron gun for CRT and electron gun therewith - Google Patents

Abstract

The present invention is to improve the resolution at the periphery of the screen by reducing the horizontal size of the electron beam incident to the main lens by complementing the focusing force of the electron beam emitted from the screen electrode in the horizontal direction, the longitudinal direction of the electron beam It relates to a screen electrode of a cathode ray tube electron gun and an electron gun having the same, characterized in that the elongated inlet portion and the transverse inlet portion have an electron beam through hole formed sequentially.

Description

Screen electrode of electron gun for cathode ray tube and electron gun with same

1 is a side view showing an electron gun for a conventional cathode ray tube.

2 is a perspective view showing the structure of a screen electrode of a conventional electron gun for a cathode ray tube;

3A and 3B are cross-sectional views showing the effects on the electron beam in the horizontal and vertical directions of the screen electrode according to FIG. 2, respectively.

4 is a schematic perspective view of an electron gun provided with a screen electrode according to the present invention;

5 is a cross-sectional view showing a horizontal and vertical section of the screen electrode according to the present invention.

6 is a perspective view showing another embodiment of a screen electrode according to the present invention.

7A and 7B are cross-sectional views illustrating the principle of operation of the screen electrode in the horizontal and vertical directions, respectively.

8A and 8B are diagrams showing distribution of equipotential lines in a horizontal direction and a vertical direction of a screen electrode according to the present invention, respectively.

9A and 9B are graphs showing electron beam current densities in the main lens when the screen electrodes of Comparative Example and Example of the present invention are used, respectively.

10A and 10B are cross-sectional views illustrating the principle of operation in a horizontal direction and a vertical direction of a screen electrode according to a comparative example and an embodiment of the present invention, respectively.                 

※ Explanation of symbols about main part of drawing ※

10: cathode 20: control electrode

30: screen electrode 40: focusing electrode

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to an electron gun for a color cathode ray tube having an improved resolution due to an improved structure of a screen electrode forming an asymmetric prefocus lens.

In general, a color cathode ray tube is fused with a funnel in which a neck portion is integrally formed on a panel, and an electron gun for firing three electron beams of red (R), green (G), and blue (B) is enclosed in the neck portion. The inner surface of the panel is coated with a fluorescent film which emits light as the electron beam collides. A deflection yoke is fixed across the funnel along the outer periphery of the neck to deflect the electron beam emitted from the electron gun.

FIG. 1 is a side view showing the configuration of an electron gun in such a color cathode ray tube, and includes three cathodes 1 for mounting a heater (not shown) to emit hot electrons in response to an input electric signal, and this cathode 1 The control electrode (2) for controlling the electron beam emitted in one direction of the screen, the screen electrode (3), which is an acceleration electrode for pulling and accelerating the electron beam gathered on the surface of the cathode (1), and a plurality of focusing electrodes for accelerating and narrowing the electron beam The fields 4 are arranged sequentially and in-line with respect to the three electrodes and are fixed by the bead glass 5.

As large-scale screens are increasingly required for color cathode ray tubes using such electron guns, wide angle deflection angles are required, and screen resolution is very important.

A typical cathode ray tube employs a self-converging deflection yoke having an pincushion type deflection field and a barrel type deflection field and an inline electron gun. During the deflection, the electron beam receives a quadrupole effect due to the distorted magnetic field in addition to the bipolar effect due to the deflection. This quadrupole effect causes astigmatism of the electron beam, and consequently, the image plane of the electron beam causes the vertical image plane to be positioned behind the screen, causing vertical haze at the periphery of the screen. Increasing the focus voltage in order to reduce the vertical overfocus is to cause under focusing in the horizontal direction to cause focus separation.

As such, a method of designing an asymmetric triode has been proposed in order to prevent the resolution from being degraded due to the focus separation phenomenon of the electron beam due to the self-convergence quadrupole effect.

Among them, as disclosed in U.S. Patent No. 4,629,933, the electron beam through hole of the control electrode has an elongated side on the incidence side and a transverse side on the exit side, so that the position of the cross-over points in the horizontal and vertical directions of the electron beam is Techniques are known that allow the to vary. However, the tripole portion of such a structure changes the position ratio of the crossover in the horizontal and vertical directions when the beam current increases, so that the focus separation phenomenon as described above cannot be compensated properly.                         

In addition, as disclosed in US Pat. No. 4,558,253, there is a technology in which an elongated electron beam through hole is formed in the control electrode, and an elongated electron beam through hole is formed in the screen electrode opposite to the control electrode. This cathode ray tube is deflected by reducing the angle of incidence to the main lens formed by the focusing electrodes positioned next by the elongated electron beam through hole formed in the control electrode and the horizontal electron beam through hole formed in the screen electrode. Uniformity of the vertical focus is achieved by minimizing the spread of the electron beam spot landing on the periphery of the screen by the vertical deflection field of the yoke.

However, these electron guns have limitations on the screen surface of the super large or the flat plane, and as described above, the vertical beam diameter of the electron beam in the center of the screen is rapidly increased as the current increases due to the change of the spot of the electron beam sensitively to the amount of change of current. Is lowered.

2 shows an electron gun currently in common use in connection with these problems. As shown, the electron beam passing holes 2a and 4a of the control electrode 2 and the focusing electrode 4 are formed in a circular shape, and the electron beam passing holes 3a of the screen electrode 3 pass through the circular electron beam toward the incident side. The ball was made to have a transverse inlet on the exit side. In the case of such an electron gun, as shown in FIGS. 3A and 3B, the focusing force of the pre-focus lens formed by the equipotential lines 6 between the screen electrode 3 and the focusing electrode 4 is horizontal. Reinforce in the vertical direction rather than the direction Thus, when the electron beam is magnetically deflected, the reduced vertical cross section of the electron beam reduces the vertical haze of the spot. However, this has a problem in that the incident angle of the horizontal beam to the main lens becomes large due to a slightly weak focusing force in the horizontal direction. Reference numeral "O", which is not described in the drawing, indicates a cross-over point.

The present invention has been made in order to solve the above problems, to form a two-stage inlet portion to the output side of the screen electrode to compensate the focusing force of the electron beam in the horizontal direction of the size of the horizontal direction of the electron beam incident on the main lens It is an object of the present invention to provide an electron gun for a color cathode ray tube which can reduce the resolution and improve the resolution at the periphery of the screen.

In order to achieve the above object, the electron gun for the color cathode ray tube according to the present invention is a cathode, a control electrode, and a screen electrode, which form a three-pole portion, in which an electron beam passing hole of a screen electrode is extended into an elongated inlet and an elongated inlet in the direction of the electron beam. Allow additions to be formed sequentially.

According to another feature of the present invention, in the screen electrode of the above-described configuration, the electron beam through hole can be made circular, and the elongate inlet and the elongate inlet are elongated electrode members and the elongate in the screen electrode. It can be made by attaching the electrode member in order.

According to still another feature of the present invention, the longitudinal length of the elongate inlet portion formed in the screen electrode can be equal to the longitudinal length of the laterally-formed inlet portion.                     

In addition, in order to achieve the above object, the present invention provides an electron gun for a color cathode ray tube comprising the screen electrode as described above.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

In the color cathode ray tube according to the present invention, the electron gun is installed in the neck portion of the cathode ray tube to emit an electron beam for exciting the fluorescent film, and the triode consisting of the cathode of the electron gun, the control electrode and the screen electrode and the auxiliary and main A plurality of focusing electrodes forming a lens is provided.

FIG. 4 shows a triode which forms an electron beam emission and a water point in the electron gun according to the preferred embodiment of the present invention.

As can be seen in the figure, the cathode 10, the control electrode 20, and the screen electrode 30 that form the tripolar portion are arranged in a row, and each of the electrodes 20, 30, 40 has three cathodes 10. The electron beam passing holes 20a, 30a, and 40a are formed in correspondence with each other.

A heater is built in the cathode 10 to heat the electron emission portion formed in front of the cathode 10 so that the electron beam is emitted. In addition, the control electrode 20 is provided adjacent to the cathode 10, and the electron beam through hole 20a is formed at a position corresponding to the cathode 10 as described above. The electron beam through hole 20a of the control electrode 20 may be formed in a circular shape as shown in the figure, and may be provided with an elongate or an elongated lead on the electron beam exit side. Any form possible is applicable. The control electrode 20 has a plate shape.                     

Next to the control electrode 20, a screen electrode 30 also formed in a plate shape is positioned, and the electron beam through hole 30a is coaxial with the electron beam through hole 20a of each of the cathode 10 and the control electrode 20. ) Is formed. An elongate first inlet portion 30b is formed at its edge along the electron beam exit side direction of the through hole 30a, and then a second inlet portion 30c is formed laterally. The first and second lead portions 30b and 30c formed on the screen electrode 30 will be described later.

In the focusing electrode 40 corresponding to the screen electrode 30, a circular electron beam passing hole 40a is formed coaxially with the electron beam passing hole 30a of the screen electrode 30. In this case, the shape of the electron beam through hole formed in the focusing electrode 40 is not limited to a circular shape, but may be modified in various forms for changing the cross section of the electron beam.

In addition, electron beam passing holes for forming an electron lens and a quadrupole lens are formed in the focusing electrodes other than the focusing electrode 40 installed adjacent to the screen electrode 30.

5 is a cross-sectional view for explaining in detail the structure of the electron beam through hole (30a) and the first and second inlet portion (30b, 30c) of the screen electrode 30 having the configuration as described above and Similarly, in the screen electrode 30 according to the preferred embodiment of the present invention, a circular electron beam through hole 30a is formed in a plate-shaped electrode member, and the exit side faces the edge of the electron beam through hole 30a. The long first inlet portion 30b of the long shape is press-pressed and the second long inlet portion 30c of the horizontal shape is press-pressed again. At this time, as in the vertical cross section of the figure, it is preferable that the longitudinal length of the longitudinally first inlet portion 30b is equal to the longitudinal length of the laterally second inlet portion 30c.                     

As shown in FIG. 6, the first and second lead-in portions 30b and 30c of the screen electrode 30 have an elongated through hole 32a in the screen electrode 33 in which the circular electron beam through hole 33a is formed. ) And plate-shaped electrode members 32 and 34 each having a transverse hole 34b formed thereon may be formed.

Next, the operation of the screen electrode according to the present invention configured as described above will be described with reference to the accompanying drawings.

As shown in FIG. 7A, the electron gun according to the present invention forms a first inlet in the electron beam through-hole 30a in the horizontal direction of the screen electrode 30, so that the distribution of the equipotential lines 50 is transferred to the electron beam through-hole 30a. Further penetration. This serves to further enhance the focusing force on the horizontal side of the electron beam passing through.

In addition, as shown in FIG. 7B, the longitudinal length of the first inlet part and the longitudinal length of the second inlet part are formed to be the same in the vertical direction to maintain the vertical focusing force of the electrode having the existing single transverse inlet part. It was.

This structure maintains the focusing force in the vertical direction and improves the focusing force in the horizontal direction, thereby reducing the horizontal angle of incidence of the electron beam incident on the main lens.

This can be clearly seen from the distribution of equipotential lines in the horizontal and vertical directions as shown in FIGS. 8A and 8B. Shown in the figure is the distribution of the equipotential lines in the screen electrode according to an embodiment of the present invention.

As can be seen in the figure, the potential distribution in the horizontal direction penetrates further toward the center electron beam through hole, thereby strengthening the horizontal focusing. In addition, the distribution of the vertical equipotential lines shown in FIG. 8B is also sufficient to maintain the existing vertical side focusing.

As described above, according to the screen electrode according to the preferred embodiment of the present invention, the electron beam size can be downsized, as shown in Table 1 below.

Here, the comparative example refers to a case where a screen electrode having a transverse inlet portion is used on the emission side as shown in FIG. 2.

Comparative example Example Diameter of horizontal beam 2.313 2.089 Diameter of vertical beam 2.516 2.497

In other words, the size of both the vertical and horizontal beams is smaller than the conventional single horizontal electrode, and it can be seen that the size of the horizontal beam is much better.

This can also be seen by looking at the distribution of the current density in the horizontal direction when incident on the main lens of the electron beam in the case of using the comparative example and the embodiment of the present invention, as shown in FIGS. 9A and 9B. In other words, in FIGS. 9A and 9B, the current density distribution at the time of incidence into the main lens is more angular than the flat top in the form having the tip of the comparative example, and the repulsive effect of the space charge is reduced in FIGS. 10A and 10B. Accordingly, the size of the horizontal electron beam can be reduced. 10A shows the space charge repulsion effect when the comparative example is used, and FIG. 10B shows the space charge repulsion effect when the present example is used.                     

After the electron beam of this shape passes through the main lens, the vertical electron beam components are underfocused so that the electron beam spot is vertically ellipsoidal at the center of the screen without the influence of the deflection magnetic field of the deflection yoke. Since it comes out in the form, even when the deflection yoke is deflected to the periphery of the screen, the effect of distorting the electron beam in the vertical direction can be canceled to prevent the resolution degradation at the periphery of the screen.

As described above, the electron gun for the color cathode ray tube according to the present invention forms a two-stage inlet at the emission side of the screen electrode constituting the tripolar portion to further reduce the beam size of the horizontal component of the electron beam, and to further reduce the size of the electron beam spot as a whole. Therefore, the degradation of the resolution at the periphery of the screen can be prevented.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (8)

It has an electron beam through hole formed in the elongated inlet portion and the transverse inlet portion sequentially formed in the emission side direction of the electron beam, And a longitudinal length of the elongate inlet is equal to a longitudinal length of the elongate inlet. The method of claim 1, The electron beam passing hole is a screen electrode of the electron gun for cathode ray tube, characterized in that the circular. The method of claim 1, The elongated inlet and the elongated inlet may be formed by sequentially attaching an electrode member having an elongated through hole to one side of the screen electrode and an electrode member having an elongated through hole sequentially. delete Three cathodes for emitting an electron beam; A control electrode positioned to one side of the cathode to control the emitted electron beam; A screen electrode installed adjacent to the control electrode and having an electron beam through hole sequentially formed in the elongated inlet and the inlet of the transverse in the emission direction of the electron beam; A plurality of focusing electrodes provided adjacent to the screen electrode to form a plurality of quadrupole lenses; And The final acceleration electrode is installed adjacent to the focusing electrode, And the longitudinal length of the elongate inlet is equal to the longitudinal length of the elongate inlet. The method of claim 5, The electron beam through-holes are electron guns for color cathode ray tube, characterized in that the circular. The method of claim 5, The elongated lead and the elongated lead are formed by sequentially attaching an electrode member having an elongated through hole to one side of a screen electrode and an electrode member having an elongated through hole sequentially formed. delete

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