JPH0582048A - In-line type electron gun - Google Patents

Abstract

PURPOSE:To provide an in-line type electron gun, which permits reducing distortion of the electron beam spot dia. due to deflective astigmatism, obtaining the optimum focusing not only in the central zone of a screen but also at the peripheral zones, and acquiring high resolutions over the whole screen areas. CONSTITUTION:Electron beam passing apertures 2c, 2d in a first grid 2 are formed so that the objective point in horizontal direction of the three-pole part viewed from a main lens part lies farther than the objective point in the vertical direction and also so that, the emittance in vertical direction in this three-pole part is smaller than that in the horizontal direction. At the same time, the shapes and sizes of a visor-cum-electrode 4d and electron beam passing apertures 4b, 4c in an electrode 4 constituting the main lens are made so that the focusing voltage in the horizontal direction of the main lens part is 150-300 V higher than the focusing voltage in the vertical direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line type electron gun which emits three electron beams in one horizontal plane.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional cathode ray tube equipped with an in-line type electron gun for emitting three electron beams on one horizontal plane.
FIG. 1 is a diagram showing a schematic configuration of a pole part and its electron beam trajectory.
Is a cathode, 2 is a first grid, 3 is a second grid,
The cathode 1 is circular, the electron beam passage hole of the first grid 2 is circular, the electron beam passage hole of the second grid 3 is circular 3a on the first grid side, and the horizontally elongated slot 3b is on the main lens side.
Is formed in. Reference numeral 5v indicates the outermost electron beam trajectory in the vertical direction, and 5h indicates the outermost electron beam trajectory in the horizontal direction.

Generally, a conventional electron beam deflection system in a cathode ray tube equipped with an in-line type electron gun makes a dynamic convergence circuit unnecessary by automatically focusing three electron beams on a screen. Therefore, the horizontal deflection magnetic field is pincushion-shaped, and
It uses a self-convergence system that distorts the vertical deflection magnetic field in a barrel-like manner. This system has many advantages such as easy adjustment, low cost, and little change in convergence over time, and is widely used at present.

However, the quadrupole magnetic field component generated by the nonuniform magnetic field produced by the self-convergence deflection yoke causes astigmatism in the deflected electron beam. Therefore, the electron beam undergoes a focusing action, that is, a deflection aberration in the vertical direction, and as a result, the deflected electron beam spot becomes overfocused in the vertical direction, causing a particularly long halo around the screen and deteriorating the vertical resolution. On the other hand,
Since the optimum focus is always maintained in the horizontal direction, the optimum correction in the vertical direction causes underfocus in the horizontal direction this time, resulting in a problem that the horizontal resolution deteriorates.

Therefore, in order to solve this problem, in the conventional in-line type electron gun, the prefocus lens action is strengthened to narrow down the electron beam, and the electron beam diameter in the deflection magnetic field is kept small to be influenced by the deflection aberration. In order to reduce the deflection distortion in the vertical direction, the electron beam diameter in the main lens is often set to be laterally long, in practice, in order to reduce the deflection distortion in the vertical direction. 2 grid 3
There is used a method of giving a quadrupole lens action to the third grid by forming the electron beam passage hole of the above-mentioned shape into a horizontally long slot 3b.

[0006]

However, in the method of narrowing the electron beam by strengthening the action of the prefocus lens, the magnification of the prefocus lens is increased, the virtual object point is enlarged, and the electron beam spot diameter is increased. Therefore, even if the deflection distortion around the screen can be reduced, the electron beam spot diameter at the center of the screen increases as shown in FIG. 9 and the resolution of the entire screen deteriorates.

Further, only by making the electron beam diameter at the deflection center laterally long, as shown in FIG. 9, the optimum focus cannot be obtained at the center of the screen, and it is difficult to obtain a circular electron beam spot. You cannot improve the resolution on the entire screen. For this reason, a method of adopting a compromise between the focus on the periphery of the screen and the focus on the center of the screen and making the resolution of the entire screen uniform within a possible range has been adopted.

In the method of making the electron beam passage hole 3b of the second grid 3 into a horizontally long slot as shown in FIG. 7, which is adopted as a concrete method, electrons emitted from the cathode 1 as shown in FIG. Since the shape of the beam is circular, there is a limit to making the electron beam horizontally long only by the action of a quadrupole lens such as a prefocus lens after that, and even if the electron beam passage hole of the first grid 2 is horizontally long, That alone does not solve the above problems.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the distortion due to the deflection aberration and to realize the optimum focus not only at the center of the screen but also at the periphery of the screen, which is high over the entire screen. The purpose is to obtain an in-line type electron gun capable of obtaining resolution.

[0010]

According to the in-line type electron gun of the present invention, the horizontal object point of the three-pole portion viewed from the main lens portion is located farther than the vertical object point. , So that the vertical emittance at these three poles is smaller than the horizontal emittance.
And the shape of the electron beam passage hole of the second grid is formed, and the difference between the horizontal focus voltage and the vertical focus voltage of the main lens portion (hereinafter, “(horizontal focus voltage) − (vertical focus voltage)” is "Astigma") is negative.

In the above structure, since the horizontal object point position viewed from the main lens portion is formed farther than the vertical object point position, the quadrupole lens formed on the second grid side of the first grid. First, to strengthen the action in the horizontal direction
The electron beam passage hole on the second grid side of the grid is formed vertically long, and in order to reduce the emittance in the vertical direction, the shape of the electron beam passage hole on the cathode side of the first grid is formed horizontally long.

Further, in order to make the stigma of the main lens portion negative, the electron beam passage hole at the center of the electrode forming the main lens portion is formed into a vertically elongated elliptical shape, and the electron beam passage holes on both sides are formed into odd elliptical shapes. Two main lens forming electrodes having eave electrodes surrounding the three electron beam passage holes are formed to face each other.

[0013]

[Action] line electron gun according to the present invention, the diameter DSM of the electron beam at the deflection center (D iameter
S ize in M ain lens vertical direction DS of)
Mv is hardly deflection aberration receives becomes smaller, the diameter DS of the electron beam spot on the screen (D iamet
er S ize) the center of the screen resolution is higher because the vertical DSv becomes small, good resolution is obtained in the entire screen.

[0014]

【Example】

Example 1. FIG. 1 is a diagram showing a schematic structure of a three-pole portion and a main lens portion and an electron beam trajectory thereof according to an embodiment of the present invention.
Is a diagram using a beam cross section, FIG. 3 is a diagram showing the electron beam diameter in the main lens and the electron beam spot diameter on the screen, FIG. 4 is a diagram showing the configuration of the first grid, and FIG. 5 is a first diagram. FIG. 6 is a diagram showing the action of the grid, and FIG. 6 is a diagram showing electrodes forming the main lens.

In FIGS. 1 and 2, the three-pole part is constructed so that the position of the horizontal object point as viewed from the main lens portion is farther than the position of the vertical object point. Therefore, the electron beam passage hole of the first grid 2 strengthens the vertical action of the cathode-side quadrupole lens among the quadrupole lenses formed on the cathode side and the second grid side, respectively. Strengthens the horizontal action of the quadrupole lens on the side.

Of these, the action of the quadrupole lens on the cathode side greatly contributes to the quality of the electron beam, and the action of the quadrupole lens on the second grid side greatly contributes to the focusing of the electron beam, that is, the formation of the object point. It is conceivable that the position of the object point in the horizontal direction seen from the main lens part can be formed farther than the position of the object point in the vertical direction, and the emittance amount at both object point positions can be made larger than that in the vertical direction. The emittance in the horizontal direction can be made smaller, and as shown in FIG. 5, a laterally long astigmatic electron beam can be formed in the main lens portion, and the deflection aberration in the vertical direction can be reduced. You can

FIG. 4 is a diagram showing an example of the structure of the first grid 2 forming the quadrupole lens as described above. The first grid 2 is formed by stacking two electrode plates 2a and 2b on each other and forming a first electrode plate. A vertically long slot 2c is formed in 2a, a horizontally long square hole 2d is formed in the second electrode plate 2b, and the first electrode plate 2a is formed.
Are arranged on the second grid side.

Further, in this embodiment, the stigma in the horizontal and vertical directions of the main lens portion is -150 to -300.
The focus characteristic of the main lens unit is set so as to be within the range of V so that the focal length of the electron beam is shorter in the horizontal focal length so that optimum focus can be obtained over the entire screen.

FIG. 6 is a diagram showing an example of the structure of the main lens forming electrode 4 forming the main lens portion that can obtain the above-mentioned focus characteristics. Reference numeral 4a denotes a plate in which three electron beam passage holes are formed, and 4b. Is the center electron beam passage hole, 4c
Is an electron beam passage hole on both sides, 4d is an eave electrode having a height Hv forming an oval opening, and the center electron beam passage hole 4b is a vertically elongated elliptical shape with a long axis Cv and a short axis Ch. The center of the electron beam passage hole 4c has a long axis Cv,
An elliptic arc having a short axis Ch and a deformed elliptical shape having an arc having a radius Sr on the outer side are formed, and the illustrated electrodes 4 are arranged so as to face each other at a predetermined interval to form a main lens electrode.

The focusing characteristics of the main lens forming electrode can be made to have desired characteristics by changing the shape and size of the electron beam passage holes 4b and 4c, and the shape and the depth of the eaves electrode 4d. it can.

By combining the three-pole part and the main lens part having the above-described structure, the orbit of the electron beam becomes as shown in FIG. 1, and the shape of the electron beam at the deflection center becomes a horizontally long ellipse, so that the vertical direction is obtained. Is less subject to the deflection aberration of, and the optimum focus can be obtained at the center of the screen.
Further, since the stigma of the main lens unit is made negative, the optimum focus can be obtained even in the periphery of the screen, so that the optimum focus can be realized over the entire screen.

Example 2. In the first embodiment described above, the electron gun of the other-stage focusing type has been described, but the same effect can be obtained by applying the electron gun of the bipotential type.

[0023]

As described above, according to the present invention, the deflection distortion of the self-convergence system of the in-line type electron gun is such that the electron beam shape at the deflection center is laterally long and the vertical focal length thereof is horizontal. Since the focal length is shorter than the focal length, not only the vertical focusing effect of the pincushion magnetic field is reduced to prevent deflection aberrations, but also optimal focus can be achieved over the entire screen and high resolution can be achieved. It has the effect of getting a gun.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of Example 1 of the present invention and an electron beam trajectory thereof.

FIG. 2 is a diagram showing a basic configuration of the first embodiment using a beam cross section.

FIG. 3 is a diagram showing beam trajectories in the basic configuration of the first embodiment.

FIG. 4 is a diagram illustrating a configuration example of a first grid according to the first embodiment.

5 is a diagram showing a beam trajectory by the first grid in FIG. 4;

FIG. 6 is a diagram showing a configuration example of a main lens forming electrode of Example 1.

FIG. 7 is a diagram showing a schematic configuration of a conventional in-line type electron gun and its electron beam trajectory.

FIG. 8 is a diagram showing a basic configuration of a conventional electron gun using a beam cross section.

FIG. 9 is a diagram showing a beam trajectory in a conventional example.

[Explanation of symbols]

 1 cathode 2 first grid 2c electron beam passage hole on second grid side 2d electron beam passage hole on cathode side 3 second grid 3a round hole 4 main lens forming electrode 4a plate 4b center electron beam passage hole 4c electrons on both sides Beam passage hole 4d Eave electrode 5h Vertical outermost electron beam trajectory 5v Horizontal outermost electron beam trajectory

Claims (5)

[Claims] 1. A three-pole portion composed of three cathodes arranged inline in the horizontal direction, a first grid and a second grid each having three electron beam passage holes, and three electrons formed in the three-pole portion. In an in-line type electron gun having a main lens section for focusing each beam, the horizontal object point of the three-pole section viewed from the main lens section is located farther than the vertical object point, and The electron beam passage holes of the first and second grids are formed so that the vertical emittance at the three-pole portion is smaller than the horizontal emittance, and the horizontal focus voltage of the main lens portion is vertical. The electron beam passage hole and the entire shape of the electrode forming the main lens are configured so as to be lower than the focus voltage in the direction. An in-line type electron gun. 2. The quadrupole lens formed in the opening on the second grid side in which the action of the quadrupole lens formed on the cathode side of the electron beam passage hole of the first grid is strong in the vertical direction. The in-line type electron gun in which the shape of the electron beam passage hole of the first grid is formed so that the action of (1) becomes stronger in the horizontal direction. 3. The electron beam passage hole of the first grid according to claim 2, wherein the cathode side has a horizontally long square hole, and the second grid side has a vertically long square hole. In-line type electron gun formed in a slot that is sufficiently larger than the height of 4. The difference between the horizontal focus voltage and the vertical focus voltage of the main lens portion is −
In-line type electron gun characterized by being set to 150 V to -300 V 5. The electrode forming the main lens according to claim 1, wherein the center electron beam passage hole is formed into a vertically elongated elliptical shape, and the electron beam passage holes on both sides are formed into an elliptical arc with the center side being an elliptic arc and the side sides being an arc. And an in-line type electron gun having two main lens forming electrodes opposed to each other and having eaves electrodes surrounding the three electron beam passage holes.