JP2000260346A - Electron gun for color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve focus during heavy-current and downsize an electron beam spot from light-current to heavy-current, by providing an opening-type corrective electrode in a low-voltage-side first focusing electrode in focusing electrodes and in a main lens electric field region. SOLUTION: Openings 7a-7c adjusted according to a corrected electron beam spot shape are formed on the lower voltage side than standing electrodes 3, 4 in a focusing electrode 1. A high-voltage-side end 8 of a final accelerating electrode 2 is shielded by a flat plate having an opening for penetrating an electron beam, and a horizontal flat electrode 9 is mounted so as to project a pair of upper and lower flat plates from vertical ends of this opening in an eaves shape. In the so constituted focusing electrode 1 and the final accelerating electrode 2, electric fields from standing electrodes 3-6 are overlapped on each other to be enlarged, electric fields from the openings 1a, 2a are synthesized with these, and a main electric field forming three main lenses are formed. In addition, lens operations of an opening-type electrode 7 and the horizontal flat electrode 9 are synthesized with this to constitute three main lenses having one center lens and two side lenses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an in-line type electron gun for a color picture tube, and more particularly to a structure of a focusing electrode and a final accelerating electrode capable of obtaining high resolution even at a large current.

[0002]

2. Description of the Related Art In order to improve the resolution of an image of a color picture tube, the diameter of an electron beam spot on the phosphor screen should be reduced, and for that purpose, the diameter of the main lens of the electron gun should be increased. The good is generally known.

[0003] In a conventional in-line type electron gun, for example, disclosed in Japanese Patent Application Laid-Open No. 60-84741, an oblong end face of a focusing electrode 1 and a final accelerating electrode 2 is formed as shown in FIG. Openings 1a and 2a are provided, and further, screen-shaped electrodes 3, 4, 5, and 6 are provided therein.
A method of increasing the lens diameter of a main lens (not shown) by superimposing a lens electric field that focuses three electron beams is adopted. In this case, the shape of the electron beam spot is distorted on the phosphor screen surface, and in order to correct this, an arc-shaped recess is provided on the opposite end side of the partition electrodes 3 to 6.

[0004]

However, in the conventional main lens, when the current value of the electron beam is large, it is difficult to correct the shape of the electron beam spot, and there is a problem that the focus becomes poor at a large current. Was.

Accordingly, an object of the present invention is to provide a large-diameter main lens capable of improving the focus at a large current and reducing the electron beam spot diameter from a small current to a large current.

[0006]

SUMMARY OF THE INVENTION An electron gun for a color picture tube according to the present invention has a tubular first focusing electrode having an oblong opening and the inside of which is divided horizontally into three parts by two screen-like electrodes. And an electron gun for a color picture tube in which a second focusing electrode is arranged to face and forms a main lens, wherein an aperture-type correction electrode for correcting an electron beam spot shape is provided on the low voltage side of the focusing electrode. Are provided in the focusing electrode and in the electric field region of the main lens (claim 1). According to this configuration, the main lens electric field is corrected by the aperture-type correction electrode, and the shape of the electron beam spot on the phosphor screen surface can be made closer to a perfect circle.

It is preferable that the aperture-type correction electrode has a flat plate provided with an aperture having a predetermined shape. According to this configuration, the shape of the opening can be adjusted according to the electron beam spot shape to be corrected. Preferably, the opening is specifically a polygon (claim 3).

Further, it is preferable that a pair of horizontal plate electrodes sandwiching an electron beam from above and below are provided on the focusing electrode on the high voltage side of the focusing electrode and inside the main lens electric field. 4). According to this configuration, the main lens diameter can be increased while increasing the value of the so-called “gun S” to prevent color unevenness on the screen. As a result, not only the shape of the electron beam spot is corrected by the aperture-type correction electrode, but also the main lens having a larger aperture than the conventional one is obtained by the combination of the aperture-type correction electrode and the horizontal plate electrode.

In order to obtain such an effect, the value of the distance from the horizontal center to the end of the horizontal plate electrode is determined by determining the distance between the center of the center lens of the main lens and the center of the side lens. Distance and 1 of the side lens diameter
It is preferable that the value is smaller than the value obtained by adding 3%.

[0010]

FIG. 1 is a schematic view of a focusing electrode and a final accelerating electrode of an electron gun for a color picture tube according to the present invention. The other parts are the same as those of the conventional electron gun, so that illustration and description are omitted. The specific numerical values in the following description are all 32 inches (76 cm).
For the electron gun of the color picture tube for HDTV.

As shown in FIG. 1, the electron gun according to the present invention
The focusing electrode 1 to which the focus voltage is applied and the final accelerating electrode 2 to which a voltage higher than the focus voltage is applied have oblong openings 1a and 2a having long axes in the horizontal direction at opposite end faces thereof. . The screen-shaped electrodes 3 and 4 for electric field correction are provided inside the focusing electrode 1, and the screen-shaped electrodes 5 and 6 are similarly provided inside the final acceleration electrode 2.

The focusing electrode 1 is provided with an aperture-type correction electrode 7 for correcting an electric field in which openings 7a, 7b, 7c of a predetermined shape are formed on a lower voltage side than the screen-shaped electrodes 3, 4. . The shapes of the openings 7a to 7c are appropriately adjusted according to the shape of the electron beam spot to be corrected. FIG. 2 shows an example of the aperture-type correction electrode 7. Opening 7a
7c each have a complex polygonal shape, and have rounded corners to facilitate manufacture of the electrode.

The final accelerating electrode 2 is provided with a pair of horizontal plate electrodes 9 which sandwich the electron beam from above and below on the higher voltage side than the screen-like electrodes 5 and 6. Although the mounting structure is omitted in FIG.
Consists of a pair of upper and lower metal flat plates provided on the high voltage side end face 8 of the final acceleration electrode 2 so as to protrude toward the low voltage side. Specifically, for example, the high voltage side end 8 of the final accelerating electrode 2 is shielded by a flat plate having an opening for passing an electron beam, and a pair of upper and lower flat plates are attached to project from the upper and lower ends of this opening in an eaves shape. In this case, the square opening may be one large rectangular opening common to the three electron beams, or three openings through which each electron beam passes. Further, the horizontal plate electrode 9 is not provided on the final accelerating electrode 2 itself, but the horizontal plate electrode 9 is provided at an end of a separate cylindrical member (not shown). It may be installed on the phosphor screen surface side than the side end surface 8.

The screen-like electrodes 5 and 6 and the horizontal plate electrode 9
It is preferable to arrange them so as to mesh with each other (see FIG. 6) in order to enhance the effect described later. However, the end portions of the screen-shaped electrodes 5 and 6 and the horizontal plate electrode 9 are not engaged with each other.
The same effect can be obtained even if the end portions are separated from each other.

The horizontal plate electrode is not limited to the one divided into three as shown in FIG. 1, but may be an integrated one as shown in FIGS. FIG. 3 is made of a rectangular plate material, and the one shown in FIG. 4 or 5 changes the intensity of the correction electric field by changing the length between the center and the side. In these cases, the screen-like electrodes 5 and 6 and the horizontal flat plate electrode 9 cannot be physically engaged with each other, so that they are arranged apart from each other.

In the focusing electrode 1 and the final accelerating electrode 2 configured as described above, the electric fields of the screen-like electrodes 3 to 6 overlap each other and are extended, and the electric fields of the openings 1a and 2a are combined with each other to form three main lenses. To form a main electric field. Further, the lens function of the aperture type electrode 7 and the horizontal plate electrode 9 is combined to form three main lenses having one center lens and two side lenses.

FIG. 6 shows a focusing electrode 1 and a final accelerating electrode 2.
Is simplified and shown. The position of Z = 0 is the center of the main lens. An example of the dimensions of each part is as follows.
1 = −5 [mm] (lower voltage side than the center of the main lens is defined as minus), distance Z21 to the end of the final acceleration electrode 2 = 5 [mm], screen electrodes 3 and 4 from the center of the main lens Distance Z1 = −2.8 to the low voltage side end
[Mm], distance Z to the ends of the screen-like electrodes 5 and 6
2 = 2.6 [mm], length Z in the Z-axis direction of the horizontal plate electrode 9
22 = 2.5 [mm].

Aperture type correction electrode 7 and horizontal plate electrode 9
Are preferably disposed in the main lens electric field. When the aperture-type correction electrode 7 and the horizontal plate electrode 9 are provided at positions far from the main lens electric field, the shape of the opening of the aperture-type correction electrode 7 becomes more complicated than when the aperture-type correction electrode 7 is provided near the main lens electric field, This is because the same effect cannot be obtained unless the height is made higher.

8 [kV] is applied to the focusing electrode 1 and 29.5 [kV] to the final accelerating electrode 2, and the distance from the center of the main lens to the phosphor screen is 404 [m].
m], a three-dimensional trajectory calculation of the electron beam was performed. FIG. 7 shows the relationship between the position near the main lens and the potential obtained as a result. In the horizontal axis Z of the graph, 0 indicates the center between the focusing electrode 1 and the final accelerating electrode 2, the plus side indicates the high voltage side, and the minus side indicates the low voltage side. The position of the aperture-type correction electrode 7 is Z11 = -5 [mm], and the position of the horizontal plate electrode 9 on the highest voltage side is Z21 = 5 [mm]. As shown in FIG. 7, the aperture-type correction electrode 7 and the horizontal plate electrode 9 are both located in a range where the voltage is changed, that is, in the main lens electric field. The screen-shaped electrodes 3, 4
Is Z1 = −2.8 [mm], the positions of the screen-like electrodes 5 and 6 are Z2 = 2.6 [mm], and the aperture-type correction electrode 7 is
Are located on a lower voltage side than the partition electrodes 3 and 4, and the horizontal plate electrode 9 is located on a higher voltage side than the partition electrodes 5 and 6.

Next, the operation of the aperture type correction electrode 7 will be described. 8 and 9 show the shapes of electron beam spots on the phosphor screen surface. FIG. 8 shows the prior art without the aperture type correction electrode 7, and FIG. 9 shows the present invention with the aperture type correction electrode 7. Shown respectively. The case where the electron beam current is 3 [mA] is shown. If the shape of the electron beam spot is sharp in a specific direction, the electron beam spot diameter in that direction becomes large and the resolution is reduced. As shown in FIG. 9, by providing the aperture-type correction electrode 7, the electron beam spot shape can be made closer to a perfect circle as compared with the related art.

Since the aperture-type correction electrode 7 needs to have a different lens action in an arbitrary direction in accordance with the distorted electron beam spot shape before the aperture-type correction electrode 7 is provided, the apertures 7a to 7c have electron shapes. It becomes a distorted polygon reflecting the beam spot shape (FIG. 2). Therefore, in the case of a perfect circular opening whose lens action cannot be changed in a specific direction or a rectangular opening whose lens action can be changed only in the horizontal and vertical directions, the electron beam spot shape is corrected to a perfect circle. Can not do. The shapes of the openings 7a to 7c are determined by calculation or experiment by appropriately adjusting so as to obtain a desired electron beam spot shape.

Next, the operation of the horizontal plate electrode 9 will be described. In general, the beam movement amount due to the influence of the terrestrial magnetism is inversely proportional to the square of the so-called "gun S". Therefore, the larger the gun S, the more the beam movement amount becomes significantly smaller, and it is possible to prevent color unevenness on the screen. Here, the “gun S” refers to the distance between the center of the center lens and the center of the side lens of the main lens, and coincides with the interval between adjacent electron beams in the main lens. Therefore, it is desirable that the gun S be large in order to prevent color unevenness. But,
A conventional main lens of a type in which a lens diameter of the main lens is increased by superimposing a lens electric field for converging the center beam and the two side beams on each other has an essential characteristic that the lens diameter decreases as the gun S increases. There is. Therefore, it has been difficult to increase both the diameter of the gun S and the lens diameter to achieve both effects. According to the present invention, such restrictions can be resolved.

FIG. 10 shows the relationship between the gun S calculated by calculation and the diameter of the main lens. The straight line a in the drawing is the case of the present invention in which the horizontal plate electrode 9 is provided, and the straight line b is the horizontal plate electrode 9.
In the case of the conventional technology without the provision of, respectively. From the figure, it can be seen that a larger main lens can be obtained with the same size gun S when the horizontal plate electrode 9 is provided. That is, according to the present invention, it is possible to achieve both enlargement of the gun S and enlargement of the main lens.

Next, let X be the distance from the horizontal center to the end of the horizontal plate electrode 9 (FIG. 6). The inventor has found by calculation that the gun S can be made larger when the value of X is set to be smaller than a certain value than when the horizontal plate electrode 9 is not provided. FIG. 11 shows the relationship between X and the gun S obtained by calculation. Gun S without horizontal plate electrode 9
Is 5.45 [mm]. When the horizontal plate electrode 9 is added, the value of the gun S changes, but from FIG.
Only when it is set smaller than 35 [mm]
Is larger than 5.45 [mm]. At this time, the diameter of the side lens remains unchanged at 7 [mm]. That is, X is set to a value smaller than a value obtained by adding 0.9 [mm] of 13 [%] of the side lens diameter to the value of 5.45 [mm] of the gun S when the horizontal plate electrode 9 is not provided. In this case, the size of the gun S can be increased.

Although the electron gun having two focusing electrodes (one of which is a final accelerating electrode) has been described above, the present invention relates to a so-called unipotential type electron gun, and a method of connecting a focus voltage and a high voltage by using a resistor. The present invention can also be applied to an electron gun having three or more focusing electrodes, such as a so-called electric-field-expansion-type electron gun for applying the above-mentioned voltage.

[0026]

According to the present invention, the shape of the electron beam spot can be improved, and the diameter of the main lens can be increased while keeping the gun S large. Since the beam spot diameter can be kept small, it contributes to high image quality and high resolution of a color picture tube, which is increasingly required in the future.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a focusing electrode and a final accelerating electrode of an electron gun for a color picture tube according to the present invention.

FIG. 2 is a diagram showing an aperture-type correction electrode according to the present invention.

FIG. 3 is a perspective view showing a horizontal plate electrode according to the present invention.

FIG. 4 is a perspective view showing a horizontal plate electrode.

FIG. 5 is a perspective view showing the same horizontal flat plate electrode.

FIG. 6 is a schematic plan view of a focusing electrode and a final accelerating electrode according to the present invention.

FIG. 7 is a diagram showing a relationship between a position in a main lens electric field and a voltage according to the present invention.

FIG. 8 is a diagram showing a conventional electron beam spot shape on a phosphor screen surface.

FIG. 9 is a diagram showing an electron beam spot shape on a phosphor screen surface according to the present invention.

FIG. 10 is a diagram showing a relationship between a gun S and a main lens diameter obtained by calculation.

FIG. 11 is a diagram showing a relationship between a distance X and a gun S obtained by calculation.

FIG. 12 is a perspective view showing a focusing electrode and a final accelerating electrode of a conventional electron gun for a color picture tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Focusing electrode 2 Final acceleration electrode 1a, 2a Opening 3-6 Screen-shaped electrode 7 Opening correction electrode 9 Horizontal plate electrode

Claims (5)

[Claims] 1. A first focusing electrode and a second focusing electrode each having an oblong opening and having a horizontal interior divided into three parts by two screen-like electrodes. In the electron gun for a color picture tube to be formed, an aperture-type correction electrode for correcting the shape of an electron beam spot is provided in the first focusing electrode on the low voltage side of the focusing electrode and in the main lens electric field region. An electron gun for a color picture tube. 2. The electron gun for a color picture tube according to claim 1, wherein the aperture-type correction electrode has a flat plate provided with an opening having a predetermined shape. 3. The electron gun for a color picture tube according to claim 2, wherein said opening is polygonal. 4. A pair of horizontal plate electrodes sandwiching an electron beam from above and below are provided on the focusing electrode on the high voltage side of the focusing electrode and inside the main lens electric field. An electron gun for a color picture tube according to any one of the above. 5. A value of a distance from a horizontal center to an end of the horizontal plate electrode is a distance between a center of a center lens and a center of a side lens of the main lens;
The electron gun for a color picture tube according to claim 4, wherein the electron gun is smaller than a value obtained by adding 13% of the side lens diameter.