JPH05299027A - Color cathode-ray tube having in-line type electron gun - Google Patents

Abstract

PURPOSE:To provide a high definition color cathod-ray tube by enlarging a main lens aperture of an in-line type electron gun. CONSTITUTION:Assuming that an electron beam center distance where three electron beams are adjacent to each other is S(mm) and an opening aperture in the direction perpendicular to this electron beam center distance S and the in-line electron beam array direction of two cylindrical electrodes is D(mm), the S and D are set in a relationship of S<5.00, D>S, and 55S-20>=147. Thereby, the three electron beams of an in-line type color electron gun are focused properly, and a main lens aperture can be enlarged within a range where the electron beams do not collide with a plate electrode arranged in an approximately elliptical cylindrical electrode constituting a main lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube equipped with an in-line type electron gun configured to horizontally emit three electron beams toward a phosphor screen.

[0002]

2. Description of the Related Art In an electron gun having a cathode and a plurality of grid electrodes, a cathode ray tube having at least a deflecting device and a fluorescent screen, the following technique is used to obtain a good reproduced image from the central part to the peripheral part of the fluorescent screen. Something like that is known. That is, an astigmatism lens is provided in the area of the electrode forming the focusing lens (main lens) (Japanese Patent Laid-Open No. 53-18866), and the electron beam passage hole of the electrode forming the main lens of the in-line electron gun is vertically elongated. In this case, there are electron beam passage holes of different sizes in the center and the side (JP-A-51-64368).

As shown in FIG. 6, a color cathode ray tube of this type has a vacuum container composed of a panel 61 made of an insulating material such as glass, a funnel 62 and a neck 63, and an electron gun 64 contained in the vacuum container. It has at least a shadow mask 65 and a phosphor screen 66, and reproduces an image by projecting an electron beam emitted from the electron gun 64 onto the phosphor screen 66.

FIG. 7 is a cross-sectional view of a main lens portion for explaining the schematic structure of a conventional in-line type electron gun used for the cathode ray tube. In the figure, 08,09,010
Is a cathode (cathode), 011 is a first grid electrode, 012 is a second grid electrode, 013 is a third grid electrode which is one of the electrodes forming the main lens, and 014 is the other electrode which also forms the main lens. Fourth lattice electrode, 015, 016, 0
Reference numeral 17 denotes an inner cylinder connected to the opening of the third grid electrode 013 on the side of the fourth grid electrode 014, and reference numerals 018, 019 and 020 denote inner cylinders connected to the opening of the fourth grid electrode 014 on the side of the third grid electrode 013. Note that 021, 022, and 023 are the central axes of the respective electron beams, and
Coincides with the axis of the electron gun (tube axis). The central axes 021, 022, 023 correspond to the cathodes 0 of the first grid electrode, the second grid electrode 012, and the third grid electrode, respectively.
Inner cylinders 015, 016, 01 connected to the openings corresponding to 8, 09, 010 and the opening of the third grid electrode 013.
7 are aligned with the central axis of 7, and are arranged substantially parallel to each other on a common plane.

The central axis of the fourth grid electrode 014 and the center axis of the inner cylinder 019 connected to it coincides with the central axis 022, but both side openings and the inner cylinders 018 connected to these openings. The central axes of 020 do not coincide with the corresponding central axes and are slightly displaced outward. The in-line type electron gun having the above structure operates as follows.

Three cathodes 0 heated by heaters
The thermoelectrons emitted from 8, 09, 010 are applied to the first grid electrode 01 by the positive voltage applied to the second grid electrode 012.
The electron beam is attracted to one side and three electron beams are formed. Then, these three electron beams pass through the openings of the first grid electrode 011 and then the openings of the second grid electrode 012, and then the third grid electrode 013 and the fourth grid electrode 014.
Enters the main lens while being accelerated by the positive voltage applied to.

Here, a low voltage of about 5 to 10 kV is applied to the third lattice electrode 013 constituting the main lens, and a high voltage of about 20 to 35 kV is applied to the fourth lattice electrode 014. Therefore, the third grid electrode 013 to which the low voltage is applied and the fourth grid electrode 014 to which the high voltage is applied
The third grid electrode 013 and the fourth grid electrode 013
An electrostatic field is formed between the grid electrodes 014. Therefore, the trajectories of the three electron beams supplied to the main lens are bent by the electrostatic field. As a result, the three electron beams are focused on the phosphor screen.

Further, since the corresponding side openings of the third lattice electrode 013 and the fourth lattice electrode 014 do not coincide with the central axis of the cylindrical portion, the side main lens is not symmetrical with respect to the central axis. Therefore, the electron beam on the side is deflected inward so as to coincide with the central electron beam on the fluorescent screen. As a result, the three electron beams are concentrated on the phosphor screen, and the three-color images of R, G, and B by the respective electron beams are correctly superimposed and a color image is displayed.

[0009]

In the in-line type electron gun configured as described above, the three electron beams deviate from the concentration condition due to slight variations in the precision and assembly precision of the electron gun parts. It is necessary to make another adjustment to concentrate the electron beam. In this concentrated adjustment, the smaller the distance S between the centers of the electron beams, the smaller the deviation from the above-mentioned concentrated condition, and the easier the adjustment work. From the results of conventional experiments, it has been found that it is desirable to set this S value to less than approximately 5 mm.

However, in the conventional focusing electrode structure, the aperture diameter of the focusing electrode is limited to be smaller than the center distance S of the adjacent electron beams incident on the lens, and the center distance S of the electron beams is less than 5 mm. There is a limit to the aperture diameter.
Since the effective aperture of the focusing lens of each electron beam is determined by this aperture diameter, if this aperture diameter is small, the spherical aberration associated with the small diameter lens becomes large, and the electron beam spot diameter becomes large.

In order to solve such a problem, a structure disclosed in Japanese Patent Laid-Open No. 58-103752 is known. According to this structure, spherical aberration can be reduced while keeping the center-to-center distance S between adjacent electron beams to be less than 5 mm. The schematic structure of the electron gun disclosed in the above publication will be described with reference to FIG. FIG. 1A is a longitudinal sectional view of a main part for explaining a main lens part of an in-line type electron gun,
(B) is a cross-sectional view seen from the AA ′ direction in (a).

In the figure, 13 is a cylindrical third grid electrode having an open elliptical cross section, 14 is a cylindrical fourth grid electrode having an open elliptical cross section, and 13-1 is a third grid electrode. A flat plate electrode installed inside the grid electrode 1, 14-1 is a flat plate electrode installed inside the fourth grid electrode 2, 13R, 13G, 1
3B is an electron beam passage hole (opening) of the flat plate electrode 13-1, 14R, 14G, 14B is an electron beam passage hole (opening) of the flat plate electrode 14-1, 21 and 22, 23 are central axes.

As shown in FIG. 1B, the openings 13R of the plate electrode 13-1 installed inside the third grid electrode 1 are
The diameter D in the direction (vertical direction) orthogonal to the in-line direction (horizontal direction) of 13G and 13B is substantially equal to the diameter of the main lens formed by this electrode. The larger the value of the diameter D (mm) is, the smaller the spherical aberration is, and the electron beam spot diameter is valued.

However, even with the above structure, the following new problems occur. That is, in order to increase the vertical diameter D and reduce the electron beam spot diameter,
It is necessary to expand the electron beam diameter within the main lens electrode.
At this time, if the diameter D in the vertical direction is too large with respect to the center-to-center distance S between the adjacent electron beams, there arises a problem that the electron beam collides with the flat plate electrode in the electrode especially at a large current.

An object of the present invention is to provide an in-line type in which the diameter of the main lens can be increased without causing a problem in the concentration of three electron beams and in the range where the electron beam does not collide with the plate electrode inside the third lattice electrode. It is to provide a cathode ray tube equipped with an electron gun.

[0016]

To achieve the above object, the present invention provides an electron beam generating means for generating three electron beams in an in-line arrangement toward a fluorescent screen, and an electron beam emitted from the electron beam generating means. The two plate-shaped electrodes having an electron beam passage region are provided inside each of the two cylindrical electrodes which are arranged at intervals in the traveling direction of the electron beam and have a substantially oval opening cross section kept at different potentials. In a color cathode ray tube equipped with an in-line type electron gun having at least a main lens means for focusing the three electron beams on the phosphor screen, the distance between adjacent electron beam centers of the three electron beams is S. (Mm), where S (5.00) is the distance S between the electron beam centers and D (mm) is the opening diameter of the two cylindrical electrodes in the direction perpendicular to the in-line electron beam arrangement direction. It is characterized in that the above S and D are set in a relationship of D> S and 55S-20D ≧ 147.

Further, the two cylindrical electrodes forming the main lens means are opposed to each other, and the openings are opposed to each other by a single opening for the three electron beams.

[0018]

With the above structure, it is possible to prevent problems from being caused by the concentration of the three electron beams. And
The structure shown in FIG. 1 is used for the main lens, and the diameter D in the vertical direction with respect to the arrangement of the three electron beams in the opening of the cylindrical electrode whose opening cross section is substantially elliptical is the diameter of the main lens formed by this electrode. Therefore, by making the diameter D in the vertical direction larger than the distance S between the centers of adjacent electron beams, the diameter of the main lens can be made larger than that of the conventional structure, spherical aberration can be reduced, and the diameter of the electron beam spot can be made smaller than that of the conventional structure. Can be made smaller.

In the in-line type electron gun, in order to effectively use the diameter of the main lens, the diameter of the electron beam supplied to the main lens must be increased as the diameter of the main lens increases. This is to suppress the expansion of the electron beam spot on the phosphor screen due to the space charge effect. However, if the diameter of the electron beam in the main lens is too large, the diameter of the electron beam spot is increased due to lens aberration. That is, there is an optimum value for the electron beam diameter in the main lens.

FIG. 2 is an explanatory view showing the relationship between the lens aperture and the optimum value of the electron beam diameter to be supplied to the lens. In the figure, a color cathode ray tube with a screen effective diagonal size of 51 cm and a deflection angle of 90 ° is shown. The analysis values are shown for a 4-lattice electrode voltage of 25 kV, a third lattice electrode voltage of 7 kV, and a beam current value of 4 mA. It can be seen from the graph of this explanatory diagram that the optimum value of the electron beam diameter increases as the lens aperture increases.

On the other hand, in the electron gun having the main lens structure as shown in FIG. 1, the diameter D in the vertical direction with respect to the arrangement of the three electron beams in the opening is large with respect to the distance S between the centers of the adjacent electron beams. If it passes, the diameter of the electron beam to be supplied to the main lens needs to be increased correspondingly, and the electron beam collides with the flat plate electrode inside the cylinder at the time of a large current.
FIG. 3 is an explanatory diagram showing the relationship between the center-to-center distance S of adjacent electron beams and the maximum value of the electron beam diameter in the main lens where the electron beam does not collide with the flat plate electrode installed inside the cylindrical electrode. Thus, the electron beam does not collide with the plate electrode in the range of the shaded area where the electron beam diameter is smaller than the value shown by the solid line in the figure.

From the facts shown in FIGS. 2 and 3, the relationship between the optimum value of the lens aperture and the distance S between the centers of the adjacent electron beams can be obtained. The lens aperture corresponds to the vertical diameter D of the opening of the cylindrical grid electrode. From this, the relationship between the center-to-center distance S between the adjacent electron beams and the vertical diameter D of the opening of the tubular lattice electrode can be obtained. FIG. 4 is an explanatory diagram showing the relationship between the center-to-center distance S between the adjacent electron beams and the vertical direction diameter D of the opening of the cylindrical grid electrode.
Is the relationship between the S dimension and the D dimension obtained from the relationship between FIGS. 2 and 3, and b is a straight line of S = D.

That is, the relationship between the lens aperture D and the maximum value Xr of the electron beam diameter supplied to the lens is approximately 55Xr-20D = 30 (1). Further, the region showing the maximum value Xr of the electron beam diameter in the main lens where the electron beam does not collide with the plate electrode installed inside the cylindrical electrode with respect to the distance S between the centers of the adjacent electron beams in FIG. , Xr ≦ S−2.1 (2)

From the above formulas (1) and (2), the maximum value Xr of the electron beam diameter is deleted, and the electron beam does not collide with the flat plate electrode installed inside the cylindrical electrode. A region showing the relationship between the center-to-center distance S and the lens aperture D is 55S-20D ≧ 147 (3).

The diameter of the electron beam spot on the fluorescent screen can be increased by enlarging the lens aperture to the limit where the electron beam does not collide with the flat plate electrode installed inside the cylindrical electrode at the time of a large current in the range below this straight line. Can be reduced. Then, the lens aperture D can be made larger than the center-to-center distance S between the adjacent electron beams in the above-mentioned region and a region restricted by S = D (region shown by diagonal lines in FIG. 4).

As described above, in the electron gun having the structure shown in FIG. 1, the value of the desired lens aperture D and the center-to-center distance S between adjacent electron beams is in the shaded region in FIG. By setting the relationship between the lens aperture D and the center-to-center distance S of the adjacent electron beams in the shaded area in FIG. 4, the electron beam is generated at a large current without causing a problem in the concentration of the three electron beams. The diameter of the main lens can be made larger than in the conventional case within a range in which it does not collide with a flat plate electrode installed inside a cylindrical electrode having an opening cross section of a substantially elliptical shape.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 5 is a sectional view of an essential part showing a main lens portion of an electron gun for explaining an embodiment of a cathode ray tube equipped with an in-line type electron gun according to the present invention.
(A) is a longitudinal sectional view taken along the in-line direction, (b) is a lateral sectional view taken along the line AA 'of (a), and (c) is (a).
FIG. 6 is a horizontal cross-sectional view taken along the line BB ′ of FIG.

In the figure, 13 is a third grid electrode which constitutes the main lens, 13-1 is a flat plate electrode installed inside the third grid electrode 13, and 13R, 13G and 13B are electron beam passage holes for the respective color electron beams. , 14 is a fourth lattice electrode which constitutes the main lens, 14-11 is a plate electrode installed inside the fourth lattice electrode 14, and 14R, 14G and 14B are electron beam passage regions of the respective color electron beams.

The central electron beam passage region 14G of the plate electrode 14-11 is an opening, and the side electron beam passage regions 14R and 14B are notches of the plate electrode 14-11 and the inner wall of the fourth lattice electrode 14. It is an electron beam passage hole surrounded by. In addition, the third grid electrode 13 and the fourth grid electrode 1
The openings of No. 4 have the same shape. In addition, the same reference numerals as those in FIG. 1 correspond to the same parts.

In the figure, the center-to-center distance S of the adjacent electron beams incident on the main lens is 4.75 mm, and the openings of the third and fourth lattice electrodes 13 and 14 are perpendicular to the arrangement of the three electron beams. The diameter D is 5.5 mm. In the case of the above dimensions, the center-to-center distance S between adjacent electron beams incident on the main lens, the third lattice electrode 13 and the fourth lattice electrode 1
The relation of the diameter D in the vertical direction with respect to the arrangement of the three electron beams in the opening of No. 4 is included in the shaded area in FIG. At this time, the spherical aberration of the main lens is almost the same as the spherical aberration of the lens having a cylindrical structure with a diameter of 5.5 mm, and there is no problem in concentrating the three electron beams, and the electron beam at a large current is used. Does not collide with the plate electrode 13-1 installed inside the third lattice electrode 13, and the diameter of the electron beam spot can be greatly reduced as compared with the conventional case.

[0031]

As described above, according to the present invention, in a color cathode ray tube equipped with an in-line type electron gun, a vertical direction with respect to three electron beams passing through the electrostatic focusing electrodes forming the main lens of the electron gun. It is possible to provide a large-diameter lens with a proper diameter and to provide a color cathode ray tube capable of reproducing a high-definition image.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an essential part of an electron gun applied to a color cathode ray tube including an in-line type electron gun according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a lens aperture and an optimum value of an electron beam diameter supplied to a lens.

FIG. 3 is an explanatory diagram showing a relationship between a center-to-center distance S between adjacent electron beams and a maximum value of an electron beam diameter in a main lens in which the electron beam does not collide with a flat plate electrode installed inside a cylindrical electrode. is there.

FIG. 4 is an explanatory diagram showing a relationship between a center-to-center distance S between adjacent electron beams and a vertical diameter D of an opening of a cylindrical lattice electrode.

FIG. 5 is a cross-sectional view of a main part of a main lens portion of an electron gun for explaining an embodiment of a cathode ray tube including the in-line electron gun according to the present invention.

FIG. 6 is a sectional view illustrating a schematic structure of an in-line type color cathode ray tube to which the present invention is applied.

7 is a cross-sectional view of a main lens portion for explaining a schematic structure of a conventional in-line type electron gun used for the cathode ray tube shown in FIG.

[Explanation of symbols]

13 Third Lattice Electrode 14 Fourth Lattice Electrode 13-1 Plate Electrode Installed Inside Third Lattice Electrode 14-1 Plate Electrode Installed Inside Fourth Lattice Electrode 13R, 13G, 13B Electrons of Plate Electrode 13-1 Beam passing hole (opening) 14R, 14G, 14B Electron beam passing hole (opening) of flat plate electrode 14-1, 21, 22, 23 Center axis 14-11 Flat plate electrode 14R, 14G installed inside fourth grid electrode , 14B Electron beam passing area of each color electron beam 61 Panel 62 Funnel 63 Neck 64 Electron gun 66 Phosphor screen

Claims (1)

[Claims] 1. An electron beam generating means for generating three electron beams in an in-line arrangement toward a fluorescent screen and an electron beam emitted from the electron beam generating means are arranged at intervals with different potentials. A main lens for focusing the above three electron beams on the fluorescent surface by providing plate electrodes having electron beam passage areas inside each of two tubular electrodes having a substantially oval opening cross section held at In the color cathode-ray tube equipped with an in-line type electron gun, the distance between adjacent electron beam centers of the three electron beams is S (mm). When the aperture diameter of the cylindrical electrode in the direction perpendicular to the in-line electron beam arrangement direction is D (mm), S <5.00 D> S and 55S-20D ≧ 147 Color cathode ray tube having an in-line type electron gun, characterized in that setting the D.