JPH08190873A - Electron gun and cathode-ray tube - Google Patents

Abstract

PURPOSE: To set the sectional form of the luminescent line at electron beam scanning into a prescribed form, suppress the opening breakage at electron gun assembling, and regenerate a high quality image by providing prescribed openings on a control grid electrode and a shielding grid electrode. CONSTITUTION: Openings 8 (8a, 8b, 8c) which are electron beam passing holes formed on a control grid electrode 2 are arranged in conformation to the arranging direction of a cathode, and each opening has a form in which a circular arc is combined to each side of a square. The openings 11 (11a, 11b, 11c) of a shielding grid electrode 3 are arranged opposite to the openings 8a, 8b, 8c of the electrode 2, respectively, and have a circular form. Thus, a beam spot form on a screen is made substantially square to make the build-up inclination of the luminescent line at electron beam scanning into a sharp rectangular sectional form, and the resolution of image can be improved. Further, since the deformation or breakage of the opening at electron gun assembling is avoided, and the generating potential of cold emission can be reduced to perform a stable operation, the reliability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun and a cathode ray tube equipped with this electron gun, and in particular, improves focus characteristics over the entire fluorescent screen and in the entire current range of the electron beam to obtain good resolution. The present invention relates to an electron gun and a cathode ray tube which can be used.

[0002]

2. Description of the Related Art A color cathode ray tube having a plurality of in-line arranged electron beams is widely used as an image display means of a television receiver or a monitor terminal.

The electron gun used in this type of cathode ray tube is
For example, as disclosed in JP-B-4-27656, a plurality of cathodes, a control grid electrode, a shield grid electrode, and at least one concentrated electrode are arranged in this order,
It is configured to generate electrons from each of the cathodes and project the electrons in the form of beams along a common plane including the plurality of beam paths.

The control grid electrode has a plurality of circular apertures as many as the cathodes, and the shield grid electrode has the same number as the cathodes across a common plane containing the plurality of beam paths. A first plate-shaped portion having a circular aperture and a second rectangular recessed portion that is elongated in the array direction of the plurality of cathodes and extends in a common plane including the plurality of beam paths. And a plate-shaped part.

Each of the circular apertures penetrates the first plate-shaped portion and the direction in which the plurality of cathodes are arranged (generally, the horizontal direction).
It extends to the bottom of the rectangular recess that extends in a slender shape.
The rectangular recesses elongated in the array direction of the plurality of cathodes are arranged on the control grid electrode side of the shield grid electrode.

The ratio of the width and depth of the rectangular recessed portions in the array direction of the plurality of cathodes to each direction (generally the vertical direction) is in the range of 2 to 5, and the second The thickness of the plate-like portion is within the range of 0.24 to 0.8 times the diameter of each circular aperture formed in the first plate-like portion, and the beam (hereinafter, also referred to as electron beam) is With respect to the concentration in the common plane including the plurality of beam paths, the structure causes a lack of concentration in the plane perpendicular to the common plane including the plurality of electron beam paths.

As another conventional technique, for example, in a cathode ray tube disclosed in Japanese Patent Publication No. 4-33099, at least one electron beam is generated in the neck of a vacuum envelope composed of a panel, a funnel and a neck. An electron gun for drawing a raster by deflecting the focused beam spots in two directions, horizontal and vertical, on a display screen formed on the panel is provided.

In the electron gun, the cathode is centered with respect to the tube axis of the vacuum envelope, the first grid electrode is arranged opposite to the cathode, and is separated from the first grid electrode by a certain distance. A second grid electrode arranged, and the first grid electrode and the second grid electrode each have a portion which is perpendicular to the tube axis and includes an electron beam passage hole (opening), The aperture of the first grid electrode is elongated in one deflection direction, and the aperture of the first grid electrode on the cathode side is also elongated in the other deflection direction. The dimension of the aperture on the cathode side in the longitudinal direction is the second grid electrode. Be at least equal to the width dimension of the side aperture.

[0009]

In the conventional electron gun for a cathode ray tube described above, as shown in FIG. 21 (a), the beam spot shape on the screen is substantially circular, and the electron beam is deflected. When raster scanning is performed, the cross-sectional shape of the locus of the beam spot (the locus of the bright line) has a gentle slope profile having a peak in the center as shown in FIG.

Therefore, there is a problem that the outline of the bright line of the electron beam spot on the screen is not clear, and the apparent definition is deteriorated, so that the so-called resolution is lowered.

Generally, in order to make the image on the screen clear, it is desirable that the cross-sectional shape of the bright line when scanned with an electron beam is close to a rectangular profile with a steep rising slope.

As one means for achieving this, as disclosed in Japanese Patent Publication No. 4-33099, there is a method in which the aperture shape of the control grid electrode is rectangular, and the shape of the beam spot on the screen is changed. The cross-sectional shape of the bright line when beam scanning is performed as a rectangle can be made close to a rectangular profile with a steep rising slope.

In general, however, since an electron gun has a plurality of electrodes arranged in a predetermined relationship, a circular or elliptical reference rod inscribed on the inner surface of each electrode is inserted into the plurality of electrons to form a plurality of electrons. It is fixed and assembled by sandwiching it between two glasses (so-called beading glass) from a direction perpendicular to the plane formed by the beam.

At the time of this assembly, the two glasses are heated and melted in a suitable state by a gas burner or the like, and the electrodes are momentarily pressed from both sides, so that a part of the electrodes is driven into the glass and fixed. . After cooling, the reference rods are pulled out to arrange the electrodes in a predetermined relationship.

In such an assembling method, when the control grid electrode has a rectangular opening as in the prior art, the reference rod and the rectangular opening are in contact with a circular or elliptical vertex and a rectangular side. , The contact part of the aperture is locally deformed or destroyed by the impact that the electrode receives when the glass is pressed against the electrode or the friction between the aperture and the reference rod that occurs when the electrode is inserted into or pulled out from the reference rod. As a result, a protrusion is formed on the edge of the opening.

Therefore, the electric field is concentrated on the protrusions to cause cold emission, causing a problem that the screen is caused to emit light regardless of the image signal.

A first object of the present invention is to solve the above-mentioned problems of the prior art, to make the rising slope of the cross-sectional shape of the bright line when scanning the screen with an electron beam close to a steep rectangular profile, and further to provide an electron gun. An object of the present invention is to provide an electron gun capable of reproducing a high-quality image by suppressing breakage or deformation of an opening that occurs during assembly of the.

A second object of the present invention is to provide a cathode ray tube using the above electron gun.

[0019]

In order to achieve the first object, the first invention according to claim 1 is to provide a plurality of cathodes, a control grid electrode, a shield grid electrode, and at least one concentrated electrode. In the electron gun arranged in this order to project electrons generated from each of the plurality of cathodes in the form of a plurality of beams along a common plane. With a plurality of openings corresponding to the cathode, at least one of the openings is an arc in the center of each of the four sides of the rectangle, the center of at least two arcs facing each other of the arc It is characterized in that the shape matches the center of the rectangle.

In order to achieve the above first object,
According to a second aspect of the present invention, a plurality of cathodes, a control grid electrode, a shield grid electrode, and at least one concentrating electrode are arranged in this order to generate a plurality of electrons generated from each of the plurality of cathodes. In an electron gun configured to project in a beam shape along a common plane, the control grid electrode and the shield grid electrode have a plurality of holes corresponding to the plurality of cathodes, and the control grid electrode has a hole. The shield grid electrode has a rectangular shape and has a concave portion around the aperture whose width in the direction perpendicular to the plane including the plurality of beam paths is wider than that in the direction parallel to the plane. The opening is a part of the center of each of the four sides of the rectangle is an arc, the center of at least two arcs facing each other of the arc is a shape that matches the center of the rectangle, and around the opening. A plane containing the plurality of beam paths Wherein the parallel direction of the width is a shape having a wide recess with respect to the plane than the vertical width for.

Further, in order to achieve the above-mentioned second object, a third invention according to a third aspect of the present invention is a panel portion having a phosphor screen, a neck portion for accommodating an electron gun, and the panel portion and the neck. A vacuum envelope consisting of a funnel part connecting the parts, an electron gun for emitting a plurality of electron beams contained in the neck part in an in-line arrangement, and a transition region between the funnel part and the neck part of the vacuum envelope part. In a cathode ray tube having at least an exterior deflection device, the electron gun comprises a plurality of cathodes, a control grid electrode, a shield grid electrode,
And at least one concentrated electrode are arranged in this order so as to project electrons generated from each of the plurality of cathodes in the form of a plurality of beams along a common plane, and the control grid electrode and the shield grid electrode Has a plurality of openings corresponding to the plurality of cathodes, at least one of the openings is an arc in the center of each of the four sides of the rectangle, at least two arcs facing each other of the arc. It has a shape whose center coincides with the center of the rectangle.

Further, in order to achieve the above-mentioned second object, a fourth invention according to a fourth aspect is that a panel portion having a phosphor screen, a neck portion for accommodating an electron gun, and the panel portion and the neck are provided. A vacuum envelope consisting of a funnel part connecting the parts, an electron gun for emitting a plurality of electron beams contained in the neck part in an in-line arrangement, and a transition region between the funnel part and the neck part of the vacuum envelope part. In a cathode ray tube having at least an exterior deflection device, the electron gun comprises a plurality of cathodes, a control grid electrode, a shield grid electrode,
And at least one concentrated electrode are arranged in this order so as to project electrons generated from each of the plurality of cathodes in the form of a plurality of beams along a common plane, and a control grid electrode of the electron gun. The shield grid electrode has a plurality of apertures corresponding to the plurality of cathodes, the aperture shape of the control grid electrode is rectangular, and parallel to a plane including the plurality of beam paths around the aperture. Has a recess whose width in the direction perpendicular to the plane is wider than the width in the above direction, and the opening of the shielding grid electrode is an arc in a part of each of the four sides of the rectangle
The center of at least two arcs facing each other among the arcs has a shape coinciding with the center of the rectangle, and has a width in a direction perpendicular to a plane including the plurality of beam paths around the aperture. It is characterized by having a recess having a wide width in a direction parallel to the plane.

[0023]

In the structure of the first aspect of the invention, at least one of the control grid electrode and the shield grid electrode having a plurality of openings corresponding to a plurality of cathodes is provided with a part of the central portion of each of the four sides of the rectangle. Is a circular arc, and the center of at least two arcs facing each other among the circular arcs coincides with the center of the rectangle, so that the opening of the lattice electrode due to the insertion or removal of the reference rod during the assembly of the electron gun Collision with or friction with is avoided, the contact portion of the opening is not locally deformed or destroyed to form a protrusion on the edge of the opening, and the cold emission as in the conventional technique does not occur. The electron gun can be prevented and can achieve high-quality image display.

In the structure of the second aspect of the invention, the rectangular aperture of the control grid electrode having a plurality of apertures corresponding to the plurality of cathodes, and the plurality of beam paths around the aperture. A recess having a wider width in the direction perpendicular to the plane than the width in the direction parallel to the plane is included, and a part of each central portion of the four sides of the rectangle is an arc in the shielding grid electrode.
An opening having a shape in which the centers of at least two arcs facing each other among the arcs coincide with the center of the rectangle, and a width in a direction perpendicular to a plane including the plurality of beam paths around the opening is more than By forming the recess having a wide width in the direction parallel to the plane, deformation and destruction of the openings of the grid electrode are avoided, and the formed on the screen when the electron beam is scanned. It is possible to obtain an electron gun in which the sharpness, that is, the resolution of a display image is improved as a rectangular profile in which the beam spot has a substantially rectangular shape and the bright line has a sharp rising slope.

Further, in the structure of the third invention,
The opening of at least one of the plurality of openings corresponding to the plurality of cathodes formed in the control grid electrode and the shield grid electrode of the electron gun is the opening of the grid electrode. A high-quality and high-resolution cathode ray tube can be obtained by having a shape in which the centers of at least two arcs facing each other among the arcs coincide with the center of the rectangle.

Then, in the configuration of the above-mentioned fourth invention,
The control grid electrode and the shield grid electrode of the electron gun are provided with a plurality of openings corresponding to the plurality of cathodes, the opening shape of the control grid electrode is rectangular, and the plurality of beams are provided around the openings. A recess whose width in the direction perpendicular to the plane is wider than the width in the direction parallel to the plane including the path is formed, and the opening of the shielding grid electrode is formed by an arc in each of the central portions of the four sides of the rectangle. , With a shape in which the centers of at least two arcs facing each other among the arcs match the center of the rectangle,
A high-quality and high-resolution cathode ray is formed by providing a concave portion having a width in the direction parallel to the plane wider than the width in the direction perpendicular to the plane including the plurality of beam paths around the opening. You can get a tube.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a constitutional example of an electron gun to which the present invention is applied, showing a constitution of a so-called unipotential-bipotential type electron gun.

In the figure, 1a, 1b and 1c are cathodes, 2 is a control grid electrode (G1), 3 is a shield grid electrode (G2), 4 is a third grid electrode (G4), and 5 is a fourth grid electrode.
The grid electrodes (G5) and 6 are fifth grid electrodes (G6), 7 is a sixth grid electrode (G7), and 7a is a shield cup, which are arranged at a predetermined interval and positional relationship.

The cathodes 1a, 1b, 1c are arranged in a line (in-line) in a common plane, and the control grid electrode 2 and the shield grid electrode 3 constitute a three-pole portion, and the cathodes 1a, 1b, 1c.
The electrons generated in 1 are formed into a beam and emitted to the lattice electrode group in the subsequent stage.

The third grid electrode 4, the fourth grid electrode 5, the fifth grid electrode 6 and the sixth grid electrode 7 are focusing electrodes,
The grid electrode 4, the fourth grid electrode 5, and the fifth grid electrode 6 form a unipotential type main lens, and the fourth grid electrode 5, the fifth grid electrode 6, and the sixth grid electrode 7 form a bipotential type main lens. Make up.

During operation of the cathode ray tube, approximately 0 V is applied to the first grid electrode 2, approximately 400 to 1500 V is applied to the second grid electrode 3 and the fourth grid electrode 5, and the third grid electrode 4 is used. About 5 kV to 10 kV is applied to the fifth grid electrode 6, and the sixth
An anode voltage of about 20 kV to 35 kV is applied to the grid electrode 7. The shield cup 7a is the sixth grid electrode 7
It is attached to and shields the deflection magnetic field to the electron beam.

FIG. 2 is a front view of the first grid electrode for explaining the first embodiment of the electron gun according to the present invention, viewed from the side of the second grid electrode, where 2 is the first grid electrode, 8 (8a, 8b, 8c)
Is an opening (electron beam passage hole).

FIG. 3 is an enlarged front view of the opening of the first grid electrode viewed from the side of the second grid electrode, where 8 is the opening (8
a, 8b, 8c), 9 is a square, 10a, 10b, 10
c and 10d are arcs.

The openings 8 (8a, 8b, 8c), which are electron beam passage holes in which the first grid electrode 2 shown in FIG. 2 is formed, are arranged corresponding to the arrangement direction of the cathodes 1a, 1b, 1c,
As shown in FIG. 3, each opening has a shape in which each side of the square 9 is combined with arcs 10a, 10b, 10c and 10d.

The radii of the four arcs formed on the four sides are the same, and their centers coincide with the center of the square 9.

FIG. 4 is a front view of a second grid electrode for explaining the first embodiment of the electron gun according to the present invention as viewed from the side of the first grid electrode, and 3 is the second grid electrodes 11a, 11b and 11c.
Is an opening (electron beam passage hole).

In the figure, the opening 11 of the second grid electrode 3 is formed.
a, 11b, 11c are openings 8a, 8b of the first grid electrode,
8c are arranged so as to face each other, and the shape is circular.

In the electron gun equipped with the first and second grid electrodes 2 and 3, the electron beam has a substantially rectangular cross section, and the screen-shaped beam spot has a rectangular cross section with a steep rising slope, resulting in a clear image. The degree improves.

FIG. 5 is an explanatory view of a raster formed on the screen of the cathode ray tube using the electron gun of the first embodiment of the present invention, (a) is an example of displaying an image (numeral 8),
(B) shows the profile of the bright line.

As shown in FIG. 6B, the profile of the bright line of the beam spot according to this embodiment has a steep rising slope, and the sharpness of the image (a) is high, so that a high-resolution image display is possible. It will be possible.

FIG. 6 is a top view of an assembly jig for assembling the electron gun of the first embodiment according to the present invention, FIG. 7 is a side view thereof, and 12a, 12b and 12c are reference rods and 12
d is a base.

This assembly jig comprises a base 12d and three reference rods 12a, 12b and 12c which are erected. The cross-sections of the reference rods 12a, 12b and 12c are the opening diameters of the grid electrodes which are sequentially stacked. It has almost the same shape.

FIG. 8 is a sectional view of an essential part for explaining a state in which the opening of the first grid electrode in the first embodiment of the electron gun according to the present invention is inserted into the reference rod of the assembly jig shown in FIGS. There are openings 8 and reference rods 12.

As shown in the figure, the reference rod 12 has an opening 8
Since the reference rod 12 does not push up the opening 8 or come into contact with it due to excessive friction, it is not deformed or destroyed near the opening of the electrode.

Therefore, it is possible to greatly reduce the potential for generating cold emission as in the conventional technique.

FIG. 9 is a front view of a first grid electrode for explaining the second embodiment of the electron gun according to the present invention, viewed from the side of the second grid electrode, where 2 is the first grid electrode, 13 (13a, 13b,
13c) is an opening (electron beam passage hole).

In addition, FIG. 10 shows the openings of the first grid electrode as the second
It is an enlarged front view seen from the grid electrode side, 13 is an opening (13a, 13b, 13c), 14 is a square, 15a,
15b, 15c and 15d are arcs.

An opening 13 (13a, 13b, 1) which is an electron beam passage hole in which the first grid electrode 2 shown in FIG. 9 is formed.
3c) The openings are arranged in correspondence with the arrangement direction of the cathodes 1a, 1b, 1c shown in FIG. 1, and the shape of each opening is, as shown in FIG. 15
The shape is a combination of b, 15c, and 15d.

The radii of the four arcs formed on the four sides are the same, and their centers coincide with the centers of the squares 14.

FIG. 11 is a front view of a second grid electrode for explaining the second embodiment of the electron gun according to the present invention as seen from the side of the first grid electrode, and 3 is the second grid electrode, 16a, 16b, 16
Reference numeral c is an opening (electron beam passage hole). FIG. 12 is an enlarged front view of the openings of the second grid electrode.

In the figure, the openings 16 of the second grid electrode 3 are formed.
a, 16b, 16c are openings 13a, 13 of the first grid electrode
b, 13c are arranged so as to face each other, and the shape is such that the arcs 18a, 18b, 18 are formed on each side of the square 17.
The shape is a combination of c and 18d.

The radii of the four arcs formed on the above four sides are the same, and the center thereof coincides with the center of the square 17.

In the electron gun provided with the first grid electrode 2 and the second grid electrode 3, the electron beam has a cross section close to a square due to the synergistic effect of each opening shape of the first grid electrode 2 and the second grid electrode 3. Therefore, the screen-shaped beam spot has a rectangular cross section with a rising slope more steep than that of the first embodiment, and the sharpness of the image is further improved.

FIG. 13 is a front view of the first grid electrode for explaining the third embodiment of the electron gun according to the present invention as viewed from the second grid electrode side, and 2 is the first grid electrode, 19 (19a, 19).
b and 19c) are holes (electron beam passage holes).

In addition, FIG. 14 shows the opening of the first grid electrode
FIG. 15 is an enlarged front view seen from the grid electrode side, and FIG.
It is a principal part sectional drawing along the A line.

In this embodiment, the opening 19 is a square 20 having rounded corners, and a concave portion (slit) 21 having a wider width in a direction perpendicular to a width parallel to a surface formed by a plurality of electron beams. It is equipped with.

FIG. 16 shows the third embodiment of the electron gun according to the present invention.
FIG. 17 is a front view of a second grid electrode for explaining the embodiment as seen from the first grid electrode side, FIG. 17 is an enlarged front view of the openings of the second grid electrode as seen from the first grid side, and FIG. 18 is B- of FIG. It is sectional drawing along the B line.

Further, the openings 22 (22 of the second grid electrode 3)
a, 22b, 22c) is a combination of holes of a square 23 having rounded corners and arcs 24a, 24b, 24c, 24d, and the central portion of each of the four sides of the square 23 is an arc. Moreover, the radii of these four arcs are the same, and the center thereof coincides with the center of the square 23.

Further, there is provided a recess 25 around the opening, the width of which in the direction parallel to the plane formed by the plurality of electron beams is wider than the width in the direction perpendicular thereto.

In such a structure, the cross section of the electron beam generated from the cathode becomes rectangular due to the synergistic effect of the aperture shapes of the first and second lattice electrodes 2 and 3, and the screen of the cathode ray tube was scanned. At this time, the emission line cross-sectional shape of the beam spot becomes a rectangular profile having a steep rising slope, and the sharpness of the image is improved.

Further, the first grid electrode 2 and the second grid electrode 3
The concave portion formed in each aperture forms an astigmatic electric field in which the concentration of the electron beam is insufficient in the direction perpendicular to the direction parallel to the surface formed by the plurality of electron beams. As a result, the electron beam is less likely to enter the eccentric aberration part of the main lens of the electron gun when horizontally deflected, and the image quality on the entire screen can be improved.

FIG. 19 is a side view for explaining an example of an electron gun according to the present invention, in which 1 is a cathode, 2 is a first lattice electrode, and 3
Is a second grid electrode, 4 is a third grid electrode, 5 is a fourth grid electrode, 6 is a fifth grid electrode, 7 is a sixth grid electrode, 8 is a shield cup, and 26 is electrode fixing glass (beading glass). , 27 are stems.

In the figure, control, prefocusing, etc. are performed by the first to fourth lattice electrodes 2 to 5, and the main lens is formed by the fourth lattice electrode 5 as the focusing electrode and the sixth lattice electrode 7 as the anode. Configure.

The shield cup 8 is a so-called shield electrode, which is connected to the anode 7 (sixth electrode) to shield the deflection magnetic field, and has a contact spring or a getter for positioning the electron gun on the inner wall of the neck portion. An electrode component to be fixed is constructed.

In addition to the above-mentioned type, in addition to the above electron gun, it has a cathode, a first grid electrode, a second grid electrode, a third grid electrode, a fourth grid electrode and a shield cup, and a second grid electrode. The present invention can be applied to various types such as a type in which the main lens is constituted by the third grating electrode and the third type.

FIG. 20 is a sectional view for explaining the structure of a color cathode ray tube as one embodiment of the cathode ray tube according to the present invention, in which 31 is a panel portion which constitutes an image screen and 32 is a neck portion which accommodates an electron gun. Reference numeral 33 is a funnel portion connecting the panel portion and the neck portion, 34 is a fluorescent screen formed on the inner surface of the panel portion to form a screen, 35 is a shadow mask, 36 is a mask frame for holding the shadow mask, and 37 is an external magnetic field. , 38 is a suspension spring, 39 is the electron gun according to the present invention, 4
Reference numeral 0 is a deflecting device, 11 is a magnet for correcting centering and purity, and B is an in-line array of three electron beams.

In this figure, in this type of color cathode ray tube, a panel portion 31 having a screen having a phosphor screen 34 formed on the inner surface thereof, a neck portion 32 for accommodating an electron gun 39, and the panel portion and the neck portion are connected. Funnel 33
To form a vacuum envelope. The electron gun 39 housed in the neck portion 32 has the structure described above, and emits three electron beams in an in-line arrangement toward the fluorescent screen 34.

The deflecting device provided on the transition region between the funnel portion and the neck portion of the vacuum envelope deflects the three electron beams emitted from the electron gun 39 in both the horizontal and vertical directions of the fluorescent screen 34 to generate shadows. A color image is formed by being subjected to color selection by the mask 35 and impinging on the phosphor screen 4.

The shadow mask 35 is welded and fixed to the mask frame 36, and the suspension spring 38 fixed to a part of the outer periphery of the mask frame 36 is locked to the panel pin embedded in the inner wall of the panel portion 31. Phosphor screen 3
4 and a predetermined interval.

According to the cathode ray tube of this embodiment, a high resolution image can be obtained over the entire screen.

The present invention is not limited to the above embodiments, but is applicable to other types of electron guns, cathode ray tubes and color cathode ray tubes having this electron gun, and other cathode ray tubes. Needless to say.

[0073]

As described above, according to the present invention,
It is possible to provide an electron gun having a substantially rectangular beam spot on the screen and a rectangular profile in which the rising slope of the bright line when scanning the electron beam is steep and the sharpness of the image is improved.

Further, the deformation and breakage of the opening at the time of assembling the electron gun can be avoided, the generation potential of cold emission can be lowered, and the cathode ray tube can be operated stably, and the reliability is greatly improved. A cathode ray tube with good resolution can be obtained in the entire current region of the electron beam.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a configuration example of an electron gun to which the present invention is applied.

FIG. 2 is a front view of a first grid electrode for explaining a first embodiment of the electron gun according to the present invention, viewed from the second grid electrode side.

FIG. 3 is an enlarged front view of an opening of a first grid electrode as seen from the side of the second grid electrode for explaining the first embodiment of the electron gun according to the present invention.

FIG. 4 is a front view of a second grid electrode for explaining the first embodiment of the electron gun according to the present invention, viewed from the side of the first grid electrode.

FIG. 5 is an explanatory diagram of a raster formed on a screen of a cathode ray tube using the electron gun of the first embodiment of the present invention.

FIG. 6 is a top view of an assembly jig for assembling the electron gun of the first embodiment according to the present invention.

FIG. 7 is a side view of an assembly jig for assembling the electron gun of the first embodiment according to the present invention.

FIG. 8 is a first part of the first embodiment of the electron gun according to the present invention.
It is a principal part sectional view explaining the state which inserted the opening of a grid electrode into the reference rod of an assembly jig.

FIG. 9 is a front view of a first grid electrode for explaining a second embodiment of the electron gun according to the present invention, as viewed from the second grid electrode side.

FIG. 10 is an enlarged front view of an opening of a first grid electrode as seen from the side of the second grid electrode for explaining a second embodiment of the electron gun according to the present invention.

FIG. 11 is a front view of a second grid electrode for explaining a second embodiment of the electron gun according to the present invention, viewed from the first grid electrode side.

FIG. 12 is an enlarged front view of the holes of the second grid electrode for explaining the second embodiment of the electron gun according to the present invention.

FIG. 13 is a front view of a first grid electrode for explaining a third embodiment of the electron gun according to the present invention, viewed from the second grid electrode side.

FIG. 14 is an enlarged front view of an opening of a first lattice electrode viewed from the side of the second lattice electrode for explaining the third embodiment of the electron gun according to the present invention.

FIG. 15 is a cross-sectional view of a main part taken along the line AA of FIG. 13 illustrating a third embodiment of the electron gun according to the present invention.

FIG. 16 is a front view of a second grid electrode for explaining a third embodiment of the electron gun according to the present invention viewed from the first grid electrode side.

FIG. 17 is an enlarged front view of an opening of a second lattice electrode for explaining a third embodiment of the electron gun according to the present invention, seen from the first lattice side;

FIG. 18 is a sectional view taken along the line BB of FIG. 17 for explaining the third embodiment of the electron gun according to the present invention.

FIG. 19 is a side view illustrating an example of an electron gun according to the present invention.

FIG. 20 is a sectional view illustrating the structure of a color cathode ray tube as one example of the cathode ray tube according to the present invention.

FIG. 21 is an explanatory diagram of a raster formed on a screen of a cathode ray tube using an electron gun according to a conventional technique.

[Explanation of symbols]

 1a, 1b, 1c cathode 2 control grid electrode 3 shield grid electrode 4 third grid electrode 5 fourth grid electrode 6 fifth grid electrode 7 sixth grid electrode 7a shield cup 8 (8a, 8b, 8c) open hole 9 square 10a , 10b, 10c, 10d Arcs 11a, 11b, 11c Open holes.

Claims (4)

[Claims] 1. A plurality of cathodes, a control grid electrode, a shield grid electrode, and at least one concentrating electrode are arranged in this order so that electrons generated from each of the plurality of cathodes are common to each other in the form of a plurality of beams. In the electron gun configured to project along, the control grid electrode and the shield grid electrode have a plurality of openings corresponding to the plurality of cathodes, and at least one of the openings is formed in the center of each of the four sides of the rectangle. An electron gun, wherein a part of a part is an arc, and the center of at least two arcs facing each other among the arcs coincides with the center of the rectangle. 2. A plurality of cathodes, a control grid electrode, a shield grid electrode, and at least one concentrating electrode are arranged in this order so that electrons generated from each of the plurality of cathodes are common to each other in the form of a plurality of beams. In the electron gun configured to project along, the control grid electrode and the shield grid electrode have a plurality of openings corresponding to the plurality of cathodes, and the control grid electrode has a rectangular opening shape, and Around the opening, there is a recess whose width in the direction perpendicular to the plane is wider than the width in the direction parallel to the plane including the plurality of beam paths, and the opening of the shielding grid electrode has a rectangular four side. A part of each central part of the arc is an arc, and the centers of at least two arcs facing each other of the arc are in a shape coinciding with the center of the rectangle, and the plurality of beam paths are included around the aperture. Direction perpendicular to the plane An electron gun characterized by having a recess having a width in a direction parallel to the plane that is wider than the width of. 3. A vacuum envelope comprising a panel portion having a phosphor screen, a neck portion for accommodating an electron gun and a funnel portion connecting the panel portion and the neck portion, and a plurality of vacuum envelopes accommodated in the neck portion. In a cathode ray tube that includes at least an electron gun that emits an electron beam in an in-line arrangement, and a deflection device that is provided in a transition region of a funnel portion and a neck portion of the vacuum envelope, the electron gun includes a plurality of cathodes, A control grid electrode, a shield grid electrode, and at least one concentrating electrode are arranged in this order and are configured to project electrons generated from each of the plurality of cathodes in the form of a plurality of beams along a common plane, The control grid electrode and the shield grid electrode have a plurality of openings corresponding to the plurality of cathodes, and at least one of the openings is a part of each central portion of the four sides of the rectangle. An arc, a cathode ray tube, characterized in that opposite at least two arcs of center members out of the arc with a shape that coincides with the center of the rectangle. 4. A vacuum envelope comprising a panel portion having a phosphor screen, a neck portion for accommodating an electron gun, and a funnel portion connecting the panel portion and the neck portion, and a plurality of vacuum envelopes accommodated in the neck portion. In a cathode ray tube including at least an electron gun that emits an electron beam in an in-line arrangement, and a deflection device that is packaged in a transition region of a funnel portion and a neck portion of the vacuum envelope, the electron gun includes a plurality of cathodes, A control grid electrode, a shield grid electrode, and at least one concentrating electrode are arranged in this order and are configured to project electrons generated from each of the plurality of cathodes in the form of a plurality of beams along a common plane, The control grid electrode and the shield grid electrode of the electron gun have a plurality of apertures corresponding to the plurality of cathodes, the control lattice electrode has a rectangular aperture shape, and the aperture is surrounded by the apertures. There is a recess whose width in the direction perpendicular to the plane is wider than the width in the direction parallel to the plane including the plurality of beam paths, and the opening of the shielding grid electrode is at the center of each of the four sides of the rectangle. Part of the arc is a shape in which the centers of at least two opposing arcs of the arc match the center of the rectangle, and are perpendicular to the plane including the plurality of beam paths around the aperture. A cathode ray tube having a recess whose width in a direction parallel to the plane is wider than width in a different direction.