JPH04282538A - Color cathode tube - Google Patents

Abstract

PURPOSE:To substantially improve resolution. CONSTITUTION:Bottomed recessed hole parts 34, 35 are formed in a facing part between a tubular focusing electrode 29 and a tubular final acceleration electrode 30 forming a main lens of an electron gun arranged in a single row passing on the same plane to emit three electron beams, the first circular arc- shaped opening part is formed in a bottom surface part in the outside of a pair of side beam passing holes in the bottomed recessed hole part of at least one of these focussing electrode and final acceleration electrode, the second circular arc-shaped opening part is formed in a side surface of at least the one above-mentioned electrode so as to surround this first opening part, and an auxiliary electrode, to which voltage higher than the voltage applied to the focusing electrode and lower than the voltage applied to the final acceleration electrode is applied, is arranged in the vicinity of this second opening part.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and more particularly to an in-line color cathode ray tube having an electron gun that improves the resolution on a phosphor screen.

0002

2. Description of the Related Art Generally, in a color cathode ray tube, a phosphor screen made of three color phosphor layers is formed on the inner surface of a panel of an envelope, facing a shadow mask in which a large number of electron beam passage holes are formed. The three electron beams emitted from the electron gun are deflected by a magnetic field generated by a deflection yoke attached to the outside of the envelope, and the phosphor screen is horizontally and vertically scanned through the shadow mask. It is formed into a structure that displays a color image on top.

Among such color cathode ray tubes, an in-line color cathode ray tube in which the electron gun is an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane is used. Currently, it is the mainstream color cathode ray tube.

By the way, the resolution of a color cathode ray tube generally depends on the size and shape of the beam spot on the phosphor screen. Therefore, in order to improve the resolution, it is necessary to make the beam spot as small as possible and to have a shape with little distortion. Furthermore, the convergence characteristics of the three electron beams is also an important factor.

In order to reduce the beam spot on the phosphor screen, the aperture of the electrode that forms the main lens of the electron gun that ultimately focuses the electron beam on the phosphor screen is increased to eliminate spherical aberration. It is effective to make it smaller. For this purpose, it is necessary to increase the mutual spacing between the three electron beams. However, increasing the mutual spacing between the electron beams deteriorates the convergence characteristics of the three electron beams, and the diameter of the electrode constituting the main lens is limited by the inner diameter of the neck of the envelope in which the electron gun is disposed.

Conventionally, as a means of reducing the spherical aberration of the main lens without increasing the mutual spacing between the electron beams or the inner diameter of the neck, an electron gun has been developed in which the main lens is a large-diameter lens that acts in common on three electron beams. There is.

FIG. 6 shows an example of such an electron gun. This electron gun includes three cathodes 1B, 1G, and 1R arranged in a row, three heaters (not shown) that heat these cathodes 1B, 1G, and 1R, and the front surfaces of the cathodes 1B, 1G, and 1R (phosphor A control electrode 2, an acceleration electrode 3, a focusing electrode 4, a final acceleration electrode 5, and a convergence electrode 6 attached to this final acceleration electrode 5 are sequentially arranged on the screen side).
Consisting of Each electrode 2 to 6 of this electron gun has three circular electron beam passing holes arranged in a row corresponding to the three cathodes 1B, 1G, and 1R in the same direction as the arrangement direction of the cathodes 1B, 1G, and 1R. It is formed.

Cathodes 1B, 1G, 1R of this electron gun,
The voltages shown in Table 1 are applied to the control electrode 2, acceleration electrode 3, focusing electrode 4, and final acceleration electrode 5.

[0009]

By applying this voltage, electron emission from the cathodes 1B, 1G, 1R is controlled by the cathodes 1B, 1G, 1R, the control electrode 2, and the acceleration electrode 3,
3 which focuses the electrons emitted from the cathodes 1B, 1G, and 1R to form three electron beams 7B, 7G, and 7R.
A pole part is formed, and three electron beams 7B, 7G, 7R are generated from this three pole part by the next focusing electrode 4 and the final acceleration electrode 5.
A main lens is formed that accelerates and focuses the three electron beams 7B, 7G, and 7R toward the phosphor screen.
, 7R are focused onto a phosphor screen.

In particular, the focusing electrode 4 and the final accelerating electrode 5 of this electron gun have an elliptical bottomed concave hole whose major axis is in the direction in which the cathodes are arranged, that is, in the direction in which the three electron beams are arranged, in their respective opposing parts. 9, 10 are formed, and the bottomed concave holes 9, 10 are formed.
Three cylindrical protrusions are formed on the bottom of the screen, surrounded by three cylindrical protrusions that protrude in the direction of the opposing electrodes, that is, the focus electrode 4 protrudes in the direction of the final acceleration electrode 5, and the final acceleration electrode 5 protrudes in the direction of the focus electrode 4. circular electron beam passage hole 11B
, 11G , 11R and 12B , 12G , 12
R is formed, and three circular electron beam passing holes 11 are surrounded by the bottomed concave holes 9 and 10 and the cylindrical protrusion.
B , 11G , 11R and 12B , 12G ,
12R, the main lens is connected to 3 electron beams 7B, 7G.
, 7R, and a lens for each of the three electron beams 7B, 7G, and 7R.

However, when the bottomed concave holes 9 and 10 are formed in the shape of an ellipse whose major diameter is in the direction in which the three electron beams are arranged in the opposing parts of the focusing electrode 4 and the final accelerating electrode 5 as described above, the main Since the lens is a non-rotationally symmetrical lens whose major axis is in the direction in which the three electron beams are arranged, the focusing power in the major axis direction and in the minor axis direction perpendicular to this is more focused on the pair of side beams 7B and 7R than on the center beam 7G. has a strong effect on As a result, a center beam 7G and a pair of side beams 7B,
There is a problem that the focusing points of 7R are different, and the focusing of the three electron beams 7B, 7G, and 7R on the phosphor screen becomes uneven, and the beam spots 13B, 13G, and 13R are not minimized, resulting in deterioration of resolution. .

[0013]

[Problems to be Solved by the Invention] As mentioned above, in order to improve the resolution of conventional in-line color cathode ray tubes, three electron beams are placed at the opposing portions of the focusing electrode and the final accelerating electrode, which form the main lens of the electron gun. An oval bottomed concave hole having a major axis in the arrangement direction is formed, and the bottom surface of the bottomed concave hole is surrounded by three cylindrical protrusions each protruding toward the counter electrode. There is one in which three circular electron beam passage holes are formed, and the main lens is a large-diameter lens consisting of a lens common to the three electron beams and a lens for each of the three electron beams.

However, when the main lens is formed as described above, the main lens becomes a non-rotationally symmetrical lens whose major axis is in the direction in which the three electron beams are arranged. The focusing force acts more strongly on the pair of side beams than on the center beam, and as a result, the center beam and the pair of side beams have different focal points, and the three electron beams become unevenly focused on the phosphor screen, causing the beam There is a problem in that the spot is distorted in a horizontal direction and is not minimized, resulting in deterioration of resolution.

The present invention was made to solve the above problems, and is a color cathode ray having an electron gun that emits three electron beams arranged in a row, consisting of a center beam and a pair of side beams passing on the same plane. In a tube, the purpose is to improve resolution by making the beam spot on a phosphor screen small and free of distortion.

[Configuration of the invention]

[0017]

[Means for Solving the Problem] The present invention has an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams that pass on the same plane, and the three electron beams emitted from this electron gun are the final Bottomed concave holes are formed in the opposing parts of the cylindrical focusing electrode and the cylindrical final acceleration electrode, which form the main lens that focuses on the phosphor screen. In a color cathode ray tube formed with three electron beam passing holes arranged in a row, each consisting of a center beam passing hole through which the three electron beams pass separately and a pair of side beam passing holes, a focusing electrode forming the main lens is provided. and of the final accelerating electrode,
An arc-shaped first opening is formed in the bottom surface outside the pair of side beam passage holes in the bottomed concave hole of at least one of the electrodes, and the first opening of the at least one of the electrodes is formed so as to surround the first opening. A second arc-shaped opening is formed on the side surface, a voltage higher than the voltage applied to the focusing electrode is applied to the focusing electrode near the second opening, and a voltage higher than the voltage applied to the focusing electrode is applied to the final acceleration electrode. An auxiliary electrode was placed to which a voltage lower than the voltage applied to the electrode was applied.

[0018]

[Operation] As described above, an arc-shaped first electrode is formed on the bottom surface outside the pair of side beam passing holes in the bottomed concave hole of at least one of the focusing electrode and the final acceleration electrode forming the main lens. an arc-shaped second opening is formed in the side surface of the at least one electrode so as to surround the first opening, and the focusing electrode is located near the second opening. When an auxiliary electrode is arranged to which a voltage higher than that applied to the final accelerating electrode is applied and a voltage lower than the voltage applied to the final accelerating electrode is applied, the voltage of the pair of at least one of the electrodes is A pair of side beams that pass through the main lens, which is a non-rotationally symmetrical lens whose major axis is in the direction in which the three electron beams are arranged, which can increase the penetration of potential into the inside of the side beam passage hole and reduce the curvature of the equipotential surface. By weakening the focusing power in the major axis and minor axis directions of the beam, it is possible to create a large aperture lens with low magnification and aberration that uniformly focuses the center beam and a pair of side beams. The beam spot can be made small without distortion.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings.

FIG. 3 shows an in-line color cathode ray tube that is one embodiment of the present invention. This color cathode ray tube has panel 2
0 and a funnel 21 integrally joined to this panel 20, and on the inner surface of the panel 20 is a phosphor screen 22 consisting of a striped three-color phosphor layer that emits blue, green, and red light. is formed, and a shadow mask 23 having a large number of electron beam passage holes formed therein is arranged opposite to this phosphor screen 22. Further, an electron gun 26 is disposed in the neck 24 of the funnel 21 and emits three electron beams 25B, 25G, 25R arranged in a row, consisting of a center beam 25G and a pair of side beams 25B, 25R that pass on the same horizontal plane. There is. The three electron beams 25B, 25G, and 25R emitted from the electron gun 26 are deflected by a magnetic field generated by a deflection yoke 27 mounted on the outside of the funnel 21 to scan the phosphor screen 22 horizontally and vertically. By this, this phosphor screen 22
It is formed into a structure that displays a color image on top.

The electron gun 26 has a BPF (Bipote
ntial Focus) type electron gun, and as shown in Figure 1, three cathodes 1 are arranged in a row in the horizontal direction.
B, 1G, 1R, three heaters (not shown) that heat these cathodes 1B, 1G, 1R, the cathode 1B,
A control electrode 2, an acceleration electrode 3, a focusing electrode 29, a final acceleration electrode 30, a convergence electrode 6 attached to this final acceleration electrode 30, and a first , second correction electrodes 31 and 32.

The control electrode 2 and the accelerating electrode 3 are plate-shaped electrodes of an integral structure in the shape of an ellipse whose major diameter is in the direction in which the cathodes 1B, 1G, and 1R are arranged (the direction in which the three electron beams are arranged). On the surface, there are three cathodes 1B, 1G,
Three circular electron beam passing holes are formed in a row in the horizontal direction corresponding to 1R. The focusing electrode 29 and the final accelerating electrode 30 are cylindrical electrodes having an elongated, integral structure whose major axis is in the direction in which the cathodes 1B, 1G, and 1R are arranged. ,
That is, on the surface of the focusing electrode 29 facing the accelerating electrode 3 and the surface of the final accelerating electrode 30 facing the convergence electrode 6, three circular electron beams are formed in the horizontal direction corresponding to the three cathodes 1B, 1G, 1R. The passage holes are arranged in a row. Furthermore, the convergence electrode 6 is also connected to the cathode 1.
It consists of an integrated cylindrical electrode with an oval shape whose major axis is in the direction in which cathodes B, 1G, and 1R are arranged, and three electrodes are arranged horizontally on the bottom of the electrode, corresponding to the three cathodes 1B, 1G, and 1R. A row of circular electron beam passing holes are formed.

Further, the focusing electrode 29 and the final accelerating electrode 30 of the electron gun 26 include a surface of the focusing electrode 29 facing the final accelerating electrode 30 and a surface of the focusing electrode 29 of the final accelerating electrode 30.
9, three cathodes 1B, 1G,
An elliptical bottomed concave hole portion 34 whose major axis is in the 1R arrangement direction.
, 35 are formed. And the bottomed concave hole part 34,
At the bottom of the counter electrode 35, the bottomed concave hole 34 of the focusing electrode 29 has three cylindrical protrusions protruding toward the final acceleration electrode 30, and the bottomed concave hole of the final acceleration electrode 30 35, 3 protrudes toward the focusing electrode 29.
Cylindrical protrusions are formed in a line in the arrangement direction of the three cathodes 1B, 1G, and 1R, and inside each of the cylindrical protrusions are center beam passage holes 36G, 37G and a pair of side beam passage holes 36B. ,36R ,37B
, 37R three circular electron beam passing holes 36
B, 36G, 36R and 37B, 37G,
37R is formed.

Further, the bottoms of the bottomed concave holes 34 and 35 of the focusing electrode 29 and the final accelerating electrode 30 are shown in FIG.
As shown, a pair of arcuate first openings 38 and 39 are provided on the outside of the pair of side beam passage holes 36B, 36R, 37B and 37R, respectively, with a cylindrical protrusion surrounding them interposed therebetween. . Furthermore, on the side surfaces of the focusing electrode 29 and the final acceleration electrode 30, the first
A pair of arc-shaped second openings 40 and 41 are provided to surround the openings 38 and 39.

The second opening 4 of the focusing electrode 29
The first correction electrode 31 closes the second opening 40 in the vicinity of 0, and the second opening 41 of the final acceleration electrode 30 closes the second opening 40.
A second correction electrode 32 is arranged near the second opening 41 so as to close each of the second openings 41, the first correction electrode 31 is connected to the final acceleration electrode 30, and the second correction electrode 32 is connected to the focusing electrode 2.
9 is connected.

Cathodes 1B, 1G, 1 of this electron gun 26
During operation, the voltages shown in Table 1 are applied to the control electrode 2, the acceleration electrode 3, the focusing electrode 29, and the final acceleration electrode 30, so that the electrodes are arranged near the second opening 40 of the focusing electrode 29. The final acceleration electrode 30 is attached to the first correction electrode 31
A voltage of about 25 kV is applied to the second opening 41 of the final accelerating electrode 30 .
The correction electrode 32 has a voltage of approximately 7.5 cm applied to the focusing electrode 29.
A voltage of kV is applied.

[0027] Thereby, the cathodes 1B, 1G, 1R,
By the control electrode 2 and the acceleration electrode 3, the cathodes 1B, 1
A triode part is formed that controls electron emission from G and 1R and focuses the emitted electrons to form electron beams 15B, 15G, and 15R, and is connected between the next focusing electrode 29 and the final accelerating electrode 30. A main lens is formed which ultimately accelerates and focuses the electron beams 25B, 25G, 25R extracted from the triode portion toward the phosphor screen 22.

By the way, when the electron gun 16 is constructed as described above, the potential distribution on the focusing electrode 29 side of the main lens becomes an equipotential surface with a certain curvature due to the penetration of the high potential of the final accelerating electrode 30, and Due to the penetration of the high potential of the first correction electrode 31 which has the same potential as the final acceleration electrode 30, it penetrates deeply into the inside of the focusing electrode 29. Further, the potential distribution on the final accelerating electrode 30 side also penetrates deeply into the inside of the final accelerating electrode 30, similar to the potential distribution on the focusing electrode 29 side. As a result, as shown in FIG. 4, the potential distribution 43a of the main lens of the electron gun 26
is the potential distribution 43 of the main lens of the conventional electron gun shown in FIG.
b compared to focusing electrode 29 and final acceleration electrode 30
It becomes an equipotential surface with large inward potential penetration and small curvature. As a result, a large diameter lens is formed in the main lens with small magnification and aberration, and compared to the horizontally elongated beam spots 13B, 13G, 13R of the conventional electron gun shown in FIG. 6, the phosphor screen as shown in FIG. The upper beam spots 44B, 44G, and 44R can all be made perfect circles without distortion and can be made small, and the resolution can be greatly improved.

In the above embodiment, arc-shaped first and second openings were provided in both the focusing electrode and the final acceleration electrode forming the main lens, and the auxiliary electrode was placed in the second opening. The same effect can be obtained even if the first and second openings and the auxiliary electrode are provided only on one of the focusing electrode and the final acceleration electrode forming the main lens.

Furthermore, in the above embodiment, the auxiliary electrode placed in the second opening of the focusing electrode is connected to the final acceleration electrode, and the auxiliary electrode placed in the second opening of the final acceleration electrode is connected to the focusing electrode. , a voltage higher than that of the focusing electrode was applied to the auxiliary electrode on the focusing electrode side, and a voltage lower than that of the final accelerating electrode was applied to the auxiliary electrode on the final accelerating electrode side, but these auxiliary electrodes A predetermined voltage may be applied to each of the electrodes without being connected to the final acceleration electrode or the focusing electrode.

Furthermore, in the above embodiment, a BPF type electron gun was explained, but the present invention is applicable not only to a BPF type electron gun but also to a UPF (Unipotential Foam).
Cus) type electron gun, QPF (Quodrapotent)
The present invention can also be applied to color cathode ray tubes having other electron guns such as ial focus type electron guns.

[0032]

Effect of the invention: A cylindrical focusing electrode and a cylindrical final accelerating electrode, which form the main lens of an electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane, are opposed to each other. Three electron beam passing holes arranged in a row, each consisting of a center beam passing hole through which the three electron beams pass separately and a pair of side beam passing holes, are formed in the bottom of the bottomed concave hole formed in the part. , an arcuate first opening is formed in the bottom surface outside the pair of side beam passage holes in the bottomed concave hole of at least one of the focusing electrode and the final acceleration electrode, and the first opening A second arc-shaped opening is formed in the side surface of at least one of the electrodes so as to surround the focusing electrode, and a voltage higher than the voltage applied to the focusing electrode is applied near the second opening. When an auxiliary electrode is arranged to which a voltage lower than the voltage applied to the final acceleration electrode is applied, the potential penetrates into the inside of the pair of side beam passage holes of the at least one electrode. can be made larger and the curvature of the equipotential surface smaller,
3. The focusing power of the pair of side beams in the major axis direction and minor axis direction is weakened to uniformly focus the center beam and the pair of side beams, which pass through the main lens, which is a non-rotationally symmetrical lens whose major axis is in the direction in which the electron beams are arranged. It can be a large aperture lens with low magnification and aberration. the result,
It is possible to make the beam spot on the phosphor screen a perfect circle without distortion and to make it small, and the resolution can be greatly improved.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional plan view showing the structure of an electron gun for a color cathode ray tube according to an embodiment of the present invention.
b) is a side view also shown in section.

FIG. 2(a) is a perspective view showing the structure of a focusing electrode and a final accelerating electrode of the electron gun, and FIG. 2(b) is a plan view showing the structure of the focusing electrode and final accelerating electrode.

FIG. 3 is a diagram showing the configuration of a color cathode ray tube that is an embodiment of the present invention.

FIG. 4 is a diagram for explaining the potential distribution of the main lens of the electron gun.

FIG. 5 is a diagram showing the potential distribution of the main lens of the conventional electron gun in comparison with the potential distribution of the main lens of the electron gun.

FIG. 6(a) is a plan view showing the structure of a conventional color cathode ray tube electron gun in cross section, and FIG. 6(b) is a side view showing the same in cross section.

[Explanation of symbols]

1B, 1G, 1R... Cathode 2... Control electrode 3... Accelerating electrode 22... Phosphor screen 25B, 25R... Pair of side beams 25G... Center beam 26... Electron gun 29... Focusing electrode 30... Final accelerating electrode 31... Auxiliary electrode 32 ... Auxiliary electrode 34 ... Bottomed recessed hole section 35 ... Bottomed recessed hole section 36B, 36R ... Pair of side beam passage holes 36G
...Center beam passing holes 37B, 37R...Pair of side beam passing holes 37G
...Center beam passage hole 38...First opening 39...First opening 40...Second opening 41...Second opening

Claims (1)

[Claims] Claim 1: An electron gun that emits three electron beams arranged in a row consisting of a center beam and a pair of side beams passing on the same plane, and the three electron beams emitted from this electron gun.
Bottomed concave holes are formed in opposing parts of the cylindrical focusing electrode and the cylindrical final acceleration electrode that form the main lens that ultimately focuses the electron beam onto the phosphor screen, and these bottomed concave holes In a color cathode ray tube, three electron beam passing holes are formed in a row, each consisting of a center beam passing hole through which the three electron beams pass separately and a pair of side beam passing holes, on the bottom surface of the tube. An arcuate first opening is formed in the bottom surface of at least one of the focusing electrode and the final acceleration electrode outside the pair of side beam passing holes in the bottomed concave hole of the first electrode.
An arc-shaped second opening is formed in the side surface of the at least one electrode so as to surround the opening, and a voltage higher than the voltage applied to the focusing electrode is applied to the focusing electrode near the second opening. is applied to the final accelerating electrode, and an auxiliary electrode is arranged to which a voltage lower than the voltage applied to the final accelerating electrode is applied.