JPH06103917A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To improve the image quality of a color cathode-ray tube using a deflecting device which has no coma correcting unit. CONSTITUTION:At least in one electrode of the first grid electrode 1, the second grid electrode 2, and the third grid electrode 3, to form an electron gun, the form or the area of the center beam passing hole 1-1 is made different from the side beam passing holes 1-2 and 1-3. As a result, the function of the deflection magnetic field when the side beams scan the periphery of the image screen is made different from the function of the deflection magnetic field to the center beam, and the spots of the center beam and the side beams are made almost in the same form. Consequently, an image of a high resolution is displayed along the whole area of the image screen.

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, and in particular, a panel portion having an inner surface coated with a fluorescent surface composed of a phosphor layer which emits light by electron beam bombardment, and a funnel on the panel portion. A neck portion connected through the electron gun, an electron gun attached to the neck portion to emit the electron beam, and a deflection device attached to the outer wall of the funnel portion to scan the electron beam on the phosphor screen. Color cathode ray tube.

[0002]

2. Description of the Related Art In general, a color cathode ray tube of this type displays an image on a screen composed of a phosphor layer by electromagnetically deflecting and scanning an electron beam emitted by being modulated by an image signal from an electron gun. Is. FIG. 6 is a vertical cross-sectional view for explaining the structure of a color cathode ray tube according to the related art.
Is a panel portion, 11 is a phosphor layer, 12 is a funnel portion, 1
3 is a neck portion, 14 is a deflecting device, 15 is an electron gun, 16 is a correction magnet group, 17 is a shadow mask, 18 is a magnetic shield, 19 is a deflection magnetic field, and 20 is an electron beam.

In the figure, an image signal is given to the electron gun 15, and the electron beam modulated by the image signal is formed on the inner surface of the panel portion 10 by passing through the magnetic field formed by the deflecting device 14. Scanning is performed on a screen (screen) formed of the phosphor layer 11. The correction magnet group 16 corrects convergence and color purity, and the magnetic shield 18 shields an external magnetic field such as the earth magnetism to prevent mislanding of the electron beam.

The in-line self-convergence method, which is the standard for the combination of the cathode ray tube and the deflection device, is a method that does not require a convergence correction circuit, and is an excellent method from the viewpoint of resource saving and energy saving.
Since the horizontal magnetic field of the deflecting device 14 is a pincushion distribution and the vertical magnetic field is a barrel distribution to achieve self-convergence, the electron beam spot shape is distorted at the peripheral portion of the screen.

FIG. 7 is a schematic view for explaining the electron beam spot distortion on the screen, and is a view of the panel portion of the color cathode ray tube as seen from the front. In the figure, 21,2
2 and 23 are the shapes of the red, green and blue electron beam spots in the center of the screen, 22 ', 22', 23 'and 2
Reference numerals 2 ", 22", and 23 "indicate the shapes of the red, green, and blue electron beam spots in the peripheral portion of the screen. Needless to say, the red electron beam and the blue electron beam are side electrons forming the electron gun 15. An electron beam emitted from a gun (side gun), and a green electron beam is an electron beam emitted from a center electron gun (center gun).

As shown in the drawing, red,
The shape distortion of the green and blue electron beam spots is extremely small, but the shape distortion of the red and blue electron beam spots from the side gun is much smaller in the peripheral area of the screen than the distortion of the green electron beam from the center gun. Is remarkable. That is, the focus characteristics deteriorate in the peripheral portion of the screen. The shape distortion (deflection distortion) peculiar to the inline self-convergence method can be improved by attaching a coma aberration correction unit that generates a distortion correction magnetic field to the deflection device. However, attaching a coma-aberration correction unit to the deflector increases the cost of the deflector. Therefore, in a color cathode-ray tube aiming at a low price, the coma-aberration correction unit may be omitted to sacrifice the focus characteristic. .

As means for improving the focus characteristics of such a color cathode ray tube, Japanese Patent Laid-Open No. 54-133307 has been proposed.
The technique disclosed in Japanese Patent Publication is known. FIG. 8 is a configuration diagram of an electron gun for improving focus characteristics disclosed in the above-mentioned prior art, in which 24 is a first grid electrode, 25 is a second grid electrode, 26 is a third grid electrode, and 27 is a fourth grid. Electrode, 28 is cup electrode, 29 is bead glass, 30
Is a stem and K is a cathode.

This electron gun has a cathode K, a first grid electrode 24, a second grid electrode 25, and a third grid electrode 2.
6, the fourth grid electrode 27 is fixed to the bead glass 32 with a predetermined electrode interval, and the electron beam emitted from the cathode K is directed to the first grid electrode 24, the second grid electrode 25, the third grid electrode 26, and the third grid electrode 26. 4 grid electrode 2
It is accelerated and focused at 7 and emitted in the screen direction.

The first grid electrode 24, the second grid electrode 25, and the third grid electrode 26 form a prefocus portion, and the focus characteristics are improved by the electron beam passage hole shape of the grid electrode forming the prefocus portion. It is what makes me. FIG. 9 is a plan view of the main part of the electron gun shown in FIG. 8, showing in enlarged form the shape of the electron beam passage hole formed in the first grid electrode 24 constituting the prefocus portion of the electron gun. 33R, 33G,
33B is a rectangular red electron beam (side beam)
Through hole, green electron beam (center beam) through hole, blue electron beam (side beam) through hole, 33Ra33Ga,
33Ba shows the corner of each beam passage hole. The second grid electrode 25 and the third grid electrode 26 may be provided with the same electron beam passage hole shape as described above.

As shown in the figure, in the above-mentioned conventional electron gun, the first grid electrode 24, the second grid electrode 25, and the third grid electrode 2 forming the prefocus portion are formed.
The shape of the electron beam passage hole formed in any of the electrodes 6 is rectangular, and the xx direction passing through the corner 33a is the vertical magnetic field direction of the deflection magnetic field, and the yy direction orthogonal thereto is the horizontal magnetic field. It is arranged to match the direction. Note that s is the distance between the electron beam passage holes.

With such a shape of the electron beam passage hole, the influence of the deflecting magnetic field on the center beam and the side beam can be made different to alleviate the shape distortion of the electron beam spot in the peripheral portion of the screen to improve the focus characteristic. .

[0012]

However, in the above-mentioned conventional technique, it is formed on any one of the first grid electrode 24, the second grid electrode 25, and the third grid electrode 26 which constitute the prefocus portion. By making the shape of the electron beam passage hole as shown in FIG. 9, the absolute amount of shape distortion at the peripheral portion of the screen of the side beam spot is reduced, but the difference in shape between the center beam spot and the side beam spot is reduced. However, there is a problem that the image quality of an actually observed image still seems to be deteriorated.

It is an object of the present invention to provide a color cathode ray tube which solves the above-mentioned problems of the prior art and improves the image quality when a deflecting device having no coma correction unit is used.

[0014]

In order to achieve the above object, the present invention provides a panel portion having an inner surface coated with a phosphor layer which emits light by electron beam bombardment, and a funnel portion provided on the panel portion. Color cathode ray tube including at least a neck portion connected to each other, an electron gun that is housed in the neck portion to emit the electron beam, and a deflection device that is mounted on the outer wall of the funnel portion and scans the electron beam on the phosphor layer. In at least one of the first grid electrode 1, the second grid electrode 2, and the third grid electrode 3 which form the prefocus system of the electron gun, the shape of the center beam passage hole 1-1 and the side beam passage hole 1 It is characterized in that the shapes of −2 and 1-3 are different.

Further, according to the present invention, a panel portion having an inner surface coated with a phosphor layer which emits light by electron beam bombardment, a neck portion connected to the panel portion through a funnel portion, and a neck portion are housed in the neck portion. A color cathode ray tube including at least an electron gun that emits the electron beam and a deflection device that is mounted on the outer wall of the funnel portion to scan the phosphor layer with the electron beam, and configure a prefocus system of the electron gun. The shape of the center beam passage hole 1-1 of at least one of the first grid electrode 1, the second grid electrode 2, and the third grid electrode 3 is non-circular, and the side beam passage hole 1
-2,1-3 are formed into the center beam passage hole 1-1.
Is rotated according to the characteristics of the deflection device.

The present invention further comprises a panel section having an inner surface coated with a phosphor layer which emits light by electron beam bombardment.
With the neck part connected to the panel part through the funnel part,
A color cathode ray tube comprising at least an electron gun which is housed in a neck portion and emits the electron beam, and a deflecting device which is mounted on an outer wall of a funnel portion and scans the electron beam on a phosphor layer. The area of the center beam passage hole 1-1 and the side beam passage holes 1-2 and 1-3 of at least one of the first grid electrode 1, the second grid electrode 2, and the third grid electrode 3 which form the focus system.
It is characterized in that the areas of are different.

[0017]

With the color cathode ray tube using the electron gun having the above-described structure of the present invention, the action of the deflection magnetic field when the side beam scans the peripheral portion of the screen is different from the action of the deflection magnetic field with respect to the center beam. Therefore, the spots of the center beam and the side beams in the peripheral portion of the screen have almost the same shape.

As a result, a high resolution image is displayed over the entire screen.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a side view (a) for explaining the overall structure of an electron gun used in one embodiment of a color cathode ray tube according to the present invention and a front view (b) for explaining the structure of the main electrodes thereof. 1, 1 is a first grid electrode, 2 is a second grid electrode, 3 is a third grid electrode, 4 is a fourth grid electrode, 5 is a fifth grid electrode, 6 is a sixth grid electrode, 7 is a cup electrode, 8 Is a stem, 9 is a bead glass, and K is a cathode. Also, in (b), 1 is the first
Grid electrodes, 1-1 is a center beam passage hole, 1-
2, 1 to 3 are side beam passage holes, and s is an arrangement interval between electron beams.

In FIG. 1A, the first grid electrode 1
And the second grid electrode 2 and the third grid electrode 3 constitute a prefocus lens system, and the electron beam emitted from the cathode K passes through the prefocus lens system and passes through the third grid electrode 3, the fourth grid electrode 4, Fifth grid electrode 5
Then, it is focused and accelerated by the main lens system composed of the sixth grid electrode 6 and advances to the deflection area of the deflector.

FIG. 2B is a front view of the first grid electrode in FIG. 1A, in which the center beam hole 1-1 and the side beam holes 1-2 and 1-3 are in-line with a constant spacing s. Are arranged in. The center beam hole 1-1
Is a green electron beam, and side beam holes 1-2 and 1-3 pass a red electron beam and a blue electron beam, respectively. And
The center beam hole 1-1 and the side beam holes 1-2,
1-3, the aperture shape or aperture area is different, which causes the action of the deflection magnetic field to be different from that of the center beam when the side beam scans the peripheral portion of the screen, so that the center beam and the side beam also in the peripheral portion of the screen The spot shapes are substantially the same.

FIG. 2 is an enlarged schematic view of an essential portion for explaining the details of the electron beam passage hole portion of the first grid electrode shown in FIG. 1 (b). The center beam passage hole 1-1 has a diameter L ₂
Round holes, the side beam through holes 1-2 and 1-3 x-x direction diameter y-y direction size in square holes of L ₁ in L _1, the center beam passage hole 1-1 and the side beam through holes of the 1-2,1-
The opening areas of 3 are the same.

That is, the diameter L _{1 of} the electron beam passage hole in the xx direction, which directly affects the shape of the beam spot on the screen.
And the y-y direction diameter L ₁ is the center beam passage hole 1-1.
Made with respect to the diameter L ₂ and _{L 2 ≦ L 1 (πL 2} 2/4 ≦
L ₁ ² ). With this configuration, the spot shape of the side beam on the screen can be changed, and an image display with good resolution can be obtained over the entire screen.

FIG. 3 shows a second embodiment of the color cathode ray tube according to the present invention.
FIG. 3 is an enlarged schematic view of an essential part similar to FIG. 2 for explaining the embodiment, and the same reference numerals as those in FIG. 2 correspond to the same parts. In the figure, both the center beam passage hole 1-1 and the side beam passage holes 1-2 and _1-3 are square holes having a side length of L ₃ .
The center beam passage hole 1-1 has its sides in the x-x direction and y.
The arrangement coincides with the -y direction.

On the other hand, the side beam passage holes 1-2,
1-3 is a shape in which the center beam passage hole 1-1 is rotated by an angle θ ₁ . With this configuration, the spot shape of the side beam on the screen can be changed, and an image display with good resolution can be obtained over the entire screen. FIG. 4 is an enlarged schematic view of an essential part similar to the above-described embodiment for explaining the third embodiment of the color cathode ray tube according to the present invention, and the same reference numerals correspond to the same parts.

In the figure, the center beam passage hole 1-
1, the side beam passage holes 1-2 and 1-3 are both round holes, the center beam passage hole 1-1 has a diameter of L ₄ , and the side beam passage holes 1-2 and 1-3 have a diameter of L ₅ . , L ₄ ＞
It is L ₅ . Also with this configuration, similarly to the above-described embodiment, the spot shape of the side beam on the screen can be changed, and an image display with good resolution can be obtained over the entire screen.

FIG. 5 shows a fourth embodiment of the color cathode ray tube according to the present invention.
FIG. 7 is an enlarged schematic view of an essential part similar to the above-described embodiment for explaining an embodiment, and the same reference numerals correspond to the same parts. In the figure, the center beam passage hole 1-1 is a rhombic opening with one side L ₆ , and the side beam passage holes 1-2 and 1-3 have one side L _7.
Of the center beam passage hole 1-1> (opening area of the side beam passage holes 1-2, 1-3).

With this configuration, as in the above embodiment,
The spot shape of the side beam on the screen can be changed, and an image display with good resolution can be obtained over the entire screen. In each of the above-described embodiments, the shape and area of the electron beam passage hole provided in the first grid electrode as the resolution improving means of the color cathode ray tube are different between the center beam and the side beam.

However, the present invention is not limited to this, and the second grid electrode or the third grid electrode, or any two of the first grid electrode, the second grid electrode and the third grid electrode is the same as above. It is also possible to add the above means in combination. Further, regarding the non-circular electron beam passage hole, the diameter in the xx direction, the diameter in the yy direction,
The optimum focus characteristic can be obtained by appropriately selecting the rotation angle and the area of the side beam passage hole according to the characteristic of the deflecting device.

[0030]

As described above, according to the present invention,
At least one electron beam passage hole of the first grid electrode, the second grid electrode, and the third grid electrode forming the electron gun is provided with a configuration in which the center beam passage hole and the side beam passage hole have different opening shapes or opening areas. As a result, the spot shape of the side beam in the peripheral portion of the screen can be made substantially the same as the spot shape of the center beam.

This makes it possible to provide a color cathode ray tube having excellent resolution over the entire screen.

[Brief description of drawings]

FIG. 1 is a side view (a) for explaining the overall structure of an electron gun used in an embodiment of a color cathode ray tube according to the present invention and a front view (b) for explaining the structure of main electrodes thereof.

FIG. 2 is an enlarged schematic view of an essential part for explaining details of an electron beam passage hole portion of a first grid electrode of an electron gun used in one embodiment of a color cathode ray tube according to the present invention.

FIG. 3 is an enlarged schematic view of an essential part similar to FIG. 2 for explaining a second embodiment of the color cathode ray tube according to the present invention.

FIG. 4 is an enlarged schematic view of an essential part similar to the above-mentioned embodiment for explaining a third embodiment of the color cathode ray tube according to the present invention.

FIG. 5 is an enlarged schematic view of an essential part similar to the above-described embodiment for explaining a fourth embodiment of the color cathode ray tube according to the present invention.

FIG. 6 is a vertical sectional view for explaining a structure of a color cathode ray tube according to a conventional technique.

FIG. 7 is a schematic diagram illustrating electron beam spot distortion on a screen of a color cathode ray tube according to a conventional technique.

FIG. 8 is a configuration diagram of an electron gun for improving focus characteristics disclosed in the related art.

9 is a plan view of relevant parts of the conventional electron gun of FIG.

[Explanation of symbols]

 1 1st grid electrode 2 2nd grid electrode 3 3rd grid electrode 4 4th grid electrode 5 5th grid electrode 6 6th grid electrode 7 cup electrode 8 stem 9 bead glass K cathode 1-1 center beam passage hole 1-2 , 1-3 Side beam passage holes s Array spacing between electron beams

Claims (3)

[Claims] 1. A panel portion having an inner surface coated with a phosphor layer that emits light by electron beam bombardment, a neck portion connected to the panel portion through a funnel portion, and the electron beam accommodated in the neck portion. In a color cathode ray tube comprising at least an electron gun for emitting light and a deflecting device mounted on an outer wall of a funnel portion for scanning an electron beam on a phosphor layer, a first grid electrode constituting a prefocus system of the electron gun. A color cathode ray tube characterized in that at least one of the second grid electrode and the third grid electrode has a center beam passage hole and a side beam passage hole having different shapes. 2. A panel portion having an inner surface coated with a phosphor layer that emits light by electron beam bombardment, a neck portion connected to the panel portion through a funnel portion, and the electron beam accommodated in the neck portion. In a color cathode ray tube comprising at least an electron gun for emitting light and a deflecting device mounted on an outer wall of a funnel portion for scanning an electron beam on a phosphor layer, a first grid electrode constituting a prefocus system of the electron gun. , The shape of the center beam passage hole of at least one of the second grid electrode and the third grid electrode is non-circular, and the shape of the side beam passage hole rotates the center beam passage hole according to the characteristics of the deflection device. A color cathode ray tube characterized by having a different shape. 3. An electron beam which is housed in the neck portion, a panel portion having an inner surface coated with a phosphor layer that emits light by electron beam bombardment, a neck portion connected to the panel portion through a funnel portion, and the electron beam. In a color cathode ray tube comprising at least an electron gun for emitting light and a deflecting device mounted on an outer wall of a funnel portion for scanning an electron beam on a phosphor layer, a first grid electrode constituting a prefocus system of the electron gun. A color cathode ray tube characterized in that the area of the center beam passage hole and the area of the side beam passage hole of at least one of the second grid electrode and the third grid electrode are different.