JP2003162967A - Internal magnetic shield of color cathode-ray tube, and color cathode-ray tube with the internal magnetic shield - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal magnetic shield of color cathode-ray tubes which is capable of preventing the occurrence of color shift and color nonuniformity by suppressing mislanding of beams over the entire screen including respective portions at the center, in the middle and at the corners, thereby enabling high definition display. <P>SOLUTION: This internal magnetic shield of color cathode-ray tubes is formed with four metal sheets 1 and 2 having nearly trapezoidal shapes by assembling them as a pyramidal frustum, and a notched portion 4 is formed so as to be nearly rectangular into a shape, of which the one of the long sides is set on the upper side of a sidewall and a symmetrical tapered form 5 is respectively extended, from two positions on the other long side of the rectangle toward the inside of the rectangle. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner magnetic shield for a color cathode ray tube and a color cathode ray tube having the inner magnetic shield.

[0002]

2. Description of the Related Art The structure of a conventional color cathode ray tube having an internal magnetic shield will be described with reference to FIG. Electron gun 85
The electron beam 87 emitted from the panel 81 is deflected by the magnetic field generated by the deflection yoke 89 arranged on the outer periphery of the boundary portion between the large diameter portion of the funnel 82 and the neck 88, and the panel 81 is deflected.
By performing horizontal and vertical scanning on the phosphor screen 83 formed on the inner surface of the, a color image is formed on the phosphor screen 83.

When the geomagnetic field or a magnetic field generated from an external circuit enters the path of the electron beam 87, the electron beam 87 is affected by the magnetic field and deviates from its original orbit, causing so-called mislanding and degrading color purity. Therefore, the electron beam 87 is most likely to be affected by the magnetic field.
An internal magnetic shield 86 is arranged inside the unit 2.

The inner magnetic shield 86 is typically 0.1 to
A metal plate made of a magnetic material having a plate thickness of about 0.3 mm is shown in FIG.
It is obtained by forming into a tubular member having the shape of a truncated pyramid as shown in FIG. The bottom side of the quadrangular pyramid defining the large opening is attached to the color selection electrode 84 by welding or a clip, and the top side of the quadrangular pyramid defining the small opening is arranged in the large diameter portion of the funnel 82 so as to face the electron gun. It

The internal magnetic shield 86 described above has two large trapezoidal thin plates 91 (hereinafter referred to as long side walls) whose upper and lower sides are placed in parallel with the horizontal scanning line as shown in FIG.
And a small trapezoidal thin plate 92 (hereinafter referred to as a short side wall) whose upper side and lower side are placed in parallel with the vertical scanning line in a cylindrical shape. The magnetic shielding effect of this internal magnetic shield is obtained. In order to increase the
No. 236898 discloses that the short side wall 9 as shown in FIG.
It is disclosed to form a pentagonal notch 94 in the shape of a baseball home base on the upper side of the base 2. FIG. 10 shows the structure of a cathode ray tube in which such an internal magnetic shield 86a is arranged.

[0006]

In the above-mentioned conventional internal magnetic shield, the mislanding due to the external magnetic field such as the earth's magnetic field, including the one in which the notch is formed on the short side wall, is larger than that in the center of the screen. There is a tendency for the size to increase in the peripheral part, especially in the corner part of the screen. If the mislanding at the corners of the screen is reduced by adjusting the magnetic field generated by the deflection yoke, the mislanding at the center of the screen peripheral part (hereinafter referred to as the screen peripheral intermediate part) excluding the corner parts becomes large. The problem occurs.

In order to perform high definition display,
It is necessary to suppress mislanding in all parts of the screen, including the peripheral part of the screen and the screen corners.However, as explained above, the conventional internal magnetic shield cannot suppress mislanding in the entire screen. However, it was difficult to meet the demand for high-definition display.

The present invention has been made in view of the above problems, and suppresses mislanding over the entire screen including the screen central portion, screen peripheral intermediate portion, and screen corner portion,
The purpose is to prevent color misregistration and color unevenness and enable high-definition display.

[0009]

[Means for Solving the Problems] In order to achieve the above object,
The invention according to claim 1 is configured by combining four metal thin plates having a substantially trapezoidal shape into a cylindrical shape, and has a substantially rectangular truncated pyramid shape in which cutouts are formed at the upper sides of at least a pair of opposing side walls. In a shape-shaped internal magnetic shield for a color cathode ray tube, the cutout portion is provided inside a substantially rectangular cutout having an upper side of the side wall as one long side, and the side wall is provided at two locations on another long side of the rectangle. It is characterized in that it is projected in a tapered shape which is symmetrical to the left and right.

According to a second aspect of the present invention, in the first aspect of the invention, the distance from the other long side of the rectangle of the tip of the portion projecting in the tapered shape is the short side of the rectangle. Characterized by being shorter than the length.

According to a third aspect of the present invention, in the second aspect of the present invention, the portion projecting in the tapered shape has a triangular shape, and one side of the triangle is short from the tip to the rectangular short side. The other side of the triangle extends from the tip to the other long side of the rectangle.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the other side of the triangle has a V-shaped notch and one side of another triangle symmetrical to the triangle. It is characterized by forming.

According to a fifth aspect of the present invention, in the invention according to the first aspect, the short side of the substantially rectangular shape forms an angle θ with a line perpendicular to the lower side of the side wall so that the short side faces inward. It is characterized in that it extends and the angle θ is in the range of 0 ° to 30 °.

In order to achieve the above object, the invention according to a sixth aspect is such that the internal magnetic shield in the shape of a substantially truncated pyramid according to any one of the first to fifth aspects is provided in a color cathode ray tube. The square pyramid is arranged so that the opening on the upper surface side faces the electron gun and the opening on the bottom surface faces the color selection electrode facing the phosphor screen.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a perspective view of an internal magnetic shield according to a first embodiment of the present invention. The internal magnetic shield is obtained by forming a metal plate made of a magnetic material having a plate thickness of about 0.1 to 0.3 mm into a tubular member having an outer shape of a truncated pyramid. Large opening (bottom of Figure 1)
Is placed in the funnel diameter of the color cathode-ray tube so that the bottom side of the quadrangular pyramid that faces the phosphor screen faces the phosphor screen, and the top side of the quadrangular pyramid that defines the small opening (upper side in FIG. 1) faces the electron gun. It

This internal magnetic shield comprises two large trapezoidal thin plates 1 whose upper and lower sides are placed parallel to the horizontal scanning line.
(Hereinafter, referred to as long side walls) and two small trapezoidal thin plates 2 (hereinafter, referred to as “long side walls”) whose upper and lower sides are placed parallel to the vertical scanning line.
And a short side wall) are combined in a cylindrical shape. A cutout 4 is formed on the upper side of the short side wall 2.

FIG. 2 is a view of the inner magnetic shield according to the first embodiment as viewed from the short side wall. The notch 4 is formed on the short side wall 1
Two symmetrical left and right first cutting edges 6 extending from a corner of the upper edge in a direction perpendicular to the lower edge of the side wall 1, and left and right extending upward from the tip of the cutting edge 6 at a constant angle with the cutting edge 6. A symmetrical second cutting edge 7, two symmetrical third cutting edges 8 extending downward from the tip of the second cutting edge 7 at a constant angle with the second cutting edge 7, and the two second cutting edges 7. One fourth cutting side 9 that connects the ends of the three cutting sides 8 and is parallel to the lower side of the side wall 1
Formed from.

As shown in FIG. 2, the notch 4 has a rectangular shape in which the upper side of the trapezoidal short side wall is one long side, and the notch 4 has a triangular shape protruding from the other long side of the rectangle. Two projecting portions 5 having a shape are symmetrically arranged.

One apex of the bottom side of the triangular protrusion 5 coincides with two corners of the lower side of the rectangle, and the distance between the other apexes of the bottom sides of the two protrusions 5 is L. In FIG. 2, H represents the height of the internal magnetic shield, and H2
Represents the depth of the notch 4, and H1 represents the height of the protrusion 5.

In FIG. 3, the mislanding amount of the corner portion of the screen of the color cathode ray tube having a diagonal size of 41 cm, the middle portion of the screen periphery, and the end of the horizontal line (x-axis end) passing through the center of the screen is determined as described above. In the case of using the internal magnetic shield of the first aspect, the case of using the conventional internal magnetic shield having no notch, and the case of using the magnetic shield having the notch but having no protrusion Show.

As is apparent from FIG. 3, when the internal magnetic shield of the first embodiment is used, the mislanding amounts at the screen corner portion, the screen peripheral intermediate portion, and the x-axis end portion are all small and almost the same. Has become. This is because the geomagnetism in the tube axis direction is attracted to the first cutting edge 6 and its tip, and the action of the external magnetic field such as the geomagnetism received by the electron beam before reaching the phosphor screen is offset by the action of the attracted magnetic field. This is because the mislanding amount at the corner portion of the screen becomes small and the mislanding amount at the screen peripheral intermediate portion also becomes small due to the similar action of the cut sides 7 and 8 of the protruding portion 5. H1 and H
The value of 2 is appropriately set according to the type of color cathode ray tube so that the mislanding amount is most suppressed.

Embodiment 2. FIG. 4 is a view of the inner magnetic shield according to the second embodiment of the present invention as viewed from the short side wall. As shown in the figure, in the second embodiment, the length of the fourth cutting side 9 is set to 0, and the pair of third cutting sides 8 form a V-shaped notch. By using the internal magnetic shield of the second embodiment, it is possible to reduce the mislanding amount especially near the center of the screen.

Embodiment 3. FIG. 5 shows a view of the inner magnetic shield according to the third embodiment of the present invention as viewed from the short side wall. As shown in the figure, in the third embodiment, the first cutting side 6 does not extend perpendicularly to the bottom side of the short side wall, but a certain angle θ.
It differs from the first embodiment in that it extends inward. The value of θ can be set arbitrarily, but if it exceeds 30 °, the amount of mislanding increases due to the influence of an external magnetic field such as the earth's magnetism, so 0 ° ≦ θ <30 ° is preferable. By using the internal magnetic shield of the third embodiment, it becomes possible to deal with various color cathode ray tubes having different deflection characteristics by adjusting the value of θ.

FIG. 6 shows the structure of a color cathode ray tube having the internal magnetic shield of the above embodiment. In FIG. 6, elements that are the same as or correspond to the elements shown in FIG. 7 are assigned the same reference numerals, and repeated explanations are omitted. The internal magnetic shield 36 generates a magnetic field that cancels the action of the electron beam 87 reaching the phosphor screen 83 from an external magnetic field such as the earth's magnetism, and reduces the mislanding amount on the entire screen. An image with less unevenness can be obtained.

In the internal magnetic shields of the first to third embodiments, the notch 4 and the protrusion 5 are provided on the short side wall, but they may be provided on the long side wall, or the short side wall. And may be provided on both the long side walls. In addition, in the internal magnetic shields of the first to third embodiments, each cut side of the cutout portion 4 is linear, but as long as it is possible to reduce the mislanding amount to a desired value, all or a part thereof can be reduced. It may have a curved shape.

[0026]

According to the invention described in claims 1 to 3,
Mislanding is suppressed over the entire screen including the center part of the screen, the middle part of the screen periphery, and the screen corner part, and color misregistration,
It is possible to obtain an internal magnetic shield that prevents the occurrence of color unevenness and enables high-definition display.

According to the invention of claim 4, claim 1
In addition to the effects of the inventions described in 3 to 3, the mislanding amount can be reduced particularly near the center of the screen.

According to the invention of claim 5, claim 1
In addition to the effects of the inventions described in 3 to 3, it becomes possible to deal with various color cathode ray tubes having different deflection characteristics.

According to the invention described in claim 6, color shift,
It is possible to obtain a color cathode ray tube capable of performing high-definition display with less color unevenness over the entire screen.

[Brief description of drawings]

FIG. 1 is a perspective view of an internal magnetic shield according to a first embodiment of the present invention.

FIG. 2 is a view of the inner magnetic shield according to the first embodiment as seen from a short side wall thereof.

FIG. 3 is a graph showing the amount of mislanding of a color cathode ray tube in comparison with the case where the internal magnetic shield of the first embodiment is provided and the case where the conventional internal magnetic shield is provided.

FIG. 4 is a view of an inner magnetic shield according to a second embodiment of the present invention as viewed from a short side wall thereof.

FIG. 5 is a view of an inner magnetic shield according to a third embodiment of the present invention as seen from its short side wall.

FIG. 6 is a diagram showing a configuration of a color cathode ray tube provided with an internal magnetic shield of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional color cathode ray tube including an internal magnetic shield.

FIG. 8 is a perspective view of a conventional internal magnetic shield.

FIG. 9 is a perspective view of another conventional internal magnetic shield.

10 is a diagram showing a configuration of a color cathode ray tube including the internal magnetic shield of FIG.

[Explanation of symbols]

1 long side wall, 2 short side wall, 4 notch, 5
Protrusion, 6 first cutting side, 7 second cutting side, 8
3rd cutting edge, 9 4th cutting edge, 36 internal magnetic shield, 81 panel, 82 funnel, 83
Phosphor screen, 84 color selection electrode, 85 electron gun, 86 internal magnetic shield, 87 electron beam, 88 neck, 89 deflection yoke, 91 long side wall, 92 short side wall, 94 notch.

Claims (6)

[Claims] 1. A color cathode wire in the shape of a substantially quadrangular pyramid that is formed by combining four metal thin plates having a substantially trapezoidal shape into a tubular shape and has cutouts formed on the upper sides of at least a pair of opposing side walls. In the internal magnetic shield for a tube, the cutout portion is symmetrical inside the substantially rectangular cutout having the upper side of the side wall as one long side, and the side wall is symmetrical from two locations on the other long side of the rectangle. An internal magnetic shield for a color cathode ray tube, which is characterized by protruding in a tapered shape. 2. The color cathode ray tube according to claim 1, wherein a distance of a tip of the tapered projecting portion from another long side of the rectangle is shorter than a length of a short side of the rectangle. Internal magnetic shield for tubes. 3. The tapered projecting portion has a triangular shape, and one side of the triangle extends from the tip to the short side of the rectangle, and another side of the triangle extends from the tip. The inner magnetic shield for a color cathode ray tube according to claim 2, wherein the inner magnetic shield extends to the other long side of the rectangle. 4. The color cathode ray tube according to claim 3, wherein the other side of the triangle forms a V-shaped cutout with one side of another triangle which is symmetrical to the triangle. Internal magnetic shield. 5. The short side of the substantially rectangular shape extends at an angle θ with a line perpendicular to the lower side of the side wall so that the short side faces inward, and the angle θ is in the range of 0 ° to 30 °. An inner magnetic shield for a color cathode ray tube according to claim 1, wherein: 6. An internal magnetic shield in the shape of a substantially truncated pyramid according to claim 1, wherein the opening on the top side of the truncated pyramid faces the electron gun and the opening on the bottom side A color cathode ray tube characterized in that it is arranged so as to face a color selection electrode facing a phosphor screen.