JP2002184319A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent halation being caused when electron beams are overscanned. SOLUTION: Long side skirts 210a, 210b are formed at the lower side bottom sides of a pair of long side side-plates 201a, 201b of nearly trapezoidal form of an inner magnetic shield 200. The long side skirt has a long side first skirt 211a, 211b and a long side second skirt 212a, 212b in order from the long side side-plate side. The long side first skirt is installed nearly to cross the tube axis at right angles and so as to be opposed to the face of the electron gun side of the frame 110, and the long side second skirt is arranged nearly in parallel with the tube axis and so as to be opposed to the outside wall face of the frame. The electron beams crash against the long side first or second skirt and are reflected. Therefore they do not pass through between the inner magnetic shield and the frame and arrive at the front face panel. Hence a cathode-ray tube having no halation is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube. In particular, the present invention relates to a cathode ray tube provided with an internal magnetic shield that reduces a landing position shift of an electron beam due to an external magnetic field such as terrestrial magnetism.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 10-261369 discloses that
A color cathode ray tube with an internal magnetic shield is described. Hereinafter, a conventional color cathode ray tube will be described with reference to the drawings.

FIG. 8 is an exploded perspective view showing a schematic structure of a conventional color cathode ray tube. For convenience of the following description, as shown in the figure, a horizontal direction (long side direction) passing through the pipe axis and perpendicular to the pipe axis is an X axis, a vertical direction passing through the pipe axis, and perpendicular to the pipe axis. (Short side direction) An XYZ-three-dimensional orthogonal coordinate system is set, in which the axis is the Y axis and the tube axis is the Z axis.

[0004] The front panel 801 and the funnel 802 are integrated to form an envelope. A phosphor screen 803 is formed on the inner surface of the front panel 801, and an aluminum thin film layer 804 is formed thereon.

[0005] A color selection electrode (for example, a shadow mask) is separated from and opposed to the phosphor screen 803.
805 is mounted on the frame 810 so as to be stretched.

The frame 810 includes a pair of long side frames 811a and 811 arranged in parallel at a predetermined distance from each other.
b and a pair of short side frames 812a and 812b arranged in parallel at a predetermined distance from each other. The long side frames 811a and 811b are formed by bending a metal plate so that its cross section is substantially L-shaped, and a color selection electrode 805 is stretched over its free end. Short side frames 812a, 812b
Is formed by bending a square pillar-shaped metal pillar into a substantially U-shape. A pair of long side frames 811a, 811
b and a pair of short side frames 812a and 812b are combined in a substantially rectangular frame shape, and the joint is welded to form a frame 810.
Is configured.

The long side frame 811a of the frame 810,
811b and the outer side walls of the short side frames 812a, 812b are provided with elastic supports 815a, 815b, 8 in the form of leaf springs.
16a and 816b are respectively attached. Panel pins 805a, 805b, 806a, 806b (panel pins 805a, 806a not shown) implanted on the inner surface of front panel 801 are respectively fitted into holes provided in elastic supports 815a, 815b, 816a, 816b. Thus, the frame 810 is held in the front panel 801.

[0008] An electron gun (not shown) is incorporated in the neck 802 a of the funnel 802. A deflection yoke (not shown) is provided on the outer peripheral surface of the funnel 802. The electron beam emitted from the electron gun is deflected by the deflection yoke in the X-axis direction and the Y-axis direction, and scans the phosphor screen 803.

When an external magnetic field such as terrestrial magnetism acts on the cathode ray tube, the trajectory of the electron beam changes, and the electron beam does not reach a desired position on the phosphor screen 803, so that a so-called "mislanding" occurs. As a result, undesired phenomena such as color misregistration occur in the color cathode ray tube, and the quality of the displayed image is reduced. The direction of the external magnetic field varies depending on the installation direction of the cathode ray tube, and the magnitude thereof differs depending on the installation position of the cathode ray tube. Therefore, in order to always perform stable image display irrespective of the installation direction and the installation position of the cathode ray tube, the electron beam is shielded from the external magnetic field or the external magnetic field is converted into a magnetic field at least in a direction that does not cause mislanding. There is a need. For such a purpose, an internal magnetic shield 830 is provided in a region between the frame 810 and the deflection yoke in the Z-axis direction.

FIG. 9 is a schematic perspective view of the internal magnetic shield 830.

The internal magnetic shield 830 has a pair of substantially trapezoidal opposed long side plates 831a and 831b and a pair of substantially trapezoidal opposed short side plates 832a and 832b, which are formed in a substantially quadrangular pyramid shape. Are formed so as to form a part of each other. Long side skirts 833a and 833b bent to be substantially parallel to the XZ plane are provided on the sides (lower bottom sides) of the long side plates 831a and 831b on the frame 810 side.
(The long side skirt 833b is not shown). Also, the frame 81 of the short side plates 832a and 832b
On the 0 side (lower bottom side), short side skirts 834a and 834b (short side skirt 834b not shown) bent to be substantially parallel to the YZ plane, and a short side frame of frame 810 Joint portions 835a and 835b for joining with 812a and 812b are formed.

FIG. 10 is a side view of a color selection structure in which the internal magnetic shield 830 and the frame 810 are integrated.

The joint 835 of the internal magnetic shield 830
a, 835b are brought into contact with the electron gun side surfaces of the short side frames 812a, 812b while the long side skirts 833a, 833b
The inner magnetic shield 830 is integrated with the frame 810 by spot welding the 33b and the outer wall surfaces of the long side frames 811a and 811b.

The long side skirts 833a and 833b are provided with notches 837a and 837b (not shown) for avoiding interference with the elastic supports 815a and 815b attached to the long side frames 811a and 811b.
And a notch 838 for transporting the internal magnetic shield 830
a, 838b (notches 838b are not shown).

[0015]

In recent years, cathode ray tubes have
The ability to display a high-definition image without distortion even at the upper, lower, left, and right ends of the display area is particularly required. In order to meet such a demand, the electron beam may be scanned (that is, overscanned) even to a region outside an effective region for displaying an image.

However, when such an overscan is performed, halation occurs at both ends in the vertical direction of the screen, causing a problem that the display quality is deteriorated. The present inventors have intensively studied the cause and found the following generation mechanism.

FIG. 11 is a sectional view taken along the line XI-XI in FIG. In FIG. 11, the front panel 8
01 and funnel 802 are also shown.

In the overscan of the electron beam, the electron beam is deflected to a trajectory 807b further outside the trajectory 807a of the electron beam for displaying an image at the end of the effective display area Wy in the Y-axis direction.

In a cathode ray tube for performing such overscan, as shown in the figure, an internal magnetic shield 830 is provided.
When the notch 837a exists in the long side skirt 833a, the electron beam describing the trajectory 807b is notched 837a.
, And collides with the aluminum thin film layer 804 on the inner surface of the front panel 801, repeatedly reflects between the aluminum thin film layer 804 and the long side frame 811 a, reaches the formation region of the phosphor screen 803, and becomes abnormal. This produces luminescence. This was observed as halation on the display screen.

In FIG. 11, the cause of the occurrence of halation is described using the cross section of the notch 837a, but the same phenomenon also occurs in the notch 838a. In addition, the same occurs in the notch portions 837b and 838b of the opposing long side skirt 833b.

An object of the present invention is to solve the above-mentioned problems of the conventional cathode ray tube and to provide a cathode ray tube in which the occurrence of halation is suppressed even when an electron beam is overscanned.

[0022]

The present invention has the following configuration to achieve the above object.

The cathode ray tube according to the present invention comprises an envelope comprising a front panel and a funnel, a phosphor screen formed on the inner surface of the front panel, and a color selection electrode arranged opposite to the phosphor screen. A substantially rectangular frame holding the color selection electrode, an electron gun installed in the funnel, and an internal magnetic shield held by the frame and installed on the electron gun side of the color selection electrode. A cathode ray tube having the internal magnetic shield, a pair of substantially trapezoidal long side plates disposed to face each other,
A pair of substantially trapezoidal short side plates arranged opposite to each other, and a long skirt connected to a lower bottom of the long side plate, wherein the pair of long side plates and the pair of short side plates are provided. And are combined to form a part of a substantially quadrangular pyramid surface,
The long side skirt is a long side first side in order from the long side side plate side.
A skirt and a second skirt on a long side, wherein the first skirt on the long side is installed so as to be substantially perpendicular to a tube axis and opposed to a surface of the frame on the electron gun side; The skirt is substantially parallel to the tube axis and is arranged so as to face the outer wall surface of the frame.

As described above, the first long side skirt and the second long side skirt are connected to the long side plate in this order. The first long side skirt is arranged so as to face the surface of the frame facing the electron gun, and the second long side skirt is arranged so as to face the outer wall surface of the frame. Therefore, even if the electron beam is overscanned, it is possible to prevent the electron beam from passing between the internal magnetic shield and the frame and reaching the front panel. As a result, a cathode ray tube without halation can be obtained.

In the above configuration, it is preferable that the first long side skirt is formed with a step, and the first long side skirt is discontinuous at the step portion of the first long side skirt. According to such a preferred configuration, the discontinuous portion acts as a magnetic resistance with respect to the magnetic field in the long side direction flowing in the long side first skirt to block the magnetic flux. Therefore, mislanding of the electron beam due to the external magnetic field in the long side direction can be prevented, and a cathode ray tube with less color shift can be provided. In order to make the long side first skirt discontinuous, an opening or a notch may be provided in the long side first skirt.

In the above preferred configuration, the step may be provided corresponding to a step on a surface of the frame on the electron gun side. That is, when the surface of the frame on the electron gun side has a step, it is preferable to form a step on the long side first skirt along the step. According to this preferred configuration, it is possible to prevent the electron beam from leaking out of the internal magnetic shield from the discontinuous portion at the step portion of the first skirt on the long side. In addition, since the frame has a step, the step acts as a magnetic resistance against a magnetic field passing through the frame, thereby preventing mislanding of the electron beam.

In the case where a step is provided in the first long side skirt, a connecting plate is connected to at least a part of the lower bottom side of the long side plate corresponding to the step, and the first side skirt of the long side is provided. It is preferable that at least a part is connected to the long side plate via the connection plate. Here, in the present invention, the “lower bottom side” means a longer side of a pair of parallel sides of a long side plate (or a short side plate) having a substantially trapezoidal shape.
Note that the other shorter side is referred to as “upper bottom side”. According to such a preferred configuration, the overscanned electron beam collides with the connecting plate and is reflected,
It can be prevented from passing between the internal magnetic shield and the frame to reach the front panel. As a result, a cathode ray tube without halation can be obtained.

In addition, it is preferable that a slit is formed along a connection portion between the long side plate and the first long side skirt at the connection portion. When a connection plate is interposed between the long side plate and the long side first skirt, a slit along the connection portion is formed at a connection portion between the connection plate and the long side first skirt. Preferably, it is formed. According to such a preferred configuration, the slit acts as a magnetic resistance to the magnetic field in the long side direction flowing in the internal magnetic shield, and blocks the magnetic flux flowing from the long side plate to the long side skirt side. Therefore,
Mislanding of an electron beam due to an external magnetic field in the long side direction can be prevented, and a cathode ray tube with less color shift can be provided.

Preferably, the internal magnetic shield is made of a material having a higher magnetic permeability than the frame. According to such a preferred configuration, the magnetic field in the long side direction passes not through the frame but through the internal magnetic shield. as a result,
By giving the internal magnetic shield various shapes that function as a magnetic resistance, mislanding of the electron beam due to an external magnetic field in the long side direction can be easily prevented.

It is preferable that an electron shield plate is provided along the shorter side of the frame, protruding toward the tube axis from the frame. According to such a preferable configuration, it is possible to prevent halation due to leakage of the electron beam from the short side.

[0031]

FIG. 1 is a cross-sectional view of a color cathode ray tube 100 according to an embodiment of the present invention, taken along a vertical axis passing through a tube axis. 8 to 11, the horizontal direction (long side direction) passing through the tube axis and perpendicular to the tube axis is the X axis, and the vertical direction passing through the tube axis and perpendicular to the tube axis (short side direction). The axis is the Y axis,
An XYZ-three-dimensional orthogonal coordinate system with the tube axis as the Z axis is set.

The front panel 101 and the funnel 102 are integrated to form an envelope 103. Front panel 10
A phosphor screen 104 is formed on the inner surface of the device 1, and an aluminum thin film layer (not shown) similar to that shown in FIG. 11 is formed thereon. A color selection electrode 105 is provided so as to span the frame 110 so as to be spaced from and opposed to the phosphor screen 104. Frame 1
Reference numeral 10 denotes that a leaf spring-like elastic support (not shown) installed on the outer wall surface is hung on a panel pin (not shown) planted on the inner surface of the front panel 101, as in the related art. At the front panel 101. An electron gun 106 is built in the neck of the funnel 102. A deflection yoke 108 is provided on the outer peripheral surface of the funnel 102, whereby the electron beam 107 from the electron gun 106 is deflected in the horizontal and vertical directions, and scans the phosphor screen 104. An internal magnetic shield 200 is attached to the frame 110. The internal magnetic shield 200 is installed in a region between the frame 110 and the deflection yoke 108 in the Z-axis direction.

FIG. 2 is an exploded perspective view of a color selection structure including a frame 110 on which a color selection electrode 105 is stretched and an internal magnetic shield 200.

The frame 110 is made up of a pair of long side frames 111a, 111 arranged in parallel at a predetermined distance.
b, and a pair of short side frames 112a and 112b arranged at a predetermined distance from each other. Long side frame 11
1a and 111b are formed by bending a metal plate into a substantially L-shaped cross section. The short side frames 112a and 112b are formed by bending a square pillar-shaped metal pillar into a substantially U-shape.
A pair of short side frames 112a and 112b are installed on the side surfaces of the pair of long side frames 111a and 111b so as to form a substantially rectangular frame shape as shown in FIG. The frame 110 is preferably made of a material having a lower magnetic permeability than the internal magnetic shield 200 (for example, a steel plate). Thereafter, a color selection electrode 105 is stretched over free ends of the pair of long side frames 111a and 111b on the phosphor screen side. As the color selection electrode 105, for example, a shadow mask in which a large number of openings are arranged and formed can be used.

On the outer wall surfaces of the pair of long side frames 111a, 111b and the pair of short side frames 112a, 112b, leaf spring-like elastic supports 115a, 115b, 116a, 116 for attaching the color selection structure to the front panel are provided.
b is attached (the elastic support 115b is not shown).

The internal magnetic shield 200 has a pair of substantially trapezoidal opposed long side plates 201a and 201b and a pair of substantially trapezoidal opposed short side plates 202a and 202b. Are formed in combination so as to form a part of. The internal magnetic shield 200 is preferably manufactured using a material having a high magnetic permeability (for example, an invar material or a mild steel material) by a known method such as pressing.

Frame 1 of long side plates 201a and 201b
A long side skirt 210a,
210b is formed. Long side skirt 210a, 2
10b is a long side first skirt 21 substantially parallel to the XY plane.
1a, 211b, and long side first skirts 211a, 211
b, and has long side second skirts 212a and 212b substantially parallel to the XZ plane.

The first long side skirts 211a and 211b are
The frame 110 is formed with a step in the Z-axis direction so as to correspond to the position on the electron gun side of the frame 110 in the Z-axis direction. That is, both ends of the first skirts 211a and 211b on the long side are closer to the electron gun, and the central portion therebetween is the frame 110.
It is placed closer. The long side first skirts 211a, 211b and the long side plates 201a, 201b, which are arranged near the center of the frame 110, are connected to the connection plates 215a, 215b.
Connected through. Connection plates 215a, 215b
Is substantially parallel to the XZ plane. Each of the step portions of the long side first skirts 211a and 211b is cut so as to cut the long side first skirts 211a and 211b extending in the X-axis direction.
An opening 216 that opens in the axial direction is formed.

Similarly, the short side skirt 2 is provided on the side (lower bottom side) of the short side plates 202a and 202b on the frame 110 side.
20a and 220b are formed. Short side skirt 22
0a and 220b are short-side first skirts 221a and 221b substantially parallel to the XY plane, and short-side first skirt 221.
a, 221b and the short side second skirts 222a, 222b (short side second skirt 22) substantially parallel to the YZ plane.
2b is not shown). Short side second skirt 222
a and 222b are each divided into two in the Y-axis direction to avoid interference with the elastic supports 116a and 116b installed on the short side frames 112a and 112b.

At the connection between the connection plates 215a and 215b and the first long side skirts 211a and 211b, an elongated first slit 203 whose longitudinal direction is in the X-axis direction is formed.

Further, a pair of long side plates 201a, 201b
An elongated second slit 204 is formed along the trajectory of the electron beam (that is, so as to connect the upper base and the lower base of the substantially trapezoidal long side plate).

By providing the first slit 203 and the second slit 204, it is possible to prevent a change in the electron beam trajectory due to an external magnetic field in the X-axis direction (hereinafter referred to as "transverse magnetic field"). As a result, color shift of the displayed image can be prevented. The reason is as follows.

The magnetic flux due to the transverse magnetic field is absorbed by one of the short side plates (for example, the short side plate 202a), and
a, 201b is formed so as to pass through the inside of the X-axis direction and pass through the other short side plate (for example, the short side plate 202b) to the outside. The second slit 204 has a long side plate 201a,
Such a transverse magnetic field passing through the inside 201b acts as a magnetic resistance. Therefore, the transverse magnetic field tends to flow in the long side skirts 210a and 210b, avoiding the second slit 204. At this time, the long side plates 201a, 201
By forming the first slit 203 in the region between the first skirt 210b and the first skirts 210a and 210b, the flow of such a transverse magnetic field can be blocked. As described above, the transverse magnetic field passing through the inner magnetic shield can be reduced, the landing position shift of the electron beam can be prevented, and the cathode ray tube with less color shift can be provided.

Furthermore, the long side first skirts 211a, 211
If the b is formed discontinuously in the X-axis direction by providing the above-described opening 216, the long side first skirt 211
a, 211b against the transverse magnetic field passing through
Can act as a magnetic resistance, and the magnetic flux can be cut off. As a result, a landing position shift of the electron beam due to the lateral magnetic field can be prevented, and a cathode ray tube with less color shift can be provided. When the frame 110 is made of a material having a lower magnetic permeability than the internal magnetic shield 200, the transverse magnetic field tends to pass through the first long skirts 211a and 211b instead of the long side frames 111a and 111b.
The above effects are more remarkably exhibited.

The short side frames 112a of the frame 110,
A pair of electron shield plates 170a, 170b is provided between the inner magnetic shield 200 and the short side first skirts 221a, 221b of the internal magnetic shield 200. End portions 171 of the electron shield plates 170a and 170b on the tube axis side.
a, 171b are installed so as to protrude toward the pipe axis from the ends of the short side frames 112a, 112b on the pipe axis side.
The electron shield plates 170a and 170b reflect the electron beam toward the electron gun when the trajectory of the electron beam deviates from the original trajectory in the X-axis direction due to overscan or other reasons. As a result, the electron beam is transmitted to the short side frames 112a and 112b and the short side second skirt 222.
a, 222b, and is reflected to the color selection electrode 105 side to disturb the displayed image or to make the short side skirts 220a, 220b.
0b and the color selection electrode 105 to prevent the occurrence of halation.

Electron shield plates 170a, 170
b, short side first skirt 22 of internal magnetic shield 200
1a and 221b are the respective welding points 291 and 17
3 is spot welded and integrated. Next, this is combined with the frame 110, and the short side first skirts 221a, 221a
21b and the short side frames 112a and 112b are spot-welded at the welding locations 292 and 117 to form the long side second skirt 212.
a, 212b and the long side frames 111a, 111b are spot-welded at welding locations 293, 118. Thus, the color selection structure of the present embodiment is obtained.

X-axis slits 225 are formed on both sides of the short side first skirts 221a, 221b in the Y-axis direction of the welding location 292 so as to sandwich the welding location 292. In the short side first skirts 221a and 221b, the region including the welded portion 292 sandwiched between the pair of slits 225 is displaced toward the frame 110 from the other region. By forming such a slit 225 and displacing the short-side first skirts 221a and 221b, the internal magnetic shield 200 and the short-side frames 112a and 112b are brought into close contact with each other near the welding points 292 and 117, and the Strength can be improved.

FIG. 3 is a schematic perspective view of the color selection structure thus obtained. The ends of the short side frames 112a and 112b are exposed in the opening 216.

In FIG. 3, IV-IV line, VV line,
Sectional views of the lines VI-VI and VII-VII viewed from the direction of the arrows are shown in FIG. 4, FIG. 5, FIG. 6, and FIG.

As shown in FIGS. 4 to 6, the second long side skirt 212a is in close contact with the outer wall surface of the long side frame 111a. Further, the first skirt 211a on the long side is separated from the opposite short side frame 112b (or 112a) or the long side frame 111a by a predetermined distance substantially parallel to the surface thereof. With such a configuration, the orbit 107
The electron beam that is overscanned in the Y-axis direction and travels along the short side b collides with the short side frame 112b (FIG. 4) or the connection plate 215a (FIGS. 5 and 6), and is reflected toward the electron gun. . As shown in FIG. 6, the electron beam that is overscanned so as to pass through the first slit 203 along the trajectory 107c has a length substantially parallel to the XY plane after passing through the first slit 203. Side first skirt 211
On a, it is reflected to the opposite side of the phosphor screen (not shown). 4 to 6, reference numeral 107a denotes the trajectory of the electron beam for displaying an image at the end of the effective display area in the Y-axis direction.

As described above, according to the present invention, the long side second skirt 212a is brought into close contact with the outer wall surface of the long side frame 111a, and the long side first skirt 211a is connected to the short side frame 1
Since the electron beams 12a and 112b or the long side frame 111a are arranged along the surface on the electron gun side, the electron beam overscanned in the Y-axis direction passes between the long side skirt 210a and the long side frame 111a. And does not reach the phosphor screen. Therefore, halation, which has conventionally been a problem, can be prevented. 4 to 6
Has been described using one long side (long side frame 111a side) as an example, but the other long side (long side frame 111b side) is completely the same.

As is clear from FIG. 6, the first slit 2
If the opening width of the 03 in the Z-axis direction is too large, the electron beam that has passed through the first slit 203 is not
a, 211b, without reaching the inner surface of the front panel, causing halation as in the case of the track 807b in FIG. Therefore, the opening width of the first slit 203 in the Z-axis direction is usually 3 mm or less, preferably 2 mm or less.

The electron beam may be overscanned also in the X-axis direction. However, in the present embodiment, as shown in FIG. 7, the electron beam traveling over the orbit 107e and overscanned in the X-axis direction emits the electron shield plate 170a protruding toward the tube axis.
After the collision, the light is reflected toward the electron gun, so that halation does not occur. In FIG. 7, 10
Reference numeral 7d denotes the trajectory of the electron beam for displaying an image at the end of the effective display area in the X-axis direction. FIG. 7 illustrates one short side (short side frame 112a side) as an example, but the other short side (short side frame 112b side) is completely the same.

In the above example, the long side second skirt 212
The positions of the ends a and 212b on the color selection electrode 105 side in the Z-axis direction are not the same in the X-axis direction but are changed stepwise, but the present invention is not limited to this. For example,
Color selection electrode 10 of long side second skirt 212a, 212b
The end on the fifth side may be formed in a straight line, or may be partially cut away to avoid interference with the elastic supports 115a and 115b or to transport the internal magnetic shield. . However, in order to prevent the leakage of the electron beam, at least a part of the second skirts 212a and 212b on the long side has an outer wall surface of the frame 110 (that is, the long side frames 111a and 111a) over the entire length in the X-axis direction.
11B, the outer side wall of either of the short side frames 112a and 112b).

In the above example, the long side second skirt 212
Although at least a part of the first and second long skirts 212a and 212b are in close contact with the outer wall surface of the frame 110,
It is sufficient that 212b is disposed so as to face the outer wall surface of frame 110, and does not need to be in close contact with the outer wall surface of frame 110. That is, there is a substantially parallel gap of 0.2 mm or less, more preferably 0.1 mm or less, between the long side second skirts 212a and 212b and the outer wall surface of the frame 110 within a range that can prevent electron beam leakage. May be.

In the above example, the short side frame 112
The steps a and 112b are formed on the surface of the long-side frames 111a and 111b on the electron gun side, so that a step is formed on the surface of the frame 110 on the electron gun side. The frame of the present invention has such a configuration. Not limited. For example, a frame in which the long side frame and the short side frame are joined so that the surfaces on the electron gun side of the long side frame and the short side frame form the same plane, or the frame 810 shown in FIG. Frame may be used. In the former case, the steps of the long side first skirts 211a and 211b, the openings 216 of the step portions, and the connection plates 215a and 215b are unnecessary. When the first slit 203 is provided, the lower bottom side of the long side plate is used. It may be provided along. However, the frame 110 described in the specific example above has the opening 216
In addition, the effect of the magnetic resistance of the stepped portion of the frame can be obtained, which is preferable from the viewpoint of preventing mislanding of the electron beam.

The long side first skirts 211a, 211
b has been set apart from the long side frames 111a and 111b and the short side frames 112a and 112b. As in the above example, the long side second skirts 212a, 212b
Is not in close contact with the outer wall surface of the frame 110 over the entire length in the X-axis direction,
a, 211b and the long side frames 111a, 111b, and the short side frames 112a, 112b are too large.
This causes leakage of the electron beam and causes halation.
Therefore, in such a case, the gap is 5 mm or less,
Further, it is preferably 3 mm or less. Although both can be brought into close contact with each other, it is preferable to separate them from each other since the flow of the magnetic field between the two can be cut off, and from the viewpoint of preventing mislanding of the electron beam.

In the above example, the connection plates 215a, 215
5b is formed substantially parallel to the XZ plane, but the present invention is not limited to this. That is, the opposing connection plate 215
The connection plates 215a and 215b may be inclined so that the distance between the a and 215b becomes wider on the color selection electrode 105 side.
However, when the inclination angle increases, the connection plate 215
a, long side first skirt 211a connected to
6, the electron beam passing through the first slit 203 reaches the inner surface of the front panel without colliding with the long-side first skirts 211a and 211b. Halation is generated as in the case of the eleven trajectories 807b. Therefore, the connection plate 215
The inclination angle of the a and 215b with respect to the Z axis is preferably 45 degrees or less, more preferably 60 degrees or less.

Further, the short side second skirt 222a,
The 222b is divided into two parts in the Y-axis direction to avoid interference with the elastic supports 116a and 116b. However, if the interference with the elastic supports 116a and 116b can be avoided, it should be completely divided into two parts. Instead, a part of the electron gun may be continuous.

Further, a well-known notch such as a V-shape may be provided on the upper bottom side (the end on the electron gun side) of the short side plates 202a and 202b.

[0061]

As described above, according to the present invention, it is possible to prevent an overscanned electron beam from reaching the front panel by passing between the internal magnetic shield and the frame. As a result, a cathode ray tube without halation can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color cathode ray tube of the present invention.

FIG. 2 is an exploded perspective view showing a configuration of a color selection structure used in the color cathode ray tube of the present invention.

FIG. 3 is an overall perspective view of a color selection structure used in the color cathode ray tube of the present invention.

FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG.

FIG. 5 is a cross-sectional view taken along the line VV in FIG.

FIG. 6 is a cross-sectional view taken along a line VI-VI in FIG.

FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG.

FIG. 8 is an exploded perspective view showing a schematic configuration of a conventional color cathode ray tube.

FIG. 9 is a schematic perspective view of an internal magnetic shield used in the color cathode ray tube of FIG.

FIG. 10 is a side view of a color selection structure used in the color cathode ray tube of FIG.

11 is a cross-sectional view taken along the line XI-XI in FIG.

DESCRIPTION OF SYMBOLS 100 color cathode ray tube 101 front panel 102 funnel 103 envelope 104 phosphor screen 105 color selection electrode 106 electron gun 107 electron beam 108 deflection yoke 110 frame 111a, 111b long side frame 112a, 112b short side frame 115a , 115b, 116a, 116b Elastic support 117, 118 Welding point 170a, 170b Electron shield plate 171a, 171b Tube shaft end 173 Welding point 200 Internal magnetic shield 201a, 201b Long side plate 202a, 202b Short side plate 203 No. 1 slit 204 2nd slit 210a, 210b Long side skirt 211a, 211b Long side first skirt 212a, 212b Long side second skirt 215a, 215b Connection plate 216 Opening 220a, 220b Short side skirt 221a, 221b Short side first skirt 222a, 222b Short side second skirt 225 Slit 291, 292, 293 Welding point

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takayuki Yonezawa 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. (72) Inventor Hideo Iguchi 1-1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics (72) Inventor Tomohisa Mikami 1-1, Yukicho, Takatsuki-shi, Osaka Prefecture Matsushita Electronics Co., Ltd. (72) Inventor Yoko Henan 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 5C031 CC02 CC09

Claims (8)

[Claims] 1. An envelope comprising a front panel and a funnel, a phosphor screen formed on an inner surface of the front panel, a color selection electrode arranged to face the phosphor screen, and the color selection electrode A cathode ray tube having a substantially rectangular frame-shaped frame for holding the electron gun, an electron gun installed in the funnel, and an internal magnetic shield held on the frame and installed on the electron gun side from the color selection electrode. Wherein said internal magnetic shield comprises: a pair of substantially trapezoidal long side plates disposed to face each other; a pair of substantially trapezoidal short side plates disposed to face each other; A long side skirt connected to a side bottom side, wherein the pair of long side plates and the pair of short side plates are combined so as to form a part of a substantially quadrangular pyramid surface; The skirt is on the long side plate side Long side first
A skirt and a second long-side skirt, wherein the first long-side skirt is disposed so as to be substantially orthogonal to a tube axis and to face a surface of the frame on the electron gun side; The cathode ray tube, wherein the skirt is disposed substantially parallel to the tube axis and opposed to an outer wall surface of the frame. 2. The cathode ray tube according to claim 1, wherein the first long side skirt is formed with a step, and the first long side skirt is discontinuous at the step portion of the first long side skirt. . 3. The cathode ray tube according to claim 2, wherein the step corresponds to a step on a surface of the frame on the electron gun side. 4. A connecting plate is connected to at least a part of a lower bottom side of the long side plate corresponding to the step, and at least a part of the long side first skirt is connected to the long side via the connecting plate. The cathode ray tube according to claim 2, which is connected to a side plate. 5. The cathode ray tube according to claim 1, wherein a connecting portion between the long side plate and the first long skirt has a slit along the connecting portion. 6. The cathode ray tube according to claim 4, wherein a connecting portion between the connecting plate and the first skirt has a slit along the connecting portion. 7. The cathode ray tube according to claim 1, wherein the internal magnetic shield is made of a material having a higher magnetic permeability than the frame. 8. The cathode ray tube according to claim 1, further comprising an electron shield plate protruding from the frame toward a tube axis along a short side of the frame.