JP2002150964A - Internal magnetic shield and cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent landing mistakes of the electron beams caused by the tube axis magnetic field by reducing a magnetic field By, that is emitted to the tube axis side from the edge of the long sides side frame, where an internal magnetic shield is installed. SOLUTION: In the internal magnetic shield 100 for the cathode-ray tube, that is formed by joining a pair of long sides side plates 101a, 101b of a nearly trapezoidal form arranged facing opposite to each other and a pair of short sides side plates 102a, 102b of a nearly trapezoidal form arranged opposed to each other forming a part of a nearly quardrangular pyramid face, slits 111, 112 are formed along the lower side bottom side of the long sides side plate. The slits 111, 112 function as magnetic resistance with respect to the tube magnetic field, which passes in the internal magnetic shield, and reduce generation of magnetic field By. As a result, landing mistakes due to the tube axis magnetic field is suppressed and occurrence of color slippage is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal magnetic shield provided inside a cathode ray tube for reducing a displacement of a landing position of an electron beam due to an external magnetic field such as terrestrial magnetism, and a cathode ray tube having the same.

[0002]

FIG. 17 shows a conventional color cathode ray tube 800.
FIG. 3 is a vertical cross-sectional view passing through the tube axis of FIG. For convenience of the following description, as shown, a horizontal axis passing through the tube axis and perpendicular to the tube axis is the X axis, a vertical axis passing through the tube axis and perpendicular to the tube axis is the Y axis, An XYZ-three-dimensional orthogonal coordinate system with the tube axis as the Z axis is set.

[0003] A front panel 801 and a funnel 802 are integrated to form an envelope 803. Front panel 80
A phosphor screen 804 having a substantially rectangular shape is formed on the inner surface of the light emitting element 1. A color selection electrode (for example, a shadow mask) spaced apart from and opposed to the phosphor screen 804
805 is mounted on the frame 810 so as to be stretched.
The frame 810 is configured such that a leaf spring-like elastic support (not shown) installed on the outer peripheral surface thereof is hooked on a panel pin (not shown) implanted on the inner surface of the front panel 801.
It is held by a front panel 801. Funnel 802
The electron gun 806 is built in the neck portion of. A deflection yoke 808 is provided on the outer peripheral surface of the funnel 802, so that an electron beam 807 from the electron gun 806 is provided.
Scans on the phosphor screen 804 while being deflected in the horizontal and vertical directions.

An electron shield plate 820 is provided on the surface of the frame 810 on the side of the electron gun 806.
The end of the electron shield plate 820 on the tube axis side projects from the inner side surface of the frame 810 toward the tube axis, and
It is slightly bent to the electron gun 806 side. When the trajectory of the electron beam 807 shifts outward from the original trajectory for some reason, the electron shield plate 820 reflects the electron beam 807 on the frame 810 and reflects it toward the color selection electrode 805 to display a display image. Prevent disturbing.

When an external magnetic field such as terrestrial magnetism acts on the cathode ray tube, the trajectory of the electron beam 807 changes, and the electron beam 807 does not reach a desired position on the phosphor screen 804, so that a so-called “mislanding” occurs. 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 degraded.
The direction of the external magnetic field depends on the installation direction of the cathode ray tube,
In addition, the size 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 807 is shielded from an 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 to. For such a purpose, an internal magnetic shield 830 is provided between the frame 810 and the deflection yoke 808.

FIG. 18 is an exploded perspective view showing the structure of a color selection structure including a frame 810, an electron shield plate 820, and an internal magnetic shield 830.

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 has a hollow triangular prism shape, extend one side surface toward the phosphor screen side, and attach a color selection electrode 8 to the end thereof.
05 is spanned. Short side frames 812a, 812b
Is formed by bending a metal plate so that its cross section becomes substantially U-shaped. A pair of long side frames 811a and 811b and a pair of short side frames 812a and 812b are combined in a substantially rectangular shape, and a joint is welded to form a frame 810.

The electron shield plate 820 is formed by joining a pair of long side shield plates 821a and 821b and a pair of short side shield plates 822a and 822b in a substantially rectangular shape.

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, 833b bent to be substantially parallel to the XY plane are provided on the sides (lower bottom sides) of the long side plates 831a, 831b on the frame 810 side.
Are formed. In addition, short side plates 832a, 832b
The short side skirts 834a, 834a
34b (short side skirt 834b is not shown).

On the long side frames 811a and 811b of the frame 810 configured as described above, the long side shield plates 821a and 821b of the electron shield plate 820 are provided.
And the long side skirt 833a of the internal magnetic shield 830,
833b are sequentially superimposed on each other,
5,825,835. At this time, the short side skirts 834a, 834b of the internal magnetic shield 830
Are the gap between the short side shield plate 822a and the short side frame 812a, and the short side shield plate 822b and the short side frame 8
12b.

As described above, a color selection structure as shown in FIG. 19 is formed.

Regarding the internal magnetic shield, various methods have been proposed for converting an external magnetic field such as terrestrial magnetism into a magnetic field in a direction that does not cause color shift or the like. For example, by providing a V-shaped notch in the pair of short side plates 832a and 832b of the internal magnetic shield 830, mislanding due to an external magnetic field (hereinafter, referred to as "tube axis magnetic field") in the direction of the tube axis (Z axis) is provided. It is described in JP-A-53-15061 that it can be prevented. Also, a pair of long side plates 831a, 83
1b is provided with elongated slits 833, 837 along the trajectory direction of the electron beam (that is, so as to connect the upper base and the lower base of the long side plate having a substantially trapezoidal shape). Japanese Patent Application Laid-Open No. Sho 58-158 discloses that mislanding due to a magnetic field (hereinafter referred to as "transverse magnetic field") can be prevented.
No. 178945.

[0013]

With the development of computer technology and the like, high-definition image display is required, and the display pixels are becoming finer and finer. For this reason, the allowable range for the mislanding of the electron beam becomes strict, and in the configuration of the conventional internal magnetic shield, non-negligible color misregistration due to the mislanding of the electron beam is beginning to occur.

The present inventors have conducted various studies on factors that cause electron beam mislanding, and have found that there is a new problem factor. Hereinafter, this will be described.

FIG. 20 shows an E parallel to the YZ plane of FIG.
It is sectional drawing seen from the arrow direction in -E line. In FIG. 20, a case is considered in which a tube axis magnetic field running downward from the top of the paper is applied. The tube axis magnetic field is controlled by the internal magnetic shield 8.
The long side skirt 8 is absorbed by the long side
It flows to 33a. Then, the electron shield plate 82
0 enters the long side shield plate 821a, and a part thereof enters the long side frame 811a. At this time, a part of the magnetic field gushes from the long side shield plate 821a and the end of the long side frame 811a near the tube axis, and a magnetic field By in the Y-axis direction is generated. Here, the description has been given using the cross section of the long side plate 831a side, but similarly, the magnetic field By in the Y axis direction from the long side shield plate 821b and the long side frame 811b toward the tube axis is also applied to the long side plate 831b side. appear. Such a magnetic field B
Since y displaces the trajectory of the electron beam in the X-axis direction, a color shift occurs.

According to the present invention, the long side shield plates 821a, 82
An internal magnetic shield and a cathode ray tube that can prevent the generation of a mislanding of an electron beam due to the tube axis magnetic field by reducing the generation of a magnetic field By ejected toward the tube axis side from the Y axis direction ends of the 1b and the long side frames 811a and 811b. The purpose is to provide.

[0017]

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

The internal magnetic shield according to the present invention comprises a pair of substantially trapezoidal long-side plates disposed to face each other and a pair of substantially trapezoidal short-side plates disposed to face each other. An internal magnetic shield for a cathode ray tube combined to form a part of a surface, wherein a slit or a notch is formed in the long side plate so as to cut along or cut the lower bottom of the long side plate. Is formed.

Here, in the present invention, the "lower bottom side" means the longer side of a pair of parallel sides of the long side plate having a substantially trapezoidal shape. Note that the other shorter side is referred to as “upper bottom side”.

Further, the cathode ray tube of the present invention comprises: an envelope comprising a front panel and a funnel; a phosphor screen formed on an inner surface of the front panel; and a color selector disposed opposite to the phosphor screen. An electrode, a 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, wherein the internal magnetic shield is the internal magnetic shield of the present invention.

According to the above-described internal magnetic shield and cathode ray tube of the present invention, the slit or the notch acts as a magnetic resistance to the tube axis magnetic field passing through the internal magnetic shield, and the long side shield plate and the long side frame are provided. , The generation of the magnetic field By spouting from the end in the Y-axis direction toward the tube axis can be reduced. As a result, mislanding of the electron beam due to the tube axis magnetic field is suppressed, and the occurrence of color shift can be prevented.

[0022]

(Embodiment 1) The configuration of a color cathode ray tube according to Embodiment 1 of the present invention is the same as that of the color cathode ray tube 800 shown in FIG. 17 except for the internal magnetic shield. Therefore, detailed description of the configuration other than the internal magnetic shield is omitted.

FIG. 1 is an exploded perspective view showing the structure of a color selection structure used in the color cathode ray tube according to the first embodiment.

The frame 810 and the electron shield plate 820 are the same as those shown in FIG. 18, and the same members as those in FIG.

The internal magnetic shield 100 has a pair of substantially trapezoidal opposed long side plates 101a, 101b and a pair of substantially trapezoidal opposed short side plates 102a, 102b. Are formed so as to form a part of each other. Long side skirts 103a, 103b bent to be substantially parallel to the XY plane are provided on the sides (lower bottom sides) of the long side plates 101a, 101b on the frame 810 side.
Are formed. Also, the short side plates 102a, 102b
Of the short side skirt 104a, 1
04b (short side skirt 104b is not shown).

In this embodiment, the long side plates 101a, 101
01b, elongated first slits 111 and 112 having a longitudinal direction in the X-axis direction are formed. First slit 11
Reference numerals 1 and 112 denote bent portions 109 which are boundaries between the long side plates 101a and 101b and the long skirts 103a and 103b.
One end of the opening (which corresponds to the lower base of the substantially trapezoidal long side plates 101a and 101b) is opened at a predetermined height on the long side plates 101a and 101b. First
The center point of the slit 111 in the X-axis direction coincides with the middle point of the bent portion (lower bottom side) 109, and the first slits 1 on both sides thereof
Numeral 12 is formed at a position distant from the midpoint of the bent portion (lower bottom side) 109 and symmetrically with respect to the midpoint.

Further, a pair of long side plates 101a, 101b
In addition, elongated second slits 106 and 107 are formed along the trajectory direction of the electron beam (that is, so as to connect the upper base and the lower base of the substantially trapezoidal long side plate). The second slit 106 is formed in a substantially rectangular shape at the center position in the X-axis direction, and the second slits 107 on both sides thereof are formed in a substantially trapezoidal shape and symmetrically at positions symmetric with respect to the slit 106.

The internal magnetic shield 100 and the electron shield plate 820 are manufactured by using a material having high magnetic permeability (for example, soft iron) by a known method such as pressing.

The internal magnetic shield 100 is mounted on the frame 810 via the electron shield plate 820 as in the prior art, and the joints 105, 825, 8
Spot welding is performed at 15 to obtain the color sorting structure shown in FIG.

Next, the first slit 11 of the present embodiment
The operation of 1,112 will be described.

FIG. 3 is a sectional view taken on line A--A of FIG.
It is sectional drawing seen from the arrow direction in a line. In FIG.
Consider a case in which a tube axis magnetic field running downward from the top of the paper is applied. The tube axis magnetic field is absorbed by the long side plate 101a of the internal magnetic shield 100, and the long side skirt 103a
Try to flow to the side. However, in the present embodiment, the first slit 111 exists between the long side plate 101a and the long skirt 103a, and this serves as a resistance to prevent passage of the tube axis magnetic field. As a result, Y ejected from the end near the pipe axis of the long side shield plate 821a and the long side frame 811a.
The generation of the magnetic field By in the axial direction can be weakened as compared with the case of FIG. 20, and the displacement of the landing position of the electron beam can be reduced. The first slit 112 has a similar function. Similarly, on the long side plate 101b side, the first slits 111 and 112 can also weaken the generation of the magnetic field By in the Y-axis direction spouting from the end near the tube axis of the long side shield plate 821b and the long side frame 811b. it can.

The above operation will be described in more detail with reference to specific examples.

A color selection structure having a structure shown in FIGS. 1 to 3 and having a diagonal size of 38 inches for a color cathode ray tube was manufactured. The various dimensions are as follows. In FIG. 4 showing a side view of the internal magnetic shield 100 viewed from the long side plate 101a side, the length W1 in the X-axis direction of the first slit 111 at the center is 160 mm, and the height H1 in the Z-axis direction is 3 m.
m, the length W2 of the first slits 112 on both sides in the X-axis direction W2 = 8
0 mm, its height in the Z-axis direction H2 = 3 mm, and the long side plate 10
The length L of the lower bottom side of 1a is 600 mm, and the long side plate 101 is provided.
The length D1 from the X-axis direction end to the end closer to the first slit 112 was 60 mm, and the distance D2 between the first slit 111 and the first slit 112 was 80 mm (Example 1).

Further, except that the first slits 112 on both sides are not formed and only the first slit 111 at the center is formed in the same position and the same size as the above, the color sorting structure is formed in the same manner as in the first embodiment. It was manufactured (Example 2).

A color selection structure was manufactured in the same manner as in Example 1 except that the first slits 111 and 112 were not formed (Comparative Example 1).

A tube axis magnetic field is applied to the color-selecting structures of Examples 1 and 2 and Comparative Example 1, and a magnetic field in the Y-axis direction ejected from the end of the long side shield plate 821a and the long side frame 811a near the tube axis. By (see FIGS. 3 and 20) was measured along the X-axis direction.

The results are shown in FIGS.

In FIG. 5, the horizontal axis represents the position in the X-axis direction when the midpoint of the lower base is X = 0 mm. The vertical axis indicates the magnetic flux density of the Y-axis direction magnetic field By at each position in the X-axis direction. The color selection structure is formed symmetrically about the position of X = 0, and the measurement result of the magnetic field By is also symmetrical about the position of X = 0. is there. The region I shown in the upper part of FIG.
, A region where the first slit 111 at the center is formed, and a region II indicates a region where the one slit 112 on both sides of the first slit 111 is formed.

FIGS. 6, 7 and 8 visually show the generation state of the magnetic field By in the Y-axis direction in Example 1, Example 2, and Comparative Example 1, respectively, according to the results shown in FIG. FIG. The length of the arrow of the magnetic field By shown in FIGS. 6 to 8 corresponds to the strength (magnetic flux density) of the magnetic field. In FIG. 7, reference numeral 100 ′ denotes an internal magnetic shield according to the second embodiment in which the first slit 111 is provided only at the center in the long side direction.

In Comparative Example 1 in which the first slits 111 and 112 were not provided, as shown in FIGS.
y rapidly increases from the end in the long side direction (X = ± 300 mm point) to the center, and the X value is −150.
It is maximum and constant in the range of +150 mm.

On the other hand, in the second embodiment in which the first slit 111 is provided only in the central portion in the long side direction, as shown in FIGS. It increases rapidly from the end in the direction (the point of X = ± 300 mm) to the center. However, the magnetic field By is maximized at a point where X is approximately ± 150 mm, and drops sharply toward the center. The decrease in the magnetic field By at the central portion in the long side direction is caused by the first slit 111. That is, the first slit 111 acts as a magnetic resistance with respect to the tube axis magnetic field, and reduces the amount of the magnetic field By that is blown out at the central portion in the long side direction.

Further, the first slit 11 at the central portion in the long side direction
In the first embodiment in which the first slits 112 are provided on both sides in addition to the magnetic field B, as shown in FIGS.
The maximum value of y is reduced to about half of the maximum value of the magnetic field By of the second embodiment, and the intensity of the magnetic field By at the central portion is also significantly lower than that of the second embodiment. As described above, in the first embodiment, by providing three first slits in the long-side direction, the amount of the magnetic field By blowout can be reduced over the entire width in the long-side direction, and the width of the magnetic field By in the width direction can be reduced. Variations in strength can also be reduced.

As is apparent from the above description, by providing an elongated slit having the long side direction as the longitudinal direction near the connection portion of the long side plate of the internal magnetic shield with the frame,
Tube axis magnetic fields can be prevented from passing through the inner magnetic shield. Therefore, the long side shield plates 821a, 8
It is possible to reduce the Y-axis direction magnetic field By ejected from the tube axis side end of the long side frames 811a and 811b. As a result, mislanding of the electron beam can be reduced, and the occurrence of color shift can be suppressed.

The position at which the first slit is formed in the X-axis direction is not limited to the above-described embodiment as long as the above-described effects are obtained. For example, in the first embodiment, the first portion at the center in the long side direction is used.
Without providing the slit 111, the first slit 112 on both sides
Only one can be provided. Alternatively, the first slit 1
11 and the first slit 112 can be formed continuously. However, since the slit long in the long side direction lowers the mechanical strength of the internal magnetic shield and causes vibration, the ratio of the first slit to the lower base in the long side direction (in the example of FIG. 4, ( W2 + W1 + W2) / L)
Is preferably ３ or less, more preferably １ ／ or less,
It is preferable that the first slit be divided into a plurality of parts in the long side direction as necessary so that the distribution of the magnetic field By is optimized within a range that satisfies this.

Further, it is not preferable to form the first slit up to the lower bottom end in order to secure the joint portion 105 for fixing the internal magnetic shield 100 to the frame 810 and the fixing strength. That is, in FIG. 4, the distance D from the lower bottom end to the end of the first slit is closer to the end.
1 is preferably 20 mm or more, more preferably 40 mm or more.

In any case, the first slit may be provided symmetrically at a position symmetrical with respect to the middle point (point X = 0) of the lower bottom side, so that the amount of color misregistration on the left and right sides of the screen can be reduced. It is preferable from the viewpoint of ensuring balance.

The opening height (H1, H2 in FIG. 4) of the first slit in the tube axis direction needs to be a size necessary to effectively prevent passage of the tube axis magnetic field, and is 3 mm or more. It is preferred that However, if the opening height is too large, the electron beam will pass through to generate halation, or the mechanical strength of the internal magnetic shield will decrease. Therefore, it is preferable that the opening height be about 5 mm or less.

When the second slits 106 and 107 are provided along the trajectory direction of the electron beam as in the above-described example, it is not preferable to form the first slits 111 and 112 by connecting them. In addition, it is preferable to provide the first slit avoiding the extension of the second slit as much as possible. In either case, the mechanical strength of the internal magnetic shield is ensured.

In the above example, the first slit is formed by the long side skirts 103a and 103b and the long side plates 101a and 1a.
The first slit is provided on the long side plate along the bent portion 109 which is a boundary with the first slit, that is, such that one end of the opening of the first slit coincides with the bent portion 109. When the first slit and the bent portion 1 are provided separately from the bent portion 109 toward the electron gun side.
Since the tube axis magnetic field wraps around the area between the first slit and the first slit, the effect of the first slit as the magnetic resistance is reduced.

Next, the second slits 106 and 107 will be described.

The second slit is provided along the trajectory of the electron beam, and acts as a magnetic resistance to a transverse magnetic field. Therefore, the opening width in the X-axis direction needs to be a size necessary for effectively blocking the passage of the transverse magnetic field, and is preferably 3 mm or more. However, if the opening width is too large, the shielding effect against the tube axis magnetic field is reduced, and the mechanical strength of the internal magnetic shield is reduced. Therefore, it is preferable that the opening width be about 20 mm or less.

The number of the second slits formed on one of the long side plates is not limited to three as described above, and can be changed as appropriate according to the size of the cathode ray tube. The greater the number of slits, the better the blocking effect of the transverse magnetic field, but the lower the shielding effect against the tube axis magnetic field and the mechanical strength. Generally, 3 to 9 are preferable. The arrangement and shape of the second slit are preferably symmetric with respect to a straight line parallel to the YZ plane passing through the point of X = 0. By changing the position of each second slit in the X-axis direction, the displacement amount and displacement direction of the landing position of the electron beam due to the tube axis magnetic field and the transverse magnetic field can be adjusted.

(Embodiment 2) Embodiment 2 is the same as Embodiment 1 except for the first slit of the internal magnetic shield.

FIG. 9 is a perspective view showing a schematic configuration of the internal magnetic shield 200 according to the second embodiment. In FIG. 9, components having the same functions as those of the internal magnetic shield 100 according to the first embodiment are denoted by the same reference numerals.

The first slits 211 and 212 of the internal magnetic shield 200 of the present embodiment are different from the first slits 111 and 112 of the first embodiment, and the long side plates 101a and 1
01b to the long side skirt 103 beyond the bent portion 109
a and 103b.

The internal magnetic shield 200 according to the second embodiment
In the same manner as in the first embodiment, the electron shield plate 8
It is mounted on the frame 810 via the reference numeral 20 (see FIG. 1) to form a color selection structure.

FIG. 10 is a cross-sectional view when the color selection structure using the internal magnetic shield 200 according to the second embodiment is cut along a plane corresponding to the line BB parallel to the YZ plane in FIG. is there. In FIG. 10, consider a case where a tube axis magnetic field running downward from the top of the paper is applied. As in the case of the first embodiment, the tube axis magnetic field is absorbed by the long side plate 101a of the internal magnetic shield 200 and tends to flow toward the long side skirt 103a, but the long side plate 101a and the long side skirt 103a And the first slit 211 between them acts as a resistance to prevent passage of the tube axis magnetic field. As a result, the long side shield plate 82
The generation of the magnetic field By in the Y-axis direction ejected from the end near the tube axis of the long frame 1a and the long side frame 811a can be weakened as compared with the case of FIG. it can. First slit 21
2 has a similar effect. Similarly, on the long side plate 101b side, the first slits 211 and 212 can also weaken the generation of the magnetic field By in the Y-axis direction spouting from the end near the tube axis of the long side shield plate 821b and the long side frame 811b. it can.

The formation positions of the first slits 211 and 212 in the X-axis direction and the length in the X-axis direction, the opening height from the bent portion 109 in the tube axis (Z-axis) direction, the second slits 106 and 107
The description in Embodiment 1 can be similarly applied to the relationship.

As described above, even if the first slit is provided in the long side plate so as to cut the bent portion 109 (to straddle the bent portion 109), the same effect as in the first embodiment can be obtained.

(Embodiment 3) Embodiment 3 is the same as Embodiment 2 except for the long side skirt of the internal magnetic shield.

FIG. 11 is a perspective view showing a schematic configuration of an internal magnetic shield 300 according to the third embodiment. 11, components having the same functions as those of the internal magnetic shield 200 according to the second embodiment are denoted by the same reference numerals.

Internal Magnetic Shield 300 of Third Embodiment
Long side skirts 320a and 320b are connected to the long side side plates 101a and 101b via the bent portion 109, and the long side first skirts 321a and 321b and the long side first skirt 3
Long side second skirt 322 connected to 21a, 321b
a, 322b. Long side first skirt 321a,
321b is substantially parallel to the XY plane, and has a second long side.
The skirts 322a and 322b are substantially parallel to the XZ plane.

As in the second embodiment, the first slits 211 and 212 are formed so as to extend from the long side plates 101a and 101b to the first long skirts 321a and 321b beyond the bent portion 109.

Internal Magnetic Shield 300 of Third Embodiment
Is mounted on the frame 810 via the electron shield plate 820 as in the first and second embodiments (see FIG. 1) to form a color selection structure.

FIG. 12 is a cross-sectional view when the color selection structure using the internal magnetic shield 300 according to the third embodiment is cut along a plane corresponding to the line CC parallel to the YZ plane in FIG. is there.

In FIG. 12, it is assumed that a tube axis magnetic field running downward from the top of the paper is applied. Similarly to the first and second embodiments, the tube axis magnetic field is absorbed by the long side plate 101a of the internal magnetic shield 300 and tends to flow toward the long side skirt 320a. The first slit 211 between the skirt 320a acts as a resistance to prevent passage of the tube axis magnetic field. As a result, the generation of the magnetic field By in the Y-axis direction spouting from the end near the tube axis of the long side shield plate 821a and the long side frame 811a is shown in FIG.
This can be weakened as compared with the case of 0, and the shift amount of the landing position of the electron beam can be reduced. First
The slit 112 has a similar function. Similarly, on the long side plate 101b side, the first slits 211 and 211 are also provided.
12, the long side shield plate 821b and the long side frame 8
Magnetic field B in the Y-axis direction ejected from the end near the tube axis of 11b
The occurrence of y can be reduced.

In the present embodiment, as shown in FIG. 12, the first long side skirt 321a is
a, the second side skirt 322a is in contact with the outer side surface of the long side frame plate 811a. Although not shown, the long side first skirt 321b and the long side second skirt 322b facing each other have the same structure. By providing the long side second skirts 322a and 322b so as to be in contact with the outer side surfaces of the long side frames 811a and 811b, the magnetic flux of the tube axis magnetic field is reduced by the long side second skirt 322.
a, 322b via the long side frames 811a, 811b
Flows to the outer side surface of the long side shield plate 821a, 8
It is possible to further weaken the magnetic field By in the Y-axis direction ejected from the ends of the 21b and the long side frames 811a, 811b near the tube axis.

The positions where the first slits 211 and 212 are formed in the X-axis direction, the length in the X-axis direction, the opening height from the bent portion 109 in the tube axis (Z-axis) direction, the second slits 106 and 107
The description in Embodiment 1 can be similarly applied to the relationship.

Although the first slits 211 and 212 of the internal magnetic shield 300 described above have the same configuration as in the second embodiment, the first slits 111 and 112 similar to those in the first embodiment are formed instead. You may.

(Embodiment 4) Embodiment 4 is the same as Embodiment 1 except for the first slit of the internal magnetic shield.

FIG. 13 is a perspective view showing a schematic configuration of an internal magnetic shield 400 according to the fourth embodiment. 13, components having the same functions as those of the internal magnetic shield 100 according to the first embodiment are denoted by the same reference numerals.

In the internal magnetic shield 400 of the present embodiment, instead of the first slits 111 and 112 of the first embodiment, the long side skirts 103a and 103b extend from the free ends to the long side plates beyond the bent portion 109. Substantially rectangular notches 411 and 412 extending to 101a and 101b are formed.

Internal Magnetic Shield 400 of Fourth Embodiment
In the same manner as in the first embodiment, the electron shield plate 8
It is mounted on the frame 810 via the reference numeral 20 (see FIG. 1) to form a color selection structure.

FIG. 14 is a cross-sectional view when the color selection structure using the internal magnetic shield 400 according to the fourth embodiment is cut along a plane corresponding to the line DD parallel to the YZ plane in FIG. is there. In FIG. 14, consider a case where a tube axis magnetic field running downward from the top of the paper is applied. Similarly to the first embodiment, the tube axis magnetic field is absorbed by the long side plate 101a of the internal magnetic shield 400 and tends to flow toward the long skirt 103a, but the notch 411 formed in the long side plate 101a. Become resistance and hinder passage of the tube axis magnetic field. As a result, the long side shield plate 821a and the long side frame 811
The generation of the magnetic field By in the Y-axis direction ejected from the end near the tube axis a can be weakened as compared with the case of FIG. 20, and the shift amount of the landing position of the electron beam can be reduced. The notch 412 has a similar function. Also,
The notch 41 is similarly formed on the long side plate 101b.
1, 412, it is possible to reduce the generation of the magnetic field By in the Y-axis direction ejected from the end of the long side shield plate 821b and the long side frame 811b near the tube axis.

The positions where the notches 411 and 412 are formed in the X-axis direction, the length in the X-axis direction, and the tube axis (Z
The description in the first embodiment can be similarly applied to the relationship between the opening height in the (axial) direction and the second slits 106 and 107.

The long side skirt of the above-described internal magnetic shield 400 is extended at its free end and bent so as to be parallel to the XZ plane.
May be formed in the same shape as the long side skirts 320a and 320b.

(Embodiment 5) Embodiment 5 is the same as Embodiment 1 except for the second slit of the internal magnetic shield.

FIG. 15 is a perspective view showing a schematic configuration of an internal magnetic shield 500 according to the fifth embodiment. 15, components having the same functions as those of the internal magnetic shield 100 according to the first embodiment are denoted by the same reference numerals.

The second slits 506 and 507 of the internal magnetic shield 500 according to the present embodiment are different from the second slits 106 and 107 according to the first embodiment in that the long side plates 101a and 1
It is formed so as to reach the end (upper bottom side) of the electron gun 01b on the electron gun side (upward in FIG. 15).

According to such a configuration, the magnetoresistance effect of the second slit on the transverse magnetic field is exerted more, and the mislanding of the electron beam due to the transverse magnetic field can be further reduced.

It is to be noted that not all the second slits are formed so as to reach the upper bottom side as described above, but only a part thereof is formed as in the fifth embodiment, and the others are the same as those in the first embodiment. It may be formed as follows.

The second slit of the present embodiment can be similarly applied to the internal magnetic shield of the above-described second to fourth embodiments.

(Embodiment 6) FIG. 16 shows Embodiment 6 of the present invention.
FIG. 2 is a perspective view showing a schematic configuration of an internal magnetic shield 600 of FIG. 16, components having the same functions as those of the internal magnetic shield 500 according to the fifth embodiment are denoted by the same reference numerals.

Internal Magnetic Shield 600 of Sixth Embodiment
In the second embodiment, second slits 506 and 507 are formed in the long side plates 101a and 101b in the same manner as in the fifth embodiment, and a non-magnetic material (for example, stainless steel SU) is formed along the upper bottom.
S304) are attached (welded) to the holding plates 601a and 601b.

With such a configuration, the long side plate 101
Since the upper bottom sides of the a and 101b divided by the second slits 506 and 507 are connected by the holding plates 601a and 601b, the mechanical strength of the internal magnetic shield 600 is improved, and harmful vibration can be prevented. Tube assembly work is also facilitated.

Further, since the holding plates 601a and 601b are attached along the upper bottom sides of the long side plates 101a and 101b, the mechanical strength and the mechanical strength are lower than when the holding plates 601a and 601b are attached at a position between the upper bottom side and the lower bottom side. Great improvement effect on vibration. Further, since the accuracy of the shape of the internal magnetic shield is easily maintained, it is possible to reduce the variation in the raster distortion and the deviation of the landing position of the electron beam due to the external magnetic field among the cathode ray tubes.

The short side plates 102a and 102b of the internal magnetic shield of the present invention described in each of the above embodiments may be provided with V-shaped notches from the electron gun side end toward the frame side. .

In the above description, the electron shield plate 82 is provided between the frame 810 and the internal magnetic shield.
Although the cathode ray tube having 0 is shown, the present invention can be applied to a cathode ray tube having no electron shield plate 820, and the same effects as described above can be obtained. However, when the electron shield plate 820 is provided, the blowing amount of the Y-axis direction magnetic field By shown in FIG. 20 increases, so that the effect of the present invention is more remarkably exhibited in the cathode ray tube provided with the electron shield plate 820. .

In the present invention, the material of the frame 810 is not particularly limited. For example, an iron-based material, an invar material, or the like can be used. When the invar material is used, the blowing amount of the magnetic field By in the Y-axis direction shown in FIG. Therefore, the effect of the present invention is more remarkably exhibited in the cathode ray tube provided with the frame 810 made of Invar material.

[0090]

As described above, according to the present invention, the slit formed along the lower bottom of the long side plate acts as a magnetic resistance to the tube axial magnetic field passing through the internal magnetic shield, The generation of the magnetic field By spouting toward the tube axis side from the Y-axis end of the long side shield plate and the long side frame can be reduced. As a result, mislanding of the electron beam due to the tube axis magnetic field is suppressed, and the occurrence of color shift can be prevented.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of a color selection structure used in a color cathode ray tube according to a first embodiment of the present invention.

FIG. 2 is an overall perspective view of a color selection structure used in the color cathode ray tube according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along a line AA in FIG.

FIG. 4 is a side view of the internal magnetic shield according to the first embodiment of the present invention as viewed from a long-side plate;

FIG. 5 shows the color sorting structures of Examples 1 and 2 and Comparative Example 1.
FIG. 4 is a diagram illustrating a magnetic flux density distribution of a Y-axis direction magnetic field By.

FIG. 6 is an exploded perspective view illustrating a generation state of a Y-axis direction magnetic field By in the first embodiment.

FIG. 7 is an exploded perspective view illustrating a generation state of a Y-axis direction magnetic field By of the second embodiment.

FIG. 8 is an exploded perspective view showing a generation state of a Y-axis direction magnetic field By in Comparative Example 1.

FIG. 9 is a perspective view showing a schematic configuration of an internal magnetic shield according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view of a color selection structure according to a second embodiment of the present invention, taken along a plane that passes through a first slit and is parallel to a YZ plane.

FIG. 11 is a perspective view showing a schematic configuration of an internal magnetic shield according to a third embodiment of the present invention.

FIG. 12 is a cross-sectional view of a color selection structure according to a third embodiment of the present invention, taken along a plane that passes through a second slit and is parallel to a YZ plane.

FIG. 13 is a perspective view showing a schematic configuration of an internal magnetic shield according to a fourth embodiment of the present invention.

FIG. 14 is a cross-sectional view of a color sorting structure according to a fourth embodiment of the present invention, taken along a plane that passes through a notch and is parallel to a YZ plane.

FIG. 15 is a perspective view showing a schematic configuration of an internal magnetic shield according to a fifth embodiment of the present invention.

FIG. 16 is a perspective view showing a schematic configuration of an internal magnetic shield according to a sixth embodiment of the present invention.

FIG. 17 is a sectional view showing a schematic configuration of a cathode ray tube.

FIG. 18 is an exploded perspective view showing a configuration of a color selection structure used in a conventional color cathode ray tube.

FIG. 19 is an overall perspective view of a color selection structure used in a conventional color cathode ray tube.

20 is a cross-sectional view as seen from the direction of the arrows along the line EE in FIG. 19;

[Explanation of symbols]

 100, 100 'Internal magnetic shields 101a, 101b Long side plates 102a, 102b Short side plates 103a, 103b Long side skirts 104a, 104b Short side skirts 105 Joints 106, 107 Second slit 109 Bends 111, 112 First slit 200 Internal magnetic shield 211, 212 First slit 300 Internal magnetic shield 320a, 320b Long side skirt 321a, 321b Long side first skirt 322a, 322b Long side second skirt 400 Internal magnetic shield 411, 412 Notch 500 Internal magnetic shield 506, 507 Second slit 600 Internal magnetic shield 601a, 601b Holding plate 800 Color cathode ray tube 801 Front panel 802 Funnel 803 Enclosure 804 Phosphor screen 805 Color selection electrode 06 Electron gun 807 Electron beam 808 Deflection yoke 810 Frame 811a, 811b Long side frame 812a, 812b Short side frame 815 Joint 820 Electron shield plates 821a, 821b Long side shield plate 822a, 822b Short side shield plate 825 Joint magnetism 830 Shield 831a, 831b Long-side plate 832a, 832b Short-side plate 833a, 833b Long-side skirt 834a, 834b Short-side skirt 835 Joint 833, 837 Slit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Saito 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Corporation Incorporated (72) Inventor Hideo Iguchi 1-1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics (72) Inventor Hidekazu Kojima 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. (72) Inventor Takayuki Yonezawa 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. ( 72) Inventor Tomohisa Mikami 1-1, Sachimachi, Takatsuki-shi, Osaka, Japan Matsushita Electronics Industrial Co., Ltd. (72) Inventor Yoko Henan 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. ) 5C031 CC02 CC05

Claims (12)

[Claims] A pair of substantially trapezoidal long-side plates disposed opposite to each other and a pair of substantially trapezoidal short-side plates disposed opposite each other to form a part of a substantially quadrangular pyramid surface. An internal magnetic shield for a cathode ray tube, which is combined as described above, wherein a slit or a notch is formed in the long side plate so as to cut along or along the lower bottom of the long side plate. Features internal magnetic shield. 2. The internal magnetic shield according to claim 1, wherein the slit or the notch is provided at a center of the lower bottom side. 3. The internal magnetic shield according to claim 1, wherein the slit or notch is provided between a center and an end of the lower bottom side. 4. A long-side skirt is connected to the lower bottom side of the long-side side plate, and the slit extends along or across a boundary between the long-side side plate and the long-side skirt. The internal magnetic shield according to claim 1, wherein the internal magnetic shield is formed. 5. A long side skirt is connected to the lower bottom side of the long side plate, and the notch is formed to extend from the long side skirt over the lower bottom side to the long side portion. 2. The internal magnetic shield according to claim 1, wherein the internal magnetic shield is provided. 6. The internal magnetic shield according to claim 1, wherein a distance from an end of the lower bottom side of the long side plate to an end of the slit or notch on the end side is 20 mm or more. 7. The internal magnetic shield according to claim 1, wherein a second slit having a longitudinal direction connecting the lower base and the upper base is formed in the long side plate. 8. The internal magnetic shield according to claim 7, wherein the second slit reaches the upper bottom side. 9. The internal magnetic shield according to claim 8, wherein a holding plate made of a non-magnetic material is provided for connecting the upper base divided by the second slit. 10. The second slit is not connected to the slit or the notch formed along or to cut the lower bottom of the long side plate.
Internal magnetic shield as described in. 11. 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. Holding the frame,
A cathode ray tube comprising: an electron gun installed in the funnel; and an internal magnetic shield held by the frame and installed on the electron gun side with respect to the color selection electrode, wherein the internal magnetic shield is provided. A cathode ray tube, which is the internal magnetic shield according to any one of claims 1 to 10. 12. The cathode ray tube according to claim 10, wherein the internal magnetic shield is held on the frame via an electron shield plate.