JPH08167386A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE: To efficiently reduce the mislanding relative to the external magnetic field by arranging recttangular parts extended in the direction of an electron gun at prescribed intervals in the direction of the side of a frame, and reducing the length of each rectangular part from the vicinity of the center of the frame side toward each end thereof. CONSTITUTION: A shadow mask 4 is provided on the inner side of a panel to which a fluorescent surface is attached, and this shadow mask 4 is supported by a frame 5. A magnetic shielding member 12 is provided so as to hold the upper and lower sides of the electron beam to be reflected from an electrom gun 2. A color cathode-ray tube(CRT) contains a funnel and a neck. The magnetic shielding part is integratedly formed approximately is parallel to the inner wall of the funnel, rectangular parts extended in the direction of an electron gun from the frame are arranged in a prescribed space in the direction of the frame side, and the length of the rectangular parts is reduced from the vicinity of the center of the frame side toward each and thereof. The mislanding is efficiently reduced relative to the external magnetic field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and more particularly to a magnetic shield mounted on the color cathode ray tube in order to prevent troubles such as color shift due to shake of an electron beam due to an external magnetic field such as earth magnetism. It is about.

[0002]

2. Description of the Related Art In a three-electron-beam type color cathode ray tube having a shadow mask built-in, the orbit of the electron beam sways due to the influence of an external magnetic field such as the earth's magnetism. It is known that undesired phosphors are caused to emit light, resulting in unfavorable results such as color shift. In order to remove the influence of such an external magnetic field, a magnetic mask is attached from a shadow mask along the funnel.

Next, an example of such a color cathode ray tube will be described with reference to FIG. FIG. 17 is a sectional view of a conventional color cathode ray tube as described above. In the figure, reference numeral 1 denotes a tubular body, which is composed of a neck 1a, a funnel 1b, and a panel 1c. An electron gun 2 is arranged in the neck 1a. Reference numeral 3 denotes a phosphor screen, which is usually a phosphor that emits red, green, and blue light is applied to the inner surface of the panel 1c in a mosaic pattern. FIG. 17 is an enlarged perspective view of the fluorescent screen portion of the color cathode ray tube, in which 4 is a shadow mask,
18, the through holes 6 for the electron beams 9 are formed in a predetermined array, as shown in FIG. 5
Is a frame, and the periphery of the shadow mask 4 is reinforced by fixing the peripheral edge of the shadow mask 4 to the side wall 5a facing the skirt of the panel 1c by welding or the like.

Reference numeral 7 denotes a spring, one end of which is a side wall 5
The shadow mask groove 20 is formed by fixing it to a.
A through hole (not shown) formed at the other end of the spring 7 is attached by being combined with a pin (not shown) implanted on the inner surface of each side of the skirt portion of the panel 1c. And the phosphor screen 3 are configured to face each other at a predetermined interval. Reference numeral 8 is a magnetic shielding member called an internal magnetic shield, which is formed into a truncated pyramid shape along the shape of the funnel 1b by a thin plate having high magnetic permeability, and a peripheral edge portion 8a at the front end thereof is on the electron gun 2 side of the frame 5. It is fixed by welding or the like to the facing side 5b facing toward. Reference numeral 9 denotes an electron beam, which is deflected and scanned within a range shown by a dashed line in FIG. 17 by a deflecting means (not shown).
The electron beam 9 that has passed through the electron beam passage hole 6 of the shadow mask 4 strikes the phosphor screen 3 to selectively cause the phosphor to emit light.

Next, the operation of the above configuration will be described.
The electron beam 9 emitted from the electron gun 2 is deflected and scanned by the deflecting means within the range shown by the dashed line in FIG. 17, and the electron beam 9 that has passed through the electron beam passage hole 6 of the shadow mask 4 is directed to the fluorescent surface 3. By the collision, the phosphor on the phosphor screen 3 selectively emits light. At this time, if the color cathode ray tube is placed in an environmental magnetic field such as geomagnetism, the flight trajectory of the electron beam 9 will be bent. The influence of such an environmental magnetic field is eliminated by the magnetic shielding member 8. That is, in the color cathode ray tube covered with the magnetic shield member 8, the environmental magnetic field is weakened by the shield, so that the flight trajectory of the electron beam 9 is less bent, and the incident position of the electron beam 9 on the fluorescent screen 3 is displaced. Is smaller, and the occurrence of color misregistration is reduced.

By the way, looking at the magnetic shielding effect of the magnetic shielding member 8, the color cathode ray tube is directed to the east (hereinafter referred to as "E").
Direction) or westward (hereinafter referred to as W direction), the magnetic shield member 8 and the frame 5 are installed.
Since the magnetic flux is concentrated on, the shielding effect in the space surrounded by these is sufficiently large. On the other hand, when the color cathode ray tube is installed in the north direction (hereinafter, referred to as N direction) or the south direction (hereinafter, referred to as S direction), the magnetic shield member 8 is largely opened in the direction of the phosphor screen 3. Because
The shielding effect is inferior to the E direction and the W direction. As described above, although there are differences in the magnetic shielding effects in the E-W and N-S directions, it is desirable that the shielding effects in these two directions are substantially the same. In the truncated pyramidal magnetic shield member 8, the magnetic shield effects in the E-W and N-S directions cannot be changed independently, and this point was empirically designed.

Particularly, in the color cathode ray tube of the type in which the phosphor screen 3 is composed of a set of elongated phosphor stripes in the vertical direction as shown in FIG. 18, the environment of the electron beam 9 during the operation in the EW direction. The bending due to the magnetic field is originally in the vertical direction, and therefore, it is less likely to cause a color shift. However, when the magnetic shield member 8 having a truncated pyramid shape as shown in FIG. In addition to the predetermined shielding effect for the cathode, there is a phenomenon that the direction of the environmental magnetic field changes in the cathode ray tube in a direction other than the EW direction, and it is often the case that the magnetic shielding member 8 is not used, which results in better results. There was a problem that the improvement of the effective shielding effect was not as intended.

In order to solve these problems, there have been inventions described in, for example, JP-A-6-36700 and JP-A-6-36701. JP-A-6-367
In the invention of Japanese Patent Publication No. 00, as shown in FIG. 19, one end is fixed to a frame, and the other end has a tip portion which extends toward the direction of the electron gun without touching another high magnetic permeability member and forms itself. A shield member 10 is provided. In addition, JP-A-6
According to the invention of Japanese Patent No. 36701, as shown in FIG. 20, as the magnetic shielding member 11, the ratio of length to thickness is 5: 1 or more,
A U-shaped magnetic body having a U-shaped elongated magnetic body having a length-width ratio of 5: 1 or more, one end of which is connected to the frame and the other end of which extends in the direction of the electron gun. Is equipped with.

However, the above-mentioned Japanese Laid-Open Patent Publication No.
In the conventional example as disclosed in Japanese Patent No. 36700, it is unavoidable that the magnetic field concentrates on the end of the magnetic shielding member and the orbit of the electron beam passing therethrough is bent to cause color misregistration. Further, in a conventional example such as Japanese Patent Application Laid-Open No. 6-36701 shown in FIG. 20, a magnetic field is concentrated at the connection point between the magnetic shield member 11 (U-shaped magnetic body) and the frame, and in this case also the electron beam is affected. Inevitably, the occurrence of color shift was inevitable. Further, in both of the conventional examples, since the length of the magnetic body in the Z direction is uniform as seen in the examples, only a very short shape is attached to prevent the magnetic body from touching the funnel. Therefore, the effect of magnetic shielding was very insufficient. Moreover, in these conventional examples, since each magnetic body is separately mounted, the mounting work becomes very complicated and the productivity is lowered.

The earth magnetism as an environmental magnetic field has a horizontal component and a vertical component, and the vertical component is caused by operating the color cathode ray tube in any direction of N-S-E-W (north, south, east and west). However, since the influence of the electron beam 9 on the orbit is constant and is almost constant over a fairly wide range on the earth, if the area of use of the color cathode ray tube on the earth is considered at the time of initial design, the color Inconvenient phenomena such as displacement can be greatly reduced. Therefore, in designing the magnetic shielding member 8, the shielding performance for the horizontal component of the earth's magnetism is important.

[0011]

Since the conventional color cathode ray tube is constructed as described above, in addition to the insufficient shielding effect by the magnetic shielding member, the color cathode ray tube has the EW direction. , Or the direction in which the magnetic shield member is magnetized differs depending on the magnetic field when installed in the N-S direction, there is a problem that the shield effect cannot be changed independently according to the direction in which each magnetic field is applied. It was
Also, the design of the magnetic shield often relies on experience,
It was troublesome.

The present invention has been made in view of the above situation, and effectively utilizes the shape effect of the magnetic material to efficiently reduce the mislanding amount only for an external magnetic field in one direction. It is an object of the present invention to provide a color cathode ray tube including a magnetic shielding member that can be manufactured and can be easily designed and produced.

[0013]

A color cathode ray tube according to a first aspect of the present invention is a panel coated with a fluorescent screen, a shadow mask provided inside the panel, a frame for supporting the shadow mask, and an electron gun. A color cathode ray tube comprising a magnetic shielding member installed so as to sandwich the upper and lower sides of an electron beam emitted from the above, and a shadow mask, a frame, a magnetic shielding member, a funnel covering the electron gun and a neck, wherein the magnetic shielding member is , Rectangular portions that are integrally formed substantially parallel to the inner wall of the funnel and that extend from the frame in the direction of the electron gun are arranged at predetermined intervals in the lateral direction of the frame, and the rectangular portions are The length decreases from the center of the side of the frame toward both ends.

A color cathode ray tube according to a second aspect of the present invention includes a panel having a phosphor screen coated thereon, a shadow mask provided inside the panel, and a frame for supporting the shadow mask.
A magnetic shielding member installed so as to sandwich the upper and lower sides of an electron beam emitted from an electron gun, the shadow mask,
A color cathode ray tube comprising a frame, a magnetic shield member, a funnel covering an electron gun and a neck, wherein the magnetic shield member has a magnetic body formed in a zigzag shape from one end to the other end of the side portion of the frame. , The one bent part of the zigzag shape is fixed to the frame, the other bent part extends toward the electron gun, and from the frame near the center of the side part of the frame to the both ends. The length of the magnetic body up to the other bent portion is short.

In the color cathode ray tube according to the third aspect of the present invention, the magnetic shielding member is formed in a zigzag shape by using a U-shaped magnetic body as one unit shape. In the color cathode ray tube according to the fourth aspect of the present invention, the magnetic shielding member is formed in a zigzag shape with a U-shaped magnetic body as one unit shape. The magnetic shielding member in the color cathode ray tube according to the fifth aspect of the invention is such that a rectangular magnetic body is arranged in a grid pattern from the frame in the direction of the electron gun along the inner side of the funnel and is formed integrally with the side portion of the frame. It has been formed in a regular manner.

The magnetic shield member in the color cathode ray tube according to the sixth aspect of the invention is such that the length of a straight line portion from the portion fixed to the frame to the bent portion is 1, and the width of the magnetic shield member is b. Then, the length 1 and the width b are at least 1 / b ≧ 5. The magnetic shielding member in the color cathode ray tube according to the seventh invention is such that, when the length of the linear portion of the magnetic shielding member is l and the thickness is t, the length l and the thickness t are at least l / t ≧ 5. A certain section is constituted by a rod-shaped magnetic body having a rectangular shape.

In the magnetic shielding member of the color cathode ray tube according to the eighth aspect of the present invention, when the length of the linear portion of the magnetic shielding member is l and the diameter is r, the length l and the diameter r are at least l / r. The cross section of ≧ 5 is composed of a rod-shaped magnetic body having a circular shape.

[0018]

In the color cathode ray tube according to the first aspect of the present invention, the magnetic shield member is integrally formed substantially parallel to the inner wall of the funnel and has a rectangular portion extending from the frame in the direction of the electron gun. The rectangular portions are arranged at a predetermined interval in the lateral direction of the frame, and the lengths of the rectangular portions decrease from near the center of the lateral sides of the frame toward both ends. Due to the effect, the magnetic substance is magnetized along the length direction, and the induced magnetic field is emitted to the region surrounded by the magnetic substance, so that the shielding effect is large. Also,
Due to the shape anisotropy of the magnetic substance, the magnetic substance is easily magnetized only in the specific direction, and the external magnetic field in the specific direction can be removed. Further, since the magnetic shield member is integrally connected and integrally formed, the magnetic field does not concentrate on the end portion.

The magnetic shielding member in the color cathode ray tube according to the second aspect of the present invention is formed by connecting the frame side and the electron gun side with a magnetic body having a zigzag bent portion and a rectangular portion as one unit. Therefore, due to the shape effect, the magnetic substance is magnetized along the length direction, and the induced magnetic field is effectively emitted to the region surrounded by the legs of the magnetic substance, so that the shielding effect is large. In addition, the shape anisotropy of the magnetic substance makes it easy to magnetize only in a specific direction, and the influence of the external magnetic field in the specific direction can be efficiently removed. Moreover, since the magnetic shield is integrally connected and integrated, the magnetic field is not concentrated at the end.

Since the magnetic shielding member in the color cathode ray tube according to the third invention is integrally formed in a zigzag shape with the U-shape as one unit shape, the magnetic field component in the Z direction in the external magnetic field is in the Y direction. Can be converted into a magnetic field component of Since the magnetic shielding member in the color cathode ray tube according to the fourth aspect is integrally formed in a zigzag shape with the U-shape as one unit shape, the magnetic field component in the Z direction in the external magnetic field is generated in the Y direction. Can be converted into components. Further, since the internal magnetic shield is formed by connecting a rectangular magnetic body to the frame side and the electron gun side, the magnetic shield member has a feature of improving rigidity.

The magnetic shield member in the color cathode ray tube according to the fifth aspect of the present invention is formed integrally by connecting rectangular magnetic bodies on the frame side and the electron gun side, so that the rigidity is improved. The magnetic shield member in the color cathode ray tube according to the sixth, seventh, or eighth invention has an optimum magnetic shield by satisfying a predetermined relationship between its length and width, length and thickness, or length and diameter. Exert an effect.

[0022]

【Example】

Example 1. An embodiment of the present invention will be described below. The same parts as those of the conventional technique are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 is a perspective view of a main part of a cathode ray tube according to an embodiment of the present invention. In the figure, 4 is a shadow mask of a 20-inch color cathode ray tube, 5 is a frame, and 12 is a magnetic shielding member.
Has a substantially rectangular shape as a whole. The tube axis, that is, the direction of the normal line standing in the center of the shadow mask 4 is Z
The direction of the long side of the rectangular shadow mask 4 in the directions orthogonal to each other and perpendicular to each other is the X direction, and X, Z
The short side direction is defined as the Y direction so as to be orthogonal to both directions and form a right-handed system.

The magnetic shield member 12 is made of a zigzag magnetic body, and the magnetic shield member 12 made of the zigzag magnetic body has a thickness of 0.01 cm and a width b.
Is 1 cm, the total length 1 is 180 cm, and the semicircular portion with a zigzag bend has a diameter D = 2 cm and is made of pure iron. The linear portion of the zigzag-shaped magnetic body of the magnetic shielding member 12, that is, the leg length l0 is shorter than the central portion toward both ends,
The magnetic shield member 12 is adapted to fit in the funnel 1b. The magnetic shield member 12 is the shadow mask 4 described above.
Are arranged on the two long side walls 5c of the frame 5.
In FIG. 1, the magnetic shield member 12 has an upper long side wall 5c.
Those disposed only on the lower long side wall 5c are omitted. A portion of the magnetic shield member 12 that is not fixed to the long side wall 5c of the frame 5 extends mainly parallel to the Z direction while having a slight Y direction component along the funnel 1b not shown in FIG. The linear portions of the zigzag-shaped magnetic body are arranged so as not to be magnetically connected to each other. Further, it goes without saying that the magnetic shield member may be formed in a zigzag shape at least at intervals that are not magnetically connected.

Next, the operation of the magnetic shield member 12 will be described. Now, consider a situation in which the color cathode ray tube is arranged and operated in the direction of the N pole or the S pole. That is, when a magnetic field is applied from the Z direction, the magnetic shield member 12 is formed of a sufficiently elongated rod-shaped magnetic body, so that it is magnetized along a zigzag shape as shown in FIG. The magnetic shield member 12 is a U-shaped magnetic body PO as shown in FIG.
It is considered that Q is connected as one unit shape. When this U-shaped magnetic body is magnetized in the longitudinal direction, as shown in FIG. 5A, an N pole is formed at the tips P and Q of the U-shaped magnetic body, and an S pole is formed at the center O point. The induced magnetic field Hm is emitted. In the region surrounded by the U-shaped magnetic body PQO, the induced magnetic field has the opposite direction to the externally applied magnetic field He, and thus has a shielding effect.

FIG. 3 is a vector (arrow) showing the magnetic field distribution by synthesizing the external magnetic field when the magnetic field is applied to the magnetic shield member 12 from the Z direction and the induced magnetic field Hm generated from the magnetic shield member 12 in vector. So, in the area surrounded by legs, Z
It can be seen that the magnetic field in the direction is sufficiently weakened. When a magnetic field is applied parallel to the leg direction of the magnetic shield member 12 in this way, an external magnetic field is applied parallel to the longitudinal direction of the zigzag magnetic body, so that the magnetizing force effectively acts and a large magnetization M is generated. The intensity of the induced magnetic field is increased and the shielding effect is good. Further, as can be seen from FIG. 4, the magnetic field distribution is such that the magnetic field is absorbed near one curved portion of the magnetic shielding member 12 and exits near the other curved portion, and the Z-direction magnetic field component is changed to the Y-direction component. The Z-direction magnetic field component that affects the orbit of the electron beam is sufficiently weakened by also having the function of converting.

On the other hand, when an external magnetic field is applied at right angles to the longitudinal direction of the U-shaped magnetic body as shown in FIG. 5B, only the external magnetic field applied to the curved portion of the U-shaped magnetic body acts as a magnetizing force. The magnetic field applied to the leg portion does not act as a magnetizing force to be orthogonal to the magnetizing direction, but it is magnetized in one direction in the longitudinal direction because it is formed of a sufficiently elongated magnetic body. But,
The magnitude of the magnetization is much smaller than that when an external magnetic field is applied in the longitudinal direction as shown in FIG.
Is also small and has little shielding effect.

When an external magnetic field is applied from the X direction at right angles to the leg direction of the zigzag-shaped magnetic shield member 12 having a U-shaped magnetic body as a unit shape, the tip R is formed along the zigzag shape as shown in FIG. It is magnetized from the point to the other end point S without generating a magnetic pole on the way. However, since only the external magnetic field applied to the curved portion of the zigzag acts as the magnetizing force, the magnitude of the magnetization is small and the induced magnetic field Hm is also small. FIG.
Reference numeral 8 is a vector display in which the external magnetic field and the induced magnetic field Hm generated from the magnetic shield member 12 are combined and the magnetic field distributions are combined in vector form, and the externally applied magnetic field from the X direction is hardly found by the magnetic shield member 12.

As described above, the zigzag-shaped magnetic shield member has shape anisotropy in which the shield effect varies depending on the direction of the applied magnetic field. Moreover, the shielding effect when applying an external magnetic field in the longitudinal direction of the zigzag magnetic body can be easily made by changing the length of the straight part, that is, the leg length, and the shielding effect when applying an external magnetic field at right angles to the longitudinal direction. There is almost no effect. Therefore, there is a feature that the control of the shielding effect can be performed independently of each other.

The above situation will be described in detail below. In FIG. 18, which is an enlarged perspective view of the fluorescent portion of the color cathode ray tube, the stripe-shaped phosphor screen 3 is composed of a blue phosphor row B, a green phosphor row G, and a red phosphor row R, and is formed on the shadow mask 4. The electron beam passage holes 6 that correspond to the phosphor rows B, G, and R, respectively, correspond to the set of phosphors B, G, and R, and the electron beam 9 emitted from the electron gun 2 passes through the passage holes 6 of the shadow mask 4 and corresponds. It collides with B, G or R and emits a desired color.

However, in the color cathode ray tube having such a stripe-shaped phosphor screen 3, even if each electron beam 9 moves in the Y direction due to the influence of an external magnetic field such as geomagnetism, the phosphors of the same color. Since it always collides with the rows, there is no reduction in color purity. However, when the electron beam 9 receives a Lorentz force that moves in the X direction on the phosphor screen 3 due to the influence of an external magnetic field such as the earth's magnetism, the electron beam 9 deviates from the corresponding phosphor line or collides with another phosphor line. In some cases, color misregistration occurs.
Here, the Lorentz force F applied to the electron when the electron moves at the velocity V in the magnetic field of the magnetic flux density B is represented by F = e (V × B) (1). The Lorentz force Fx in the direction perpendicular to the phosphor row, that is, in the X direction is expressed by Fx = Vy · Bz−Vz · By (2). Here, Vy and Vz are Y of each electron
Direction, velocity component in the Z direction, By and Bz are magnetic flux density values in the Y direction and the Z direction, respectively. When Fx is close to zero, the amount of movement of the electron beam 9 in the X direction, that is, the left and right directions becomes small. , No color shift occurs.

The broken line in FIG. 9 shows only the frame 5 and the shadow mask 4 of the 20-inch color cathode ray tube shown in FIG. 17, and is 1.0 [Oe] (Oersted) from the Z direction.
A value obtained by applying a magnetic field corresponding to the environmental magnetic field of X, Yx, Y, Z components Bx ', By', Bz 'of the magnetic flux density in the tube is shown. The measurement is performed by using Z as a position variable along the trajectory of the electron beam 9 that enters the screen corner portion starting from the deflection center. Here, the deflection center refers to FIG.
At the point corresponding to the divergence center where the electron beam 9 emitted from the electron gun 2 diverges toward each point on the phosphor screen 3 by the magnetic field of the deflection yoke (not shown),
This point is defined as Z = 0. Although the earth magnetism as an environmental magnetic field is usually about 0.4 [Oe], it is intentionally set to a large value in order to improve the measurement accuracy.

In FIG. 9, from the deflection center (Z = 0) to 2
Up to 00 mm, the Z component of the magnetic field applied from the Z direction is the main, but as the shadow mask 4 is approached, B
Although the z component decreases and the By and Bx components also occur, the magnetic field distribution changes, but as a whole, Bz >> By, and the Lorentz force in the X direction largely works, as can be seen from the above formula (2). From the trajectory calculation of the electron beam 9 flying in such a magnetic field distribution, the mislanding amount at the corner portion of the phosphor screen 3 is 140 μm, which is a value that causes a complete color shift. In order to reduce the Lorentz force of Fx, the magnetic field distribution may be set so that Bz≈By, as can be seen from the above formula (2). That is, while reducing the Bz component,
The By component may be increased.

The solid line in FIG. 9 indicates an external magnetic field corresponding to an environmental magnetic field of 1.0 [Oe] (Oersted) from the Z direction in the case of having the magnetic shield member 10 made of the zigzag bent magnetic body shown in FIG. X, Y, Z components B of the magnetic flux density in the tube from the deflection center to the phosphor screen 3 when
The measured values of x, By and Bz are shown, and when the magnetic shielding member 10 made of a zigzag-shaped magnetic body is attached,
Bz is greatly reduced in the range from Z = 90 mm to the mask surface. Further, By increases in the range of Z = 60 to 200 mm, and as is apparent from the equation (2), the magnetic field distribution is changed so as to reduce the mislanding amount in the X direction. When the trajectory of the electron beam 9 flying in this magnetic field distribution is calculated and the mislanding amount at the corner is calculated,
The thickness is 37 μm, and the amount of mislanding is significantly reduced to 1/4 as compared with the case where the magnetic shielding member 12 is not attached. The magnitude of the induced magnetic field can be controlled by the dimensional conditions of the magnetic shield member 12, and the magnetic field distribution can be controlled by the arrangement and the number of arrangements when the magnetic shield member 12 is attached to the frame 5, and the mislanding amount with respect to the magnetic field in the Z direction can be minimized. Optimal design is possible.

On the other hand, FIG. 10 shows a case where the magnetic shield member 12 is not attached (broken line) and is attached (solid line) in the case shown in FIG. 1 when an external magnetic field of 1.0 [Oe] is applied from the X direction. ) Shows the measurement result of the magnetic field distribution, and when the magnetic shield member 12 is attached, there is no influence on the magnetic field distribution except that By is slightly increased. The orbit of the electron beam 9 flying in this magnetic field distribution is calculated, and the mislanding amount at the corner is calculated to be 49 μm, which is slightly larger than that in the case where the magnetic shielding member 10 is not attached. . However, the amount of mislanding is almost equal to that when an external magnetic field is applied from the Z direction, which is extremely effective in practice. Further, the magnetic shielding member 10
It is possible to design so that the mislanding amount with respect to the magnetic fields in the Z direction and the X direction is equalized depending on the dimensional conditions, the arrangement and the number of arrangements at the time of attachment to the frame 5.

If the magnetic shielding member 8 is not attached to the color cathode ray tube shown in FIG. 17, the bending of the electron beam 9 due to the magnetic field in the X direction is mainly in the Y direction, as is clear from Fleming's law. As shown in FIG. 18, if the phosphor screen 3 has a phosphor stripe structure elongated in the Y direction, the problem of color misregistration does not occur. However, in this state, there is no protection against the magnetic field in the Z direction, and a remarkable color shift is likely to occur, and the magnetic shield member 8 is attached in order to prevent this. This magnetic shielding member 8 is X
Although there is a certain degree of magnetic shielding effect on the magnetic field in the direction, it also has the effect of changing the direction of the magnetic field in the tube, and as a result, the magnetic shielding member 8 is not attached to the magnetic field in the X direction. In many cases, it is difficult to simultaneously reduce the effects of the magnetic fields in the Z direction and the X direction on the color shift.

On the other hand, as shown in the above embodiment,
By forming the plate-like magnetic body that is long and slender into a zigzag shape, the environmental magnetic field in the X direction is not significantly affected, and the shielding effect of the environmental magnetic field in the Z direction can be effectively exhibited. Further, since the magnetic shield member 12 is integrally formed in a zigzag shape having a U-shaped magnetic body as a unit shape, the structure is simplified, the productivity is improved, and the cost can be reduced.

By the way, when a ferromagnetic material is magnetized by an external magnetic field, its magnetization state largely depends on the shape of the ferromagnetic material. For example, FIGS. 11A to 11D show the integral equation of the distribution of the magnetization M when an external magnetic field He is applied at an angle of θ = 60 ° from the longitudinal direction of a plate-shaped magnetic body having a length 1 and a width b. Is analyzed and the result is represented by a vector. In the case of a square of (l / b) = 1 as shown in FIG. 7A, the directions of the external magnetic field and the magnetization M match,
It can be seen that as the value of (l / b) increases as shown in (b), (c) and (d) of the same figure, the direction of magnetization shifts to the longitudinal direction.

12 (a), (b), (c), (d)
Is θ = from the longitudinal direction of the plate-shaped magnetic body of (l / b) = 10.
The distribution of the magnetization M when an external magnetic field He is applied at an angle of 0 °, 30 °, 60 °, 90 ° is analyzed by an integral equation, and the result is represented by a vector. As can be seen from the figure, when the shape of the magnetic body is elongated, the magnetization M is oriented in the longitudinal direction regardless of the direction of the applied external magnetic field He. This is called a shape effect when the magnetic body is magnetized. Here, the following equation is established between the apparent magnetic permeability μ ′ of the magnetic body having an arbitrary shape, the demagnetizing factor N, and the magnetic permeability μ of the magnetic material.

[0039]

[Equation 1]

Since there is a relationship of Nl << Nb between the demagnetizing field coefficient Nl in the length direction and the demagnetizing field coefficient Nb in the width direction of the elongated plate-shaped magnetic body, the apparent magnetic permeability and the width in the length direction are equal to each other. The relationship with the apparent magnetic permeability μ'b in the direction is
μ′l >> μ′b, and the length direction of the plate-shaped magnetic body is the easy magnetization direction. From this fact, when the direction of magnetization in the central portion of the magnetic body is φ when an external magnetic field is applied at an angle θ from the longitudinal direction of the plate-shaped magnetic body, it is expressed as follows. φ = tan−1 (tan θ / k) where k = Nb / Nl

FIG. 13 shows the angle φ from the longitudinal direction of the magnetization when a magnetic field is applied at an arbitrary angle θ from the longitudinal direction of the plate-shaped magnetic body. It can be seen that the larger the value of k, that is, the longer the length of the plate-shaped magnetic body, the more the direction of magnetization φ is zero, that is, the longitudinal direction, regardless of θ. If k> 50, the magnetization direction of the plate-shaped magnetic body is φ within 10 ° in the range of θ of 0 to 84 °.
It can be considered that the plate-shaped magnetic body is magnetized only in the lengthwise direction, and the magnetization has only the lengthwise component. The value of k is a function of the size of the plate-shaped magnetic body, the magnetic material, and the magnitude of the externally applied magnetic field. The magnetic material is pure iron and the magnitude of the external magnetic field is 10 [Oe].
The following is true, and if the relationship of (l / b)> 10 is satisfied, k> 50, and the average magnetization direction is the longitudinal direction regardless of the external magnetic field application direction, except for the magnetic field perpendicular to the longitudinal direction. .

Next, the range of selection of the design constant of the present invention will be described. In FIG. 1, the magnetic shield member 12 is arranged on the longitudinal direction 5C of the frame, and
A portion of the second member 5 which is in contact with the frame 5C is fixed to the frame 5C by welding, a clip, or the like, and the other end is made of an elongated magnetic body forming a substantially semicircle. The magnetic shield member 12 is magnetized in the longitudinal direction regardless of the direction of the externally applied magnetic field, and the induction magnetic field is folded and concentrated in a region surrounded by a magnetic material to enhance the shielding effect. This is to magnetize along the zigzag magnetic body due to the shape effect, and in order to make this effect sufficient, the length of the magnetic shielding member 12 is larger than the width as described with reference to FIGS. 11 and 12. Needs to be large enough. That is, in the embodiment shown in FIG. 1, the leg length must be sufficiently large with respect to the width.

Specifically, as shown in FIG. 11, the leg length l
It is necessary that the distance between o and the width b is at least (lo / b) ≧ 5, and preferably (lo / b) ≧ 10. Similarly, between the length lo and the thickness t (lo / t)
It is necessary to satisfy ≧ 5, preferably (lo / t) ≧ 10. If such a relationship is maintained, the magnetization direction of the magnetic substance becomes substantially equal to the longitudinal direction of the magnetic substance. The relationship between the width b and the thickness t related to the rectangular cross-sectional shape of the zigzag-shaped magnetic body forming the magnetic shielding member 10 may be b ≧ t or b ≦ t as long as the leg length is sufficiently long. The ratio of the thickness to the thickness can be arbitrarily selected. Further, not only the rod-shaped magnetic body having a rectangular cross section but also the bent rod-shaped magnetic body can be formed by the round bar-shaped magnetic body. Further, it goes without saying that the magnetic shield member may be formed in a zigzag shape at least at intervals that are not magnetically connected.

As shown in the present embodiment, when a magnetic field is applied parallel to the leg direction of the zigzag magnetic shield member 12 having a U-shaped magnetic material as a unit shape, the zigzag magnetic material is elongated in the longitudinal direction. Since the external magnetic field is applied in parallel, the magnetizing force effectively acts to generate a large magnetization M, and the magnitude of the induced magnetic field increases. Moreover, since the magnetic shield members are connected to each other as a whole, there is no concentration of the magnetic field at the ends, and the electron gun side of the magnetic shield members is shaped so as to follow the funnel and is long at the central part, so that it is resistant to external environmental magnetic fields. Good shielding effect. Further, in the vicinity of one curved portion of the magnetic shielding member 12,
The magnetic field distribution is such that the magnetic field is sucked in and goes out from the vicinity of other curved portions, and it also has the function of converting the Z-direction magnetic field component into the Y-direction component.

Further, when an external magnetic field is applied from the X direction at a right angle to the leg direction of the zigzag-shaped magnetic shield member 12 having a U-shaped magnetic body as a unit shape, the magnetic pole is formed along the zigzag shape in the longitudinal direction. Is magnetized without causing However, the magnitude of magnetization is small and the induced magnetic field Hm is also small, and X
The externally applied magnetic field from the direction is hardly disturbed by the magnetic shield member 12.

Therefore, when the magnetic shield member 12 made of a zigzag magnetic body is attached to the environmental magnetic field from the Z direction, Bz is greatly reduced, By is increased, and X is increased.
This has the effect of reducing the amount of mislanding in the direction. On the other hand, with respect to the environmental magnetic field from the X direction, the magnetic field distribution is not affected except that By is slightly increased, and the mislanding amount at the corner portion of the phosphor screen is larger than that when the magnetic shielding member 10 is not attached. The amount of mislanding is almost the same as when an external magnetic field is applied from the Z direction, but it is extremely effective in practice. Further, it is possible to design the mislanding amounts to be equal to the magnetic fields in the Z direction and the X direction depending on the dimensional conditions of the magnetic shield member 12 and the arrangement and the number of the magnetic shield members 12 to be attached to the frame 5.

Example 2. The second embodiment of the present invention will be described below. FIG. 14 is a perspective view of an essential part of a cathode ray tube according to the second embodiment of the present invention. In this embodiment, the zigzag-shaped inner magnetic shield is formed by connecting U-shaped magnetic bodies as one unit shape. In the figure, 4 is a shadow mask of a 20-inch color cathode ray tube, 5 is a frame, 13 is a magnetic shielding member, and the shadow mask 4 has a substantially rectangular shape as a whole.
The tube axis, that is, the direction of the normal line standing in the center of the shadow mask 4 is the Z axis, and the long side direction of the rectangular shadow mask 4 is a direction orthogonal to the Z axis and the directions orthogonal to each other, and X, Z The short side direction is defined as the Y direction so as to be orthogonal to both directions and form a right-handed system. Since the other components are the same as those shown in FIG. 16, the reference numerals shown in FIG. 16 are used in the following description.

The magnetic shield member 13 is made of a zigzag magnetic body. The magnetic shield member 10 made of the zigzag magnetic body has a thickness of 0.01 cm and a width b.
Is 1 cm, the total length 1 is 180 cm, and the U-shaped part with a bent zigzag is of equal width and made of pure iron. The linear portion of the zigzag-shaped magnetic body of the magnetic shield member 13, that is, the leg length l
The o becomes shorter than the central part as it goes to both ends, so that the magnetic shielding member 13 fits in the funnel 1b. The magnetic shield member 13 is arranged on the two long side walls 5c of the frame 5 of the shadow mask 4. In addition, in FIG. 14, the magnetic shield member 13 has an upper long side wall 5c.
Those arranged only on the lower long side wall 5c are omitted. The portion of the magnetic shielding member 13 that is not fixed to the long side wall 5c of the frame 5 has a slight -Y direction component along the funnel 1b (not shown in FIG. 14) and is mainly parallel to the -Z direction. Is extended,
The zigzag linear parts are arranged so as not to be magnetically connected to each other. Further, it goes without saying that the magnetic shield member may be formed in a zigzag shape at least at intervals that are not magnetically connected.

Next, the operation of the magnetic shield member 13 will be described. Now, consider a situation in which the color cathode ray tube is arranged and operated in the direction of the N pole or the S pole. That is, when a magnetic field is applied from the Z direction, the magnetic shield member 13 is formed of a sufficiently elongated rod-shaped magnetic body, so that it is magnetized along the zigzag shape as shown in FIG.
It is considered that the magnetic shielding member 13 is formed by connecting U-shaped magnetic bodies as one unit shape. When this U-shaped magnetic body is magnetized in the longitudinal direction, an N pole is generated at one end and an S pole is generated at the other end of the U-shaped magnetic body as shown in FIG. 5A.
The induced magnetic field Hm is emitted from the pole toward the S pole. In the region surrounded by the U-shaped magnetic body, the induced magnetic field is the externally applied magnetic field He.
Since it is in the opposite direction, it has a shielding effect. Therefore, in the same manner as in FIG. 3, the external magnetic field when the magnetic field is applied to the magnetic shield member 13 from the Z direction and the induced magnetic field Hm generated from the magnetic shield member 13 are vector-synthesized and the magnetic field distribution is shown by a vector (arrow). In the area surrounded by the legs, the magnetic field in the Z direction is sufficiently weakened.

When a magnetic field is applied in parallel to the leg direction of the magnetic shield member 13 as described above, the external magnetic field is applied in parallel to the longitudinal direction of the zigzag-shaped magnetic body, so that the magnetizing force works effectively and is large. The magnetization M is generated, the magnitude of the induced magnetic field is increased, and the shielding effect is good. Further, similar to that shown in FIG. 4, in the vicinity of one U-shaped portion of the magnetic shield member 13, a magnetic field distribution is such that the magnetic field is absorbed and goes out from the vicinity of the other U-shaped portion, and the Z-direction magnetic field component is changed in the Y direction. It also has the effect of converting to components.

On the other hand, when an external magnetic field is applied at right angles to the longitudinal direction of the U-shaped magnetic body, only the external magnetic field applied to the U-shaped end portion of the U-shaped magnetic body acts as a magnetizing force, and is applied to the leg portion. The magnetic field does not act as a magnetizing force to be orthogonal to the magnetization direction, but since this magnetic body is formed of a sufficiently elongated magnetic body, it is magnetized in the longitudinal direction and in one direction. However, compared with the case where an external magnetic field is applied in the longitudinal direction, the magnitude of the magnetization is much smaller, the induced magnetic field Hm is also smaller, and the shielding effect is less.

When an external magnetic field is applied from the X direction at a right angle to the leg direction of the zigzag-shaped magnetic shielding member 13 having a U-shaped magnetic body as a unit shape, the zigzag shape is formed in the longitudinal direction as shown in FIG. It is magnetized along the shape from the tip of the U-shape to the other end of the U-shape without generating a magnetic pole on the way. However, the magnitude of magnetization is small and the induced magnetic field Hm is also small. The magnetic field distribution obtained by combining the external magnetic field and the induced magnetic field Hm generated from the magnetic shielding member 13 is similar to that shown in FIGS. 7 and 8, and in the case of this embodiment, the externally applied magnetic field from the X direction is also generated by the magnetic shielding member 13. Hardly ever found.

As described above, the zigzag-shaped magnetic shield member has shape anisotropy in which the shield effect varies depending on the direction of the applied magnetic field. Moreover, when an external magnetic field is applied in the longitudinal direction of the zigzag folded magnetic body, the shielding effect can be easily changed by changing the length of the straight portion, that is, the leg length. Further, there is almost no shielding effect when an external magnetic field is applied at right angles to the longitudinal direction, but it can be somewhat changed depending on the size of the U-shaped portion. Therefore, the shielding effect can be controlled independently of each other depending on the direction in which the external magnetic field is applied. Further, a magnetic shield member 13a having a shape as shown in FIG. 15 is also conceivable.

As shown in the above-mentioned embodiment, by forming a plate-shaped magnetic body having a sufficiently long slender shape into a zigzag shape, the shape anisotropy of the magnetic body has little influence on the environmental magnetic field in the X direction. Without providing, the shielding effect can be effectively exerted on the environmental magnetic field in the Z direction. Furthermore, since the magnetic shielding member 13 is integrally formed in a zigzag shape having a U-shaped magnetic body as a unit shape, the structure of the magnetic shielding member is simplified, the productivity is improved, and the cost can be reduced.

Example 3. The third embodiment of the present invention will be described below. FIG. 16 is a view of the essential parts of a cathode ray tube according to the third embodiment of the present invention. In this embodiment, the zigzag-shaped internal magnetic shield is formed by connecting a rectangular magnetic body to the frame side and the electron gun side. In the figure, 4 is a shadow mask of a 20-inch color cathode-ray tube, 5 is a frame, 14 is a magnetic shield member, 14a is a rectangular magnetic body forming the magnetic shield member 14, and 14b is a rectangular magnetic body forming the magnetic shield member 14. The shadow mask 4 is a magnetic body and has a substantially rectangular shape as a whole. Tube axis,
That is, the Z axis is the direction of the normal line standing in the center of the shadow mask 4, and the long side direction of the rectangular shadow mask 4 is the X direction, which is orthogonal to the Z axis and perpendicular to each other.
The short side direction is defined as the Y direction so as to form a right-handed system orthogonal to both the X and Z directions. Since the other components are the same as those shown in FIG. 17, the reference numerals shown in FIG. 17 will be used in the following description.

The magnetic shield member 14 is a rectangular magnetic body 1.
It is composed of 4a and 14b, and the whole shape is trapezoidal. Magnetic shielding member 1 made of this rectangular magnetic body
4 is a rectangular magnetic body having a thickness of 0.01 cm and a width b of 1 cm, which is formed by connecting the frame 5 side along the frame long side wall side and the electron gun side along the inner side of the funnel. The magnetic material used is of equal width and made of pure iron. Leg length lo of the rectangular magnetic body 14a of the magnetic shield member 14
Is shorter than the central portion as it goes to both ends, so that the magnetic shield member 14 can fit in the funnel 1b. The magnetic shielding member 14 is arranged on the two long side walls 5c of the frame 5 of the shadow mask 4. Note that in FIG. 15, the magnetic shield member 14 has an upper long side wall 5c.
Those disposed only on the lower long side wall 5c are omitted. The portion of the magnetic shield member 14 that is not fixed to the long side wall 5c of the frame 5 extends mainly in the -Z direction along the funnel 1b (not shown in FIG. 16) with a slight -Y direction component. There is.

Next, the operation of the magnetic shield member 14 will be described. Now, consider a situation in which the color cathode ray tube is arranged and operated in the direction of the N pole or the S pole. That is, when a magnetic field is applied from the Z direction, the magnetic shield member 14 is formed of a sufficiently elongated rod-shaped magnetic body, so that it is magnetized along the length direction of the magnetic shield member as shown in FIG. . It is considered that the magnetic shield member 14 is formed by connecting rectangular magnetic bodies 14a as one unit. When this rectangular magnetic body is magnetized in the longitudinal direction, an N pole is formed at one end and an S pole is formed at the other end of the rectangular magnetic body as shown in FIG.
The induced magnetic field Hm toward the pole is emitted. Rectangular magnetic body 14
In the region surrounded by a and 14b, the induced magnetic field has a shielding effect because it is in the opposite direction to the externally applied magnetic field He. Therefore, in FIG. 3, when the magnetic field is applied to the magnetic shield member 12 from the Z direction, the external magnetic field and the induced magnetic field H generated from the magnetic shield member 12 are generated.
Vector (arrow) of the magnetic field distribution that combines m in vector
Similarly to the above, the magnetic field in the Z direction is sufficiently weakened in the region surrounded by the legs. When a magnetic field is applied parallel to the leg direction of the magnetic shield member 14 in this way, the rectangular magnetic body 14a
Since an external magnetic field is applied in parallel in the longitudinal direction of the magnetic field, the magnetic force effectively acts to generate a large magnetization M, the magnitude of the induced magnetic field is increased, and the shielding effect is good. Further, similarly to the case shown in FIG. 4, in the vicinity of one end of the magnetic shield member 14, a magnetic field is absorbed such that the magnetic field is absorbed and goes out from the vicinity of the other end, and the Z direction magnetic field component is changed to the Y direction component. It also has the function of converting.

On the other hand, when an external magnetic field is applied at right angles to the longitudinal direction of the magnetic shielding member, the magnetic field applied to the rectangular magnetic body 14a (leg portion) does not become a magnetizing force to be orthogonal to the magnetizing direction and is rectangular. Although the magnetic body 14a is not magnetized, the rectangular magnetic body 14b is magnetized by the magnetic force of the external magnetic field applied to the rectangular magnetic body 14b, and is magnetized in the longitudinal direction and in one direction. However, the rectangular magnetic body 14b has only two magnetic bodies on the frame side and the electron gun side, the induced magnetic field Hm is small, and the shielding effect is small.

As described above, the rectangular magnetic shield member has shape anisotropy in which the shield effect varies depending on the direction of the applied magnetic field.
Moreover, when an external magnetic field is applied in the longitudinal direction of the rectangular magnetic body, the shielding effect can be easily changed by changing the length of the straight portion, that is, the leg length, and the external magnetic field can be made perpendicular to the longitudinal direction. There is almost no shielding effect when applied, and therefore the shielding effect can be controlled independently of each other according to the direction of application of the external magnetic field. Further, it goes without saying that the magnetic shield members may be formed in a lattice shape with the rectangular magnetic bodies 14a at least at intervals that do not magnetically connect.

As shown in the above embodiment, by forming the magnetic shield member with a sufficiently elongated plate-shaped magnetic body, the magnetic shield member 14 is longitudinally moved by the shape effect of the magnetic body regardless of the direction of the externally applied magnetic field. , The induced magnetic field concentrates in the region surrounded by the rectangular magnetic material, and due to the shape anisotropy, it does not affect the environmental magnetic field in the X direction so much.
It is possible to effectively exert the effect of shielding the environmental magnetic field in the Z direction.

Further, the magnetic shielding member 14 is formed by connecting the rectangular magnetic body as one unit so that the frame side is along the frame long side wall side and the electron gun side is along the inner side of the funnel. Very strong and easy to manufacture. Although the magnetic shield member of this embodiment has a trapezoidal shape as shown in FIG. 16, it does not necessarily have to be a trapezoidal shape, as long as the length of the magnetic material at both ends is shorter than that of the central portion, and the overall shape. Can be appropriately selected.

In the first to third embodiments, the case of the 20-inch cathode ray tube has been described, but the size of the color cathode ray tube is not limited to 20 inches, and the magnetic field according to the present invention may be changed according to the size of the cathode ray tube. If you use a shielding member,
The same effects as those described in Examples 1 to 3 can be obtained.

[0063]

According to the color cathode ray tube according to the first aspect of the invention, a large magnetization is generated in the magnetic shield member with respect to the magnetic field from the Z direction, the magnitude of the induced magnetic field is increased, and the external magnetic field is shielded. You can For the magnetic field from the X direction,
It is magnetized along the shape of the magnetic shield member without generating magnetic poles on the way, but the magnitude of the magnetization is small and the induced magnetic field is also small. Therefore, the magnetic shielding member hardly disturbs the magnetic field applied from the X direction. In addition, since the magnetic shield member is integrally connected and integrated, the magnetic field does not concentrate at the end portion, so that the influence on the trajectory of the electron beam can be reduced. Further, the magnetic shielding member is formed along the funnel, and the linear portion in the central portion is longer than both ends, so that the shielding effect is high. Therefore, it has an effect of reducing the mislanding amount in the X direction with respect to the environmental magnetic field from the Z direction. On the other hand, the environmental magnetic field from the X direction does not affect the magnetic field distribution, but the amount of mislanding at the corner is almost the same as when an external magnetic field is applied from the Z direction, so in practice It is extremely effective.

Further, according to the color cathode ray tube of the second invention, since the magnetic shielding member is formed in a zigzag shape, a large magnetizing force is generated with respect to the external magnetic field, and the magnitude of the induced magnetic field is increased. Since the entire magnetic shield member is connected, the magnetic field does not concentrate at the end. Further, since the magnetic shielding member is formed along the inner side of the funnel and the central portion is longer than both ends, the shielding effect against the external magnetic field is high. Further, the magnetic field is absorbed such that the magnetic field is sucked from the vicinity of the curved portion on one side of the zigzag-shaped magnetic shielding member and emerges from the vicinity of the curved portion on the opposite side, and the magnetic field component in the Z direction is converted into a component in the Y direction. You can Therefore, the Z-direction component that influences the trajectory of the electron beam can be sufficiently weakened and the mislanding amount can be reduced, so that there is an effect of eliminating the color misregistration. Further, by forming the magnetic shield member in a zigzag shape, the shield effect for the external magnetic field in the longitudinal direction and the external magnetic field in the direction perpendicular to the longitudinal direction of the zigzag magnetic body can be controlled independently due to the shape anisotropy of the magnetic body. Became possible.

According to the color cathode ray tube of the third aspect of the present invention, the zigzag-shaped magnetic shielding member having a U-shaped unit does not disturb the external magnetic field applied in the X direction. Therefore, the amount of mislanding in the X direction is reduced with respect to the environmental magnetic field from the Z direction, and X
With respect to the environmental magnetic field from the direction, the amount of mislanding is almost equal to that when an external magnetic field is applied from the Z direction, which is extremely effective in practice. Further, the shielding effect can be adjusted by changing the size of the magnetic shielding member, the position and number of the magnetic shielding member to be attached, and the like. Furthermore, since it is formed in a zigzag shape using the U-shape as a unit shape, the structure is simplified, the productivity is improved, and the cost can be reduced.

Further, in the color cathode ray tube according to the fourth aspect of the present invention, the zigzag-shaped magnetic shield member having a U-shaped unit does not disturb the external magnetic field applied in the X direction. Therefore, the amount of mislanding in the X direction is reduced with respect to the environmental magnetic field from the Z direction, and X
With respect to the environmental magnetic field from the direction, the amount of mislanding is almost equal to that when an external magnetic field is applied from the Z direction, which is extremely effective in practice. Further, the shielding effect can be adjusted by changing the size of the magnetic shielding member, the position and number of the magnetic shielding member to be attached, and the like. Further, since the magnetic shield member is integrally formed with the U-shape as a unit shape, the structure is simplified, the productivity is improved, and the cost can be reduced.

According to the color cathode ray tube of the fifth aspect of the present invention, the magnetic shield member 10 is formed of a rectangular magnetic body as one unit so that the frame side is along the frame long side wall and the electron gun side is the funnel. Since it is formed in a lattice shape by connecting along the inner side, it has a structurally high strength and is easy to manufacture.

Furthermore, according to the color cathode ray tube according to the sixth, seventh or eighth aspect of the invention, the ratio of the dimensions of the magnetic shielding member is optimized, so that the shielding effect against the external magnetic field is good,
The amount of mislanding with respect to the Z-direction and X-direction magnetic fields can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a color cathode ray tube according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a magnetized state of a magnetic shield member when an external magnetic field is applied from the Z direction.

FIG. 3 is a diagram showing a magnetic field distribution when an external magnetic field is applied to the magnetic shield member from the Z direction.

FIG. 4 is a diagram showing a magnetic field distribution when an external magnetic field is applied to the magnetic shield member from the Z direction.

FIG. 5 is a diagram showing a magnetic field distribution when an external magnetic field is printed on the magnetic shield member from the Z direction.

FIG. 6 is a diagram showing a magnetized state of a magnetic shield member when an external magnetic field is applied from the X direction.

FIG. 7 is a diagram showing a magnetic field distribution when an external magnetic field is printed on the magnetic shield member in the X direction.

FIG. 8 is a diagram showing a magnetic field distribution when an external magnetic field is printed on the magnetic shield member in the X direction.

FIG. 9 is a diagram showing magnetic flux densities with and without a magnetic shield member in a state where an external magnetic field is applied from the Z direction.

FIG. 10 is a diagram showing magnetic flux densities with and without a magnetic shield member in a state where an external magnetic field is applied from the X direction.

FIG. 11 is a diagram showing magnetization states of various plate-shaped magnetic bodies in a uniform magnetic field.

FIG. 12 is a diagram showing a magnetization state of a plate-shaped magnetic body with respect to a direction in which a uniform magnetic field is applied.

FIG. 13 shows the magnetization direction when the magnetic field is applied at an arbitrary angle θ from the longitudinal direction of the plate-shaped magnetic body, the angle φ from the longitudinal direction.
It is the figure shown by.

FIG. 14 is a perspective view of a main part of a color cathode ray tube according to a second embodiment of the present invention.

FIG. 15 is a diagram of a main part of a color cathode ray tube according to a third embodiment of the present invention.

FIG. 16 is a diagram of a main part of a color cathode ray tube according to a third embodiment of the present invention.

FIG. 17 is a cross-sectional view showing a conventional cathode ray tube device.

FIG. 18 is an enlarged perspective view of a fluorescent screen portion of a color cathode ray tube.

FIG. 19 is a perspective view of a main part of a conventional color cathode ray tube.

FIG. 20 is a perspective view of a main part of a conventional color cathode ray tube.

[Explanation of symbols]

1. Tube 1a. Neck portion 1b. Funnel part 1
c. Panel section 2. Electron gun 3. Fluorescent screen 4. Shadow mask 5. Frame 5a. Side wall 5b. Opposing side 5c. Long side wall 6. Through hole 7. Spring 8. Magnetic shielding member 8a. Edge portion 9. Electron beam 1
0. Magnetic shielding member 10a. Leg portion 10b. Rectangular magnetic body 12. Magnetic shielding member 13. Magnetic shielding member 14. Magnetic shielding member 20. Shadow mask structure

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideo Ikeda 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Sanryo Electric Co., Ltd. Materials and Devices Laboratory (72) Yoshihiro Tani 8th Street, Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture No. 1-1 Sanryo Electric Co., Ltd. Material and Device Research Center

Claims (8)

[Claims] 1. A panel coated with a phosphor screen, a shadow mask provided on the inside of the panel, a frame supporting the shadow mask, and a top and bottom of an electron beam emitted from an electron gun. In a color cathode ray tube comprising a magnetic shield member, a shadow mask, a frame, a magnetic shield member, a funnel covering an electron gun and a neck, the magnetic shield member is integrally formed substantially parallel to an inner wall of the funnel, and Rectangular portions extending from the frame in the direction of the electron gun are arranged at predetermined intervals in the lateral direction of the frame, and the rectangular portions become shorter from the center of the lateral sides of the frame toward both ends. A color cathode ray tube characterized in that 2. A panel having a fluorescent screen adhered thereto, a shadow mask provided inside the panel, a frame for supporting the shadow mask, and an electron beam emitted from an electron gun installed so as to sandwich the upper and lower sides of the frame. In the color cathode ray tube including the internal magnetic shield means, the shadow mask, the frame, the magnetic shield member, the funnel covering the electron gun, and the neck, the magnetic shield member has a magnetic body from one end to the other end of the side portion of the frame. The bent part of the zigzag shape is fixed to the frame, the other bent part extends toward the electron gun, and is near the center of the side part of the frame. A color cathode ray tube characterized in that the length of the magnetic body from the frame to the other bent portion becomes shorter as going from the frame to both ends. 3. The color cathode ray tube according to claim 2, wherein the magnetic shielding member forms a zigzag shape with a U-shaped magnetic body as one unit shape. 4. The color cathode ray tube according to claim 2, wherein the magnetic shielding member forms a zigzag shape with a U-shaped magnetic body as one unit shape. 5. The magnetic shield member is formed integrally with a rectangular magnetic body along the inner side of the funnel in a grid pattern from the frame toward the electron gun in the side portion of the frame. The color cathode ray tube according to claim 1, wherein 6. The length l when the length of a straight line portion from the portion where the magnetic shield member is fixed to the frame to the bent portion is l and the width of the magnetic shield member is b The color cathode ray tube according to claim 1, wherein the width b is at least 1 / b ≧ 5. 7. The magnetic shield member has a rectangular cross section in which the length l and the thickness t are at least 1 / t ≧ 5, where l is the length of a straight line portion of the magnetic shield member and t is the thickness thereof. It is a rod-shaped magnetic body, It is characterized by the above-mentioned.
The color cathode ray tube according to any one of 1. 8. The magnetic shield member has a rod-like shape with a circular cross section in which the length l and the diameter r are at least 1 / r ≧ 5, where r is the length of the linear portion of the magnetic shield member. The color cathode ray tube according to claim 1, wherein the color cathode ray tube is a magnetic material.