JP2001268586A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode ray tube display device having a large shield effect of an external magnetic field of a color selection electrode and having a uniform degaussing coils. SOLUTION: The display device is provided with a frame 11 to support the color selection electrode having a pore for passage for an electronic beam, an internal magnetic shield 12 to shield the electronic beam from magnetism, an electron beam emitting means 13, a funnel 14 to be joined to a display panel 10 so as to cover the color selection electrode, a frame and the internal magnetic shield and firs and second degaussing coils arranged approximately along the funnel, the first degaussing coil 16a has a first side to be arranged higher than an upper side of the color selection electrode and approximately in parallel with the upper side of the color selection electrode, the second degaussing coil 16b has a second side to be arranged lower than a lower side of the color selection electrode and approximately in parallel with the lower side of the color selection electrode and at least one part of the first and second degaussing coils is bent in the direction to come closer to the other degaussing coil each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cathode ray tube (hereinafter, referred to as a cathode ray tube).
(CRT) or a display device such as a television having a CRT.

[0002]

2. Description of the Related Art In a CRT, an electron beam emitted from an electron beam emitting means, which is an electron gun, passes through a hole for passing an electron beam of a color selection electrode and hits a phosphor at a landing point of the electron beam. Emit any one of red, green and blue. Hereinafter, a conventional CRT display device will be described with reference to the drawings. FIG.
Is a perspective view for explaining the configuration of a CRT as a conventional display device, FIG. 13 is an explanatory diagram showing a degaussing coil structure of the conventional CRT, and FIG. 14 is an explanatory diagram showing a shadow mask which is a color selection electrode structure of the CRT. FIG. 15 is an explanatory view showing a tension mask which is a color selection electrode structure of a CRT.

[Explanation of FIG. 14] A shadow mask 11a shown in FIG. 14 is a representative example of a color selection electrode structure including a color selection electrode 20 and a frame 21. The shadow mask 11a is obtained by fixing a color selection electrode 20 having a large number of pores formed into a predetermined shape by press working and welding it to a frame 21. When the electron beam collides with the color selection electrode 20, the color selection electrode 2
0 may be deformed due to thermal expansion due to a temperature rise, which may cause a positional relationship with the phosphor to shift and cause color shift. [Explanation of FIG. 15] As a color selection electrode assembly for solving this problem, as shown in FIG. 15, a color selection electrode 20 having a large number of pores is tensioned while tension is applied thereto. A tension mask 11b for fixing the frame 20 to the frame 21 has been proposed. According to this method, the frame of the tension mask 11b to which tension is applied absorbs the elongation due to thermal expansion caused by the collision of the electron beam, and prevents deformation.

[Explanation of FIG. 12] However, when an external magnetic field such as terrestrial magnetism is applied while the electron beam reaches the fluorescent screen of the display panel 10 from the electron beam emitting means 13, the electron beam receives Lorentz force, The trajectory changes, the landing lands at a point shifted from the landing point when there is no external magnetic field, and a part or all of the beam spot hits a phosphor different from that when there is no external magnetic field, causing color shift. The internal magnetic shield 12
And an external magnetic field shield structure is constituted by this and the color selection electrode assembly 11, which shields the external magnetic field, suppresses the change in the trajectory of the electron beam due to the external magnetic field, and suppresses the color shift. [Explanation of FIG. 13] In order to further improve the magnetic shielding effect, in the conventional display device, a first degaussing coil 16a and a second degaussing coil 16b, each of which has a substantially planar shape, are shown in FIG. Are arranged as shown,
A degauss operation is performed by passing a degaussing current through the two degaussing coils. The degauss operation is an operation of applying a decaying alternating magnetic field starting from an amplitude to the magnetic shield member that is magnetically saturated or higher. First degaussing coil 16a and second degaussing coil 16
By passing an attenuated alternating current through b, the attenuated alternating magnetic field is realized. By this degauss operation, the effective magnetic permeability of the magnetic shield member can be increased, the shielding effect of the external magnetic field is increased, the change in the trajectory of the electron beam due to the external magnetic field is suppressed, and the color shift is suppressed.

[0005]

In the tension mask as shown in FIG. 15, the frame 21 has the color selection electrode 2
In order to apply a tension to zero, an angle 21 a which is a first frame supporting the color selection electrode 20 and an angle 21
and an arm 21b that is a second frame that is joined to a and applies a tension to an end of the color selection electrode 20. However, due to this structure, a horizontal magnetic field, which is an external magnetic field in the side direction of the arm 21b and in the tube axis direction of the CRT, is not sufficiently shielded. Furthermore, in the degauss operation using the degaussing coil as described above, it is insufficient to increase the effective magnetic permeability of the magnetic shield member, and the horizontal magnetic field is not sufficiently shielded. There is a problem that the color shift cannot be sufficiently suppressed and the color shift cannot be sufficiently suppressed. SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to provide a display device that can sufficiently suppress color misregistration as compared with the conventional method, and that can achieve extremely high image quality.

[0006]

According to a first aspect of the present invention, there is provided a display panel having a phosphor screen, an electron beam emitting means for emitting an electron beam toward the display panel, A color selection electrode having pores for passage, a frame supporting the color selection electrode, an internal magnetic shield for shielding the electron beam from magnetism, the electron beam emitting means, the color selection electrode, the frame and the inside A display device comprising: a funnel joined to the display panel so as to cover a magnetic shield; and first and second degaussing coils disposed substantially along the funnel. The coil is above the upper side of the color selection electrode and substantially parallel to the upper side of the color selection electrode,
Having a first side disposed, wherein the second degaussing coil is
A second side disposed below the lower side of the color selection electrode and substantially parallel to the lower side of the color selection electrode; and
A display device, wherein at least a part of the first and second degaussing coils are each bent in a direction approaching another degaussing coil.

[0007] Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, and the effective magnetic permeability of the color selection electrode can be increased.
This has the effect that the effect of shielding the external magnetic field is increased, the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, and the color shift can be sufficiently suppressed.

In the present specification and claims, the expression above or below generally means a direction in a normal use state of the display device, but a state in which the display device is turned sideways. The present invention also falls under the technical scope of the present invention. Even in such a case, the demagnetizing magnetic field generated from the demagnetizing coil efficiently flows to the color selection electrode, which has a unique effect of the present invention. In the present specification and the description of the appended claims, the terms left, right, front and back are expressions from the viewpoint of viewing the display of the display device. Therefore, “before” means a direction in which the display device approaches a person who is watching the display on the display device. In the present specification and the description of the claims, the terms upper side, lower side, and vertical side of the color selection electrode refer to the color selection electrode 20 (FIG. 14 or FIG. 15) having a substantially rectangular shape and a small thickness. The upper side, the lower side, and the vertical side of a substantially rectangular shape are meant.

According to a second aspect of the present invention, at least two sides of each of the first and second degaussing coils are substantially along a side surface of the funnel and the first and second degaussing coils are provided with a color selection electrode. 2. The display device according to claim 1, wherein the display device is arranged in parallel with the left and right vertical sides.
Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. In this case, the change in the trajectory of the electron beam due to the external magnetic field can be sufficiently suppressed, and the color shift can be sufficiently suppressed.

The invention according to claim 3 of the present invention is characterized in that the first and second degaussing coils are further disposed vertically symmetrically with respect to each other. A display device. Thereby, the same degaussing coil can be used as the first and second degaussing coils. Thereby, the type of the degaussing coil to be used can be made one, and the number of the single degaussing coils used is doubled. This has the effect that the cost of the degaussing coil can be reduced.

According to a fourth aspect of the present invention, the first degaussing coil has a third side disposed substantially along a side surface of the funnel, and the second degaussing coil has a third side. And a fourth side disposed substantially along a side surface of the funnel, wherein the third side and the fourth side are disposed substantially in parallel with each other. Item 14. The display device according to Item 3. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode,
The effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field increases, the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction can be sufficiently suppressed, and the color shift can be sufficiently suppressed. It has the action of:

The invention according to claim 5 of the present invention is characterized in that the third side and the fourth side are further disposed near a side surface of the color selection electrode. A display device according to claim 4. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. In this case, the change in the trajectory of the electron beam due to the external magnetic field can be sufficiently suppressed, and the color shift can be sufficiently suppressed.

The invention according to claim 6 of the present invention is characterized in that the third side and the fourth side are further arranged close to each other. It is a display device of an embodiment. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. The change in the trajectory of the electron beam due to the external magnetic field is sufficiently suppressed,
This has the effect that color shift can be sufficiently suppressed.

The invention according to claim 7 of the present invention is characterized in that the first degaussing coil and the second degaussing coil are formed by one coil. A display device according to claim 6. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. In this case, the change in the trajectory of the electron beam due to the external magnetic field can be sufficiently suppressed, the color shift can be sufficiently suppressed, and the cost can be reduced by reducing the number of parts.

According to an eighth aspect of the present invention, a plane defined by the first side and the second side is larger than a plane defined by the first side and the second side.
The display device according to claim 1, wherein at least a part of each of the first degaussing coil and the second degaussing coil is disposed forward, respectively. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. In this case, the change in the trajectory of the electron beam due to the external magnetic field can be sufficiently suppressed, and the color shift can be sufficiently suppressed.

According to a ninth aspect of the present invention, at least one side of each of the first degaussing coil and the second degaussing coil is disposed on an explosion-proof band. A display device according to claim 1. Thereby, in the degauss operation, the degaussing magnetic field generated from the degaussing coil efficiently flows to the color selection electrode, the effective magnetic permeability of the color selection electrode can be increased, the shielding effect of the external magnetic field is increased, and the horizontal direction is improved. In this case, the change in the trajectory of the electron beam due to the external magnetic field can be sufficiently suppressed, and the color shift can be sufficiently suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to fifth embodiments of the present invention will be described.

<< Embodiment 1 >> A first embodiment of the present invention will be described with reference to FIGS. As a display device, CR
T is a color television. [Explanation of FIG. 1] FIG. 1 is a perspective view for explaining a configuration of a CRT as a display device according to a first embodiment of the present invention. Only those structures that are deeply related to the change in are shown. FIG. 2 is an explanatory view showing the degaussing coil structure of the first embodiment. The embodiment and the conventional example have the same configuration except for the degaussing coil.

In FIG. 1, the color television of this embodiment has a display panel 10 having a fluorescent screen and electron beam emitting means 13 for emitting an electron beam toward the display panel 10.
(For example, an electron gun), a color selection electrode assembly 11 and an internal magnetic shield 12 are provided. Further, the color television of this embodiment further includes a funnel 14 joined to the display panel 10 so as to cover the electron beam emitting means 13, the color selection electrode assembly 11 and the internal magnetic shield 12, and an electron beam along the funnel 14. A first degaussing coil 16a and a second degaussing coil 16b are provided above and below the emission unit 13. Color selection electrode assembly 1
1 has the structure of FIG. 14 or FIG. The present invention is particularly effective in a display device having the color selection electrode structure 11 having the structure shown in FIG.

The electron beam emitted from the electron beam emitting means 13 passes through the aperture for passing the electron beam of the color selection electrode 20 (the front surface of the color selection electrode assembly 11) and is displayed at the landing point of the electron beam. The phosphor of the panel 10 emits one of red, green and blue. When the degauss operation is performed, the degaussing magnetic field generated by the first degaussing coil 16a and the second degaussing coil 16b efficiently flows through the magnetic shield formed by the color selection electrode assembly 11 and the internal magnetic shield 12.

In each of the conventional example and the first embodiment, the external magnetic field shield structure includes a color selection electrode structure 11 (tension mask 11b) shown in FIG. 15 and an internal magnetic shield 12 made of, for example, a 0.15 mm thick SPCC material. Consists of Color selection electrode assembly 11 (tension mask 11b)
Is an angle 21a that is a first frame made of a 36% Ni-Fe material having a thickness of 1.4 mm, for example, and an arm 21b is a second frame made of a 42% Ni-Fe material having a thickness of 1.4 mm, for example. And, for example, 36 with a thickness of 0.1 mm
% Ni—Fe material and a color selection electrode 20.

As shown in FIG. 13, the conventional degaussing coil has a substantially planar shape and a substantially quadrangular first degaussing coil 16a is provided with an explosion proof along the funnel 14 from below the electron beam emitting means 13. It passes through the upper corner portion of the band 15, passes through the upper portion of the explosion-proof band 15, passes through the other upper corner portion of the explosion-proof band 15, and is connected to the lower side of the electron beam emitting means 13 along the funnel 14. The second degaussing coil 16b, which has a substantially planar shape and a substantially quadrangular shape,
From below the electron beam emitting means 13, along the funnel 14, pass through the lower corner of the explosion-proof band 15, pass under the explosion-proof band 15, pass through the other lower corner of the explosion-proof band 15, and along the funnel 14. The electron beam emitting means 13 is connected to the lower side. First degaussing coil 16a
And the second degaussing coil 16b are vertically asymmetric, are formed of one coil, and are 2300AT.

[Explanation of FIGS. 1 and 2] The first degaussing coil 16a formed in a saddle shape in the first embodiment is provided with a second degaussing coil along the funnel 14 from above the electron beam emitting means 13. On the coil wire bent in the direction approaching 16b (in a saddle shape), pass through the upper corner portion of the explosion-proof band 15, pass through the upper portion of the explosion-proof band 15, pass through the other upper corner portion of the explosion-proof band 15, and enter the funnel 14. Along the coil wire bent in a direction approaching the second degaussing coil 16b (in a saddle shape), and is connected to the upper side of the electron beam emitting means 13. The explosion-proof band 15 of the first degaussing coil
The side passing through the upper corner of the upper side of the color selection electrode 20, and substantially parallel to the upper side of the color selection electrode 20,
It is arranged. The first degaussing coil 16a is disposed substantially parallel to the vertical side of the display panel 10 at the left and right corners.

The second degaussing coil 16b is arranged vertically symmetrically with respect to the electron beam emitting means 13 with respect to the first degaussing coil 16a. The second degaussing coil 16b formed in a saddle shape in the first embodiment is connected to the first degaussing coil 16b from below the electron beam emitting means 13 along the funnel 14.
a, passing through a coil wire bent in a direction approaching a (saddle shape), passing through a lower corner portion of the explosion-proof band 15, passing through a lower portion of the explosion-proof band 15, passing through another lower corner portion of the explosion-proof band 15, and forming a funnel. It passes along the coil wire bent (in a saddle shape) in a direction approaching the first degaussing coil 16 a along the line 14 and is connected to the lower side of the electron beam emitting means 13. The side of the second degaussing coil passing through the lower corner of the explosion-proof band 15 is disposed below the lower side of the color selection electrode 20 and substantially parallel to the lower side of the color selection electrode 20. . The second degaussing coil 16b is disposed substantially parallel to the vertical side of the display panel 10 at the left and right corners. The degaussing current of the first degaussing coil 16a and the second degaussing coil 16b is 2300AT. Further, the first degaussing coil and the second degaussing coil are disposed so as to be vertically opposed to each other.

[Description of FIGS. 3 and 4] The conventional degaussing coil shown in FIG. 13 and the degaussing coil of the first embodiment shown in FIGS. 1 and 2 are set on a 25-inch CRT, respectively.
FIG. 3 shows a comparison of the magnitude of the magnetization of the color selection electrode 20 as a numerical analysis result after performing the degauss operation, and FIG. 4 shows a comparison of the amount of beam movement. FIG. 3 and FIGS. 6, 8, and 10, which will be described later, show the amount by which the external magnetic field is weakened by the magnetic shield or the like. The larger the value, the greater the shielding effect and the less the effect of the external magnetic field. That is, it shows that the degaussing coil has a large degaussing effect. In the numerical analysis, the analysis region was divided into about 70,000 finite elements in consideration of the hysteresis magnetic characteristics of the magnetic material by the curling model theory, and a nonlinear magnetic field analysis was performed by a three-dimensional finite element method. The method of measuring the beam movement amount shown in FIG. 4 is based on the assumption that the external vertical magnetic field is constant at 0.35 gauss, and the external horizontal magnetic field (east-west direction and tube axis direction) is 0 or 0.3 gauss. Measure the amount. Each time a measurement is performed, degauss operation is performed by a degaussing coil using an attenuated alternating magnetic field. The measurement points are
This is a corner of the color selection electrode 20. This is because the beam movement amount is the largest in the corner portion.

As compared with the conventional substantially planar degaussing coil,
At least a part of the first and second degaussing coils of the present invention are each bent in a direction approaching the other degaussing coils. The degaussing coil of the present invention can generate a more efficient degaussing magnetic field in degauss operation. In FIG. 3, in the conventional degaussing coil, the shield effect of the external magnetic field occurs only in a very limited range. On the other hand, the degaussing coil of the present invention has a substantially uniform external magnetic field shielding effect over a wide area of the screen. Further, the degaussing coil of the present invention has a particularly large effect of shielding an external magnetic field in a portion near the center of the screen. Since the center of the screen often displays an important screen as compared to the peripheral part, it is important that the effect of shielding the external magnetic field in the part close to the center of the screen is large.

FIG. 4 is a graph showing changes in the trajectory of the electron beam due to the external magnetic fields of the east-west magnetic field and the tube axis magnetic field.
As shown in FIG. 4, in the display device of the present invention, in both the east-west magnetic field and the tube-axis magnetic field, the change in the trajectory of the electron beam is improved by about 25% compared to the conventional example, and the color shift is reduced. Is suppressed. 3 and 4 show that the degaussing magnetic field generated by the degaussing coil in the degauss operation of the display device using the degaussing coil according to the present invention has
This shows that the magnetic shield formed by the internal magnetic shield 12 flows more efficiently than the conventional example, and the effective magnetic permeability of the magnetic shield 12 can be increased.

Although the above-mentioned special effects of the present invention are clearly demonstrated by FIGS. 3 and 4, it is presumed that the above-mentioned special effects have occurred for the following reasons. A degaussing coil generates a magnetic field perpendicular to a plane defined by the coil as an edge. In the conventional example, a magnetic field generated by a substantially planar demagnetizing coil attached to the color selection electrode 20 at an angle close to a right angle flows substantially parallel to the color selection electrode 20. Therefore, the magnetic field passing through the color selection electrode 20 is small,
It is considered that the demagnetizing effect was small. In the degaussing coil of the present invention, at least a part of each of the first and second degaussing coils is bent in a direction approaching each other to each other. It is considered that the degaussing magnetic field generated by the degaussing coil in the bent portion passed through the color selection electrode assembly 11, and thereby a large demagnetization effect of the color selection electrode assembly 11 was obtained.

Further, since the first degaussing coil and the second degaussing coil are arranged vertically opposite to each other, the first degaussing coil and the second degaussing coil have the same shape. Therefore, the same parts can be used. As a result, the types of parts used can be reduced.
In addition, the cost of the degaussing coil can be reduced by using twice the degaussing coil of the same shape (the first degaussing coil and the second degaussing coil).

<< Embodiment 2 >> A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is an explanatory view showing the degaussing coil structure of the second embodiment. The display device of the second embodiment in FIG. 5 substantially extends along the left and right side surfaces of the funnel 14.
In addition, a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are disposed near the side surface of the color selection electrode 20 and substantially parallel to the left and right vertical sides of the color selection electrode 20. Thus, the third embodiment differs from the first embodiment. FIG. 6 shows the magnitude distribution of the magnetization of the color selection electrode 20, which is a numerical analysis result after the degauss operation is performed by setting the degaussing coil of the second embodiment shown in FIG. 5 on a 25-inch CRT. From FIG. 6, near the color selection electrodes 20 on the left and right side surfaces of the funnel 14,
In the degaussing coil according to the second embodiment, in which a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are disposed substantially parallel to the left and right vertical sides of the color selection electrode 20, a conventional example (FIG. 3) The magnitude of magnetization of the color selection electrode after degauss is larger than that of
It becomes uniform, the shielding effect of the external magnetic field is improved, the change in the trajectory of the electron beam due to the external magnetic field is suppressed, and the color shift is suppressed. FIG. 6 of the second embodiment shows that the degaussing coil has a greater degaussing effect than FIG. 3 of the first embodiment.

In the second embodiment, by disposing a part of the degaussing coil substantially parallel to the vertical side of the color selection electrode 20, it is arranged substantially parallel to the vertical side of the color selection electrode 20. Magnetic field generated by a part of the provided degaussing coil (generated perpendicular to the plane defined by the part of the degaussing coil)
Almost all pass through the color selection electrode 20. Thus, it is considered that the magnetic field passing through the color selection electrode 20 could be further uniformly and increased. Also, by disposing the first degaussing coil and the second degaussing coil substantially in parallel near the color selection electrodes on the left and right sides of the funnel, the magnetic field on the surface of the color selection electrodes can be strengthened ( The closer the plane defined by a part of the degaussing coil and the color selection electrode are, the stronger the magnetic field generated by the degaussing coil is.) The effect of shielding the external magnetic field is improved, and the trajectory of the electron beam due to the external magnetic field Is suppressed, color shift can be suppressed, and high image quality can be realized.

<< Embodiment 3 >> A third embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory view showing the degaussing coil structure of the third embodiment. In the display device of the third embodiment shown in FIG. 7, a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are arranged close to the color selection electrodes 20 on the left and right sides of the funnel 14. However, the present embodiment is different from the first embodiment shown in FIGS. FIG. 8 shows the magnitude distribution of the magnetization of the color selection electrode 20, which is a numerical analysis result after the degauss operation is performed by setting the degaussing coil of the third embodiment shown in FIG. 7 on a 25-inch CRT.

As shown in FIG. 8, in the third embodiment, a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are arranged close to the color selection electrodes 20 on the left and right sides of the funnel 14. In the degaussing coil, the magnitude of magnetization of the color selection electrode after degauss is large and uniform, the shielding effect of the external magnetic field is improved, and the change in the trajectory of the electron beam due to the external magnetic field is suppressed, as compared with the conventional example. Color shift is suppressed.

In the third embodiment, by disposing the first degaussing coil and the second degaussing coil close to each other,
Since a portion of the first degaussing coil parallel to the color selection electrode 20 and a portion of the second degaussing coil parallel to the color selection electrode 20 constitute a circuit similar to a closed loop parallel to the color selection electrode 20. Thus, a uniform and large magnetic field can be generated that passes over substantially the entire surface of the color selection electrode 20. Thus, it is considered that an excellent demagnetizing effect of the color selection electrode 20 could be obtained. As described above, the first demagnetizing coil and the second demagnetizing coil are located near the color selection electrodes on the left and right sides of the funnel.
By disposing the demagnetizing coils in close proximity to each other, the shielding effect of the external magnetic field is improved, the change in the trajectory of the electron beam due to the external magnetic field is suppressed, the color shift can be suppressed, and high image quality can be realized.

<< Embodiment 4 >> A fourth embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory view showing the degaussing coil structure of the fourth embodiment. The display device of the fourth embodiment shown in FIG. 9 is different from the first embodiment shown in FIGS. 1 and 2 in that the first degaussing coil 16a and the second degaussing coil 16b are formed by one coil. Different from the example. FIG. 10 shows the magnitude distribution of the magnetization of the color selection electrode 20 as a result of numerical analysis after the degaussing coil of Example 4 shown in FIG. 9 was set on a 25-inch CRT and subjected to a degauss operation.

The degaussing coil of the fourth embodiment is as shown in FIG.
A first degaussing coil 16a and a second degaussing coil 16b are provided near the color selection electrodes 20 on the left and right sides of the funnel 14.
Are arranged substantially parallel to each other, and the first degaussing coil 16a and the second degaussing coil 16b
Are formed by one coil. As shown in FIG. 10, the degaussing coil of the fourth embodiment can provide a shielding effect equivalent to that of the second or third embodiment. Thus, the degauss improves the shielding effect of the external magnetic field, suppresses the change in the trajectory of the electron beam due to the external magnetic field, suppresses color shift, and realizes high image quality. In addition, the cost can be reduced by reducing the conventional two degaussing coils to one degaussing coil.

<< Embodiment 5 >> A fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory view showing the degaussing coil structure of the fifth embodiment. In the display device of the fifth embodiment in FIG. 11, a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are disposed on the left and right sides of the funnel 14 above and below the color selection electrode 20. The second embodiment differs from the first embodiment shown in FIGS. 1 and 2 in that it is disposed forward of a plane defined by the sides. Thus, the first degaussing coil 16a and the second degaussing coil 16a
The degaussing coil according to the fifth embodiment in which a part of b is disposed forward on the side surface of the funnel 14 can obtain a degaussing effect similar to that of the second embodiment (FIG. 6) (not shown). Therefore, compared to the conventional example, the magnitude of magnetization of the color selection electrode after degauss is large and uniform, the shielding effect of the external magnetic field is improved, the change of the trajectory of the electron beam due to the external magnetic field is suppressed, and the color shift Is suppressed.

In general, the magnetic field generated by the degaussing coil is considered to be stronger as the plane is closer to the plane defined by the degaussing coil as an edge, and to be weaker as the distance from the plane increases. Referring to FIG. 2, the upper and lower ends of the color selection electrode 20 are close to the plane defined by the degaussing coil, but the center of the color selection electrode 20 is far from the plane defined by the degaussing coil. FIG. 3 shows that the center of the color selection electrode 20 is
This shows that the demagnetizing effect is smaller than the upper and lower ends.
FIG. 11 shows that the first and second degaussing coils 16a and 16b are partially exposed to the front so that the color selection electrode 2
0, a plane defined by the degaussing coil,
Is reduced, and it is considered that the improved demagnetizing effect is obtained in the fifth embodiment as compared with the first embodiment.

In the above embodiment, the case of a color selection electrode structure made of a Ni-Fe material has been described as an example, but the present invention is also applied to a display device of a color selection electrode structure made of another magnetic material such as an iron material. it can. Further, in the above embodiment, the case where the internal magnetic shield is made of SPCC is described as an example.
The present invention is also applicable to a display device having an internal magnetic shield made of another magnetic material such as a permalloy material. In the above embodiment, a 25-inch color television has been described as an example.
The present invention can also be applied to display devices using other inch-size cathode ray tubes. Further, in the above-described embodiment, the color television has been described as an example, but the present invention is not limited to this.
It can be applied to a display device using a cathode ray tube, such as a T display monitor.

[0040]

According to the present invention, in the degauss operation,
The degaussing magnetic field generated by the degaussing coil flows efficiently through the magnetic shield formed by the color selection electrode assembly and the internal magnetic shield. Thereby, the effective magnetic permeability of the magnetic shield can be increased, the shielding effect of the external magnetic field is improved, the change in the trajectory of the electron beam due to the external magnetic field is suppressed, the color shift can be suppressed, and high image quality can be realized. That is, an advantageous effect can be obtained. In particular, in the color selection electrode 20,
The advantageous effect of making the external magnetic field shield effect higher and more uniform than the conventional example is obtained. Further, according to the invention of claim 3 and the like, the advantageous effect that the cost of the degaussing coil can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a display device according to a first embodiment.

FIG. 2 is an explanatory view showing a structure of a degaussing coil according to the first embodiment.

FIG. 3 is a magnetization distribution diagram as a result of numerical analysis showing a degauss effect of each of the degaussing coils of the conventional example and the first embodiment.

FIG. 4 is a graph showing respective beam movement amounts due to an external magnetic field in the conventional example and the first embodiment.

FIG. 5 is an explanatory view showing the structure of a degaussing coil according to a second embodiment.

FIG. 6 is a magnetization distribution diagram as a result of numerical analysis showing a degauss effect by the degaussing coil of the second embodiment.

FIG. 7 is an explanatory view showing the structure of a degaussing coil according to a third embodiment.

FIG. 8 is a graph showing magnetization distribution as a result of numerical analysis showing the effect of degauss by the degaussing coil of the third embodiment.

FIG. 9 is an explanatory view showing the structure of a degaussing coil according to a fourth embodiment.

FIG. 10 is a graph showing magnetization distribution as a result of numerical analysis showing the degauss effect of the degaussing coil of the fourth embodiment.

FIG. 11 is an explanatory view showing the structure of a degaussing coil according to a fifth embodiment.

FIG. 12 is a perspective view showing a configuration of a conventional display device.

FIG. 13 is an explanatory view showing the structure of a conventional degaussing coil.

FIG. 14 is an explanatory view showing a shadow mask which is a color selection electrode structure of a CRT.

FIG. 15 is an explanatory view showing a tension mask which is a color selection electrode structure of a CRT.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Display panel 11 Color selection electrode structure 11a Shadow mask which is a color selection electrode structure 11b Tension mask which is a color selection electrode structure 12 Internal magnetic shield 13 Electron beam emission means 14 Funnel 15 Explosion-proof band 16a First degaussing coil 16b Second Demagnetizing coil 17 Electron beam orbit 20 Color selection electrode 21 Frame 21a Angle 21b as first frame 21b Arm as second frame

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroto Inoue 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Term (reference) 5C060 CM02 CN05 JA00

Claims (9)

[Claims] 1. A display panel having a phosphor screen, an electron beam emitting unit for emitting an electron beam toward the display panel, a color selection electrode having a hole for passing the electron beam, and the color selection electrode A frame that supports the electron beam, an internal magnetic shield that shields the electron beam from magnetism, and a funnel that is joined to the display panel so as to cover the electron beam emitting unit, the color selection electrode, the frame, and the internal magnetic shield. A first and a second degaussing coil disposed substantially along the funnel, wherein the first degaussing coil is located above an upper side of the color selection electrode and the color A first side disposed substantially parallel to an upper side of the selection electrode, wherein the second degaussing coil is located below a lower side of the color selection electrode and substantially below a lower side of the color selection electrode; Has a second side disposed in parallel, and at least a part of the first and second degaussing coils are each bent in a direction approaching another degaussing coil. A display device characterized by the above-mentioned. 2. At least two sides of each of the first and second degaussing coils are substantially along a side surface of the funnel and parallel to left and right vertical sides of the color selection electrode. The display device according to claim 1, wherein the display device is disposed. 3. The first and the second degaussing coils,
The display device according to claim 1, further comprising: symmetrically arranged with respect to each other. 4. The first degaussing coil has a third side disposed substantially along a side surface of the funnel, and the second degaussing coil is disposed substantially along a side surface of the funnel. The display device according to claim 3, further comprising a fourth side provided, wherein the third side and the fourth side are disposed substantially in parallel with each other. 5. The display device according to claim 4, wherein the third side and the fourth side are further provided near a side surface of the color selection electrode. 6. The display device according to claim 4, wherein the third side and the fourth side are further arranged close to each other. 7. The method according to claim 1, wherein the first degaussing coil and the second degaussing coil are formed of a single coil. Display device. 8. At least a part of each of the first degaussing coil and the second degaussing coil is disposed forward of a plane defined by the first side and the second side. The display device according to claim 1, wherein the display is performed. 9. The display device according to claim 1, wherein at least one side of each of the first degaussing coil and the second degaussing coil is disposed on an explosion-proof band.