JP2001258043A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which uses a cathode-ray tube that can sufficiently suppress color smear and realize considerably high image quality. SOLUTION: The display device consists of a cathode-ray tube, having a color selection electrode 20 fixed to a frame 21 with a tension added thereto and having an internal magnetic shield 12, that magnetically shields an electron beam and of a degaussing coil 16 placed to a funnel 14 of the cathode-ray tube. The degaussing coil consists of a couple of 1st and 2nd degaussing coils 16a and 16b placed vertically, and the 1st and 2nd degaussing coils have first parallel part 16a-1 and 16b-1, extended in parallel along an upper side or lower side of the color selection electrode, 2nd parallel parts 16a-2 and 16b-2 that extend in parallel with sides, and sneak path parts 16a-3 and 16b-3, that take a sneak path toward the side face of the funnel 14 and the sneak paths are brought into contact with 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. ), Particularly to a display device such as a television.

[0002]

2. Description of the Related Art Generally, in a CRT, an electron beam emitted from an electron beam emitting means such as an electron gun passes through a pore of a color selection electrode and lands on a phosphor.
Emit red, green, or blue light.

Hereinafter, a display device including a conventional CRT, for example, a color television will be described with reference to FIGS. 9 to 12. Each figure shows only those structures that are deeply related to changes in the trajectory of the electron beam due to the external magnetic field of the color television. In FIG. 9, a conventional color television has a color selection electrode including a color selection electrode 20 and a frame 21 between a display panel 10 having a phosphor screen and an electron gun 13 for emitting an electron beam toward the display panel 10. There is a structure. Also,
The color television has the color selection electrode assembly and the internal magnetic shield 1.
2 is provided.
Further, the color television includes a funnel 14, which is joined to the display panel 10 so as to cover the electron gun 13 and the external magnetic field shield structure 18, a neck 19, an explosion-proof band 15, and a degaussing coil 16 disposed on the funnel 14. Have.

FIG. 10 is a side view of the conventional display device shown in FIG. 9, which is housed inside the CRT and cannot be normally seen. The side surfaces of the color selection electrode 20, the angle 21a, and the upper and lower internal magnetic shields 12 are shown. FIG. 3 is a side view illustrating a positional relationship between a degaussing coil 16 and an external magnetic field shield structure 18 with a projection position shown in a side view of the display device.

[0005] As shown in FIG. 11, a typical example of a color selection electrode structure including a color selection electrode 20 and a frame 21 is a shadow mask structure 11a. The shadow mask structure 11a is one in which a color selection electrode 20 having a large number of pores formed therein is curved into a predetermined shape by pressing and fixed to a frame 21 by welding. When trying to flatten the screen of a CRT, it is necessary to make this shadow mask (color selection electrode) close to flat, and the amount of deformation due to thermal expansion of the shadow mask caused by the temperature rise due to the collision of the electron beam is the shadow mask. Becomes closer to flat, and the function may be impaired due to a shift in the positional relationship with the phosphor.

As a solution to this, as shown in FIG.
A so-called tension mask structure 11 in which a color selection electrode 20 having a large number of pores formed thereon is fixed to a frame 21 with tension applied only in the vertical direction of the screen.
A scheme using b has been proposed. According to this method,
Tension mask structure 11b with tension applied
Absorbs elongation of thermal expansion caused by electron beam collision and prevents deformation.

However, when an external magnetic field such as terrestrial magnetism is received while the electron beam reaches the fluorescent screen of the display panel 10 from the electron gun 13, the electron beam receives Lorentz force, and its trajectory changes, and the original landing changes. A part or all of the beam spot lands on a point shifted from the point and strikes a phosphor different from the phosphor that should originally emit light, causing a so-called color shift.

In order to suppress the color shift, an internal magnetic shield 12 is provided, and an external magnetic field shield structure 18 is constituted by the internal magnetic shield 12 and the color selection electrode structure. Color shift is suppressed.

The external magnetic field shield structure is, for example, 36% N
Angle 21a as first frame made of i-Fe material
And a tension mask structure 11b composed of, for example, a second frame arm 21b made of 42% Ni-Fe material and a color selection electrode 20 made of 36% Ni-Fe material, for example, and an interior made of Fe material, for example. Magnetic shield 1
And 2.

Further, a degauss operation is performed to improve the magnetic shielding effect. The degauss operation means that when the external magnetic field shield structure 18 including the color selection electrode structure such as the tension mask structure 11b is considered as a magnetic circuit, an attenuated alternating magnetic field is applied to the external magnetic field shield structure 18 in the presence of geomagnetism as a bias magnetic field. This operation is performed by supplying an attenuated alternating current to the first degaussing coil 16a and the second degaussing coil 16b.

An approximately quadrangular first degaussing coil 16a of the degaussing coil passes above the color selection electrode 20, passes through a corner above the color selection electrode 20, reaches a funnel, and follows an electron gun along the funnel 14. It passes through the lower part near the neck surrounding the neck 13, along the funnel 14 on the opposite side surface, through the upper corner of the color selection electrode 20, and above the color selection electrode 20. The substantially quadrangular second degaussing coil 16b passes under the color selection electrode 20, passes through the corner below the color selection electrode 20, reaches the funnel, and follows the ridge line of the funnel 14 into the electron gun 13b.
Through the lower part near the neck 19 surrounding the funnel 14 along the ridge line of the funnel 14 on the opposite side surface.
Through the lower corner of the color selection electrode 20. The first degaussing coil 16a and the second degaussing coil 16b are formed of a single connected coil, are arranged in a vertically asymmetrical eight-shape, are connected to a power supply circuit, and have a magnetomotive force of 1000 to 1000. It is about 4000AT.

Here, the "ridge line" of the funnel 14 refers to a ridge line from the corner of the rectangular display panel to the neck of the funnel. In this case, the ridge line may not be clear because the funnel cross section becomes circular as approaching the neck side, but it is assumed that the ridge line extends from the corner of the rectangular display panel.

In this degauss operation, since the terrestrial magnetism is applied as a bias magnetic field, after the degauss operation, the external magnetic field shield structure 18 including the tension mask structure 11b is more likely to be positioned in the direction of the terrestrial magnetism as the bias magnetic field than in the case where only the terrestrial magnetism is used. Large magnetization is also generated. Due to the magnetization generated in the direction of the terrestrial magnetism, a magnetic field for canceling the terrestrial magnetism is generated inside the external magnetic field shield structure 18. As a result, a magnetic shielding effect is exhibited, a change in the trajectory of the electron beam due to an external magnetic field can be suppressed, and color shift can be suppressed. Therefore, of the magnetic fluxes generated by the degaussing coil 16, by increasing the magnetic flux flowing to the external magnetic field shield structure 18 including the tension mask structure 11b,
It is important to generate enough magnetization to cancel the terrestrial magnetism after the degauss operation in order to reduce the influence of the terrestrial magnetism of the electron beam.

[0014]

However, in the tension mask structure 11b as described above, the color selection electrode 2 is not provided.
Frame 21 which applies tension to the color selection electrode 2
And an arm 21 as a second frame supporting the angle 21a.
Therefore, there is a portion without a geomagnetic shield in the side direction due to the structure. Therefore, arm 2
The horizontal magnetic field component of terrestrial magnetism, which is an external magnetic field in the side direction of 1b and the tube axis direction of the CRT, is not sufficiently shielded.
Further, since the color selection electrode 20 is supported in a state where tension is applied, the magnetic permeability is reduced due to magnetostriction. Further, the magnetic flux generated by the conventional demagnetizing coil which is arranged vertically apart from each other and arranged in an up / down asymmetrical figure eight shape flows non-uniformly into the tension mask structure 11b having a small magnetic permeability. In some cases, a part of the generated magnetic flux did not effectively flow to the tension mask structure 11b.

The demagnetizing coil of the conventional example shown in FIG. 9 is set on a 25-inch CRT, and the magnitude of the magnetization in the color selection electrode 20 after the degauss operation is numerically analyzed in detail in the second embodiment. As a result, FIG. 5A shows magnetization generated in the color selection electrode 20 after the degauss operation by the degauss operation using the conventional degaussing coil. As shown in FIG. 5A, since the magnetization in the color selection electrode 20 is not sufficient, the horizontal magnetic field component of the terrestrial magnetism is not sufficiently shielded. Therefore, the change of the trajectory of the electron beam due to the horizontal magnetic field component cannot be sufficiently suppressed, and there is a problem that a color shift occurs.

Accordingly, in view of the above problems, the present invention enhances the magnetic shielding effect by sufficiently magnetizing the color selection electrode by degauss operation, and can sufficiently suppress color misregistration as compared with the related art, thereby realizing extremely high image quality. It is an object of the present invention to provide a display device using a CRT that can be used.

[0017]

The above object can be attained by the following present invention.

That is, the display device of the present invention comprises a cathode ray tube having a color selection electrode fixed to a frame under tension, an internal magnetic shield for magnetically shielding an electron beam, and a funnel of the cathode ray tube. A degaussing coil provided, wherein the degaussing coil comprises a pair of upper and lower first and second degaussing coils, and the first and second degaussing coils are respectively provided with the color A first parallel portion extending substantially parallel along an upper side or a lower side of the selection electrode, and a first parallel portion extending substantially parallel along both sides of the color selection electrode from both ends of the first parallel portion. A second parallel portion, and a wraparound portion extending from an end of the second parallel portion to the side surface of the funnel, wherein a portion in contact with the wraparound portions of the first and second degaussing coils is provided. And that It is that the display device.

Here, at the time of the degauss operation, the first and second degaussing coils are used as a magnetic flux generation source, and the external magnetic field shield structure including the color selection electrode, the frame, and the internal magnetic shield is considered as a magnetic circuit. In this case, as described above,
A first parallel portion extending substantially parallel to the first and second degaussing coils along the upper side or lower side of the color selection electrode, respectively;
A second parallel portion extending substantially in parallel from both ends of the first parallel portion along the side of the color selection electrode; and a wraparound wrapping around the side surface of the funnel from the end of the second parallel portion. By providing a portion where the first and second degaussing coils are in contact with each other in the wraparound portion, leakage of magnetic flux between the upper and lower coils is substantially eliminated, and the interlinking surface of the degaussing coil and the internal magnetic shield are provided. And the magnetic flux flowing parallel to the internal magnetic shield increases along the internal magnetic shield because the cross-sectional area of the linkage surface of the degaussing coil perpendicular to the internal magnetic shield increases. As a result, of the magnetic flux generated by the demagnetizing coil, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the external magnetic field shield structure. For this reason, in the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and 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 is reduced. The displacement can be sufficiently suppressed.

Here, the "linkage surface" of the degaussing coil refers to a curved surface of which the magnetic flux component penetrating the curved surface is composed only of a perpendicular component of the curved surface, out of the curved surfaces having the degaussing coil as an outer periphery. The side surface shape of the degaussing coil in the side view explanatory diagram of (a) corresponds to the shape seen from the side where the outer circumference of the interlinking surface overlaps.

Here, the term "contact with each other" means not only the case where the members are in physical contact with each other but also the case where the magnetic flux leakage from the upper and lower coils is substantially negligible. In addition, any structure may be used as long as it makes contact once or more, and a configuration in which contact is made a plurality of times may be employed.

Further, the display device according to the present invention is the display device, wherein the portions in contact with each other are provided near the left and right side surfaces of the color selection electrode.

As described above, by providing the portions of the first and second demagnetizing coils that come into contact with each other in the wraparound portions near the left and right side surfaces of the color selection electrode,
The magnetic flux leaking between the upper and lower degaussing coils can be substantially eliminated. Also, the inclination between the linkage surface of the degaussing coil and the internal magnetic shield increases, and the cross-sectional area of the linkage surface of the degaussing coil perpendicular to the internal magnetic shield increases, so that the magnetic flux flowing parallel to the internal magnetic shield increases. . As a result, of the magnetic flux generated by the demagnetizing coil, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the external magnetic field shield structure. For this reason, in the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and 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 is reduced. The displacement can be sufficiently suppressed.

Further, in the display device according to the present invention, the frame may support the first side of the color selection electrode in a state where tension is applied to the first frame, and the frame may apply tension to the color selection electrode. The display device comprises: a second frame supporting the first frame.

As described above, the first frame for supporting the edge of the color selection electrode with tension applied thereto and the second frame for supporting the first frame such that tension is applied to the color selection electrode.
By adopting the frame structure composed of the frame, the cross-sectional area perpendicular to the vertical direction along the magnetic flux of the second frame can be reduced, so that the magnetic resistance is large, and the second frame of the magnetic flux generated from the upper and lower degaussing coils The demagnetizing magnetic field is effectively applied to the color selection electrode because the magnetic flux flowing through the color selection electrode increases without increasing the magnetic flux flowing through the color selection electrode.
For this reason, after the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure including the color selection electrode, the magnetic shielding effect increases, and the orbital change of the electron beam due to the horizontal external magnetic field is sufficiently increased. Restrained,
Color shift can be sufficiently suppressed.

In the display device of the present invention, the explosion-proof band provided has a relative magnetic permeability of 2,000 or more and 15,000 or more.
In addition to the following, the first and second degaussing coils each include a portion in which the first parallel portion or the second parallel portion includes a portion disposed on the explosion-proof band. The display device.

As described above, the explosion-proof band has a relative magnetic permeability of 20.
A high permeability of not less than 00 and not more than 15000 is provided, and is disposed on a high permeability explosion-proof band in each of the first and second parallel portions of the first and second degaussing coils. By providing the portion, the magnetic circuit including the tension mask structure can further include an explosion-proof band having a high magnetic permeability, and of the magnetic flux generated from the demagnetizing coil, the magnetic flux flowing through the magnetic circuit increases, so that the demagnetizing The magnetic field is effectively applied to the external magnetic shield structure. For this reason, after the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed. The displacement can be sufficiently suppressed.

Further, in the display device according to the present invention, the color selection electrode is provided in a region surrounded by the explosion-proof band.

As described above, since the color selection electrode is provided in the area surrounded by the explosion-proof band serving as the core of the degaussing coil, the magnetic circuit including the tension mask structure further includes the explosion-proof band having a high magnetic permeability. Therefore, of the magnetic flux generated by the degaussing coil, the magnetic flux flowing through the magnetic circuit increases, and the degaussing magnetic field is effectively applied to the external magnetic field shield structure. For this reason, after the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed. The displacement can be sufficiently suppressed.

Further, the display device of the present invention is characterized in that the first degaussing coil and the second degaussing coil have a flat cross section at a portion provided on each of the explosion-proof bands. The display device described above.

As described above, by forming the cross sections of the first and second degaussing coils disposed on the explosion-proof band to be flat, the mounting of the degaussing coil is simplified, and the displacement of the degaussing coil is reduced. After the degauss operation, a sufficiently large magnetization is generated in the external magnetic field shield structure to cancel the terrestrial magnetism, the magnetic shielding effect increases, and the change in the trajectory of the electron beam due to the horizontal external magnetic field is sufficiently suppressed. And color shift can be sufficiently suppressed.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to facilitate understanding of the present invention, the present invention will be described below with reference to embodiments. Each of the drawings shows only structures that are deeply related to changes in the trajectory of the electron beam due to the external magnetic field of the color television according to the embodiment. The display device is a color television having a CRT.

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the color television of the present embodiment includes a color selection electrode assembly and an internal magnetic shield 12 between a display panel 10 having a phosphor screen and an electron gun 13 for emitting an electron beam toward the display panel 10. An external magnetic field shield structure 18 is formed. Further, a funnel 14 joined to the display panel 10 so as to cover the electron gun 13 and the external magnetic field shield structure 18, a neck 19, and a funnel 14
And a first degaussing coil 16a and a second degaussing coil 16b arranged above and below.

The external magnetic field shield structure has, for example, a thickness of 1.
An angle 21a as a first frame made of a 4% 36% Ni-Fe material and, for example, a 1.4% thick 42% N
Arm 21b as a second frame made of i-Fe material
And a tension mask structure 11b which is a color selection electrode structure composed of a color selection electrode 20 made of 36% Ni-Fe material having a thickness of 0.1 mm, for example, and a thickness of 0.15
mm of an internal magnetic shield 12 made of an Fe material.

FIG. 2 (a) shows the display device according to the first embodiment shown in FIG. 1, which is housed inside the CRT and cannot be viewed normally, the color selection electrode 20, the angle 21a, and the upper and lower internal magnets. FIG. 3 is an explanatory side view showing a positional relationship between a degaussing coil 16 and an external magnetic field shield structure 18 with a side projection position of a shield 12 shown in a side view of the display device. FIG. 2B is a rear view showing the disposition state of the degaussing coil.

The edge of the color selection electrode 20 is supported with a tension of about 80 to 160 kg so that the color selection electrode 20 is made almost flat to make the screen of the CRT flat.
Thereby, the elongation of the increased thermal expansion is absorbed, and the deformation of the color selection electrode 20 can be prevented. However, the relative permeability, which was about 500 before the tension was applied, has been reduced to about 200 by the application of the tension, and the magnetic flux is less likely to flow than when supported without tension, canceling the geomagnetism. However, it is hardly magnetized.

As shown in FIGS. 1, 2 (a) and 2 (b),
The first degaussing coil 16a formed in a saddle shape is color-sorted from an end of the first parallel portion from a first parallel portion 16a-1 extending substantially parallel along the upper side of the color selection electrode 20. The funnel 1 extends from an end of the second parallel portion 16a-2 to a second parallel portion 16a-2 extending substantially in parallel along the side of the electrode 20.
4 from the wrap-around portion 16a-3 wrapping around the side surface of the funnel 14 on the opposite side via the upper side near the neck 19.
4 to the second parallel portion 16a-5 extending along the side of the color selection electrode 20 from the end of the second parallel portion 16a-5 in parallel along the upper side of the color selection electrode 20. It leads to the extending first parallel portion 16a-1. Also, the first
The degaussing coil 16 a is disposed near the color selection electrode 20, for example, on the neck side of the color selection electrode 20 by 3 mm above the display panel 10. The first degaussing coil 16a and the second degaussing coil 16b are vertically symmetrically arranged.
6a and the second degaussing coil 16b are disposed in contact with each other on the left and right side surfaces in the wraparound portion from the end of each second parallel portion, are connected to a power supply circuit, and have a magnetomotive force of 2300AT.

The shape of the degaussing coil is the first and the second.
The degaussing coil includes a first parallel portion extending substantially parallel along an upper side or a lower side of the color selection electrode, and a first parallel portion extending from both ends of the first parallel portion in parallel along a side of the color selection electrode. A second parallel portion that is present and a wraparound portion that wraps around the side surface of the funnel are provided. If the wraparound portion is provided with portions that are in contact with each other, besides a saddle shape,
Boat shape and other shapes can be adopted. In this case, it is desirable that each parallel portion includes a straight line portion.

The term "near" the color selection electrode 20 in the present invention means a portion within the range of the distance between the color selection electrode 20 and the end of the frame in the tube axis direction.

The electron beam emitted from the electron gun 13 is
The light passes through the pores of the color selection electrode 20 and lands on the phosphor of the display panel 10 to emit any one of red, green, and blue.

Each of the first and second degaussing coils has a first parallel portion extending in parallel along the upper side or lower side of the color selection electrode, and side edges of the color selection electrode from both ends of the first parallel portion. By providing a second parallel portion extending in parallel along the axis and a wraparound portion wrapping around the side surface of the funnel, and providing a portion in contact with each other in the wraparound portion, thereby providing a linkage surface of the degaussing coil. And the inclination of the internal magnetic shield increases, and the cross-sectional area of the linkage surface of the degaussing coil perpendicular to the internal magnetic shield increases, so that the magnetic flux flowing parallel to the internal magnetic shield increases. As a result, of the magnetic flux generated by the demagnetizing coil, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the external magnetic field shield structure. For this reason, after the degauss operation, a sufficiently large magnetization is generated in the external magnetic field shield structure to cancel the terrestrial magnetism, the magnetic shielding effect increases, and 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 occurs. Can be sufficiently suppressed, and high image quality can be realized.

Here, the first and second degaussing coils 16a,
16b, the color selection electrodes 2 from both ends of the first parallel portion
A second parallel portion extending in parallel along the side of 0;
Provide a wrap around part on the side of the funnel,
In order to further clarify the effect of providing the portions that are in contact with each other in the wraparound portion, the first and second degaussing coils 16a and 16b are wrapped around the inner side of the ridge line of the funnel 14; A reference example in which the second parallel portion extending in parallel along the side of the electrode 20 is not provided, and the wraparound portion is not provided with portions that are in contact with each other will be described below.

Reference Example As shown in FIGS. 8A and 8B, the first degaussing coil 16a formed in a saddle shape extends in parallel along the upper side of the color selection electrode 20. From one end of the parallel portion 16a-1, passing through the upper corner of the color selection electrode 20, and passing around the side of the second frame 21b inside the ridge line of the funnel 14, from the wraparound portion 16a-2, the electron gun 13 Portion 16 wrapping around the side of the second frame 21b inside the ridgeline of the funnel 14 on the opposite side via the upper side near the neck 19 surrounding the neck 19
From a-3, it passes through the upper corner of the color selection electrode 20 and leads to the first parallel portion 16a-1 extending in parallel along the upper side of the color selection electrode 20. The first degaussing coil 16a and the second degaussing coil 16b are vertically symmetrically disposed above or below the color selection electrode 20, near the color selection electrode 20, for example, on the 3 mm neck side of the color selection electrode 20. Are connected to a power supply circuit, and the magnetomotive force is 2300AT.

An explosion-proof band 15 'having a high magnetic permeability is provided so as to surround the color selection electrode 20, and a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are respectively provided with the explosion-proof band 15' having a high magnetic permeability. Located above

The upper and lower first and second degaussing coils 16a, 1
The demagnetizing coil 16 b is provided on the inner side surface of the funnel 14 on the inner side from the ridge line of the funnel 14, and is provided on the explosion-proof band 15 having high magnetic permeability.
The inclination between the intersecting surface of the demagnetizing coil 16 and the internal magnetic shield 12 increases, and the cross-sectional area of the intersecting surface of the degaussing coil 16 perpendicular to the internal magnetic shield 12 increases. Increase. As a result, a large amount of magnetic flux generated from the degaussing coil 16 in the degauss operation flows into the external magnetic field shield structure 18 constituted by the color selection electrode structure and the internal magnetic shield 12. For this reason, the magnetization on the surface of the color selection electrode after degauss is
As shown in FIG. 6, the result of a numerical analysis described later shows that a sufficiently large magnetization is generated, and FIG.
As compared with (a), the magnetic shielding effect is improved in the external magnetic field shielding structure including the color selection electrodes,
Color misregistration is suppressed as compared with the conventional example, and high image quality can be realized.

Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. The display device according to the second embodiment shown in FIGS. 3 and 4 differs from the first embodiment in that an explosion-proof band 15 having a high magnetic permeability is provided so as to surround the tension mask structure 11b. The high magnetic permeability referred to in the present invention means that the relative magnetic permeability is
2000 which is 1.3 to 10 times that of conventional explosion-proof bands
The above means 15,000 or less.

The explosion-proof band having high magnetic permeability has a width of 5% to 20% of a diagonal dimension of the display panel and is disposed so as to surround the color selection electrode. In a 25-inch CRT, the diagonal dimension is 635 mm, and the explosion-proof band has a width of, for example, 55 m.
m, made of an Fe material having a thickness of 1.0 mm, and the explosion-proof band has a relative magnetic permeability of about 3000. The degaussing coil is 30 mm from the display panel side of the explosion-proof band and 25 m from the neck side.
m.

FIG. 8 shows the conventional degaussing coil shown in FIG. 9 and the degaussing coil of the second embodiment (Example 2) shown in FIG.
5 (a), (b) and FIG. 5 (b) show the results obtained by setting the demagnetizing coils of the reference example shown in FIG. 6 is shown. In the numerical analysis, a non-linear magnetic field analysis is performed by a three-dimensional finite element method in consideration of a hysteresis magnetic characteristic of a magnetic material by a curling model theory, and the analysis region is divided into about 70,000 finite elements.

Each of the first and second degaussing coils has a first parallel portion extending in parallel along the upper side or lower side of the color selection electrode, and a side of the color selection electrode from both ends of the first parallel portion. A second parallel portion extending in parallel along the side, and a wraparound portion wrapping around a side surface inside the upper and lower ridge lines of the funnel are provided. By arranging the first parallel portion and the second parallel portion of each of the 1 degaussing coil and the 2nd degaussing coil on an explosion-proof band having high magnetic permeability, magnetic flux leakage between upper and lower coils is substantially eliminated, and degaussing is performed. The inclination between the interlinking surface of the coil and the internal magnetic shield increases, and the cross-sectional area of the interlinking surface of the degaussing coil perpendicular to the internal magnetic shield increases, so that the magnetic flux flowing parallel to the internal magnetic shield increases. As a result, of the magnetic flux generated by the demagnetizing coil, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, and the magnetic flux flowing to the color selecting electrode increases, so that the demagnetizing magnetic field is effectively applied to the color selecting electrode. . Therefore, after the degauss operation, as shown in FIG. 5B, a larger magnetization is generated in the color selection electrode than in FIG. 5A in the case of the conventional degaussing coil. Furthermore, by providing parts that are in contact with each other in the wraparound part,
A larger magnetization is generated than in FIG. 6 in the case of the reference example. For this reason, after degauss, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure including the color selection electrode, the magnetic shielding effect increases, and the orbital change of the electron beam due to the horizontal external magnetic field is sufficiently increased. Color shift can be suppressed sufficiently.

Third Embodiment A third embodiment of the present invention will be described with reference to FIG.
In the display device according to the third embodiment shown in FIG. 7, the first degaussing coil and the second degaussing coil are each formed flat at the first parallel portion provided on the explosion-proof band according to the second embodiment. Different from form.

As described above, the first parallel portion (1 in FIG. 7A) disposed on the explosion-proof band of the first and second degaussing coils.
By making the coil cross section flat (FIG. 7B) at the portion surrounded by the dotted line in FIG. 6A, the mounting of the degaussing coil can be simplified, and the degaussing magnetic field can be effectively prevented while preventing the degaussing coil from being displaced. Applied to the tension mask structure. For this reason, in the degauss operation by the degaussing coil, a sufficiently large magnetization for canceling the terrestrial magnetism is generated in the tension mask structure, and the magnetic shielding effect 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.

In the above description of the present invention, a case has been described in which the present invention is applied to a tension mask type in which a color selection electrode having a large number of pores is fixed to a frame with tension applied only in the vertical direction of the screen. However, the present invention is not limited to this, and a method of fixing a color selection electrode having a large number of pores in a state where tension is applied in both the vertical direction and the horizontal direction of the screen and a method called an aperture grille The present invention can be applied to all methods of fixing the color selection electrode to the frame with tension applied thereto, such as a method of fixing the strip to the frame with tension applied in the vertical direction of the screen, and has the same effect. .

In the case where the screen of the color selection electrode is fixed to the frame in a state where tension is applied to the screen in the left and right direction, the degaussing coil may be arranged on either side of the tube axis from the degaussing coil. In this case, the same effect as the present invention can be obtained.

In the above embodiment, Ni-Fe
Although the case of a tension mask made of a material has been described as an example, the present invention can be applied to a display device using a tension mask made of another magnetic material such as an Fe material.

In the above embodiment, the case of the internal magnetic shield made of Fe material has been described as an example. However, the present invention can be applied to a display device using an internal magnetic shield made of another magnetic material such as a permalloy material.

In the above embodiment, the case of the explosion-proof band made of Fe material has been described as an example.
It can be applied to a display device using an explosion-proof band made of another magnetic material such as a material.

In the above embodiment, a 25-inch color television has been described as an example, but the present invention can be applied to other display devices using an inch-size cathode ray tube.

In the above embodiment, a color television was described as an example. However, the present invention is not limited to this.
It can be applied to other display devices using a cathode ray tube, such as a T display monitor.

[0059]

According to the display device using the cathode ray tube of the present invention, the first and second degaussing coils have a first parallel portion extending substantially in parallel along the upper and lower sides of the color selection electrode; It has a second parallel portion extending substantially parallel from both ends of the one parallel portion along the side of the color selection electrode, and a wrap portion wrapping around the side surface of the funnel from the end of the second parallel portion. At the same time, by providing a portion in contact with each other in the wraparound portion of the first and second degaussing coils, leakage of magnetic flux between the upper and lower degaussing coils is almost eliminated, and the linkage surface of the degaussing coil and the internal magnetic shield Becomes larger, and the cross-sectional area of the linkage surface of the degaussing coil perpendicular to the internal magnetic shield increases, so that the magnetic flux flowing in parallel along the internal magnetic shield increases. As a result, of the magnetic flux generated by the demagnetizing coil, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the external magnetic field shield structure.

Therefore, by performing the degauss operation in the presence of the terrestrial magnetism as the bias magnetic field, after the degauss operation, a larger magnetization is generated in the external magnetic field shield structure including the tension mask structure in the direction of the terrestrial magnetism as the bias magnetic field. However, a magnetic field for canceling geomagnetism is generated inside the external magnetic field shield structure. As a result, the magnetic shielding effect is increased, the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, the color shift can be sufficiently suppressed, and high image quality can be realized.

[Brief description of the drawings]

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

FIGS. 2A and 2B are explanatory side views showing a positional relationship between a degaussing coil and an external magnetic field shield structure according to the first embodiment, and a rear view showing an arrangement state of the degaussing coil.

FIG. 3 is a perspective view illustrating a configuration of a display device according to a second embodiment.

FIG. 4 is an explanatory side view showing a positional relationship between a degaussing coil and an external magnetic field shield structure according to a second embodiment.

FIG. 5 is a magnetization distribution diagram of a color selection electrode by a numerical analysis after a degauss operation using a degaussing coil (a) of a conventional example and a degaussing coil (b) of a second embodiment.

FIG. 6 is a magnetization distribution diagram of a color selection electrode by numerical analysis after a degauss operation by a degaussing coil according to a reference example.

FIG. 7A is a perspective view illustrating a configuration of a display device according to a third embodiment, and FIG. 7B is an enlarged cross-sectional view of a parallel portion of a degaussing coil.

8A is a side view illustrating the positional relationship between the degaussing coil of the reference example and the external magnetic field shield structure, and FIG. 8B is a rear view illustrating the arrangement of the degaussing coil.

FIG. 9 is a perspective view illustrating a configuration of a conventional display device.

FIG. 10 is an explanatory side view showing a positional relationship between a conventional degaussing coil and an external magnetic field shield structure.

FIG. 11 is a perspective view showing a shadow mask structure in an external magnetic field shield structure of a conventional CRT.

FIG. 12 is a perspective view showing a tension mask structure in an external magnetic field shield structure of a conventional CRT.

[Explanation of symbols]

H _ver Vertical magnetic field _Hew East-west magnetic field H _tube tube axial magnetic field 10 Display panel 11a Shadow mask structure 11b Tension mask structure 12 Internal magnetic shield 13 Electron gun 14 Funnel 15 Explosion-proof band 15 'Explosion-proof band with high permeability 16a First degaussing coil 16a -1 first parallel portion 16a-2 second parallel portion 16a-3 wraparound portion 16a-4 wraparound portion 16a-5 second parallel portion 16b second degaussing coil 16b-1 first parallel portion 16b-2 second parallel Part 16b-3 Surrounding part 16b-4 Surrounding part 16b-5 Second parallel part 17 Electron beam trajectory 18 External magnetic field shield structure 19 Neck 20 Color selection electrode 21 Frame 21a Angle 21b Arm 30 Magnetic flux

Continued on the front page (72) Inventor Hiroto Inoue 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hisanori Nagase 1006 Okadoma Kazuma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Person Kaneyoshi Takaura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kaku Uchida 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture F-term Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A cathode ray tube having a color selection electrode fixed to a frame under tension and an internal magnetic shield for magnetically shielding an electron beam, and a degaussing coil disposed in a funnel of the cathode ray tube The degaussing coil comprises a pair of upper and lower first and second degaussing coils, and the first and second degaussing coils are respectively arranged along an upper side or a lower side of the color selection electrode. A first parallel portion extending substantially parallel, a second parallel portion extending substantially parallel from both ends of the first parallel portion along a side of the color selection electrode, and the second parallel portion; A display device, comprising: a wrap-around portion that wraps around the side surface of the funnel from an end of the portion; and a portion where the wrap-around portions of the first and second degaussing coils are in contact with each other. 2. The display device according to claim 1, wherein the portions in contact with each other are provided near left and right side surfaces of the color selection electrode. 3. A first frame, wherein the frame supports the edge of the color selection electrode with tension applied thereto, and a second frame, which supports the first frame so as to apply tension to the color selection electrode. The display device according to claim 1, wherein the display device includes two frames. 4. The explosion-proof band provided has a relative magnetic permeability of not less than 2,000 and not more than 15,000, and the first and second degaussing coils are respectively provided with the first parallel portion or the second demagnetizing coil. The display device according to any one of claims 1 to 3, wherein the two parallel portions include a portion provided on the explosion-proof band. 5. The color selection electrode according to claim 1, wherein the color selection electrode is disposed in a region surrounded by the explosion-proof band.
The display device according to any one of the above. 6. The first degaussing coil and the second degaussing coil each have a flat cross section at a portion disposed on the explosion-proof band. The display device according to any one of the above.