JPH08273553A - Display device - Google Patents

Abstract

PURPOSE: To reduce the amount of mislanding of electron beams due to earth magnetism so as to restrain a color deflection error by forming a grid element from a multilayer structure including a high-permeability layer. CONSTITUTION: A CRT has a panel 1 on the inner surface of which a phosphor screen 2 is formed, and the panel 1 is welded to a funnel 3 with glass frit or the like. An electron beam 8 from an electron gun 7 attached to the neck of the funnel 3 scans the phosphor screen 2 of the panel 1. Inside the panel 1 is an aperture grille 11 serving as a grid main body. An electron-beam hole 10 comprising slits is formed through the grille 11. While tension is being applied in the direction of the slits of the electron-beam hole 10, the end piece of the grille 11 is welded to a frame 5. An inner magnetic shield 6 is joined to the back of the frame 5. The frame 5, the inner magnetic shield 6, and the aperture grille 11 constitute a magnetic shield structure. The grille 11 comprises a multilayer structure including a high permeability layer 12; i.e., the grille 11 has a base 14 of soft iron, layers 12 on surfaces at both sides of the base 14, and high electron reflectance layers 13 on the surfaces of the layers 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cathode ray tube (C
The present invention relates to a display device such as a television having an RT) or a CRT, and more particularly to a display device capable of reducing the mislanding amount of an electron beam due to the earth's magnetism and suppressing color misregistration.

[0002]

2. Description of the Related Art In a conventional CRT, an electron beam emitted from an electron gun passes through a slit (electron beam passage hole) of an aperture grill, hits a fluorescent substance at a landing point of the electron beam, and emits red (R), The desired color of green (G) and blue (B) is emitted.

However, between the electron gun and the fluorescent screen,
When the electron beam receives an external magnetic field such as geomagnetism, the electron beam receives a force due to the Lorentz force and its orbit changes, landing at a point displaced from the landing point when there is no external magnetic field, and when there is no external magnetic field. A part or all of the beam spot hits a phosphor different from that, causing a color shift.

In order to suppress this color shift, an internal magnetic shield is provided, and a magnetic shield is formed by this, a frame and an aperture grill to shield the external magnetic field and suppress the change in electron beam trajectory due to the external magnetic field. Is suppressed.

[0005]

However, the aperture grill has a small thickness of 0.1 mm or less, and has many slits through which the electron beam passes in the vertical direction of the panel surface. However, its effective non-hysteretic permeability is low, and the external magnetic field in the direction toward the panel surface of the CRT is not sufficiently shielded, and the color shift due to the external magnetic field in the direction toward the panel surface cannot be sufficiently suppressed. .

Particularly, in an aperture grill having electron beam passage holes formed in a slit shape, in order to prevent displacement of the slit due to thermal expansion during operation, the edge of the aperture grill is applied with tension applied to the aperture grill. To the frame. When tension is applied to the material forming the aperture grille, the non-hysteretic permeability of the material also decreases.
If the non-hysteretic permeability decreases, the effect of shielding the external magnetic field also decreases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a display device capable of reducing the mislanding amount of an electron beam due to geomagnetism and suppressing color misregistration.

[0008]

In order to achieve the above object, a display device according to the present invention comprises a panel having a phosphor screen on its inner surface and a grid element provided inside the panel and having an electron beam passage hole. A body, a frame that supports the grid element body, an internal magnetic shield attached to the frame, an electron gun that emits an electron beam toward the phosphor screen through the grid element body, the grid element body, A frame, an internal magnetic shield, and a funnel joined to the panel so as to cover the electron gun, the grid element body is a multilayer structure including a high magnetic permeability layer, the edge of the grid element body, It is characterized in that it is joined to the frame while tension is applied.

The electron beam passage hole formed in the grid element body has, for example, a slit shape, and the edge side of the grid element body extends along the longitudinal direction of the electron beam passage hole with respect to the frame. They are joined with tension applied. The grid element body is a substrate made of soft iron, a high magnetic permeability layer formed on at least one surface of the substrate, and a high electron reflectance layer formed on the outermost surface of the grid element body on the electron gun arrangement side. It is preferable to have and.

The high electron reflectivity layer can be formed by any one of thermal oxidation of the high magnetic permeability layer, vapor deposition of the high electron reflectivity layer, sputtering, and plating. When the maximum value of the AC magnetic field is 2 to 5 Oe and the DC magnetic field is 0.3 to 1 Oe, the non-hysteretic permeability of the grid element body is preferably 1000 or more in the state where tension is applied. From the viewpoint of improving the magnetic shield, the non-hysteretic permeability may be any value as long as it is 1000 or more, but in reality, it is 100.
It is about 0 to 10000.

The high-permeability layer can be made of any one of permalloy, iron-nickel alloy, amorphous magnetic material and high-purity iron. The high magnetic permeability layer is vapor-deposited,
It can be formed by either sputtering or plating.

[0012]

When the grid element body is an aperture grill or the like having slit-shaped electron beam passage holes, the grid element body has an average of 3 due to tension along the slit direction.
A tensile stress of 0 to 50 Kg / mm ² is applied. This is to prevent displacement of the electron beam passage hole due to thermal expansion during operation. However, the non-hysteretic magnetic permeability of the material is reduced to about 1/2 to 1/5 as compared with the case without tension. For this reason, the conventional grid element body has a sufficient non-hysteretic permeability in a state where no tension is applied,
After being attached to the frame in a state where tension is applied, the non-hysteretic magnetic permeability is reduced, and there is a possibility that a sufficient magnetic shield effect cannot be obtained.

In the display device according to the present invention, since the grid element body has a multi-layer structure including a high magnetic permeability layer, tension is applied to the edges of the grid element body with respect to the frame. Even if the grid elements are joined together in the above state, the non-hysteretic magnetic permeability of the grid element body is maintained in a high state of 1000 or more. Therefore, the grid element exerts a sufficient magnetic shield effect, suppresses fluctuation of the trajectory of the electron beam due to geomagnetism, and prevents deviation of the landing point of the electron beam.
For this reason, color misregistration can be prevented.

The non-hysteretic magnetic permeability of the grid element is 1000
It has been confirmed by the inventor of the present invention that in the above cases, the mislanding amount of the electron beam (deviation amount from the normal landing point) can be significantly suppressed. In the present invention, the non-hysteretic permeability (μ _u ) means that the maximum value of the AC magnetic field is 2 to 5 Oe and the DC magnetic field is 0.3 to 1 Oe, as shown in FIGS. 4 (a) and 4 (b). In the case of, it can be expressed as B _ru / H _dc . Here, B _ru is the residual magnetic flux density (Gauss) after the non-history process, and H _dc is the DC magnetic field (Oe) applied to the magnetic body.

In FIG. 4A, the horizontal axis corresponds to the elapsed time and the vertical axis corresponds to the magnetic field strength (Oe). Figure 4 (a)
The middle graph shows an AC attenuation magnetic field due to the DC magnetic field applied to the magnetic material, and finally settles down to the DC magnetic field H _dc due to the earth magnetism. In FIG. 4B, the horizontal axis represents the magnetic field strength and the vertical axis represents the magnetic velocity density. The graph in FIG.
The non-hysteresis remanent magnetization process when the magnetic field shown in (a) is applied to a magnetic body is shown, and the magnetic velocity density settles to the residual magnetic velocity density B _ru by geomagnetism.

In the present invention, the high electron reflectivity layer is formed on the outermost surface of the grid element body on the side where the electron gun is disposed, so that the electron beam irradiating to the area other than the electron beam passage holes of the grid element body is reflected and the grid element body. Can be effectively prevented from being heated. The high electron reflectivity layer can be easily formed by a method such as thermal oxidation of the high magnetic permeability layer, vapor deposition of the high electron reflectivity layer, sputtering or plating. In particular, when the high magnetic permeability layer is one of permalloy, iron-nickel alloy, amorphous magnetic material, and high-purity iron, the high electron reflectance layer can be easily formed by thermal oxidation. In the present invention, high purity iron means that the purity of iron is 99.
It is 8% or more, preferably 99.99% or more, and it is desirable that the non-hysteretic magnetic permeability is high.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The display device according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 is a schematic sectional view of a CRT as a display device according to an embodiment of the present invention, FIG.
4 is a front view of an aperture grille as a grid element, FIG. 3 is a cross-sectional view of a main part of the aperture grille shown in FIG. 2, and FIG.
4A is a graph showing an AC decay magnetic field in which a DC magnetic field applied to a magnetic material is superimposed, FIG. 4B is a graph showing a non-hysteretic residual magnetization process, and FIG. 5 is a graph showing non-hysteretic permeability and mislanding amount of an aperture grill. FIG. 6 is a graph showing the relationship between the effective non-hysteretic permeability and the magnetic field attenuation rate.
FIG. 7 is a schematic diagram of a model for testing magnetic shield performance.

As shown in FIG. 1, the CRT has a panel 1 having a phosphor screen 2 formed on the inner surface thereof. The panel 1 is fused with the funnel 3 by frit glass or the like. The interior of the space surrounded by the panel 1 and the funnel 3 is maintained at a high degree of vacuum so that the electron beam 8 from the electron gun 7 mounted on the neck of the funnel 3 scans toward the fluorescent screen 2 of the panel 1. It has become. An aperture grille 11 serving as a grid element body is arranged inside the panel 1 so as to face the phosphor screen 2 of the panel 1.

As shown in FIG. 2, the aperture grill 11 has a slit-shaped electron beam passage hole 10 formed therein. The edge side of the aperture grill 11 is welded and fixed to the frame 5 in a state where tension is applied to the aperture grill 11 in the slit direction of the electron beam passage hole 10. The tension is not particularly limited, but is, for example, 30 on average.
Aperture grille 1 with a tensile stress of ~ 50Kg / mm ²
It only acts on 1. The reason why the tension is applied in this way is to prevent the position of the electron beam passage hole from being displaced due to thermal expansion during operation.

As shown in FIG. 1, behind the frame 5 (on the side of the electron gun), the passage of the electron beam 8 is not obstructed, and the influence of external magnetism such as geomagnetism from the outer circumference is shielded. The internal magnetic shield 6 is joined. The electron beam 8 emitted from the electron gun 7 passes through the electron beam passage hole 10 of the aperture grill 11 and hits the center of the desired phosphor on the phosphor screen 2 at the landing point 9 to emit a predetermined color. . However, when the electron beam 8 receives an external magnetic field such as terrestrial magnetism from the electron gun 7 to the phosphor screen 2, it receives a force due to the Lorentz force and its orbit changes. As a result, landing is performed at a point deviated 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 a color shift. In order to prevent this, in the CRT, as shown in FIG. 1, a magnetic shield structure is formed by the frame 5, the internal magnetic shield 6, and the aperture grill.

In the conventional CRT, the influence of the external magnetic field from the outer peripheral direction was satisfactorily shielded by the internal magnetic shield, but the aperture grilles have become thinner with the miniaturization of pixels, and the external magnetic field in the tube axis direction has become smaller. However, there is a problem in that the effect of can not be shielded well. In addition, the aperture grill 11 is
The tension exerts an average tensile stress of 30 to 50 kg / mm ² . Therefore, the non-hysteretic permeability of the material forming the aperture grill is 1 compared to the case without tension.
/ 2 to about 1/5. Therefore, the conventional grid element has a sufficient non-hysteretic permeability in a state where no tension is applied, but the non-hysteretic permeability decreases after being attached to the frame in a state where tension is applied. However, there is a possibility that a sufficient magnetic shield effect cannot be obtained.

In this embodiment, as shown in FIG. 3, the above-mentioned problem is solved by forming the aperture grill 11 with a multi-layer structure including the high magnetic permeability layers 12 and 12. That is, in this embodiment, the aperture grille 11 is formed of the substrate 14 made of soft iron, the high magnetic permeability layers 12 formed on both side surfaces of the substrate 14, and the surface of the high magnetic permeability layer 12. And a high electron reflectance layer 13.

The thickness of the substrate 14 made of soft iron is not particularly limited, but is about 100 to 25 μm. It is preferable that the substrate 14 is thin from the viewpoint of increasing the screen density and reducing the tension applied to the aperture grill. However, from the viewpoint of enhancing the magnetic shielding effect, the thickness is preferably thick.

High permeability layer 1 formed on both sides of the substrate 14.
2 is, for example, permalloy, iron-nickel alloy, amorphous magnetic material, high-purity iron (iron purity of 99.8% or more,
It is preferably 99.99% or more). The thickness of the high magnetic permeability layer 12 is not particularly limited, but is, for example, 5
It is about 30 μm. The high magnetic permeability layer 12 is formed on both surfaces of the substrate 14 by a method such as vapor deposition, sputtering and plating. The non-hysteretic magnetic permeability of the high magnetic permeability layer 12 is 2000 or more in the state where no tension is applied. For example, the non-hysteretic magnetic permeability of permalloy is 8000 to 10000.
By applying tension, the non-hysteretic permeability of the high-permeability layer 12 is reduced to about 1/2 to 1/5, but since the original non-hysteretic permeability is high, even when tension is applied,
It will be over 1000.

The non-hysteretic permeability is shown in FIG.
As shown in (b), the maximum value of the AC magnetic field is 2 to 5 Oe.
Then, when the DC magnetic field is 0.3 to 1 Oe, it can be expressed as B _ru / H _dc . Here, B _ru is the residual magnetic flux density (Gauss) after the non-history process, and H _dc is the DC magnetic field (Oe) applied to the magnetic body.

In the present embodiment, the overall non-hysteretic magnetic permeability of the aperture grille 11 including the high magnetic permeability layer 12 is maintained at 1000 or more even when tension is applied. FIG. 5 shows the relationship between the non-hysteretic permeability of the aperture grille and the amount of mislanding at the upper right corner of the CRT. In the simulation shown in FIG. 5, a magnetic field of 0.35 Oe, which is almost the same as the earth's magnetism, is applied in the axial direction of the CRT, and the relationship between the non-hysteretic permeability of the aperture grill and the amount of mislanding at the upper right corner of the CRT is shown. I asked. In this simulation, the total thickness of the aperture grill was set to 0.1 μm, the non-hysteretic permeability of the frame 5 shown in FIG. 1 was set to 500, and that of the inner magnetic shield 6 was set to 7000, and the calculation was performed. Here, the mislanding amount indicates the amount of deviation of the electron beam from the actual landing point with respect to the desired landing point 9 shown in FIG.

As shown in FIG. 5, the non-hysteretic magnetic permeability is 10
At 0 or less, the mislanding amount is 30 μm or more, but begins to decrease when the non-hysteretic permeability of the aperture grill becomes 100 or more, and decreases to 20 μm when the non-hysteretic permeability of the aperture grill becomes 1000.

The permissible value of the amount of mislanding due to the geomagnetism of a CRT having a phosphor pitch of 0.25 to 0.3 mm is about 20 μm or less, so that if the hysteresis hysteresis magnetic permeability of the aperture grill becomes 1000 or more, This allowable value can be satisfied and color misregistration can be suppressed.

FIG. 6 shows the result of calculation of the magnetic shield performance of the aperture grill of the multi-layer structure shown in FIG. 3 using the model of an infinite cylinder shown in FIG. In FIG. 7, the double cylindrical high magnetic permeability layer 16 corresponds to the high magnetic permeability layer 12 shown in FIG. 3, and the intermediate layer 15 shown in FIG. 7 corresponds to the soft iron substrate 14 shown in FIG. In the calculation of FIG. 6, the intermediate layer 15 is calculated as an air layer in order to see the effect of the multilayer structure. From the results shown in FIG. 6, when the thickness of the high magnetic permeability layer is 10 μm,
When the non-hysteretic permeability is about 4800 or more and the thickness of the high-permeability layer is 20 μm, the non-hysteretic permeability is about 2
It has been confirmed that if it is 500 or more, a soft iron single layer having a thickness of 0.1 μm has a shielding effect with an anti-hysteretic permeability of 1000 or more. In FIG. 7, the intermediate layer 15 is calculated as an air layer, but as shown in FIG. 3, since the soft iron substrate 14 is arranged between the high magnetic permeability layers 12 and 12, the non-magnetic layer 15 as a whole is The hysteresis magnetic permeability can be 1000 or more even when tension is applied to the aperture grill 11.

The non-hysteretic permeability of the aperture grill 11 is set to 1
If it can be 000 or more, as shown in FIG.
The mislanding amount can be significantly reduced to 20 μm or less, and color misregistration can be suppressed. In the present embodiment, as shown in FIG. 3, the surface of the high magnetic permeability layer 12 is
A high electron reflectance layer 13 is formed. High electron reflectance layer 1
3 is formed, for example, by thermally oxidizing the surface of the high magnetic permeability layer 12, and the thickness thereof is not particularly limited, but is, for example, about 5 to 20 nm. High electron reflectance layer 13
Is most easily formed by thermal oxidation at about 450 ° C., but it can also be formed by a method such as vapor deposition, sputtering or plating.

The high electron reflectance layer 13 is formed by CR
During the operation of T, the electron beam passage hole 10 shown in FIG.
This is because the heating of the aperture grill 11 is suppressed by reflecting the electron beam applied to the surface of the aperture grill 11 other than the above. The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways within the scope of the present invention.

For example, the high magnetic permeability layer 12 shown in FIG.
It may be formed on only one side of the substrate 14 without being formed on both sides thereof, or may be located inside the substrate. Further, the high electron reflectance layer 13 may be formed on at least the surface of the aperture grill 11 on the side of the electron gun without forming on both sides of the aperture grill 11.

Further, as the grid element used in the display device of the present invention, not only the aperture grill having the slit-shaped electron beam passage hole but also the electron beam passage hole of other shapes may be formed. Furthermore, although only the CRT has been described in the above-described embodiment, the present invention is not limited to the CRT and can be applied to other display devices (including a television).

[0034]

As described above, according to the present invention, the grid element body has a multi-layered structure including a high magnetic permeability layer, so that the grid element body can be applied even when tension is applied to the grid element body. It becomes easy to maintain the non-hysteretic magnetic permeability of the body at 1000 or more. Therefore, the magnetic shield effect of the grid element is improved, the mislanding amount of the electron beam due to the geomagnetism from the tube axis direction is reduced, and the color shift can be suppressed.

Further, since the grid element body is not composed only of an expensive material composed of permalloy having a high magnetic permeability, the manufacturing cost is not significantly increased. further,
Since the substrate composed of soft iron or the like is responsible for the tensile strength resistance and the easiness of etching (for forming the electron beam passage holes) required for the grid element body, the performance as the grid element body is not deteriorated.

When the number of high magnetic permeability layers is two or more, the non-hysteretic magnetic permeability is further improved and the magnetic shield effect is enhanced. Therefore, the grid element body can be easily thinned.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a CRT as a display device according to an embodiment of the present invention.

FIG. 2 is a front view of an aperture grille as a grid element body.

FIG. 3 is a sectional view of a main part of the aperture grille shown in FIG.

FIG. 4A is a graph showing an AC damping magnetic field in which a DC magnetic field applied to a magnetic material is superimposed, and FIG. 4B is a graph showing a non-hysteretic residual magnetization process.

FIG. 5 is a graph showing the relationship between the non-hysteretic permeability of the aperture grill and the amount of mislanding.

FIG. 6 is a graph showing the relationship between effective non-hysteretic permeability and magnetic field attenuation rate.

FIG. 7 is a schematic diagram of a model for testing magnetic shielding performance.

[Explanation of symbols]

 1 ... Panel 2 ... Fluorescent screen 3 ... Funnel 5 ... Frame 6 ... Internal magnetic shield 7 ... Electron gun 8 ... Electron beam 9 ... Landing point 10 ... Electron beam passage hole 11 ... Aperture grill 12 ... High permeability layer 13 ... High electron Reflectivity layer 14 ... Substrate

Claims (7)

[Claims] 1. A panel having a phosphor screen on an inner surface thereof, a grid element body provided inside the panel and having electron beam passage holes, a frame for supporting the grid element body, and an interior attached to the frame. A magnetic shield, an electron gun that emits an electron beam toward the phosphor screen through the grid element body, and a funnel bonded to the panel so as to cover the grid element body, the frame, the internal magnetic shield, and the electron gun. And wherein the grid element body is a multi-layer structure including a high magnetic permeability layer, and an edge of the grid element body is joined to the frame in a state in which tension is applied. And display device. 2. An electron beam passage hole formed in the grid element body is slit-shaped, and an end side of the grid element body extends along a longitudinal direction of the electron beam passage hole with respect to the frame. The display device according to claim 1, wherein the display device and the display device are bonded to each other while being applied with a tension. 3. The grid element body is formed on a substrate made of soft iron, a high magnetic permeability layer formed on at least one surface of the substrate, and an outermost surface of the grid element body on the electron gun arrangement side. A high electron reflectivity layer and a high electron reflectivity layer.
The display device according to claim 1. 4. The display device according to claim 3, wherein the high electron reflectance layer is formed by any one of thermal oxidation of the high magnetic permeability layer, vapor deposition, sputtering, and plating of the high electron reflectance layer. . 5. When the maximum value of the AC magnetic field is 2 to 5 Oe and the DC magnetic field is 0.3 to 1 Oe, the non-hysteretic permeability of the grid element is 1000 or more in a state where tension is applied. It exists, The display apparatus in any one of Claims 1-4. 6. The display device according to claim 1, wherein the high magnetic permeability layer is one of permalloy, iron-nickel alloy, amorphous magnetic material, and high-purity iron. 7. The display device according to claim 1, wherein the high magnetic permeability layer is formed by any one of vapor deposition, sputtering and plating.