KR100418933B1 - Inner shield for color CRT - Google Patents

Abstract

The present invention relates to an inner shield for a color cathode ray tube, and to improve the quality of geomagnetic margin by minimizing mis-landing of the electron beam by allowing the magnetic field flow in the inner shield to be linear.

To this end, the present invention, in the inner shield that serves to shield the inside of the cathode ray tube from an external magnetic field, the inner shield is composed of a material having a permeability different from the long side and the short side, preferably the inner shield The long side portion is made of low carbon steel, which is a low permeability material, and the short side portion is made of directional silicon steel having a high permeability, to provide an inner shield for color cathode ray tubes.

Description

Inner shield for color cathode ray tube {Inner shield for color CRT}

The present invention relates to an inner shield of a color cathode ray tube, and more particularly, to an inner shield for a color cathode ray tube that can improve the quality of geomagnetic margin by minimizing mis-landing of an electron beam by allowing the magnetic field flow to be linear in the inner shield. It is about.

In general, the cathode ray tube is used as an image tube of a video display device such as a television or a monitor, and is classified into a convexed type and a plane type according to the shape of the image surface. Due to the phenomenon, the demand is gradually decreasing, whereas the flat type is closer to the screen, and the demand is gradually spreading.

In addition, as the structure of cathode ray tube is gradually flattened and refined, a series of studies are performed to improve the purity of the screen, to prevent reflection of the outside surface of the panel by external light, and to minimize the reflection of light generated when the phosphor formed on the inside of the panel emits light. Is actively underway.

1 of the accompanying drawings shows a structure of such a general flat cathode ray tube, the flat CRT is a panel (1) attached to the explosion-proof glass (2) having explosion-proof characteristics on the front surface and the panel (1) A funnel 4 fused by frit glass, an electron gun 7 encapsulated in the neck 5 of the funnel 4 to radiate red, green, and blue electron beams 6 toward the panel 1, On the inner surface of the panel 1, a screen 1a formed by applying a fluorescent film that emits light by an electron beam 6 and a myriad of holes are formed so that the electron beam strikes a predetermined fluorescent film of the screen 1a to emit light. It comprises a shadow mask (3) for the color screening function, and a rail (9) for supporting the shadow mask (3) by applying a tensile force to maintain a constant distance from the inner surface of the panel, the rail (9) has a cathode ray tube Even if it is less affected by external geomagnetic The inner shield 10 serving as the shield shield is welded and fixed.

The rail 9 is fused and bonded to the inner surface of the panel 1 by frit glass to withstand the tensile force of the shadow mask 3. As described above, applying the tensile force to the shadow mask 3 implies that the electron beam is applied to the shadow mask. This is to prevent such deformation because heat energy is generated when it hits, causing deformation in the shadow mask.

However, the inner shield 10 for the cathode ray tube having the same shape as that shown in FIG. 2 has a long side portion 10a and a short side portion 10b of the same material, and thus affects the progress of the electron beam. There was a problem causing landing.

This will be described in more detail as follows.

FIG. 3 shows a magnetic field flow formed in the screen 1a of the cathode ray tube by the conventional inner shield 10, and the horizontal magnetic field Bh generated in the inner shield 10 is in a horizontal direction at a distance from the inner shield. The path of the magnetic field is changed at a close distance, and the magnetic path on the outer surface of the inner shield 10 has little effect on the path of the electron beam in the path of the magnetic field. 10) The magnetic field path in the inner surface greatly affects the path of the electron beam.

That is, since the flow of the magnetic field in the horizontal direction in the magnetic path in the inner surface of the inner shield 10 causes the vertical movement of the electron beam does not change the purity, the magnetic field flow in the vertical direction causes the left and right movement of the electron beam As shown in FIG. 3, in the magnetic field flow in the inner surface of the inner shield 10 of the related art, the magnetic field flow in the center, top, bottom, left and right sides of the screen is horizontal, but the magnetic field flow in the corner portion of the screen is It shows the magnetic field flow including horizontal and vertical direction.

Therefore, in the magnetic field flow at the screen corner, the horizontal component MFx moves the electron beam up and down and thus does not cause mis-landing, but the vertical component MFy moves the electron beam to the left and right to cause mis-landing. do.

For example, in the reference field (Bv = 0.4G, Bh = 0.0G, Bz = 0.0G), the trend field (Bv = 0.4G, Bh = 0.3G, Bz = 0.0G) or the westward magnetic field (Bv = 0.4G, If Bh = -0.3G, Bz = 0.0G), mis-landing occurs at the corner of the screen, which reduces the quality of geomagnetic margin.

To this end, in order to compensate for the geomagnetic margin in the east-west direction in which the quality of the geomagnetic margin is reduced as described above, a purity coil or a local current controller (LCC) circuit is applied to the monitor circuit, but in this case, the monitor circuit is not only complicated. There is a problem that raw material costs rise.

Accordingly, the present invention has been made to solve the above problems, by improving the magnetic field flow generated in the inner shield to be horizontal in all parts to prevent the mis-landing caused by the vertical component of the magnetic field flow The purpose is to provide an inner shield for color cathode ray tubes.

1 is a sectional view showing the main parts of a structure of a general flat color cathode ray tube;

2 is a front view of an inner shield for a conventional cathode ray tube

3 is a view illustrating a magnetic field flow formed on a screen by a magnetic field flow of a conventional inner shield;

4 is a perspective view showing an inner shield according to the present invention;

5 is a front view of the inner shield of FIG.

6 is a view showing a magnetic field flow formed on the screen by the magnetic field flow of the inner shield of the present invention.

* Explanation of symbols for the main parts of the drawings *

1a: screen 6: electron beam

100: inner shield 101: long side

102: short side

In order to achieve the above object, the present invention, in the inner shield that serves to shield the inside of the cathode ray tube from the external magnetic field, the inner shield is composed of a material having a long permeable portion and a short side portion having different permeability, Preferably, the inner shield long side portion is a low-carbon magnetic material having a low permeability material, and the short side portion provides an inner shield for color cathode ray tube, characterized in that the high permeability directional silicon steel.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the inner shield for the color cathode ray tube according to the present invention.

4 is a perspective view showing an inner shield for a cathode ray tube according to the present invention, Figure 5 is a rear view of the inner shield seen from the electron gun side of the cathode ray tube, as shown in Figures 4 and 5, the inner shield 100 is approximately the front It is in the form of a square pyramid and the back is open, the long side portion 101 and the short side portion 102 is made of different materials, the long side portion 101 is made of low carbon steel, a low permeability material of less than 10000G / Oe The short side portion 102 is made of oriented silicon steel, which is a high permeability material of 10000 G / Oe or more.

Preferably, the maximum permeability of the long side portion 101 of the inner shield 100 is 5429.6 (G / Oe), and the maximum permeability of the short side portion 102 is 18896.5 (G / Oe) of the long side portion 101. It is about 3.5 times higher than the maximum permeability.

Table 1 below shows the physical properties of each material of the inner shield 100 of the present invention configured as described above.

location material Hc (Oe) Bs (G) Br (G) μi (G / Oe) μmax (G / Oe) Long side Low carbon steel 1.3 16163.3 10900.5 2629.9 5429.6 Short edge Oriented silicon steel 0.13 21099.2 1881.2 14397.3 18896.5

In Table 1, Hc represents coercive force, Bs represents saturation magnetization, Br represents residual magnetization, μi represents initial permeability, and μmax represents maximum permeability.

In general, compared to low carbon steels, directional silicon steels have a high permeability due to their magnetization biaxiality being parallel to the magnetic field and decreasing crystal anisotropy.

The inner shield 100 configured as described above acts as follows.

6 illustrates a magnetic field flow formed in the screen 1a when the inner shield 100 according to the present invention is applied. According to the present invention, the long side portion 101 of the inner shield 100 is formed of a material having a low permeability. By using the high permeability material of the short side portion 102, the flow of the horizontal magnetic field generated in the inner shield 100 can be changed from the conventional elliptical flow to the linear flow, thereby allowing the center of the screen 1a to be changed. The magnetic field flow at each corner of the screen 1a as well as up and down and left and right also show a horizontal magnetic field flow without vertical components, so that the electron beam is only caused to move up and down.

Table 2 below shows the results obtained by experiments on the purity change of each material combination when the long side portion 101 and the short side portion 102 of the inner shield 100 are used in combination with low carbon steel and directional silicon steel. .

material Purity change Long side Short edge Winter North and South Low carbon steel Low carbon steel 17.0 12.2 Oriented silicon steel Low carbon steel 24.2 10.6 Low carbon steel Oriented silicon steel 7.6 10.0 Oriented silicon steel Oriented silicon steel 12.2 8.6

As shown in Table 2, when the long side portion 101 of the inner shield 100 is made of low carbon steel and the short side portion 102 is made of directional silicon steel, the Purity characteristics in the east-west direction are the best.

As described above, according to the present invention, the magnetic field flow inside the inner shield becomes linear by using a material having a low permeability and a long permeable portion of the inner shield of the cathode ray tube and a material having a high permeability. It is possible to minimize mis-landing of the electron beam at the corners of the screen, thereby improving the quality of geomagnetic margin.

Claims (4)

In the inner shield that serves to shield the inside of the cathode ray tube from an external magnetic field, The inner shield is an inner shield for a color cathode ray tube, characterized in that the long side portion and the short side portion is composed of a material having a different permeability. The inner shield of claim 1, wherein the long side portion of the inner shield is made of a material having a low permeability, and the short side portion of the inner shield is made of a material having a high permeability. The inner shield for a color cathode ray tube according to claim 2, wherein the long side portion of the inner shield is made of a material of low carbon steel, and the short side portion is made of a material of directional silicon steel. The inner shield for color cathode ray tube according to claim 2 or 3, wherein the long side portion of the inner shield has a maximum permeability of less than 10000 G / Oe, and the short side portion has a maximum permeability of 10000 G / Oe or more.