KR100658708B1 - Inner shield for cathode ray tube - Google Patents

Abstract

The present invention relates to an inner shield for a cathode ray tube that can minimize the amount of change in landing of an electron beam by a geomagnetic field by changing the distribution of the geomagnetic field around the inner shield

A flange portion fixed to the mask frame, a pair of long side body portions and a short side body portion having a predetermined inclination such that the gap between the flange portion toward the electron gun is gradually narrowed, and an upper surface opening facing the electron gun; At least one side of the upper opening may include a high permeability portion having a higher permeability than the long side and short side body parts to provide an inner shield for a cathode ray tube for changing the distribution of the geomagnetic field in a direction to reduce the force applied to the electron beam.

The high investment portion reduces the horizontal movement of the electron beam by the NS geomagnetic field when provided at two long sides of the top opening, and effectively reduces the horizontal movement of the electron beam by the EW geomagnetic field when provided at the two short sides of the top opening. Decrease.

Cathode ray tube, inner shield, mask frame, electron gun, high investment part, electron beam movement amount, ns magnetic field, double retainer field

Description

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

1 is a side cross-sectional view of a cathode ray tube equipped with an inner shield according to the present invention.

2 is a schematic view for explaining the basic axis of the cathode ray tube.

3 is a perspective view of the inner shield according to the first embodiment of the present invention.

4 is a graph showing the change of the geomagnetic field distribution in the prior art and the present invention.

5 is a perspective view of an inner shield according to a second embodiment of the present invention;

6 is a graph showing the change of the geomagnetic field distribution in the prior art and the present invention.

7 is a perspective view of an inner shield according to a third embodiment of the present invention.

8A and 8B are schematic diagrams for explaining the N-S movement amount and the E-W movement amount.

9 is a perspective view of an inner shield according to the prior art;

The present invention relates to an inner shield of a cathode ray tube, and more particularly, to an inner shield for a cathode ray tube capable of minimizing a change in landing of an electron beam by a geomagnetic field by changing a distribution of a geomagnetic field around an inner shield.

In general, a cathode ray tube is a display device that implements a predetermined screen by scanning a fluorescent screen with three stem electron beams emitted from an electron gun. In this case, the electron beam path is subjected to a geomagnetic field generated by the earth's north and south poles. Changes are influenced by purity characteristics, raster position, and convergence characteristics.

These geomagnetic fields are divided into vertical components perpendicular to the ground (vertical geomagnetic field) and horizontal components parallel to the ground (horizontal geomagnetic field), and represent different values depending on the place on the earth. The electron beam movement can be explained by dividing the NS movement amount and the EW movement amount according to the direction in which the cathode ray tube is directed.

That is, as shown in FIGS. 8A and 8B, the NS movement amount refers to the electron beam movement amount by a component that matches the tube axis zz of the cathode ray tube among the horizontal geomagnetic fields, and the EW movement amount corresponds to the tube axis of the cathode ray tube among the horizontal geomagnetic fields. Means the amount of electron beam movement by the vertical component.

On the other hand, the landing change amount of the electron beam appearing on the screen under the influence of the geomagnetic field can be analyzed by dividing it into a horizontal component and a vertical component.

At this time, in both the shadow mask which is mainly applied to the commercial cathode ray tube and has a long slot in the vertical direction, and the shadow mask which is mainly applied to the industrial cathode ray tube and has a dot-shaped hole, the horizontal moving component of the electron beam is defined as the electron beam. Because of the distance away from the slot or hole, suppressing this horizontal shift component is an important task.

Therefore, the inner shield is mounted inside the cathode ray tube for the purpose of reducing the amount of change in the landing of the electron beam caused by the geomagnetic field. FIG. 9 is a perspective view of the inner shield according to the prior art, and the inner shield 1 mainly has a high permeability and a low permeability. It is made of metal of coercive material and is fixedly installed behind the mask frame 3 so as to surround the electron beam path.

As a result, the inner shield 1 becomes a kind of magnetic material during driving of the cathode ray tube, and serves to change the distribution of the surrounding magnetic field in a direction to reduce the amount of change in landing of the electron beam while canceling or constructive interference with the geomagnetic field around the electron beam.

Regarding the function of the inner shield, Korean Utility Model Publication No. 98-18551 "Inner Shield of Cathode Ray Tube" and Korean Patent Publication No. 99-5544 "Inner Shield of Color Cathode Ray Tube" are changed in shape of inner shield. Through this, the contents to reduce the influence of the geomagnetic field on the electron beam are disclosed.

However, most inner shields including the above structure have a tendency to increase the influence of the EW geomagnetic field in one direction, for example, the NS geomagnetic field. There were limitations that were difficult to implement.

Therefore, the present invention has been devised to solve the above problems, and an object of the present invention is to effectively reduce the NS movement amount without increasing the EW movement amount, and to improve the screen quality by reducing the horizontal moving component of the electron beam which greatly affects the screen characteristics. To provide an inner shield for the cathode ray tube that can be made.

In order to achieve the above object, the present invention,

A flange portion fixed to the mask frame, a pair of long side body portions and a short side body portion having a predetermined inclination such that the gap between the flange portion toward the electron gun is gradually narrowed, and an upper surface opening facing the electron gun; ,

At least one side of the upper opening is formed of a high permeability portion having a higher permeability than the long side and short side body portion to provide an inner shield for the cathode ray tube for changing the distribution of the geomagnetic field in a direction to reduce the force applied to the electron beam.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a side cross-sectional view of a cathode ray tube equipped with an inner shield according to the present embodiment, and FIG. 2 is a schematic view for explaining a basic axis of the cathode ray tube.

As shown in the drawing, the cathode ray tube combines the face panel 2, the funnel 4, and the neck portion 6 integrally to form a vacuum bulb 8, and a plurality of R, G on the inner surface of the face panel 2. And a fluorescent screen 10 having a B fluorescent film is formed, and the deflection yoke 12 and the electron gun 14 are integrally mounted to the outer circumferential surface of the funnel 4 and the inner circumferential surface of the neck portion 6, respectively. .

A shadow mask 16 having a plurality of beam passing apertures 16a formed therein is fixed to the mask frame 18 and installed inside the cathode ray tube so as to face the fluorescent screen 10, and one end of the inner shield 20. It is fixed to the mask frame 18 and mounted to surround the electron beam path.                     

According to the above-described configuration, when the electron gun 14 emits a three-stage electron beam corresponding to the screen signal, the electron beam is deflected by the magnetic field in which the deflection yoke 12 is generated to form a raster on the screen. By the R, G, B fluorescent film is separated by the correct color and the screen is implemented.

As such, the electron beam must move along the designated path, forming a raster specified by the deflection magnetic field, and the three-stripe electron beam matches exactly at one beam passing aperture 16a (i.e., achieves good convergence characteristics). Accurate screen can be realized.

As a result, the inner shield 20 surrounding the electron beam path serves to shield the geomagnetic field that affects the electron beam movement to a certain level. In particular, in the present embodiment, the amount of horizontal movement of the electron beam having a large influence on the screen characteristics such as other color invasion It provides a new configuration of the inner shield that can effectively reduce the

3 is a perspective view of the inner shield according to the present embodiment, wherein the inner shield 20 is connected to each other toward a flange portion 22 fixed to the mask frame 18 and an electron gun not shown in the flange portion 22. It consists of a pair of long side body part 24 and short side body part 26 which have predetermined inclination so that a space may become narrow gradually, and two long sides of the upper side opening part 28 which faces an electron gun are comprised of the high investment part 30. .

The high permeability part 30 provided on the two long sides of the top opening 28 is made of a material having a higher permeability than the long sides and the short side body parts 24 and 26 of the inner shield 20, and is formed by the geomagnetic field in the NS direction. It serves to reduce the amount of horizontal movement of the electron beam by changing the distribution of the geomagnetic field around the inner shield in the direction of reducing the horizontal force received by the electron beam.

That is, the horizontal force Fx applied to the electron beam by the external geomagnetic field may be expressed by Equation 1 below.

Fx = -e (VyBz-VzBy)

Here, e (C) is the charge amount, Vy and Vz (m / s) are the y- and z-direction velocities of the electron beam, and By and Bz (T) are the magnitudes of the y- and z-direction geomagnetic field components, respectively.

As described above, the force in the horizontal direction defined by Equation 1 is determined by the magnitude of the geomagnetic field formed around the electron beam, that is, By and Bz values, in a state where the speed of the electron beam is constant.

Therefore, the present embodiment reduces the absolute value of Fx by changing the distribution of the geomagnetic field around the inner shield 20, that is, By and Bz, using the high investment unit 30. Is a graph showing the distribution change of the NS geomagnetic field with respect to the electron beam landing on the screen diagonal portion in the inner shield and the inner shield according to the present embodiment.

Here, the inner shield according to the prior art is a configuration in which the high investment portion 30 is not formed in the top opening 28 in the same shape as the inner shield according to the present embodiment, and the body and the body of the prior art and the present embodiment have the same material. It was used to produce.

As a result, the By 'and Bz' distribution when the inner shield is mounted according to the prior art and the By and Bz distribution when the inner shield is mounted according to the present embodiment are measured and illustrated in the graph, and the horizontal axis of the graph is an electron gun 14. ) Means the distance from the tube axis, i.e., the z-axis, to the fluorescent screen 10, and the vertical axis represents the intensity of the magnetic field.

In particular, the reference line (R / L) on the horizontal axis represents a point on the tube axis at which the angle formed between the straight line and the tube axis is the maximum deflection angle when the straight line is drawn on the tube axis in the diagonal axis of the face panel. Denotes the starting point of deflection of the electron beam.

In addition, the 0.0 point on the horizontal axis means the starting point of the inner shield where the upper opening 28 of the inner shield 20 is located, and the intensity of the magnetic field having a negative value indicates that the arrow tip of the three axes shown in FIG. This means that the magnetic field is distributed in the opposite direction to the plus direction.

Therefore, when looking at the geomagnetic field distribution shown in the graph, By represents a value that is generally increased from the conventional By 'over the entire section from R / L to the fluorescent screen in the structure according to the present embodiment.

In the structure according to the present embodiment, Bz shows a decreased value from the conventional Bz 'toward the fluorescent film screen at R / L, and then increases to a specific point and increases from the conventional Bz'. As a result, when comparing the sum of them over the entire measurement interval, the Bz according to the present example shows a value similar to or less than that of the conventional Bz '.

Accordingly, when Bz decreases and By increases over the cathode ray tube tube axis, Bz decreases, and the difference between these Bz and By decreases, and the absolute value of Fx defined in Equation 1 decreases. This can reduce the absolute value of Fx even when Bz increases than the existing Bz ', if By increases more than Bz.

Here, the By represents an increased value of the conventional By ', so that the pair of high-permeability parts 30 focus the By acting in the vertical direction around the inner shield 20 so that the negative component thereof is positive. Because it leads to the direction.

Therefore, this embodiment effectively reduces the horizontal movement of the electron beam by the NS geomagnetic field by reducing the difference between Bz and By. Table 1 below shows the angles of the geomagnetic field measurement intervals in the present embodiment and the prior art. The sum of the strengths of the magnetic fields and the magnitude of Fx are compared.

Bz sum (G) By sum (G) Bz-By (G) Fx (N) Example 43 0.319 42.68 3.13 × 10 ^-14 Comparative example 42.9 -1.38 44.28 3.31 × 10 ^-14

In this case, Fx is calculated by substituting Vy and Vz mentioned in Equation 1 at 0.460 × 10 ⁸ m / s and 0.675 × 10 ⁸ m / s, respectively.

As described above, it can be seen that the present embodiment in which the high investment portion 30 is formed on two long sides of the upper opening 28 as compared with the conventional technology effectively reduces the horizontal force applied to the electron beam by the N-S geomagnetic field.

Figure 5 is a perspective view of the inner shield according to another embodiment of the present invention, in the present embodiment instead of forming a high investment portion in the two long sides of the top opening in the configuration of the previous embodiment, the high investment portion in the two short sides of the top opening 28 It consists of the structure which forms 30.

The high investment unit 30 serves to reduce the horizontal movement of the electron beam by changing the distribution of the geomagnetic field around the inner shield 20 in the direction of reducing the horizontal force, that is, Fx, by the geomagnetic field in the EW direction. 6 shows a distribution change of the EW geomagnetic field with respect to the electron beam landing on the screen diagonal portion in the inner shield according to the prior art and the inner shield according to the present embodiment.

Looking at the above graph, in the structure according to the present embodiment By represents an increased value than the conventional By 'over the entire section from R / L to the fluorescent screen, while Bz is conventional Bz near the R / L It can be seen that the value of 'reduced more than the increase of the conventional Bz' passing through the starting point of the inner shield.

Therefore, when these By and Bz are summed over the entire geomagnetic field measurement interval, and Vy and Vz are substituted into Equation 1, Fx can be determined whether or not Fx is changed. In this case, the sum of the intensities of the magnetic fields and the magnitude of Fx are compared.

Bz sum (G) By sum (G) Bz-By (G) Fx (N) Example -0.102 -0.672 0.570 6.51 × 10 ^-16 Prior art -0.664 -1.11 0.447 7.10 × 10 ^-16

As described above, the present embodiment in which the high investment portion 30 is formed at two short sides of the upper side opening 28 has increased the difference between Bz and By as compared to the prior art, but by substituting the velocity in the y- and z-axis directions of the electron beam, In the calculation, it can be seen that the EW geomagnetic field further reduces the horizontal force received by the electron beam.                     

7 is a perspective view of an inner shield according to another embodiment of the present invention, wherein the inner shield 20 forms V-notches at two short sides of the top opening 28 in the structure of the previous embodiment, A high investment portion 30 is formed along the corner.

In general, it is well known that the application of the V-notch structure to the inner shield 20 can reduce the movement of the electron beam by the NS geomagnetic field. Thus, the present embodiment provides a V-notch at two short sides of the top opening 28. By reducing the electron beam movement by the NS geomagnetic field, while forming a high investment portion 30 in the corner of the V-notch has the effect of reducing the electron beam movement by the EW geomagnetic field in the same principle as the previous embodiment.

At this time, in all the above embodiments, the high investment portion 30 provided on at least one side of the top opening 28 is preferably such that the ratio of the inner shield body portions 24 and 26 to its permeability is 1: 1.2 or more. Do.

When the ratio of the permeability between the inner shield body parts 24 and 26 and the high investment part 30 is less than 1: 1.2, the ability to cause a change in the distribution of the geomagnetic field such as the concentration of the magnetic field due to the high permeability characteristic is lowered. It is because it is difficult to expect the effect of the present invention by forming (30), that is, the reduction of the horizontal force on the electron beam.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to

 As described above, the present invention can effectively reduce the horizontal force applied to the electron beam by the N-S geomagnetic field or the E-W geomagnetic field by forming a high investment portion in at least one side of the top opening facing the electron gun. Therefore, it is possible to prevent the deterioration of screen characteristics such as other color invasion by reducing the amount of horizontal movement of the electron beam, and to improve the screen quality by improving the purity and convergence characteristics and realizing the accurate raster by guaranteeing a more accurate electron beam path. Has an advantage.

Claims (5)

A flange portion fixed to the mask frame, a pair of long side body portions and a short side body portion having a predetermined inclination such that the gap between the flange portion toward the electron gun is gradually narrowed, and an upper surface opening facing the electron gun; , At least one side of the upper opening is formed of a high permeability portion having a higher permeability than the long side and short side body portions to change the distribution of the geomagnetic field in a direction to reduce the force applied to the electron beam. The method of claim 1, The inner shield for the cathode ray tube, wherein the high investment portion is provided at two long sides of the upper opening to change the surrounding magnetic field distribution in the direction of reducing the horizontal force applied to the electron beam by the N-S geomagnetic field. The method of claim 1, The inner shield for the cathode ray tube, wherein the high investment portion is provided at two short sides of the upper opening to change the surrounding magnetic field distribution in the direction of decreasing the horizontal force applied to the electron beam by the E-W geomagnetic field. The method of claim 3, wherein An inner shield for a cathode ray tube, wherein V-notches are formed at two short sides of the upper opening, and the high investment portion is provided along an edge of the V-notch. The method of claim 1, The inner shield for cathode ray tube made of a ratio of the permeability of the long side and short side body portion and the permeability of the high permeability portion is 1: 1.2 or more.

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