KR20020085631A - Inner shield for cathode ray tube - Google Patents

Abstract

PURPOSE: An inner shield for CRT is provided to achieve improved screen quality of CRT by preventing deterioration of purity and convergence characteristics and change of raster position. CONSTITUTION: An inner shield(26) for CRT, comprises a main body(32) having a pair of longer sides(28) and a pair of shorter sides(30) formed integrally with each other, wherein the main body surrounds an electron beam path; and a flange unit(34) arranged at an aperture of panel side of the main body and fixed to a frame(20). The longer sides are bent, centering from a line(A-A) which interconnects the center of an end of the electron gun side of the longer side of the main body and the center of an end of the panel side of the longer side of the main body.

Description

Inner shield for cathode ray tube {INNER SHIELD FOR CATHODE RAY TUBE}

The present invention relates to a cathode ray tube, and more particularly, to an inner shield for a cathode ray tube that provides an inner shield having an improved structure to effectively suppress the amount of landing electron movement, particularly the amount of E-W movement of an electron beam by a geomagnetic field.

In general, electron beams traveling inside the cathode ray tube are affected by the earth's magnetic force generated by the earth's north and south poles, and are affected by purity, raster position, and convergence characteristics. do.

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. This can be explained by dividing the NS movement amount and the EW movement amount according to the direction in which the pipe is directed.

That is, as shown in Figs. 10A and 10B, the NS movement amount means the electron beam movement amount by the vertical direction (NS direction) magnetic field coinciding with the tube axis of the cathode ray tube among the horizontal geomagnetic fields, and the EW movement amount is horizontally parallel to the screen. Direction (EW direction) means the amount of electron beam movement by the magnetic field.

On the other hand, the force applied to the electron beam by the geomagnetic field can be divided into a horizontal component and a vertical component. Among these, the horizontal component mainly has a greater influence on the screen characteristics.

In the case of consumer cathode ray tubes, since the plurality of fluorescent films constituting the fluorescent screen are arranged in a vertical direction, and the shadow mask for electron beam separation forms a long slot in the vertical direction, the electron beam exerts a force in the vertical direction. This is because it is possible to land on the same fluorescent film even when it is received. However, when a force is applied in the horizontal direction, the screen characteristics are greatly deteriorated as it moves away from the designated fluorescent film.

Therefore, the inner shield is mounted inside the cathode ray tube for the purpose of reducing the amount of landing movement of the electron beam by shielding the electron beam path from the geomagnetic field. FIG. 11 shows an inner shield having a known structure.

One end of the inner shield 1 is fixed behind the mask frame 3 so as to surround the electron beam path, and is mainly made of a metal of high permeability and low magnetic force material. As a result, the inner shield 1 serves to change the distribution of the surrounding magnetic field in a direction of reducing the amount of landing movement of the electron beam by causing a kind of magnetic material to cause a cancellation or constructive interference with the geomagnetic field around the electron beam.

In relation to the function of the inner shield 1, Korean Utility Model Publication No. 98-18551 discloses a configuration in which a portion of the inner shield is partially cut in order to reduce the influence of the vertical geomagnetic field, and a domestic patent Publication No. 99-5544 discloses a configuration in which the magnetic flux is concentrated on the long, short and corner portions of the inner shield to reduce the magnetic flux density of the inner portion of the opening through which the electron beam passes.

As described above, various structures for enhancing the function of the inner shield have been devised. However, the structures have insufficient effect of suppressing the EW movement amount, and in order to suppress the EW movement amount, the piercing portion 5a, that is, the hole is formed in the long side portion 5 is known. The structure is mostly.

However, since most of the structures for reducing the EW movement amount including the piercing portion 5a tend to increase the NS movement amount, the inner shield 1 is difficult to implement a stable geomagnetic shielding function, and difficult to design a shape. It acts as a factor.

Therefore, the present invention is to solve the above problems, an object of the present invention is to provide an inner shield for cathode ray tube to effectively suppress the E-W movement amount while minimizing the increase of the N-S movement amount by changing the shape of the inner shield.

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

2 is a cross-sectional view of the cathode ray tube equipped with the inner shield shown in FIG.

FIG. 3 is a front view of the inner shield shown in FIG. 1 as seen from the electron gun direction. FIG.

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

5 and 6 are a perspective view and a front view of the inner shield according to the third embodiment of the present invention, respectively.

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

8 is a graph showing a distribution change of the E-W geomagnetic field with respect to the electron beam landing on the screen diagonal portion when the inner shield according to the present invention and the inner shield according to the present invention are mounted.

9 is a schematic diagram for explaining an electron beam movement amount measurement position.

10A and 10B are schematic diagrams for explaining the N-S movement amount and the E-W movement amount.

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

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

A pair of long sides and a pair of short sides have a predetermined slope and are integrally fixed to enclose an electron beam path, and a flange portion provided at a panel side opening of the body to be fixed to a frame,

Provided is an inner shield for a cathode ray tube having at least one body portion bent with respect to a center line connecting a center of one end of an electron gun side and a center of one end of a panel side.

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

1 is a perspective view of an inner shield according to a first embodiment of the present invention, Figure 2 is a cross-sectional view of the cathode ray tube mounted with the inner shield.

As shown in the drawing, the cathode ray tube is integrally fixed with the panel 2, the funnel 4, and the neck portion 6 to form a vacuum bulb 8, and the panel 2 has a plurality of R, G on its inner surface. And a fluorescent screen 10 made of a B fluorescent film, and fixing the color screening device 12 therein. The funnel 4 and the neck portion 6 are integrally mounted with the deflection yoke 14 and the electron gun 16 to the outside and the inside thereof, respectively.

The color screening device 12 includes a mask 18 having a plurality of beam passing apertures 18a formed therein, and a frame 20 supporting the beam sorting device. That is, in the tension type, the mask 18 is fixed to the support member 22 of the frame 20 in a state in which the mask 18 is mainly stretched in the direction of the vertical axis (y-axis in the figure) of the screen, and the rigid member 24 is the mask 18. It supports the tensile force of.

The color screening device 12 is fixed inside the panel 2 by fixing means (not shown), and the inner shield 26 is fixed to the opposite end of the frame 20 to be mounted inside the cathode ray tube to surround the electron beam path. do.

With the above-described configuration, when the electron gun 16 emits a three-stem electron beam corresponding to the screen signal, the electron beam is deflected by the magnetic field in which the deflection yoke 14 is generated to form a raster on the screen while forming a raster on the screen. This causes the R, G, and B fluorescent films to land and emit all the pixels in a specified color.

As a result, the electron beam forms a raster specified by the deflection magnetic field, and the three-beam electron beam must be moved along the designated path to exactly match (i.e., achieve good convergence characteristics) in one beam passing aperture 18a. Color implementation is possible.

Therefore, the inner shield 26 serves to shield the geomagnetic field that affects the electron beam movement to a certain level. In particular, the present embodiment can effectively reduce the EW movement amount while minimizing the NS movement amount in addition to the basic geomagnetic shield function. Provide inner shield with new configuration.

FIG. 3 is a front view of the inner shield shown in FIG. 1 viewed from the electron gun direction, and the inner shield 26 includes a pair of long sides 28 surrounding the upper and lower portions of the electron beam path and a pair of left and right portions of the left and right portions of the electron beam path. And a flange portion 34 provided at the panel side opening of the body portion 32 and fixed to the frame 20, wherein the long side portion 28 is formed. It is formed in a shape bent with respect to the center line AA for dividing it to the left and right.

That is, the center line AA bisecting the long side portion 28 is a line connecting the center point of one end of the electron gun side of the long side portion 28 and the center point of one end of the panel side, and the long side portion 28 refers to this center line. It is bent in a symmetrical shape, in particular in the inner shield 26 is made of a shape bent toward the inside.

As a result, the pair of long sides 28 is composed of two faces symmetrical with respect to the center line, while the pair of short sides 30 is composed of a single face, wherein each of the long sides 28 has a center line and A plurality of piercing portion 28a formed to be parallel may be formed.

In particular, the long side portion 28 is closer to the electron beam path by having the displacement t ₁ compared to the inner shield of the known structure at the center of one end of the electron gun side by the bent shape described above. Therefore, the bent shape of the long side portion 28 is preferably made with a sufficient margin so that the electron beam emitted from the electron gun 16 does not collide with the long side portion 28.

As the pair of long side portions 28 are bent toward the inner shield 26, the inner shield 26 provides magnetic resistance with respect to the EW direction so that the electron beam is generated by the geomagnetic field in the EW direction. The geomagnetic field distribution around the inner shield 26 is changed in the direction of reducing the force in the horizontal direction.

In this case, the angle formed by the two surfaces of the long side portion 28 of the inner shield 26 is preferably 120 ° or more, which is t shown in FIG. 3 when the angle formed by the two sides of the long side portion 28 is 120 ° or less. This is because a value of ₁ may increase to interfere with the path of the electron beam.

In addition, as the inner shield 26 is shown in FIG. 4 as a second embodiment, the V-notch 30a is formed on a pair of short sides 30 having a single surface in the configuration of the previous embodiment, and thus NS is formed. The amount of movement can be reduced.

5 is a perspective view of an inner shield according to a third embodiment of the present invention, and FIG. 6 is a front view of the inner shield shown in FIG. 5, wherein the inner shield 26 is not only a pair of long sides 28 but also a pair of short sides. The part 30 also has a shape that is bent based on the center line BB that divides it up and down.

That is, the pair of short sides 30 are bent symmetrically based on the center line B-B, and in particular, the pair of short sides 30 are bent toward the outside of the inner shield 26 as opposed to the long sides 28.

At this time, the displacement of t ₂ at the center of one end of the electron gun side due to the shape of the short side portion 30 is such that one end of the short side portion 30 does not come into contact with the inner surface of the funnel 4. It may be formed in size, and the angle formed by the two surfaces of the short side portion 30 is preferably 120 ° or more so as to prevent contact with the funnel 4 and not cause interference in the electron beam path.

Thus, the inner shield 26 is composed of two pairs of both sides of the pair of long side portions 28 and the short side portions 30 are symmetrical with respect to their centerline, and the long side portion 28 is similar to the above-described embodiment. ), A plurality of piercing parts 28a parallel to the center line AA may be formed.

At this time, the inner shield 26 forms a V-notch 30a on the pair of short sides 30 that are bent toward the outside of the inner shield 26 as shown in FIG. 7 as a fourth embodiment. The amount of movement can be reduced.

As the pair of short sides 30 is bent toward the outside of the inner shield 26, the short sides 30 are formed along with the long sides 28, and the electron beam is formed by a geomagnetic field in the EW direction. It serves to change the geomagnetic field distribution around the inner shield 26 in the direction of reducing the force in the horizontal direction.

In more detail, the horizontal force Fx (N) applied to the electron beam by the external geomagnetic field may be expressed by the following equation (1).

Fx = -e (VyBz-VzBy)

Here, e represents the charge amount C, Vy and Vz represent the y-direction and z-direction velocity (m / s) of the electron beam, respectively, and By and Bz represent the magnitude T of the y-direction and z-direction geomagnetic field components, respectively.

As shown in the above equation, the horizontal force on the electron beam is determined by the magnitude of the geomagnetic field formed around the electron beam, i.e., the Bz and By values, with a constant velocity of the electron beam, in particular proportional to the difference between Bz and By. It can be seen.

Therefore, the inner shield 26 according to the present embodiment has a shape in which at least one body portion is bent to reduce the absolute value of Fx as the By and Bz magnetic field distributions are changed. In the shield and the inner shield according to the fourth embodiment of the present invention, the distribution of the EW magnetic field for the electron beam landing on the screen diagonal is shown.

Here, as shown in FIG. 11, the inner shield according to the conventional structure has a pair of long side portions 5 and short side portions 7 all formed in a single surface, and both the conventional structure and the present embodiment have the same material as those body parts. And the same size were used.

As a result, the By 'and Bz' distribution when the inner shield is mounted according to the conventional structure 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 ( 16) means the distance on the tube axis (z-axis in the figure) to the fluorescent film screen 10, the vertical axis represents the intensity of the magnetic field.

In particular, the reference line (R / L) on the horizontal axis is a point at which the angle formed between the straight line and the tube axis is the maximum deflection angle when a straight line is drawn from the diagonal axis of the panel (2). The 0.0 mm point means the starting point of the inner shield in which the electron gun side opening of the inner shield 26 is located.

The magnetic field strength having a negative value on the vertical axis means that the magnetic field is distributed in a direction opposite to the positive direction indicated by the arrow ends of the y-axis and z-axis shown in FIG. 1.

Therefore, looking at the change in the distribution of the geomagnetic field shown in the graph, In the structure according to the present embodiment By represents an increased value than By 'of the conventional structure over the entire section from R / L to the fluorescent screen 10.

In the structure according to the present embodiment, Bz shows a pattern that increases after decreasing as compared with Bz 'of the conventional structure. As a result, when comparing the sum of them throughout the geomagnetic field measurement interval, Bz according to the present embodiment shows a value similar to or slightly increased from Bz 'of the conventional structure.

Therefore, as defined in Equation 1, since the By increase in the structure of the present embodiment is much larger than the increase in Bz, the difference between Bz and By can be reduced to effectively reduce the absolute value of Fx.

Table 1 below shows an inner shield having a long side portion and a short side portion having a single surface, a first embodiment of the present invention in which the long side portion 28 is bent (test 1), the long side portion 28 and the short side portion. Fig. 30 shows data obtained by measuring the electron beam shift amount in the third embodiment (test 2) of the present invention, in which all of the parts (30) were bent.

Measuring position Conventional structure Test 1 Test 2 N-S travel amount H 100.0 100.0 102.0 V 100.0 100.6 101.1 D 100.0 86.4 93.0 E-W travel amount H 100.0 100.0 100.0 V 100.0 100.0 100.0 D 100.0 71.1 70.0

In the above table, the electron beam movement amount measurement is made at the horizontal end H, the vertical end V, and the diagonal end D of the screen, as shown in FIG. The measured value is expressed as a ratio thereof when the electron beam shift amount is assumed to be 100 in the conventional structure.

As can be seen from the above table, the first embodiment of the present invention (test 1) in which the long side portion 28 is bent has the effect of reducing the N-S movement amount and the E-W movement amount by 13.7% and 28.9%, respectively, at the diagonal ends. On the other hand, the N-S movement amount and the E-W movement amount at the horizontal and vertical ends show no increase or almost insignificance.

In addition, the third embodiment of the present invention (test 2) formed by bending both the long side portion 28 and the short side portion 30 showed a tendency to slightly increase the NS movement amount at the horizontal and vertical ends, and the NS movement amount at the diagonal ends. And 7% and 30% reductions in both EW shifts.

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 the range of.

As described above, the inner shield of the present invention has a shape in which a pair of long sides are bent toward the inside of the inner shield, or in addition, the pair of short sides is bent toward the outside of the inner shield. This reduces the E-W movement by minimizing the increase of N-S movement by changing the distribution of the geomagnetic field around the electron beam, and in particular, reduces both the N-S movement and the E-W movement at the diagonal ends.

Therefore, it has the advantage of effectively improving the image quality of the cathode ray tube, in particular the image quality characteristics at the diagonal end by suppressing the degradation of the purity characteristics and convergence characteristics due to the geomagnetic field, raster position change.

Claims (7)

A pair of long sides and a pair of short sides have a predetermined slope and are integrally fixed to enclose an electron beam path, and a flange portion provided at a panel side opening of the body to be fixed to a frame, An inner shield for a cathode ray tube having at least one body part bent with respect to a center line connecting a center of one end of an electron gun side and a center of one end of a panel side. The method of claim 1, An inner shield for a cathode ray tube made of a shape in which the long side portion is bent. The method of claim 2, The inner shield for the cathode ray tube of the long side portion is formed in a shape bent toward the inner shield. The method of claim 2, An inner shield for a cathode ray tube in which a V-notch is formed in the short side portion. The method of claim 2, An inner shield for a cathode ray tube having a long side portion and a short side portion is bent. The method of claim 5, An inner shield for cathode ray tubes, wherein the short side portion is bent toward the outside of the inner shield. The method of claim 5, An inner shield for a cathode ray tube in which a V-notch is formed in the short side portion.