KR20020091725A - Flat cathode-ray tube containing improved shadow mask - Google Patents

Abstract

PURPOSE: A flat CRT having an improved shadow mask is provided to reduce a stretching error and increase a purity margin of an edge of a screen by optimizing a structure of a non-effective screen area of a shadow mask. CONSTITUTION: A fluorescent layer is formed on an inner face of a panel. A funnel is combined with the panel. An electron gun is mounted on a neck portion of the funnel in order to emit electron beams to the fluorescent layer. A shadow mask is arranged at a predetermined position from the fluorescent layer of the inner face of the panel in order to perform a dichroic function. A frame is used for supporting the shadow mask. The shadow mask is formed with an effective screen area(13) and a non-effective screen area(14). A plurality of electron beam passing holes are formed on the effective screen area(13). The shadow mask satisfies a relationship of 1.3<=Ix/Iy<=2.5 and 0.9<=Ir/Iy<=1.2 where Ix is width of an X-axis direction of the non-effective screen area(14), Iy is width of a Y-axis direction of the non-effective screen area(14), and Ir is width of a diagonal axis of the non-effective screen area(14).

Description

Flat cathode-ray tube containing improved shadow mask

The present invention relates to a flat CRT, and in particular, to optimize the structure of the ineffective surface of the shadow mask for a flat CRT, to equalize the amount of movement of the electron beam through hole located on the same axis of the edge of the mask effective surface after stretching to minimize stretching defects The present invention relates to a planar CRT which increases the quality of the CRT by increasing the degree of purity of the edge of the CRT.

In the conventional flat CRT, as shown in FIG. 1, the fluorescent surface 1 of R, G, and B is coated on the inner side, and the panel 3 on which the explosion-proof glass 2 is fixed on the front side, and the panel A funnel (4) fused at the rear end of the nozzle, an electron gun (7) enclosed in the neck portion of the funnel to emit an electron beam, and a shadow having a plurality of holes formed at regular intervals inside the panel to allow the electron beam to pass through A mask 8, a rail 9 for tensioning and supporting the shadow mask so that the shadow mask is kept at a constant distance from the inner surface of the panel, and an inner shield 10 for shielding the cathode ray tube from being affected by external geomagnetism. And a reinforcing band 11 installed around the side portion of the panel to prevent external impact.

And there is a magnet (Magnet) to correct the trajectory so that the electron beam strikes a predetermined phosphor accurately, thereby preventing the poor color.

Reference numeral 12 is a deflection yoke.

In the planar CRT, a doming phenomenon occurs in which the shadow mask 8 thermally expands due to thermal energy generated by collision with an electron beam emitted from the electron gun 7 during operation.

In order to prevent the doming phenomenon, there is a method of improving the thermal conductivity by using a material having a low deformation at a high temperature or by increasing the thickness of the mask, but these two methods have a disadvantage of increasing the unit cost of the product.

Therefore, in order to lower the product cost, the shadow mask is generally made of 0.025 to 0.050 mm of general steel, and the shadow mask is artificially moved in the long axis (x axis) and short axis (y axis) directions to prevent the doming phenomenon. Thermal strain is prevented by using residual stress such as tensioning. However, according to the tensile condition and the screen condition, high shadow and stress are locally applied to the shadow mask, so that the shape of the through-hole in the mask is deformed or fracture occurs due to stress concentration.

The general shadow mask as shown in FIGS. 2A to 2C is analogous to an effective part 13 including an electron beam through hole corresponding to a fluorescent surface and a stress damping hole 16 for attenuating stress concentrated in the through hole during stretching. It is divided into the effect 14, and the outermost portion of the through hole there is a reference hole 15 which is a reference value of the displacement value when stretching the mask. The reference hole is provided at eight corners of the outermost portion of the mask effective surface and in the directions of 12, 9, 6 and 3 o'clock.

The bonding method between the conventional shadow mask 8 and the frame 9 fixedly supporting the same is as follows. First, the applied fluorescent surface coincides with the shadow mask, and the reference hole is moved vertically and horizontally by a desired position. Then, the stretched mask is brought into contact with the panel coated with the phosphor, and then welded to the upper surface of the frame with a laser welder.

As such, in the related art, a method of stretching the shadow mask while controlling the reference hole in the vertical direction from the outside to the desired position is used. The through hole, the stress damping hole, and the reference hole have a shape, The size and position vary.

In addition, conventionally, the size of the through hole in the mask effective surface is reduced from the center to the outside to prevent the concentration of stress in the through hole during stretching.

However, in the related art, since the stretching is performed based on the reference holes located at the eight locations, local deformation occurring at the outer edge of the mask cannot be controlled. In addition, such poor stretching uniformity causes mis-landing for each location or local color degradation due to reduced color purity margin.

In order to control this phenomenon, various methods have been attempted, such as retrofitting a stretching machine to install a reference hole in addition to the existing reference hole and to add a grip for stretching accordingly, but have not obtained obvious results.

In addition, the material of the conventional shadow mask exhibits anisotropic physical properties during rolling, especially in the shadow mask having a slot shape of a through hole. In the slot type shadow mask, in particular, in the x-axis (long axis) and y-axis (short axis) directions, poor stretching occurs frequently at the corners where external loads are applied. That is, the displacement increases in the + y direction when stretching in the y-axis direction, while the displacement increases in the -x direction when stretching in the x-axis direction. Therefore, the reference hole of the shadow mask is moved in the -x direction, and to correct this, the reference hole is moved to a desired position by increasing the stretching in the x-axis direction. At this time, the reference hole has been moved to a desired position, but as shown in FIG. 4, stretching defects of about 0.01 to 0.02 nm with respect to the design value occur in the periphery of the reference hole.

Therefore, the present invention optimizes the structure of the non-effective surface of the flat shadow shadow mask for a flat CRT tube to equalize the amount of movement of the electron beam through-holes located on the same axis of the edge of the mask effective surface after stretching to minimize stretching defects and the margin of purity of the edge of the screen. It is aimed at improving the picture quality of the CRT by increasing.

1 is a cross-sectional view of a flat CRT tube of the prior art,

Figure 2a to c is a shape diagram of a tension mask of the prior art,

3 is a diagram showing a relationship between stress and displacement in a mask hole;

4 is a view showing the shape of the slot after stretching of the tension mask of the prior art and

5 is a shape diagram of a tension mask of the present invention.

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

DESCRIPTION OF SYMBOLS 1 Panel 2 Funnel 3 Shadow mask 4 Fluorescent surface

7 Frame 12 Electron Beam Passing Hole 14 Effective Surface 15 Skirt

The technical means of the present invention for achieving this object is a panel having a fluorescent surface on the inner surface, a funnel connected to the panel, an electron gun mounted on the neck portion of the funnel and emitting an electron beam toward the fluorescent surface, In a flat CRT including a shadow mask disposed at a predetermined interval with respect to the fluorescent surface to serve as color screening, and a frame supporting and fixing the shadow mask by applying tension to the shadow mask, wherein the shadow mask has an electron beam passing hole corresponding to the fluorescent surface. An effective surface having an electron beam passing hole not corresponding to the fluorescent surface; When the width in the x-axis direction (long axis direction) of the ineffective surface is lx, the width in the y-axis direction (short axis direction) is ly, and the width in the diagonal axis direction is lr, the following equation is satisfied.

In addition, the corner portion of the ineffective surface is characterized in that it has the shape of an arc.

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

The present invention used the following method to optimize the distance by setting the distance in the x-axis, y-axis direction of the ineffective surface as a design factor to solve the problem centering each corner of the most unbalanced shadow mask.

First, find the effective property value of the unit slot. As shown in FIG. 3, a unit load is applied to the unit slot form to obtain displacement values in the x and y axis directions. The displacement value is determined by using the analysis version 5.6, which is a general application because it is not only dependent on the nicking state of the slot, but also because the size of the slot is very small.

The displacement values obtained above are converted and calculated to obtain the effective physical properties of each displacement value. Since the physical properties vary depending on the shape of the slot, the physical properties may have different values for each location. However, the physical properties may be designed with the physical properties of the corners because most problems occur around the corners. Physical properties of the corners are as follows.

Ex = 5.2E4 MPa

Ey = 1.58 E5 MPa

Ey-Ex = 1.0E5 MPa

Ex is an elastic modulus in the 3-9 o'clock direction, that is, a horizontal direction with respect to the screen, and Ey is an elastic modulus in the 6-12 o'clock direction, that is, perpendicular to the screen. As can be seen from the above properties, in the case of stripe type slots, the stretching ratio for the same external load is higher in the y-axis direction than in the x-axis direction.

Next, the displacement equation of the x-axis direction at the time of application of the unit load in the y-axis direction is formed using the obtained effective physical property value. In order to show the influence on the x-axis direction when stretching in the y-axis direction, the anisotropy of the material and the anisotropy due to the slot shape are shown as follows.

From above Is the displacement change in the horizontal direction that occurs during vertical stretching of the shadow mask, Is the vertical length of the shadowmask ineffective face, Is the horizontal length of the ineffective face, Is the diagonal length of the ineffective face, Is Poisson Ratio, which represents the difference in displacement in the vertical and horizontal directions caused by the slot when the shadow mask is stretched, Is a Poisson's ratio showing the anisotropy characteristic according to the shape of the shadow mask thin plate raw material grain (Grain).

Finally, the optimum ineffective surface distance is derived by comparing the displacement equation obtained above with the displacement value in the x-axis direction when the unit load is applied in the x-axis direction. As a result, the shape of the ineffective surface closest to the effective surface of each corner has a distance of 1.3 to 2.5 times the distance between the ineffective surface in the x-axis direction and the y-axis. The most favorable result was obtained for resolving the nonuniformity.

In the above formula, lx represents the width of the ineffective surface in the x-axis direction (long axis direction), and ly represents the width of the y-axis direction (short axis direction).

In addition, the corner portion of the ineffective surface where the stress is concentrated is formed in the shape of an arc to reduce the conventional local concentrated stress value to the maximum, thereby improving the local stretching uniformity. At this time, the ineffective surface of the arc shape is preferably formed in the range of the following formula.

In the above formula, lr represents the width of the diagonal axis direction of the ineffective surface, and ly represents the width of the y axis direction (short axis direction).

The present invention has optimized the width of the non-effective surface of the shadow mask in the x-axis and y-axis directions to improve the non-uniformity generated during the stretching of the shadow mask. The conventional localized concentrated stress value was reduced by about 200 MPa, and thus, the local stretching uniformity was improved to less than 0.005 mm compared with the conventional method.

Claims (4)

A panel having a fluorescent surface on the inner surface, a funnel connected to the panel, an electron gun mounted on a neck portion of the funnel to emit an electron beam toward the fluorescent surface, and arranged at a predetermined interval with respect to the fluorescent surface on the inner surface of the panel, and performing color screening. In the planar CRT comprising a shadow mask to the frame, and a frame for fixing by applying tension to the shadow mask, The shadow mask is composed of an effective surface having an electron beam passing hole corresponding to the fluorescent surface and an invalid surface having an electron beam passing hole not corresponding to the fluorescent surface; And a width in the x-axis direction (long-axis direction) of the ineffective surface as lx and a width in the y-axis direction (short-axis direction). A panel having a fluorescent surface on the inner surface, a funnel connected to the panel, an electron gun mounted on a neck portion of the funnel to emit an electron beam toward the fluorescent surface, and arranged at a predetermined interval with respect to the fluorescent surface on the inner surface of the panel, and performing color screening. In the planar CRT comprising a shadow mask to the frame, and a frame for fixing by applying tension to the shadow mask, The shadow mask is composed of an effective surface having an electron beam passing hole corresponding to the fluorescent surface and an invalid surface having an electron beam passing hole not corresponding to the fluorescent surface; And a width in the diagonal axis direction of the ineffective surface lr and a width in the y-axis direction (short axis direction) ly satisfying the following equation. The method of claim 2, A flat CRT tube, wherein the corner portion of the ineffective surface has a circular arc shape. The method according to claim 1 or 2, A flat CRT tube, characterized in that the inner surface and the outer surface of the panel is in a flat flat form, and the frame attached to the flat panel is a rail.