KR20030025456A - A Flat Type Color Cathode Ray Tube - Google Patents

Abstract

PURPOSE: A flat color cathode ray tube is provided to reduce the weight of the cathode ray tube by reducing the wedge ratio of the panel, while reducing the thermal breakdown by improving the structure of the panel. CONSTITUTION: A flat color cathode ray tube comprises a panel(1) having a substantially flat outer surface, an inner surface with a curvature, and a skirt extended from the outer and inner surfaces; and a shadow mask(3) having a plurality of electron beam passing holes formed at the inner surface of the panel. The panel has a transmissibility of 75% or lower, and a wedge ratio of 170 to 190%, wherein the wedge ratio is the ratio of the thickness of the center of the panel to the thickness of the edge of the panel. The conditions 1.3<RPH/RMH<2.0, 1.0<RPV/RMV<1.4, 1.3<RPD/RMD<2.0 are satisfied, wherein RPH is the longer side direction curvature of the inner surface of the panel, RPV is the shorter side direction curvature of the inner surface of the panel, RPD is the diagonal direction curvature of the inner surface of the panel, RMH is the longer side direction curvature of the shadow mask, RMV is the shorter side direction curvature of the shadow mask, and RMD is the diagonal direction curvature of the shadow mask.

Description

Flat Cathode Ray Tube

The present invention relates to a flat color cathode ray tube, and more particularly, a shadow mask capable of maintaining the impact strength while reducing the breakage rate in the furnace during the manufacturing process by reducing the thickness ratio of the outer thickness to the center thickness of the flat panel. It is about structural improvement.

1 is a view showing a schematic configuration of a general color cathode ray tube, in which a front glass called a panel 1 and a rear glass called a funnel 2 are combined, and an inner surface of the panel 1 has a fluorescent surface which plays a predetermined light emitting role. It consists of an electron gun which is the source of the electron beam 11 which emits a fluorescent surface, and a shadow mask 3 for sorting colors to emit a predetermined phosphor, and a main frame 5 supporting the shadow mask 3.

A spring 6 for coupling the main frame 5 on which the shadow mask 3 is mounted to the panel and an inner shield 7 for shielding the cathode ray tube less influenced by external geomagnetism during operation are provided in the main frame. It is fixed to 5) and sealed by high vacuum.

Referring to the operation principle of the color cathode ray tube disclosed in Figure 1 as follows. In the electron gun embedded in the neck of the funnel 2, the electron beam 11 strikes the fluorescent surface formed on the inner surface of the panel 1 by the anode voltage applied to the cathode ray tube, before the electron beam reaches the fluorescent surface. The deflection yoke 9 is deflected up and down and left and right to form a screen.

In addition, since such a cathode ray tube is made of high vacuum, firecrackers can easily occur due to external impact, and the panel 1 is designed to have a structural strength capable of withstanding atmospheric pressure in order to prevent this. In addition, the reinforcing band 12 is mounted on the outer surface of the skirt 1 of the panel 1 to disperse the stress of the cathode ray tube in a high vacuum state and to secure impact resistance.

The conventional cathode ray tube is largely composed of a panel 1 and a funnel 2, and an electron gun is inserted into the neck portion of the funnel 2 to form a vacuum state and be sealed by an exhaust process. Here, when the bulb is in a vacuum state, the panel 1 and the funnel 2 are subjected to considerable tensile and compressive forces. This phenomenon results in excessive tensile stress values at certain locations on the screen of panel 1.

At present, the panel 1 is in a trend of being enlarged and planarized. 2A and 2B show a panel form having both curvature inside and outside and a planar panel form having almost no curvature on the outer surface, and the thickness of the panel is increased, which increases the weight of the panel and increases the manufacturing cost of the panel. The disadvantages arise due to the enlargement of parts such as.

FIG. 3 illustrates a flat panel structure having no curvature on the left side and a non-planar panel structure having curvature on both the inner and outer surfaces on the right side, wherein the flat panel has a distance (OMH) from the mold match line to the right edge. It is formed larger than the non-planar panel. As described above, the conventional flat panel has a structure in which the overall thickness is increased, so that the panel's limit stress due to the thermal change of the inner and outer surfaces is basically limited due to the difference in the thermal conductivity of the panel in the furnace.

In general, dark tint glass, which contains a small amount of black dye in glass, is used to improve the contrast of the cathode ray tube. Low transmittance The wedge rate of the general planar cathode ray tube is 200% or more, and when the dark tint glass is used, there is a problem in that the luminance balance becomes worse due to the difference in transmittance at the outer side compared to the center portion.

In addition, there is a problem in that the weight of the panel increases and the amount of glass material used for the panel increases as the wedge rate increases.

In order to solve the problems of in-furnace breakage, decrease in transmittance, increase in weight, and increase in glass material usage due to the increased wedge rate of the flat panel as described above, in order to reduce the wedge rate, the outer surface of the panel is almost flat and the inner radius of curvature is reduced. It is possible to increase it. However, the shadow masks arranged at regular intervals on the inner surface of the panel should be deformed in accordance with the curvature of the inner surface of the panel. In order to increase the radius of curvature of the panel, the radius of curvature of the shadow mask must be increased. Therefore, the wedge ratio of the panel is lowered because the structural strength of the shadow mask is weak, which lowers the impact resistance and howling characteristics due to external impact. I could not.

Accordingly, an object of the present invention is to provide a planar cathode ray tube having a good structural strength of a shadow mask while lowering the wedge ratio of the panel to solve the problems of increased furnace breakage, lower transmittance, increased weight, and increased glass material usage. have.

1 is a cross-sectional view schematically showing the configuration of a general color cathode ray tube;

2A and 2B illustrate a panel having an outer surface curvature and a flat panel structure having almost no curvature,

3 is a diagram showing a skirt portion structure of a flat panel and a curvature panel;

4 is a diagram showing the major axis, the minor axis, and the diagonal axis curvature of the panel and the shadow mask;

5 is a view showing a pitch change of the electron beam through hole of the shadow mask according to the present invention, and

6 is a graph showing the change in X-ray transmittance according to the center thickness of the panel.

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

1: Panel 2: Funnel

3: shadow mask 5: mainframe

7: inner shield 8: gun

9: deflector

Technical solution of the present invention for achieving the above object, the outer surface is substantially flat, the inner surface has a constant curvature, the rectangular panel having a skirt extending substantially perpendicular to the inner and outer surface and constant on the inner surface of the panel In a flat color cathode ray tube including a shadow mask having a large number of electron beam through holes arranged at intervals, the panel has a transmittance of 75% or less and a wedge ratio of 170 to an outer thickness ratio to the thickness of the center portion of the panel. 190%, preferably 180%, the long axis curvature of the inner surface of the panel R _PH, the short axis curvature of the inner surface of the panel R _PV, the diagonal direction curvature of the inner surface of the panel R _PD, the long axis of the shadow mask When the curvature is R _MH, the unidirectional curvature of the shadow mask is R _{MV, and} the diagonal mask curvature of the shadow mask is R _MD , 1.3 <R _PH / R _MH <2.0, 1.0 <R _PV / R _MV <1.4 , And 1.3 <R _PD / R _MD <2.0.

In addition, the pitch of the electron beam through-hole increases from the central portion of the shadow mask toward the periphery in at least one of the major axis direction, the minor axis direction, and the diagonal axis direction to compensate for the change in the Q value, which is the distance between the shadow mask and the inner surface of the panel. It is desirable to.

More specifically, the pitch of the electron beam through hole of the shadow mask is Ph _O , the pitch of the electron beam through hole in the center of the shadow mask is Ph _H , and the pitch of the outermost electron beam through hole in the short axis direction is Ph _V , When the pitch of the outermost electron beam passing hole in the diagonal direction is Ph _D , it is preferable that 1.2 <Ph _O / Ph _H <1.5, 1.0 <Ph _O / Ph _V <1.3, 1.2 <Ph _O / Ph _D <1.5.

The panel is dark tint glass and can improve contrast.

The center thickness (CFT) of the panel can be 11 to 13 mm to reduce the weight of the panel.

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

The present inventors have analyzed the cause of the problem of the conventional flat brown tube (hereinafter referred to as 'FCD') being too heavy and having high thermal process breakage rate during the manufacturing process. As a result, the FCD has almost a flat outer surface and a constant curvature inside the panel. The thickness of the effective screen edge (wedge rate) is thicker and thicker than that of the center, and the breakage in the furnace increases in the thermal process.

As shown in FIG. 4, the FCD of the present invention uses dark tint glass having a panel transmittance of 75% or less to improve contrast, and has a panel plane curvature radius of the panel of 30,000 R or more in a substantially flat surface. The inner surface has an effective screen tip thickness (wedge rate) of 5440.4 mm in long axis curvature (R _PH ), 2289 mm in short axis curvature (R _PV ) and 4819 mm in diagonal axis curvature (R _PD ). Is reduced to about 180% from conventional 200%. In the present invention, the ratio of the effective screen end thickness (wedge rate) to the center of the panel is not limited to the 180%, and it is 170 to 190% to reduce the breakage rate in the furnace during the heat treatment process and to reduce the absolute weight.

At the same time, the radius of curvature of the shadow mask according to the present invention is designed to be smaller than the radius of curvature of the panel described above to maintain the structural strength of the shadow mask. That is, the axial curvature R _{MH of the} shadow mask is 2749.8 mm, the axial curvature R _{MV of} the shadow mask is 1746 mm, and the diagonal axial curvature R _MD of the shadow mask is 2511.5 mm.

That is, the ratio of the long axis, short axis, and diagonal axis curvature of the shadow mask to the long axis, short axis, and diagonal axis curvature of the panel satisfies the following equation.

1.3 <R _PH / R _MH <2.0.. (One)

1.0 <R _PV / R _MV <1.4.. (2)

1.3 <R _PD / R _MD <2.0.. (3)

Therefore, as described above, when the radius of curvature of the shadow mask is smaller than the radius of curvature of the panel, the Q value, which is an interval between the shadow mask and the inner surface of the panel, becomes gradually larger from the center portion to the outer portion. As such, the pitch of the shadow mask is increased from the center to the outside to compensate for the problem caused by the increase in the deflection distance of the electron beam colliding with the outside of the panel due to the increase of the Q value, which is the distance between the shadow mask and the inner surface of the panel. The center-side Q value is 17.50 mm, the Q value of the major axis periphery is 24.33 mm, the Q value of the minor axis perimeter is 20.44 mm, and the Q value of the diagonal axis perimeter is 28.89 mm.

As shown in FIG. 5, the electron beam through hole pitch of the shadow mask is 0.75 as the electron beam through hole pitch Ph _{0 at} the center of the shadow mask, and 0.98 mm as the electron beam through hole pitch Ph _{H in the} outermost direction in the long axis direction. , The outermost electron beam through hole pitch Ph _V is 0.80 mm, and the outermost electron beam through hole pitch Ph _D is 1.02 mm. The pitch of the electron beam through holes of the shadow mask is just described as a preferred example, and the following expression may be satisfied to compensate for the increase in the Q value of the outer side.

1.2 <Ph _O / Ph _H <1.5... (4)

1.0 <Ph _O / Ph _V <1.3... (5)

1.2 <Ph _O / Ph _D <1.5... (6)

The use of dark tint glass as a panel to improve contrast with respect to the panel having the above-described structure is preferable because the difference in transmittance between the center and the outside can be reduced by reducing the wedge ratio, thereby preventing the luminance nonuniformity.

In addition, the reduction of the panel weight is determined by the panel center thickness (CFT: shown in FIG. 3) as well as the wedge rate of the panel, which should be designed in consideration of the X-ray transmittance.

In general, the color cathode ray tube causes the X-ray to penetrate the panel due to the emission of the electron beam by the electron gun. Although this amount is small, the upper limit is set as a standard for safety. X-rays vary greatly with anode voltage, for example, should be less than 0.5 mR / h at about 41 KV. In the graph shown in FIG. 6, when the absolute value of the CFT is 11 mm, the safety of the X-ray cannot be guaranteed. On the contrary, if the absolute value of the CFT exceeds 13mm, the safety of the X-rays can be sufficiently secured, but the weight loss of the panel is minimal.

As described above, according to the present invention, there is an effect of reducing the wedge ratio of the panel to reduce the weight of the planar cathode ray tube and reduce the thermal damage in the furnace due to the improvement of the structure of the panel. At the same time, the provision cost can be reduced due to the reduction of the glass material cost in panel production. In addition, due to the reduction of the wedge rate, the brightness of the screen is improved, and the contrast can be improved by using a high-quality panel such as dark tint glass.

In particular, it is possible to satisfy the drop characteristic improvement and the howling characteristic improvement of the planar cathode ray tube by solving the problem of lowering the structural strength of the shadow mask according to the flattening of the inner surface of the panel.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made within the technical scope of the present invention, and such modifications and modifications belong to the appended claims.

Claims (5)

A shadow panel having a substantially flat outer surface, a constant curvature, a rectangular panel having a skirt extending approximately perpendicular to the inner and outer surfaces, and a large number of electron beam through holes arranged at regular intervals on the inner surface of the panel. In the planar color cathode ray tube comprising a mask, The panel has a transmittance of 75% or less, a wedge ratio of 170 to 190% of the thickness of the outer portion to the thickness of the center portion of the panel, The long axis curvature of the inner surface of the panel is R _PH, The short axis curvature of the inner surface of the panel is R _PV, The diagonal axis curvature of the inner surface of the panel is R _PD, The long axis curvature of the shadow mask is R _MH, The short axis of the shadow mask And directional curvature R _{MV, and} the diagonal mask curvature of the shadow mask is R _MD , wherein the following formula satisfies: 1.3 <R _PH / R _MH <2.0, 1.0 <R _PV / R _MV <1.4, 1.3 <R _PD / R _MD <2.0 The method of claim 1, And a pitch of the electron beam passing hole increases from a central portion of the shadow mask toward a peripheral portion in at least one of a major axis direction, a short axis direction, and a diagonal axis direction. The method of claim 2, The pitch of the electron beam passing hole in the center of the shadow mask is Ph _O , the pitch of the outermost electron beam passing hole is Ph _H , the pitch of the outermost electron beam passing hole is Ph _V , and the pitch of the outermost electron beam passing hole is in the diagonal direction. When the Ph _D , a flat color cathode ray tube, characterized in that to satisfy at least one of the following formula. 1.2 <Ph _O / Ph _H <1.5 1.0 <Ph _O / Ph _V <1.3 1.2 <Ph _O / Ph _D <1.5 The method of claim 1, And the wedge rate of the panel is 180%. The method of claim 1, And the center portion thickness (CFT) of the panel is 11 to 13 mm.