KR20000013714A - Color cathode ray tube - Google Patents

Abstract

PURPOSE: A color cathode ray tube is provided to improve a color purity of a periphery of a fluorescent plane without dropping a brightness. CONSTITUTION: The color cathode ray tube comprises: a panel having R, G and B fluorescent planes; a funnel attached at a rear stage of the panel; an electron gun inserted in a neck part of the funnel; a deflection yoke for deflecting an electronic beam so that the electronic beam from the electron gun strikes an entire plane of the fluorescent planes; a frame supported inside the panel; a shadow mask in which electron beam through hole of a dot shape are arranged so as to pass the electronic beam and supported by the frame; and a spring mounted at an outside so as to support the frame, wherein the shape of the dot formed at the fluorescent planes (4) has such an elliptical shape that an inner diameter of a tangent direction is increased as progressing from a center of the fluorescent planes to a periphery.

Description

Color cathode ray tube

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and in particular, an electron beam passing hole of a BM dot and a shadow mask of a phosphor surface to prevent color purity degradation caused by the electron beam striking another phosphor at the periphery of the phosphor formed on the screen side of the cathode ray tube. It is about shape.

Referring to the configuration of a general color cathode ray tube, as shown in FIG. 1, a panel 1 having a fluorescent surface 4 mounted on a front surface of a CRT and having a predetermined light emitting role on an inner side thereof is formed on a rear end of the panel 1. A funnel (2) fused to maintain the inside of the CRT in a vacuum state, a deflection yoke (5) for deflecting the electron beam (6) incident on the fluorescent surface (4) up / down / left / right, and the electron beam (6) By the magnet 10 of the 2/4/6 pole which corrects the traveling trajectory so as to strike this predetermined fluorescent surface, the frame 7 supported inside the panel 1, and the frame 7 A shadow mask 3 having a slot or dot opening formed thereon so as to pass through the electron beam 6, and the frame 7 to a stud pin 11 mounted on the inner side of the panel 1; It consists of a spring 8 for fastening.

In the figure, reference numeral 9 denotes an inner shield for shielding an external magnetic field.

In particular, when the fluorescent surface 4 is a dot type, the mask hole and the black matrix (hereinafter, referred to as “BM”) are formed in a dot shape, and the BM dot 13 in which the BM is not formed is provided with an image by emitting light. In order to reproduce, red, green, and blue (R / G / B) phosphors are respectively applied.

Looking at the operation of the conventional cathode ray tube configured as described above are as follows.

When power is applied, the electron beam 6 is emitted from an electron gun (not shown) inserted into the neck of the funnel 2, and the emitted electron beam 6 is deflected by the deflection yoke 5 to spread over the entire screen. The mask 3 is directed, about 20% of which hits the fluorescent surface 4 through the opening of the shadow mask 3 to reproduce the image.

At this time, the fluorescent surface 4 formed in the effective surface of the inner surface of the panel 1 is composed of BM and R / G / B phosphor, the purpose of the BM is the landing of the electron beam (6) by the change in tube manufacturing conditions or operating conditions (Landing) It is for improving product quality and contrast by improving color purity margin, which is a range that does not cause landing error due to position movement.

However, if the BM formed on the fluorescent surface 4 is a dot type as shown in Fig. 2, there is no problem in the case of normal landing as shown in (a), but the path of the electron beam to the deflection yoke 5 and the magnet 10 is If the deflection yoke (5) is moved forward or backward during the ICT process or the geomagnetic field of the surrounding environment is changed, the electron beam 6 does not strike the phosphor, as shown in (b) and (c). The other phosphor, that is, hitting the BM dot 13 occurs a problem that the color purity is falling, this phenomenon is more severe toward the periphery of the fluorescent surface (4). Here, the BM dot refers to a position where the BM is not formed and the phosphor is formed.

In particular, this phenomenon becomes more severe as the resolution / fine pitch (PITCH) to improve the resolution, and the countermeasure for this is to increase the pitch of the upper and lower pitches of the BM dots in the fluorescent surface, but the problem of luminance decrease Therefore, in general, a method of reducing the assembly tolerance of the deflection yoke 5, that is, bringing the color purity margin to a small level, is adopted.

However, this method also had a problem that acts as a significant cause of poor working conditions and product quality deterioration in tube manufacturing.

The present invention has been invented to solve the problems of the prior art as described above, the shape of the BM dot formed in the electron beam passing hole and the fluorescent surface of the shadow mask is the inner diameter in the tangential direction of the concentric circles toward the periphery from the center of the mask and the fluorescent surface By forming the same in each of the gradually increasing elliptical shape, the purpose is to improve the color purity margin at the periphery of the fluorescent surface without deterioration of the luminance caused by the electron beam hit another phosphor during the assembly process of the product.

1 is a cross-sectional view of a typical cathode ray tube.

FIG. 2 illustrates a landing shape of a BM dot and an electron beam at a periphery of a fluorescent surface according to the related art.

(A) is the normal landing state.

(B) is also an abnormal landing condition when the deflection yoke is retracted.

(C) also shows abnormal landing conditions when the deflection yoke is advanced.

3 is a shape diagram of an electron beam and a BM dot of the entire fluorescent surface according to the present invention;

Figure 4 is an inclination angle according to the position of the electron beam through hole and the BM dot according to the present invention.

5 is a view showing the landing shape of the BM dot and the electron beam in the periphery of the fluorescent surface according to the present invention,

(A) is the normal landing state.

(B) State diagram at the time of reverse deflection yoke.

(C) is a state diagram when the deflection yoke is advanced.

Figure 6 is a landing shape diagram of the BM dot and the electron beam in the center and the peripheral portion of the fluorescent surface according to the present invention.

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

1 panel 2 funnel

3: shadow mask 4: fluorescent surface

5: deflection yoke 6: electron beam

7: frame 8: spring

9: inner shield 10: magnet

11: stud pin 15: BM dot

16: electron beam

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

In the color cathode ray tube to which the present invention is applied, the overall configuration except for the shadow mask 3 and the fluorescent surface 4 is the same as in the prior art, and the description of the other configurations will be omitted and the same reference numerals will be given. .

In the fluorescent surface 4 according to the present invention, the BM dot 15 and the electron beam 16 in the effective surface are concentric in the tangential direction of the concentric circles toward the periphery, as shown in FIG. 3. The elliptical shape is inclined along, and this shape is due to the shape of the electron beam through hole of the shadow mask 3. That is, the shape of the BM dot 15 may be formed by elliptical shape inclined along the shape of the electron beam through hole in the periphery of the shadow mask 3 through exposure and application.

In order to form this, the shape of the used mask hole must be changed. Therefore, the shape of the electron beam passing through the shadow mask is also formed into an elliptical shape having an inclined angle as the shape of the BM dot on the fluorescent surface.

That is, the electron beam through hole short axis M _S of the shadow mask is represented by Equation 1 below, and the long axis diameter M _{L of the} electron beam through hole is represented by Equation 2 below. The short axis diameter B _S is represented by the following [Equation 3], and the long axis diameter B _L is represented by the following [Equation 4].

Equation 1 M _S = M _x × (1 + a⋅R ⁿ )

[Equation 2] M _L = M _y × (1 + b⋅R ⁿ )

Equation 3 B _S = B _x × (1 + a⋅R ⁿ )

Equation 4 B _L = B _y × (1 + b⋅R ⁿ )

Where a = -4.8E-06 to -1.2E-06, b = 1.2E-06 to 4.8E-06, n = 2, and R represents a distance from the center of the shadow mask or the fluorescent surface, M _x , M _y , B _x , B _y Are the diameters on the X and Y axes of the electron beam passing holes and the BM dots at the shadow mask and the fluorescent surface center, respectively.

As shown in FIG. 4, the inclination angle of the major axis of the electron beam passing holes of the BM dot and the mask may be represented by Equation 5 below.

The color cathode ray tube of the present invention having such a shape moves the deflection yoke 5 up / down / left / right during the work of ICT which adjusts the path of the electron beam or when the geomagnetic field of the surrounding environment changes. As shown in b), the electron beam 16 does not easily hit other BM dots 15 around.

That is, the color purity margin, which is a range in which a landing error does not occur due to the movement of the landing position of the electron beam 16 due to a change in tube manufacturing conditions or operating conditions, is improved.

In addition, the size of the BM dot 15, i.e., the luminance decrease due to the phosphor emission area, and at the same time, it is possible to prevent the phenomenon that the color purity decreases toward the high definition or the fine pitch to improve the resolution.

As described above, the present invention can improve product purity and workability by improving color purity around the fluorescent surface, that is, improving purity margin, without lowering luminance. In particular, as the wide-angle deflection is made, it is possible to exhibit an effect of improving mass productivity through securing a purity margin.

Claims (4)

A panel in which fluorescent surfaces of R, G, and B are formed on the inner side, a funnel fused to the rear end of the panel, an electron gun encapsulated in the neck portion of the funnel, and an electron beam emitted from the electron gun are used to cover the entire surface of the fluorescent surface. A deflection yoke for deflecting the electron beam so as to strike it, a frame supported inside the panel, a shadow mask supported by the frame, and a dot-shaped electron beam passing hole arranged so that the electron beam passes through the frame, and the frame In the cathode ray tube consisting of a spring mounted on the outer surface to support the The shape of the BM dot formed on the fluorescent surface is a color cathode ray tube, characterized in that to improve the color purity margin is made of an elliptical shape gradually increasing the inner diameter of the concentric circle in the tangential direction from the center of the fluorescent surface. The method of claim 1, The shape of the electron beam passing hole of the shadow mask is a color cathode ray tube, characterized in that formed in the elliptical shape of the inner diameter in the tangential direction of the concentric circle gradually increases from the center of the mask toward the periphery. The method according to claim 1 and 2, The electron beam through hole short axis M _S of the shadow mask satisfies Equation 1 below, and the long axis diameter M _L satisfies Equation 2 below. The short axis diameter B _S of the BM dot satisfies Equation 3 below, and the long axis diameter B _L satisfies Equation 4 below. Wherein a = -4.8E-06 to -1.2E-06, b = 1.2E-06 to 4.8E-06, and n = 2, wherein R represents a distance from the center of the shadow mask or the fluorescent surface Colored cathode ray tube. The method according to claim 1 or 2, The angle (θ) of the long axis of the electron beam through hole of the BM dot and the shadow mask and the vertical axis (Y) satisfies the following [Equation 5]. Equation 1 M _S = M _x × (1 + a⋅R ⁿ ) [Equation 2] M _L = M _y × (1 + b⋅R ⁿ ) Equation 3 B _S = B _x × (1 + a⋅R ⁿ ) Equation 4 B _L = B _y × (1 + b⋅R ⁿ )