JPH06310049A - Color picture tube - Google Patents

Abstract

PURPOSE:To easily form a phosphor screen, and to prevent absence of an electron beam by making the horizontal diameter of an electron beam passing hole wider as the horizontal end part is closer and smaller as the vertical end part is closer. CONSTITUTION:The electron beam passing hole 20 of a shadow mask is opened wide in a phosphor screen side, and is formed into longitudinal rearly rectangular shape having a minimum diameter part for determining the hole diameter on the inside closer to the surface in the side of an electron gun. A plurality of the rectangular electron beam passing holes 20 are formed in line through a bridge 21 vertically in the direction of Y, while a plurality of holes are provided horizontally in the direction X at a predetermined pitch. The horizontal diameter D of the minimum diameter part 22 of the electron beam passing hole 20 is larger as the hole is closer to the horizontal end part from the vertical axis or Y axis passing the center of the shadow mask, and is smaller as the hole is closer to the vertical end part from the horizontal axis or X axis passing the center of the shadow mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to a color picture tube in which an electron beam passage hole of a shadow mask has a substantially rectangular shape.

[0002]

2. Description of the Related Art Generally, a color picture tube is provided with a large number of electron beam passage holes which face a phosphor screen formed of a three-color phosphor layer which emits blue, green and red lights formed on the inner surface of a panel and are spaced apart from each other by a predetermined distance. A shadow mask having is arranged. Then, the three electron beams emitted from the electron gun are deflected by the magnetic field generated by the deflection yoke, and the phosphor screen is horizontally and vertically scanned through the shadow mask to form a structure for displaying a color image. . The shadow mask has a selection function of allowing the three electron beams to correctly enter the three-color phosphor layer.

In such a color picture tube, as shown in FIG. 5, in the phosphor screen, black stripes 1 which are long in the vertical direction are formed in parallel at a predetermined pitch in the horizontal direction and embedded between the black stripes 1. An in-line type color picture tube having a structure in which three-color phosphor layers 2B, 2G, and 2R are formed in the electron gun, and the electron gun is an electron gun that emits three electron beams arranged in a row passing on the same horizontal plane is widely used.

In this color picture tube, as shown in FIG. 6, the electron beam passage hole 4 of the shadow mask has a large opening on the phosphor screen side, and the hole diameter is set to the inner side near the opposite side to the electron gun side. It is formed in a vertically long substantially rectangular shape having a minimum diameter portion 5 to be determined. The electron beam passage holes 4 are arranged in a straight line in the vertical direction (Y direction) via the bridge portion 6, and the vertical arrangement is formed in a plurality of rows arranged in the horizontal direction (X direction). Has been done.

The horizontal hole diameter D of the minimum diameter portion 5 of the electron beam passage hole 4 and the horizontal arrangement pitch PH are such that the arrangement pitch PH becomes closer to the peripheral portion where the horizontal deflection angle of the electron beam increases. Since the landing margin with respect to the three-color phosphor layer is reduced, the electron beam can be made large so as not to land on the other-color phosphor layers to form a black stripe having a large width dimension. Regarding the horizontal hole diameter D of the minimum diameter portion 5, the beam spot is increased toward the peripheral portion so that the landing of the electron beam with respect to the phosphor layer is deviated so that a portion which does not emit light (lack of electron beam) cannot be formed. Making it big.

That is, the hole size of the minimum diameter portion 5 of the electron beam passage hole 4 of the shadow mask of the above-mentioned in-line type color picture tube is the stripe shape in which the three-color phosphor layer is long in the vertical direction. There is no need to consider the horizontal direction, when forming a phosphor screen by a photo printing method using a shadow mask as an exposure mask,
And, as a countermeasure against the landing of the electron beam on the three-color phosphor layer, especially the lack of the electron beam, the horizontal hole diameter D of the minimum diameter portion 5 may be taken into consideration. This horizontal hole diameter D is expressed by a function of X. It

However, even if the shadow mask is constructed as described above, the horizontal hole diameter DAPP of the minimum diameter portion 5 of the electron beam passage hole 4 of the shadow mask as seen from the deflection center of the color picture tube is not equal to the curvature of the inner surface of the panel. When the curvature of the shadow mask changes depending on the angle, the angle θmH formed by the electron beam 8 and the shadow mask 9 at the horizontal axis end and the angle θmD formed by the electron beam 8 and the shadow mask 9 at the diagonal axis end are Is θmD> θmH. Therefore, the hole diameter DAPP in the horizontal direction of the minimum diameter portion of the electron beam passage hole is smaller at the horizontal axis end than at the diagonal axis end, which is required for the formation of the required phosphor screen and prevention of electron beam chipping as described above. Produces the opposite result.

[0008]

As described above, the electron beam passage hole of the shadow mask of the in-line type color picture tube is formed in a vertically long substantially rectangular shape, and the electron beam passage hole has a bridge portion in the vertical direction. A plurality of them are arranged in a straight line through this, and the arrangement in the vertical direction is formed in a structure in which a plurality of rows are arranged in the horizontal direction. Regarding the horizontal hole diameter D and the horizontal arrangement pitch PH of the minimum diameter portion of the electron beam passage hole, with respect to the arrangement pitch PH, the three-color phosphor becomes closer to the peripheral portion where the horizontal deflection angle of the electron beam becomes larger. Since the landing margin with respect to the layer becomes small, the electron beam can be made large so as not to land on the phosphor layer of another color to form a black stripe having a large width dimension. Regarding the horizontal hole diameter D of the minimum diameter portion, the beam spot is increased toward the peripheral portion so that the landing of the electron beam with respect to the phosphor layer is deviated, that is, the electron beam is not chipped. Making it big.

However, even if the shadow mask is constructed as described above, the hole diameter DAP in the horizontal direction of the minimum diameter portion of the electron beam passage hole of the shadow mask viewed from the deflection center of the color picture tube.
When the curvature of the shadow mask changes according to the curvature of the inner surface of the panel, P is the angle θmH between the electron beam and the shadow mask at the horizontal axis end, and the angle between the electron beam and the shadow mask at the diagonal axis end. Since the formed angle θmD is such that θmD> θmH, the horizontal hole diameter DAPP of the minimum diameter portion of the electron beam passage hole becomes smaller at the horizontal axis end than at the diagonal axis end, and the required phosphor screen It has the opposite effect on formation and electron beam chipping prevention.

The present invention has been made in view of the above problems, and facilitates formation of a phosphor screen through an electron beam passage hole of a shadow mask of an in-line type color picture tube and prevention of chipping of the electron beam. The purpose is to make it the required size.

[0011]

A shadow mask having a large number of electron beam passage holes is arranged at a predetermined distance from a phosphor screen, and the electron beam passage holes of the shadow mask are formed in a substantially rectangular shape and in a horizontal direction. In a color picture tube arranged at a predetermined pitch, the horizontal hole diameter of the electron beam passage hole is larger from the vertical axis passing through the center of the shadow mask toward the horizontal end, and is horizontal passing through the center of the shadow mask. The smaller the distance from the axis to the end in the vertical direction, the smaller.

[0012]

As described above, the hole diameter in the horizontal direction of the electron beam passage hole of the shadow mask is larger as it is closer to the horizontal end from the vertical axis passing through the center of the shadow mask, and is vertical from the horizontal axis passing through the center of the shadow mask. By making the diameter smaller toward the end in the direction, the hole diameter in the horizontal direction of the electron beam passage hole seen from the deflection center can be made larger at the horizontal axis end than at the diagonal axis end of the shadow mask. Therefore, it is possible to facilitate the formation of the phosphor screen and prevent the electron beam from being chipped around the phosphor screen.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 2 shows a color picture tube which is an embodiment of the present invention. This color picture tube has an envelope composed of a panel 10 whose inner surface is a curved surface having a predetermined curvature and a funnel 11 integrally joined to the panel 10. The inner surface of the panel 10 has a vertically elongated black stripe. Are arranged in parallel in the horizontal direction at a predetermined pitch, and a phosphor screen 12 in which stripe-shaped three-color phosphor layers emitting blue, green, and red are formed between the black stripes is provided. A shadow mask 14 having a large number of electron beam passage holes, which will be described later, formed of a curved surface 13 corresponding to the curvature of the inner surface of the panel 10 is arranged facing the phosphor screen 12 and separated by a predetermined distance. On the other hand, in the neck 15 of the funnel 11, an electron gun 17 that emits the three electron beams 16 arranged in a row passing through the same horizontal plane is arranged. The three electron beam 16 emitted from the electron gun 17 is funneled.
The fluorescent screen 12 is deflected by a magnetic field generated by a deflection yoke 18 mounted on the outside of the mirror 11, and the phosphor screen 12 is horizontally and vertically scanned through the shadow mask 14 to form a color image display structure.

The electron beam passage hole of the shadow mask 14 is formed in a vertically long substantially rectangular shape having a large opening on the side of the phosphor screen 12 and having a minimum diameter portion for determining the hole diameter on the inner side close to the surface on the side of the electron gun 17. As shown in FIG. 1, as shown in FIG. 1, a plurality of substantially rectangular electron beam passage holes 20 are linearly arranged in the vertical direction (Y direction) via the bridge 21. Are arranged in a plurality of columns in the horizontal direction (X direction) at a predetermined pitch. In addition, the horizontal hole diameter D of the minimum diameter portion 22 of the electron beam passage hole 20 increases from the vertical axis (Y axis) passing through the center of the shadow mask to the horizontal end, and the horizontal axis passing through the center of the shadow mask. The smaller the distance from the (X axis) toward the end in the vertical direction, the smaller the size.

Now, considering an arbitrary point A on the shadow mask 14 shown in FIG. 3, the point A is the central axis of the shadow mask 14, that is, the tube axis (Z axis) (see FIG. 2) and the tube axis. Function A of the distance from the horizontal and vertical axes orthogonal to the point O
It is represented by (x, y, z). Here, the angle formed by the line OA connecting the point O and the point A with the vertical axis is θf, and the distance from the point O to the point A is Rf. As shown in FIG. Is Δz, the point A can be given by those functions A (Rf, θf, Δz).

Therefore, when the angle between the electron beam 16 deflected at the deflection center DC and incident on the point A and the shadow mask 14, that is, the incident angle of the electron beam 16 on the shadow mask 14 at the point A is θ m, the electrons are The horizontal component θmx of the incident angle θm of the beam 16 is expressed by Equation ₁ where L _{0 is} the distance from the deflection center DC to the inner surface of the panel 10 and q ₀ is the distance between the panel 10 and the shadow mask 13 at the center of the panel 10. Is

[Equation 1] The hole diameter DAPP in the horizontal direction of the minimum diameter portion of the electron beam passage hole at the point A viewed from the deflection center DC is given by

[0018]

[Equation 2] That is, the hole diameter DAPP in the horizontal direction of the minimum diameter portion of the electron beam passage hole viewed from the deflection center DC is set to increase as the distance from the vertical axis increases.

In general, when the horizontal distance x from the center O of the shadow mask 14 is kept constant and the absolute value | y | of the vertical distance y is increased, the number 3 increases and the number 4 increases.
Decreases.

[0020]

[Equation 3]

[Equation 4] However, since the increase of the equation 3 exceeds the decrease of the equation 4, θmx increases when x is kept constant and | y | is increased.
That is, the horizontal hole diameter DAPP of the minimum diameter portion of the electron beam passage hole viewed from the deflection center DC increases as the distance from the horizontal axis increases when x is constant.

In this case, of the hole diameter DAPP at the horizontal axis end and the hole diameter DAPP at the diagonal axis end, the hole diameter DAPP at the diagonal axis end is larger. Therefore, the electron beam may land on the phosphor layer of another color at the end of the diagonal axis of the phosphor screen, or the electron beam may be chipped at the end of the horizontal axis. Also, when the phosphor screen is formed, the width of the black stripe at the end of the horizontal axis becomes smaller than the end of the diagonal axis of the phosphor screen, and the amount of light when forming the black stripe by the photo printing method using the shadow mask as the exposure mask. Adjustment tends to be difficult with the correction filter.

Therefore, the horizontal hole diameter D of the minimum diameter portion of the electron beam passage hole 20 of the shadow mask 14 is changed not only in the horizontal direction but also in the vertical direction, and the maximum diameter of the electron beam passage hole seen from the deflection center DC is obtained. The hole diameter DAPP in the horizontal direction of the small diameter part increases with increasing distance from the vertical axis (closer to the horizontal end), and decreases or equals with increasing distance from the horizontal axis (closer to the vertical end). By doing so, it is possible to prevent the landing of the other-color phosphor layer of the electron beam at the diagonal axis end portion of the phosphor screen, and to prevent the electron beam chipping at the horizontal axis end portion. Further, it becomes possible to easily form a required phosphor screen.

[0023]

The hole diameter in the horizontal direction of the substantially rectangular electron beam passage hole of the shadow mask is larger from the vertical axis passing through the center of the shadow mask toward the horizontal end, and from the horizontal axis passing through the center of the shadow mask. By making it smaller toward the vertical end, the horizontal hole diameter of the electron beam passage hole seen from the deflection center can be made larger at the horizontal axis end than at the diagonal axis end of the shadow mask. It is possible to prevent landing of the other-color phosphor layer of the electron beam at the end of the diagonal axis, and to prevent chipping of the electron beam at the end of the horizontal axis of the phosphor screen. Further, the phosphor screen can be easily formed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the structure of a shadow mask according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a color picture tube which is an embodiment of the present invention.

FIG. 3 is a diagram for explaining a horizontal hole diameter of an electron beam passage hole of the shadow mask.

FIG. 4 is a view for explaining the horizontal hole diameter of the electron beam passage hole of the shadow mask.

FIG. 5 is a diagram showing a configuration of a phosphor screen having a black stripe.

6 (a) is a plan view showing an arrangement of electron beam passage holes of a conventional shadow mask, and FIG. 6 (b) is its BB line.
Sectional drawing, FIG.6 (c) is CC sectional drawing.

[Explanation of symbols]

 10 ... Panel 12 ... Phosphor screen 13 ... Curved surface 14 ... Shadow mask 16 ... 3 Electron beam 17 ... Electron gun 18 ... Deflection yoke 20 ... Electron beam passage hole 21 ... Bridge 22 ... Minimum diameter part

Claims (1)

[Claims] 1. A shadow mask having a large number of electron beam passage holes is arranged at a predetermined distance from a phosphor screen, and the electron beam passage holes of the shadow mask are formed in a substantially rectangular shape and horizontally at a predetermined pitch. In the arranged color picture tube, the electron beam passage hole is larger in the horizontal hole diameter from the vertical axis passing through the center of the shadow mask to the horizontal end, and from the horizontal axis passing through the center of the shadow mask. A color picture tube characterized by being smaller as it gets closer to the vertical end.