JPH1186745A - Color picture tube - Google Patents

Abstract

(57) [Problem] To provide a color picture tube which does not cause deterioration of color purity by keeping a distance between a phosphor screen and a shadow mask within an allowable range even if a shadow mask undergoes thermal expansion. Aim. In a color picture tube, a shadow mask is provided.
Between the main surface portion 29 and the skirt portion 31 of the mask body 32 of 26, a bent surface portion 34 is provided which is bent from the periphery of the main surface portion to a direction approaching the center of curvature of the main surface portion.

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 deviation of beam landing due to doming of a shadow mask is suppressed.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, a color picture tube comprises a panel 2 having an effective portion 1 having a curved surface, and an envelope having a funnel 4 having a cylindrical neck 3 at one end. The panel 2 has blue, green,
A phosphor screen 5 composed of a large number of three-color phosphor layers that emit red light is provided, and a shadow mask 6 is disposed inside the phosphor screen 5 at a predetermined distance from the phosphor screen 5. On the other hand, an electron gun 8 for emitting three electron beams 7B, 7G, 7R is arranged in the neck 3 of the funnel 4. Then, the three electron beams 7B, 7G, 7R emitted from the electron gun 8 are deflected by a deflecting device (not shown) mounted outside the funnel 4 so that the shadow mask 6
The phosphor screen 5 is horizontally and vertically scanned through the device to form a structure for displaying a color image.

The above-mentioned shadow mask 6 is used for selecting the three electron beams 7B, 7G, 7R emitted from the electron gun 8 so as to correctly land the three-color phosphor layer of the phosphor screen 5. A main surface portion 10 facing the body screen 5 is formed of a curved surface, and a large number of electron beam passage holes corresponding to the trio of the three-color phosphor layer are formed in the main surface portion 10, and a skirt portion is formed around the main surface portion 10. 1
1, a mask body 12 provided with
And a mask frame 13 welded to the skirt portion 11. Then, the elastic support 14 attached to the mask frame 13 is connected to the stud pins 15 provided on the panel 2.
And is supported inside the panel 2.

In order to display an image with good color purity on the phosphor screen 5, it is necessary to dispose the shadow mask 6 in a predetermined matching relationship with the phosphor screen 5, and to obtain a color image. During operation of the tube, it must be ensured that its alignment remains unchanged.

However, the shadow mask type color picture tube reaches the phosphor screen 5 through the electron beam passage hole of the shadow mask 6 among the electron beams 7B, 7G, 7R emitted from the electron gun 8 in terms of the operation principle. The electron beams 7B, 7G, 7R are 1/3 or less of the whole, and the other electron beams 7B, 7G, 7R collide with the mask main body 12 and are heated. In this case, since the peripheral portion of the mask main body 12 is attached to the mask frame 13 which has a large heat capacity and is blackened, the heat of the peripheral portion of the mask main body 12 moves to the mask frame 13 and the mask main body 12 A temperature difference occurs between the central part and the peripheral part, and the central part is relatively heated.

When the mask body 12 is heated as described above, the mask body 12 is, as shown by a broken line in FIG. The so-called doming which bulges toward the body screen 5 is caused. As a result, the distance between the phosphor screen 5 and the shadow mask 6 exceeds the allowable range, and the electron beams 7 (7B, 7B) incident on the phosphor screen 5 through the electron beam passage holes of the shadow mask 6.
G, 7R) is a predetermined phosphor layer 17 (17B, 17G, 1).
7R) does not land properly, leading to deterioration of color purity.

In order to prevent such deterioration in color purity,
Conventionally, various measures have been taken.

As one of the methods, there is a method in which the mask body is made of a low-thermal-expansion material such as amber, and even if the mask body is heated, the resulting doming is reduced to suppress the deterioration of color purity. However, it is difficult to form such a shadow mask into a predetermined shape due to its high tensile strength, and the cost is higher than that of a low carbon steel sheet.

[0009]

As described above, the shadow mask of the color picture tube is heated by the collision of the electron beam emitted from the electron gun, and causes a doming in which the mask body swells toward the phosphor screen. . In particular, in the case of a shadow mask in which the mask body is made of a low-carbon steel sheet having a high coefficient of thermal expansion, the distance between the phosphor screen and the shadow mask changes greatly due to doming, and the phosphor passes through the electron beam passage holes of the shadow mask. The electron beam incident on the screen does not land properly on the predetermined phosphor layer, and the color purity is degraded.

In order to prevent the deterioration of the color purity, the mask body is made of a low thermal expansion material such as amber, so that even if the mask body is heated, the resulting doming is reduced and the deterioration of the color purity is suppressed. Although there is a method, there is a problem that it is difficult to form such a shadow mask into a predetermined shape due to its high tensile strength, and the cost is higher than that of a low carbon steel sheet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and maintains the distance between the phosphor screen and the shadow mask within an allowable range even if the shadow mask undergoes thermal expansion, thereby maintaining the color purity. An object of the present invention is to configure a color picture tube which does not cause deterioration.

[0012]

A shadow mask is arranged at a predetermined distance from a phosphor screen provided on an inner surface of an effective portion formed of a curved surface of a panel, and the shadow mask is arranged at a predetermined distance from the curved surface facing the phosphor screen. In a color picture tube comprising a mask body in which a large number of electron beam passage holes are formed in the main surface portion and a skirt portion is provided around the main surface portion, and a mask frame attached to the skirt portion of the mask body, Between the main surface portion and the skirt portion of the shadow mask, a bent surface portion was provided which was bent from the periphery of the main surface portion in a direction approaching the center of curvature of the main surface portion.

Further, a plurality of through holes or concave holes are formed in the bent surface portion.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color picture tube which is one embodiment of the present invention. This color picture tube has a funnel-shaped funnel 2 composed of a panel 22 having a skirt portion 21 provided around the effective portion 20 having a curved surface, and a cylindrical neck 23 having one end.
And an envelope consisting of: On the inner surface of the effective portion 20 of the panel 22, a phosphor screen 25 composed of a large number of three-color phosphor layers that emit blue, green, and red light is provided.
Further, a shadow mask 26 is arranged inside the phosphor screen 25 at a predetermined interval facing the phosphor screen 25.
On the other hand, three electron beams 2 are placed in the neck 23 of the funnel 24.
An electron gun 28 for emitting 7B, 27G, 27R is provided. Then, the three electron beams 27B, 27G, and 27R emitted from the electron gun 28 are deflected by a deflecting device (not shown) mounted outside the funnel 24, and the phosphor screen 25 is leveled through the shadow mask 26. ,
It is formed in a structure for displaying a color image by performing vertical scanning.

The shadow mask 26 has a curved main surface portion 29 facing the phosphor screen 25, and a large number of electron beam passage holes 30 are formed in the main surface portion 29 in correspondence with the trio of the three-color phosphor layer. A mask body 32 having a skirt portion 31 provided around the main surface portion 29;
A mask frame 33 is welded to the skirt portion 31 of the mask body 32. In particular, in this embodiment, a bent surface portion 34 is provided between the main surface portion 29 and the skirt portion 31 so as to be bent from the periphery of the main surface portion 29 toward the center of curvature of the main surface portion 29, A plurality of through holes 35 or recesses penetrating the plate surface are formed in the bent surface portion 34.

The through hole 35 or the concave hole of the bent portion 34
When the electron beam passage holes 30 are formed in the shadow mask material plate by the photo etching method, they are formed at the same time.
That is, when a photoresist having a pattern corresponding to the electron beam passage holes 30 is formed on both surfaces of the shadow mask material plate, the photoresist 3 on both surfaces is provided with the through holes 3.
4 or by forming a pattern corresponding to the above-mentioned recess on one surface of the shadow mask material plate, and then etching the electron beam passage hole 30 at the same time. You.

The shadow mask 26 includes an elastic support 36 attached to a mask frame 33 and a panel 2.
The second skirt portion 21 is supported inside the panel 22 by engaging with a stud pin 37 provided on the skirt portion 21.

As described above, the main surface portion 29 of the mask body 32
When a bent surface portion 34 is provided between the skirt portion 31 and a plurality of through-holes 35 or concave holes are formed in the bent surface portion 34, the mask main body 32 forms the electron beams 27B, 27G, and 27.
Even if it is heated by the collision of R 2 and thermal expansion occurs, the distance between the phosphor screen 25 and the shadow mask 26 is maintained within an allowable range, and the electron beams 27B,
It is possible to reduce the landing deviation between 27G and 27R and to provide a color picture tube which does not cause deterioration in color purity.

That is, of the electron beams 27B, 27G, and 27R generally emitted from the electron gun 28, the electron beams 27B, 27G, and 27R that reach the phosphor screen 25 through the electron beam passage holes 30 of the shadow mask 26.
Is less than 1/3 of the whole, and the other electron beams 27
B, 27G and 27R collide with the mask body 32. The mask body 32 is heated and thermally expanded by this collision. In this case, if a bent surface portion 34 bent in a direction approaching the center of curvature is provided on the outer periphery of the main surface portion 29 of the mask body 32, FIG. As shown in FIG.
The doming of the mask main body 32 is suppressed by standing in the direction. Further, when a plurality of through holes or concave holes are formed in the bent surface portion 34, the thermal conductivity of the bent surface portion 34 decreases,
Heat hardly moves from the peripheral portion of the mask body 32 to the mask frame 33, and the entire main surface portion 29 is uniformly heated.

As a result, as shown by the broken line, the doming of the mask main body 32 is suppressed, and the distance between the phosphor screen 25 and the shadow mask 26 is kept within an allowable range, and the three-color phosphor layers 40 (40B, 40G, 40G, 40R) can be kept small.

[0022]

As described above, when a bent surface portion is provided between the main surface portion of the mask body of the shadow mask and the skirt portion, and a plurality of through holes or concave holes are formed in the bent surface portion, Even if the mask body thermally expands due to the collision of the electron beam, the color picture tube which does not deteriorate the color purity can be provided by keeping the distance between the phosphor screen and the shadow mask within an allowable range.

[Brief description of the drawings]

FIG. 1A is a diagram showing an overall configuration of a color picture tube according to an embodiment of the present invention, and FIG. 1B is a diagram showing a configuration of a main part thereof.

FIG. 2 is a diagram for explaining thermal expansion of a shadow mask due to collision of an electron beam with the color picture tube.

FIG. 3 is a diagram showing a configuration of a conventional color picture tube.

FIG. 4 is a diagram for explaining thermal expansion of a shadow mask due to collision of an electron beam of the conventional color picture tube.

[Explanation of symbols]

 Reference Signs List 20 effective portion 22 panel 25 phosphor screen 26 shadow mask 29 main surface portion 30 electron beam passage hole 31 skirt portion 33 mask frame 34 bent surface portion 35 through hole

Claims (2)

[Claims] 1. A shadow mask is arranged at a predetermined distance from a phosphor screen provided on an inner surface of an effective portion formed of a curved surface of a panel, and the shadow mask is a main surface portion having a curved surface facing the phosphor screen. A color picture tube comprising: a mask main body having a plurality of electron beam passage holes formed therein and a skirt provided around the main surface; and a mask frame attached to the skirt of the mask main body. Characterized in that a bent surface portion is provided between the main surface portion and the skirt portion so as to be bent in a direction approaching the center of curvature of the main surface portion from the periphery of the main surface portion. 2. A color picture tube according to claim 1, wherein a plurality of through holes or concave holes are formed in the bent surface portion.