JPH11354042A - Color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease deterioration of image quality due to the light emission of a phosphor caused by part of an electron beam irregularly reflected by a mask frame by means of forming long recessed grooves inside the mask frame in the lengthwise direction of its sidwall part by protruding the sidewall part of the mask frame in the directon of a skirt section of a panel. SOLUTION: When a phosphor screen is scanned more than its effective size and when recessed grooves 29 are formed in a sidewall part 23 of a mask frame, the excess scanned electron beam 16 hits against the inside surface of the sidewall part 23. The excess scanned electron beam 16 hit against the recessed grooves 29 repeats the hits and reflection, and thereafter, part of it is allowed to reach a phosphor screen through an electron beam passing hole 20 of a shadow mask 22, so that the reflected beam quantity reaching the phosphor screen can be reduced. Thus, undesired light emission of the phosphor layer due to the reflected beam is reduced, and the deterioration of image quality such as color purity degradation is decreased. The image deterioration of high luminance image is prevented by applying it to a super-large tube or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type color picture tube, and more particularly, to a color picture tube capable of reducing deterioration of color purity due to irregular reflection of an electron beam on a mask frame on which a shadow mask is mounted.

[0002]

2. Description of the Related Art In general, in a shadow mask type color picture tube, a shadow mask structure is arranged so as to face a phosphor screen formed of a three-color phosphor layer provided on an inner surface of a panel. The three electron beams emitted are selected, and the phosphor screen is scanned so that a color image is displayed. As shown in FIG. 5, the shadow mask structure includes a shadow mask 3 provided with a large number of electron beam passage holes on an effective surface opposed to a phosphor screen 2 provided on the inner surface of the panel 1; A mask frame 5 having a substantially L-shaped cross section having a side wall 4 to which a peripheral portion is attached. The shadow mask structure 6 includes an elastic support 7 attached to the side wall 4 of the mask frame 5.
The stud pins 9 provided on the skirt 8 of the panel 1
To be supported inside the panel 1.

[0003] In recent years, such color picture tubes have become large-sized,
Construct phosphor screen 2 with higher definition
The arrangement pitch of the color phosphor layers is small, and accordingly, the arrangement pitch of the electron beam passage holes of the shadow mask 3 is small, and the landing margin of the electron beam with respect to the three color phosphor layers is small. Therefore, in order to display an image without color shift on the phosphor screen 2 in such a color picture tube, it is necessary to make the beam landing on the three-color phosphor layer more accurate than in a normal color picture tube. . For this purpose, it is necessary to keep the positional relationship between the panel 1 and the shadow mask structure 6, particularly the distance (q value) between the inner surface of the panel 1 and the effective surface of the shadow mask 3, within a predetermined allowable range.

However, the shadow mask structure 6 generally has
The phosphor screen 2 is formed of a thin metal plate such as a cold-rolled steel plate, and passes through an electron beam passage hole on an effective surface thereof.
Is less than 1/3 of the amount of the electron beam emitted from the electron gun, and most of the electron beam collides with the shadow mask 3. Due to this collision, the shadow mask 3 is heated and thermally expanded, and in the shadow mask 3 having a curved surface whose central portion of the effective surface protrudes in the direction of the phosphor screen 2, the shadow mask 3 undergoes doming which swells in the direction of the phosphor screen 2. If the bulging amount due to the doming exceeds the allowable range of the q value, the beam landing on the three-color phosphor layer is shifted, and a color shift occurs. The color shift due to the thermal expansion of the shadow mask 3 varies depending on the beam current amount of the electron beam, the size of the image pattern, the duration of the image pattern, and the like.

As a means for reducing the landing deviation due to the thermal expansion of the shadow mask 3, a method of improving the heat radiation property by blackening or forming a black coating on the shadow mask, suppressing the temperature rise of the shadow mask, and using an amber shadow mask There has been proposed a method of suppressing thermal expansion by forming the material with a low thermal expansion material.

However, even if the above arrangement can reduce the deviation of the beam landing relative to the three-color phosphor layer, the problem that arises when the phosphor screen is scanned beyond the effective size, that is, the mask frame has a problem. The electron beam collides with the inner surface of the side wall and is irregularly reflected, and a part of the reflected beam passes through the electron beam passage hole of the shadow mask and undesirably emits a phosphor layer that should not emit light. The problem of deterioration of image quality such as deterioration of purity cannot be solved.

[0007]

As described above, in the conventional color picture tube, when the phosphor screen is scanned beyond the effective size, the electron beam collides with the inner surface of the side wall portion of the mask frame and is irregularly reflected. There is a problem that a part of the beam passes through the electron beam passage hole of the shadow mask and causes the phosphor layer that should not emit light to emit light, thereby deteriorating image quality such as deterioration of color purity.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a color image receiving apparatus capable of reducing a decrease in image quality caused by a part of an electron beam irregularly reflected by a mask frame causing a phosphor layer to emit light. The purpose is to construct a tube.

[0009]

Means for Solving the Problems (1) There is provided a shadow mask structure opposed to a phosphor screen formed on an inner surface of a panel provided with a skirt portion in a peripheral portion, and the shadow mask structure is provided with a phosphor screen. In a color picture tube comprising a shadow mask having a large number of electron beam passage holes formed on opposing surfaces and a mask frame having a side wall to which a peripheral portion of the shadow mask is attached, a panel skirt is provided on a side wall of the mask frame. The groove protruded in the direction of the side wall, and a long groove was formed inside the mask frame in the length direction of the side wall portion.

(2) In the color picture tube of (1),
A plurality of concave grooves were formed in parallel.

(3) In the color picture tube of (2),
A plurality of rows of concave grooves were formed with the same depth and the same width.

(4) In the color picture tube according to any one of (1) to (3), an elastic support for supporting the shadow mask is mounted on the side wall, and a groove is formed to avoid the mounting portion of the elastic support. Formed.

(5) In the color picture tube of (4),
The concave groove was formed substantially all around the mask frame, avoiding the mounting portion of the elastic support.

(6) In the color picture tube of (1),
The peripheral portion of the shadow mask is attached to one end of the side wall portion on the phosphor screen side, and an inner protrusion is provided on the other end side of the side wall portion. Electrons emitted from the electron gun without being shielded by the inner protrusion. A concave groove was formed at the portion where the beam collided.

[0015]

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

FIG. 3 shows a color picture tube which is one embodiment of the present invention. This color picture tube has an envelope composed of a substantially rectangular panel 11 provided with a skirt portion 10 on the periphery and a funnel 12 in a funnel shape. On the inner surface of the panel 11, a phosphor screen 13 composed of a three-color phosphor layer that emits blue, green, and red light is provided. A substantially rectangular shadow mask structure 14 is arranged inside the phosphor screen 13 so as to face the phosphor screen 13. Meanwhile, funnel 1
3 electron beams 16B, 16G, 16
An electron gun 17 for emitting R is provided. The three electron beams 16B, 16B emitted from the electron gun 17 are
G, 16R are deflected by a deflecting device 18 mounted on the outside of the funnel 12, and the phosphor screen 13 is horizontally and vertically scanned through the shadow mask structure 14, thereby forming a structure for displaying a color image. ing.

As shown in FIG. 1, the shadow mask structure 14 is provided with a large number of electron beam passage holes 20, and a skirt portion is formed by bending a skirt portion around the effective surface 21 facing the phosphor screen. A substantially rectangular shadow mask 22 and an inner protruding portion 24 (FIG. 3) are formed at one end of a side wall portion 23 to which a skirt portion of the shadow mask 22 is attached.
) Provided with a substantially rectangular mask frame 25 having a substantially L-shaped cross section. The shadow mask 22 and the mask frame 25 are arranged such that the skirt portion of the shadow mask 22 is located inside the side wall portion 23 of the mask frame 25.
The other end is welded.

The shadow mask structure 14 is
The elastic support 26 attached to the side wall 23 of the mask frame 25, in the illustrated example, at each corner thereof, is attached to the panel 1.
By locking the stud pins 27 provided on the skirt portion 11 of the panel 10, the shadow mask 22 is opposed to the phosphor screen 13, and the overhang portion 23 of the mask frame 25 is set to the electron gun 17 side so that the inside of the panel 10 (See FIG. 3).

In this embodiment, as shown in FIG. 2, the side wall 23 of the mask frame 25 protrudes in a mountain shape in the direction of the skirt portion of the panel. A plurality of concave grooves 29 having the same depth and the same width, which are long in the vertical direction, are formed in a plurality of rows in substantially the entire periphery of the side wall portion 23 avoiding the mounting portion of the elastic support.

When the concave groove 29 is provided in the side wall portion 23 of the mask frame 25 as described above, as shown in FIG. 4, when the phosphor screen 13 is scanned beyond the effective size, the overscanned electron beam 16 (16B , 16G, 16R) collide with the inner surface of the side wall portion 23. The electron beam 16 colliding with the concave groove 29 repeats collision and reflection, and a part of the electron beam 16 passes through the electron beam passage hole 20 of the shadow mask 22. As a result, the light reaches the phosphor screen, and the amount of reflected beams reaching the phosphor screen can be reduced. Moreover, the energy of the reflected beam reaching the phosphor screen is attenuated by repeated collision and reflection.

Accordingly, by providing the concave groove 29 in the side wall 23 of the mask frame 25 as described above, it is possible to reduce unwanted light emission of the phosphor layer due to the reflected beam from the side wall 23, and to deteriorate color purity. In addition, it is possible to reduce the deterioration of the image quality, and it is possible to effectively prevent the deterioration of the image quality when a high-luminance image is displayed, particularly when applied to a super-large tube.

Moreover, since the concave groove 29 is provided so as to avoid the mounting portion of the elastic support 26 for supporting the shadow mask structure 14, the reflection from the side wall 23 can be performed without lowering the mounting strength of the elastic support 26. Beams can be reduced.

In the above embodiment, a plurality of grooves are provided in parallel in the length direction of the side wall of the mask frame.
The same effect can be obtained by forming only one row of the concave grooves in the length direction of the side wall portion.

Further, in the above embodiment, the side wall of the mask frame is projected in the shape of a mountain in the direction of the skirt of the panel, and a concave groove having a shape corresponding to the projection of the mountain is formed inside the mask frame. The shape of this groove is arc-shaped,
Other shapes such as a rectangular shape may be used.

[0025]

According to the present invention, a fluorescent screen is formed by protruding in the direction of the skirt of the panel on the side wall of the mask frame of the shadow mask structure and forming a long groove in the length of the side wall on the inside of the mask frame. When scanning beyond the effective size, the electron beam repeatedly strikes and reflects on the inner surface of the side wall, reducing the amount of reflected beam reaching the phosphor screen and attenuating its energy, deteriorating the color purity and degrading image quality. The deterioration can be reduced, and in particular, when a high-brightness image is displayed by applying to a super-large tube or the like, it is possible to effectively prevent deterioration of image quality.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a shadow mask structure of a color picture tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a side wall portion of a mask frame of the shadow mask structure.

FIG. 3 is a diagram showing a configuration of a color picture tube according to an embodiment of the present invention.

FIG. 4 is a view for explaining collision and reflection of an electron beam on a side wall of the mask frame.

FIG. 5 is a view for explaining a configuration of a conventional shadow mask structure of a color picture tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Skirt part 11 ... Panel 13 ... Phosphor screen 14 ... Shadow mask structure 20 ... Electron beam passage hole 22 ... Shadow mask 23 ... Side wall part 24 ... Inner overhang part 25 ... Mask frame 29 ... Groove

Claims (6)

[Claims] 1. A shadow mask structure formed on an inner surface of a panel provided with a skirt portion on a peripheral portion thereof, the shadow mask structure facing a phosphor screen. In a color picture tube comprising a shadow mask provided with an electron beam passage hole and a mask frame having a side wall to which a peripheral portion of the shadow mask is attached, the color picture tube protrudes toward the skirt portion of the panel on the side wall of the mask frame. A color picture tube characterized in that a long groove is formed in the length of the side wall portion inside the mask frame by the protrusion. 2. The color picture tube according to claim 1, wherein a plurality of grooves are formed in parallel. 3. The color picture tube according to claim 2, wherein a plurality of rows of concave grooves are formed with the same depth and the same width. 4. An apparatus according to claim 1, wherein an elastic support for supporting the shadow mask is mounted on the side wall, and a concave groove is formed so as to avoid a portion where the elastic support is mounted. A color picture tube as described in Crab. 5. The color picture tube according to claim 4, wherein the concave groove is formed on substantially the entire circumference of the mask frame avoiding the mounting portion of the elastic support. 6. A peripheral portion of the shadow mask is attached to an end portion of the side wall portion on the side of the phosphor screen, and an inner protruding portion is provided at an end opposite to the side wall portion so that electrons are not shielded by the inner protruding portion. 2. The color picture tube according to claim 1, wherein a concave groove is formed in a portion where the electron beam emitted from the gun collides.