JP2001118525A - Color cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a color cathode-ray tube which does not cause lowering of color purity or workability of a shadow mask assembling, by controlling distortion of a sidewall portion, occurred in the vicinity of an opposite angle portion of a mask frame molded by press working. SOLUTION: A color cathode-ray tube has an almost rectangular mask body with mounted skirt portion around effective surface, and a shadow mask of an almost rectangular mask frame, in which an internal stretch portion 27 is mounted on one end portion of a sidewall portion and the skirt portion of the mask body welding to the internal surface of the sidewall portion, at least one projecting portion 31 of a height which is projected outwardly and does not reach the other end portion is formed in the other side of each sidewall portion of the mask frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and more particularly to a color cathode ray tube which suppresses the influence of distortion caused by drawing during press forming of a substantially rectangular mask frame of a shadow mask.

[0002]

2. Description of the Related Art In general, a color cathode ray tube has a substantially rectangular shadow mask disposed opposite a phosphor screen formed of a three-color phosphor layer provided on the inner surface of a substantially rectangular panel, and has a funnel neck. A three-electron beam emitted from the electron gun provided in the above is deflected by a deflection yoke, and this electron beam is selected by a shadow mask and made incident on the three-color phosphor layer to form a structure for displaying a color image. Have been.

Generally, in the shadow mask, as shown in FIG. 7, a large number of electron beam passage holes 2 for selecting three electron beams are formed in an effective surface 1 facing a phosphor screen. A substantially rectangular mask body 4 having a skirt 3 bent therefrom, and an inwardly extending portion 6 provided substantially at a right angle on one end side of the side wall portion 5, and the inner or outer side surface of the side wall portion 5 has the above-mentioned structure. The mask body 7 has a substantially rectangular mask frame 7 to which the skirt 3 is welded.

Conventionally, in such a shadow mask, both the mask body 4 and the mask frame 7 are formed from a cold-rolled steel plate. However, the shadow mask is heated by the collision of a high-density electron beam for displaying a high-intensity image, and is locally formed. In order to suppress the deterioration of color purity caused by the thermal expansion of the mask main body 4, only the mask main body 4 is formed of a low thermal expansion material such as amber,
A shadow mask to which a mask frame 7 made of a cold-rolled steel plate is attached has been put to practical use. Conventionally, this shadow mask is welded to the inner surface of the side wall 5 with the skirt 3 of the mask body 4 inside the side wall 5 of the mask frame 7.

As described above, in the shadow mask in which the low thermal expansion mask body 4 is mounted on the inner surface of the side wall 5 of the high thermal expansion mask frame 7, the inner diameter of the mask frame 7 is much larger than the outer diameter of the mask body 4. When the shadow mask is heated in the manufacturing process of the color cathode ray tube, the mask frame 7 having a high thermal expansion is locally plastically deformed to pull the mask body 4 having a low thermal expansion, thereby deteriorating the color purity. When the color cathode ray tube is operated for a long time, the heat of the mask body 4 heated by the collision of the electron beam is transmitted to the mask frame 7, and the mask body 4 is stretched and deformed by the thermally expanded mask frame 7, and the color is changed. Causes deterioration of purity.
If the difference between the inner diameter of the mask frame 7 and the outer diameter of the mask body 4 is small, it is not easy to insert the skirt 3 of the mask body 4 inside the side wall 5 of the mask frame 7 and the workability is reduced. .

That is, in the shadow mask in which the low thermal expansion mask body 4 is attached to the inner surface of the side wall 5 of the high thermal expansion mask frame 7, the distance between the skirt 3 of the mask body 4 and the side wall 5 of the mask frame 7. It is important that

[0007] However, since the mask frame 7 is generally formed by press molding, a large aperture is applied particularly in the vicinity of a diagonal portion of the substantially rectangular mask frame 7. As a result, the excess thickness generated by the drawing process escapes in the direction of the long and short side wall portions 5 sandwiching the diagonal portion, and as shown in FIG. As shown in FIG. 10, a curved or inclined deformation occurs, or a wavy deformation occurs as shown in FIG. When the side wall portion 5 is deformed in this manner, the distance between the skirt portion 3 of the mask body 4 and the side wall portion 5 of the mask frame 7 deviates from an appropriate value, and the above-described deterioration in color purity and workability in assembling the shadow mask are reduced. Mimic

As a technique for preventing the deformation of the side wall portion,
JP-A-63-250039, JP-A-10-792
No. 33, JP-A-11-45664, etc.
By providing a protruding portion protruding inside the mask frame on the side wall portion, it is easy to insert the mask body inside the mask frame, and by welding the protruding portion to the skirt portion of the mask body, the mask body thermally expanded. The figure shows that the mask body is prevented from being deformed due to being pulled by the mask frame and the strength of the mask frame itself is increased. However, in such a shadow mask, when a high-luminance image is displayed, the influence of the thermal expansion of the mask frame on the mask body is different between the projecting portion in contact with the skirt portion of the mask body and the portion not in contact with the skirt portion. Thus, there is a difference in the deterioration of the color purity, and the deterioration of the color purity over the entire screen is not uniform. Therefore, when such a shadow mask is used, it is very difficult to correct color purity deterioration.

Further, in order to reduce the resonance frequency of a shadow mask, US Pat. No. 14,645,968 discloses a method of reducing the resonance frequency of a shadow mask by using the center of each side wall between welding points between a substantially rectangular mask body and a mask frame. In the figure, a portion provided with a protrusion at a portion and a diagonal portion is shown. However, in such a shadow mask, since the skirt portion other than the welding point of the mask body with the mask frame is separated from the mask frame, it becomes easier to vibrate, and the deterioration of the color purity over the entire screen becomes uneven. There is a problem.

[0010]

As described above, in the shadow mask in which the low thermal expansion mask main body is attached to the inner side surface of the high thermal expansion mask frame side wall, the skirt portion of the mask main body and the side wall portion of the mask frame are provided. It is important to make the distance between them appropriate. However, in general, since the mask frame is formed by press molding, a large aperture is added near the diagonal portion, and a side wall portion that should be perpendicular to the inner overhang portion is curved or inclined due to the escape of the excess thickness, or a wave is formed. A hitting deformation occurs. For this reason, the distance between the skirt portion of the mask body and the side wall portion of the mask frame deviates from the appropriate value, resulting in deterioration of color purity and reduction in workability of assembling the shadow mask.

As a technique for preventing the deformation of the side wall portion,
It has been proposed to provide a protrusion protruding inside the mask frame on the side wall to improve the insertability of the mask body into the mask frame, and to weld the protrusion to the skirt of the mask body. However, in such a shadow mask, when a high-luminance image is displayed, the influence of the thermal expansion of the mask frame on the mask main body is different between the projecting portion in contact with the skirt portion of the mask main body and the portion not in contact with the skirt portion. Thus, there is a difference in the deterioration of the color purity, and the deterioration of the color purity over the entire screen is not uniform. Therefore, it becomes very difficult to correct the color purity deterioration.

Further, in order to reduce the resonance frequency of the shadow mask, it has been proposed to provide projections at the center and diagonal of each side wall between welding points between the substantially rectangular mask body and the mask frame. Have been. However, in such a shadow mask, since the skirt portion other than the welding point of the mask body with the mask frame is separated from the mask frame, it becomes easier to vibrate, and the deterioration of the color purity over the entire screen becomes uneven. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made to prevent deformation of a side wall portion caused by escape of excess thickness of a stop near a diagonal portion of a mask frame formed by press molding, and to prevent color deformation. It is an object of the present invention to provide a color cathode ray tube which does not deteriorate the purity or lower the workability of assembling a shadow mask.

[0014]

A plurality of electron beam passage holes are formed in an effective surface provided on an inner surface of a panel facing a phosphor screen, and a skirt portion is provided around the effective surface. A cathode mask having a substantially rectangular mask frame provided with a mask main body and an inwardly extending portion provided on one end side of the side wall portion and a skirt portion of the mask main body welded to the inner side surface of the side wall portion. In the tube, at least one convex portion protruding outward and not reaching the one end was formed on the other end of each side wall of the mask frame.

In the above color cathode ray tube, when the height of the convex portion is hc and the height of the skirt portion of the mask body is hm, hc <hm.

[0016]

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

FIG. 1 shows a color cathode ray tube which is one embodiment of the present invention. This color cathode ray tube has a substantially rectangular panel 10.
And a funnel-shaped envelope. On the inner surface of the panel 10, a phosphor screen 12 made of a three-color phosphor layer that emits blue, green, and red light is provided.
A substantially rectangular shadow mask 13 is arranged inside the phosphor screen 12 so as to face the phosphor screen 12, and an elastic support 14 attached to a mask frame, which will be described later, is connected to a stud pin 15 provided on the panel 10. It is supported by stopping. On the other hand, the neck 1 of the funnel 11
An electron gun 19 that emits three electron beams 18B, 18G, and 18R is provided in the apparatus. And the electron gun 19
The three electron beams 18B, 18G, and 18R emitted from the mirror are deflected by a deflection yoke 20 mounted outside the funnel 11, and the phosphor screen 12 is horizontally and vertically scanned through a shadow mask 13, thereby forming a color image. It is formed in a structure for displaying.

The shadow mask 13 has an effective surface 22 formed of a curved surface facing the phosphor screen 12 and has a large number of electron beam passage holes formed thereon, and a skirt portion 24 is provided around the effective surface 22. A substantially rectangular mask body 25 is formed, and an inner protruding portion 27 is provided at one end of the side wall portion 26 and an outer protruding portion 28 inclined at the other end is provided. The skirt portion 24 of the mask main body 25 is welded to a side surface of the mask main body 25, and is formed of a substantially rectangular mask frame 29 made of a cold-rolled steel plate.

In particular, in this embodiment, as shown in FIG. 2, at least one protruding portion 31 protruding outward is provided on each of the other end portions of the side wall portions 26 on the long and short sides of the mask frame 29. ing. This projection 30 is formed as shown in FIG.
As shown in the figure, the height is hc, the height of the side wall 26 of the mask frame 29 (the height from the other end to the one end) is hs, and the height of the skirt 24 of the mask body 25 is hs. Is hm, hc <hs and hc <hm.

In the example of a 19-inch color cathode ray tube, two such convex portions 30 are provided on the short side wall portion and four on the long side wall portion as shown in FIG. Formed, each having a width of 20 mm, a height of 10 mm, and a protrusion length of d
It is formed in a size of 0.5 mm (see FIG. 3B).

In the shadow mask, the mask body and the mask frame are formed by press molding, respectively, and then the mask body is inserted into the inside of the side wall of the mask frame. Assembled by welding to the side. In particular, the mask body is formed by pressing a flat mask with electron beam holes formed by photo-etching in advance to a curved surface by press forming to form an effective surface, and then forming a skirt by drawing. Is done. When formed by such press working, as shown in FIG. 4, the mask body 25 made of a high-tensile invar material can be formed by springback even if the skirt 24 is bent at a right angle to the effective surface 22. The free end side of 24 opens outward. Therefore, the maximum dimension of the mask body 25 before assembly of the shadow mask, that is, the dimension between the free ends of the skirt portion 24 is Lm, the inner diameter dimension of the mask frame 29 is Lw, and the maximum outer diameter dimension of the mask frame 29, that is, the other end is Assuming that the edge outer diameter is Lr, Lw <Lm <Lr.

Therefore, when the mask body 25 is inserted into the inside of the side wall 26 of the mask frame 29 and welded, as shown in FIG. 5, the mask body 25 is welded to the side wall 26 in a state of being ΔLp compressed. In this case, if the projection 30 is provided on the side wall 26 of the mask frame 29 as described above, the undesired deformation of the side wall 26 due to the press-drawing process is absorbed, and the skirt 24 of the mask main body 25 is substantially removed. The entire circumference can be in close contact with the inner side surface of the side wall portion 26 of the mask frame 29, and it is possible to prevent the deterioration of the color purity and the reduction in workability of assembling the shadow mask caused by the deformation of the side wall portion 26 of the conventional mask frame 29.

That is, when the mask frame is formed by press molding, a large aperture is applied near the diagonal portion, so that the excess thickness escapes in the direction of the long and short side wall portions. In the conventional mask frame, as shown in FIGS. As described above, the side wall portion is deformed to be curved, inclined, or wavy. However, if the convex portion 31 is provided on the side wall portion as in this embodiment, the excess thickness is absorbed, and the side wall portion is deformed. Deformation can be prevented. The absorption of the surplus varies depending on the size (width × height × projection length) and the number of the protrusions 31. Therefore, by adjusting these sizes and numbers, the deformation can be effectively prevented from being applied to all of the mask frames.

On the other hand, as shown in FIG. 6A, when the skirt portion 24 of the mask body 25 is pulled in the direction of the arrow, it is plastically deformed at a certain point as shown by a dashed line, and cannot return to the original state. . At this point, the amount of pulling of the skirt portion 24 is ΔLm1, the amount of thermal expansion of the mask body 25 due to heating is ΔLm2 as shown in (b), and the amount of heat expansion of the mask frame 29 due to heating as shown in (c). Assuming that the expansion amount is ΔLr, the mask body 25 is deformed when ΔLr> ΔLm1 + ΔLm2.

On the other hand, when assembling the shadow mask 13 as described above, the skirt 2
4 is inserted into the side wall 26 of the mask frame 29 in a state of being compressed by ΔLp and welded, the mask frame 2
9, even if the thermal expansion amount ΔLr exceeds ΔLm1 + ΔLm2, the skirt portion 24 of the mask body 25 expands by the compression amount ΔLp, so that ΔLr does not exceed ΔLm1 + ΔLm2.
The deformation of the mask body 25 can be prevented.

Further, the outer edge dimension Lr of the other end of the mask frame 29 is larger than the dimension Lm between the free ends of the skirt portion 24 of the mask body 25, and Lm <Lr, and the other end of the mask frame 29 is inclined. Since the outer protruding portion is formed, the mask main body 25 can be easily inserted into the inside of the mask frame 29, and the shadow mask can be easily assembled.

Further, when a high-luminance image is displayed, even if the mask frame 29 thermally expands, the skirt 2
Since almost the entire circumference of 4 is in contact with the side wall 26 of the mask frame 29, local deterioration of color purity can be prevented. In addition, deterioration of color purity due to resonance can be reduced.

In the above embodiment, the shadow mask whose mask body is made of a low thermal expansion material has been described. However, in the present invention, both the mask body and the mask frame are made of a material having a high thermal expansion such as a cold-rolled steel plate. Also applicable to shadow masks.

[0029]

As described above, when a protrusion having a height that protrudes outward and does not reach one end at the other end of the side wall of the mask frame is formed, the mask frame can be formed by press working. Prevents deformation of the side wall due to the excess thickness of the diaphragm near the diagonal part of the mask escaping in the direction of the long and short side walls. Degradation and workability of assembling the shadow mask can be prevented. In addition, deterioration of color purity due to resonance can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a mask frame of the color cathode ray tube.

FIGS. 3A and 3B are diagrams for explaining the size of a convex portion of the mask frame. FIG.

FIGS. 4 (a) and 4 (b) are diagrams showing the relationship between the dimensions of the mask main body and the mask frame of the color cathode ray tube.

FIG. 5 is a diagram showing a main configuration for explaining a relationship between a mask body and a mask frame of the color cathode ray tube.

6A is a view for explaining plastic deformation of the mask body, FIG. 6B is a view for explaining thermal expansion of the mask body, and FIG. It is a figure for explaining expansion.

FIG. 7A is a perspective view showing a configuration of a conventional shadow mask, and FIG. 7B is a sectional view thereof.

FIG. 8A is a perspective view showing a configuration of a conventional mask frame, and FIG. 8B is a cross-sectional view thereof.

FIG. 9 is a view showing a modification of a conventional mask frame.

FIG. 10 is a diagram showing a different modification of the conventional mask frame.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Panel 12 ... Phosphor screen 13 ... Shadow mask 22 ... Effective surface 24 ... Skirt part 25 ... Mask main body 26 ... Side wall part 27 ... Inside overhang part 29 ... Mask frame 31 ... Convex part

Claims (2)

[Claims] 1. A substantially rectangular mask body having a plurality of electron beam passage holes formed in an effective surface provided on an inner surface of a panel facing a phosphor screen, and a skirt portion provided around the effective surface. An inner projection is provided on one end side of the side wall portion, and a color cathode ray tube having a shadow mask comprising a substantially rectangular mask frame to which an inner surface of the side wall portion is welded with a skirt portion of the mask body, A color cathode ray tube, wherein at least one projection protruding outward and not reaching the one end is formed at the other end of each side wall of the mask frame. 2. The color cathode ray tube according to claim 1, wherein hc is smaller than hm, where hc is the height of the convex portion and hm is the height of the skirt portion of the mask body.