JPH11250823A - Color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color picture tube by disposing reinforcing beads at an effective surface of a shadow mask so as to prevent deterioration of color purity even if curve holding strength is enhanced. SOLUTION: A plurality of projecting or recessed reinforcing beads 36 having the short axis of a shadow mask oriented in a longitudinal direction are provided at an effective surface 32 of a mask body 33 facing a phosphor screen. The width of each of the reinforcing beads 36 is narrowed from the center of the mask body 33 toward the peripheral portion in the direction of the long axis of the shadow mask. It is desirable that the reinforcing bead 36 should be formed in a length of 50% or more of the interval between long sides of the effective surface of the mask body 33 astride the long axis 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 the strength of holding a curved surface of a shadow mask is increased to suppress the deterioration of color purity due to doming.

[0002]

2. Description of the Related Art In general, as shown in FIG. 5, a color picture tube has a substantially rectangular panel 3 having a skirt portion 2 provided around a curved effective portion 1 and a funnel-shaped funnel 4 as shown in FIG. And an envelope consisting of: On the inner surface of the effective portion 1 of the panel 3, a phosphor screen 5 including a black light absorbing layer and a three-color phosphor layer provided so as to be embedded in the gap between the black light absorbing layers is provided. I have. A substantially rectangular shadow mask 6 is arranged inside the phosphor screen 5 so as to face the phosphor screen 5. The shadow mask 6 has an effective surface 7 facing the phosphor screen 5.
A substantially rectangular mask body 8 provided with a large number of electron beam passage holes, and a substantially rectangular mask frame 9 attached to the periphery of the mask body 8.
On the other hand, three electron beams 12
An electron gun 13 for emitting B, 12G, 12R (only 12G is shown) is provided. The three electron beams 12B, 12G, and 12R emitted from the electron gun 13 are deflected by a deflecting device 14 mounted outside the funnel 4, and the three electron beams 12B, 12G, and 12R are sorted by the shadow mask 6. The phosphor screen 5 is horizontally and vertically scanned to display a color image.

At present, as shown in FIG. 6, such a color picture tube has a plurality of electron beam passage holes 16 in a vertical axis (short axis: Y axis) direction on an effective surface 7 of a mask body of a shadow mask. Are arranged in a row via a bridge 17, and a plurality of electron beam passage holes formed of a plurality of electron beam passage holes 16 in the short axis direction are arranged in a plurality of rows in the horizontal axis (long axis: X axis) direction. Corresponding to the arrangement of the electron beam passage holes 16 of the shadow mask, the phosphor screen 5 is provided so as to be embedded in the gap between the striped light absorbing layer elongated in the short axis direction and the light absorbing layer. A black-striped color picture tube composed of a striped three-color phosphor layer has been widely put to practical use.

In such a color picture tube, in order to display an image without color shift on the phosphor screen 5, the three electron beams 12B, 12G and 12R passing through the electron beam passage holes 16 of the shadow mask 6 are used. , Each 3
It is necessary to correctly land on the color phosphor layer. For this purpose, it is important to maintain the positional relationship between the panel 3 and the shadow mask 6, particularly the distance (q value) between the inner surface of the effective portion 1 of the panel 3 and the effective surface 7 of the mask body 8 within a predetermined allowable range. .

In recent years, in a color picture tube, an effective portion of a panel has been flattened in order to improve visibility. In view of the visibility and the molding of the panel, it is necessary to reduce the curvature of the inner surface of the effective portion of the panel as compared with the inner surface of the effective portion of the conventional color picture tube in order to cope with the flattening of the outer surface. Corresponding to the curvature of the inner surface, the curvature of the effective surface of the mask body needs to be significantly reduced. Therefore, in a color picture tube in which the effective portion of the panel is flattened, the curved surface holding strength of the effective surface of the shadow mask is deteriorated. Therefore, it is necessary to improve the curved surface holding strength.

In this case, the shadow mask of the black stripe type color picture tube has a strip-shaped non-porous portion in which no electron beam passage hole is formed in the short axis direction due to the arrangement of the electron beam passage holes, but the long axis. Since there is no such band-shaped non-porous portion in the direction, it is possible to effectively improve the curved surface holding strength of the effective surface by making the curvature in the short axis direction larger than in the long axis direction.

For this reason, in the color picture tube in which the effective portion of the panel is flattened, the inner surface of the effective portion of the panel is a curved surface having a curvature in the short axis direction, and the effective surface corresponding to the shape of the inner surface of the effective portion. There is a shadow mask in which the curvature in the minor axis direction of the surface is increased. Such a shadow mask is more effective when applied to a wide tube having an aspect ratio of 16: 9. In addition, as the curved shape of the effective surface, the radius of curvature in the long axis direction near the center of the inner surface of the effective portion of the panel is almost infinite, and the radius of curvature in the long axis direction near the peripheral portion in the long axis direction is the long axis curvature near the center. The radius of curvature is almost constant smaller than the radius, and in the short axis direction, the radius of curvature in the short axis direction near the peripheral portion in the short axis direction is smaller than the radius of curvature in the short axis direction near the center. As shown in FIG. 7, there is a shadow mask in which the effective surface 7 of the shadow mask has a similar curved surface.

Generally, in a shadow mask type color picture tube, an electron beam reaching a phosphor screen through an electron beam passage hole of the shadow mask is less than 1/3 of the total electron beam emitted from the electron gun. Yes, the other electron beams collide with the shadow mask and are converted into thermal energy to heat the shadow mask. as a result,
The shadow mask thermally expands and causes doming in which the effective surface swells toward the phosphor screen. If the distance between the inner surface of the effective portion of the panel and the effective surface of the shadow mask exceeds an allowable range due to the doming, the beam landing on the phosphor layer shifts, and the color purity deteriorates. The magnitude of the deviation in beam landing due to the thermal expansion of the shadow mask varies greatly depending on the brightness of the image pattern, the duration of the pattern, and the like. In particular, when locally displaying a high-luminance pattern, local doming occurs, and local beam landing deviation occurs within a short time.
This local deviation of the beam landing tends to appear in the elliptical region 19 on the phosphor screen 5 which is separated from the short axis by about 1/3 of the short side interval, as shown in FIG.

The local beam landing deviation due to the local doming increases as the curvature of the effective surface of the shadow mask decreases, and is a problem that cannot be avoided in flattening the effective portion of the panel. is there.

As a countermeasure for preventing deterioration of color purity caused by local deviation of beam landing due to local doming, JP-A-7-161306 discloses a method in which a reinforcing bead is provided on an effective surface of a shadow mask and a curved surface is provided. It has been shown to improve holding strength.

Although this reinforcing bead is effective in preventing the color purity from deteriorating due to local doming, on the other hand, it deforms the electron beam passage hole during the molding of the mask body, and the inner surface of the effective portion of the panel and the shadow mask. When a phosphor screen is formed by a photographic printing method using a shadow mask as a photomask to change the distance from the effective surface, the position and shape of the black light absorbing layer and the three-color phosphor layer are easily changed. The change in the position and shape of the black light absorbing layer and the three-color phosphor layer is because the light from the exposure light source obliquely crosses the electron beam passage holes near the effective surface of the shadow mask when forming the phosphor screen. It is more likely to occur near the phosphor screen.

The positions of the black light absorbing layer and the three-color phosphor layer,
In order to prevent the shape from changing, the height of the reinforcing bead is reduced to suppress the deformation of the electron beam passage hole during molding, and to change the distance between the inner surface of the effective part of the panel and the effective surface of the shadow mask. Although it is sufficient to reduce the height, if the height of the reinforcing bead is reduced, the effect of improving the curved surface holding strength decreases, and the shadow mask in which the curvature of the effective surface decreases with the flattening of the effective portion of the panel can be used practically. Curved surface holding strength cannot be obtained.

[0013]

As described above, in a color picture tube in which the effective portion of the panel is flattened in order to improve the visibility, the curvature of the inner surface of the effective portion is reduced, and the curvature of the inner surface of the effective portion is reduced. Accordingly, it is necessary to reduce the curvature of the effective surface of the mask body. Therefore, the curved surface holding strength of the effective surface decreases. Therefore, it is necessary to improve the curved surface holding strength.

In this case, the shadow mask of the black stripe type color picture tube has a plurality of electron beam passage holes arranged in a row in the short axis direction, and a plurality of electron beam passage holes in the short axis direction in the long axis direction. There is a band-shaped non-porous portion where the electron beam passage holes are not formed in the short axis direction, but there is no such band-shaped non-porous portion in the long axis direction.
Increasing the curvature in the short axis direction rather than the long axis direction can effectively improve the curved surface holding strength of the effective surface.

Accordingly, the shadow mask in which the curvature of the effective surface in the short axis direction is increased corresponding to the inner surface of the effective portion of the panel having the curvature in the short axis direction, or the inner surface shape of the effective portion of the panel corresponding to the effective surface. The radius of curvature in the major axis direction near the center of the effective surface is substantially infinite, the radius of curvature in the major axis direction near the peripheral portion in the major axis direction is a substantially constant radius of curvature smaller than the radius of curvature in the major axis direction near the center, In the minor axis direction, there is a shadow mask in which the minor axis radius of curvature near the center is smaller than the minor axis radius of curvature near the minor axis peripheral part.

On the other hand, in order to prevent color misregistration due to local beam landing deviation due to local doming of the effective surface of the shadow mask, a reinforcing bead is provided on the effective surface to improve the curved surface holding strength. There is a shadow mask.

However, when a reinforcing bead is provided on the effective surface of the shadow mask, the hole for deforming the electron beam is deformed and the distance between the inner surface of the effective portion of the panel and the effective surface of the shadow mask is changed when the mask body is formed. When a phosphor screen is formed by a photographic printing method using a shadow mask as a photomask, the position and shape of the black light absorbing layer and the three-color phosphor layer are easily changed. In order to prevent the position and shape of the black light absorbing layer and the three-color phosphor layer from changing, the height of the reinforcing bead is reduced to suppress deformation of the electron beam passage hole at the time of forming the mask body, and to reduce The distance between the inner surface of the effective part and the effective surface of the shadow mask may be reduced, but if the height of the reinforcing bead is reduced, the effect of improving the curved surface holding strength is reduced and the curvature of the effective surface is reduced. The mask has a problem that a practically usable curved surface holding strength cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and a color picture tube which does not deteriorate color purity even if a reinforcing bead is provided on an effective surface of a shadow mask to increase a curved surface holding strength. It is intended to constitute.

[0019]

(1) A substantially rectangular shadow mask is disposed so as to face a phosphor screen provided on an inner surface of an effective portion of a substantially rectangular panel. A substantially rectangular mask body provided with a large number of electron beam passage holes on an effective surface opposed to the phosphor screen, and a substantially rectangular mask frame attached to a peripheral portion of the mask body. In a color picture tube, a plurality of convex or concave reinforcing beads whose longitudinal direction is the short axis direction of the shadow mask are provided on the effective surface of the mask main body, and the width of these reinforcing beads is set to be equal to the length of the shadow mask from the center of the mask main body. It became narrower toward the periphery in the axial direction.

(2) The outer surface of the effective portion has a substantially rectangular panel having a flat surface or a curved surface close to a flat surface, and is substantially opposed to the phosphor screen provided on the inner surface of the effective portion of the panel. A rectangular shadow mask is placed on the
A substantially rectangular mask body having a large number of electron beam passage holes in an effective surface of the shadow mask facing the phosphor screen; and a substantially rectangular mask attached to a periphery of the mask body. In a color picture tube composed of a frame, a plurality of convex or concave reinforcing beads whose longitudinal direction is the short axis direction of the shadow mask are provided on the effective surface of the mask body, and the width of these reinforcing beads is increased from the center of the mask body. It became narrower toward the periphery in the axial direction.

(3) In the color picture tube according to (1) or (2), the height of the wide reinforcing bead on the center side of the mask main body or the height of the narrow reinforcing bead on the peripheral side with respect to the height or depth of the reinforcing bead. Lower in depth or depth.

(4) In the color picture tube of (1) or (2), the reinforcing bead is formed so as to extend over the long axis of the shadow mask so as to have a length of 50% or more of the long side interval of the effective surface of the mask body.

[0023]

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. The color picture tube has an envelope composed of a substantially rectangular flat panel 22 having a skirt portion 21 provided around the effective portion 20 and a funnel 23 having a funnel shape. On the inner surface of the effective portion 20 of the panel 22, a striped black light absorbing layer elongated in the short axis (Y axis) direction;
There is provided a phosphor screen 24 including a striped three-color phosphor layer provided so as to be embedded in the striped gap of the black light absorbing layer. Further, a substantially rectangular shadow mask 25 is arranged inside the phosphor screen 24 so as to face the phosphor screen 24. On the other hand, the three electron beams 27B, 2
Electron gun 28 emitting 7G, 27R (only 27G is shown)
Are arranged. Then, the three electron beams 27B, 27G, and 27R emitted from the electron gun 28 are deflected by a deflecting device 30 mounted outside the funnel 23, and the three electron beams 27B, 27G, and 27R are sorted by the shadow mask 25. Then, the phosphor screen 24 is horizontally and vertically scanned to form a structure for displaying a color image.

The flattened panel 22 has an effective portion 2
The outer surface of 0 is a flat surface or a curved surface having a slight curvature, the inner surface has a radius of curvature in the long axis direction near the center is almost infinite, and the radius of curvature in the long axis direction near the peripheral portion in the long axis direction is the long axis near the center. The radius of curvature is almost constant, which is smaller than the radius of curvature in the direction. In the minor axis direction, the radius of curvature in the minor axis direction is constant, or the radius of curvature in the minor axis direction near the minor axis direction is smaller than the radius of curvature in the minor axis direction near the center. It is formed on a curved surface with a reduced radius.

On the other hand, the shadow mask 25 has a substantially rectangular mask body 33 having a large number of electron beam passage holes formed in an effective surface 32 facing the phosphor screen 24.
And a substantially rectangular mask frame 34 attached to the periphery of the mask body 33.
The effective surface 32 facing the phosphor screen 24 is formed into a curved surface corresponding to the inner surface shape of the effective portion 20 of the panel 22.

Further, in this embodiment, FIG.
As shown in FIG. 7, the effective surface 32 has a concave shape having a semicircular cross-sectional groove protruding in the opposite direction (electron gun side) of the phosphor screen with the short axis (Y axis) direction of the shadow mask as the longitudinal direction. A plurality of reinforcing beads 36 are provided in parallel with the short axis and symmetrically with respect to the short axis. Each reinforcing bead 36 is formed so as to extend over the long axis (X axis) to have a length of 50% or more of the long side interval of the effective surface 32, has a wide width at the center of the effective surface 32, and has a peripheral portion in the long axis direction. , The width becomes narrower and deeper sequentially or stepwise.

For example, in an example of a color picture tube shadow mask having an aspect ratio of 16: 9 and a diagonal dimension of 76 cm, as shown in FIG.
5mm from both long sides of the effective surface across the long axis
It is provided on the inner side and has a width of 25 mm, 15 mm, 10 mm, 10 mm, and 8 mm in the short side direction from the center of the effective surface.

As described above, the length is at least 50% of the long side interval parallel to the short axis of the effective surface 32 of the shadow mask 25, and the width becomes narrower and the depth becomes lower toward the long axis direction peripheral portion. By providing the concave reinforcing bead 36, the strength of holding the curved surface of the shadow mask can be increased, and deterioration of color purity due to local doming can be suppressed. Moreover, reinforcing beads 3
Even when the mask body 33 is provided, the stripe-shaped black light-absorbing layer caused by the deformation of the electron beam passage hole during the molding of the mask body 33 and the change in the distance between the inner surface of the effective portion 20 of the panel 22 and the effective surface 32 of the shadow mask 25 are changed. The change in the position and the shape of the three-color phosphor layer can be reduced, and the deterioration of the quality of the phosphor screen 24 can be prevented.

That is, when the reinforcing bead 36 having a concave groove having a semicircular cross section is provided, a portion which greatly contributes to the improvement of the curved surface holding strength is particularly the reinforcing bead 3 having a large plastic deformation.
6 is considered to be the side edge. In addition, the strength between the side edges of the reinforcing bead 36 depends on the curvature between the side edges if the depth of the reinforcing bead 36 is the same, and the reinforcing bead 36 having a narrower width than the wide reinforcing bead 36 has. Contributes significantly to the improvement of the curved surface holding strength.

On the other hand, when the reinforcing bead 36 is provided, the position and shape of the black light absorbing layer and the three-color phosphor layer change depending on the incident angle of the electron beam passing through the electron beam passage hole in the portion where the reinforcing bead 36 is formed. Closely related.

That is, FIG.
6a, as shown by overlapping the narrow reinforcing beads as 36b, the electron beam passing holes 38 on the short axis side of the shadow mask 25 among the electron beam passing holes 38 at the portions where the reinforcing beads 36a and 36b are formed. Means that the electron beam is 2
As shown by 7a, 27b and 27c, the light enters at a relatively large angle θ. Therefore, these electron beams 27a,
The apparent electron beam passage holes 3 for 27b and 27c
8 except for the deformation during the molding of the mask body,
This is almost the same as the case without the reinforcing beads 36a and 36b. However, since the electron beam enters the electron beam passage hole 38 on the opposite side of the short axis at a relatively small angle θ as shown by 27d and 27e, the electron beam 27d
, 27e, the apparent opening area of the electron beam passage hole 38 is reduced, and the effect appears outside the black light absorbing layer and the three-color phosphor layer. In addition, this effect is greater at the electron beam passage holes 38 at the peripheral portion in the long axis direction where the electron beam having a large horizontal deflection angle crosses.

Accordingly, by making the width and height of the reinforcing bead 36 at the peripheral portion in the long axis direction crossed by the electron beam having a large deflection angle of the horizontal deflection smaller than the width and height of the reinforcing bead 36 at the central portion. Of the black light absorbing layer and the three-color phosphor layer in the peripheral portion in the long-axis direction, which is caused by crossing obliquely more obliquely, can be reduced.

On the other hand, when forming the mask main body by press molding and simultaneously forming the reinforcing beads 36, the depth of the formable reinforcing beads 36 has a correlation with the width thereof, and the curved surface holding strength of the shadow mask 25 is determined. If the rising of the reinforcing bead 36 is made abrupt in order to increase the deformation, the deformation of the electron beam passage hole at that portion becomes large, and in some cases, the electron beam passage hole is crushed.

Because of this, the shadow mask 25
The effective bead 32 is provided with a reinforcing bead 36 whose width becomes narrower and becomes shallower from the central part toward the peripheral part in the longitudinal direction with the short axis direction as the longitudinal direction. The deep reinforcing bead 36 can effectively reinforce the central portion of the effective surface 32 of the shadow mask 25 having a low curved surface holding strength while suppressing the quality of the central portion of the phosphor screen 24 to a negligible degree. With respect to the portion, the reinforcing bead 36 having a small width and a small depth can similarly suppress the quality of the peripheral portion of the phosphor screen 24 to a negligible level and improve the curved surface holding strength of the peripheral portion.

Therefore, by configuring the shadow mask 25 as described above, as the effective portion 20 of the panel 22 is flattened, the effective surface 32 of the shadow mask 25 is
Even if is flattened, local doming caused by local heating due to electron beam collision can be suppressed, and a color picture tube in which color purity does not easily deteriorate can be configured.

In the above embodiment, a concave reinforcing bead having a semicircular cross section protruding in the opposite direction of the phosphor screen is provided on the effective surface of the shadow mask. Instead of a circular shape, as shown in FIG. 4A, another shape such as a reinforcing bead 36 having a square cross section may be used.

As shown in FIGS. 3B and 3C, the reinforcing beads 3 have a semicircular or rectangular cross section.
6 may be projected in the direction of the phosphor screen to form a convex reinforcing bead 36.

[0039]

As described above, when the reinforcing bead is provided on the effective surface of the shadow mask, the strength of holding the curved surface of the shadow mask can be increased, the deterioration of color purity due to local doming can be suppressed, and the reinforcing bead can be provided. However, the position of the striped black light absorbing layer or the three-color phosphor layer caused by the deformation of the electron beam passage hole during the molding of the mask body and the change in the distance between the inner surface of the effective portion of the panel and the effective surface of the shadow mask. In addition, a change in shape can be reduced, and deterioration of the quality of the phosphor screen can be prevented.

[Brief description of the drawings]

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

FIG. 2A is a plan view showing a configuration of a mask body of the shadow mask, and FIG. 2B is a sectional view thereof.

FIG. 3 is a view for explaining an operation of a reinforcing bead provided on an effective surface of the mask body.

FIGS. 4A to 4C are diagrams for explaining shapes of reinforcing beads different from the reinforcing beads.

FIG. 5 is a diagram showing a configuration of a conventional color picture tube.

FIG. 6 is a view showing an arrangement of electron beam passage holes in a shadow mask of a conventional color picture tube.

FIG. 7 is a diagram showing a curved shape of an effective surface of a conventional flattened shadow mask.

FIG. 8 is a diagram illustrating positions where beam landing deviation is likely to occur due to local doming of the shadow mask.

[Explanation of symbols]

 Reference Signs List 20 effective part 22 panel 24 phosphor screen 25 shadow mask 32 effective surface 33 mask body 34 mask frame 36 reinforcing bead

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masayo Inoue 1-9-2 Hara-cho, Fukaya-shi, Saitama Prefecture Toshiba Fukaya Electronics Factory Co., Ltd.

Claims (4)

[Claims] 1. A substantially rectangular shadow mask is disposed opposite a phosphor screen provided on an inner surface of an effective portion of a substantially rectangular panel, and the shadow mask faces the phosphor screen. In a color picture tube comprising a substantially rectangular mask body provided with a large number of electron beam passage holes on an effective surface thereof, and a substantially rectangular mask frame attached to a peripheral portion of the mask body, A plurality of convex or concave reinforcing beads whose longitudinal direction is the minor axis direction of the shadow mask are provided on the effective surface of the mask body, and the width of these reinforcing beads is set such that the width of the reinforcing beads extends from the center of the mask body to the major axis direction of the shadow mask. A color picture tube characterized by becoming narrower toward the periphery. 2. An effective portion has a substantially rectangular panel whose outer surface is a flat surface or a curved surface close to a flat surface, and is substantially opposed to a phosphor screen provided on an inner surface of the effective portion of the panel. A rectangular shadow mask is disposed, and the shadow mask is formed on a substantially rectangular mask body having a large number of electron beam passage holes formed on an effective surface facing the phosphor screen, and on a peripheral portion of the mask body. A color picture tube comprising an attached substantially rectangular mask frame, wherein a plurality of convex or concave reinforcing beads having a longitudinal direction in a short axis direction of the shadow mask are provided on an effective surface of the mask body. A color picture tube, wherein the width of these reinforcing beads becomes narrower from the center of the mask body toward the peripheral portion in the longitudinal direction. 3. The height or depth of a narrow reinforcing bead on the peripheral portion side is lower than the height or depth of a wide reinforcing bead on the center side of the mask body. Item 3. A color picture tube according to item 1 or 2. 4. The collar according to claim 1, wherein the reinforcing bead extends over the long axis of the shadow mask and has a length of 50% or more of a long side interval of the effective surface of the mask body. Picture tube.