JPH07161306A - Color image receiving tube - Google Patents

Abstract

PURPOSE:To prevent the deterioration in an appearance of a fluorescent screen and an image quality by setting the height of a reinforcing bead at the predetermined height or less. CONSTITUTION:In a color image receiving tube provided with a shadow mask 20 consisting of a mask main body 26 facing a fluorescent screen 3, in which an effective face in which multiple electron beam passing holes are formed in the predetermine arrangement is formed on the inside face of a panel 1, at the preset interval and a mask frame 27 mounted in the circumference part of the mask main body 26, a reinforcing bead 28 is formed in the whole side crossing the horizontal direction of the effective face of the shadow mask 20. The height of the reinforcing bead 28 is gradually lowered from the central part of the effective face to the boundary part between an ineffective face and a skirt part, and the height of the reinforcing bead 28 in the boundary part between the effective face and the ineffective part is set to be as two thirds as the height of the reinforcing bead 28 in the central part of the effective face or less.

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 having a reinforcing bead formed on its effective surface for improving the mechanical strength of a shadow mask.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 10, a color picture tube has an envelope composed of a substantially rectangular spherical panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1. Formed on the inner surface of the panel 1 is a phosphor screen 3 composed of dot-shaped or stripe-shaped three-color phosphor layers that emit blue, green, and red. The phosphor screen 3 faces the phosphor screen 3 and has a rectangular shape inside thereof. The shadow mask 4 is arranged. The shadow mask 4 is formed into a spherical surface having a predetermined curvature and has a large number of electron beam passage holes formed in a predetermined arrangement. A skirt is formed,
A rectangular mask body 7 whose effective surface 5 faces the phosphor screen 3 and a skirt portion 6 of the mask body 7.
And a mask frame 8 attached to the mask frame 8. The frame holder 9 attached to the mask frame 8 is supported on the inside of the panel 1 by engaging with a stud pin 10 provided on the panel 1. On the other hand, in the neck 11 of the funnel 2, three electron beams 12B, 12G, 1
An electron gun 13 that emits 2R is arranged.

The shadow mask 4 is used to sort the three electron beams 12B, 12G, and 12R emitted from the electron gun 13 so that the three electron beams 12B, 12G, and 12R are correctly incident on the three-color phosphor layers. The deflected three electron beams 12B, 12G, 12R are deflected by the magnetic field generated by the deflection yoke 14 mounted on the outer side of the funnel 2, and the deflected electron beams 12B, 12G, 12R are selected by the shadow mask 4 to cause fluorescence. Horizontal body screen 3,
The structure is such that a color image is displayed by performing vertical scanning.

In such a color picture tube, a color picture tube whose screen surface is flattened recently has been put into practical use, and this color picture tube has an effective surface of the shadow mask 4 as the screen surface is flattened. Is also flattened. Therefore, swelling (doming) of the effective surface 5 in the direction of the phosphor screen 3 caused by thermal expansion due to collision of the electron beams 12B, 12G, and 12R is large, and three electron beams 12B are applied to the phosphor layers of three colors. , 12G, 12R landing deviation is large, and the screen quality is likely to deteriorate.

As a means for suppressing the doming of the shadow mask 4, as shown in FIG. 11, a strip-shaped reinforcing bead 16 protruding toward the phosphor screen side is formed on the effective surface 5 so that the mechanical strength of the mask body 7 is increased. It has been proposed (Japanese Patent Laid-Open No. 5-258679). As shown in FIG. 12A, the reinforcing bead 16 has a constant height on the effective surface 5, is gradually lowered from the periphery of the effective surface 5 and surrounds the effective surface 5. And skirt 18
It is formed so that the height becomes 0 at the boundary portion 19 between the effective surface 5 and the boundary portion 19 between the non-effective surface 17 and the skirt portion 18 as shown in FIG. 12B. It has a certain height.

Therefore, when a color picture tube is constructed by using the shadow mask 4 having such reinforcing beads 16 formed, there is a problem that the appearance of the phosphor screen and the quality of the image drawn on the phosphor screen are deteriorated. is there.

That is, in general, a phosphor screen of a color picture tube is formed by a photo printing method using a shadow mask 4 incorporated in the tube as a photo mask and light emitted from a light source arranged at a position corresponding to an electron gun. It is formed by printing a pattern of electron beam passage holes of the shadow mask 4 on a screen forming member layer such as a phosphor slurry layer formed on the inner surface of the. Therefore, in the shadow mask 4 on which the reinforcing beads 16 are formed as described above, there is a large difference in height between the effective surface 5 and the reinforcing beads 16 at the peripheral edge of the effective surface 5, so that fluorescent light is generated in the peripheral portion of the phosphor screen. The arrangement of the body layers is disturbed and the appearance of the phosphor screen is impaired. Further, in the peripheral portion of the phosphor screen where the incident angle of the electron beam is large, the difference in height between the effective surface 5 and the reinforcing bead 16 is large, so that the deviation of the beam landing at the portion corresponding to the reinforcing bead 16 becomes large. , Color shift occurs,
Image quality is degraded.

In order to prevent the deterioration of the appearance and image quality of the phosphor screen, the height of the reinforcing bead 16 may be lowered, but if the height of the reinforcing bead 16 is lowered, the original purpose is doming. The inhibitory effect of is reduced.

[0009]

As described above, in order to suppress the doming of the shadow mask due to the collision of the electron beam, a strip-shaped reinforcing bead protruding in the phosphor screen direction is formed on the effective surface of the mask body, There are shadow masks with increased mechanical strength. In this shadow mask, the height of the reinforcing beads is constant on the effective surface, and is gradually lowered from the periphery of the effective surface so that the height becomes 0 at the boundary between the non-effective surface surrounding the effective surface, the skirt portion, and the skirt portion. It is formed or has a constant height from the center of the effective surface to the boundary between the ineffective surface and the skirt. Therefore, when a color picture tube is constructed using such a shadow mask, the phosphor layer is disturbed due to a large difference in height between the effective surface and the reinforcing beads in the peripheral portion of the phosphor screen, and the phosphor layer is disturbed. The appearance of the body screen is impaired. In addition, in the peripheral portion of the phosphor screen where the incident angle of the electron beam is large, the difference in height between the effective surface and the reinforcing bead causes a beam landing shift in the reinforcing bead corresponding part, which causes an image such as color shift. Problems such as deterioration of quality occur.

The present invention has been made in view of the above problems, and prevents the appearance and image quality of a phosphor screen from being deteriorated even when a reinforcing bead that sufficiently suppresses doming of a shadow mask is formed. The purpose is to

[0011]

An effective surface on which a large number of electron beam passage holes are formed in a predetermined array and an ineffective surface surrounding the effective surface face a phosphor screen formed on the inner surface of the panel at a predetermined interval. In a color picture tube having a shadow mask composed of a mask body having a skirt portion provided around the effective surface and the ineffective surface, and a mask frame attached to the skirt portion of the mask body, the shadow mask is an effective surface. A reinforcing bead is formed on the entire side that traverses the horizontal direction, and the height of this reinforcing bead is gradually reduced from the center of the effective surface to the boundary between the ineffective surface and the skirt, and the effective surface and the ineffective surface are The height of the reinforcing bead at the boundary was set to 2/3 or less of the height of the reinforcing bead at the center of the effective surface.

Further, the height h of the reinforcing bead at the central portion of the effective surface is 0.1t with respect to the plate thickness t of the mask body.
It was formed so that ≦ h ≦ 3t.

[0013]

As described above, the height of the reinforcing bead is gradually reduced from the center of the effective surface to the boundary between the ineffective surface and the skirt, and the height of the reinforcing bead at the boundary between the effective surface and the ineffective surface is reduced. Height is 2/3 of the height of the reinforcing bead at the center of the effective surface
With the following, the phosphor screen has a sufficient doming suppressing effect on the shadow mask, and reduces the disorder of the arrangement of the phosphor layers caused by the difference in height between the conventional effective surface and the reinforcing beads, and the phosphor screen. It is possible to prevent the deterioration of the appearance and the deterioration of the image quality due to the deviation of the beam landing.

Further, when the height h of the reinforcing bead at the central portion of the effective surface is formed to satisfy the relationship of 0.1t≤h≤3t, it has a necessary doming suppressing action and the appearance and image quality of the phosphor screen. It is possible to easily set a shadow mask that prevents deterioration of the.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings. FIG. 1 shows a color picture tube as the first embodiment. This color picture tube has an envelope composed of a rectangular spherical panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1. The inner surface of the panel 1 emits blue, green, and red light. A phosphor screen 3 composed of a striped three-color phosphor layer which is elongated in the vertical direction is formed, and a rectangular shadow mask 20 described later is arranged inside the phosphor screen 3 so as to face the phosphor screen 3.
On the other hand, in the neck 11 of the funnel 2, an electron gun 13 that emits the three electron beams 12B, 12G, 12R arranged in a row passing through the same horizontal plane is arranged. Then, the three electron beams 12B, 12G emitted from the electron gun 13,
12R is a deflection yoke 1 mounted outside the funnel 2.
The fluorescent screen 3 is deflected by a magnetic field generated by the magnetic field 4 and is horizontally and vertically scanned through the shadow mask 20 to form a structure for displaying a color image.

In the shadow mask 20, as shown in FIG. 2, a plurality of electron beam passage holes 21 are arranged in a line in a vertical direction (Y direction) via narrow bridges 22,
The vertical direction electron beam passage holes 21 are arrayed in a plurality of rows in the horizontal direction (X direction), and an effective surface 23 and a non-effective surface 24 surrounding the effective surface 23 (portions where electron beam passage holes are not formed). Is formed into a rectangular spherical surface having a predetermined curvature, and includes a mask body 26 having a skirt portion 25 provided on the periphery thereof, and a mask frame 27 attached to the skirt portion 25. By locking the frame holder 9 made of an elastic body with the stud pin 10 fixed to the panel 1, the mask body 26 is supported inside the panel 1 so as to face the phosphor screen.

Further, the mask body 26 of the shadow mask 20 has a reinforcing bead having a relatively wide width in the center thereof so as to horizontally traverse the effective surface 23 and the ineffective surface 24 surrounding the effective surface 23. 28 is formed. This reinforcing bead 28 projects toward the phosphor screen, and the height h of the effective surface 23 at the center is such that the boundary 29 between the ineffective surface 24 and the skirt 25 is the reinforcing bead end and the center of the effective surface 23. From the portion to the boundary portion 29 between the ineffective surface 24 and the skirt portion 25, and the height of the reinforcing bead 28 at the effective surface 23 and the ineffective surface 24 is 0 at the boundary portion 29. The height h of the reinforcing bead 28 at the center of the effective surface 23 is ⅔ or less. Further, the height h at the center of the effective surface 23 is formed in a relationship of 0.1t ≦ h ≦ 3t with respect to the plate thickness of the mask body 26.

As shown in FIG. 3, the mask body 26 has a flat plate-shaped flat mask in which electron beam passage holes are formed by photoetching, and has an effective surface and an ineffective surface surrounding the effective surface. A punch 33 having a molding die 32 for molding a reinforcing bead on the molding surface 31;
It can be molded by a press molding apparatus including a die 36 in which a concave portion 35 corresponding to a molding die 32 for molding a reinforcing bead is formed on a molding surface 34 having the same curvature as the molding surface 31 of the punch 33.

By the way, as described above, the shadow mask 2
The height h from the center of the effective surface 23 to the boundary portion 29 between the ineffective surface 24 and the skirt 25 on the mask body 26 of 0
Gradually decreases, and a reinforcing bead 28 is formed at the boundary portion 29 to be 0, and the height of the reinforcing bead 28 at the center of the effective surface 23 is set as described above with respect to the plate thickness of the mask body 26 as t. When the regulation is performed, deterioration of the appearance and image quality of the phosphor screen can be prevented while maintaining a sufficient suppressing effect on the doming of the shadow mask, which is the original purpose of the reinforcing beads.

That is, when there is a large difference in height between the effective surface and the reinforcing beads at the periphery of the effective surface, the phosphor layers are arranged in the peripheral portion of the phosphor screen formed by photo printing using the shadow mask as a photomask. Is disturbed and the appearance of the phosphor screen is deteriorated. However, when the reinforcing bead 28 is formed as in the shadow mask 20 of this example, the height of the effective surface and the reinforcing bead at the peripheral edge of the effective surface is maintained despite maintaining the strength required for suppressing the doming of the shadow mask. The arrangement of the phosphor layers due to the large difference can be less disturbed, and the deterioration of the appearance of the phosphor screen can be reduced. Further, the deviation of the beam landing in the peripheral portion of the phosphor screen 3 can be reduced, and the deterioration of image quality can be prevented.

Further, if the height h of the reinforcing bead 28 at the center of the effective surface 23 is restricted as described above, the reinforcing bead 2
8 from the central portion of the effective surface 23 to the ineffective surface 24 as described above.
And gradually decreases toward the boundary 29 between the skirt 25 and
Even if the boundary portion 29 is formed to have 0, a shadow mask having a sufficient suppressing effect on doming can be obtained.

That is, the relationship between the height h of the reinforcing bead and the purity drift (PD) based on the doming of the shadow mask is as shown by a curve 38 in FIG. 4, and the reinforcing bead is projected by 0.05 mm from the effective surface. Just by improving the purity drift by about 5%, if you make it protrude 0.1 mm,
It can be improved by about 10%. This indicates that a sufficient doming suppression effect can be obtained by setting the height h of the reinforcing bead to 0.1 t or more with respect to the plate thickness t (t = 1 mm) of the mask body. However, as can be seen from the curve 38, when the height h of the reinforcing bead exceeds 0.3 mm,
Although the height h of the reinforcing bead is high, the effect of improving the purity drift cannot be improved. On the other hand, if the height h of the reinforcing beads is increased, not only the peripheral portion of the phosphor screen,
The disorder of the arrangement of the phosphor layers in the middle part and the central part also becomes large,
The deviation of the beam launching becomes large, and the height h of the reinforcing bead is limited to 3t.

For the 19-inch and 21-inch color picture tubes, the height h of the reinforcing beads is 0.15 mm,
Similar to the generally conducted forcedness drift test, as shown in FIG. 5, a white screen 39 having a predetermined size is drawn on the left and right sides of the phosphor screen 3, and the purity drift is measured. As a result, the reinforcing beads are not formed in FIG. Curve 4
0, as shown by the curve 41 in the case where the reinforcing beads are formed, the purity drift can be significantly improved. For example, the movement amount of the purity drift after 2 minutes from the start of the operation of the color picture tube can be changed when the reinforcing beads are not formed. It was possible to improve by about 13%.

Next, some examples of reinforcing beads having different shapes will be described. In the above embodiment, a reinforcing bead is formed horizontally across the effective surface, and the height h of the reinforcing bead at the central portion of the effective surface is gradually reduced toward the boundary between the non-effective surface and the skirt. The reinforcing bead 28 has a constant height h from the central portion of the effective surface 23 to the periphery 43 of the effective surface 23, as shown in FIG. Is a boundary portion between the effective surface 23 and the ineffective surface, and the peripheral surface 44 is a reinforcing bead end.
The shape may be gradually reduced so that the peripheral edge 44 becomes zero.

Further, in the above embodiment, the reinforcing bead having a wide width is formed across the central portion in the horizontal direction from the effective surface to the ineffective surface. As shown in FIG. A plurality of relatively narrow (two in the illustrated example) reinforcing beads 28a, 28b that horizontally traverse 23.
You may comprise. Further, as shown in FIG. 9, the reinforcing beads 28a and 28b may be formed to have a wide width.

[0026]

EFFECTS OF THE INVENTION A reinforcing bead is formed on the entire side of the effective surface of the shadow mask that crosses the horizontal direction, and the height of the reinforcing bead is gradually lowered from the center of the effective surface to the boundary between the ineffective surface and the skirt. In addition, if the height of the reinforcing bead at the boundary between the effective surface and the ineffective surface is set to 2/3 or less of the height of the reinforcing bead at the central portion of the effective surface, a sufficient doming suppression effect on the shadow mask is obtained. In addition, while reducing the disorder of the arrangement of the phosphor layer due to the difference in height between the effective surface and the reinforcing beads, it prevents the deterioration of the appearance of the phosphor screen and also the deterioration of the image quality due to the deviation of the beam landing. A color picture tube to prevent can be constructed.

When the height h of the reinforcing bead at the central portion of the effective surface is set to satisfy the relation of 0.1t≤h≤3t, it has a necessary doming suppressing action and the appearance and image quality of the phosphor screen. It is possible to easily set a shadow mask that prevents deterioration of the.

[Brief description of drawings]

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

2 (a) is a plan view showing the configuration of the shadow mask, FIG. 2 (b) is a front view showing its cross section, FIG.
(C) is a side view similarly showing in section.

FIG. 3 is a diagram for explaining the molding of the mask body of the shadow mask.

FIG. 4 is a diagram showing the relationship between the height of reinforcing beads of the shadow mask and the purity drift.

FIG. 5 is a diagram for explaining a method of measuring the purity drift of a color picture tube.

FIG. 6 is a view showing the purity drift of a color picture tube in which a shadow mask having a reinforcing bead is arranged in comparison with that of a color picture tube in which a shadow mask having no reinforcing bead is arranged.

FIG. 7 is a cross-sectional view showing the shapes of reinforcing beads of different shadow masks.

FIG. 8 (a) is a plan view showing the shape of another different reinforcing bead of the shadow mask, and FIG. 8 (b) is a side view showing its cross section.

9 (a) is a plan view showing another different shape of a reinforcing bead of a shadow mask, and FIG. 9 (b) is a side view showing its cross section.

FIG. 10 is a diagram showing a configuration of a conventional color picture tube.

11 (a) is a plan view showing the configuration of a conventional shadow mask having reinforcing beads formed on the effective surface, FIG.
(B) is the front view shown in the cross section.

12 (a) and 12 (b) are views showing different shapes of the reinforcing beads.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Panel 3 ... Phosphor screen 13 ... Electron gun 20 ... Shadow mask 21 ... Electron beam passage hole 23 ... Effective surface 24 ... Ineffective surface 25 ... Skirt part 26 ... Mask body 27 ... Mask frame 28 ... Reinforcing bead 29 ... Non Boundary between the effective surface and the skirt portion 43 ... Near the peripheral edge of the effective surface 44 ... Perimeter of the effective surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Takahashi 1-9-2, Harara-cho, Fukaya-shi, Saitama Stock company Toshiba Fukaya electronics factory

Claims (2)

[Claims] 1. An effective surface on which a large number of electron beam passage holes are formed in a predetermined array and an ineffective surface surrounding the effective surface face a phosphor screen formed on the inner surface of the panel at a predetermined interval and the effective surface. In a color picture tube having a shadow mask composed of a mask body having a skirt portion provided around the ineffective surface and a mask frame attached to the skirt portion of the mask body, the shadow mask is effective. A reinforcing bead is formed on the entire side of the surface that crosses the horizontal direction, and the height of the reinforcing bead gradually decreases from the central portion of the effective surface to the boundary between the ineffective surface and the skirt portion, and the effective surface. The height of the reinforcing bead at the boundary between the non-effective surface and the effective surface is ⅔ or less of the height of the reinforcing bead at the center of the effective surface. Picture tube. 2. The height h of the reinforcing bead at the central portion of the effective surface is formed to have a relationship of 0.1t ≦ h ≦ 3t with respect to the plate thickness t of the mask body. Item 1. The color picture tube according to item 1.