JP3345513B2 - Color picture tube - Google Patents

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 a reinforcing bead is formed on an effective surface of a shadow mask to improve the mechanical strength of the shadow mask.

[0002]

2. Description of the Related Art In general, a color picture tube has, as shown in FIG. 10, an envelope comprising a substantially rectangular spherical panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1. On the inner surface of the panel 1, a phosphor screen 3 composed of a three-color phosphor layer in the form of dots or stripes emitting blue, green, and red light is formed. Are arranged. The shadow mask 4 is formed into a spherical shape having a predetermined curvature, and a plurality of electron beam passage holes are 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 frame holder 9 attached to the mask frame 8 is supported on the inside of the panel 1 by engaging a stud pin 10 provided on the panel 1. On the other hand, the three electron beams 12B, 12G, 1
An electron gun 13 for emitting 2R is provided.

The shadow mask 4 is for selecting the three electron beams 12B, 12G, and 12R emitted from the electron gun 13 so as to be correctly incident on the three-color phosphor layer. The three electron beams 12B, 12G, and 12R are deflected by a magnetic field generated by a deflection yoke 14 mounted outside the funnel 2, and the deflected electron beams 12B, 12G, and 12R are selected by the shadow mask 4 and fluorescent light is emitted. Body screen 3 horizontal,
The structure is such that a color image is displayed by performing vertical scanning.

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

As means for suppressing the doming of the shadow mask 4, as shown in FIG. 11, a band-shaped reinforcing bead 16 protruding toward the phosphor screen is formed on the effective surface 5 so that the mechanical strength of the mask body 7 is reduced. (Japanese Patent Application Laid-Open No. 5-258679) has been proposed. As shown in FIG. 12A, the reinforcing bead 16 has a constant height on the effective surface 5 and gradually lowers the height from the periphery of the effective surface 5 so that a non-effective surface 17 surrounding the effective surface 5 is formed. And skirt 18
12 (b), or from the center of the effective surface 5 to the boundary 19 between the non-effective surface 17 and the skirt 18 as shown in FIG. The height is fixed.

Therefore, when a color picture tube is formed by using the shadow mask 4 on which the reinforcing beads 16 are formed, the appearance of the phosphor screen and the quality of an 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 photomask, and light emitted from a light source disposed at a position corresponding to an electron gun. The shadow mask 4 is formed by printing a pattern of electron beam passing holes on a screen forming member layer such as a phosphor slurry layer formed on the inner surface of the substrate. Therefore, in the shadow mask 4 in which the reinforcing beads 16 are formed as described above, since the height difference between the effective surface 5 and the reinforcing beads 16 at the periphery of the effective surface 5 is large, the fluorescent The arrangement of the body layers is disturbed, and the appearance of the phosphor screen is impaired. Also, 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 increases. Causes color shift,
Degrades image quality.

In order to prevent the appearance and image quality of the phosphor screen from deteriorating, the height of the reinforcing bead 16 may be reduced. However, if the height of the reinforcing bead 16 is lowered, the original purpose of doming is obtained. The inhibitory action 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 band-shaped reinforcing bead is formed on the effective surface of the mask body and protrudes toward the phosphor screen. There is a shadow mask with increased mechanical strength. In this shadow mask, the height of the reinforcing bead is made constant on the effective surface, and gradually lowered from the periphery of the effective surface so that the height becomes zero at the boundary between the non-effective surface surrounding the effective surface, the skirt portion, and the skirt. 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 formed using such a shadow mask, the arrangement of the phosphor layers 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 fluorescent screen is disturbed. The appearance of the body screen is impaired. Also, due to the large difference in height between the effective surface and the reinforcing bead at the periphery of the phosphor screen where the electron beam incident angle is large, a beam landing shift occurs in the portion corresponding to the reinforcing bead, and images such as color shift Problems such as deterioration of quality occur.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and prevents the appearance and image quality of a phosphor screen from deteriorating even if a reinforcing bead for sufficiently suppressing doming of a shadow mask is formed. The purpose is to:

[0011]

Means for Solving the Problems An effective surface in which a large number of electron beam passage holes are formed in a predetermined arrangement and a non-effective surface surrounding the effective surface are opposed to 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 provided with a skirt portion around the effective surface and the non-effective surface and a mask frame attached to the skirt portion of the mask body, the shadow mask has an effective surface. A reinforcing bead is formed on the entire side crossing the horizontal direction, and 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 portion, and the height of the effective surface and the ineffective surface is reduced. 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 center of the effective surface is 0.1 t with respect to the thickness t of the mask body.
.Ltoreq.h.ltoreq.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 should be 2/3 of the height of the reinforcing bead at the center of the effective surface
In 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 bead. Can be prevented from deteriorating in appearance, and image quality can be prevented from deteriorating due to deviation in beam landing.

Further, when the height h of the reinforcing bead at the center of the effective surface is formed in a relationship of 0.1t ≦ h ≦ 3t, it has a necessary doming suppressing action, and has the appearance and image quality of the phosphor screen. It is possible to easily set a shadow mask for preventing deterioration of the image.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments. FIG. 1 shows a color picture tube according to 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, and the inner surface of the panel 1 emits blue, green and red light. A phosphor screen 3 composed of a three-color phosphor layer in a vertically elongated stripe shape is formed, and a rectangular shadow mask 20 to be described later is disposed inside the phosphor screen 3 so as to face the phosphor screen 3.
On the other hand, an electron gun 13 that emits three electron beams 12B, 12G, and 12R arranged in a line in the same horizontal plane is disposed in the neck 11 of the funnel 2. Then, the three electron beams 12B, 12G,
Deflection yoke 1 with 12R mounted outside funnel 2
The fluorescent screen 3 is deflected by the magnetic field generated by the magnetic field 4, and scans the phosphor screen 3 horizontally and vertically via the shadow mask 20, thereby forming a structure for displaying a color image.

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

Further, the mask body 26 of the shadow mask 20 has a reinforcing bead having a relatively large width w at the center thereof so as to cross the effective surface 23 and the non-effective surface 24 surrounding the effective surface 23 in the horizontal direction. 28 are formed. The reinforcing bead 28 protrudes toward the phosphor screen, and the height h at the center of the effective surface 23 is determined by setting the boundary 29 between the non-effective surface 24 and the skirt portion 25 as a reinforcing bead end. From the portion to the boundary portion 29 between the non-effective surface 24 and the skirt portion 25, the shape gradually decreases to zero at the boundary portion 29, and the height of the reinforcing bead 28 at the effective surface 23 and the non-effective surface 24 is And the height h of the reinforcing bead 28 at the center of the effective surface 23 is not more than 2/3. The height h at the center of the effective surface 23 is formed such that the thickness of the mask body 26 is 0.1t ≦ h ≦ 3t with respect to t.

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

By the way, as described above, the shadow mask 2
0 of the mask body 26 from the center of the effective surface 23 to the boundary 29 between the non-effective surface 24 and the skirt 25.
Gradually decreases and forms a reinforcing bead 28 that becomes 0 at the boundary 29, and the height of the reinforcing bead 28 at the center of the effective surface 23 is determined by the thickness of the mask body 26 with respect to t as described above. When regulated, the appearance and image quality of the phosphor screen can be prevented from deteriorating while maintaining a sufficient effect of suppressing the doping of the shadow mask, which is the original purpose of the reinforcing bead.

That is, if the height difference between the effective surface and the reinforcing bead at the periphery of the effective surface is large, the arrangement of the phosphor layers at the periphery of the phosphor screen formed by the photo printing method using the shadow mask as a photomask. 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 between the effective surface and the reinforcing bead at the periphery of the effective surface is maintained despite maintaining the strength necessary for suppressing doming of the shadow mask. Disturbance in the arrangement of the phosphor layers due to the large difference can be reduced, and deterioration in the appearance of the phosphor screen can be reduced. Further, the deviation of the beam landing at the peripheral portion of the phosphor screen 3 can be reduced, and the deterioration of the image quality can be prevented.

Further, when the height h of the reinforcing bead 28 at the center of the effective surface 23 is regulated as described above, the reinforcing bead 2
8 from the center of the effective surface 23 to the non-effective surface 24 as described above.
And gradually decreases toward the boundary portion 29 of the skirt portion 25,
Even if it is formed to be 0 at the boundary portion 29, it is possible to obtain a shadow mask having a sufficient effect of suppressing doming.

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, in which the reinforcing bead projects 0.05 mm from the effective surface. Alone, the purity drift can be improved by about 5%.
It can be improved by about 10%. This indicates that by setting the height h of the reinforcing beads to 0.1 t or more with respect to the thickness t of the mask main body (t = 1 mm), a sufficient doming suppression effect can be obtained. However, as can be seen from the curve 38, when the height h of the reinforcing bead becomes 0.3 mm or more,
Although the height h of the reinforcing bead is high, the effect of improving the purity drift cannot be improved. On the other hand, when the height h of the reinforcing bead is increased, not only the peripheral portion of the phosphor screen,
The disorder of the arrangement of the phosphor layers in the middle and the center also increases,
The deviation of the beam landing also increases, 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 bead is 0.15 mm,
As shown in FIG. 5, similar to the commonly performed forced drift drift test, a white screen 39 of 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, no reinforcing beads are formed in FIG. Case 4
0, the purity drift can be greatly improved as shown by the curve 41 when the reinforcing bead is formed. For example, the movement amount of the purity drift two minutes after the start of the operation of the color picture tube is reduced by the case where the reinforcing bead is not formed. An improvement of about 13% was achieved.

Next, some examples of reinforcing beads having different shapes will be described. In the above embodiment, a reinforcing bead that crosses the effective surface in the horizontal direction is formed, and the height h of the reinforcing bead at the center of the effective surface gradually decreases toward the boundary between the non-effective surface and the skirt portion, The reinforcing bead 28 is formed to have a constant height h from the center of the effective surface 23 to the vicinity 43 of the periphery of the effective surface 23 as shown in FIG. Are used as the reinforcing bead ends at the peripheral edge 44, which is the boundary between the effective surface 23 and the non-effective surface,
May be gradually reduced so as to become 0 at the peripheral edge 44 of the light emitting element.

Further, in the above embodiment, a wide reinforcing bead is formed so as to extend horizontally across the center from the effective surface to the ineffective surface. This reinforcing bead is, as shown in FIG. A plurality of (two in the illustrated example) reinforcing beads 28a, 28b having a relatively narrow width that crosses horizontally in the horizontal direction.
May be configured. Further, as shown in FIG. 9, the width of the reinforcing beads 28a, 28b may be widened.

[0026]

According to the present invention, a reinforcing bead is formed on the entire side crossing the horizontal direction of the effective surface of the shadow mask, and the height of the reinforcing bead is gradually reduced from the center of the effective surface to the boundary between the non-effective surface and the skirt. When the height of the reinforcing bead at the boundary between the effective surface and the non-effective surface is set to not more than 2/3 of the height of the reinforcing bead at the center of the effective surface, a sufficient doming suppressing effect on the shadow mask can be obtained. In addition to reducing the disorder of the arrangement of the phosphor layers due to the difference in height between the effective surface and the reinforcing bead, the appearance of the phosphor screen is prevented from deteriorating, and the image quality is degraded due to beam landing deviation. A color picture tube to be prevented can be configured.

Further, when the height h of the reinforcing bead at the center of the effective surface is formed so as to satisfy the relation of 0.1t ≦ h ≦ 3t, it has the necessary doming suppressing action, and has the appearance and image quality of the phosphor screen. It is possible to easily set a shadow mask for preventing deterioration of the image.

[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 the shadow mask, FIG. 2B is a front view showing a cross section thereof, and FIG.
(C) is a side view similarly shown by the cross section.

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

FIG. 4 is a diagram showing the relationship between the height of a reinforcing bead 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 diagram showing the purity drift of a color picture tube provided with a shadow mask having a reinforcing bead formed thereon as compared with that of a color picture tube provided with a shadow mask having no reinforcing bead formed thereon.

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

FIG. 8A is a plan view showing the shape of another different reinforcing bead of a shadow mask, and FIG. 8B is a side view showing a cross section thereof.

FIG. 9A is a plan view showing another different reinforcing bead shape of the shadow mask, and FIG. 9B is a side view showing a cross section thereof.

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

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

12 (a) and 12 (b) are diagrams showing different shapes of the reinforcing bead.

[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 ... Reinforcement bead 29 ... Non Boundary portion between effective surface and skirt 43... Near periphery of effective surface 44.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Osamu Takahashi 1-9-2, Hara-cho, Fukaya-shi, Saitama Prefecture Toshiba Fukaya Electronics Factory (56) References JP-A-5-258679 (JP, A) Kaisho 51-150266 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 29/07 H01J 9/14

Claims (2)

(57) [Claims] 1. An effective surface in which a large number of electron beam passage holes are formed in a predetermined arrangement and a non-effective surface surrounding the effective surface are opposed to a phosphor screen formed on an inner surface of a panel at a predetermined interval, and the effective surface is formed. And a mask main body provided with a skirt portion around the non-effective surface and a mask frame attached to the skirt portion of the mask main body. A reinforcing bead is formed on the entire side crossing the horizontal direction of the surface, and the height of the reinforcing bead gradually decreases from the center of the effective surface to the boundary between the non-effective surface and the skirt portion, and The height of the reinforcing bead at the boundary between the reinforcing bead and the ineffective surface is not more than 2/3 of the height of the reinforcing bead at the center of the effective surface. Picture tube. 2. The method according to claim 1, wherein a height h of the reinforcing bead at a central portion of the effective surface is formed in a relationship of 0.1t ≦ h ≦ 3t with respect to a thickness t of the mask body. Item 7. A color picture tube according to Item 1.