JP3137621B2 - Cathode ray 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 cathode ray tube, and more particularly, to a cathode ray tube having a color selection electrode (shadow mask) which enhances visibility by improving the flatness of an image in an effective area of a panel. The present invention relates to a cathode ray tube having improved flatness of an image in an effective area of a panel to improve visibility and / or improved workability of a color selection electrode (shadow mask).

[0002]

2. Description of the Related Art In general, a cathode ray tube has a vacuum envelope composed of a glass panel having a substantially rectangular face plate and a glass funnel. In this cathode ray tube, an electron beam emitted from an electron gun disposed in the neck of the funnel is deflected by a deflection yoke mounted outside the funnel, and the deflected electron beam causes an inner surface of an effective area of a face plate to be deflected. Is scanned horizontally and vertically, and an image is displayed on the screen. In particular, in a color picture tube, the phosphor screen provided on the inner surface of the effective area of the panel is composed of a three-color phosphor layer that emits blue, green, and red light, and is replaced with an electron gun that generates a single electron beam. 3
An electron gun assembly for emitting an electron beam is provided at the neck of the funnel. The three electron beams emitted from the electron gun assembly are deflected by a deflection yoke, further selected by a shadow mask, and directed to a corresponding phosphor layer.
The phosphor screen is horizontally and vertically scanned by the electron beam, so that a color image is displayed on the screen.

In such a cathode ray tube, it is desirable to flatten the effective area of the panel and the phosphor screen from the viewpoint of easy viewing of an image. Many studies have already been made on the flattening of this panel.
The strength of the vacuum envelope made of glass, and the color picture tube has many problems such as the workability of a flat shadow mask and the vibration on a flat shadow mask. Thus, there is a problem that it is difficult to achieve both good image characteristics and maintenance of the mechanical characteristics of the panel mask.

Japanese Patent Application Laid-Open No. Hei 7-99030 discloses a color picture tube in which the inner and outer surfaces of the effective area of the panel are flat. However, when the effective area of the panel is formed in a plane, even if the side wall of the panel is tightened by a conventionally used reinforcing band to compensate for the strength of the vacuum envelope, the strength of the vacuum envelope may be reduced. Can not be secured.
That is, in a panel in which at least the center of the inner surface of the effective area is formed of a convex curved surface protruding in the outer surface direction, the convex curved surface of the inner surface of the effective area is retained by tightening the side wall portion with a reinforcing band, and the center of the effective area is held by atmospheric pressure. It is possible to compensate for the distortion of the concave portion. However, in a panel in which the inner surface of the effective area is a flat surface, there is a problem that a compensation effect cannot be obtained because the central portion is concave. Therefore, in such a panel, it is necessary to attach a safety panel or the like to the outer surface of the effective area, which may increase the thickness of the panel and increase the cost. In particular, increasing the thickness of the panel causes a phenomenon in which an image floats around the screen due to refraction of light rays on the panel glass as described later, and the visibility of flatness is deteriorated. further,
It is necessary to flatten the effective surface of the shadow mask in accordance with the inner surface of the effective area of the panel.However, compared to a curved shadow mask, the workability of a flattened shadow mask deteriorates, and However, there is a problem that costs increase.

[0005] Also, Japanese Patent Application Laid-Open No. 6-36710 discloses that
As a method of solving the phenomenon of floating of an image in the peripheral portion due to the refraction of the panel glass, a cathode ray tube in which an effective area of the panel is formed in a concave lens structure and has a structure to compensate for the floating of the image in the peripheral portion of the screen is disclosed. ing.

However, when a concave lens structure is employed as described above for a panel whose inner surface in the effective area is curved to the extent that a shadow mask in which the effective surface is formed into a curved surface can be applied, the peripheral portion of the effective area can be used. Is too thick, the transmittance in the peripheral portion is deteriorated, and the visibility of flatness from a viewpoint away from the tube axis is rapidly deteriorated.

Further, Japanese Patent Application Laid-Open No. 6-44926 discloses that
A cathode ray tube is disclosed in which a safety panel is attached to the outer surface of a panel having a curved surface having a curvature whose outer surface is substantially flat and whose inner surface is in a horizontal and vertical direction via a transparent resin layer.

In the cathode ray tube having such a structure, the strength of the vacuum envelope can be compensated. However, the problem that the transmittance is deteriorated in the peripheral portion and the visibility of the flatness is deteriorated from a viewpoint distant from the tube axis cannot be solved.

Japanese Patent Application Laid-Open No. Hei 9-245885 discloses a cathode ray tube having a substantially cylindrical outer surface and a horizontal inner surface having a curved surface, and Japanese Patent Application Laid-Open No. 10-64451 discloses a horizontal tube. The radius of curvature is infinite and the vertical direction is.
A color picture tube having a curved surface with a constant radius of curvature is disclosed. In particular, Japanese Patent Application Laid-Open No. 10-64451 discloses that the thickness of the peripheral portion of the effective area of the panel is set to 1.2 at the center in consideration of the floating of the image due to the refraction of light rays by the panel glass. A color picture tube of about 1.3 times is disclosed. However, in practice, with the above thickness difference, sufficient strength of the vacuum envelope by the reinforcing band cannot be obtained, and it is difficult to realize a cathode ray tube with reduced cost. Further, in the cathode ray tubes disclosed in these publications, only the visibility of flatness taking into account only the amount of dip at the diagonal edge (distance in the tube axis direction) from the center of the inner surface of the effective area of the panel is mentioned. No consideration is given to the visibility of the flatness caused by the cylindrical shape.

In Japanese Utility Model Publication No. 7-29566,
As shown in FIG. 7, there is shown a cathode ray tube that suppresses image distortion by making a line 2 (equal thickness line) connecting points having equal thicknesses of the panel 1 into a closed loop in the entire screen. I have.

However, with this configuration, the panel 1
The thicknesses of the horizontal axis end (X-axis end), vertical axis end (Y-axis end), and diagonal axis end (D-axis end) of the panel 1 are made equal, thereby suppressing distortion due to refraction of light rays in the panel 1. Effect is reduced. Further, the panel 1 has a problem that a peak is formed near the end of the diagonal axis, and the peak is easily visually recognized when the viewpoint is moved. Furthermore, in the case of a color picture tube, when the effective surface of the shadow mask is formed into a shape similar to the inner surface of the panel 1, the sides of the equal thickness line, that is, flat regions near the horizontal and vertical axis ends, Problems such as a decrease in strength for holding a curved surface occur. Therefore, such a color picture tube,
It is said that practical application is difficult.

[0012]

As described above, in the cathode ray tube, it is desirable to flatten the inner surface of the effective area of the panel and the phosphor screen from the viewpoint of easy viewing of images. However, when the inner surface of the effective area of the panel and the phosphor screen are flattened, there is a problem that the strength of the vacuum envelope made of glass is not sufficient. In addition, there is a problem that an image at the periphery of the screen floats due to the refractive index of the light beam on the panel glass, and visibility of the flatness is deteriorated. Further, in the color picture tube, there is a problem that workability of the shadow mask is also deteriorated.

It is an object of the present invention to secure the strength of a vacuum envelope by making the inner surface of a panel having a flat outer surface an appropriate curved surface, and to observe the flatness due to refraction of light rays in the panel glass. It is an object of the present invention to provide a cathode ray tube capable of suppressing deterioration of performance and further improving the processability of a color selection electrode (shadow mask) for a color picture tube.

[0014]

(1) A panel having a flat outer surface and a convex curved surface with the center of the inner surface projecting in the outer surface direction is defined as M in the horizontal direction and N in the vertical direction on the inner surface of the panel. In a cathode ray tube in which a substantially rectangular phosphor screen having an aspect ratio of M: N is formed, the inner surface of the panel is positioned on a horizontal axis and a vertical axis of the phosphor screen at a distance r from the center of the inner surface. And the amount of drop (difference along the tube axis) with respect to the center of the inner surface on the diagonal axis.
(R), ΔV (r), ΔD (r),

[0015]

(Equation 5)

[0016]

(Equation 6)

It is formed on a curved surface that satisfies the following.

(2) In the cathode ray tube of (1), the dip amount ΔD (r) on the diagonal axis of the phosphor screen of the panel.
Is the maximum drop ΔD (rMax), the drop amount ΔD (rMax) is set in the range of 5 mm to 20 mm.

(3) A panel having a flat outer surface and a convex curved surface with the center of the inner surface protruding in the outer surface direction. The inner surface of the panel has an aspect ratio (M: H in the horizontal direction and N in the vertical direction). A phosphor screen composed of N substantially rectangular phosphor layers of a plurality of colors is formed, and a central surface of the phosphor screen faces the phosphor screen and has a convex surface protruding in the direction of the phosphor screen. A substantially rectangular color selection electrode having an aspect ratio of M: N, where M is the vertical direction and N is disposed, and the color selection electrode selects a plurality of beams emitted from the electron gun to form a color image on a phosphor screen. In the cathode ray tube displaying, the convex surface of the color selection electrode is positioned at a distance r from the center of the convex surface with respect to the center of the convex surface on the horizontal axis, the vertical axis, and the diagonal axis of the color selection electrode. Each drop amount M (r) · △ V (r), △ DH
(R),

[0020]

(Equation 7)

[0021]

(Equation 8)

It is formed on a curved surface that satisfies.

(4) In the cathode ray tube of (3), when the drop amount on the diagonal axis of the color selection electrode △ DM (r) is the maximum drop amount △ DM (rMax), the maximum drop amount △ DM (RMax) is determined in the range of 5 mm to 20 mm.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color picture tube according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color picture tube according to an embodiment of the present invention. This color picture tube has a vacuum envelope composed of a substantially rectangular panel 12 provided with a skirt 11 around the effective area 10 and a funnel 13 in the form of a funnel. On the inner surface of the effective area 10 of the funnel 12, a phosphor screen 14 composed of a three-color phosphor layer emitting blue, green, and red light is formed. Further, a shadow mask 16 as a color selection electrode having a large number of electron beam passage holes provided on an effective surface 15 facing the phosphor screen 14 is disposed. On the other hand, an electron gun 19 that emits three electron beams 18B, 18G, 18R is arranged in the neck 17 of the funnel 13. Then, the three electron beams 18B, 18G emitted from the electron gun 19,
18R is deflected by a deflection yoke 20 mounted on the outside of the funnel 13, passes through the shadow mask 16 and is directed to the phosphor screen 14, which is horizontally and vertically moved by the electron beams 18B, 18G, 18R. By being scanned, the fluorescent screen 1
4, a color image is displayed.

The panel 12 has a flat effective area 10 having a flat outer surface, and the inner surface of the effective area 10 is formed as a convex curved surface whose center is projected toward the outer surface. When the length of the inner surface of the phosphor screen 14 in the horizontal direction (X-axis direction) is M and the length of the inner surface in the vertical direction (Y-axis direction) is N, the phosphor screen 14 has an almost rectangular aspect ratio of M: N. It is formed in a shape. The shadow mask 16 facing the phosphor screen 14 is an effective surface 15 corresponding to the inner surface shape of the effective area 10 of the panel 12, and the center thereof is formed as a convex curved surface protruding toward the phosphor screen 14. The effective surface 15 is formed in a substantially rectangular shape having an aspect ratio of M: N, where M is the horizontal distance of the effective surface 15 and N is the vertical distance.

In this embodiment, the inner surface of the effective area 10 of the panel 12 formed of a convex curved surface is located on a horizontal axis, a vertical axis, and a diagonal of the phosphor screen 14 at a distance r from the center of the inner surface. The amount of drop relative to the center on the axis (the difference between the center along the tube axis Z and the distance at a distance r from the center) is denoted by △ H (r), △ V (r), △ D
When (r) is used, this curved surface is

[0028]

(Equation 9)

[0029]

(Equation 10)

It is formed on a curved surface satisfying the conditions. Moreover,
Amount of drop ΔD at the diagonal axis end of phosphor screen 14
When (r) is the maximum drop amount ΔD (rMax), the maximum drop amount ΔD (rMax) is ΔD (rMax) = 5
It is set in the range of mm to 20 mm.

The effective surface 15 of the shadow mask 16, which is a convex curved surface, falls at a distance r from the center of the effective surface 15 with respect to the center on the horizontal axis, the vertical axis, and the diagonal axis. The quantity (the difference in distance between the center along the tube axis Z and a position at a distance r from the center) is denoted by HM
(R), △ VM (r), △ DM (r), the effective surface 15 is

[0032]

[Equation 11]

[0033]

(Equation 12)

The curved surface satisfies the following conditions. Moreover,
Depth of this effective surface 15 on the diagonal axis △ DM (r)
Is the maximum drop amount △ DM (rMax), the maximum drop amount △ DM (rMax) is △ DM (rMax) = 5
It is determined in the range of mm to 20 mm.

When the panel 12 and the shadow mask 16 have such curved surfaces, the visibility of the flatness of the image drawn on the phosphor screen 14 can be improved, and the strength and the strength of the vacuum envelope can be improved. The workability of the shadow mask 16 can be improved to provide sufficient strength.

Hereinafter, the panel 12 and the shadow mask 16 will be described.
The reason why it is preferable to have such a curved surface will be described.

In general, the visibility of the flatness of an image depends on the distortion generated in the reflected image and the distortion generated in the image formed on the phosphor screen. The reflected image includes a reflected image reflected from the outer surface of the effective area of the panel and a reflected image reflected from the inner surface. In general, regarding the distortion of the reflected image, since the intensity of the light beam reflected from the inner surface is small, it is sufficient to consider the reflected image generated by the light beam reflected from the outer surface. In a cathode ray tube whose outer surface is a curved surface, it is visually recognized that the flatness of the image is deteriorated due to distortion of the reflected image on the outer surface. In order to reduce the distortion of the reflected image on the outer surface, the radius of curvature of the outer surface may be increased, and the flatness of the flat surface can prevent the deterioration of the visibility of the flatness.

On the other hand, the image distortion caused by the phosphor screen is caused by the refraction of light rays in the effective area of the panel, and is changed depending on the viewpoint of viewing the image drawn on the phosphor screen. When the viewpoint is determined, there is a curved surface that does not cause distortion due to refraction. However, since the viewpoint for viewing the image is generally not constant, especially when viewing the image from a viewpoint left and right from the tube axis, that is, an oblique direction,
For a curved surface symmetric with respect to the tube axis, the distortion is not solved.

In order to explain the image distortion due to the refraction, in the case of a viewpoint with both eyes whose center is on the tube axis and parallel to the tube surface, that is, as shown in FIG. Flat plane, inner surface is distance r from center of panel 12
Is formed on a curved surface having a thickness of t (r) at a position, and a fluorescent screen (not shown) at a point A on the inner surface of the distance r.
Are emitted, and this emission is observed at the binocular viewpoints BL and BR whose center is located on the tube axis (Z) away from the outer surface of the effective area 10 of the panel 12 and which is parallel to the horizontal axis (H axis) of the tube surface. The case in which it is performed is described.

In FIG. 2, the light beam generated at the light point A passes through the panel 12 and is directed to the viewpoints BL and BR. It passes through GR and is directed to viewpoints BL and BR. Therefore, from the viewpoints BL and BR, the light point A is shifted upward (emerged) and looks as if it were at the point C. In other words, the virtual image point of the light spot A occurs at the position C between the inner surface and the outer surface of the panel 12.

Here, the distance from the outer surface to the floating position at the center of the inner surface of the panel is assumed to be tR, and a flat reference surface 22 located inside the outer surface of the effective area 10 within the distance tR along the tube axis Z is assumed. Considering the visibility of the image on the surface 22, the following is obtained.

On the reference surface 22, the light point A is shifted by the shift amount Δr, and the virtual image point C is seen. This virtual image point is generated downward by the shift amount Δt from the reference surface 22 along the tube axis direction. It will be. The shift amount Δr is
The direction away from the center of the panel 12 is defined as positive, and the shift amount Δt
Defines the viewpoint BL, BR direction to be positive. The reference surface 22 refers to a virtual plane on which light refraction does not occur on the panel 12. The smaller the deviation amounts Δr and Δt from the reference surface 22, the smaller the distortion due to refraction on the panel 12.

When a flat panel, that is, a panel having a constant thickness where t (r) = t (O) is viewed from the above viewpoint, the refractive index na of the atmosphere is obtained.
And the refractive index ng of the panel is usually ng ≒ 1.5, na ≒ 1.0, the diagonal dimension of the phosphor screen is about 16 to 20 inches, and the thickness t (r) of the effective area of the panel is 10 ~ 12
mm, the distance from the outer surface of the effective area to the viewpoint is L = 300
~ 600mm, interval es between both eyes BL, BR is 60 ~ 70m
Assuming the case of m, the deviation amounts Δr and Δt at the diagonal ends are
It is approximately 0.5 to 1.0 mm. Further, in order to eliminate distortion due to refraction when viewed from the viewpoint point, the diagonal end of the inner surface of the panel with respect to the center of the inner surface of the effective area is 0.7 to 1.0 mm, and the dip of the V end is zero. .
It is preferable to be a roughly spherical surface with a drop of 5 mm and an H end of about 0.5 to 0.8. In other words, the distortion of the image due to the refraction of the panel can be almost solved by forming the inner surface of the panel as described above.

However, in general, the viewpoint is likely to be located right and left from the tube axis, so that the peripheral portion of the single spherical surface rises and appears concave. In addition, the strength of the vacuum envelope and the shadow mask is reduced, and it is particularly difficult to form the effective surface of the shadow mask into a predetermined curved surface.

In order to solve this, it is necessary to consider increasing the thickness t (r) of the surrounding city while minimizing the distortion.

As a result of the analysis, even when the thickness t (r) of the peripheral portion is increased, the image pattern is reduced or shifted due to refraction for a specific image pattern, but the shape itself of the image pattern is changed. The inner shape that is not allowed is theoretically derived, and a practical panel shape and shadow mask shape have been designed.

Next, a theoretical explanation will be given below.

In a panel having a single spherical surface in which the outer surface of the effective area is a flat flat surface and the amount of diagonal end drop from the center of the inner surface is 10 to 15 mm, distortion due to refraction when viewed from the viewpoint on the tube axis. Are shown in FIGS. 3 (a) and 3 (b). FIG. 3A shows distortion of a concentric pattern centered on the center O of the effective area, and FIG. 3B shows distortion of a concentric rectangular pattern centered on the center O of the effective area. Have been. Here, a broken line 24 indicates a pattern without distortion.

The shift amount Δr due to refraction is in the negative direction (center direction) indicated by arrow 25. In a concentric pattern centered on the center O of the effective area, points t on the same circle have the same thickness t (r) and the same viewing angle θ, and thus have the same displacement Δr. The deviation amounts △ r at points on the diagonal axis (D axis), the horizontal axis (H axis), and the vertical axis (V axis) are represented by △ rD and △ r, respectively.
H, △ rV,

[0050]

(Equation 13)

Thus, the image pattern 26 is reduced as shown by the solid line, but the pattern shape does not change. However, in a concentric rectangular pattern centered on the center of the effective area, assuming that the distance from the center of the effective area to a point on the horizontal axis of the pattern 24 is r, assuming that the distance to the diagonal of the pattern 24 indicated by the broken line is r. ,

[0052]

[Equation 14]

The distance to a point on the vertical axis is

[0054]

(Equation 15)

Correspondingly, the thickness t (r) of the pattern 24 at the diagonal, horizontal and vertical axes is reduced,

[0056]

(Equation 16)

As a result, the image pattern 26 is reduced as shown by the solid line and is distorted into a barrel shape.

Therefore, the outer surface of the effective area of the panel is a flat plane, and the inner surface is a point on the diagonal axis at a distance r from the center of the effective area, as shown in FIG. And the thickness t (r) of each point on the rectangular pattern 24 connecting the points of the formula (20) on the vertical axis is constant, and the thickness t (r) in the diagonal axis direction is r ² The curved surface that increases in proportion to (a substantially uniform curvature) has a curved surface that suppresses the distortion caused by the difference in the viewing angle θ of each point on the phosphor screen (the thickness of the panel is as thick as less than 2 mm at the diagonal end). 5B, the image pattern 26 of the rectangular pattern 24 is reduced due to refraction, but the image pattern 26 is distorted as shown in FIG. 5B. There is no pattern. However, as shown in FIG. 5A, with respect to the concentric pattern 24 centered on the center O of the effective area, the thickness t (r) at each point on the pattern 24 differs depending on the position. The pattern 26 will shrink and distort into a pattern having a protrusion on the diagonal axis.

In the panel shape as shown in FIG. 4, the distortion of the rectangular image pattern can be suppressed, but the distortion of the concentric pattern becomes remarkable. In an actual use environment, a rectangular image pattern is used for a frequent festival. However, in a display such as a drawing, a concentric image pattern cannot be ignored. Practically, it is preferable to add a slightly more spherical component to the panel shape shown in FIG. 4 to obtain an inner surface shape that is an intermediate shape between the single spherical surface and the curved surface shown in FIG. In particular, in a color picture tube having a molding type shadow mask, when the shadow mask is molded into a shape similar to the panel shape shown in FIG. 4, flat regions are formed at the horizontal and vertical axis ends, and the curved surface of the shadow mask is maintained. The strength of the coating deteriorates. However, by adding the spherical component, flatness at the horizontal and vertical axis ends can be reduced. Therefore, the addition of a spherical component is also important in improving the strength of holding the curved surface of the shadow mask.

Specifically, on the inner surface of the effective area of the panel,
When a rectangular phosphor screen having an aspect ratio of M: N with a distance M in the horizontal direction and a distance N in the vertical direction is formed, a distance r from the center of the inner surface on the horizontal axis, the vertical axis, and the diagonal axis Depth of center of inner surface at point ΔH
(R), △ V (r), and △ D (r) may be the inner surface shapes satisfying the following Expressions 22 and 23.

[0061]

[Equation 17]

[0062]

(Equation 18)

Assuming that

[0064]

[Equation 19]

And

[0066]

(Equation 20)

In this case, not only is the distortion of the concentric image pattern increased, but also for the rectangular image pattern, pincushion-shaped distortion occurs due to the viewing angle difference, and the peak on the diagonal axis becomes an acute angle. Therefore, when the viewpoint is separated from the tube axis, the peak can be easily recognized, which is not preferable. Further, since the horizontal and vertical axis ends are extremely flat, the strength of the color picture tube for holding the curved surface of the shadow mask is reduced, which is practically difficult.

In contrast to a panel having such an inner surface shape, in a panel in which the above-mentioned inner surface shape is a single spherical surface,

[0069]

(Equation 21)

As described above, the distortion of the rectangular image pattern increases.

That is, the inner surface shape of the effective area of the panel is a curved surface defined by the above equations (22) and (23),
Further, the dip amount at the end of the diagonal axis (r = rMax) △ D
By setting (rMax) to 5 m to 20 mm, the visibility of flatness is better than that of other curved surfaces where the amount of dip at the diagonal axis end is the same as the amount of dip at the horizontal axis end and vertical axis end. The panel can be excellent.

The relationship between the distance r in the diagonal axis direction from the center of the effective area of the panel and the thickness t (r) is considered in view of the fact that the viewpoint is often left and right away from the tube axis. , T (r) increase in proportion to r ² and have a substantially uniform curvature.

Further, it is preferable in terms of the design of the shadow mask that the inner surface shape of the effective area of the panel be the above-mentioned curved surface. That is, when the inner surface of the effective area is a curved surface defined by the above formulas (22) and (23), when the dip amount ΔD (rMax) at the diagonal axis end is the same, the horizontal axis end and the vertical The amounts of depression ΔH (rMax) and ΔV (rMax) at the shaft ends can be made larger than those of the panel having a single spherical surface. As a result, it is possible to increase the curvature of the effective surface of the shadow mask formed in a shape corresponding to the inner surface shape of the effective area in the horizontal axis and the vertical axis direction, and the elongation and the tensile strength required for forming the effective surface of the shadow mask, Furthermore, thermal deformation of the effective surface caused by the collision of the electron beam can be reduced.

Hereinafter, specific examples of the curved surface shapes of the inner surface of the effective area of the panel and the effective surface of the shadow mask, which were implemented for a color picture tube having a diagonal dimension of 18 inches, will be described.

(Embodiment) FIG. 6 shows the amount of drop of each part with respect to the center of the inner surface of the effective area of the panel of a color picture tube having a diagonal dimension of 18 inches by contour lines, and Table 1 by the contour lines. The drop amount in the regions zl to z10 is shown. further,
Table 2-1 and Table 2-2 show the drop amount of each part by the horizontal and vertical coordinates, and Table 3-1 and Table 2-2 show the horizontal curvature radius Rx of each part, Table 4-1 and Table 4- 2 perpendicular radius of curvature R
y.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

[Table 4]

[0080]

[Table 5]

[0081]

[Table 6]

[0082]

[Table 7]

FIG. 6 and Tables 2-1 to 2-2 and 3-
1. The values in Table 3-2 are defined as Z, where the drop amount with respect to the center of the inner surface of the effective area is Z

[0084]

(Equation 22)

This is given by Here, i and j are integers 0 to 2, and a is a coefficient shown in Table 5.

[0086]

[Table 8]

In addition, horizontal, vertical. The radius of curvature Rx in the direct direction,
Ry is

[0088]

(Equation 23)

[0089]

(Equation 24)

Is obtained from the above.

When the inner surface shape of the effective area is determined in this way, as shown in Table 2, the deviation amounts ΔD (rMax), ΔH
(RMax), the drop amount ZD (r = 228 mm) at the diagonal axis end, horizontal axis end, and vertical axis end corresponding to ΔV (rMax), Z
H (r = 180 mm) and ZV (r = 140 mm) are about 10.4 mm, 7.2 mm, and 6.7 mm, respectively.

Further, when the inner surface shape of the effective area is determined as described above, the effective surface of the shadow mask defined corresponding to the inner surface shape can sufficiently expand in the horizontal and vertical directions at the time of molding. In addition, the radius of curvature in one of the horizontal and vertical directions is reduced to about 2000 mm, so that the tensile strength and the thermal deformation due to the collision of the electron beam can be reduced.

Although the above embodiment has been described with reference to a color picture tube, the present invention can be applied to a cathode ray tube other than a color picture tube.

[0094]

As described above, by defining the outer surface of the panel as a plane and defining the amount of depression relative to the center of the inner surface, the strength of the vacuum envelope is ensured and the display is performed on the phosphor screen formed on the inner surface. To improve the visibility of the flatness of the resulting image. it can. Furthermore, for color picture tubes,
The workability of the shadow mask can be improved to avoid a decrease in strength.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a structure of a color picture tube according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining image distortion caused by refraction of light rays in an effective area of a panel.

FIG. 3A is a view for explaining distortion caused by refraction of a concentric pattern centered on the center of the effective area when the inner surface of the effective area of the panel is formed of a single spherical surface, and FIG.
FIG. 8 is a diagram for explaining distortion due to refraction of a concentric rectangular pattern centered on the center of an effective area.

FIG. 4 is an explanatory view of a panel in which a spherical component having a wedge of less than 2 m at a diagonal end is added to an inner surface shape having a constant thickness at each point on a rectangular pattern centered on the center of an effective area. .

5A is a diagram for explaining distortion due to refraction of a concentric pattern centered on the center of the effective region in the panel shown in FIG. 4, and FIG. 5B is a diagram illustrating the center of the effective region as a center; FIG. 6 is a diagram for explaining distortion due to refraction of a concentric rectangular pattern.

FIG. 6 is a diagram showing, with contour lines, the amount of drop of each part with respect to the center of the inner surface of the effective area of the panel of the color picture tube having a diagonal size of 18 inches.

FIG. 7 is a diagram showing the shape of a conventional improved panel.

[Explanation of symbols]

 12 panel 14 phosphor screen 15 effective surface 16 shadow mask

Claims (4)

(57) [Claims] 1. An aspect ratio having a panel whose outer surface is a flat surface and whose center of the inner surface is a convex curved surface protruding in the direction of the outer surface, wherein the inner surface of the panel has a horizontal distance of M and a vertical distance of N. Is a cathode ray tube on which a substantially rectangular phosphor screen of M: N is formed, wherein the inner surface of the panel is a distance r from the center of the inner surface of the panel.
At the horizontal, vertical, and diagonal axes of the phosphor screen at the position of the inner surface of the phosphor screen, respectively, △ H (r), △ V (r), △ D (r) ), (Equation 2) A cathode ray tube characterized by being formed on a curved surface satisfying the following. 2. When the amount of dip ΔD (r) on the phosphor screen diagonal axis of the panel is the maximum amount of dip ΔD (rMax), the maximum amount of dip ΔD (rMax) is 5 mm to 2 mm.
2. The cathode ray tube according to claim 1, wherein the distance is set within a range of 0 mm. 3. An aspect ratio having a panel whose outer surface is a flat surface and whose center is a convex curved surface protruding in the direction of the outer surface, wherein the inner surface of the panel has a horizontal distance of M and a vertical distance of N. Is formed of a phosphor screen of a plurality of M: N, substantially rectangular phosphor layers of a plurality of colors. The phosphor screen is opposed to the phosphor screen, and the center is formed of a convex curved surface protruding in the panel direction. A substantially rectangular color selection electrode having an aspect ratio of M: N, where M is the distance in the direction and N is the distance in the vertical direction, is used to select a plurality of beams emitted from the electron gun by the color selection electrode. In a cathode ray tube displaying a color image on a phosphor screen, the convex surface of the color selection electrode is at a distance r from the center of the convex surface.
At the horizontal axis, the vertical axis, and the diagonal axis of the color selection electrode at the position of 凸 (r), △ VM (r), △ DM ( r), (Equation 4) A cathode ray tube formed on a curved surface that satisfies. 4. A drop ΔD on a diagonal axis of a color selection electrode.
4. The cathode ray tube according to claim 3, wherein when M (r) is a maximum drop amount △ DM (rMax), the drop amount △ DM (rMax) is set in a range of 5 mm to 20 mm.