JP2006260979A - Color picture tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color picture tube having good visibility, hardly generating deterioration of color purity due to doming, although a shadow mask with excellent moldability and strength is provided. <P>SOLUTION: Radius of curvature of an outer face of a face panel is not less than 10 m. On condition that the radius of curvature of XZ cross section of the shadow mask 4 on a point P(x, y) on a perforated area of which X-coordinate is x, and Y-coordinate is y, the perforated area 41 has at least one point P<SB>(0, ym1)</SB>fulfilling Ry<SB>(0, 0)</SB>> Ry<SB>(0, ym1)</SB>[wherein, 0.4S≤ym1≤0.8S], and at least a pair of points P<SB>(xm1, 0)</SB>, P<SB>(xm1, ym2)</SB>fulfilling Ry<SB>(xm1, 0)</SB><Ry<SB>(xm1, ym2)</SB>[wherein, 0.4L≤xm1≤0.8L, 0.4S≤ym2≤0.8S]. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color picture tube provided with a shadow mask.

  In general, as shown in FIG. 6, the color picture tube has a substantially rectangular face panel 1 provided with a skirt portion 1b around an effective portion 1a having a curved surface, and a funnel-shaped funnel 2 joined to the skirt portion 1b. A vacuum envelope 9 consisting of On the inner surface of the effective portion 1a of the panel 1, a substantially rectangular fluorescent light composed of a black non-luminescent material layer and phosphors of three colors of green, blue, and red embedded in a gap between the black non-luminescent material layer. A body screen 3 is provided. Each phosphor is formed in a stripe shape along the short side direction, and a large number are arranged in the long side direction. A shadow mask structure 5 is provided opposite to the phosphor screen 3. The shadow mask structure 5 includes a shadow mask 4 in which a large number of electron beam passage holes are formed, and a substantially rectangular mask frame 11 that holds the shadow mask 4 at a skirt around the shadow mask 4. The shadow mask structure 5 is fixed to the face by engaging an elastic support (not shown) attached to the mask frame 11 with a stud pin (not shown) provided on the inner wall surface of the skirt portion 1b of the face panel 1. It is attached to the panel 1.

  An electron gun 7 that emits three electron beams 6B, 6G, and 6R is disposed in the neck 2a of the funnel 2. An internal magnetic shield 10 attached to the mask frame 11 is disposed inside the large diameter portion of the funnel 2. A deflection device 8 is mounted on the outer peripheral surface of the funnel 2. The three electron beams 6B, 6G, and 6R emitted from the electron gun 7 are deflected by the magnetic field generated by the deflecting device 8 and pass through the electron beam passage hole of the shadow mask 4 to move the phosphor screen 3 in the horizontal and vertical directions. A color image is displayed by scanning.

  The shadow mask 4 has a perforated region in which a large number of electron beam passage holes for selecting the three electron beams 6B, 6G, and 6R emitted from the electron gun 7 with respect to the three-color phosphor are formed, and the perforated area. A main surface portion formed of a non-porous region surrounding the outer periphery of the region, and a skirt portion that is bent substantially at right angles to the main surface portion and is connected to the main surface portion.

  In general, in order to display an image without color shift on the phosphor screen 3 of the color picture tube, the three electron beams that have passed through the electron beam passage holes formed in the shadow mask 4 correctly land on the three-color phosphor. There must be. For this purpose, it is necessary to maintain the face panel 1 and the shadow mask 4 in a predetermined relationship, and in particular, the distance (q value) between the phosphor screen 3 and the perforated region of the shadow mask 4 facing the phosphor screen 3 is. It is necessary to be within a predetermined tolerance.

  Incidentally, in recent years, in order to improve the visibility, it has been desired to increase the radius of curvature of the outer surface of the effective portion 1a of the face panel 1 so as to be close to a flat surface. In this case, from the viewpoint of the atmospheric pressure strength and visibility of the vacuum envelope 9, it is necessary to increase the radius of curvature of the inner surface of the effective portion 1a. When the radius of curvature of the inner surface of the effective portion 1a is increased, it is necessary to increase the radius of curvature of the perforated region of the shadow mask 4 in order to obtain an appropriate beam landing.

  However, if the radius of curvature of the perforated region of the shadow mask 4 is increased, the curved-surface holding strength of the shadow mask is reduced, which causes the following problem.

  For example, the shadow mask 4 is likely to be locally deformed in the manufacturing process or thermally deformed in the manufacturing process of the color picture tube. Such deformation of the shadow mask 4 causes a landing position shift of the electron beam with respect to the phosphor screen 3, and causes a deterioration in color purity of the display image. Further, the shadow mask 4 is liable to be deformed by vibrations or impacts received during the transportation of the color picture tube. In order to suppress this, care must be taken in the packaging of the color picture tube and handling during transportation. Further, when a color picture tube is incorporated in a TV set, the shadow mask 4 is likely to resonate due to sound from a speaker, and color purity deterioration (howling) is likely to occur due to the resonance.

  In the color picture tube provided with the shadow mask 4, the amount of the total electron beam emitted from the electron gun 7 passes through the electron beam passage hole of the shadow mask 4 and reaches the phosphor screen 3 due to its operating principle. The other electron beam collides with the shadow mask 4 and is converted into thermal energy. Accordingly, the shadow mask 4 is heated, and the resulting thermal expansion causes the shadow mask 4 to deform so as to bulge toward the phosphor screen 3 side, so-called doming is performed. When the distance (q value) between the phosphor screen 3 and the shadow mask 4 exceeds the allowable range due to this doming, the landing position of the electron beam with respect to the phosphor screen 3 is shifted, and the color purity is deteriorated.

  The magnitude of the landing position shift of the electron beam due to the thermal expansion of the shadow mask 4 varies greatly depending on the brightness of the displayed image pattern, the duration of the pattern, and the like. In particular, when a high-luminance image pattern is displayed locally, local doming occurs, and a local landing position shift occurs within a short time. In this local doming, the landing position deviation amount is also large.

  As shown in FIG. 7, the center of the shadow mask 4 (that is, the point where the tube axis (Z axis) intersects) is P0, and the axis perpendicular to the tube axis and parallel to the long side of the perforated region 41 is the long axis (X axis). ), An axis orthogonal to the tube axis and the long axis and parallel to the short side of the perforated region 41 is defined as a short axis (Y axis). Further, an interval along the long axis between the center P0 and the outer peripheral end of the perforated region 41 is L. The local doming appears most when the high luminance pattern is displayed in the elliptical region 30 including the point P1 on the long axis separated from the center P0 by (2/3) × L. In the region on the phosphor screen 3 corresponding to 30, the landing position deviation of the electron beam becomes the largest.

As the radius of curvature of the perforated region 41 of the shadow mask 4 increases, the amount of doming increases, so the amount of landing position deviation of the electron beam also increases and the color purity is greatly degraded. For this reason, in a color picture tube in which the outer surface of the effective portion 1a of the face panel 1 is substantially flat, as a material for the shadow mask 4, in general, iron and nickel having a low thermal expansion coefficient are the main components in order to suppress doming. An alloy is used. For example, an iron-nickel alloy such as 36Ni amber alloy is used. The thermal expansion coefficient of such an alloy is 1 to 2 × 10 ⁻⁶ at 0 to 100 ° C., which is effective for suppressing doming, but is high in cost, and further, the iron-nickel alloy is annealed after annealing. Since it has great elasticity, it is difficult to form a curved surface, and it is difficult to obtain a desired curved surface. For example, even if annealing is performed at a high temperature as high as 900 ° C., the yield point strength is about 28 × 10 ⁷ N / m ² , and generally 20 × 10 ⁷ N / m ^2, which is a yield point strength considered to be easy to mold. A considerable amount of high temperature treatment is required to make the following. Therefore, it is particularly difficult to process the shadow mask 4 having a large curvature radius of the perforated region 41 by press molding using this material.

  If the molding process is insufficient and an undesired stress remains in the shadow mask 4 after molding, the residual stress causes a change in the shape of the shadow mask 4 during the manufacturing process of the color picture tube. As a result, the beam landing position is shifted and the color purity is greatly deteriorated.

On the other hand, if the material is composed mainly of high-purity iron, the yield point strength can be reduced to 20 × 10 ⁷ N / m ² or less by annealing at about 800 ° C., so that the molding process is very easy. . Therefore, it is not necessary to keep the mold temperature at the time of molding, which is essential for the amber alloy, and the productivity is also good.

However, the thermal expansion coefficient of such high-purity iron-based material is as large as about 12 × 10 ⁻⁶ at 0 to 100 ° C., which is disadvantageous for doming. When applied to a color picture tube whose outer surface 1a is substantially flat, the color purity is remarkably deteriorated, which is a serious problem.

  Patent Document 1 discloses a substantially cylindrical surface shadow mask in which the radius of curvature in the major axis direction is almost infinite, and the radius of curvature in the minor axis direction is substantially constant regardless of the position in the major axis direction. Yes. Such a shadow mask has a certain effect for suppressing doming, but there is a problem that a sufficient effect cannot be obtained when an inexpensive iron material is used. In addition, measures for curved surface holding strength were not sufficient.

Patent Document 2 discloses a color picture tube whose curved surface holding strength is improved by defining the radius of curvature of a shadow mask, but measures for suppressing doming are insufficient, and a particularly inexpensive iron material is used. The shadow mask was a big problem.
JP-A-10-199436 JP 2000-133160 A

  The present invention has been made in view of the above-described problems, and provides a color picture tube that is less likely to cause color purity deterioration due to doming while having a shadow mask with good visibility and excellent moldability and strength. For the purpose.

  The color picture tube of the present invention includes a face panel having an outer surface having a radius of curvature of 10 m or more and having a substantially rectangular phosphor screen formed of a plurality of phosphor rows along the short side direction on the inner surface, and the phosphor screen. And a shadow mask structure opposite to.

  The shadow mask structure is bent with respect to the main surface portion including a substantially rectangular perforated region in which a large number of electron beam passage holes are formed, and a non-perforated region surrounding an outer periphery of the perforated region. A shadow mask having a skirt portion continuously provided on the main surface portion, and a mask frame having a substantially rectangular frame shape that holds the shadow mask by the skirt portion.

The tube axis of the color picture tube is Z-axis, orthogonal to the Z-axis, the axis parallel to the long side of the perforated region is orthogonal to the X-axis, the X-axis and the Z-axis, and the short of the perforated region XYZ Cartesian coordinates where the axis parallel to the side is the Y axis, the point on the X axis that intersects the Z axis is the origin of the X axis, and the point on the Y axis that intersects the Z axis is the origin of the Y axis Define a system, L is the distance along the X axis from the center of the perforated region where the Z axis intersects to the X axis end of the perforated region, the center of the perforated region where the Z axis intersects Is a point P _{(x, y)} on the perforated region where the distance along the Y axis from the perforated region to the Y-axis direction end is S, the X-axis coordinate value is x, and the Y-axis coordinate value is y. When the radius of curvature of the YZ cross section of the shadow mask is Ry _{(x, y)} , the perforated region is
Ry _(0,0) > Ry _{(0, ym1)}
However, 0.4S ≦ ym1 ≦ 0.8S
_Including at least one point P _{(0, ym1)} satisfying
Ry _(xm1,0) <Ry _{(xm1, ym2)}
However, 0.4L ≦ xm1 ≦ 0.8L, 0.4S ≦ ym2 ≦ 0.8S
At least a pair of points P _(xm1,0) and P _{(xm1, ym2) satisfying the above} .

  Since the color picture tube of the present invention is so flat that the outer surface can be called a substantially flat surface, the visibility is good.

  Correspondingly, although the perforated region of the shadow mask has a small drop at the periphery and is substantially flat, the curved mask has a high curved surface holding strength. Therefore, local deformation of the shadow mask during the manufacturing process and operation of the color picture tube is suppressed, and further, color purity deterioration due to doming is small.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  The schematic configuration of the color picture tube according to the present invention is not particularly limited, and may be the same as the conventional color picture tube shown in FIG. 6 except for the shape of a shadow mask, for example.

  FIG. 1 is a perspective view of an embodiment of a shadow mask 4 mounted on a color picture tube according to the present invention. The shadow mask 4 is opposed to the phosphor screen 3 and has a perforated region 41 having a substantially rectangular curved surface in which a large number of electron beam passage holes (not shown) are formed, and a perimeter of the perforated region 41. The main surface part 40 which consists of the hole area | region 42, and the skirt part 43 bent with respect to the main surface part 40 and provided in a row by the main surface part 40 are provided. The shadow mask 4 is integrated with the mask frame 11 by fitting the skirt portion 43 inside the mask frame 11 having a substantially rectangular frame shape and welding the skirt portion 43 and the mask frame 11. Such a shadow mask 4 is formed by press-molding a metal flat plate in which an electron beam passage hole is formed by etching. In FIG. 1, a two-dot chain line 41 a is a long side of the perforated region 41, and a two-dot chain line 41 b is a short side of the perforated region 41.

  The outer surface of the effective portion 1a of the face panel 1 constituting the color picture tube of the present invention is a substantially flat surface having a radius of curvature of 10 m or more in order to improve visibility. Therefore, it is necessary to increase the curvature radius of the inner surface of the effective portion 1a from the viewpoint of the strength and visibility of the envelope 9 with respect to the atmospheric pressure. As the curvature radius of the inner surface of the effective portion 1a is increased, it is necessary to increase the curvature radius of the perforated region 41 of the shadow mask 4 in order to obtain an appropriate electron beam landing. Generally, when the radius of curvature of the perforated region 41 of the shadow mask 4 is increased, as described above, the curved surface holding strength of the perforated region 41 is remarkably reduced, and the resistance to impacts received during the manufacturing process and transportation process of the color picture tube is reduced. This causes problems such as deterioration and vibration characteristics when incorporated in a TV set.

  Based on recent market requirements, it is preferable to use a material containing 95% or more of iron as the material of the shadow mask 4 from the viewpoint of cost.

  However, since such a material has a large coefficient of thermal expansion, local doming occurs when a local high-intensity image pattern as shown in FIG. 7 is displayed, and a local electron beam is generated in a short time. Landing position deviation increases. As a countermeasure, it is conceivable to reduce the radius of curvature of the perforated region 41 of the shadow mask 4 and to reduce the radius of curvature of the inner surface of the effective portion 1a of the face panel 1 as much as possible. However, in this case, the thickness of the periphery of the effective portion 1a of the face panel 1 is increased, so that the face panel 1 is cracked due to thermal stress during the manufacturing process, the luminance is deteriorated around the screen, and the weight is increased. Problems occur.

  The present invention solves such problems.

As shown in FIG. 1, the tube axis of the color picture tube is orthogonal to the Z axis and the Z axis, the axis parallel to the long side 41a of the perforated region 41 is orthogonal to the X axis (long axis), the X axis and the Z axis. The axis parallel to the short side 41b of the perforated region 41 is the Y axis, the point on the X axis that intersects the Z axis is the origin of the X axis, and the point on the Y axis that intersects the Z axis is the origin of the Y axis. Define an XYZ rectangular coordinate system. Further, the distance along the X axis from the center of the perforated region 41 where the Z axis intersects to the end of the perforated region 41 in the X axis direction (that is, the short side 41b) is L, and the perforated region 41 where the Z axis intersects. A distance along the Y axis from the center of the hole region 41 to the end of the perforated region 41 in the Y axis direction (that is, the long side 41a) is S. In addition, a point on the perforated region 41 where the X-axis coordinate value is x (unit: mm) and the Y-axis coordinate value is y (unit: mm) is displayed as P _{(x, y)} . The radius of curvature of the cross section of the perforated region 41 (hereinafter referred to as “YZ cross section”) along the plane parallel to the plane including the Y axis and the Z axis (YZ plane ₎ at the point P _{(x, y)} is Ry _{(x , y)} .

  A point on the perforated region 41 where the Z axis intersects (the center of the shadow mask) is used as a reference point, and the amount of displacement in the Z-axis direction at each point in the perforated region 41 relative to this is referred to as a “sag amount”. The sign of the sagging amount is positive on the electron gun side with respect to the center of the shadow mask. In the present invention, the amount of sagging at each point in the perforated region 41 and the radius of curvature of the YZ cross section are set so that the perforated region 41 has a predetermined aspherical shape.

  FIG. 2 is a plan view showing a ¼ quadrant of the perforated region 41 of the shadow mask 4. Since the curved surface shape of the perforated region 41 is symmetric with respect to the XZ plane (plane including the X axis and the Z axis) and the YZ plane, the curved surface shape in the first quadrant will be described.

In the color picture tube of the present invention, as shown in FIG. 2, two points on the Y axis, that is, the center P _(0,0) and the point P _{(0, ym1)} (provided that 0.4S ≦ ym1 ≦ 0). .8S) when the curvature radii in the YZ section are Ry _(0,0) and Ry _{(0, ym1)} , respectively.
Ry _(0,0) > Ry _{(0, ym1)} (1)
There is at least one point P _{(0, ym1)} that satisfies

Also, the curvature in the YZ section at two points on a straight line parallel to the Y axis, that is, point P _(xm1,0) and point P _{(xm1, ym2)} (where 0.4S ≦ ym2 ≦ 0.8S). When the radii are Ry _(xm1,0) and Ry _{(xm1, ym2)} respectively,
Ry _(xm1,0) <Ry _{(xm1, ym2)} (2)
There are at least a pair of points P _(xm1,0) and P _{(xm1, ym2)} that _{satisfy the above condition in} a range of 0.4L ≦ xm1 ≦ 0.8L.

The presence of the point P _{(0, ym1)} , the point P _(xm1,0) , and the point P _{(xm1, ym2)} as described above is excellent in formability and strength, suppresses doming, and is a substantially flat face panel. A shadow mask suitable for a color picture tube having the above can be realized.

Further, _assuming that the radius of curvature in the YZ section at the end P _{(0, S)} in the Y-axis direction is Ry _{(0, S)} , this and the radius of curvature Ry _{(0, ym1)} at the point P _{(0, ym1).} And
Ry _{(0, ym1)} <Ry _{(0, S)} (3)
Is preferably satisfied. This can prevent an increase in the amount of sagging at the Y-axis end.

Furthermore, YZ at two points on the straight line near the Y axis and parallel to the Y axis, that is, the point P _(xm2,0) and the point P _{(xm2, ym3)} (where 0.4S ≦ ym3 ≦ 0.8S). When the curvature radii in the cross section are Ry _(xm2,0) and Ry _{(xm2, ym3)} , respectively,
Ry _(xm2,0) > Ry _{(xm2, ym3)} (4)
It is preferable that at least a pair of the points P _(xm2,0) and P _{(xm2, ym3) satisfying the above} condition exist within the range of 0 ≦ xm2 ≦ 0.3L. Thereby, the curved surface holding strength of the perforated region 41 of the shadow mask can be further improved.

  The present invention will be described in the case of a color picture tube having a diagonal dimension of 66 cm, an aspect ratio of 16: 9, and an effective radius of the effective portion 1a of the panel 1 of 100 m (hereinafter referred to as “Example 1”).

The outer surface of the effective portion 1a of the face panel 1 of the color picture tube according to the first embodiment is sufficiently flattened as described above, and the shadow mask 4 has a thermal expansion coefficient of 12 × 10 ⁻⁶ at 0 to 100 ° C. It is formed using aluminum killed decarburized steel made of high purity iron.

The dimension of the rectangular perforated region 41 of the shadow mask 4 is such that the distance S from the center P _(0,0) to the end P _{(0, S) in the} Y-axis direction is 153 mm, and the center P _(0,0) to the X axis The distance L to the direction end P _{(L, 0)} was 271 mm.

  Table 1 shows the radii of curvature at main points in the perforated region of the shadow mask of the color picture tube according to Example 1. In addition, Table 1 shows the radii of curvature at main points in the perforated region of the shadow mask of the color picture tube according to Comparative Examples 1a to 1d which are the same as those of Example 1 except that the shape of the shadow mask 4 is different. Show.

As shown in Table 1, in Example 1, the radii of curvature Ry _(0,0) , Ry in the YZ section at two points on the Y axis, that is, the origin P _(0,0) and the point P _{(0,100). (0,100)} satisfies the above formula (1). Further, the curvature radius Ry _{( 200,2)} in the YZ section at two points on the straight line represented by X = 200 [mm] parallel to the Y axis, that is, the point P _(200,0) and the point P _{(200,100) . 0)} and Ry _(200,100) satisfy the above formula (2).

  The curved surface shape (sag amount z) of the perforated region of the shadow mask according to Example 1 and Comparative Examples 1a to 1d is, for example, a general polynomial expression

により表現できる。

Can be expressed by

  In Example 1, the coefficient C (i, j) in the equation (5) is as shown in Table 2.

  In the comparative example 1a, the coefficient C (i, j) of the equation (5) is as shown in Table 3.

  In Comparative Example 1b, the coefficient C (i, j) in the equation (5) is as shown in Table 4.

  In the comparative example 1c, the coefficient C (i, j) of the equation (5) is as shown in Table 5.

  In the comparative example 1d, the coefficient C (i, j) in the equation (5) is as shown in Table 6.

In Table 1, only the radius of curvature at a specific point is shown. However, in the shadow masks according to Comparative Examples 1a to 1d, two points on the Y-axis that satisfy Expression (1), that is, the center P _{(0, 0)} and point P _{(0, ym1)} (provided that 0.4S ≦ ym1 ≦ 0.8S) does not exist, and satisfies the formula (2), within the range of 0.4L ≦ xm1 ≦ 0.8L It was confirmed that there were no two points on the straight line parallel to the Y axis, namely, point P _(xm1,0) and point P _{(xm1, ym2)} (0.4S ≦ ym2 ≦ 0.8S).

In Example 1, the amount of depression at the X-axis direction end P _(271,0) with respect to the center P _(0,0) of the perforated region 41 is about 8 mm, and the amount of depression at the Y-axis direction end P _(0,153) is about The amount of depression at the end P _(271,153) in the diagonal axis direction was 10 mm and 11 mm. In order not to increase the sagging amount in the Y-axis direction end P _(0,153), the radius of curvature Ry _(0,153) in the Y-axis direction end P _(0,153), the points in the intermediate region on the Y-axis at P _{(0, 100) Is} larger than the radius of curvature Ry _(0,100) . That is, the above formula (3) is satisfied. The radius of curvature Ry _(0,153) at the end P _(0,153) in the Y-axis direction in Example 1 was 4161 mm.

  For the shadow masks according to Example 1 and Comparative Examples 1a to 1d, the curved surface holding strength and the amount of beam movement due to doming were measured.

  The curved surface holding strength was evaluated by applying a uniform pressure to the main surface portion 40 of the shadow mask 4, gradually increasing the pressure, and a pressure when a large deformation that causes the perforated region 41 to warp occurred.

  The amount of beam movement due to doming was measured as follows. As shown in FIG. 3, a belt-like pattern 15 parallel to the Y axis having a width W centered on a position separated from the Y axis by a distance D in the center is displayed, and a deviation in the landing position of the electron beam is observed. After waiting for the amount of deviation to saturate, the maximum amount of positional deviation was taken as the amount of beam movement. The distance D = 200 mm, the width W = 110 mm, the anode voltage was 30 kV, and the anode current was 1.35 mA.

  Table 7 shows the measurement results.

  According to the first embodiment, the curved surface holding strength and the beam movement amount can be maintained at high levels.

Next, points P _{(x, 0)} and P _{(x (x )} on the straight line of Y = 0 [mm] (ie, the X axis) and the straight line of Y = 100 [mm], which are separated from the Y axis by x [mm]. _{, 100)} , which is the logarithm of the ratio of the radii of curvature Ry _{(x, 0)} and Ry _{(x, 100)} , is defined as

λ (x) = log {Ry _{(x, 100)} / Ry _{(x, 0)} }

λ (x) can be used as an index indicating the magnitude relationship between the curvature radii Ry _{(x, 0)} and Ry _{(x, 100)} . Table 8 shows the values of λ (x) when x is changed for the shadow masks according to Example 1 and Comparative Examples 1a to 1d.

  Using the data in Table 8, the correlation coefficient r (x) between λ (x) and curved surface retention strength at each x is obtained, and plotted with the horizontal axis as x and the vertical axis as the correlation coefficient r (x). It becomes 4 streets.

As can be seen from FIG. 4, the curved surface holding strength and λ (x) show a high correlation in the region from the Y axis to about 0.3 L in the X axis direction. Therefore, in this region, the value of λ (x) is negative, that is, at least a pair of points P _(xm2,0) and P _{(xm2, ym3)} satisfying the above equation (4) are present in this region. The presence is effective in improving the curved surface holding strength.

  The present invention will be described in the case of a color picture tube having a diagonal dimension of 68 cm, an aspect ratio of 4: 3, and an outer surface radius of the effective portion 1a of the panel 1 of 50 m (hereinafter referred to as “Example 2”).

The outer surface of the effective portion 1a of the face panel 1 of the color picture tube of the second embodiment is sufficiently flattened as in the first embodiment, and the shadow mask 4 has a thermal expansion coefficient of 12 × It is formed using aluminum killed decarburized steel made of 10 ^-6 high purity iron.

The dimension of the rectangular perforated region 41 of the shadow mask 4 is such that the distance S from the center P _(0,0) to the Y-axis direction end P _{(0, S)} is 195 mm, and the center P _{(0,0) is the} X axis. The distance L to the direction end P _{(L, 0)} was 257 mm.

  Table 9 shows the radii of curvature at main points in the perforated region of the shadow mask of the color picture tube according to Example 2. Further, Table 9 shows the radii of curvature at main points in the perforated region of the shadow mask of the color picture tube according to Comparative Examples 2a to 2d which are the same as Example 2 except that the shape of the shadow mask 4 is different. Show.

As shown in Table 9, in Example 2, the radii of curvature Ry _(0,0) , Ry in the YZ section at two points on the Y axis, that is, the origin P _(0,0) and the point P _{(0,120). (0,120)} satisfies the above formula (1). Further, the curvature radius Ry _{(180, 180 )} in the YZ section at two points on the straight line represented by X = 180 [mm] parallel to the Y axis, that is, the point P _(180,0) and the point P _{(180,120) . 0)} and Ry _(180,120) satisfy the above formula (2).

  The curved surface shape (sag amount z) of the perforated region of the shadow mask according to Example 2 and Comparative Examples 2a to 2d is, for example, a general polynomial expression

により表現できる。

Can be expressed by

  In Example 2, the coefficient C (i, j) in the equation (6) is as shown in Table 10.

  In Comparative Example 2a, the coefficient C (i, j) in the equation (6) is as shown in Table 11.

  In Comparative Example 2b, the coefficient C (i, j) in the equation (6) is as shown in Table 12.

  In Comparative Example 2c, the coefficient C (i, j) in the equation (6) is as shown in Table 13.

  In Comparative Example 2d, the coefficient C (i, j) in Expression (6) is as shown in Table 14.

In Table 9, only the radius of curvature at a specific point is shown. However, in the shadow masks according to Comparative Examples 2a to 2d, two points on the Y axis that satisfy Expression (1), that is, the center P _{(0, 0)} and point P _{(0, ym1)} (provided that 0.4S ≦ ym1 ≦ 0.8S) does not exist, and satisfies the formula (2), within the range of 0.4L ≦ xm1 ≦ 0.8L It was confirmed that there were no two points on the straight line parallel to the Y axis, namely, point P _(xm1,0) and point P _{(xm1, ym2)} (0.4S ≦ ym2 ≦ 0.8S).

In Example 2, the sagging amount at the sagging amount in the X-axis direction end P _(257,0) with respect to the center P _(0,0) of the perforated region 41 was about 12 mm, Y-axis direction end P _(0,195) is about The amount of depression at the end P _(257,195) in the diagonal axis direction at 10 mm was about 21 mm. In order not to increase the sagging amount in the Y-axis direction end P _(0,195), the radius of curvature Ry _(0,195) in the Y-axis direction end P _(0,195), the points in the intermediate region on the Y-axis at P _{(0,120) Is} larger than the radius of curvature Ry _(0,120) . That is, the above formula (3) is satisfied. In Example 2, the radius of curvature Ry _(0,195) at the end P _(0,195) in the Y-axis direction was 3047 mm.

  For the shadow masks according to Example 2 and Comparative Examples 2a to 2d, the curved surface holding strength and the amount of beam movement due to doming were measured.

  The method of measuring the curved surface holding strength is the same as in the case of Example 1 above. The method of measuring the beam movement amount by doming is the same as in the case of Example 1 except that the distance D = 185 mm, the width W = 100 mm, the anode voltage is 30 kV, and the anode current is 1.52 mA.

  Table 15 shows the measurement results.

  According to the second embodiment, the curved surface holding strength and the beam movement amount can be maintained at a high level.

Next, points P _{(x, 0)} and P _{(x (x )} separated from the Y axis by x [mm] on the straight line Y = 0 [mm] (that is, the X axis) and the straight line Y = 120 [mm]. _{, 120)} , which is the logarithm of the ratio of the radius of curvature Ry _{(x, 0)} and Ry, λ (x) expressed by the following equation is defined.

λ (x) = log {Ry _{(x, 120)} / Ry _{(x, 0)} }

λ (x) can be used as an index indicating the magnitude relationship between the curvature radii Ry _{(x, 0)} and Ry _{(x, 120)} . Table 16 shows the values of λ (x) when x is changed for the shadow masks according to Example 2 and Comparative Examples 2a to 2d.

  Using the data in Table 16, the correlation coefficient r (x) between λ (x) and curved surface retention strength at each x is obtained, and plotted with the horizontal axis as x and the vertical axis as the correlation coefficient r (x). It becomes 5 streets.

As can be seen from FIG. 5, the curved surface holding strength and λ (x) show a high correlation in the region from the Y axis to about 0.3 L in the X axis direction. Therefore, in this region, the value of λ (x) is negative, that is, at least a pair of points P _(xm2,0) and P _{(xm2, ym3)} satisfying the above equation (4) are present in this region. The presence is effective in improving the curved surface holding strength.

Since the electron beam landing on the Y-axis is not deflected in the X-axis direction, even if doming occurs, the color purity does not deteriorate on the Y-axis. As the distance from the Y-axis increases, the X-axis direction component of the deflection angle increases, so the degree of color purity deterioration increases. The region where doming is increased is a region of 0.4L ≦ x ≦ 0.8L, and is particularly large at a point on the X axis where x = (2/3) × L as described above. Therefore, in the region of x> 0.3 L where the influence on the curved surface holding strength is low,
Ry _(xm3,0) <Ry _{(xm3, ym4)}
However, xm3> 0.3L, 0.4S ≦ ym4 ≦ 0.8S
The point P _(xm3,0) and the point P _{(xm3, ym4) satisfying the above-mentioned condition} is that the point on the X axis where x = (2/3) × L, where doming tends to be particularly large This is preferable in order to reduce the radius of curvature.

  The color picture tube according to the present invention is excellent in visibility because the outer surface of the face panel is almost flat, and color misregistration due to doming can be reduced even if a shadow mask made of iron is used for cost reduction. Therefore, it can be widely used as a color picture tube capable of performing good color display.

The perspective view of one Embodiment of the shadow mask mounted in the color picture tube which concerns on this invention The top view which showed the position of the point in the 1st quadrant of the perforated area | region of the shadow mask used for the color picture tube of this invention Front view showing an example of an image pattern when measuring a beam movement amount due to doming The figure which shows the correlation curve of curvature-radius ratio (lambda) (x) and curved surface holding | maintenance intensity | strength about the shadow mask for color picture tubes with a diagonal dimension of 66 cm. The figure which shows the correlation curve of curvature-radius ratio (lambda) (x) and curved surface holding | maintenance intensity | strength about the shadow mask for color picture tubes with a diagonal dimension of 68 cm. Sectional drawing which showed schematic structure of an example of a color picture tube Front view showing an example of a position where local doming occurs in the shadow mask

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Face panel 1a Effective part 1b Skirt part 2 Funnel 2a Neck 3 Phosphor screen 4 Shadow mask 40 Main surface part 41 Perforated area 41a Perforated area long side 41b Perforated area short side 42 Non-perforated area 43 Skirt part 5 Shadow Mask structure 6B, 6G, 6R Electron beam 7 Electron gun 8 Deflector 9 Envelope 10 Internal magnetic shield 11 Mask frame

Claims (4)

A face panel having an outer surface having a radius of curvature of 10 m or more and a substantially rectangular phosphor screen formed of a plurality of phosphor rows along the short side direction on the inner surface;
A color picture tube comprising a shadow mask structure facing the phosphor screen,
The shadow mask structure is
A main surface portion consisting of a substantially rectangular perforated region in which a large number of electron beam passage holes are formed, a non-porous region surrounding the outer periphery of the perforated region, and a bent portion connected to the main surface portion. A shadow mask having a skirt portion provided;
A mask frame having a substantially rectangular frame shape that holds the shadow mask at the skirt portion;
The tube axis of the color picture tube is Z-axis, orthogonal to the Z-axis, the axis parallel to the long side of the perforated region is orthogonal to the X-axis, the X-axis and the Z-axis, and the short of the perforated region XYZ Cartesian coordinates where the axis parallel to the side is the Y axis, the point on the X axis that intersects the Z axis is the origin of the X axis, and the point on the Y axis that intersects the Z axis is the origin of the Y axis Define the system,
The distance along the X axis from the center of the perforated region where the Z axis intersects to the X axis direction end of the perforated region is L,
A distance along the Y axis from the center of the perforated region where the Z axis intersects to the Y axis direction end of the perforated region, S,
When the radius of curvature of the YZ cross section of the shadow mask at the point P _{(x, y)} on the perforated region where the X-axis coordinate value is x and the Y-axis coordinate value is y is Ry _{(x, y)} ,
The perforated region is
Ry _(0,0) > Ry _{(0, ym1)}
However, 0.4S ≦ ym1 ≦ 0.8S
_Including at least one point P _{(0, ym1)} satisfying
Ry _(xm1,0) <Ry _{(xm1, ym2)}
However, 0.4L ≦ xm1 ≦ 0.8L, 0.4S ≦ ym2 ≦ 0.8S
A color picture tube comprising at least a pair of points P _(xm1,0) and P _{(xm1, ym2) satisfying the above} .   The color picture tube according to claim 1, wherein the shadow mask is made of a material containing 95% or more of iron. The point P curvature at _{(0, ym1)} radius Ry _{(0, ym1)} is _{Ry (0, ym1) <Ry} (0, S)
The color picture tube according to claim 1, which satisfies the following conditions. The perforated region further includes
Ry _(xm2,0) > Ry _{(xm2, ym3)}
However, 0 ≦ xm2 ≦ 0.3L, 0.4S ≦ ym3 ≦ 0.8S
2. The color picture tube according to claim 1, comprising at least a pair of a point P _(xm2,0) and a point P _{(xm2, ym3) satisfying the above} .

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