KR100524861B1 - Mask frame for cathode ray tube - Google Patents

Abstract

The present invention relates to a mask frame for a cathode ray tube, and in particular, when the screen width is increased in order to prevent a decrease in luminance due to a decrease in glass transmittance when a tint panel is applied, the purity margin is reduced due to the influence of a geomagnetic field when the direction is changed. In order to improve this, the height of the diagonal end of the mask frame is higher than that of the prior art, thereby reducing the amount of electron beam movement due to the geomagnetic field, thereby increasing the purity margin at the time of changing the direction, and also preventing the improvement of luminance deterioration caused by panel tinting. Even if the screen phosphor width is increased, it is possible to prevent color purity defects by reducing the amount of beam movement due to the change of the magnetic field.

Description

Mask frame for cathode ray tube {MASK FRAME FOR CATHODE RAY TUBE}

The present invention relates to a mask frame for a cathode ray tube, and in particular, in the case of increasing the screen width in order to prevent a decrease in brightness due to a decrease in glass transmittance when applying a tint panel, a decrease in purity margin due to the influence of a geomagnetic field during the change of direction. The present invention relates to a mask frame for a cathode ray tube, in which a height of a diagonal axis end of the mask frame is made higher than in the prior art, thereby reducing the amount of electron beam movement caused by the geomagnetic field, thereby increasing the purity margin at the time of change of direction.

In general, as shown in FIG. 1, the color cathode ray tube is sealed by a high vacuum by combining a front glass called the panel 3 and a rear glass called the funnel 4.

In the interior space, a phosphor screen 1 applied to the inner surface of the panel 3 to serve as a predetermined light emitter, and electron beams 11R, 11G and 11B for emitting the phosphor screen 1 are provided. A shadow mask 5 for selecting the emitted electron gun 9 and the electron beams 11R, 11G and 11B generated by the electron gun 9 to be seated on a predetermined portion of the phosphor screen 1; A mask frame 7 for fixing / supporting the shadow mask 5, an elastic support 23 and a stud pin 2 for coupling the mask frame 7 assembly to the panel 3, and the funnel An electron gun 9 mounted on the inner side of the neck portion 8 side of (4) to generate the electron beams 11R, 11G and 11B, and an electron beam 11R and 11G generated by the electron gun 9. ) And a deflection yoke 10 for deflecting 11B in a predetermined direction.

The three-color electron beams 11R, 11G and 11B emitted from the electron gun 9 are deflected by a deflection yoke 10 mounted on the outside of the funnel 4 and penetrates the shadow mask 5 so as to pass through the shadow mask 5. It is configured to reach each of the three-color phosphors 1R (1G) 1B applied to the phosphor screen 1.

2 shows a three-color electron beam 11R, 11G, 11B emitted from an electron gun 9 passing through an electron beam passing hole 12 formed in the main surface 22 of the shadow mask 5 so that the phosphor screen 1 Is a schematic perspective view showing a process of reaching the three-color phosphor (1R) (1G) (1B).

The shadow mask 5 is formed of a curved surface having a shape corresponding to the shape of the phosphor screen 1, and includes a main surface 22 having a plurality of electron beam through holes 12 formed therein, and a peripheral portion of the main surface 22. The skirt portion 6 is bent in the vertical direction.

In the shadow mask 5, the skirt part 6 is welded to the mask frame 7, and an elastic support 23 coupled to the mask frame 7 is provided inside the panel 3. It is supported inside the panel 3 by being coupled to the installed stud pins 2.

FIG. 4A is a plan view showing a state in which the shadow mask 5 and the mask frame 7 are coupled, and FIG. 4B shows a plurality of surfaces on the main surface 22 in which the shadow mask 5 is curved to face the phosphor screen 1. It is sectional drawing which showed the spherical mask frame 7 in which the electron beam passage hole 12 was provided, and the skirt part 6 of the mask contacted and welded to the side wall part 13 of the said mask frame 7.

5A, 5B, and 5C, the mask frame 7 is formed upright along the tube axis (Z axis), and the skirt portion 6 of the shadow mask 5 is in contact with and welded to the mask frame 7. It is formed to have a side wall portion 13.

A portion of the electron beams 11R, 11G, 11B emitted from the electron gun 9 reach the screen phosphor 1 through the shadow mask hole 12, but most of the electron beams 11R, 11G ( 11B) impinges on the shadow mask 5.

Thus, the shadow mask 5 itself generates heat, and the heat of the heated shadow mask 5 is transmitted to the mask frame 7 which is in contact with the mask, and to the mask frame 7. The heat is transferred to the elastic support 23 and the stud pin 2 coupled to the mask frame 7 to release the heat generated by the shadow mask 5 to the outside of the cathode ray tube. The deposition performance of the electron beam is reduced by the expansion of 5), and the color purity deterioration is prevented from occurring.

In addition, the mask frame 7 is coupled to the mask skirt 6 to fix the shadow mask 5 as well as the heat transfer function described above, and prevents deformation of the shadow mask 5 due to external impact. do.

On the other hand, when the radius of curvature of the outer surface of the panel 3 is infinite or almost flat, the inner radius of curvature of the panel 3 is smaller than the outer curvature.

In addition, the curvature Rd (Rh) (Rv) of the shadow mask 5 formed according to the radius of curvature of the inner surface of the panel 3 may increase the mechanical strength of the shadow mask 5. It should be equal to or smaller than the inner surface curvature Rd '(Rh') (Rv '), and make the radius of curvature Rh of the major axis smaller than the minor axis radius of curvature Rv, and the radius of curvature Rv of the minor axis direction. It is known that reducing the diagonal radius of curvature Rd is effective in increasing the mechanical strength of the mask.

The height h (v) (d) of the long axis end Th, the short axis end Tv, and the diagonal axis end Td of the mask frame 7 has its curvature ( Rh) (Rv) (Rd) is brought about equal to the inner curvature Rh '(Rv') (Rd ') of the panel 3, so that the height v of the short end of the mask frame 7 is The height h of the long shaft end and the height d of the diagonal shaft end are higher, and the height d of the diagonal shaft end is the lowest.

On the other hand, the panel 3 of the color cathode ray tube of which the radius of curvature of the outer surface of the panel 3 is infinite or almost flat prevents the deterioration of the contrast quality due to external reflection and increases the color purity of the phosphor screen 1. Apply the coating to the surface.

However, a certain amount of coating liquid is injected into the center of the outer surface of the panel 3 and the panel 3 is rotated so that the coating liquid is applied to the front surface of the panel. Not only makes it uneven, but also generates many defects.

In addition, after the coating is passed through a kiln to increase the film strength, it is difficult to obtain the strength as much as the desired film strength, and there is a problem in that an expensive coating liquid must be used to increase the film strength.

In order to improve this problem, the panel 3 can be tinted (light transmittance of 51%), thereby eliminating the use of the coating solution, thereby reducing the material cost, and reducing the defect rate due to poor coating, thereby improving productivity.

However, when the panel 3 is tinted, the light transmittance drops sharply toward the periphery of the panel 3.

The reason is that, as shown in FIG. 7, for example, the center thickness 16 (Tc) of the panel 3 is 12.5 mm and the wedge thickness 14 (Tco) of the panel 3 is the panel ( The coating liquid is applied to the outer surface of the panel 3 when the width of the phosphor screen 1 at the periphery is 185 μm, which is 220% larger than the center thickness 16 (Tc) of 3) and the width of the phosphor screen 1 is 185 μm. In this case, the light transmittance at the center of the panel 3 is 54.41%, the light transmittance at the periphery of the panel 3 is about 46.5%, and a light transmittance decrease of about 5% occurs at the periphery of the panel 3.

However, when the panel 3 is tinted, the light transmittance of the panel center portion 16 (Tc) is 51.15% due to the difference between the panel center portion and the wedge portion thickness 16 (Tc) 14 (Tco). The light transmittance of the wedge portion 14 (Tco) is almost the same as that of the coated product, but the light transmittance of the wedge portion 14 (Tco) is lower than that of the coating of the surface of the panel 3 by 25.56%. Since the 45% fall, the brightness of the wedge portion 14 (Tco) is lowered and the corner brightness is lowered by about 15 fl than when the panel 3 is coated.

Therefore, the wedge portion B / U value, which is an index of color purity uniformity of the color cathode ray tube screen, is lowered (see Table 2).

Therefore, in order to increase the brightness of the wedge portion 14 (Tco) of the panel 3, the phosphor screen width Bd of the wedge portion 14 (Tco) must be increased by about 24% from the present (see Table 3).

However, if the phosphor screen width Gs shown in Fig. 3 is increased, the purity of the electron beams 11R, 11G, and 11B will cause the phosphors 1R, 1G, and 1B to emit light when the geomagnetic field and the direction change. The margin (see FIG. 3) is reduced, resulting in poor color purity of the color cathode ray tube.

In addition, although the light transmittance decrease can be improved by reducing the thickness of the wedge portion of the inner surface of the panel 3, the curvature Rd (Rv) (Rh) of the shadow mask 5 is the curvature Rd 'of the inner surface of the panel. Since it must go similarly to (Rv ') (Rh'), when the curvature of the inner surface of the panel increases, the curvature of the mask main surface 22 increases, which causes mask deformation during impact, and causes the mechanical strength to be degraded by the howling to reduce color purity. Will have

panel Center thickness Wedge thickness Perimeter phosphor screen width size 12.5 mm 27.5 mm 185 ㎛

Tinted Panel Center phosphor screen width Corner phosphor screen width Direction margin B / U 170 μm 185 ㎛ 25 degrees 50 fl 160 ㎛ 230 ㎛ 18 degrees 50 fl

panel Center light transmittance Corner light transmittance Peripheral B / U coating 54.41% 46.51% 50 fl Tint 51.15% 25.56% 35 fl

In other words, when tinting in the panel 3 of the color cathode ray tube with an infinite curvature radius of the outer surface of the panel 3 is almost infinite, the thickness of the center portion 16 (Tc) of the panel 3 and the wedge portion thickness ( 14) Due to the difference in Tco, the light transmittance of the wedge portion 14 (Tco) is reduced by about 20% compared to when the panel 3 is coated, so that the difference in luminance of the wedge portion is reduced by about 15 fl from the center of the screen. Since the size of the wedge portion phosphor screen width Gs of the panel 3 must be increased by 24% to improve the width, the width of the black stripe Bd decreases inversely.

Therefore, when the width of the black stripe Bd is reduced because the electron beams 11R, 11G, and 11B move about 35 μm when changing the geomagnetic field and direction, as shown in FIG. 3, the purity of the electron beam landings. The margin decreases, and color shifting tends to occur.

Therefore, in order to cope with this, the amount of movement of the moving electron beam in the geomagnetic field and the direction change must be reduced.

In general, in order to reduce the amount of movement of the electron beam, the inner shield (not shown) is changed to reduce the amount of movement of the electron beam, or the shape of the inner shield (not shown) is used to reduce the amount of electron beam movement.

However, when the material is changed, the unit cost increases, and when the inner shield shape is changed, it is not easy to reduce the absolute amount of the electron beam.

Meanwhile, as shown in FIGS. 7 and 8, the conventional cathode ray tube is inner when the electron beams 11R, 11G, and 11B pass through the panel 3 by the deflection magnetic field when the geomagnetic field changes and changes direction. The shield 15 reduces the influence of the electron beam due to the geomagnetic field, but in the case of the electron beam 30 passing through the electron beam passing hole 12 formed in the main surface 22 of the shadow mask 3, it is completely exposed to the magnetic field. The larger the distance 17 between the center of the panel 3 and the mask center C and the distance 18 between the diagonal axis end of the mask frame 5 and the inner surface of the panel, the larger the electron beams 11R, 11G, and 11B. ) Is sensitive to the magnetic field and the deflection amount increases.

Reference numeral 19 is a distance from the diagonal axis end of the mask frame 5 to the screen.

SUMMARY OF THE INVENTION An object of the present invention devised in view of the above is to provide a mask frame for a cathode ray tube that increases the height of the diagonal axis end of the mask frame higher than conventionally, thereby reducing the amount of electron beam movement caused by the geomagnetic field, thereby increasing the purity margin upon redirection. It's there.

In order to achieve the object of the present invention as described above, the outer radius of the curvature of the panel is infinite or almost flat, the funnel mounted on the back of the panel, and the plurality of electron beams arranged at regular intervals on the inner surface of the panel passing A color cathode ray tube comprising a shadow mask having a hole and a mask frame for supporting the shadow mask, wherein the diagonal height of the mask frame is d, the height of the major axis end is h, and the height of the minor axis is v. A color cathode ray tube is provided, which satisfies the following expressions d / v ≧ 0.9 and d / h ≧ 0.9.

In addition, in order to achieve the object of the present invention, a panel having an infinite curvature radius of its outer surface or almost flat, a funnel mounted on the back of the panel, and a plurality of electron beam through holes disposed at regular intervals on the inner surface of the panel. In a color cathode ray tube including a shadow mask provided and a mask frame for supporting the shadow mask, when the height of the diagonal portion of the mask frame is d, the height of the major axis end is h, and the height of the minor axis is v, A color cathode ray tube is provided, which satisfies d≥h and d≥v.

Hereinafter, the color cathode ray tube of the present invention will be described in detail based on the accompanying drawings.

In general, the thickness of the panel 3 of the color cathode ray tube in which the outer surface curvature is infinite or almost flat in the panel 3 is shorter than the central portion of the panel 3 in consideration of the explosion-proof characteristic (Tv), as shown in FIG. 9. ), The long axis Th, and the diagonal axis Td.

Therefore, as shown in FIG. 10, the inner surface of the panel 3 has a short axis radius of curvature Rv 'greater than the long axis radius of curvature Rh', and the long axis radius of curvature Rh 'is a diagonal radius of curvature Rd'. Greater than)

In general, the main surface 22 of the main body of the shadow mask 5 facing the phosphor screen 1 is formed along the curvature of the inner surface of the panel 3, but in order to increase the mask strength in response to external impact, the panel ( 3) The curvature Rd (Rv) (Rh) of the major axis, short axis and diagonal axis of the main surface 22 of the shadow mask 5 main body is smaller than the internal curvature Rd '(Rv') (Rh '). It is known to be good.

In particular, the mask diagonal radius of curvature Rd is preferably smaller than the inner curvature Rd 'of the panel 3.

Therefore, as shown in FIG. 11, the curvature of the shadow mask 5 at the center of the inner surface of the panel 3 forms a curve of Rd in the diagonal direction from the mask center C, the size of which is Rd1, and the curvature of Rh in the major axis direction. The size is Rh1, the curvature of Rv in the short axis direction, and the size is Rv1.

The height of the diagonal axis end of the side wall portion 13 of the mask frame 7 corresponding to the above is d, the height of the major axis is h, and the height of the short axis is v.

12 and 13, the diagonal axis end gap 18 (Dd) between the inner surface of the panel 3 and the mask frame 7 is larger than the gap Dh of the major axis end and the distance Dv of the short axis end. As shown in FIG. 13, the electron beam is deflected by the deflection yoke at the deflection center 20 and passes through the mask hole 12 of the diagonal axis of the panel 3 so as to have a constant distance 19 from the diagonal axis end of the mask frame 70. Since the screen reaches the phosphor screen inside the panel, it is possible to increase the height d of the frame diagonal axis end as shown in FIG.

Frame (d) Electron beam shift amount (㎛) 5 degrees 10 degree 15 degrees 20 degrees 25 degrees 55 mm 15 20 25 30 35 58 mm 14 18.5 23 27.5 34 61 mm 13.8 17 22.5 26 33.5 64 mm 13 16.5 21 25.2 33 67 mm 12.7 15.8 20.7 24.2 32.2 70 mm 12 15 20.2 24 29 73 mm 11.9 14.8 19.8 23.2 28

Through the above experiment, it can be seen that the effect is obtained when the height d of the diagonal axis of the mask frame 7 satisfies the height h of the major axis and the height v of the short axis.

That is, as shown in Table 4, if the distance between the wedge portion of the panel 3 and the mask frame 70 is reduced, it can be seen that the amount of movement of the electron beam due to the change of the magnetic field during the direction change.

This can be summarized as follows.

d / v ≥ 0.9, d / h ≥ 0.9 ---------------------------- (1)

More preferably, the following equation is satisfied as shown in FIG. 15 in consideration of design characteristics of the color cathode ray tube manufactured in the field.

d≥h, d≥v ---------------------------------------- (2)

15 is a perspective view showing a mask frame 70 for a cathode ray tube of the present invention, Figure 15 is a height (d) of the diagonal axis end has a shape higher than the height (h) of the long axis end and the height (v) of the short axis end. It is present.

In the above formula (1), the relationship between the height h of the long axis end and the height v of the short axis end may satisfy either the following formula (3) or formula (4).

v ≥ h ------------------------------------------- (3)

h ≥ v ------------------------------------------- (4)

16 and 17 are side views illustrating the shape of the side portions of the long side axis and the short side axis of the mask frame 70. As shown in FIGS. 16 and 17, the shape of the side cross-sections of the long side axis and the short side axis of the mask frame 70 is formed symmetrically with respect to the center thereof, and the shape of the side portion thereof based on the center thereof is left / right. It has at least one inflection point (IP) on its right side, and the shape of half of its side is formed such that its height gradually decreases from the side end to its center and then increases.

In FIG. 16, when the length of half of the long axis is L, the position IP of the inflection point is located at a location L / 2 ≦ IP ≦ 4L / 5 from the center of the long axis. At this time, the position of the IP is to exist at a position corresponding to about 63.5% of the length L in the direction of the side end portion from the center of the long axis as an embodiment.

Also in FIG. 17, when the length of half of the short axis is S, the position IP of the inflection point is located at a position S / 2 ≦ IP ≦ 4S / 5 from the center of the short axis to the side end portion. At this time, the position of the IP is located at a position corresponding to about 52.5% of the length L in the direction of the side end portion from the center of the short axis as an embodiment.

On the other hand, the inventor of the present invention proposed the following formula (5) in the range of the formula (1) in consideration of the effects of ease of production process and yield improvement.

0.9 ≤ d / v ≤ 1.15, 0.95 ≤ d / h ≤ 1.2 -------------- (5)

That is, by forming the mask frame 70 as the long and short axis of the shape as described above, it is possible to reduce the weight of the mask frame 70, the mask frame 70 for generating thermal deformation due to the decrease in the volume As the volume decreases, the performance of coping with the doming phenomenon is improved, and the weight thereof decreases, and thus the weight thereof is reduced, which is advantageous in the drop performance test.

One embodiment of the present invention as described above is shown in FIG. FIG. 18 shows a tinted panel 3 having a center thickness of 12.5 mm and a diagonal wedge portion of 24.25 mm.

In FIG. 18, the height Rd is 22.2 mm in the direction of the tube axis (Z axis) from the diagonal portion Rd of the main surface 22 with respect to the mask center C at the center of the inner surface of the panel 3, and the mask frame 7. In the case where the height of the diagonal end of the diagonal portion is 54.8 mm, the distance between the inner surface of the wedge portion of the panel 3 and the diagonal axis end connecting portion 24 of the mask frame 7 is 25.95 mm, so that the height of the mask frame 7 It is possible to increase the diagonal shaft end height from the current 54.8mm to 80.75mm.

However, in the cathode ray tube, since the electron beam 21 is deflected by the deflection coil 10 with a certain deflection angle, the height of the diagonal shaft end of the frame is increased as shown in FIG. 19 to prevent the electron beam interference by the mask frame 7. It is preferable to raise only 17mm.

According to the present invention, the electron beam generated by the magnetic field exposure before the electron beam passing through the mask, which is generated due to the large gap between the panel and the mask frame, reaches the screen phosphor effective portion inside the panel, without changing the material or the shape of the inner shield. By making the height d of the diagonal axis end portion of the mask frame higher than the height of the major axis h and the minor axis v, as shown in FIG. 15, that is, the height of the major axis h and the height of the minor axis of the mask frame are shown. (v) When the lower diagonal shaft end height d is 17 mm higher than the major and short axis heights, the amount of electron beam movement can be reduced by 6 µm or more to improve the directional margin by about 7 degrees (see Table 5).

In addition, even if the screen phosphor width is increased to prevent improvement in luminance caused by panel tinting, the color shift can be prevented by reducing the amount of beam movement caused by the magnetic field change.

panel Center / Ambient Light Transmittance (%) d (mm) Center / Peripheral Gs (㎛) Electron beam shift amount (㎛) Directional degree of freedom (degrees) Panel coating 54.41 / 46.51 54.8 170/185 35 25 Panel Tint 51.15 / 25.56 54.8 160/230 35 18 Panel Tint 51.15 / 25.56 71.8 160/230 29 25

1 is a cross-sectional view showing the configuration of a conventional cathode ray tube.

2 is a schematic perspective view showing that an electron beam emitted from an electron gun of a conventional cathode ray tube passes through a mask and reaches a phosphor screen.

Figure 3 is a schematic diagram showing the electron beam is seated on the fluorescent surface in the conventional cathode ray tube and thus the purity margin.

4A is a plan view illustrating a state in which a shadow mask and a mask frame of a conventional cathode ray tube are coupled.

4B is a cross sectional view of FIG. 4A.

Fig. 5A is a plan view showing the structure of a mask frame of a conventional cathode ray tube.

5B is a longitudinal cross-sectional view of FIG. 5A.

5C is a cross-sectional view of FIG. 5A.

6 is a graph showing the difference between the major axis (X), minor axis (Y) and diagonal portion height of the mask frame of the cathode ray tube.

7 is a schematic diagram illustrating a process of electron beam deflecting at the center of deflection and passing through a shadow mask to a phosphor screen of a panel in a conventional cathode ray tube.

8 is a schematic diagram showing a moving direction of an electron beam by a geomagnetic field in a conventional cathode ray tube.

9 is a graph showing thicknesses of the long axis X, the short axis Y, and the diagonal portion of a panel of a conventional cathode ray tube.

10 is a schematic diagram showing the difference between the inner curvature of the long axis (X), the short axis (Y) and the diagonal portion of the panel in the conventional cathode ray tube and the principal surface curvature of the shadow mask.

11 is a graph showing the major axis (X), minor axis (Y) and diagonal axis end height of the mask frame according to the curvature of the main surface of the shadow mask in the conventional cathode ray tube.

12 is a graph showing the difference between the panel and the mask frame in the long axis (X), short axis (Y) and the diagonal portion of the panel in the conventional cathode ray tube.

13 is an exemplary view showing that the height of the diagonal shaft end portion of the mask frame of the cathode ray tube of the present invention can be increased.

14 is a graph showing the major axis (X), minor axis (Y) and diagonal axis end height of the mask frame according to the curvature of the mask main surface of the present invention.

15 is a perspective view showing a mask frame of a cathode ray tube to which the present invention is applied.

FIG. 16 is a side view illustrating the shape of a side portion of the long axis of the mask frame of FIG. 15. FIG.

FIG. 17 is a side view illustrating the shape of a side portion of the short axis of the mask frame of FIG. 15. FIG.

18 is a schematic cross-sectional view showing a mask frame of a cathode ray tube to which the present invention is applied.

19 is a graph showing the reason why the height of the diagonal shaft end portion of the mask frame of FIG. 15 is limited to 17 mm.

(Explanation of symbols for the main parts of the drawing)

1: phosphor screen 3: panel

4: funnel 5: shadow mask

70: mask frame d: diagonal height of the mask frame

h: height of major axis of mask frame

v: height of short end of mask frame

Claims (22)

A shadow mask having a panel having an infinite radius of curvature on its outer surface or almost flat, a funnel mounted on the rear of the panel, a plurality of electron beam through holes arranged at regular intervals on the inner surface of the panel, and a shadow mask In the color cathode ray tube comprising a mask frame, A color cathode ray tube satisfying the following expression when the height of the diagonal portion of the mask frame is d, the height of the major axis end is h, and the height of the minor axis is v. d / v ≥ 0.9, d / h ≥ 0.9 The color cathode ray tube according to claim 1, wherein d / v and d / h satisfy the following equation. 0.9 ≤ d / v ≤ 1.15, 0.95 ≤ d / h ≤ 1.2 The color cathode ray tube according to claim 1, wherein when the half length of the long axis is L, the position IP of the inflection point formed on the long axis is within L / 2 to 4L / 5. (Where L / 2 is the distance L / 2 away from the center of the long axis and 4L / 5 is 4L / 5 away from the center of the long axis). The color cathode ray tube according to claim 1, wherein when the height of the diagonal portion of the mask frame is d, the height of the major axis end is h, and the height of the minor axis is v, the following formula is satisfied. d / v ≥ 1.0, d / h ≥ 1.0 The color cathode ray tube according to claim 1, wherein when half of the short axis length is S, the position IP of the inflection point formed on the short axis axis is present within S / 2 to 4S / 5. (Where S / 2 is the distance S / 2 away from the center of the long axis and 4S / 5 is 4S / 5 away from the center of the long axis). According to claim 1, wherein the shape of the side portion of the long side axis forming the mask frame has at least one or more inflection points on the left and right, the height is reduced to increase from the side end portion to the center thereof, When the half length of the long axis is L, the color IP of the inflection point formed on the long axis is within L / 2 to 4L / 5. (Where L / 2 is the distance L / 2 away from the center of the long axis and 4L / 5 is 4L / 5 away from the center of the long axis) delete According to claim 1, wherein the side shape of the short axis forming the mask frame has at least one or more inflection points on the left and right, the height is reduced to increase from the side end to its center and formed to increase, When the half of the short axis length is S, the position IP of the inflection point formed on the short axis is a color cathode ray tube, characterized in that present in S / 2 to 4S / 5. (Wherein S / 2 is a distance S / 2 away from the center of the long axis and 4S / 5 is 4S / 5 away from the center of the long axis). Color cathode ray tube. delete delete delete The color cathode ray tube according to claim 1, wherein the following formula is satisfied when the light transmittance of the center portion of the panel is Tc. Tc ≤ 54% The color cathode ray tube according to claim 1, wherein when the light transmittance of the panel wedge portion is Tco, the following formula is satisfied. Tco ≤ 26% The color cathode ray tube according to claim 1, wherein the thickness of the center portion of the panel satisfies the following equation. Pc ≤ 13.5 mm The color cathode ray tube according to claim 1, wherein the thickness at the center of the panel is Tc and the thickness at the panel periphery is Tco. Tco / Tc <2.4 delete delete delete delete delete delete delete