JP3144845B2 - Color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to a color picture tube capable of shielding terrestrial magnetism and obtaining a good landing.

[0002]

2. Description of the Related Art Generally, a color picture tube has an envelope comprising a substantially rectangular panel 1 and a funnel-like funnel 2 integrally joined to the panel 1, as shown in FIG. A phosphor screen 3 made of a three-color phosphor layer that emits blue, green and red light is formed on one inner surface, and a substantially rectangular shadow mask 4 is disposed inside and close to the phosphor screen 3. ing. The shadow mask 4 has a substantially rectangular mask body 6 in which a skirt portion 5 is formed on the outer periphery of an effective portion in which a large number of electron beam passage holes are formed, and a mask having the skirt portion 5 of the mask body 6 inside. An L-shaped cross-section mask frame 8 having a side wall 7 parallel to the tube axis (z-axis) is attached to the main body 6. In the neck 9 of the funnel 2, three electron beams 10
An electron gun 11 for emitting electrons is arranged. Then, the three electron beams 10 emitted from the electron gun 11 are deflected by a magnetic field generated by a deflection yoke 12 mounted on the outside of the funnel 2 to move the phosphor screen 3 horizontally and vertically through the shadow mask 4. The phosphor screen 3 is formed into a structure for displaying a color image by scanning.

In order to correctly display an image on the phosphor screen 3, the phosphor screen 3 and the shadow mask 4 must be arranged in a matching relationship. When affected by the external magnetic field, the electron beam 10
Trajectory changes, there is the color purity deviates landing is deteriorated for three-color phosphor layers. For this reason, conventionally, a color picture tube has an internal magnetic shield 14 made of a magnetic material attached to the mask frame 8 of the shadow mask 4 and is disposed inside the funnel 2 so that the inside of the funnel 2 which is most susceptible to an external magnetic field is provided. It shields the electron beam passage area.

As the most basic structure of the internal magnetic shield 14, as shown in FIG. 7, a mild steel plate having a thickness of about 0.1 to 0.3 mm is formed into a square trapezoidal shape. However, with this structure, the shielding effect is not sufficient, and good landing may not be obtained.

For simplicity of explanation, a color picture tube in which a three-color phosphor layer constituting a phosphor screen is made up of vertically elongated stripes has a magnetic shield 14 inside.
In the color picture tube, even if the landing of the electron beam is shifted in the vertical direction, the phosphor layer of the same color lands, and the color purity does not deteriorate. Therefore, the landing shift does not pose a problem. However, horizontal landing deviation degrades color purity.

Now, the pipe axis is Z, the horizontal axis is X, the vertical axis is Y,
Assuming that the magnetic flux density is B and the velocity of the electron beam is v, the magnetic field affecting the horizontal landing is a vertical axis component By and a tube axis component Bz, and these magnetic field components By and Bz are The tube axis velocity component vz and the vertical axis velocity component vy act to cause a landing deviation. 8 (a) is Lundin with the tube axis direction component Bz
Shows a grayed deviation by arrows 16a, not a the landing <br/> Re is, in fact, the electronic accompanying geomagnetic in the tube axis direction component Bz and vertical deflection of the case of installing a color picture tube northward beam Is a landing deviation due to the vertical velocity component vy. When the color picture tube is installed facing south, a landing displacement occurs in the direction opposite to the arrow 16a shown in FIG. FIG. 8B shows a vertical axis direction component By.
Shows the landing deviation by an arrow 16b, this landing deviation is a landing deviation by the tube axis direction velocity component vz of the geomagnetic a vertical axis direction component By and the electron beam in the northern hemisphere.

In the above-mentioned internal magnetic shield, a leakage magnetic field having the above-mentioned magnetic field components By and Bz exists in the electron beam passage area inside the internal magnetic shield, so that the landing deviation shown in FIGS. 8A and 8B is caused. Color purity is deteriorated.

However, the landing deviation due to the vertical axis component By of the magnetic field shown in FIG. 8B can be dealt with by slightly changing the specifications when forming the phosphor screen in accordance with the destination of the color picture tube. Since the landing deviation due to the tube axis direction component Bz of the magnetic field shown in FIG. 8A varies variously depending on the actual operation and use of the color picture tube, it is necessary to take measures when forming the phosphor screen. It is impossible.

In order to reduce the landing deviation due to the tube axis direction component Bz of the magnetic field shown in FIG. 8A, Japanese Unexamined Patent Publication No. 53-15061 discloses a short rectangular trapezoid as shown in FIG. An internal magnetic shield 14a having a V-shaped notch 17 on the side is shown. In addition, 55-29898
The publication discloses that magnetic shields are unevenly distributed on the upper and lower ends of a screen.

When such a magnetic shield is used, when the color picture tube is installed to the north, the magnetic field lines in the tube axis direction are forcibly applied in the long side direction of the magnetic shield, and the vertical axis component By increases accordingly. I do. That is, + y direction (positive direction)
+ By increases in the -y direction (negative direction).
The electron beam shifts to the right at the top of the screen and to the left at the bottom of the screen, causing a landing shift of right rotation. This reduces the leftward landing deviation shown in FIG. 8 (a), and therefore improves the color purity when the color picture tube is installed facing north or south.

However, in the above structure, when the color picture tube is installed eastward or westward, the horizontal axis component Bx of the terrestrial magnetism easily passes through the inside of the internal magnetic shield 14a. Therefore, the magnetic flux density in the electron beam passage area inside the internal magnetic shield 14a increases, and the barrel-shaped magnetic field inside the electron beam passage area is strengthened. For example, when the color picture tube is installed facing east, as shown in FIG. 10, the magnetic field 18 inside the tube becomes more barrel-shaped, and the closer to the screen corner portion, the component of the vertical axis direction By increases. The trapezoidal landing deviation shown occurs. When the color picture tube is installed westward, a landing displacement (reverse trapezoidal shape) occurs in the direction opposite to the arrow 16c.

[0012] In short, the conventional color picture tube, even if the internal magnetic shield is arranged, to reduce the landing deviation when it is installed to face north or south, it is necessary to install it in the east or west. Is increased, and it is impossible to improve the color purity by reducing the landing deviation in all directions.

In addition, the influence of an external magnetic field such as terrestrial magnetism on the landing becomes greater as the size of the color picture tube becomes larger. For example, in the case of a very large color picture tube of about 37 inches, the distance from the electron gun to the phosphor screen becomes longer. 2
Compared to a 1-inch color picture tube, the size is about 1.7 times, and the moving amount of the electron beam is about 2.8 times. In addition, the distance between the phosphor screen and the shadow mask is increased, and the electron beam travel distance is correspondingly increased.

As for the 37-inch color picture tube in which the internal magnetic shield was actually arranged, the landing deviation due to the geomagnetism in Japan was measured. As a result, the color picture tube was turned from south to north and from west to east. When they were oriented, they both moved about 50 μm. In addition, the aspect ratio of the phosphor screen which is being developed recently is 16:
In the high-definition color picture tube having a horizontally long screen of No. 9, the arrangement pitch of the phosphor layers is reduced to 0.5 to 0.7 mm. For example, even in a 37-inch super large color picture tube for consumer use, the arrangement of the phosphor layers is large. The pitch is about 0.7 mm at the center of the screen and about 0.8 mm at the periphery of the screen. Considering the variation in the manufacturing process, the allowance of the moving amount of the electron beam is 30 to 4
0 μm. On the other hand, the actual movement amount of the electron beam is about 60 μm when moving from the south to the north, and about 30 μm when moving from the west to the east, so that the screen quality is greatly deteriorated.

That is, for a very large color picture tube,
Due to the influence of an external magnetic field such as terrestrial magnetism, even if an internal magnetic shield is arranged, the landing deviation is large, and the color purity is significantly deteriorated.

[0016]

As described above, in a color picture tube, an internal magnetic shield is arranged inside a funnel in order to avoid the influence of an external magnetic field such as terrestrial magnetism. However, even if the internal magnetic shield is provided, the conventional internal magnetic shield does not have a sufficient shielding effect, causing a landing deviation of the electron beam with respect to the three-color phosphor layer, and the color purity is deteriorated. In particular, in the case of a very large color picture tube, not only the amount of movement of the electron beam becomes large, but also in the case of a high-quality color picture tube, the arrangement pitch of the phosphor layers becomes finer, and the margin of the amount of movement of the electron beam becomes small. To become
The color purity is greatly deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The present invention has been made to reduce the amount of movement of an electron beam by an external magnetic field such as terrestrial magnetism, and is intended to use not only ordinary color picture tubes but also super-large color picture tubes. It is also an object of the present invention to improve the color purity of high-quality color picture tubes.

[0018]

SUMMARY OF THE INVENTION An envelope comprising a panel and a funnel, and a phosphor screen formed on the inner surface of the panel are disposed inside the panel so as to face the phosphor screen. A shadow mask consisting of a mask body having a skirt portion formed on the outer periphery of the portion, a mask frame having a side wall portion parallel to a pipe axis attached to the mask body with the skirt portion inside, and a mask attached to the mask frame. In a color picture tube including a magnetic shield disposed inside a funnel and an electron gun disposed in a neck of the funnel, a mask frame is formed of a magnetic material, and a side wall of the mask frame is formed of a mask body. The skirt extends to the phosphor screen side from the phosphor screen side end, and extends to the phosphor screen side. The length A is defined as the distance from the phosphor screen side end of the skirt portion of the mask body to the inner surface of the panel, and the effective outermost portion of the mask body from the phosphor screen side end of the skirt portion of the mask body. When the distance between the electron beam passing through the electron beam passage hole and the intersection of the side wall of the mask frame and the extension to the phosphor screen side is C, the entire circumference or a part of the side wall of the mask frame is B /. A size satisfying the relationship of 5 ≦ A <C [ unit: mm] and B / 5 ≦ A ≦ B-5 [unit: mm] .

[0019]

When the mask frame of the shadow mask is configured as described above, when the color picture tube is installed facing north or south, the space between the phosphor screen and the shadow mask arranged close to the phosphor screen is increased. The external magnetic field that passes can be canceled out by the emission magnetic field radiated into the space from the phosphor screen side end of the side wall of the mask frame, which occurs when the conventional color picture tube is installed facing north or south. The landing deviation (see FIG. 8A ) can be effectively reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments.

FIG. 1A shows the overall structure of a color picture tube according to an embodiment of the present invention, and FIG.

This color picture tube has an envelope consisting of a substantially rectangular panel 1 and a funnel 2 integrally formed with the panel 1 and having a funnel shape.
A phosphor screen 3 comprising three color phosphor layers emitting blue, green, and red light is formed, and a substantially rectangular shadow mask 20 is disposed inside and close to the phosphor screen 3. A substantially rectangular mask frame of stud pins 21 fixed to the four corners and a shadow mask 20 described later.
A substantially V-shaped resilient support 23 is attached to the four corners of the panel 22 and fitted and locked to the stud pins 21, and is supported inside the panel 1. An internal magnetic shield 14 located inside the funnel 2 is attached to the mask frame 22. Further, an electron gun 11 for emitting three electron beams 10 is arranged in the neck 9 of the funnel 2.

Reference numeral 12 denotes a deflection yoke mounted outside the funnel 2.

The shadow mask 20 has a substantially rectangular mask body 26 having a skirt portion 25 formed on the outer periphery of an effective portion in which a number of electron beam passage holes 24 are formed, and a tube axis (Z axis).
A mask frame 22 made of a magnetic material such as a substantially rectangular low carbon steel plate having an L-shaped cross section and having a side wall 27 parallel to the side wall and a protrusion 28 projecting inward from an end of the side wall 27 on the electron gun 11 side. The mask body 26 has a skirt 25 attached to the inside of a middle portion of a side wall 27 of the mask frame 22 by welding, and an end of the side wall 27 on the side of the phosphor screen 3 is attached to the mask body 26. Of the mask, ie the mask body
26 than the end of the skirt 25 on the phosphor screen 3 side
It extends to the phosphor screen 3 side.

Further, the length A of the portion of the side wall 27 of the mask frame 22 extending toward the phosphor screen 3 is such that the electron beam 10a passing through the outermost effective electron beam passage hole 24a of the mask body 26 can be used. The distance C from the end of the skirt portion 25 of the mask body 26 on the phosphor screen 3 side to the intersection 29 between the trajectory of the electron beam 10a and the extension line of the side wall portion 27 to the phosphor screen 3 so as not to block. Is also shorter
(A <C). However, depending on the nominal deflection angle or deflection direction of the color picture tube, the electron beam 10a that reaches the inner surface of the panel 1 through the outermost electron beam passage hole 24a of the effective portion of the mask body is directed to the phosphor screen 3 side wall 27. In some cases, it is closer to the tube axis than the extension of the side wall and does not intersect with the extension of the side wall portion toward the phosphor screen. In this case, it is not necessary to particularly consider the relationship with the trajectory of the electron beam 10a.

However, even in such a case, it is necessary to consider the interval (margin) between the inner surface of the panel 1 and the end of the side wall 27 on the phosphor screen 3 side. That is, when the distance between the inner surface of the panel 1 and the end portion of the side wall portion 27 on the side of the phosphor screen 3 becomes smaller, the shadow mask 20 which is repeatedly performed in the process of manufacturing a color picture tube, such as the process of forming the phosphor screen, etc.
At the time of attachment / detachment, the end of the side wall portion 27 on the side of the phosphor screen 3 hits and damages the inner surface of the panel 1, and the panel 1 and the funnel 2 are joined (sealed) after the phosphor screen 3 is formed.
Alternatively, cracks are likely to occur during high-temperature heating in the exhaust process.

According to the experimental results of the present inventor, the distance between the inner surface of the panel 1 and the end of the side wall 27 on the side of the phosphor screen 3 is appropriately about 5 mm, depending on the size of the color picture tube. . Of course, this interval can be set smaller if the shadow mask 20 is attached to and detached from the panel 1 carefully, but if the interval becomes smaller, the workability of attaching and detaching the shadow mask 20 will decrease in proportion to the interval, and the mass mask will not be suitable for mass production. .

That is, the length A of the portion of the side wall 27 of the mask frame 22 extending toward the phosphor screen 3 is equal to the distance from the phosphor screen 3 end of the skirt 25 of the mask body 26 to the inner surface of the panel 1. It is formed so as to satisfy A ≦ B-5 [unit: mm] with respect to the distance B.

By the way, as described above, the shadow mask 20
When the color picture tube is installed facing south,
The magnetic field shown in FIG. For comparison, in the conventional color picture tube shown in FIG. 1B, the phosphor screen 3 on the side wall 7 of the mask frame 8 is generated by magnetism passing through the mask frame 8 via the internal magnetic shield 14 and the like.
The side end is magnetized to the N pole, and an emission magnetic field 31 is formed. A part of the emitted magnetic field 31 is directed toward the south pole formed on the side of the internal magnetic shield 14 and cancels and shields a part of the magnetism 32 passing through the electron beam passage area inside the internal magnetic shield 14. However, in the space between the phosphor screen 3 and the shadow mask 4, since the emission magnetic field 31 in the direction to cancel the magnetism 32 is not formed, no shielding effect for the magnetism 32 is obtained.

On the other hand, in the color picture tube of this example shown in FIG. 2A, like the above-mentioned conventional color picture tube,
The end portion of the side wall portion 27 of the mask frame 22 on the side of the phosphor screen 3 is magnetized to the N pole to form the emission magnetic field 31, and a part thereof faces the S pole on the side of the internal magnetic shield 14, Although a part of the magnetism 32 passing through the electron beam passage area inside 14 is canceled out, the emission magnetic field 31 of the color picture tube in this example is more intense than the conventional color picture tube in the side wall 27 on the side of the phosphor screen 3. Since the portion extends close to the phosphor screen 3 side, the emission magnetic field 31 extends to the phosphor screen 3 side. As a result, not only the electron beam passage area inside the internal magnetic shield 14 but also the inner surface of the panel 1 and the shadow mask 20.
The magnetism 32 passing through the space between and also cancels out.

FIG. 3 shows that in the case of a 36-inch high-definition color picture tube having an aspect ratio of 16: 9, the length A of the side wall portion of the mask frame extending toward the phosphor screen is variously changed. The result of measuring the landing deviation due to geomagnetism is shown. The N / S movement amount shown on the vertical axis of the figure is:
The landing deviation amount when the color picture tube is turned from north to south, and the E / W movement amount is the landing deviation amount when moving from east to west. The horizontal axis represents the length A of the portion of the side wall portion extending toward the phosphor screen, as a ratio to the distance B from the phosphor screen side end of the skirt portion of the mask body to the panel inner surface. . FIG.
The curve 33 shown in (a) is the N / S movement amount at the screen diagonal axis end, the line 34 is the E / W movement amount also at the screen diagonal axis end, and the curve 35 in (b) is the screen vertical axis. This is the N / S movement amount at the end.

As shown in FIG. 3A, at the end of the diagonal axis of the screen, in the case of the conventional color picture tube where A / B = 0, that is, A = 0, the N / S movement amount is about 60 μm. , The E / W movement amount is about 30 μm, especially the N / S movement amount is large,
For a high-definition color picture tube with a small arrangement pitch of the phosphor layers, the screen quality is greatly deteriorated, but as A is increased, the amount of N / S movement is greatly reduced. A size that does not hinder the electron beam passing through the electron beam passage hole at the outermost part of the effective portion and land the phosphor layer, that is, the maximum size A of A / B ≦ 40% calculated from the geometrical size of the color picture tube. / B
= 40%, it is about 20 μm, and the N / S movement amount can be reduced to 1/3 compared to the case of A = 0 in the conventional color picture tube.

As shown in FIG. 3B, at the end of the vertical axis of the screen, in the case of the conventional color picture tube where A / B = 0,
The amount of N / S movement is about 30 μm, but the amount of N / S movement decreases as A is increased, and the distance between the N / S and the inner surface of the panel does not matter. Does not hinder the electron beam), that is, the maximum dimension A / B = A = B−5 mm
At 60%, the distance is about 10 μm, and the N / S movement amount can be reduced to １ ／ of that of the conventional color picture tube when A = 0.

In addition, N / N at the screen diagonal axis end and the vertical axis end
The decrease in the amount of S movement clearly appears when A / B ≧ 20%, and when A ≧ B / 5, an effective magnetic shielding effect can be obtained.

FIG. 3A shows the E / W movement amount.
As shown in the figure, there is almost no change. This means that if A is increased, the magnetism passing through the space between the inner surface of the panel and the shadow mask is canceled out, and the magnetic flux density of the unnecessary magnetic field in this space is reduced. On the contrary, as shown in FIG. The barrel component of the magnetic field inside the mask frame increases. Therefore, the E / W movement amount does not substantially change overall.

The same test was conducted on a 37-inch type color picture tube having an aspect ratio of 4: 3. FIG. As shown by the curve 37, the W movement amount of the conventional color picture tube (A / B = 0, A = 0), the N / S movement amount and the E / W movement amount at the screen diagonal axis end are: Both are about 50μ
m, the N / S movement amount and the E / W movement amount both decrease as A increases, and in particular, the N / S movement amount largely decreases. In this color picture tube, the size of the side wall of the mask frame that does not hinder the electron beam passing through the outermost effective electron beam passage hole of the shadow mask and landing on the phosphor layer is A / B ≦ 45%. The maximum dimension A / B = 45% is about 15 μm, and the N / S moving amount is about 3 μm compared to the conventional color picture tube.
It can be reduced to 0%. Further, the decrease in the N / S moving amount clearly appears because A / B ≧ 20%, that is, A / B as in the case of the 36-inch type high-definition color picture tube.
≧ B / 5. On the other hand, the E / W movement amount does not show a remarkable change unlike the N / S movement amount.

Further, as a result of performing the same test on a 34-inch color picture tube having an aspect ratio of 4: 3, FIG.
As shown by the curve 39, the E / W movement amount of the conventional color picture tube (A / B = 0, A = 0) shows that the N / S movement amount at the diagonal end of the screen is about 40 μm, / W movement amount is about 35
However, as A is increased, both the N / S movement amount and the E / W movement amount are reduced, and in particular, the N / S movement amount is greatly reduced. In this color picture tube, the size of the 37-inch color picture tube is such that the side wall of the mask frame does not obstruct the electron beam passing through the outermost electron beam passage hole of the shadow mask and landing on the phosphor layer. A / B ≦ 45% as in the case of the tube, and when its maximum dimension A / B = 45%, it is about 10 μm, and the N / S movement amount is reduced to about 25% with respect to the conventional color picture tube. Can be. Further, the decrease in the N / S movement amount clearly appears when A / B ≧ 20%, that is, when A ≧ B / 5. On the other hand, the E / W movement amount does not show a remarkable change like the N / S movement amount similarly to the 37-inch type color picture tube.

In short, in the color picture tube of this embodiment, the side wall 27 of the mask frame 22 of the shadow mask 20 extends from the end of the skirt 25 of the mask body 26 on the side of the phosphor screen 3 to the phosphor screen 3 side. By setting the length A of the portion to a size satisfying B / 5 ≦ A <C [unit: mm] and B / 5 ≦ A ≦ B-5 [unit: mm] , at least E / W
Without deteriorating the movement amount, the N / S movement amount is greatly reduced, and a good magnetic shielding effect can be obtained.

In the above embodiment, the color picture tube supporting the shadow mask at the four corners has been described. However, the present invention is also applicable to a color picture tube supporting the shadow mask at other than the four corners.

[0040]

According to the present invention, the side wall parallel to the tube axis of the mask frame of the shadow mask, which is disposed inside and opposing the phosphor screen formed on the inner surface of the panel, is provided on the phosphor screen side end of the skirt portion of the mask body. And the length A of the extended portion is defined as the distance from the phosphor screen side end of the skirt portion of the mask main body to the inner surface of the panel, and the length A of the extending portion is defined as the length of the skirt portion of the mask main body. Let C be the distance from the phosphor screen side end to the point where the electron beam passing through the outermost effective electron beam passage hole of the mask body intersects the extension of the side wall of the mask frame to the phosphor screen side. When the entire circumference or a part of the side wall of the mask frame is set to a size satisfying the relationship of B / 5 ≦ A <C [unit: mm] and B / 5 ≦ A ≦ B-5 [unit: mm]. , Phosphor The external magnetic field passing through the space between the clean and the shadow mask is offset by the emission magnetic field radiated into the space from the phosphor screen side end of the side wall of the mask frame, and the landing deviation caused in the conventional color picture tube. Can be effectively reduced, and a color picture tube with good color purity can be obtained.

[Brief description of the drawings]

FIG. 1A is a diagram showing an entire configuration of a color picture tube according to an embodiment of the present invention, and FIG. 1B is an enlarged view showing a main part thereof.

FIG. 2 (a) is a diagram for explaining the magnetic shielding effect of the color picture tube of the above-mentioned embodiment, and FIG. 2 (b) is a graph showing the magnetic shielding effect of a conventional color picture tube shown for comparison. It is a figure for explaining.

FIG. 3A is a diagram for explaining an N / S movement amount and an E / W movement amount at a diagonal end of a screen of the 36-inch type high-definition color picture tube of the embodiment. FIG. 3B is a diagram for explaining the amount of N / S movement at the vertical axis end of the screen.

FIG. 4 is a view for explaining an N / S movement amount and an E / W movement amount at a diagonal end of a screen of the 37-inch color picture tube.

FIG. 5 is a view for explaining an N / S movement amount and an E / W movement amount at a diagonal end of a screen of the 34-inch color picture tube.

FIG. 6 is a diagram showing a configuration of a conventional color picture tube.

FIG. 7 is a diagram showing a basic structure of the internal magnetic shield.

8 (a) and 8 (b) are views showing landing deviations of a conventional color picture tube using the above-mentioned internal magnetic shield, respectively.

FIG. 9 is a diagram showing the structure of a conventional improved internal magnetic shield.

FIG. 10 is a view showing a landing deviation of a color picture tube using the improved internal magnetic shield.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Panel 2 ... Funnel 3 ... Phosphor screen 11 ... Electron gun 14 ... Internal magnetic shield 20 ... Shadow mask 21 ... Stud pin 22 ... Mask frame 23 ... Elastic support 24 ... Electron beam passage hole 25 ... Skirt part 26 ... Mask body 27 ... Side wall

Claims (1)

(57) [Claims] 1. An outer periphery formed of a panel and a funnel, and an effective portion disposed inside the panel opposite to a phosphor screen formed on an inner surface of the panel and having a plurality of electron beam passage holes formed therein. A shadow mask comprising a mask body having a skirt portion formed thereon, and a mask frame having a side wall portion parallel to a tube axis attached to the mask body with the skirt portion inside; and the funnel attached to the mask frame. In a color picture tube provided with a magnetic shield disposed inside and an electron gun disposed in the neck of the funnel, the mask frame is made of a magnetic material, and the side wall of the mask frame is The skirt portion of the mask body extends to the phosphor screen side from the phosphor screen side end, and the phosphor screen The length A of the portion extending toward the screen side is defined as a distance from the phosphor screen side end of the skirt portion of the mask body to the inner surface of the panel, and the phosphor screen side end of the skirt portion of the mask body. When the distance from the portion to the intersection of the electron beam passing through the outermost effective electron beam passage hole of the mask body and the extension of the side wall of the mask frame toward the phosphor screen is C, A color characterized in that the entire circumference or part of the side wall of the frame satisfies the relationship of B / 5 ≦ A <C [unit: mm] and B / 5 ≦ A ≦ B-5 [unit: mm]. Picture tube.