JPH10233173A - Color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color picture tube in which a color deviation error is unlikely to occur as mislanding that is likely to occur at the intermediate part of a screen due to the doming of a shadow mask and mislanding due to the vibration of the shadow mask are restrained. SOLUTION: A color picture tube has a substantially rectangular shadow mask, in which a plurality of lines of slits 39 are formed along the direction of the minor axis of an effective screen comprising a curved surface opposite to a phosphor screen formed on the inner surface of an effective part comprising the curved surface of a substantially rectangle panel, etch of the lines comprising plural slits 39 arranged with bridges 38 between them along the direction of the minor axis of the effective screen. In this case, the width B of the bridge at the intermediate part of the effective surface of the shadow mask along the direction of the lines of slits is made greater than the width of the bridge at the periphery of the effective surface along the direction of the lines of slits.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type color picture tube, and more particularly to a color picture tube which suppresses doming of a shadow mask having a slit-shaped opening.

[0002]

2. Description of the Related Art Generally, in a color picture tube, a shadow mask is arranged so as to face a phosphor screen formed of a three-color phosphor layer which emits blue, green and red light formed on the inner surface of a panel. By scanning the phosphor screen with three electron beams emitted from the electron gun through the electron gun, a color image is displayed. The shadow mask is used to select the three electron beams so as to land on the predetermined three-color phosphor layers. In order to improve the color purity of the color image drawn on the phosphor screen, It is necessary to select the three electron beams so as to properly land on the predetermined three-color phosphor layer. For this purpose, during the operation of the color picture tube, the shadow mask is always kept in a predetermined relationship with the phosphor screen, that is, the distance (q value) between the shadow mask and the phosphor screen is always in a predetermined allowable range. It is necessary to keep.

However, in a shadow mask type color picture tube, the electron beam reaching the phosphor screen is generally less than one third of the electron beam emitted from the electron gun, and the other electron beams impinge on the shadow mask. . Therefore, the shadow mask is heated by the collision of the electron beam, and causes so-called doming which swells toward the phosphor screen. During this doming, the mask body in which the aperture of the shadow mask is formed is mainly heated, and the operation of the color picture tube caused by the temperature difference between the mask body and the mask frame attached to the periphery of the mask body is started. There are initial doming and local doming that occurs in a relatively short time when the mask body is locally heated by an electron beam for displaying a high-intensity image. If the position change of the shadow mask due to the doming exceeds the allowable range of the q value, the landing of the electron beam on the three-color phosphor layer shifts, and the color purity is deteriorated. The landing deviation of the electron beam due to the doming greatly differs depending on the position of the image pattern on the screen, the luminance, the duration of the high luminance image pattern, and the like.

FIG. 6 shows local doming that occurs when a high-luminance image is locally displayed on the screen. The shadow mask 1 is formed by engaging a stud pin 3 provided on the panel 2 with an elastic support 6 fixed to a mask frame 5 attached through a non-perforated portion around the mask body 4. Is supported at a position shown by a solid line at a predetermined interval from the phosphor screen 7 formed on the inner surface of the light emitting element. Even if the electron beam 8 having a low current density for displaying a low luminance image collides with the shadow mask 1, in this case,
The position of the electron beam 8 hardly changes, and the electron beam 8 that has passed through one opening 9 at the position A properly land on a predetermined phosphor layer 10. However, when the electron beam 8 having a high current density for locally displaying a high-brightness image collides, the shadow mask 1 is locally heated and expanded as indicated by a dashed line. As a result, the position of the aperture 9 moves from A to B, and the electron beam 8 does not land properly on a predetermined phosphor layer 10, and a color shift occurs. The local landing deviation that appears when a locally high-brightness image is displayed is more likely to occur closer to the short side than the center of the screen. As shown in FIG. )
It is likely to occur at the intermediate portion 12 with the end (short side).

The local landing deviation caused by the local thermal expansion of the shadow mask 1 is caused by a shadow mask having a small curvature, that is, for improving the visibility of an image.
The effective part of the panel is flattened, and the flattened surface of the mask main body 4 is more likely to occur as the flattened surface of the panel. Therefore, in order to prevent color misregistration due to local doming, it is desired to increase the curvature of the shadow mask.

For this reason, conventionally, the three-color phosphor layer constituting the phosphor screen has a vertically elongated stripe shape, and a plurality of slit-shaped apertures are vertically arranged in a row corresponding to the phosphor screen. In a striped color picture tube having a shadow mask in which a plurality of rows of vertical apertures are formed in parallel in the horizontal direction, the horizontal spacing between the striped three-color phosphor layers is set to From the center of the body screen, the horizontal spacing is gradually increased from the center of the screen, and the horizontal spacing of the aperture rows of the shadow mask is also gradually increased in the horizontal direction from the center of the shadow mask. The curvature is increased.

[0007]

When a high-brightness image is locally displayed on the screen as described above, the shadow mask is locally caused by the collision of a high current density electron beam for displaying the high-brightness image. Local landing deviation caused by heating is more likely to occur closer to the horizontal axis end than to the center of the screen, and particularly to an intermediate portion between the center of the screen and the horizontal axis end. The landing deviation caused by the local thermal expansion of the shadow mask is more likely to occur in a shadow mask having a smaller curvature. Therefore, in order to reduce landing deviation due to local thermal expansion of the shadow mask and prevent color deviation, it is desired to increase the curvature of the shadow mask. For this reason, conventionally, the three-color phosphor layers constituting the phosphor screen are vertically elongated stripe-shaped, and a plurality of slit-shaped apertures are arranged in a row in the vertical direction corresponding to the phosphor screen. In a striped color picture tube having a shadow mask in which a plurality of rows of vertical apertures are formed in parallel in the horizontal direction, the horizontal spacing between the stripe-shaped three-color phosphor layers is set to the width of the phosphor screen. In the horizontal direction from the center, the horizontal interval between the aperture rows of the shadow mask is also gradually increased in the horizontal direction from the center of the shadow mask, thereby increasing the curvature of the horizontal cross section of the shadow mask. As a result, landing deviation due to local thermal expansion of the shadow mask is suppressed.

Recently, however, a color picture tube having a flat panel is becoming the mainstream, and in a color picture tube having a flat panel, the curved surface of the shadow mask is entirely flat. Therefore, it is difficult to eliminate the landing deviation by suppressing the doming due to the heating, particularly the local doming that occurs in a relatively short time, only by increasing the curvature in the horizontal section as in the shadow mask.

The reason why the local landing deviation caused by the local heating of the shadow mask is likely to occur in the middle between the center of the screen and the end of the horizontal axis is related to the doming and the deflection angle of the electron beam. In the vicinity of the vertical axis, even if doming occurs, the deflection angle is small, so the landing deviation is small, and in the vicinity of the peripheral part of the screen, a mask frame with a large heat capacity is attached to the peripheral part of the mask body through a non-porous part Therefore, the heat of the mask main body is diffused in the mask frame direction, the landing deviation is reduced, and eventually, the heat is likely to be generated in the intermediate portion having a relatively large deflection angle.

In the color picture tube, in addition to the landing deviation due to the thermal expansion of the shadow mask, when the color picture tube is vibrated by the sound of a speaker or the like during the operation of the television set, the mask body vibrates. A characteristic that suppresses landing displacement (howling) is also required. As for this howling characteristic, since the peripheral part of the mask body is fixed to the mask frame via the non-porous part, the vibration amplitude is small at the peripheral part of the shadow mask, and the landing deviation is at the middle part slightly inside from the peripheral part of the screen. Is the largest.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the thermal expansion of a shadow mask, in particular, a color shift due to local doming near an intermediate portion of a screen, and a case where vibration is applied to the shadow mask. An object of the present invention is to configure a color picture tube that suppresses landing displacement.

[0012]

A phosphor screen is formed on an inner surface of an effective portion formed of a curved surface of a substantially rectangular panel, and a plurality of effective surfaces formed of a curved surface opposed to the phosphor screen are arranged in a short axis direction. In a color picture tube having a substantially rectangular shadow mask in which a plurality of slit-shaped apertures are arranged in a row via a bridge, and a plurality of rows of the apertures in the short-axis direction are arranged in the long-axis direction. The width of the bridge in the aperture row direction at the middle portion of the effective surface of the shadow mask was formed larger than the width of the bridge around the effective surface in the aperture row direction.

In addition, a phosphor screen is formed on the inner surface of the effective portion formed of a curved surface of a substantially rectangular panel, and a plurality of slit-shaped openings are formed in the short axis direction of the effective surface formed of the curved surface facing the phosphor screen. In a color picture tube having a substantially rectangular shadow mask in which holes are arranged in a row through a bridge and a plurality of rows of the apertures in the short axis direction are formed in a plurality of rows in the long axis direction. When the major axis of the effective surface is the x-axis and the minor axis is the y-axis, the width of the bridge in the direction of the aperture row is formed to a size represented by a fourth power polynomial of x and y.

Furthermore, the width B of the bridge in the row direction of the apertures
(X, y) was formed in a size represented by the following equation 2 using c as a coefficient.

[0015]

(Equation 2)

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color picture tube which is one embodiment of the present invention. This color picture tube comprises a substantially rectangular panel 22 provided with a skirt portion 21 around the effective portion 20 having a curved surface, and a funnel-shaped funnel 23 joined to the skirt portion 21. It has an enclosure. The inner surface of the effective portion 20 of the panel 22 is formed of an aspherical concave curved surface, and the inner surface of the effective portion 20 has a stripe shape 3 that is elongated in the vertical direction (short axis direction) that emits blue, green, and red light. A phosphor screen 24 in which color phosphor layers are formed in parallel in the horizontal direction (x-axis direction) (long-axis direction) is provided. A substantially rectangular shadow mask 25 is disposed inside the panel 22 so as to face the phosphor screen 24. The shadow mask 25 has a substantially rectangular mask body 26 having an effective surface formed of a curved surface having a large number of slit-shaped openings formed therein and having a non-perforated portion formed in the periphery thereof, as described later. It comprises a substantially rectangular mask frame 17 attached to the periphery of the mask body 26, and a stud pin 28 provided on the skirt 21 of the panel 22 and a stud pin 28 attached to the mask frame 27 to engage with the stud pin 28. The elastic support 29 is stopped, so that the effective surface of the mask body 26 is supported inside the panel 22 so as to face the phosphor screen 24 at a predetermined distance. In the neck 31 of the funnel 23, three electron beams 32B, 32G,
An electron gun 33 for emitting 32R is arranged.

Then, 3 emitted from the electron gun 33
The electron beams 32B, 32G, and 32R are deflected by a magnetic field generated by a deflecting device 35 mounted on the outside of the funnel 23, and the phosphor screen 24 is horizontally and vertically scanned through the aperture of the shadow mask 25. 2 is formed to display a color image in a rectangular area 36 shown in FIG.

The slit-shaped openings of the shadow mask 25 correspond to the stripe-shaped three-color phosphor layers of the phosphor screen 24 and, as shown in FIG. The slit-shaped openings 39 are arranged in a row at a predetermined arrangement pitch PV, and the vertical rows are arranged in parallel in a plurality of rows at a predetermined arrangement pitch PH in the horizontal direction.

In particular, the shadow mask 2 in this embodiment
In FIG. 5, the width B of the bridge 38 between the vertical openings 39 in the opening row direction differs depending on the position, and FIG. The width of the bridge in the direction of the opening row at the point (a) is changed as indicated by the broken line 42. That is, as shown in FIG.
The width of the center O bridge in the direction of the opening row is BO, the width of the bridge at the end of the vertical axis in the direction of the opening row is BV, the width of the bridge at the end of the horizontal axis in the direction of the opening row is BH, and the end of the diagonal axis is BH. When the width of the bridge in the opening row direction of the bridge on the horizontal axis is BD, the width of the bridge on the middle part on the horizontal axis in the opening row direction is BMH, and the width of the bridge on the middle part of the long side in the opening row direction is BML, BMH > BH BMH> BD BMH> BML, and the width of the bridge at the middle portion in the horizontal direction in the opening row direction is larger than the width of the other portion of the bridge in the opening row direction.

As described above, the width B of the bridge in the row direction of the apertures is obtained.
In the shadow mask in which the arrangement pitch PV of the vertical holes 39 shown in FIG. 3 is constant over the entire effective surface and the width D of the holes 39 is constant as shown in FIG. Although the area (opening ratio) of the opening 39 is reduced, the heat capacity of the effective surface is partially increased. Therefore, as described above, by increasing the width B of the bridge at the middle portion in the horizontal direction in the opening row direction, the heat capacity of the middle portion in the horizontal direction can be made larger than the heat capacity of other portions such as the peripheral portion.

Therefore, when the shadow mask is configured as described above, when a high-brightness image is locally displayed at an intermediate portion on the horizontal axis of the screen where the landing deviation is largest due to doming, the heat capacity of this portion is large.
The temperature rise rate of this portion can be reduced. Furthermore, even if heat flows to the peripheral portion due to heat conduction, the peripheral portion has a small heat capacity, so the temperature rise is large, and the peak of the temperature difference between the intermediate portion and the peripheral portion can be reduced. As a result, local doming of the mask body that occurs in a short period of time can be suppressed, and landing deviation due to this local doming can be suppressed. Degradation of color purity due to landing deviation on the screen corresponding to the horizontal middle part of the shadow mask Can be reduced.

The bridge width B of the shadow mask can be easily realized by the following setting means. In other words, x, y with the horizontal axis and the vertical axis passing through the center of the effective surface as two orthogonal axes
In the coordinate system, using c as a coefficient, the width B (x, y) of the bridge in the aperture row direction over the entire effective surface is expressed as x,
It is set by the fourth power polynomial of y.

[0024]

(Equation 3) The width B of the bridge in the opening row direction set by the equation (3)
(X, y) is, for example, in the shadow mask for a 28-inch color picture tube, the bridge width at the center B0 = 0.160 mm, the bridge width at the middle part on the long axis BMH = 0.160 mm, the bridge width at the end of the long axis BH = 0 130 mm Bridge width at the end of the short axis BV = 0.140 mm Bridge width at the middle of the long side BML = 0.125 mm Bridge width at the end of the diagonal axis BD = 0.140 mm, and the coefficient c is c0 = 1.600000 × 10 ^-01 c1 = 4.175079 × 10 ^-07 c2 = −1.181269 × 10 ⁻¹¹ c3 = −6.110379 × 10 ⁻⁰⁷ c4 = −6.407131 × 10 ⁻¹¹ c5 = 1.082887 × 10 ^By selecting ^-15 c6 = -1.219065 × 10 ^-11 c7 = 3.618716 × 10 ^-16 c8 = -1.471625 × 10 ^-21 , a slit-shaped opening at the intermediate portion on the long axis is selected. The area of For slit-shaped openings in the peripheral part,
The heat capacity can be increased by about 10%. As a result, when locally displaying a high-brightness image, not only can the doming of the intermediate portion on the long axis, where local doming is most likely to occur, besides, the initial operation of the color picture tube, the mask body and its surroundings can be suppressed. Doming caused by a temperature difference from the mask frame attached to the portion can also be reduced, and deterioration in color purity due to a landing shift of the electron beam with respect to the three-color phosphor layer can be reduced.

When the bridge width is increased, the strength of the curved surface of the mask body can be improved. Accordingly, by increasing the bridge width at the intermediate portion with respect to the peripheral portion as described above, the strength of the curved surface of the mask body is relatively larger at the intermediate portion than at the peripheral portion of the effective portion. On the other hand, when vibration is applied to the color picture tube by the sound from the speaker of the TV set, the periphery of the effective portion of the mask body is attached to the relatively strong non-porous portion or the mask frame, Vibration is difficult, and the amplitude of the vibration of the mask body is relatively large in the middle portion.
Therefore, if the strength of the middle part of the mask body is improved,
The amplitude of the vibration of the intermediate portion can be effectively reduced, thereby suppressing the deterioration of the image caused by the vibration of the shadow mask.

When the bridge width is changed as described above, the area of the slit-shaped aperture changes, and the light-emitting area of the three-color phosphor layer changes accordingly, affecting the brightness of the screen. In general, the effective part of the panel is thicker at the periphery than at the center, especially in the case of dark tint panels, which have recently been used to improve contrast, since the brightness at the periphery of the screen decreases in the direction of shadow. Increasing the bridge width in the middle of the effective surface of the mask to reduce the area of the slit-shaped aperture and relatively increasing the area of the slit-shaped aperture in the peripheral area does not cause a problem, but rather the periphery of the screen. By improving the brightness of the portion, a favorable result that the brightness over the entire screen can be made uniform can be obtained.

[0027]

According to the present invention, a phosphor screen is formed on the inner surface of an effective portion formed of a curved surface of a substantially rectangular panel, and a plurality of slit-shaped openings are formed in the short axis direction of the effective surface formed of a curved surface facing the phosphor screen. In a color picture tube having a substantially rectangular shadow mask in which holes are arranged in a row through a bridge and a plurality of rows of the apertures in the short axis direction are formed in a plurality of rows in the long axis direction. The width of the bridge in the opening row direction at the middle of the effective surface is formed larger than the width of the bridge in the opening row direction at the periphery of the effective surface, and the major axis of the effective surface of the shadow mask is the x-axis. When the short axis is the y-axis, the width of the bridge in the direction of the opening row is formed to a size represented by a fourth power polynomial of x and y, and the width B (x , Y) is represented by the following equation 4 using c as a coefficient. When formed of wood,

(Equation 4) By increasing the heat capacity of the middle part of the effective surface of the shadow mask where doming is most likely to occur due to electron beam collision,
Deterioration of the color purity of the color picture tube due to the displacement of the electron beam landing on the three-color phosphor layer can be reduced. In particular, the panel is flattened so that the reflection looks natural, and the effective surface of the shadow mask is flattened accordingly. A great effect can be obtained by applying the present invention to a color picture tube. Further, even if vibration is applied to the color picture tube, the vibration of the shadow mask can be reduced by improving the strength of the intermediate portion of the effective surface of the shadow mask, and the deterioration of the image due to the vibration of the shadow mask can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a color picture tube according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a screen of the color picture tube.

FIG. 3A is a view showing an arrangement of slit-shaped apertures of a shadow mask of the color picture tube, and FIG.
FIG. 111 is a sectional view taken along the line 111-111.

FIG. 4 is a diagram showing the width of a bridge between slit-shaped openings of a shadow mask of the color picture tube in the direction of the opening row.

FIG. 5 is a view for explaining a width of a bridge between slit-shaped openings of a shadow mask of the color picture tube in an opening row direction.

FIG. 6 is a diagram for explaining a landing deviation due to local doming of a shadow mask.

FIG. 7 is a diagram illustrating a position where a landing deviation occurs due to local doming of a shadow mask.

[Explanation of symbols]

 Reference Signs List 20 effective portion 22 panel 24 phosphor screen 25 shadow mask 38 bridge 39 slit-shaped opening 43 effective surface

Claims (3)

[Claims] 1. A phosphor screen is formed on an inner surface of an effective portion of a substantially rectangular panel having a curved surface, and a plurality of slit-shaped openings are formed in a short axis direction of the effective surface having a curved surface facing the phosphor screen. In a color picture tube having a substantially rectangular shadow mask in which holes are arranged in a row through a bridge, and a plurality of rows of short holes in the short axis direction are formed in the long axis direction. Wherein the width of the bridge in the aperture row direction at the intermediate portion of the effective surface is larger than the width of the bridge at the periphery of the effective surface in the aperture row direction. 2. A phosphor screen is formed on an inner surface of a substantially rectangular effective portion formed of a curved surface of a panel, and a plurality of slit-shaped openings are formed in a short axis direction of the effective surface formed of a curved surface facing the phosphor screen. In a color picture tube having a substantially rectangular shadow mask in which holes are arranged in a row through a bridge, and a plurality of rows of short holes in the short axis direction are formed in the long axis direction. When the major axis of the effective surface is the x-axis and the minor axis is the y-axis, the width of the bridge in the direction of the aperture row is formed to a size represented by a fourth power polynomial of x and y. A color picture tube characterized by the following. 3. The collar according to claim 2, wherein c is a coefficient, and a width B (x, y) of the bridge in the direction of the opening row is formed to a size represented by the following equation (1). Picture tube. (Equation 1)