JPH09259784A - Color cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain moire stripes from becoming conspicuous in respective area, and obtain an excellent image by changing a longitudinal pitch of a shadow mask with respective areas, and putting it in the relationship of (a longitudinal pitch of a corner part > a longitudinal pitch of a central part > a longitudinal pitch of a horizontal directional peripheral part). SOLUTION: A longitudinal pitch on a shadow mask or an image screen is changed, and when a longitudinal pitch of the shadow mask is formed as (an image screen corner part > an image screen central part), conspicuousness of moire stripes can be respectively restrained in the image screen corner part and the image screen central part. When it is formed as (the image screen central part > an image screen peripheral part on X axis), conspicuousness of the moire stripes can be respectively restrained in the image screen central part and the image screen peripheral part. When it is formed as (the image screen corner part > the image screen central part > the image screen peripheral part on the X axis), conspicuousness of the moire stripes by a difference in the apparent scanning line number in respective places of an image screen can be restrained, and the moire stripes can be optimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube using a shadow mask, and more particularly to a color cathode ray tube in which the occurrence of moire phenomenon due to a shadow mask and scanning lines is reduced.

[0002]

2. Description of the Related Art A cathode ray tube used for color image display comprises a panel portion which is an image screen, a neck portion which houses an electron gun, and a funnel portion which connects the panel portion and the neck portion. A deflection device for mounting an electron beam emitted from an electron gun on a phosphor screen coated and formed on the inner surface of the panel is mounted.

The electron gun housed in the neck portion is provided with various electrodes such as a cathode electrode, a control electrode, a focusing electrode and an accelerating electrode, and an electron beam from the cathode electrode is modulated by a signal applied to the control electrode. A desired cross-sectional shape and energy are applied through the focusing electrode and the accelerating electrode so that the fluorescent surface is bombarded. The electron beam is deflected in the horizontal and vertical directions by the deflection device provided in the funnel portion on the way from the electron gun to the phosphor screen, thereby forming an image on the phosphor screen. 59-215
640 publication).

A shadow mask structure used for a color picture tube generally has a shadow mask having a large number of electron beam passage holes, a support frame for holding the shadow mask, and a mask for holding the support frame in a panel of the color picture tube. It is composed of a spring.

In a conventional color cathode ray tube having a shadow mask having a periodic slot arrangement in the vertical direction, moire is caused by interference between electron beam scanning lines and a vertical slot hole period (hereinafter referred to as vertical pitch) of the shadow mask. There was the problem of streaks.

It is impossible to eliminate the moiré interference fringes. Conventionally, the vertical pitch is set so that the moiré fringes are inconspicuous, and the vertical pitch is kept constant to form a shadow mask.

The moire fringe period λ when the conventional horizontally adjacent electron beam passage holes (slot holes) are vertically displaced by 1/2 of the vertical pitch P is analytically given by the following general formula. .

[0008]

[Equation 1]

Here, V1 is the vertical diameter of the shadow mask effective surface, P is the vertical pitch, N is the number of electron beam scanning lines in the effective surface, and m is the moire fringe mode. Further, when m is an odd value, moire fringes are generated only when the scanning lines are paired (or when non-interlaced). Therefore, m is usually an even value.

Incidentally, as a related to the conventional shadow mask in which moire fringes are inconspicuous, Japanese Patent Publication No. 55-1 is available.
3371, JP-A-56-76144, JP-A-62-51135, JP-A-63-43241, JP-A-1-161641 and the like.

Further, as disclosed in, for example, Japanese Patent Publication No. 58-36458, the distance between the centers of the adjacent slot holes projected on the phosphor film in the vertical direction (vertical pitch) has the same value over the entire surface. In this case, the ratio between the scanning line interval and the vertical center distance of the adjacent slot holes projected on the phosphor film is made to be inconspicuous by selecting one optimum value in which moire fringes are inconspicuous.

[0012]

Conventionally, the panel which is the display surface of the color cathode ray tube has been provided with a curved surface, but in recent years, the panel has become nearly flat. If the panel is made to be nearly flat in this way, and let the horizontal imaginary line passing through the center of the panel be the X axis,
Raster distortion becomes significant parallel to the X axis. In this state, the number of scanning lines per fixed area is different in each part of the screen.

When the panel has a shape close to a flat shape,
It is difficult to optimize the moire fringes by selecting one optimum value for the vertical pitch of the shadow mask as in the conventional case.

Conventionally, the value of the vertical pitch of the shadow mask is constant or the vertical pitch on the screen is constant to shorten the frequency at which the moire fringes are generated to make the moire fringes inconspicuous, but the vertical pitch is constant. Therefore, there is a problem that moire fringes are generated when the screen is displaced.

An object of the present invention is to reduce moire fringes that occur when the panel is formed into a shape close to a flat surface. In addition, it is to solve the problem of the generation of moire fringes due to the distortion of the raster on the screen, and to make the moire fringes dense due to the interference between the electron beam scanning lines of the color cathode ray tube and the slot hole joints of the shadow mask. That is to make the moire fringes inconspicuous.

[0016]

In order to achieve the above object, the present invention provides a color phosphor layer formed on the inner surface of a panel and a porous electrode for color selection which is spaced apart from the phosphor layer. A shadow mask is provided, an electron gun for generating three electron beams at the neck portion and projecting the electron beams toward the phosphor layer is loaded, and near the joint portion between the neck portion and the funnel portion. In a color cathode ray tube in which a deflection magnetic field region for deflecting each of the electron beams in both horizontal and vertical directions to draw a scanning raster on the screen is set, the electron beam passage hole of the shadow mask is a round hole or a slot. The electron beam passage holes are arranged in rows in the vertical direction, and the vertical pitch of the shadow mask is the central portion of the shadow mask, the peripheral portion in the horizontal (X-axis) direction, and the corners. Unlike respectively between the vertical pitch of the shadow mask is obtained by vertical pitch> horizontal peripheral portion vertical pitch of the central portion, and formation.

Further, the vertical pitch of the shadow mask is different between the central portion, the horizontal peripheral portion and the corner portion of the shadow mask, and the vertical pitch of the shadow mask is as follows: vertical pitch of corner portion> vertical pitch of central portion> It is formed with a vertical pitch in the peripheral portion in the horizontal direction.

Further, the diagonal effective diameter, which is the diagonal of the effective diameter of the effective screen of the panel, is V (mm), and 1/2 of the effective diameter long side is L.
(Mm), the height difference between the center of the effective diameter long side and the end of the effective diameter long side is h, and the equivalent radius of curvature of the effective surface boundary is R =
When defined as (L ² + h ² ) / 2h, the equivalent radius of curvature R
Is 1.5 (42.5V / 25.4 + 45) ≦ R, and the vertical pitch of the shadow mask is different between the central portion and the horizontal peripheral portion of the shadow mask. Is the vertical pitch of the central part> the vertical pitch of the peripheral part in the horizontal direction, or the vertical pitch of the corner part> the vertical pitch of the central part> the vertical pitch of the peripheral part in the horizontal direction.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the color cathode ray tube of the present invention will be specifically described with reference to Examples.

FIG. 1 is a schematic diagram showing a color cathode ray tube according to the present invention, in which 1 is a panel portion, 2 is a funnel portion, and 3 is a funnel portion.
Is a neck portion, 4 is a phosphor screen, 5 is a shadow mask structure, 6
Is a magnetic shield, 7 is a deflection yoke, 8 is a purity adjusting magnet, 9 is a center beam static convergence adjusting magnet, 10 is a side beam static convergence adjusting magnet, 11 is an electron gun, and B is an electron beam.

In the convergence adjustment (static convergence) of such a color CRT, the convergence of the two side beams is first obtained, and then the center beam and the convergence points of the side beams are concentrated.

FIG. 2 is a view of the shadow mask structure 5 as seen from the panel side. An imaginary line in the vertical direction passing through the center of the shadow mask is the X axis, and an imaginary line in the horizontal direction passing through the center of the shadow mask is the Y axis. The effective area 51 is the area where the image is displayed on the cathode ray tube.

FIG. 3 is a partial schematic view of a shadow mask of a color cathode ray tube showing an embodiment of the present invention, and is a partially enlarged view of FIG. In the figure, 12 is a slot hole through which the electron beam passes, 13 is a bridge portion connecting the slot holes 12 in the vertical direction, Pv is a vertical pitch of the shadow mask, and W is a width of the bridge portion.

In the figure, the slot holes of the shadow mask are arranged such that the slot holes adjacent to each other in the horizontal direction are vertically displaced by 1/2 of the vertical pitch Pv.

FIG. 4 shows an image projected on the screen effective surface of the front surface of the panel, and particularly shows distortion of the image, which is obtained when a grid-like (called cross hatch) image pattern is projected. Only horizontal lines are displayed. This distortion has a barrel shape near the X axis (long axis) of the screen and a pincushion shape near the top and bottom of the screen.

In the figure, 14 is a screen central area in the screen effective surface, 15 is a screen peripheral area on the X axis in the screen effective surface, 1
6 is a screen corner area in the screen effective surface, 17 is a locus of scanning lines, and 18 is a screen effective diameter height.

As shown in FIG. 4, since the raster of scanning lines is distorted differently in the effective area of the screen, the number of scanning lines per given area is the center of the screen 14 and the peripheral part 1 of the screen on the X axis.
5. The screen corner section 16 is different from each other, and the relationship of screen corner section <screen center section and screen center section <screen peripheral section on the X axis is established.

Therefore, the vertical pitch of the shadow mask for optimizing the moire fringes is different in each area, and the relationship with the vertical pitch of the screen center is as follows: screen corner> screen center, screen center> X axis Moire fringes can be made inconspicuous by setting the relationship of the peripheral part of the screen above.

At this time, from the center of the screen to the periphery of the screen on the X axis, from the center of the screen to the corner of the screen,
Moreover, since the raster of the scanning line is gradually distorted from the peripheral portion of the screen on the X-axis to the corner portion of the screen, it is better to gradually change the vertical pitch on the shadow mask or the screen.

For example, the ratio (aspect ratio) of the long side to the short side of the screen effective surface is about 16: 9, the height 18 of the screen effective surface is 372.6 mm, and the number of scanning lines in the screen effective surface is about 450. At, the interval of electron beam on the phosphor screen is
The screen central portion 14 has 450 lines / 372.6 mm, the screen peripheral portion 15 on the X axis has 460 / 372.6 mm, and the screen corner portion 16 has 430 / 372.6 mm. That is, the apparent scanning lines in each area per unit area are different, the number of scanning lines becomes the coarsest in the screen corner portion where the electron beam spacing is wide, and then the screen central portion,
The periphery of the screen on the X axis is the densest.

In FIG. 5, the screen effective surface height 18 is 372.6.
It is a figure which showed the relationship of the vertical pitch of a fluorescent screen, the number of scanning lines in a screen effective surface, and a moire fringe of mm. Reference numeral 19 is a line showing the allowable limit vertical pitch of the moire fringes at each scanning line number, and 20 is a line showing the best inconspicuous value of the moire fringes at each scanning line number.

From FIG. 5, the optimum solution of the vertical pitch in which the moire fringes are not noticeable in each area on the phosphor screen is 1.1 mm in the central part of the screen, 1.08 mm in the peripheral part of the screen on the X axis, and the screen corner part. Is 1.16 mm.

By forming the vertical pitch of the shadow mask in this way, the horizontal lines when a grid pattern is projected on the screen of the panel are barrel-shaped near the major axis of the screen and are displayed above and below the screen. With respect to a CRT with a pincushion-shaped raster distortion, moire fringes can be made inconspicuous in each region.

By changing the vertical pitch on the shadow mask or on the screen as described above and forming the vertical pitch of the shadow mask as follows: screen corner section> screen center section, the screen corner section and the screen center section respectively Conspicuous moire fringes can be suppressed, and by forming the screen center part> the screen peripheral part on the X-axis, the moire fringes can be suppressed respectively in the screen center part and the screen peripheral part, and the screen corner part> screen By forming the center portion> the peripheral portion of the screen on the X-axis, the moire fringes can be optimized by suppressing the conspicuousness of the moiré fringes due to the apparent difference in the number of scanning lines at various places on the screen.

FIG. 6 shows the shape of the panel portion 1, and 2
1 is the boundary of the effective surface of the short side or the long side of the panel, and h is the height difference between the center of the long side (effective diameter long side) of the effective surface of the panel surface and the end of the effective diameter long side. , The effective screen is within the boundary of the effective surface. The lower the height difference h of the panel surface, the more the front surface of the panel looks like a flat shape.

Effective surface boundary portion 2 on the short side or the long side of the panel
1, the equivalent radius of curvature R (m
m), the diagonal of the effective diameter of the screen effective surface of the panel is the diagonal effective diameter V (mm), 1/2 of the long side of the effective diameter is L (mm), the central portion of the effective diameter long side and the effective diameter length. When the height difference from the end of the side is h and the equivalent radius of curvature is defined as R = (L ² + h ² ) / 2h, the equivalent radius of curvature R is 1.5 (42.5V / 25.
By making the shape satisfying 4 + 45) ≦ R, an apparently flat screen can be realized.

In a cathode ray tube having such a panel, the shadow mask or the vertical pitch on the screen is formed such that the screen center portion> the screen peripheral portion on the X axis, so that the screen center portion and the screen peripheral portion respectively have moire. Conspicuous stripes can be suppressed. Further, by forming the screen corner portion> the screen center portion, it is possible to suppress the moire fringes from being conspicuous in the screen corner portion and the screen center portion respectively. Therefore, the screen corner portion> the screen center portion> X
By setting the screen peripheral portion on the axis, the conspicuousness of moire fringes due to the apparent difference in the number of scanning lines at various places on the screen is further suppressed, and a high quality image can be realized.

Further, FIG. 7 shows a partial schematic view of an effective surface portion of a shadow mask having an electron beam passage hole having a round hole shape, and 22 is an electron beam passage hole of the shadow mask, Pv1.
Is the vertical pitch of the shadow mask. As can be seen from FIG. 7, the electron beam round hole shadow masks are arranged in rows in the vertical direction, and the positions of the round holes in adjacent rows are Pv1.
It is displaced by 1/2 of the above.

By setting the vertical pitch on the shadow mask or the fluorescent screen in the shape of a round hole such that the screen corner portion> the screen center portion, the moire fringes are suppressed in the screen corner portion and the screen center portion, respectively. By setting the screen center part> the screen peripheral part on the X axis, the moire fringes can be suppressed from being conspicuous in the screen central part and the screen peripheral part, respectively, and the screen corner part> the screen central part> the screen on the X axis. By setting the peripheral portion, the moire fringes can be optimized by suppressing the conspicuousness of the moire fringes due to the apparent difference in the number of scanning lines at various places on the screen.

[0040]

According to the present invention having such a configuration, the optimum value of the vertical pitch is defined in each region within the effective screen in accordance with the apparent number of scanning lines displayed on the image display surface. The moire fringes can be suppressed from being conspicuous in the area, and thus an excellent image can be obtained over the entire screen.

[Brief description of drawings]

FIG. 1 is a sectional view of a color cathode ray tube according to the present invention.

FIG. 2 is a plan view of a shadow mask structure of a color cathode ray tube according to the present invention.

FIG. 3 is a plan view of an essential part of a shadow mask of a color cathode ray tube according to the present invention.

FIG. 4 is a schematic diagram showing distortion of a raster on a screen of a color cathode ray tube according to the present invention.

FIG. 5 is a diagram showing the relationship between the vertical pitch of the fluorescent screen, the number of effective in-plane scanning lines, and moire fringes of the color cathode ray tube according to the present invention.

FIG. 6 is a perspective view showing a shape of a panel portion of the color cathode ray tube according to the present invention.

FIG. 7 is a partial schematic view of an effective surface portion of a shadow mask having a round hole-shaped electron beam passage hole which is another embodiment of the color cathode ray tube according to the present invention.

[Explanation of symbols]

 1 Panel Part 2 Funnel Part 3 Neck Part 4 Fluorescent Screen 5 Shadow Mask 51 Shadow Mask Effective Area 7 Deflection Yoke 11 Electron Gun 12 Slot Hole 13 Slot Hole Connecting Portion 14 Screen Central Area in Screen Effective Surface 15 Screen Effective Area Peripheral area of the screen on the X-axis 16 Screen corner area in the effective surface of the screen 17 Trajectory of the scanning line 19 Line showing the allowable vertical pitch of the moire fringes 20 Line showing the inconspicuous best value of the moire fringes 21 Effective surface boundary Part Pv Vertical slot period interval

Claims (6)

[Claims] 1. A color phosphor layer is formed on an inner surface of a panel, a shadow mask, which is a porous electrode for color selection, is arranged apart from the phosphor layer, and three electrons are provided in a neck portion. An electron gun for generating a beam and projecting it toward the phosphor layer is loaded, and each electron beam is deflected in both the horizontal and vertical directions near the junction between the neck portion and the funnel portion. In a color cathode ray tube in which a deflection magnetic field region for drawing a scanning raster is set, the shadow mask has a slot-shaped electron beam passage hole, and the vertical pitch of the shadow mask is the central portion of the shadow mask. , Different in the horizontal direction,
The above-mentioned vertical pitch is a vertical pitch of a central portion> a vertical pitch of a peripheral portion in a horizontal direction, which is a color cathode ray tube. 2. The vertical pitch of the shadow mask is different between the central portion, the horizontal peripheral portion, and the corner portion of the shadow mask, and the vertical pitch is corner vertical pitch> vertical pitch of central portion> horizontal direction. The color cathode ray tube according to claim 1, wherein the color cathode ray tube has a vertical pitch. 3. The diagonal of the effective diameter of the panel is V (mm),
One half of the long side of the effective diameter is L (mm), the height difference between the center of the long side of the effective diameter and the end of the long side of the effective diameter is h, and the equivalent radius of curvature of the effective surface boundary is R = ( When defined as L ² + h ² ) / 2h, the equivalent radius of curvature R is 1.5 (42.5V / 25.
The color cathode ray tube according to claim 1, wherein the color cathode ray tube has a shape satisfying 4 + 45) ≦ R. 4. The color cathode ray tube according to claim 2, wherein the aspect ratio of the panel effective screen of the cathode ray tube is about 16: 9. 5. The electron beam passage holes of the shadow mask are round holes, and the electron beam passage holes of the round holes are arranged in rows in a vertical direction. The color cathode ray tube according to the item. 6. A horizontal line when a grid pattern is projected on the screen of the panel is barrel-shaped near the major axis of the screen and pincushion-shaped above and below the screen. The color cathode ray tube according to claim 1 or 2.