JPH07272637A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To optimize a Moire fringe in many types of screen display mode by setting the vertical slit pitch of a shadow mask within a specific range for measuring area diameter on the shadow mask. CONSTITUTION:The slits 51 of a shadow mask have a vertical pitch Pv larger than the vertical pitch of the conventional shadow mask and set within the range of 0.5 to 2% of a shadow mask measuring area diameter. Also, the slits 51 are arranged in a vertical direction via slit tie sections 52, and slits 51' adjacent to the slits 51 in a horizontal direction are arranged at the vertical displacement of 1/2 of the vertical pitch Pv. According to this construction, a shadow mask type color cathode-ray tube with a hardly visible Moire fringe within a wide variable range of conventionally unavailable scanning lines exceeding 100 can be provided, when the vertical pitch Pv is enlarged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube used for color image display, and more particularly to improvement of a shadow mask in a shadow mask type color cathode ray tube.

[0002]

2. Description of the Related Art A color cathode ray tube used for displaying a color image is composed of a panel portion which is an image screen, a neck portion which accommodates an electron gun, and a funnel portion which connects the panel portion and the neck portion. Is equipped with a deflection yoke for scanning an electron beam emitted from an electron gun on a phosphor screen coated and formed on the inner surface of the panel.

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. On the way from the electron gun to the fluorescent screen, the electron beam is deflected in the horizontal and vertical directions by the deflection yoke provided in the funnel portion, so that the electron beam is scanned over the entire fluorescent screen, and the shadow mask provided inside the panel. The image is formed on the phosphor screen by being color-selected by the above and impinging on the corresponding phosphor.

A problem of a color cathode ray tube having a shadow mask having a periodic slit array in the vertical direction is moire fringes caused by interference between electron beam scanning lines and slit hole period (shadow mask pitch).

It is impossible to eliminate the moire interference fringes, and the slit hole period of the shadow mask is set so that the moire fringes are not noticeable.

When the conventional horizontally adjacent slit holes 511 as shown in FIG. 6 are vertically displaced by 1/2 of the vertical slit hole period interval (vertical pitch) Pv1, the moire fringe period λ is , Analytically given by the following general formula.

Λ / V = 1 / ┃ {2 / (P / V) -mN
/ 2} ┃ (1) (m = 1,2,3 ...) where V is the vertical diameter of the shadow mask effective surface, P is the vertical pitch Pv1, N is the number of electron beam scanning lines in the effective surface, and m Indicates the moire fringe mode. When m is an odd value, moire fringes are generated only when the scanning lines are paired (or when non-interlaced).

In the conventional shadow mask type color cathode ray tube, the number of scanning lines in the effective display screen is about 450 in the NTSC system.
Since this is fixed at about 550 in the book and PAL system, the problem can be solved by determining one shadow mask pitch value in which moire interference fringes are hard to see.

FIG. 7 shows the moire fringe period λ of the above general formula (1).
Is an example shown in the figure, and shows the ratio of the vertical pitch Pv1 to the effective surface vertical diameter and the ratio of the moire fringe wavelength to the effective surface vertical diameter when the number of effective in-plane scanning lines is 450. Pmax (m) is the ratio of the most noticeable vertical pitch Pv1 of the moire fringes in each moire fringe mode m to the effective surface vertical diameter. As for the vertical pitch Pv1 of the conventional shadow mask type color cathode ray tube, it is generally difficult to see moire fringes at a position where the cycle is most dense. Therefore, in the vicinity of the intersection point Pmin (m) of the adjacent moire fringe modes m. Is used as the ratio of the vertical pitch Pv1 to the effective surface vertical diameter.

For example, the intersection Pmi of P (2) and P (3)
In n (2), Pmin (2) /V=0.36%, and Pmin
At the intersection Pmin (3) of (3) and P (4), Pmin
(3) /V=0.25%, and at the intersection Pmin (4) of P (4) and P (5), Pmin (4) /V=0.20%
The vertical pitch Pv1 of the shadow mask is determined by a value in the vicinity of. Moire fringes can be made inconspicuous by determining the value in the vicinity. Pmi, which is the intersection of P (m) and P (m + 1)
n (m) is calculated by the following general formula.

Pmin (m) / V = 8 / {(2m + 1)
· N} (2) (m = 1, 2, 3 ...) An example in which the vicinity of Pmin (1) corresponding to m = 1 in the general formula (2) is used due to the strength constraint of the shadow mask curved surface. There is no.

On the other hand, the position where the moire fringes are the coarsest is given by the following general formula, and the moire fringes are most noticeable at this position.

Pmax (m) / V = 4 / (m · N) (3) (m = 1, 2, 3 ...) As a related to the conventional shadow mask in which moire fringes are inconspicuous. , For example, Japanese Patent Publication Sho 55-1337
No. 1, JP-A-56-76144, JP-A-62.
-51135, JP-A-63-43241,
JP-A 1-161641 can be mentioned.

[0014]

Since the number of scanning lines in the effective display screen is almost fixed in the conventional color cathode ray tube as described above, the value of the shadow mask pitch is set to 1 in accordance with the number of scanning lines in the effective display screen. By deciding one, I was able to make moire fringes inconspicuous.

In recent years, the number of scanning lines in the effective display screen has been significantly changed with the diversification of display applications of color cathode ray tubes.
There have been cases where a large number of screen display modes (scan lines) are switched and used, but for such applications, many types of screens are used in the vicinity of the ratio of the vertical pitch of the conventional shadow mask to the vertical diameter of the effective surface. It is difficult to optimize moire fringes in display mode.

Further, a method of making the vertical pitch extremely small can be considered from the viewpoint of reducing the contrast of moire fringes as a whole, but there is a problem that the screen brightness (luminous efficiency) is lowered by increasing the area ratio of the slit hole connecting portion. There is a problem that it is technically difficult to form slit holes in the shadow mask.

An object of the present invention is to solve the problem that it is difficult to optimize the moire fringes in the various types of screen display modes that the above-mentioned conventional technique has.

Another object of the present invention is to reduce the occurrence of moire fringes due to the interference between the electron beam scanning lines of the color cathode ray tube and the slit hole connecting portions of the shadow mask, and at the same time improve the luminous efficiency of the screen.

[0019]

In order to achieve the above object, the present invention provides a color cathode ray tube provided with a shadow mask having slit holes, in which the vertical pitch of the shadow mask is relative to the effective surface vertical diameter on the shadow mask. 0.5% to 2.0%.

Also, the slit holes which are adjacent to each other in the horizontal direction of the slit holes arranged in the vertical direction of the shadow mask are arranged vertically displaced by 1/2 of the vertical slit hole period, and are arranged in the horizontal direction of the shadow mask. In a color cathode ray tube having a shadow mask in which the slit holes vertically adjacent to each other are horizontally displaced by 1/2 of the horizontal slit hole period, and the shadow mask has an aspect ratio of 16: 9. , The vertical pitch of the shadow mask is 0.
It is set to 5% to 2.0%.

[0021]

In the color cathode ray tube provided with the shadow mask having the slit holes as described above, the vertical pitch of the shadow mask is 0.
By setting it to 5% to 2.0%, the interference fringes due to the slit hole connecting portion of the shadow mask and the scanning line of the electron beam become inconspicuous, and the luminous efficiency of the screen of the color cathode ray tube is increased.

[0022]

EXAMPLES The color cathode ray tube of the present invention will be specifically described below with reference to examples.

FIG. 5 is a schematic diagram showing a color cathode ray tube of the present invention, in which 1 is a panel portion, 2 is a funnel portion, and 3
Is a neck portion, 4 is a fluorescent screen (screen), 5 is a shadow mask, 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, and 10 is a side beam static convergence adjusting magnet. , 11 are electron guns, and 12 is an electron beam.

FIG. 1 is a partial schematic view of a shadow mask of a color cathode ray tube showing an embodiment of the present invention. In the figure, the slit holes 51 of the shadow mask have a vertical pitch Pv.
Is longer than the vertical pitch Pv1 of the conventional shadow mask and 0.5% to 2.% of the vertical diameter of the shadow mask effective surface.
In the range of 0%, the slit holes 51 'arranged in the vertical direction via the slit hole connecting portion 52 and horizontally adjacent to the slit holes 51 are vertically displaced by 1/2 of the vertical pitch Pv. There is.

FIG. 2 is a partial schematic view of a shadow mask of a color cathode ray tube showing another embodiment of the present invention. In the figure, the slit holes 51 of the shadow mask have a vertical pitch P.
v is made longer than the vertical pitch Pv1 of the conventional shadow mask, and is arranged at 0.5% to 2.0% of the vertical diameter of the shadow mask effective surface. Further, in order to prevent the strength of the shadow mask surface from being lowered due to the decrease in the number of slit hole connecting portions in the vertical direction, the slit holes 5 adjacent to each other in the vertical direction are formed.
1 ″ are arranged in the horizontal direction with a shift of 1/2 of the horizontal slit period interval (lateral pitch) Ph of the shadow mask.

FIG. 3 is a schematic view of a shadow mask. A vertical axis L1 of the shadow mask effective surface is on the minor axis, a horizontal diameter L2 of the shadow mask effective surface is on the major axis, and a diagonal diameter L3 of the shadow mask effective surface is diagonal on the effective surface. I have taken it.

In the figure, the aspect ratio (horizontal to vertical ratio of the screen) is 16: 9, and the diagonal dimension of the effective screen is 56 cm.
(24 type) L for shadow mask for color cathode ray tube
1 = 259.24 mm, L2 = 447.02 mm, L3
= 516.8 mm, the vertical pitch Ph is 0.87 of L1.
By taking 75%, it is possible to obtain 2.275 mm, and at this time, the vertical length of the slit hole 51 is 2.1.
45 mm, the width of the slit hole 51 in the horizontal direction is 0.190
mm. By doing so, moire fringes can be reduced, and light emission efficiency can be improved.

The various slit hole periods (pitch) and the generation state of moire fringes in the screen display mode are Pmin (m) to Pmax corresponding to the odd-numbered order of the moire fringe mode m.
It was confirmed by an experiment that (m) was relatively unnoticeable.

FIG. 4 shows the odd-numbered orders of m in the range of the optimum vertical pitch Pv according to the number of scanning lines in the effective surface, where the vertical axis represents the ratio of the vertical pitch Pv to the effective surface vertical diameter L1 and the horizontal axis. Is the number of effective in-plane scanning lines.

In the figure, when the region S in which moire fringes in which m = 3 or more is inconspicuous is selected, the vertical pitch Pv is set as follows.
It can be seen that the range of the number of scanning lines is narrow and limited.

On the other hand, when the vertical pitch Pv is longer than that of the conventional shadow mask in which the vertical pitch Pv exceeds 0.5% of the effective surface vertical diameter L1, the scanning is performed by using the area S where the moire fringes of m = 1 are inconspicuous. Moire fringes can be reduced over a wide range of lines.

From the strength of the shadow mask curved surface, the upper limit of the vertical pitch Pv is preferably set to 2.0% of the effective surface vertical diameter L1.

In the same figure, a straight line A shows the number of effective in-plane scanning lines when the ratio of the vertical pitch Pv to the effective surface vertical diameter L1 is about 0.9%. It is a value that makes moire fringes inconspicuous in the range of 450 lines, and the luminous efficiency is increased by 10%. A straight line B indicates the number of effective in-plane scanning lines when the ratio of the vertical pitch Pv to the effective surface vertical diameter L1 is about 0.6%. 450 to 6
It is a value that can make moire fringes inconspicuous in the range of 00 or more.

The vertical width of the vertical slit connecting portion does not necessarily have to be increased in proportion to the vertical pitch Pv. Therefore, by increasing the length of the vertical slit hole, the transparency of the electron beam to the shadow mask is increased, the luminous efficiency of the fluorescent screen of the color cathode ray tube is improved, and the luminous efficiency of the present invention is relatively increased by 6% to 17%. Extends to

In the above embodiment, the case where the holes of the shadow mask have a slit shape elongated in the vertical direction has been described, but the present invention is not limited to this. For example, a rectangular shape, a polygonal shape, a circular dot Shape), a non-circular dodd shape, or the like.

[0036]

According to the present invention, by increasing the vertical pitch, the variable range of the scanning line, which has been impossible in the past, is reduced to 10.
It is possible to obtain a shadow mask type color cathode ray tube in which moire fringes are hardly visible in a wide range of zero or more.

Further, the contrast of the moire fringes generated by the reduction of the area ratio of the vertical slit connecting portion is weakened, and at the same time, it contributes to the improvement of the luminous efficiency of the fluorescent screen of the color cathode ray tube and the utilization efficiency of the electron beam is improved. The current value of the electron beam used in the conventional color cathode ray tube is often used in the maximum range that can be used in terms of performance other than screen brightness. Therefore, the effect of increasing the luminous efficiency is quite useful.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a shadow mask of a color cathode ray tube showing an embodiment of the present invention.

FIG. 2 is a plan view of a main part of a shadow mask of a color cathode ray tube showing another embodiment of the present invention.

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

FIG. 4 is a characteristic diagram relating to the ratio of the slit hole period to the effective surface vertical diameter and the number of effective in-plane scanning lines.

FIG. 5 is a cross-sectional view showing a schematic configuration of a color cathode ray tube according to the present invention.

FIG. 6 is a plan view of a main part of a conventional shadow mask.

FIG. 7 is a characteristic diagram regarding a ratio of a moire wavelength to a vertical diameter of an effective surface and a ratio of a slit hole period to a vertical diameter of the effective surface.

[Explanation of symbols]

 1 Panel Part 2 Funnel Part 3 Neck Part 4 Fluorescent Surface 5 Shadow Mask 51,511 Slit Hole 52,521 Slit Hole Joint Pv, Pv1 Vertical Slit Period Interval Ph Horizontal Slit Period Interval L1 Shadow Mask Effective Surface Vertical Diameter L2 Shadow Mask effective surface horizontal diameter L3 Shadow mask effective surface diagonal diameter 6 Inner shield 7 Deflection yoke 11 Electron gun

Claims (4)

[Claims] 1. A screen of color phosphor is formed on an inner surface of the face plate, which includes an evacuated envelope including a face plate portion, a neck portion, and a funnel portion connecting these portions to each other. A shadow mask, which is a porous electrode for color selection, is arranged apart from the screen, and an electron gun for generating three electron beams at the neck portion and projecting the electron beams toward the screen is loaded. Further, 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 near the junction between the neck portion and the funnel portion. In the present color cathode ray tube, the vertical slit hole period of the shadow mask is 0.5% to 2 with respect to the effective surface vertical diameter on the shadow mask. .0
% Cathode ray tube. 2. The slit holes, which are adjacent to each other in the horizontal direction of the slit holes arranged in the vertical direction of the shadow mask, are arranged so as to be displaced in the vertical direction by ½ of the vertical slit hole period. The color cathode ray tube according to claim 1. 3. The slit holes vertically adjacent to the slit holes arranged in the horizontal direction of the shadow mask are arranged so as to be displaced in the horizontal direction by 1/2 of the horizontal slit hole period. The color cathode ray tube according to claim 1. 4. The aspect ratio of the shadow mask is 1.
The color cathode ray tube according to claim 1, wherein the color cathode ray tube is 6: 9.