JPS61214332A - Color video tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a cathode ray emitting line screen (
The invention relates to a color picture tube of the type having a perforated shadow mask in the form of slit holes mounted close to a screen on which phosphors are formed in stripes, and in particular an improved contour shape of the mask. The present invention relates to improving the spacing of the mask aperture rows in the picture tube so as to obtain the above-mentioned picture tube.

BACKGROUND OF THE INVENTION Most color picture tubes currently manufactured are of the line-screen-slit mask format. These picture tubes include a rectangular face plate with a spherical profile and a line screen made of cathodoluminescent material, and a slit-opening shadow mask with a spherical profile adjacent to the screen. There is. The slit-type apertures in such picture tubes are arranged in rows substantially parallel to the short axis of the tube, or have progressively increasing curvature from the center of the mask toward the short sides.

In recent years, several partially modified color picture tubes have been proposed. One such modification is the idea of a new faceplate panel profile that has a planar appearance effect. Such picture tube modifications are described in U.S. Patent Application No. 469, filed February 25, 1983.
．． No. '7'72 (Japanese Patent Application No. 59-34113, Japanese Unexamined Patent Publication No. 5
Corresponding to No. 9-163737) and No. 469,774 (Japanese Patent Application No. 59-31321, Japanese Unexamined Patent Publication No. 59-16373)
(corresponding to No. 8).

The modified tube faceplate profile has curvature along both the major and minor axes of the faceplate panel, but is not spherical. The major and minor axes are defined as the central horizontal axis and central vertical axis, respectively, when the tube is placed in its normal viewing position. In the preferred embodiments shown in the above-mentioned applications, the peripheral border of the tube screen is substantially flat and visually appears flat. To obtain this flat or substantially flat peripheral border, make the faceplate panel a curvature along its long axis: in the center of the panel.

It should be made larger at the sides of the panel than at the edges. Such aspherical shapes for faceplate panels create problems involving shadow mask contours. If the shadow mask is formed along its sides with a straight cross-section parallel to the minor axis, the mechanical properties of the mask will be degraded and undesirable microphonics and doming problems will occur. Therefore, in these cross sections, it is desirable to form the mask with a greater curvature than that indicated by the profile shape of the faceplate panel. However, this change in the mask profile requires other changes to be made to the tube, including changes in the aperture pattern of the mask.

In early line screen-slit mask type tubes, the shadow mask was nearly spherical, and the spacing (horizontal separation) between adjacent rows of apertures along its long axis remained constant throughout the mask. However, later versions of this type of tube were published in U.S. Pat.
, 136.300, using a shadow mask with increased curvature and varying spacing of aperture arrays. In these later tubes, the distance between the centerlines of adjacent rows of apertures increases from the center of the mask toward the edges. The rate of this increase varies along the major axis approximately as the square of the distance from the minor axis.

U.S. Patent Application No. 615, 5, dated May 31, 1984.
No. 89 (Japanese Patent Application No. 118685, 1982, Japanese Patent Application No. 1986-2)
(Corresponding to No. 62335), the specification discloses a novel distance between rows of apertures. In this patent application, the distance between adjacent rows of apertures increases from the center of the shadow mask to the sides as approximately the fourth power of the distance from the minor axis of the shadow mask. This change in the distance between columns is expressed as the product of a certain coefficient and the fourth power of the distance, and the above coefficient applies to a cross section of the mask parallel to the central horizontal axis and further away from it, rather than for a cross section on the central horizontal axis. It is changing to become larger. This fourth power variation has proven sufficient for early era substantially flat tube shadow mask profiles. These early-era tubes have a shadow mask that has substantially more curvature along its short axis than along its long axis. However, the curvature of the mask in cross-section parallel to the short axis decreases from the short axis to the sides of the mask, where it is relatively flat. This flatness is
It is not preferred as a shadow mask because it is susceptible to deformation during processing and undergoes some unpredictable deflection when heated during operation of the tube. The present invention improves the distance between the rows of apertures in order to obtain a trade-off between various curvatures in such a shadow mask in order to increase the curvature on the sides of the mask. This is an improved version.

SUMMARY OF THE INVENTION In accordance with the present invention, a substantially rectangular cathodoluminescent line screen is provided with
In a color picture tube having a shadow mask with generally rectangular slit apertures, the distance between adjacent aperture rows near the short axis of the mask is smaller near the long side of the mask than near the long axis of the mask. has been improved.

Description of preferred embodiments Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a rectangular color picture tube 10 having a glass envelope 11 consisting of a rectangular faceplate panel 12 and a tubular neck 14 connected by a fan/L/16. The spring /l/12 consists of a viewing face plate 18 and a peripheral flange or side wall 2o sealed to the funnel 16 by a glass frit 17.
, on the inner surface of the face plate 18 is a new rectangular 3
A color cathodoluminescent phosphor screen 22 is formed.

The screen is a line screen, with the short axis of the tube Y-Y (
Perpendicular to the plane of Figure 11), there is a line of phosphor extending parallel to the plane. The contour shape of the phosphor line will be described in detail below. Face plate spring/l/
A novel porous color selection electrode or shadow mask 24 is removably mounted within 12 at a predetermined distance from screen 22. In FIG. 1, an in-line electron gun 26, shown schematically by a line,
4, it generates and directs three heptad beams 28 along a coplanar convergence path that initially passes through the mask 24 and reaches the screen 22.

The tube 10 of FIG. 1 is designed for use with an external magnetic deflection yoke, such as yoke 30 shown schematically surrounding the neck 14 and funnel 16 near the junction thereof, and includes three beams. Applying vertical and horizontal magnetic fields to 28, these beams are aligned horizontally in the direction of the major axis (X-X) and vertically in the direction of the minor axis (Y-Y) in a rectangular raster on the screen 22. scan each.

FIG. 2 is a front view of the face plate spring (v12). The periphery of the spring/L'12 is formed into a rectangle with slightly curved sides. The boundaries of the screen 22 are indicated by dotted lines in FIG. 2, and the boundaries of this screen are rectangular.

A comparison of the relative contours of the outer surface of the faceplate spring (v12) along the short axis Y-Y and the long axis xx is shown in FIG. The outer surface of the faceplate spring/l/12 is curved along both the major and minor axes and the panel 12
The curvature along the short axis at the center of is also larger than the curvature along the long axis. For example, at the center of the faceplate, the ratio of the radius of curvature of the outer surface profile along the major axis to the radius of curvature of the outer surface profile along the minor axis is greater than 1.1 (1
greater than 0% difference). However, the curvature along the long axis is smaller in the center of the faceplate and significantly larger near the edges of the faceplate. In this embodiment, the curvature along the major axis near the edge of the faceplate is greater than the general curvature along the minor axis. According to this design, the center of the faceplate is flat, while the points on the outer surface of the faceplate at the edges of the screen are substantially in the same plane P, forming a substantially rectangular peripheral contour. Limited. The curvature of the surface along the diagonal is chosen to clarify the change between different curvatures along the major and minor axes. At the center of the faceplate, the curvature along the short axis is approximately 4/3 greater than the curvature along the long axis.

By using different curvatures along the major and minor axes,
Points on the outer surface of the panel directly opposite the edges of the screen 22 lie on substantially the same coplanar plane P. These substantially coplanar points are located on the screen 2 when viewed from the front of the face plate spring μm2 as shown in FIG.
forming a contour on the outer surface of a substantially rectangular panel superimposed on the ends of two. Accordingly, when the tube 10 is inserted into a television receiver, a border mask of uniform width or a beveled edge frame may be used around the tube. The edges of such edges that contact the tube in the rectangular contour also lie substantially in the same plane P. The peripheral border of the image on the tube screen appears flat, creating the effect that the image appears flat even though the faceplate panel is curved outward along both the major and minor axes. It will be done.

FIG. 4 shows the front side of the new shadow mask 24. The dark lines 32 indicate the boundaries of the apertures in the mask 24. mask 24
The contours of the surface along the long axis XX, the short axis Y-Y, and the diagonal are shown by curves 5a, sb, and 5c in FIG. 5, respectively. Mask 24 is along its short axis υ
also have different curvatures along their long axes. The profile along the long axis has a slight curvature near the center of the mask and a greater curvature at the sides of the mask. The contour of such a shadow mask describes the curvature of the long axis x-x with a large radius circle centered approximately at the central portion of the long axis and a smaller radius circle throughout the remainder of the long sleeve. You can get it by doing this. More specifically, however, the sagittal height along the major axis varies substantially as the fourth power of the distance from the minor axis Y--Y. The sagittal height is the distance from a virtual plane that is tangent to the center of the mask surface. The curvature parallel to the short axis Y-Y is shaped to smoothly match the curvature of the long sleeve to the required mask perimeter and can include the same curvature changes used along the long axis. . Since the contour shape of such a mask has a large curvature at the axial end, the thermal expansion characteristics are improved to some extent. The improvement of the coefficient of thermal expansion by increasing the curvature is discussed in the aforementioned U.S. Pat. No. 4,136.
, 300.

FIG. 6 shows the distance AH between the aperture rows in the quadrant of the shadow mask 24 by a solid curve and symbol H, and is constructed as shown in the above-mentioned U.S. Patent Application No. 615,589. The following graph shows the distance AH between the aperture rows in the quadrant of the shadow mask with a dotted line and symbol F. The ordinate of the graph indicates distance from the major axis. The abscissa indicates the distance between the rows of apertures, measured between the centerline of one row and the centerline of an adjacent row, as shown in FIG. Each curve is labeled with a numerical value representing its distance from the minor axis. For example 200
Each curve marked with ! It represents the distance between the 1200th and 201st holes.

In conventional masks, shown by dashed lines, the distance between the rows of apertures is uniform along the short axis near the short axis, as shown by lines "F"-1 and "F"-150. ”
The straight curve labeled F'-200 has an interval of 200
The distance between the columns increases slightly with distance from the long axis. Curve “F”-3 which is substantially curved downward
00 and "F"-306 indicate that the distance between columns increases considerably with increasing distance from the long axis.

The distance between the aperture rows of the new improved shadow mask is significantly different from that of the conventional mask near the minor axis.1 As shown in Figure 6, the distance between the aperture rows near the minor axis The inter-column distance AH is determined by the curves "H"-1, "H"-50, "
It decreases with increasing distance from the major axis, as shown by H"-100. Near the 150th interval, the distance between the aperture rows decreases as shown by the slightly sloping curve "H"-150. As the distance from the long axis increases, it begins to increase slightly.

This curve showing the distance between the rows of holes is the curve "H"
-200 and H″-300 increases with increasing distance from the minor axis, but the curve “H″-305
As can be seen by comparing the curve "H"-300'i with the mask, the distance between the aperture rows along the long axis decreases slightly on the sides of the mask, and the distance from the short axis is equal to the 4th power of is increasing as a function of In the particular embodiment shown in Figure 6, this change in major axis is expressed in units of mils as MAH = 30 + 0.0
0185χ4 (AH = '76 in microns)
2 + 0.00185χ4).

However, as we move away from the long axis, the change in the distance between the aperture rows becomes more complex, and AH
== a + bz" + Ox'. Here, a%'b
.

C is a different function of the square of the distance from the major axis, and χ is the distance from the minor axis.

The screen 22 of W 10 is constructed in a well-known photographic process using a shadow mask 24 as a photographic mask. A problem arises when using linear light sources in the exposure step of photographic processing. This problem is due to the misalignment of the linear light source image and the centerline of the phosphor line. This misalignment, also referred to as "skew error," causes the distribution of light intensity used to print the phosphor line to be wider, thereby increasing the susceptibility of the phosphor width to the light exposure. The line width becomes thicker, making it more difficult to control the line width. In the prior art, the exposure of several screen areas in sequence and the tilt of a linear light source are synchronized, for example as shown in U.S. Pat. No. 3,888,673 dated June 10, 1975. area exposure technology, and June 1975
This skew can be eliminated by various methods, such as techniques for bending the aperture arrays and phosphor lines downward, as shown in U.S. Pat.
Compensation for errors was made. In the novel picture tube 10, the skew problem is solved by varying the distance between the rows of apertures as a function of both the distance from the short axis and from the long axis. As a result, the pattern of phosphor lines becomes a curved line in the area of the screen where the skew error is greatest, and a straight line on the sides of the screen where the skew error of this tube is minimized. Such a pattern is shown in FIG. In the same figure, the actual M40
45 represent the phosphor lines of selected spacing, and the dotted line 46 represents the line IIA parallel to the minor axis. As is clear from the figure, the curvature of the phosphor line increases with increasing distance from the minor axis from line 42 to the maximum curvature in the vicinity of line 43, after which the curvature decreases until the final straight line 45. are doing.

Using this new distance between the aperture rows allows the use of a shadow mask with a larger curvature in the cross section near the side of the mask parallel to the minor axis than would otherwise be possible. There is an advantage to it. The profile of the faceplate panel with substantially flat edges is indicative of the profile of the mask as indicated by edge 50 in FIG. Line 50 shows the contour on mask 52 of equal sagittal height. As can be seen, line 50 is substantially straight at both the left and right ends of the mask. This linearity creates major problems in mask formation and processing. For example, just touching the mask slightly causes it to curve inward during normal processing.

Therefore, in order to prevent such problems from occurring,
It is desirable to design the mask so that the curvature of both sides thereof is large. Using the new aperture row spacing results in an improved mask profile as shown by line 54 in FIG. This line 54 represents the contour of equal sagittal height on the mask 56. In this case, line 54
is considerably curved on the left and right sides of the mask, which allows for greater curvature parallel to the short axis and therefore greater strength.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing most of the shadow mask picture tube in cross section according to an embodiment of the present invention, and FIG. 2 is a face plate of the color picture tube seen in the direction of line 2--2 in FIG. A front view showing the front side, FIG. 3 shows the surface contour shape of the faceplate panel in the major axis 3a-3a of FIG. 2 and the surface contour shape of the faceplate panel in the minor axis 3b-3b superimposed. 4 is a front view of the shadow mask of the color picture tube shown in FIG. 1, and FIG. 5 shows the long axis 5a-5a and short axis 5 of the shadow mask of FIG.
b −5b, and diagonal 5C! In FIG. 6, which shows the surface contour shapes of the cross section at -50, the solid line indicates the distance between the aperture rows of the color picture tube mask according to the present invention, and the dotted line indicates the distance between the aperture rows of the conventional mask. Figure 7 shows the shadow graph of the area surrounded by circle 7 in Figure 4.
An enlarged view of the mask; FIG. 8 shows a graph of selected screen lines of a color picture tube; FIG. 9 shows a shadow mask showing contour lines of constant sagittal height indicated by the curvature of the faceplate. FIG. 10 is a front view of an improved shadow mask showing contour lines of constant sagittal height. 1.0...Color picture tube, 22...Screen, 2
4...Shadow mask, X-X...Long axis, Y-
Y...Short axis.

Claims (1)

[Claims] (1) a shadow mask mounted adjacent to a cathodoluminescent line screen, the shadow mask having a plurality of slit-like apertures arranged in rows, two opposite long sides; a substantially rectangular periphery with two opposing short sides, the long axis of the mask being an axis extending through the center of the mask and through the center of the short sides; The short axis of the mask is an axis extending through the center of the mask and the center of the long side, and the rows of openings generally extend in the short axis direction and are spaced apart from each other in the long axis direction. A color picture tube, wherein the distance between the aperture rows near the short axis of the mask is smaller near the long side of the mask than near the long axis of the mask.