JPS641898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a cathode ray tube comprising a cathode ray-excited linear fluorescent display screen and a porous shadow mask having a slit-like opening spaced from the display screen and installed in the tube. In particular, the present invention relates to a cathode ray tube having a visually improved display surface with smooth contour lines.

Recent cathode ray tubes developed and sold for color television have a spherical rectangular face plate with a linear fluorescent display surface excited by cathode rays on the inside, and a spherical thin face plate adjacent to the display surface. and a gap-like aperture shadow mask. The slot-like apertures of a shadow mask (hereinafter sometimes simply referred to as mask) are arranged in parallel vertical rows, each row containing a plurality of slot-like apertures separated vertically by a strip of the mask. Contains. The strips in adjacent rows are vertically staggered. In this way, the strips are staggered vertically in each row, and each slit-like opening is generally kept at a constant length, so the upper and lower contour limit lines of the shadow mask are mainly arranged in each row. It passes through an aperture in it, but often also through a band. If one row touches the contour limit line with a strip, and another column touches the contour limit line with an aperture, then
A step is added to a certain part of the upper and lower contour limit lines of the display surface,
This step is aesthetically undesirable because it is visible to viewers sitting close to the display screen.

The cathode ray tube according to the present invention has a cathode ray excitation type linear fluorescent display screen and a slit-like aperture shadow mask installed within the tube at a distance from the display surface, and the slit-like apertures of the mask are substantially are arranged in parallel rows. Additionally, the slot-like apertures in each row are vertically separated by strips of the mask. In the shadow mask used in this invention,
Some of the edges of the array of slotted apertures are modified to provide a visually improved display surface without steps at the top and bottom edges of the display surface.

Hereinafter, a detailed description will be given with reference to the accompanying drawings.

FIG. 1 shows a rectangular color picture tube having an evacuated glass envelope 20 consisting of a rectangular panel 22, a funnel portion 26 and a tubular neck portion 24. As shown in FIG. An internal view of the panel is shown in Figure 2. The panel 22 consists of a viewing faceplate 28 and a peripheral flange or sidewall 30 sealed to the funnel 26. The inner surface of the faceplate 28 is provided with a mosaic tricolor cathodoluminescent linear fluorescent display surface 32 having rows of phosphor lines extending substantially parallel to the vertical axis (y-y) of the tube. The space between each phosphor may be filled with a light-absorbing material. A porous color selection electrode, ie, a shadow mask 34 (not shown), is detachably attached to the inside of the panel 22 at a predetermined distance from the display surface 32. The shadow mask 34 has a number of slot-like apertures arranged in substantially parallel vertical rows, each row containing a plurality of slots separated vertically by bands in the shadow mask. Contains pores. The strips in adjacent rows are vertically staggered so that when viewed from the side, the apertures form a regular brick-like pattern.

An in-line electron gun 3 is installed inside the network part 24.
6 (schematically shown) is attached, and three electron beams 38
B, 38R, and 38G are generated and directed to the display surface through the mask 34 along a concentrated path in the same plane.

An external magnetic deflection yoke 40 is provided in the vicinity of the joint between the neck portion 24 and the funnel portion 26 of the picture tube shown in FIG. When an appropriate current is applied to the deflection yoke 40, the three electron beams 38B, 38R, and 38G are vertically and horizontally deflected by the action of vertical and horizontal deflection magnetic fields to form a rectangular raster on the display surface 32. For simplicity, FIG. 1 does not show the actual curvature of the path of the deflected electron beam in the deflection region, and the electron beam is directed to the deflection plane P-
It is schematically shown as being bent instantaneously at P.

FIG. 3 shows an enlarged view of a portion of the panel 22 indicated by circle 4 in FIG. 2 in a conventional picture tube. In FIG. 3, a portion of the shadow mask 42 is removed to expose a portion of the picture tube display surface 44. The shadow mask 42 has a plurality of slot-like openings 46 arranged in rows 48, and except for some slot-like openings 50 near the outer periphery of the shadow mask, all slot-like openings 46 are the same. It has length. Each slotted aperture 46 in each row 48 is separated from adjacent slotted apertures in the same row by a band 52 of substantially the same length as measured along the length of the row. . The center-to-center distance of adjacent strips 52 in the same row (ie, a length equal to the standard length slot-like aperture plus one strip) is referred to as the vertical strip repeat distance (WRD). This band repeat distance is maintained throughout the mask. Because of this repeating pattern of the bands, and because it is desired that the predetermined contour limits 88 of the display surface be parallel to the slightly curved top and bottom contours of the panel 22 and mask 42, the predetermined contour limits 88 are generally Cut slot-like apertures, but sometimes cut slot-like apertures at or close enough to the band to form a slot-like aperture pattern that is insufficient for complete etching. . The slotted aperture pattern that is not etched for such a pattern is shown by dashed lines 54 and 56 in FIG. Since the shadow mask 42 is also used as a photomaster when forming a fluorescent display screen, when a predetermined contour limit line 88 passes through or near the band-shaped portion, a display surface with irregular irregularities is formed near the upper and lower contour limit lines. That will happen. Since the incomplete slot-like aperture pattern 56 shown by the dotted line in FIG. It's finished.

Due to the unevenness of the upper and lower ends of the phosphor lines, irregular steps appear at the upper and lower ends of the display screen.
Not aesthetically pleasing.

In order to prevent the above-mentioned irregular steps from being formed at the upper and lower ends of the display surface, all the strips formed near the predetermined outline limit line 88 are eliminated, and the width of each column is reduced. The slit-like openings at the upper and lower ends may all terminate in contact with the predetermined contour limit line 88. Actually, in order to prevent the formation of a short slit-like opening pattern of 1/2 WRD or less in contact with the contour limit line 88, the center is located within 1/2 WRD from the predetermined contour limit line 88. All coming swaths will be discontinued. Then, as shown in the shadow mask 62 of FIG.
9 all end in contact with the predetermined contour limit line 88, so the display surface 70 formed based on this
The upper and lower ends of the screen form a smooth outline, and there is no step at the upper and lower ends of the display surface as shown by the phosphor lines 58 in FIG. Note that, similarly to FIG. 3, FIG. 4 also shows a portion of the mask 62 removed to expose a portion of the picture tube display surface.

However, as mentioned above, the predetermined contour limit line 88
If all strips whose centers are located within 1/2WRD from
This length is considerably longer than that of the standard slit-like aperture 64. Therefore, when this mask is formed into a dome shape, the long slit-like openings 63,
The mechanical strength in the vicinity of 69 is extremely reduced, and large strains occur in the portions of these long slit-like openings.

Therefore, in the present invention, in order to prevent such distortion from occurring, the regular strip portions 68 in each row 66 are
In addition to the above-mentioned long slit-like openings 63 with a WRD or more,
Add a new band to the center of 69. Reference numeral 72 in FIG. 5 shows an example of a shadow mask according to the present invention provided with such an additional strip A.

As is clear from the structure of the shadow mask 72 according to the present invention shown in FIG.
1, 73, 65, 67, and 79 all end in contact with the predetermined contour limit line 88, so that a display surface with smooth upper and lower contours without steps can be obtained. Since a slit-like aperture that is extremely long compared to the standard slit-like aperture 64 is not formed, the mechanical strength of the upper and lower ends of the mask does not decrease. In the shadow mask 72 shown in FIG. 5, the end slit-like openings 67 are approximately
6 standard length slit holes with a length of 1WRD
Although it is longer by the length of one strip compared to 4, the mechanical strength of that part will not decrease that much if it is this long, so this slit-like opening There is no need to provide additional strips at 67.

As is clear from the above description, in the shadow mask of the present invention, from the predetermined contour limit line 88 to 1/2
Since the band located within WRD has been abolished, if the length of the end slit-like opening is longer than 1WRD,
An additional strip A is provided in the center of the slot-like aperture. Incidentally, if the center of the strip exists at a position 1 WRD from the predetermined contour limit line, the end slit-like opening (for example, 85 in FIG. 6, which will be explained later) that is in contact with the contour limit line 88 is substantially Since it is of standard length, there is no need to provide additional strips in this slot-like aperture. Furthermore, if the center of the strip exists at a position approximately 1.5 WRD from the predetermined contour limit line 88, the first strip should exist near 1/2 WRD from the predetermined contour limit line 88. (For example, the strip 68 adjacent to the slot-shaped apertures 61, 65 in FIG. 5, and the strip 89 in FIG. 6), again in this case there is no need to provide an additional strip.

Although the above discussion assumes that the strip repeat distance WRD is constant, the scope of this invention includes embodiments in which the strip repeat distance varies slightly across the mask for special purposes, and also includes embodiments in which the strip repeat distance WRD is varied slightly across the mask for special purposes. Although an arrangement with rows is cited, the invention can also be applied to one with horizontal rows of apertures.

The slit-like apertures in a shadow mask are usually larger on the display surface side of the mask than on the electron gun side. This aperture shape is created by coating both sides of a sheet of mask material with a photosensitive coating, and then exposing the coating from one side and the opposite side of the mask material through corresponding photomasters. It is obtained by developing and then etching the mask material to form apertures. 6 and 7 show the aperture patterns 80, 82 of photomasters 84, 86 used to expose both sides of the shadow mask. A pattern 80 in FIG. 6 shows the same shape as the aperture formed on the electron gun side of the shadow mask, and a pattern 82 in FIG. 7 shows the same shape as the aperture formed on the display surface side of the shadow mask. . The pattern components of the pattern 80 on the electron gun side end at the contour limit line 88, but the pattern 80 on the display surface side
Two pattern elements extend beyond the contour limit line 88. The pattern row of the photomaster 86 used to expose the display surface side of the shadow mask protrudes outside the aperture area because a depression is formed on the display surface side of the shadow mask to form the mask into a dome shape. This is to reduce the stress that sometimes occurs. By weakening the outer circumferential region just outside the row of apertures, the external force on the mask strip is slightly reduced, making the strip less likely to tear during molding.

In the photomasters of FIGS. 6 and 7, the dashed line 90 inside the contour limit line 88 is the contour limit line 8.
The line from 8 to 1/2 WRD is shown. As follows from the figure,
Since the center of the strip is not between the broken line 90 and the contour limit line 88, the end slit-like openings of each opening row of the shadow mask made using this photomaster are as shown in FIG. It terminates at a contour limit line 88.

In addition, in FIGS. 6 and 7, A indicates a band-shaped portion added just inside the line 90 of 1/2WRD from the contour limit line 88 (closer to the center of the master) to form the shadow mask of the present invention. shows.
As explained with reference to FIG. 5, in the photomaster, the band portion within 1/2 WRD from the contour limit line 88 has been abolished, so that the end slit-like opening in contact with the contour limit line 88 is longer than 1WRD and less than 1.5WRD. When the length increases, an additional band-shaped portion A is provided approximately at the center thereof. The vertical dimension of this additional strip A is approximately half the vertical dimension of the regular strip. 6th
In the figure and FIG. 7, from the contour limit line 88
The line indicating the position of 1WRD and 1.5WRD is dashed line 92
and 94.

The criteria for strip removal used for the inside of the contour limit line 88 is used as is for the portion of the pattern of the photo master 86 shown in FIG. 7 that protrudes outside the contour limit line 88, except for the following corners. do. Removal of the band in the protruded section is necessary to prevent the band from forming partially at the contour line 88, which affects the shape or length of the aperture in that section.

Removing the strips from the outside of the contour line 88 creates the basic problem of reduced strength at the corners of the photomaster. In order to prevent this, a band-shaped portion is added at the position of the contour limit line 88 of the aperture pattern in the protruding portion at the corner of the mask. This additional band is shown as B in FIG.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional plan view of a porous shadow mask type cathode ray tube, FIG. 2 is a rear view of the shadow mask and face plate taken along line 2-2 in FIG.
Fig. 3 is a partially enlarged view showing the structure in circle 4 in Fig. 2 for a conventional picture tube, and Fig. 4 is a partially enlarged view showing the structure in circle 4 in Fig. 2 for a conventional improved picture tube. 5 is a partially enlarged view showing the structure in circle 4 in FIG. 2 of an embodiment of the picture tube of the present invention, and FIG. 6 is a partial enlarged view of the electron gun side of the shadow mask constructed according to the present invention. FIG. 7 is a partially enlarged view of a photomaster used to expose the display surface side of a shadow mask constructed according to the present invention. 20... Cathode ray tube, 32, 70... Display surface, 3
4,72...Shadow mask, 61,64,6
5, 67, 73, 79...slit-like opening, 66...
Slit-like aperture row, 68... band-like part, A... additional band-like part, 88... contour limit line.

Claims (1)

[Scope of Claims] 1. A cathode ray-excited linear fluorescent display screen, and a shadow mask installed in a tube at a distance from the display screen, and the shadow mask includes a plurality of substantially parallel rows. Slot-like apertures are formed, the slot-like apertures in each row being separated from each other by strips, and the strips of adjacent rows being longitudinally offset from each other, as described above. If we define the distance between the centers of adjacent strips in each row in the shadow mask as the strip repeating distance, then the distance from the contour limit line formed by the ends of each row to within about 0.5 times the strip repeating distance. All of the existing strips will be abolished, and due to the abolition of the strips, the end slit-like openings in contact with the contour limit line will be longer than the strip repeating distance and less than 1.5 times the strip repeating distance. In this case, the cathode ray tube is provided with an additional strip approximately in the center of the elongated end slot-like aperture.