JPS61171036A - 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 The present invention relates to a color picture tube having a perforated shadow mask mounted in close proximity to the cathode ray excited light emitting display surface of the picture tube. This invention relates to improvements in shadow masks that reduce elongation of holes.

BACKGROUND OF THE INVENTION Most color picture tubes currently manufactured are of the linear display surface slit mask type. Kowara's picture tube has a face plate with a spherical cross section and a linear display surface made of cathode ray excited luminescent material, and a shadow mask with a slit-shaped aperture near the display surface and a spherical cross section. .

The slit-like apertures of such a picture tube are arranged in rows approximately parallel to the short axis of the tube, with adjacent apertures in each row separated from each other by bridges of the mask.

Another widely used color picture tube is the dot display screen/hole mask type. Early entertainment picture tubes were of this type, but today they are primarily used for data displays.

Recently, several video tube variations have been proposed, one of which is the concept of a new faceplate panel profile that gives the illusion of being flat. A modification of this picture tube is described in U.S. Patent Application Nos. 469.772 and 469,77.
No. 4 and Nos. 529 and 644. The cross-sectional shape of the face plate of this modified picture tube is curved along both the long and short axes of the face plate panel, but is not spherical. In some preferred embodiments, the outer perimeter of the picture tube display surface is flat, or at least visually appears to be approximately flat. In order to obtain such a planar or substantially planar perimeter boundary, it is necessary to form the faceplate panel such that the curvature along the long axis is greater at the panel sides than at the center of the panel. be. This shape of the faceplate panel creates problems with shadow mask construction.

The shadow mask is formed into the final shape after etching the holes, but during this molding, distortion of the holes occurs due to elongation of the bridge-like portions, particularly near the outer periphery of the holes. Furthermore, in a shadow mask with slit-like apertures, the bridge-like portion near the outer periphery of the aperture array may be torn due to this elongation. The problem of distortion of the opening and damage of the bridge-like part is discussed in U.S. Patent No. 3, 809.
, No. 945. This patent uses a transitional structure weakened by reduced thickness or spaced depressions between the aperture array and the periphery of the mask. This weakened transient structure absorbs at least a portion of the tensile forces, reducing aperture strain and mask failure.

Although this embodiment of a transitional structure is suitable for early, approximately spherical shadow masks, the recent picture tubes mentioned above, whose outer perimeter boundaries are approximately flat, have large curvatures at least near two sides of the mask. requires a shadow mask with
Due to this large curvature, even if a weakened transient structure is used, it is not always possible to sufficiently absorb the tensile force of the mask, and it is not possible to prevent damage to the bridge portion or poor opening distortion. Therefore,
Furthermore, a special construction is required to overcome the distortion and breakage problems associated with modern color picture tubes.

<Summary of the Invention> The improved color picture tube according to the present invention has a substantially rectangular shadow mask attached at a constant interval J to the surface of the cathode ray excitation light emitting element in the envelope of the picture tube. This shadow mask has a perforated central portion, a peripheral intermediate portion surrounding the central portion, and an outer peripheral edge portion (skirt portion) surrounding the peripheral intermediate portion. At least two opposite sides of the shadow mask have a plurality of parallel grooves on the bidirectional surfaces of the mask in the intermediate portion, the grooves on one major surface being arranged alternately with the grooves on the other major surface. .

The presence of the groove in the middle portion of the mask allows the groove region in the middle portion to expand during mask molding, thereby reducing distortion in the perforated portion of the mask.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a generally rectangular color picture tube 1 having a Gates envelope 11 consisting of a rectangular face plate panel 12 and a tubular neck portion 14 joined by a funnel portion 16.
Indicates 0. Panel 12 includes a viewing faceplate 18 and an outer peripheral edge or sidewall 20 sealed to seven-channel section 16 by a glass frit 17. A rectangular three-color cathode ray excitation light emitting display surface 22 is arranged on the inner surface of the face plate V-) 18.

This display surface is a linear display surface having striations of phosphor approximately parallel to the short axis Y--Y of the picture tube (perpendicular to the plane of FIG. 1). There is a display surface 22 inside the face plate spring A/12.
A multi-hole color selection electrode, ie, a shadow mask 24, is detachably attached at a predetermined interval.

As shown by the broken line in FIG. 1, an in-line electron gun 26 is built into the center of the neck portion 14, and generates three electron beams that are directed from the beginning to the mask 24 along a concentrated path on the same plane. It is designed to lead to the display surface 22.

The picture tube lO of FIG. 1 is designed to use an external magnetic deflection yoke, such as the yoke 30 of the figure, surrounding the neck 14 and funnel 16 near their junction, thereby The book beam 28 is scanned horizontally in the major axis (X-X) direction and vertically in the minor axis (Y-Y) direction by the action of vertical and horizontal magnetic fluxes to form a rectangular mask on the display surface 22.

face plate) 18 has a major axis X-x and a minor axis y.
−Y, and the curvature along the short axis is greater than the curvature along the long axis near the center of the faceplate. The curvature along the long axis varies from a relatively large radius of curvature near the center of the faceplate to a small radius of curvature near the sides of the faceplate. The shadow mask has a substantially greater curvature along its long axis near its sides than near its center, giving it a shape somewhat similar to a face plate.

The shadow mask 24, which is illustrated in FIG.
It has three portions of an outer circumferential edge 36 that surrounds. The perforated central portion 32 has slit-like apertures 38 arranged in rows 40 generally parallel to the minor axis Y-Y.

Each adjacent aperture 38 in row 40 is separated from one another by bridges 42 of the mask. Forming the mask from a flat shape to a preformed shape places tensile forces on this bridge which tends to break it; however, in the illustrated mask embodiment, special This can be largely prevented by providing grooves. As shown in FIGS. 2 to 4, both left and right sides of the peripheral intermediate portion 34 have a plurality of parallel grooves 44 on one of the two main surfaces of the mask, and a second plurality of parallel grooves 46 on the other side.
The grooves 44 and 46 on the amphiphilic surface are alternately staggered in the direction of the long axis X-x. The advantages of these grooves can be seen by comparing the cross-section of the unformed mask in FIG. 3 with the warp of the formed mask in FIG. That is, if there is a groove in the intermediate portion 34, that portion expands during mask molding, thereby reducing the elongation of the bridge portion 42 and the distortion of the opening 38. This expansion causes groove 44.
46 occurs to form a wavy cross-section of the mask having a thin non-uniform thickness, approximately sinusoidal as shown in FIG. This approximately sinusoidal thin material stretches more easily during molding than the thicker perforated part of the mask, thus preserving the shape of the perforated part.

In the improved shadow mask 24, the groove 44 in the peripheral intermediate portion 34
．． 46, it becomes possible to bend and straighten each part of the waveform curve during mask molding. This is substantially different from the conventional mask disclosed in US Pat. No. 3,809,945, which weakens the mask by thinning the outer periphery of the mask or selectively etching specific patterns. When forming a mask like J, it is necessary for the peripheral part to overcome the tensile force and not stretch, but to do this, the cross-sectional area of the metal in the peripheral part must be smaller than the minimum effective cross-sectional area of the mask. However, there is a limit to the reduction in cross-sectional area of conventional masks because of the need to maintain the integrity of their overall structure. Therefore, the structure of this invention, in which the cross section is replaced with a geometric waveform curve extending like an accordion, is less likely to damage the bridge part of the mask or significantly deform the aperture than the intermediate structure of the conventional mask. The cross-sectional shape of the shadow mask can be substantially stretched without assistance.

The increase in elongation due to the mask 24 was theoretically calculated using a 27-inch (2-inch diagonal) picture tube, and the thickness was 0.21.
When grooves with a depth of 0.1401 EI% and a center spacing of 0.508 cm were provided on both sides of a 6 rttx mask, the elongation of the waveform region in the middle of one of the grooves was 4.47+m. For comparison, when measuring lines were drawn on a flat, non-corrugated mask material and the stiffness was formed into a predetermined mask shape, the elongation from the center to the side along the long axis was 6.35.
It was wn. Thus, the corrugations of the improved mask can absorb 4.47/6.35 or about 70% of the mask elongation during molding.

Although the present invention has been described above with reference to a preferred embodiment having different radii of curvature along the major and minor axes, the present invention can also be applied to picture tubes having spherical or other surfaces.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view of a shadow mask type color picture tube including an embodiment of the present invention, FIG. 2 is a front view of the picture tube of FIG. 1 before molding of a new shadow mask, and FIG. FIG. 2 is a sectional view taken along line 3--3 of the side portion of the shadow mask before molding, and FIG. 4 is a sectional view of the side portion of the mask after molding. lO...Color picture tube, 11...Envelope, 22...
・Cathode excitation light emission display surface, 24...Shadow mask, 3
2... Perforated center part, 34... Peripheral middle part, 36...
・Outer peripheral edge, 44.46...groove O

Claims (1)

[Claims] (1) It has a substantially rectangular shadow mask attached at a distance from the cathode ray excitation light emission display surface in the envelope,
The shadow mask has a perforated center portion, a peripheral intermediate portion surrounding the perforated central portion, and an outer peripheral edge portion surrounding the intermediate portion, and at least two opposite sides of the shadow mask have the above-described It has a plurality of parallel grooves on both main surfaces in the middle part, and the grooves on one main face are arranged alternately with the grooves on the other main face, and because of these grooves, the middle part A color picture tube characterized in that the grooved region of the mask is expanded to reduce distortion in the perforated central portion of the mask.