SU1391510A3 - Cathode-ray tube - Google Patents

Abstract

A cathode-ray tube of the vertical line screen, slit apertured mask type includes a mask wherein the horizontal center-to-center spacing between adjacent apertures in the mask, and the spacing between the mask and screen, vary proportionally from the center to the edge of the mask.

Description

FIELD OF THE INVENTION The invention relates to electronic engineering, in particular to electron beam tubes (ELL) with shadow beams.

The purpose of the invention is to improve the color reproduction of the image by reducing the mismatch of the spots of the electron beams with the latency elements caused by the dome-shaped curvature of the shadow mask.

Figure 1 shows a portion of a mask and a CRT screen, located approximately midway between the center and the edge of the screen; FIG. 2 is a schematic side view of a CRT illustrating geometric relationships in a tube; FIG. Fig. 3 shows a CRT with an elastic pull-out on the front glass with a shadow beacon reinforced in it, a view, and separate parts of this mask; in fig. 4 and 5 are two variants of CRT with a flat front glass, top view, partly with an axial slit.

. Figure 1 shows a cathodoluminescent screen 1 with phosphor elements 2 deposited on it, a shadow mask 3 in the unheated state, and the same mask 3 in the heated state with the formation of a dome, as well as the boundaries of a part of the electron beam A passing through the hole in the unheated mask 3 (dotted line) and the face of the 1 part of the beam 4 passing through the answer in the heated mask 3 (itrich dotted line) with

Figure 2 shows the well-known mask 3 and the mask 5 with a greater curvature, made according to the invention.

The distance between the mask and the screen q is related to the gap between the centers of the holes of the mask and the ratio La

q is -zG where L is the distance from the P-P deviation plane to screen 1; S is the distance from the electron-optical axis of tube A-A to the point of intersection of the center of the non-axial electron beam with the plane of deflection P – P. Fig. 3 shows an embodiment of a mask according to the invention with a radius of curvature of 850 mm, the value a and the width of the slits are given in millimeters. Here, the distance between the centers of the holes in the mask 5, which has a large curvature, varies from 0.77 in

f

o

5 0 5

0

five

0

five

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five

center 6 of the mask to 0.885 at the midpoint of 7 and up to 1,000 mm at the edge 8 of the mask. In order to save mask transmission, the slit width is increased compared to the width of the prototype slit. In the CRTs 9 and 10 shown in Figures 4 and 5, the screen I is flat and the mask 5 is spherical (Figure 4) or with a curvature that changes its sign from the center to the edge (Figure 3) to impart greater strength to the mask.

CRT works as follows.

When a CRT is turned on, electrons hitting the mask cause it to heat up. Since the mask is attached to a massive frame serving as a heat sink, a temperature difference forms between the middle and the edges, as a result of which the center of the mask, its edge and frame expand with different speeds, which causes some parts of the mask to be domed towards the screen. In the center of the mask, the dome formation is small, affecting the coincidence between the electron beams and the phosphor elements, since the direct projection of the beams remains unchanged with changing - the distance between the mask and the screen. The edges of the mask are not dome forming, as they are attached to the frame. The maximum discrepancy due to the dome formation is observed approximately midway between the center of MS. And its edge.

The mismatch is defined as the magnitude of the displacement of the electron beam relative to its phosphoric element, Tc;. The discrepancy effect from the dome reaches a maximum value after 3-5 minutes after the start of the tube operation, but continues to have a lesser effect on the tube operation for another 10 or 15 minutes. When the tube has reached stable temperature temperatures, the electron beam mismatch is compensated by temperature-sensitive frame fasteners moving the mask assembly to the screen. Since at the edge of the mask, i.e. the frame, from, the water heat is always greater, everything. there will be some deflection due to temperature transition processes. As the Ivy life of the shadow mask increases, the dome formation and warping decrease, as well as the offset and the displacement caused by them. By increasing the curvature, it is possible to increase the strength, and therefore reduce the distortion, and due to the geometric

When the mask is heated, the point on the mask, and the price curve has a greater curvature, moves toward the screen by a smaller amount. For example, the movement of the mask area towards the screen decreases from approximately 48 μm with a radius of curvature of the mask of 1000 mm to 30 μm with a radius of 850 mm.

The table shows the interstitial relations of the chalk, the mask and the screen for the known and the proposed tubes, as well as the tolerances and discrepancies from the poling for these tubes. The first column shows the distance q at the edge of the screen along the main axis, and in the second, diagonally to the distance q in the center of the mask. The third and fourth columns show tolerances and results of mismatch measurements as a result of dome formation for known and new tubes (mask curvature, respectively, 850 mm and 1000 mm) at points in the middle, between the centers and edges of the tubes.

The increase in tolerance in the new tube is due to the increase in distance a and the reduction in mismatch due to dome formation — an increase in the curvature of the shadow mask; 27 mm in the table).

The invention also makes use of flat front glass (Fig. A), with the curvature of the mask

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five

five

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It also has a reverse sign to impart greater strength to the mask (figure 5).

Claims (2)

1. Electron-beam tube, containing a shadow mask with holes for combining electron beams with phosphor elements of a cathodoluminescent screen, while the distance between the mask holes is variable, and the change in the gap between the shadow mask and the catholeshmic screen proportional to the change in the distance between adjacent apertures of the mask, characterized in that, in order to improve the color reproduction of the image by reducing the mismatch of the spot of the electron beams with the phosphor element At least part of the mask is made with a curvature defined by the ratio of the maximum gap between the shadow mask and the cathodoluminescent screen to the minimum gap for this part of not less than 1.30. 2. Tube POP.1, characterized in that the ratio of the maximum gap between the third mask and the cathodoluminescent screen to the minimum screen is the ratio of the gap at the edge to the gap in the center of the screen. Famous 48 cm - 63 cm - 10 ° C Suggested options I option 2, 63 cm 1,131.12 1,101,090,053 0.079 -0.026 1,471.45 1,581,480,067 0.066 0.001 . // 7 Fig.Z FIG. If  yy - - 2 4LJ