KR950012699B1 - Crt with s/m - Google Patents

Abstract

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Description

Color picture tube with improved shadow mask-frame assembly

1 is a side cross-sectional view of a color image tube embodying the present invention.

FIG. 2 is a plan view of the rear of the faced panel and mask-frame assembly taken along line 2-2 of FIG.

3 is a schematic representation of a quadrant of a prior art shadow mask-frame showing thermal expansion.

4 is a schematic diagram showing a quadrant of the shadow mask-frame of the first degree and color imager showing thermal expansion.

* Explanation of symbols for main parts of the drawings

8: rectangular color image tube 10: glass envelope

12: face plate panel 24: shadow mask

30 mask-frame assembly 32 frame

36, 38: section

The present invention relates to a color image tube having a shadow mask attached to a peripheral frame suspended against a cathodoluminescent, in particular a corner support and to reduce the electron beam misregister for the pixels of the screen. An improved frame that cooperates.

It is common to use either three springs or four springs to support the shadow mask in the rectangular faceplate panel of the color imager. In three spring support systems, one spring is generally located at the upper center of the mask, and the other two springs are located along the side of the image tube between the lateral center of the mask and the lower two corners of the mask. In four spring support systems, the springs are located in the upper and lower centers of the mask and the left and right centers of the mask. In three spring support systems and four spring support systems, as described above, it is possible to cause the shadow mask to be slightly twisted and moved relative to the faceplate during manufacturing and imaging tube runoff.

One way to minimize distortion and movement of the shadow mask is to use a spring support located at four corners of the frame. Embodiments for obtaining such corner supports are shown in United States Patent No. 4,723,088 to Sonc et al. On February 2, 1988 and United States Patent No. 4,728,835 to Sonc et al. On March 3, 1988.

An improved image tube with corner supports is described in US Pat. No. 5,021,707 to Bauder on June 4, 1991. Unlike conventional picture tubes in which the springs and support studs are aligned diagonally to the faceplate panel, the Bauder patent describes the alignment of the springs and studs off the diagonal so that the support shaft forms an angle of 33 degrees to 50 degrees relative to the main axis of the panel. It is describing. The purpose of offsetting the support axis from the diagonal is to improve the resistance of the support to impacts.

The problem arises in that the support axis is offset from the diagonal, which occurs when the mask-frame assembly and the support means are heated and the expansion of the assembly causes the support spring to be reinstalled on the stud. The problem is particularly dangerous when the temperature of the burner tube reaches nearly 450 ° C during burner operation. Since such reinstallation may cause an electron beam miss register, it is desirable to solve such a problem. The present invention provides a solution to this problem.

The improved color imager comprises a vacuum envelope with a rectangular faceplate panel. The panel includes a shadow mask assembly mounted thereon by means of support located at the four corners of the panel and the viewing screen on its inner surface. The shadow mask assembly comprises a perforated shadow mask and a peripheral frame to which the mask is attached. The frame is formed by four sections that are welded together at their ends. The two sections are made of a material that is longer than the other two sections and has a coefficient of thermal expansion different from that of the other two sections.

FIG. 1 shows a rectangular color image light 8 having a glass envelope 10 comprising a tubular neck 14 connected by a rectangular faceplate panel 12 and a rectangular funnel 16. Panel 12 includes a peripheral flange or sidewall sealed with viewing faceplate 18 and funnel 16. The faceplate panel 12 has two orthogonal axes, i.e., a major axis X parallel to a wider length (generally horizontal) and a minor axis Y parallel to a narrower length (generally vertical). The major axis and the minor axis are perpendicular to the cell axis Z of the center of the image tube passing through the center of the neck 14 and the center of the panel 12. In a preferred embodiment, panel 12 has a 16x9 aspect ratio. The mosaic three color fluorescent screen 22 is located on the inner surface of the face plate 18. The screen is preferably a line screen with fluorescent lines extending substantially parallel to the minor axis Y. Alternatively, the screen may be a dot screen. Multiple perforated color section electrodes or shadow masks 24 are removably mounted spaced apart from the screen 22 at predetermined intervals. The electron gun 26 is mounted centrally within the neck 14 to generate three electron beams 27B, 27G and 27R and direct the screen 22 through the mask 24 along the convergence path.

The image tube of FIG. 1 is designed for use as an external magnetic deflection yoke 28 located in the vicinity of the funnel to net junction. In operation, yoke 28 directs the three electron beams into a magnetic field that causes the beam to scan horizontally and vertically onto a rectangular raster on screen 22.

The shadow mask 24 is part of the mask-frame assembly and also includes a new peripheral frame 32. The mask-frame assembly 30 is disposed in the faceplate panel 12 shown in FIG. As shown in FIG. 2, the mask-frame assembly 30 is mounted to the panel 12 by four support means 34 arranged in four corners of the assembler. Each support means 34 comprises a stud fitted to the panel side wall 20 and a spring attached to the plate welded to the frame 32 to engage the stud.

The new mask-frame 32 is formed from four sections, two long sections 36 and two short sections 38. The frame 32 substantially comprises a bi-vertical flange in the configuration of an L-shaped cross section. The first flange 42 extends from the intersection of the flanges in the direction towards the screen 22. The second flange 44 extends inwardly from the intersection of the flanges in the direction toward the longitudinal axis Z of the center of the image tube 8.

The four corners of the frame 32 are cut off at an angle to the side of the frame.

The frame 32 is ameliorated by constructing a section 36 that is placed from a material having a different coefficient of thermal expansion than the two short sections 38. Preferably, the elongated section 36 is made of a material having a lower coefficient of thermal expansion than the two short sides 38. The purpose of constructing the frame 32 from different materials can be identified by comparing FIGS. 3 and 4. 3 shows the expansion characteristics of a conventional frame having all sections formed of the same material. The solid line 46 represents the frame perimeter before it is heated and the dashed line 48 represents the frame perimeter after it is heated, such as during operation or processing of the image tube. Line D represents the diagonal of the frame and line SA represents the axis of the mask support means, for example springs and studs. As can be seen, the support means the axis forms an angle of 45 degrees with respect to the main axis X of the frame, but causes the expansion of the frame to cause the corners of the frame to expand along the diagonal D. This difference moves the corner of the frame laterally with respect to the line SA. This relative lateral movement causes the springs installed in the studs to twist, reinstall on the studs and set up pressure on the support means. Re-installation often causes movement of the mask-frame assembly, movement of holes with respect to the screen pixels, and causes electron beam miss registers.

In an image tube constructed in accordance with the present invention, twisting and reinstalling of the spring on the studs and increase in pressure are prevented by appropriately selecting the material used to make the frame. Selecting a material for the frame sections 36, 38 will cause the frame corners to extend in the X and Y axis directions by substantially the same amount, and during its tube operating and during the tube operation at its final operating temperature. The corner of the frame 32 will immediately extend along the 45 degree line of the support means axis SA. This movement of the frame corner is shown in FIG. In FIG. 4, solid line 32 represents the circumference of the new frame when it cools, and dashed line 32 'represents the circumference of the new frame when it is at its final operating temperature.

As in the illustrated example, consider an image tube having a 16x9 aspect ratio and a 45 degree angle between the support axis SA and the main axis X. If each section 36 is an ARMCO 18SR stainless steel (made by the United States, Maryland, Baltimore, stainless steel, ARMCO), their coefficient of thermal expansion is 10.6 × 10 ⁻⁶ ΔL / L / ° C. If the next short section 38 is a NITRONIC 32 stainless steel (also made by ARMCO), then the coefficient of thermal expansion of the single side 38 is 18.5 × 10 ⁻⁶ ΔL / L / ° C. or approximately 16 of the long side of the thermal expansion coefficient. / 9 times. This will ensure that the corners of the mask cross the support axis and allow for expansion of the imager glass.

The 45 degree lines in FIGS. 2 and 4 merely illustrate one of the angles of many support axes and are offset from the diagonals that may be used. When other support axes are used, the selection of a suitable material that can be made for the frame sections 36 and 38 will cause the frame corners to cross these axes in which the mask assembly extends.

Although frame 32 is shown in planar form, the present invention can be applied to any frame geometry, such as a barrel or bow. In addition, although the present invention has been described with respect to an image tube having a 16x9 aspect ratio, the present invention can be applied to image tubes having other aspect ratios including 4x3.

Claims (3)

A color image tube comprising a vacuum envelope having a rectangular faceplate panel, the panel comprising a shadowing screen-frame assembly mounted by a viewing screen on an inner surface and supporting means located at four coders of the panel, wherein the shadow mask- The frame assembly includes a perforated shadow mask and a peripheral frame to which the mask is attached. In the color picture tube, in which the support means are attached to the corners of the frame, the frame 32 is formed by four sections 36 and 38 welded together at their ends, the two sections 36 being different. A color imaging tube, characterized in that it is made of a material that is longer than the two sections 38 and has a coefficient of thermal expansion different from that of the other two sections. The color image correlator according to claim 1, wherein the long section (36) of the frame (320) is made of a material having a coefficient of thermal expansion lower than that of the short section (38). A color image tube comprising a vacuum glass envelope having a rectangular faceplate panel having two long sides and two short sides, wherein the panel has a long axis parallel to the long side, a short axis parallel to the short side, and opposite the panel. Two diagonals extending between corners and a longitudinal axis of the central axis passing vertically through the intersections of the long axis and the short axis, the panel being mounted by a viewing screen on the inner surface and supporting means located at four corners of the panel; A shadow mask-frame assembly, the shadow mask-frame assembly comprising a shadowed mask with a hole and a peripheral frame to which the mask is attached, the frame comprising two opposing long sections substantially parallel to the long axis, the Acute angles for two opposing short and long and short sections nearly parallel to the minor axis In a color picture tube in which the support means are located at the corners of the frame, the long section 36 of the frame 32 comprises thermal expansion of the short section 38. A color image tube comprising a material having a coefficient of thermal expansion lower than the coefficient.