KR900002901B1 - Color cathode ray tube - Google Patents

Abstract

The structure comprises a shadow mask which has a main surface having a number of apertures and a skirt portion bent away from the surface. A frame supporting the skirt of the shadow mask is formed of a metal having a greater coefficient of thermal expansion than that of the shadow mask. The shadow mask is welded to the frame at a number of points. The structure is such that the skirt is subject to an inward compressive stress from the frame. The shadow mask structure is preferably rectangular and the skirt is such as to produce an elastic deformation of 2mm at maximum. The shadow mask may be of iron-nickel alloy and the frame of iron.

Description

Color awards

1 is a perspective view cut out a part showing a schematic configuration of a color water pipe with a shadow mask.

2 is a block diagram of color-coded electrodes.

3 and 4 are model diagrams for explaining thermal expansion of color-coded electrodes.

5A and 5B are model plan views and cross-sectional views for explaining the thermal expansion action when the frame is combined with the shadow mask.

6A and 6B are model plan views and cross-sectional views for explaining the thermal expansion action when the shadow mask and the frame are combined in the embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: panel 2: funnel

3: electron gun 4: phosphor

5: color-selective electrode 6: thin hole

7: shadow mask effective portion 8: shadow mask external edge portion

9: shadow mask skirt

10: frame

TECHNICAL FIELD The present invention relates to a shadow mask type color receiving tube, in particular, to a color-coded electrode configuration. Usually, the shadow mask type color tube has a panel (1), a funnel (2), an electron gun (3), a phosphor (4) emitting light in three colors applied to the inner surface of the panel (1), and the foregoing. The three electron beams emitted from one electron gun 3 serve as color screening, and consist of color screening electrodes 5 mounted at desired intervals facing the inner surface of the panel 1 described above.

As shown in FIG. 2, the above-mentioned color discriminating electrode 5 is a shadow mask effective portion 7 serving as a main surface having a plurality of voids or circular thin holes 6 for passing electron beams. The shadow mask outer edge (8) located outside the shadow mask effective portion (7), the shadow mask skirt portion (9) bent at approximately right angles to the shadow mask outer edge (8) described above, a relatively rigid structure The frame 10 and the frame 10 for welding the shadow mask body by welding at several places to mount the frame 10 at desired intervals opposed to the inner surface of the panel 1 described above. It is composed of a holder 11 fixed to the.

In addition, inexpensive steel is generally used for the material of the shadow mask and the frame 10 described above. As is well known, in a color water pipe with a shadow mask, three electron beams emitted from the electron gun 3 are deflected and then randomly drilled on the shadow mask serving as color discrimination (6). Although the light is projected onto a desired phosphor 4, for example, a phosphor emitting red, green, and blue light, the thin hole 6 of the shadow mask described above occupies the above-mentioned mask effective portion 7. Since the ratio is 15 to 25%, most of the remaining electron beams are projected onto the shadow mask described above.

As a result, the shadow mask described above is heated. For example, in the 20-inch color water tube, the center portion of the shadow mask described above is heated to about 70 ° C. in the operating state of the anode voltage of 25 KV and the anode current of 1200 µA.

Since the shadow mask described above is heated, the above-mentioned shadow mask thermally expands during the operation of the above-described color receiving tube, and the relative positional relationship between the thin hole 6 of the shadow mask described above and the phosphor 4 described above changes, and the electron beam The landing position on the phosphor is changed, and in extreme cases, the color purity is greatly reduced on the screen.

Thermal expansion of the shadow mask described above is generally divided into two cases. In the first case, the shadow masks 7, 8, 9 and frame 10 are formed in the pipe axis direction Z as shown in FIG. It is thermal expansion in the direction perpendicular to).

In the second case, if a particularly bright portion on the screen is locally present during the color water pipe operation, the shadow mask valid portion 7 described above corresponding to the above-described local portion is shown in FIG. ) Only thermally expands in a so-called dome shape in a direction parallel to the tube axis direction Z. In the first case, as shown in Japanese Patent Application Publication No. 44-3547, thermal expansion, when the above-mentioned shadow mask is mounted facing the inner surface of the panel 1 described above, the above-described frame 10 and the above-mentioned By interposing the bimetal between the holders 11, the shadow mask described above rises due to the projection of the electron beam, thereby bringing the shadow mask closer in the direction of the panel 1 along the tube axis to compensate. (I) has been a valid proposal.

Since the thermal expansion in the second case is a local thermal expansion at the time of color water pipe operation, no effective compensation method such as the above-described bimetal is shown.

In order to suppress the above-described local thermal expansion, as described in Japanese Patent Application Laid-Open No. 42-25446, Japanese Patent Application Laid-Open No. 50-58977, and Japanese Patent Application Laid-open No. 50-68650, for example, invar (invar) ) Has been proposed a method of using an alloy in the shadow mask described above.

In general, low thermal expansion metals, such as in-bar alloys, are more expensive than steel materials, and when the low thermal expansion metals are used in the above-described frame, which is heavy and bulky, together with a shadow mask, it is directly connected to a significant cost increase. Therefore, it is preferable to use only the above-mentioned shadow mask, which is relatively lightweight, and a low thermal expansion metal, and to use an inexpensive iron material for the above-mentioned heavy frame.

When the color-coding electrode is formed using the low-heat-expanding metal using only the above-mentioned shadow mask, when the color-coating electrode described above is in a high temperature state (for example, about 400 ° C.) during the manufacturing of the color receiving tube, the above-described low-heat-expanding metal Since the thermal expansion of the shadow mask is different from that of the steel frame described above, the shadow mask described above is pulled in the direction perpendicular to the tube axis by the frame described above, so that the shadow mask described above is fired as shown in FIG. (塑性) deformation. That is, in FIG. 5A, when the color-screening electrode becomes a high temperature state, the steel frame 10 becomes large in the arrow direction according to thermal expansion. On the other hand, the shadow masks (7) (8) and (9) made of low thermal expansion materials welded to the outer surface of the above-described frame in various places are almost unchanged, so the shadow mask is framed in the direction of the arrow as described above. As a result of receiving a tensile force from the entire outer surface, the shadow mask is plastically deformed as shown by the dotted line in FIG. 5B, resulting in poor color purity.

The present invention has been proposed in view of the above drawbacks, and an object of the present invention is to provide a color-selective electrode which does not undergo plastic deformation even when a low thermal expansion material is used only for the shadow mask body.

The present invention suppresses local thermal expansion during the operation of a color water pipe while welding the shadow mask made of the low thermal expansion material described above to various places inside the frame made of the above steel material, and at the same time the high temperature state of the color water pipe manufacturing. It is to provide a color water pipe which does not cause the above-mentioned plastic deformation even when it is.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

6 shows the shadow mask and the frame of the color-selective electrode used in the present invention. In FIG. 6, the shadow masks 7, 8 and 9 are low thermal expansion metals, such as in-var alloys containing 36% nickel, for example, while the frame 10 generally has a higher coefficient of thermal expansion than in-bar. It is made of low-cost steel, and the shadow mask described above is held by welding at various places indicated by the x mark on the inside of the frame.

When the color-selecting electrode shown in FIG. 6 is brought to a high temperature state during the production of the color water pipe, the above-described general steel frame is thermally expanded.

The above-mentioned thermally expandable frame imparts tension to the shadow mask in the direction indicated by the arrows in the drawing through the welded joints of the shadow mask and the frame described above, so that the shadow mask is deformed as indicated by the dotted line in the sixth speed, but the shadow mask is Since the tensile force applied to the main body is limited to a narrow range near the welded position described above, the above-described deformation of the shadow mask is limited to the shadow mask skirt portion 9, and the tensile force is considerably weaker than in the case of FIG. When it returns to room temperature from high temperature state, it is possible to recover to almost original shape.

In the color receiving tube operation, the above-described frame is thermally expanded, but the shadow mask effective portion 7 is not deformed because it is very small compared to the thermal expansion during the production of the above-described color water tube.

In FIG. 6, when the distance d of the upper end of the shadow mask skirt portion 9 and the welded mask shadow portion 9 indicated by the X mark becomes small, the thermal expansion of the frame during the manufacture of the color receiving tube is reduced. The shadow mask tensile force is not absorbed only in the shadow mask skirt portion 9, so that the aforementioned tension is applied to the shadow mask outer edge portion 8 and the shadow mask effective portion 7, and the same shadow mask as shown in FIG. Plastic deformation occurs.

As a result of examining the distance d of the upper end of the shadow mask skirt portion 9 and the welded portion of the shadow mask skirt portion 9, it is necessary to roughly satisfy the following relationship.

d> 0.5 × S

In the above relation, "S" is the diagonal length of the panel effective screen showing the size of the color image tube, the unit is inches, and "d" is the distance described above, and the unit is mm. In addition, when converting the unit of "S" into metric method and expressing as mm, it is set to d> 0.02 * S.

As described above, according to the present invention, it is possible to configure the color selection electrode using only the low thermal expansion alloy, so that local thermal deformation of the shadow mask can be prevented during the operation of the color receiving tube without enormous cost increase. There is a number.

Claims (2)

A shadow mask consisting of a main surface having a plurality of perforated holes and a skirt portion folded around the main surface and a frame for supporting the shadow mask with the skirt portion, wherein the shadow mask has a coefficient of thermal expansion more than the frame described above. In a color water pipe using a color-selective electrode composed of a low invar alloy, the shadow mask skirt portion and the frame are welded to each other so that the distance between the welded point and the upper end of the shadow mask skirt portion ( and d) (unit mm) is d > 0.5 x S (S is an inch size representing the size of an inch size of a color water pipe). The color water pipe according to claim 1, wherein the shadow mask is an in-bar alloy and the frame is made of steel.

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