JPH0736317B2 - Color picture tube manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a shadow mask type color picture tube.

(Prior Art) In general, a shadow mask type color picture tube has a vacuum envelope composed of a panel, a funnel and a neck, and has a phosphor screen composed of RGB phosphor stripes on the inner surface of the panel. An in-line type electron gun that emits an electron beam that causes a phosphor to emit light is installed on the neck. Furthermore, a shadow mask having a large number of slot-shaped through holes is provided near the phosphor screen, and the distance between the inner surface of the panel and the shadow mask (usually called the q value) is always kept constant. It is structured to be.

However, the shadow mask surface may vibrate as shown in FIG. 5 due to external vibration or a loud sound from the speaker when the color picture tube incorporated in the TV set is operated. In this way, when the shadow mask (17) vibrates due to external vibration, the above q value changes, causing a color shift phenomenon in which the electron beam does not impinge on the regular phosphor, and the image on the phosphor screen There is a problem of degrading quality. In particular, in recent years, the panel face surface has become flatter or larger, and the curvature radius and surface area of the shadow mask curved surface have also increased, and low thermal expansion materials have come to be used as the shadow mask material. And such problems have become more prominent. That is, due to the flatness or size of the shadow mask, the overhanging force of the curved surface of the shadow mask is weakened, and the shadow mask easily vibrates.
In addition, the low thermal expansion material has a high Young's modulus and is often made to have a curved surface with a larger radius of curvature than that required because it is difficult to plastically deform, or the stress that tries to return to its original shape after press molding is strong. The so-called spring back, which causes the shadow mask peripheral portion to be warped, causes local deformation, and vibration is concentrated on the locally deformed portion, and the color shift is likely to occur.

In order to solve such inconvenience, the applicant of the present invention previously filed Japanese Patent Application No. 60-1
According to No. 37956, in which the shadow mask is welded to the inside of the mask frame, after heating the mask frame, the shadow mask and the mask frame are combined and after the two have returned to room temperature, they are welded and fixed and then cooled. Inward stress is applied to the periphery of the shadow mask welded to its inner wall by the contracting force of the mask frame, and as a result, internal stress is exerted on the shadow mask to enhance the shape maintenance ability and suppress vibration. I suggested that.

(Problems to be Solved by the Invention) However, in such a conventional technique, since the shadow mask is attached inside the mask frame, it is difficult to assemble, and it takes a long time for the shadow mask and the frame to cool to room temperature. There is.

The present invention provides a method for efficiently producing a shadow mask that suppresses vibration of the shadow mask and has a small amount of color misregistration on the screen by a simple method.

[Structure of Invention]

(Means for Solving Problems) The present invention has been made in view of the above points, and a shadow mask whose inner diameter is sufficiently larger than the outer diameter of the mask frame is provided on the outer side of the mask frame with the peripheral edge portion of the shadow mask. A method of manufacturing a color picture tube that is welded and fixed at multiple locations.
The method comprises a step of welding and fixing the shadow mask to the outside of the mask frame in a state where the mask frame is heated and expanded, the shape of the shadow mask is always kept constant, and vibration of the shadow mask is suppressed.

(Function) A shadow mask having a diameter sufficiently larger than that of the mask frame is welded and fixed to the outside of the mask frame in a heat-expanded state at a plurality of places, so that the mask frame is welded and fixed to the frame of the shadow mask when it is in a room temperature state. The peripheral part is pulled inside the shadow mask as the mask frame contracts and receives a force in the direction of the shadow mask curved surface, which can increase the mask effective curved surface protruding force and suppress the shadow mask vibration. It

(Example) Hereinafter, one example of a method for manufacturing a color picture tube of the present invention will be described in detail with reference to the drawings. That is, as shown in FIG. 4, the color picture tube comprises a vacuum envelope composed of a substantially rectangular panel (1), a funnel-shaped funnel (2) and a neck (3). Then, a phosphor screen (4) consisting of striped phosphor layers emitting red, green and blue respectively is adhered and formed on the inner surface of the panel (1), and the neck (3) is horizontally mounted on the panel (1). A so-called in-line type electron gun (6) which is arranged in a line along the axis and emits three electron beams (5) corresponding to red, green and blue.
Is provided. A shadow mask (7) having a large number of slit-shaped through holes is welded and fixed to the outside of a frame-shaped mask frame (8) at a position close to and facing the phosphor screen (4). Further, the mask frame (8) is locked and supported by a panel pin (10) embedded in the inner wall of the upright portion of the panel (1) via a spring (9).

The three in-line array electron beams (5) are deflected by a deflecting device (not shown) outside the funnel (2), scan a rectangular area corresponding to the rectangular panel (1), and perform a shadow mask (7). ), The color is selected through the apertures and landed on the striped phosphor layer to reproduce a color image. In addition, the electron beam may not be accurately landed on the stripe-shaped phosphor layer due to the influence of an external magnetic field such as the earth's magnetism. In order to prevent the color purity of the reproduced image from deteriorating, a ferromagnetic metal is provided inside the funnel (2). A magnetic shield (11) made of a plate is locked via a frame (8).

As shown in FIG. 1, a shadow mask for a color picture tube generally uses a flat plate material made of a cold rolled steel plate formed into a curved shape by press molding. The shadow mask (7) is a curved main surface (7a) having many small holes.
And a skirt portion (7b) bent and extended from the periphery of the main surface (7a), the inner diameter of which is sufficiently larger than the outer diameter of the mask frame (8) before assembly.

Next, using FIG. 1 to FIG. 3, a shadow mask (7)
A method of manufacturing the mask frame (8) will be described. First, a flat plate mask having a large number of through holes is press-molded so that the main surface (7a) has a predetermined spherical shape. In this shadow mask (7), the inner diameter of the skirt portion (7b) is about the outer diameter of the mask frame (8) with respect to the mask frame (8).
It is 5 mm larger. Next, as shown in FIG. 2, the mask frame (8) is heated and expanded to the state of the solid line (8a). Thus, the thermal expansion causes the mask frame (8) to have a large diameter as shown in (8a), and the inner diameter of the shadow mask (7) and the outer diameter of the mask frame (8) are substantially the same. In this state, the shadow mask (7) and the expanded mask frame (8) are welded, but it is possible to weld them without uneven distortion. Further, when the mask frame (8) is expanded by heat, temperature and time are set so that the shadow mask (7) and the expanded mask frame as described above can be fitted accurately. In Figure 3,
After welding the shadow mask (7) and the expanded mask frame (8a), the mask frame is cooled and the welded portion of the shadow mask (7) and the mask frame (8) is returned to the shape before the heat treatment. A sectional view is shown. As is clear from this figure, the shadow mask (7) receives a force (F) for projecting the shadow mask curved surface as shown in FIG. 3 due to the mask frame (8) contracted by the cooling. Due to the overhanging force (F), looseness on the curved surface of the shadow mask (7) is eliminated and the force for holding the curved surface of the shadow mask against external vibration becomes stronger. Further, by making the outer diameter of the mask frame (8) smaller and increasing the overhanging force, it is possible to obtain the curvature amount of the shadow mask curved surface that could not be plastically deformed by press molding of the low thermal expansion material. As described above, when the temperature of the shadow mask returns to room temperature, the contraction force of the mask frame pulls the shadow mask skirt inward, leaving a predetermined overhanging stress on the curved surface of the shadow mask. The structure is assembled in the color picture tube envelope, and the color picture tube is manufactured by a usual method. The inner diameter of the shadow mask depends on the heating temperature of the mask frame, but if it is about 2 mm to 10 mm larger than the outer diameter of the mask frame, the effect of improving the overhanging strength due to shrinkage of the mask frame after heating and welding will be obtained.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain a shadow mask type color picture tube which easily and efficiently reduces the so-called color shift phenomenon in which the shadow mask vibrates due to external vibration and the electron gun beam does not reach a predetermined phosphor. You can

[Brief description of drawings]

1 to 3 are views for explaining an embodiment of the present invention. FIG. 1 shows a shadow mask and a mask frame before assembling, and FIG. 2 shows a state in which the mask frame is heated and combined with the shadow mask. FIG. 3 shows a state in which the shadow mask and the mask frame have been welded and fixed and then returned to room temperature, FIG. 4 is a sectional view for explaining the color picture tube, and FIG. 5 shows an example of a conventional shadow mask. (1) …… Panel, (2) …… Funnel, (3) ……
Neck, (7) …… Shadow mask, (7a) …… Shadow mask main surface, (7b) …… Shadow mask skirt, (8) …… Mask frame.

Claims (2)

[Claims] 1. A step of forming a flat plate mask having a large number of through holes into a predetermined shape having a skirt portion in the peripheral portion, and a frame body having an outer diameter sufficiently smaller than the inner diameter of the shadow mask. The mask frame is heated and expanded so as to have a size close to the inner diameter of the shadow mask, the step of combined welding and fixing so that the outside of the heated mask frame is located inside the skirt of the shadow mask, and room temperature It returns to the state and the process of incorporating the shadow mask structure in which the contraction force of the mask frame is exerted and the overhanging stress remains on the curved surface of the shadow mask into the vacuum envelope of the color picture tube, Production method. 2. The method of manufacturing a color picture tube according to claim 1, wherein the inner diameter of the skirt portion of the shadow mask is 2 mm to 10 mm larger than the outer diameter of the mask frame.