JPH0580096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a color picture tube, and particularly to a shadow mask thereof.

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION As shown in FIG. 1, a conventional color image receiving device transmits three electron beams 10 corresponding to red, green, and blue, respectively, through an effective part 3 having a large number of apertures 4 of a shadow mask 2. Panels 1 at predetermined intervals, concentrated through
Generally, a method is used in which the light is dispersed again while reaching the inner surface of the fluorescent surface (not shown) and is caused to properly strike the red, green, and blue color-emitting phosphors. The shadow mask 2 is bent at a bent portion 5 extending from the periphery of the curved effective portion 3 to form a side wall portion 6 in a direction substantially parallel to the tube axis, and is fitted and supported by a mask frame 7, and is further fixed to the mask frame 7. 7
is latched to a panel pin 9 provided on the side wall of the panel via a frame holder 8, so that the effective portion 3 and the inner surface of the panel 1 are held at a predetermined distance. By the way, a shadow mask with this shape is
After forming a flat mask by etching a specified aperture into a thin flat iron plate of approximately 0.1 mm to 0.3 mm and punching out the outer shape, the mask is press-molded using a mold. That is, as shown in FIG. 2, the flat mask 11 is attached to a drawing mold consisting of a die 12, a mask holder 13, a wrinkle holder 14, and a punch 15 having the same curved surface shape as the mask effective area, and deep drawing is performed in the direction of the arrow of the punch 15. molded.
In this case, the flat mask 11 sandwiched between the die 12 and the crease presser 14 is pressed against the punch 15 during molding.
between the die 12 and the wrinkle presser 14 D _H
between the die 12 and the wrinkle presser 14 while being subjected to friction.
Slide from D _H to D _V between punch 15 and die 12.

At this time, the thickness of the flat mask 11 may not be constant, or foreign matter may adhere to the flat mask 11 or the die 12, the wrinkle presser 14, and the punch 15.
Furthermore, if the die 12 and wrinkle presser 14 or punch 15 are not engaged in parallel, the die 12
Since the frictional resistance generated on the side wall of the shadow mask between the crease presser 14 or the die 12 and the punch 15 is not constant, plastically deformed parts and elastically deformed parts coexist, especially at the side wall ends of the shadow mask. However, the drawing state becomes non-uniform, and the center position of the formed mask 2 after molding shifts. Furthermore, if the side wall is narrowed unevenly, as shown in FIG.
A shadow mask with a curved shape and a warp d at the tip 16 is formed.

Therefore, if the formed shadow mask has such distortion, it goes without saying that the electron beam will not be able to properly land on the predetermined phosphor, resulting in a serious problem of deterioration of color purity. bring.

OBJECTS OF THE INVENTION It is an object of the present invention to suppress distortion, have a highly accurate molded mask, and prevent deterioration of color purity.

SUMMARY OF THE INVENTION The present invention provides that when drawing a flat mask using a mold, near the tip of the side wall of the shadow mask,
A shadow mask that is molded with high precision by providing a protrusion or thick part that has greater frictional resistance with the mold than other parts, and making the length of this part 5 to 20% of the side wall length. This suppresses deterioration of color purity.

Embodiments of the Invention Examples of the present invention will be described in detail below with reference to the drawings. It should be noted that the present invention is the same as the conventional technology except for the applied shadow mask, so detailed explanation will be omitted.

In order to form a shadow mask with high precision, the shape of the side wall portion of the shadow mask is mainly important. In other words, when forming from a flat mask or deep drawing, the effective part of the curved surface with many apertures is determined by the contact area with the punch and the mask holder around the punch, so the entire area of the effective part is held by the mold. Although it is not necessary to do so, it is necessary that the side wall portion of the shadow mask, especially the vicinity of its tip, be sufficiently held by the mold. Therefore, the side wall of the shadow mask plays a guiding role during deep drawing.
In particular, frictional resistance at the tips of the side walls becomes a problem. The present invention is implemented based on such viewpoints,
One embodiment is shown in FIGS. 4 and 5. The vicinity of the tip 17 of the side wall portion 6 of the shadow mask 2 is formed to have greater frictional resistance than the side wall portion 6 other than the vicinity of the tip of the side wall portion when deep drawing a flat shadow mask into a curved surface. That is, tip 1
Since the plate thickness T near 7 is larger than the plate thickness t of the side wall 6 other than the vicinity of the tip, the D _V between the die and punch in the molding die is equal to the plate thickness T near the tip of this side wall. It is determined accordingly. Therefore, the side wall outer surface 1
Since the frictional resistance at 8 is substantially very small and frictional fixation occurs near the tip of the sidewall, deep drawing of the curved effective portion 3 and sidewall 6 of the shadow mask can be uniformly performed. The part of the plate thickness T near the tip of the side wall 6 can be easily formed by etching or the like during the production of the flat mask in the case of FIG. 4, or by the initial molding after the production of the flat mask in the case of folding as shown in FIG. Now, regarding the portion of the plate thickness T near the tip of the side wall portion, the plate thickness T is first determined based on the relative relationship with the plate thickness t of the other portions of the side wall portion. In other words, if the plate thickness T near the tip is 0.1 mm or more larger than the plate thickness t of the side wall, the influence of foreign matter during forming can be almost prevented, and the area near the tip is sufficiently frictionally fixed to achieve high-precision deep drawing. It was confirmed that this is possible. Next, the length L of the portion having the plate thickness T is similarly determined in relation to the length l of the entire side wall portion. As a result of various tests, the present inventor found that when the length L of the portion of the plate thickness T is less than 5% of the length l of the entire side wall portion, frictional resistance is too concentrated in the portion of the plate thickness T due to the narrow width. This is not preferable because the shadow mask may locally exhibit abnormal elongation or sometimes break. In addition, when the length L is 20% or more of the overall length l, the width is wide and the frictional resistance between the plate thickness T and other parts becomes too close, and sufficient frictional fixation is not achieved in the plate thickness T. Therefore, sufficient effects cannot be obtained.

FIG. 6 shows another embodiment of the present invention, in which a bead is provided near the tip 7 of the side wall portion 6 of the shadow mask 2. In FIG. In this case as well, the same effect as in the previous embodiment is achieved, but if the thickness of the side wall portion 6 is very thin, there is a risk that the bead will be deformed by the pressing force of the mold. Preferably, it is a bead.

In the above embodiment, if the thickness of the shadow mask is thicker than 0.2 mm, for example, the boundary with the side wall 6, that is, the bent part 5 will not be sufficiently sheared during deep drawing, and the rounded shape will not be formed. The molding accuracy may be impaired. In this case, a presser foot 19 may be separately formed at a corresponding portion of the downwardly bent portion 5.

Effects of the Invention As described above, according to the present invention, a shadow mask with sufficiently high precision can be obtained by forming a predetermined mold from a flat mask, so that the electron beam landing margin due to deformation of the formed shadow mask, etc. It is possible to suppress the decrease in color purity and prevent deterioration of color purity.

[Brief explanation of drawings]

Fig. 1 is a partial schematic diagram showing the vicinity of the shadow mask of a color picture tube, Fig. 2 is a schematic diagram for explaining the formation of the shadow mask, Fig. 3 is a schematic diagram for explaining the deformed shadow mask, and Figs. FIG. 6 is a partial schematic diagram showing an embodiment of a shadow mask applied to the present invention. 1... Panel, 2... Shadow mask, 3...
Effective part, 4...Aperture, 5...Bending part,
6... Side wall portion, 17... Near the tip.

Claims (1)

[Scope of Claims] 1. A color image receptor formed by drawing from a flat state, which consists of an aperture with a large number of apertures and a side wall portion that is bent at a portion extending from the periphery of the aperture. In the shadow mask for pipes, there is a friction resistance near the tip of the side wall when forming the shadow mask by sliding the side wall between the die of the mold and the crease presser between the punch and the die. It has a protrusion or thick part that is larger than other parts and serves as the main sliding part, and the length L of this protrusion or thick part is 0.2l to 0.05 with respect to the length l of the side wall part. A shadow mask for a color picture tube, characterized by being within the range of l. 2. The shadow mask for a color picture tube according to claim 1, wherein the thick portion is a bent portion. 3. The shadow mask for a color picture tube according to claim 1, wherein the projection is a bead.