JPH0574364A - Color cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent the generation of a local distortion by farming a recessed bead on the whole circumference of a shadow mask original plate and a recessed bead laid along thereto on the outside excluding the corner parts thereof, and then forming curved surface by bratticing and a skirt part around a main surface by drawing, respectively. CONSTITUTION:The main surface of the original plate of a shadow mask 7 is formed of a porous area 71 and a non-porous area 72 on the outside thereof, and a recessed bead 73 is formed on the whole circumference of the area 72. Recessed beads 74, 75 laid along thereto are formed on the long side and short side excluding the corner parts of the bead 73, and a curved surface and skirt part around the main surface are then formed by bratticing and drawing, respectively. Thus, the stress added to the material of the mask 7 is weakened on the whole and nearly uniformed in the areas 71, 72. The generation of a local distortion can be prevented even if the mask 7 is thereafter installed to the panel of a color cathode-ray tube and subjected to high temperature heating and annealing effect in the manufacturing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube, and in particular, internal stress generated during overhanging or drawing is strongly retained in the material of the shadow mask original plate in the effective area, particularly in the area near the non-perforated area. The present invention relates to a shadow mask suitable for a color cathode ray tube for high definition television such as HDTV, which suppresses a phenomenon that appears as distortion due to heating or the like.

[0002]

2. Description of the Related Art In general, a shadow mask for a color cathode ray tube is produced by pressing a flat shadow mask original plate having electron beam passage holes formed therein into a curved surface having a desired curvature by a press die, and thereafter, The periphery of the main surface in which the non-perforated area exists around the perforated area is bent at a substantially right angle to the main surface by drawing to form a skirt portion. Then, the shadow mask is fixed to the mask frame at the end of the skirt. The shadow mask is attached to the fluorescent surface formed by dots or stripes of fluorescent materials of different primary colors formed on the inner surface of the panel of the color cathode ray tube in close proximity to each other, and is dedicated to a specific primary color passing through a certain electron beam passage hole. Of the above-mentioned electron beam is caused to impinge on the dots or stripes of the specific primary color phosphor on the phosphor surface. Since the screen displayed on the panel has a rectangular shape, the main surface of the shadow mask and the perforated area also have a substantially rectangular shape. The curved shape of the inner surface of the panel and the curved shape of the main surface of the shadow mask do not necessarily match, and the inclination angle of the electron beam passage hole when the electron beam passes through the electron beam passage hole is The electron flight distance from the electron beam passing through the electron beam passage hole to the fluorescent surface after the electron beam passes through the electron beam passage hole is different because it differs depending on whether the shadow mask is in the vicinity of the central portion or in the peripheral portion away from the center. It depends on the position on the surface. On the other hand, the dots and stripes of the primary color phosphors that form the fluorescent surface are arranged substantially uniformly on each part of the rectangular fluorescent surface in order to obtain good image quality. Therefore, the perforated area of the shadow mask original plate is actually not an exact rectangle, but rather is a dent near the center of the portion corresponding to each side of the rectangular screen, and it is slightly projected diagonally at the location corresponding to the corner of the screen. It has a shape. Therefore, the width of the non-perforated area on the main surface in the direction orthogonal to the side of the screen is wide at the center of each side and short outside the corner (diagonal extension direction) of the perforated area.

When a shadow mask original plate having electron beam passage openings (dot-shaped or stripe-shaped holes) as desired is subjected to overhanging for forming a curved surface and drawing for forming a skirt. , The force exerted by the material in the non-hole portion of the perforated region during machining is naturally stronger than the force exerted by the material in the non-perforated region, and the stress remaining inside the material after machining is also large in the perforated region. , Becomes smaller in the non-hole area. Although a measure is taken so that force is not applied to the effective area when forming the skirt portion, it is impossible to prevent the difference in residual stress from occurring. The shadow mask of the color cathode ray tube is used in the manufacturing process of the color cathode ray tube, for example, in the process of fusing the panel with the shadow mask attached to the funnel after forming the fluorescent surface and the exhaust process in the tube. After being operated, it is heated to a considerably high temperature by electron beam bombardment, either locally or locally. Since such heating and subsequent cooling process are performed slowly in time and are a kind of annealing work, the shadow mask is deformed or distorted as the internal residual stress is released. In addition, since the internal residual stress varies depending on the position on the shadow mask, each part will have uneven strain, and will have a shape different from the initially desired curved surface shape of the shadow mask formed by the overhang process. ..

Various countermeasures have been conventionally proposed in order to deal with the above problems, for example, Japanese Patent Publication No. 57-206.
No. 61 and Japanese Patent Publication No. 60-42580, at least one concave bead is provided in a non-perforated region around a perforated region, and in Japanese Utility Model Laid-Open No. 62-131352, there is a perforated region. An annular groove (concave bead) is provided over the entire circumference of
It is described that the depth of the groove is extremely shallow at the four corners and deep at the center of the four sides.

[0005]

However, according to the experiments by the present inventors, forming one concave bead over the entire circumference of the perforated region is not sufficient to sufficiently suppress the occurrence of strain. is there. Further, in the color cathode ray tube for HDTV, the distance between pixels forming a color display screen is small, and therefore the distance between the shadow mask and the fluorescent surface must be shorter than that in the conventional normal color cathode ray tube. Therefore, the width of the non-perforated area around the main surface of the shadow mask is narrowed, and particularly at the location corresponding to the four corners of the screen of the shadow mask in which the perforated area is projected in the diagonal direction,
The width of the non-perforated area is narrow even in the case of a normal large color cathode ray tube. Therefore, it is difficult to form a plurality of concave beads around the entire perforated region in the non-perforated region. Japanese Unexamined Patent Publication No. 3-88240 discloses that a plurality of concave beads are provided in the non-perforated region around the perforated region.
Although the accompanying drawings show a double concave bead provided at a position corresponding to a corner of the screen, it is not easy to actually form such a bead.

Further, in recent years, the demand for large-sized color cathode ray tubes has increased in proportion, but in the case of large-sized screens, the shadow mask is heated, the temperature rises, and the thermal expansion occurs due to the electron beam impact during use. The problem becomes more serious than it is for smaller screens. For this reason, amber, which is an alloy of iron and nickel and has a small coefficient of thermal expansion, has come to be used as a shadow mask material. However, amber is still softer than mild steel used in conventional shadow masks. Therefore, in the shadow mask using Amber,
Due to the overhanging process, the distance between the electron beam passage openings in the perforated area becomes easier to extend than in the case of mild steel, and the rigidity as a shadow mask for large screens such as amber is used. (Self-shape retention) becomes notable and handling becomes difficult.

The present invention solves the above-mentioned conventional problems and improves the HDT.
An object of the present invention is to provide a color cathode ray tube equipped with a practical shadow mask that can be used for high definition television such as V.

[0008]

In order to achieve the above object, in the present invention, a non-perforated region exists around a perforated region, is formed into a curved surface having a predetermined curvature, and has a substantially rectangular planar shape. In a color cathode ray tube provided with a shadow mask having a main surface to be formed and a skirt portion that is bent at a substantially right angle to the center of curvature in the periphery of the main surface, a flat shadow mask original plate with electron beam passage holes formed, first, In the non-perforated area around the perforated area, a concave bead that surrounds the entire circumference, and except for the vicinity of the diagonal extension of the perforated area, along each side of the perforated area that develops into a substantially rectangular shape, respectively, After forming the attached concave beads that extend near both ends of each side on the outside of the concave bead that surrounds the entire circumference, form a curved surface by overhanging, and then form the skirt part around the main surface by drawing. It was.

[0009]

If there is a concave bead in the non-perforated area, the inclination of the side wall of the groove-shaped cross section can be changed so that the non-perforated area can be easily deformed by a relatively weak force. When forming a curved surface by overhanging, if the concave bead is first provided in the non-perforated region, the difference in internal stress acting on the material between the perforated region and the non-perforated region will be reduced, Residual stress becomes weak. According to the present invention, if the concave bead that acts as described above is doubled in the non-perforated region around the perforated region except for the four corner portions, it is generated inside the shadow mask material during the overhanging process. The stress is reduced on the whole surface, and the difference in stress between the perforated region and the non-perforated region is much smaller than that in the case where no concave bead is provided or the case where the concave bead is provided is uniformized. The local distortion due to the internal residual stress is less likely to occur even by heating in the manufacturing process of the color cathode ray tube after mounting the shadow mask inside the panel or heating by electron beam impact in the operating state of the color cathode ray tube. Further, since the concave bead acts like a beam against a bending moment, it is apparent that the shadow mask according to the present invention is less likely to bend than the conventional shadow mask and is easy to handle.

[0010]

EXAMPLES The color cathode ray tube of the present invention will be specifically described below with reference to examples.

FIG. 2 is a side sectional view of the color cathode ray tube.
In the figure, 1 is a panel, 2 is a funnel, 3 is a neck tube, 4
Is a fluorescent surface, 5 are three dedicated electron beams for emitting red, green, and blue phosphors respectively, 6 is an electron gun, 7 is a shadow mask, 8 is a mask frame, and 9 is fixed to the mask frame. A leaf spring 10 is embedded in the inner surface of the panel skirt, and its end portion engages with a hole in the end portion of the leaf spring so that a shadow mask is closely faced to a fluorescent surface formed on the back surface of the panel through a mask frame. , 11 is a stud pin for detachably holding it, 11 is an inner shield for shielding the environmental magnetic field formed by a thin ferromagnetic plate, and 12 is a horizontal scanning from left to right on the fluorescent surface by deflecting the electron beam. Is a deflection yoke that displays an image by sequentially performing vertical scanning from top to bottom while repeating. Since the shadow mask itself is poor in self-shape-retaining property, it is first mounted on a mask frame formed in a frame shape with a relatively strong material having an L-shaped cross section, assembled into a shadow mask structure, and then mounted on the inner surface of the panel. When forming a fluorescent surface consisting of black matrix film and dots or stripes of three primary color fluorescent materials by photolithography technology, different photosensitive films are exposed and developed, but a specific shadow mask structure is combined with a specific panel. After the photosensitive film is exposed, it is necessary to remove the shadow mask when performing the work of developing and removing the unnecessary portion. Therefore, the combination of the leaf spring and the stud pin is made detachable as described above.

FIG. 1 (a) is a front view showing a quarter portion of a main surface of a shadow mask provided in a color cathode ray tube according to the present invention, which is divided by vertical and horizontal centerlines.
1B is a cross-sectional view taken along the line AA ′ shown in FIG.
FIG. 1C is a sectional view taken along line BB ′ shown in FIG.
The main surface of the shadow mask 7 is composed of a perforated region 71 and a non-perforated region 72 around the perforated region 71. Further, in the non-perforated region 72, a concave bead 73 formed over the entire circumference of the perforated region 71 and a length of the perforated region 71. A concave bead 74 formed along the side and a concave bead 75 formed along the short side of the perforated region 71 are provided. As shown in this figure, since the width of the non-perforated region 72 is narrow at the diagonal extension of the perforated region 71, that is, at the corner, only the concave bead 73 is provided as shown in FIG. 1C. Since the width of the non-perforated region 72 is sufficient in the portion along the long side or the short side of the perforated region 71, as shown in FIG.
As shown in (b), in addition to the concave bead 73 formed over the entire circumference, concave beads 74 and 75 extending along the side to near both ends of the side are provided. Since this is done, the stress applied to the material of the shadow mask during the overhanging process is weakened over the whole area, and is made almost uniform in the perforated region and the non-perforated region, as shown in FIG. After mounting the shadow mask 7 on the mask frame 8 to assemble it into a shadow mask structure and mounting it on the panel of the color cathode ray tube, the shadow mask 7 is heated to a high temperature during the manufacturing process of the color cathode ray tube or in the actual operating state, and its burning is performed. When the internal effect remaining in the shadow mask material is released and relaxed by the grading effect, no local strain appears.

FIG. 3 shows another embodiment of the present invention.
In the case where the width of the non-perforated region 72 along the short side of the shadow mask main surface is small and a concave bead 73 cannot be additionally provided in addition to the concave bead 73,
It is a front view of the part of 4. When the non-perforated region 72 has such a narrow width that the second concave bead cannot be attached along the short side, the depth of the concave bead 73 is made as deep as possible at this portion according to the gist of the present invention. .. If necessary to make it deeper, make it a little wider. In this way, the effect is slightly inferior to the case where two concave beads are provided, but even if only one concave bead 73 is provided on the short side, a considerable effect can be obtained.

FIG. 4 shows still another embodiment of the present invention. When the second concave bead 74 is attached, the second concave bead 74 is attached to the concave bead 73 provided over the entire circumference. Up to, the width of the non-perforated area 72 is narrow near the corner of the main surface, and the length of the attached concave bead 74 becomes too short. It is a front view of the 1/4 part divided. In this example, the attached concave bead 74 is provided near the corner of the main surface so that the concave bead 73 is gradually provided over the entire circumference.
At the corner of the main surface where the non-hole portion has a narrow width, the two concave beads are merged into one. With this, the length of the attached concave bead can be increased, and the effect thereof can be increased.

[0015]

As described above, according to the present invention, the internal stress remaining in the material of the shadow mask is entirely weakened after the overhanging process for forming the flat shadow mask original plate on the curved surface, and It is possible to make the holed area and the non-holed area uniform so that there is almost no difference, and after the shadow mask is mounted on the panel of the color cathode ray tube, the shadow mask is heated and cooled by cooling (mainly by heat radiation). Even after passing through a similar process, local distortion does not appear, and the initial desired shape and size can be almost maintained, and the color cathode ray tube of the present invention using such a shadow mask causes color misregistration. It is almost completely suppressed. Further, in the shadow mask as described above, since the concave bead acts as a reinforcing beam to increase the rigidity, the shadow cathode mask of the present invention is easy to handle even if it is large, and the productivity is good.

[Brief description of drawings]

FIG. 1 (a) is a front view showing a quarter portion of a main surface of a shadow mask provided in a color cathode ray tube according to the present invention, which is divided by vertical and horizontal centerlines.
1B is a cross-sectional view taken along the line AA ′ shown in FIG.
FIG. 1C is a sectional view taken along line BB ′ shown in FIG.

FIG. 2 is a side sectional view of a color cathode ray tube according to the present invention.

FIG. 3 is a diagram showing an example in which measures are taken in accordance with the gist of the present invention when the width of the non-perforated region is narrow and it is difficult to provide two concave beads.

FIG. 4 is a view showing an example in which the length along the side of the attached concave bead is made as long as possible when the width of the non-hole region is narrow.

[Explanation of symbols]

1 ... Panel, 2 ... Funnel, 3 ... Neck tube, 4
... Fluorescent surface, 5 ... Three dedicated electron beams for emitting red, green, and blue phosphors, 6 ... Electron gun, 7 ... Shadow mask, 8 ... Mask frame, 9 ... Fixed to the mask frame Leaf spring, 10 ... stud pin implanted on the inner surface of the panel skirt, 11 ... inner shield, 1
2 ... Deflection yoke, 71 ... Perforated region, 72 ... Non-perforated region, 73 ... Recessed bead formed over the entire circumference,
74 ... A concave bead formed along the long side, 75 ... A concave bead formed along the short side.

Claims (1)

[Claims] 1. A main surface having a non-perforated area around a perforated area, formed into a curved surface having a predetermined curvature, and having a substantially rectangular planar shape, and a substantially right angle around the main surface toward the center of curvature. In a color cathode ray tube provided with a shadow mask having a bent skirt portion, a flat shadow mask original plate having electron beam passage holes formed therein is first formed in a non-perforated area around a perforated area and a concave shape surrounding the entire circumference. Except near the bead and the diagonal extension of the perforated region, along each side of the perforated region that develops in a substantially rectangular shape, extend to the outside of the concave bead that encloses the entire circumference and near each side end. A color cathode ray tube, comprising: a shadow mask formed by forming an attached concave bead, forming a curved surface by overhanging, and then forming a skirt portion around the main surface by drawing.