JPH02220334A - Color picture tube - Google Patents

Abstract

PURPOSE:To obtain a rigid internal magnetic shield primarily by bending by integrally forming small-opening edges of four trapezoidal areas that constitute a cylindrical section from the start. CONSTITUTION:An internal magnetic shield 8 is formed by bending after blanking of a single magnetic plate. A cylindrical section 9 which is actually a truncated pyramid in shape is made up of trapezoidal areas 10, 11 along a horizontal axis, trapezoidal areas 12, 13 along a vertical axis and corner areas. Long, narrow edges 10a-13a along the bases of the trapezoids are bent outward to form opening edges which serve as fixed areas of a mask frame. The small-opening edge sides of the trapezoidal areas 10-13 are formed integrally from the start with bridges 14a, 14b provided at two edges of the opening. Adjacent joint margines 10b, 10c...13b, 13c at th side edges of the trapezoidal areas are joined together by spot welding P in an area A where they are partially overlapped. In this manner, an internal magnetic shield with a high mechanical strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color picture tube provided with a truncated pyramidal internal magnetic shield.

Prior Art Color picture tubes with less internal magnetic shielding usually have a third
It is configured as shown in the figure, 1 is the face panel,
2 is a phosphor film, 3 is a shadow mask, 4 is a mask frame, 5 is an internal magnetic shield, 6 is an electron gun, and 7 is a deflection yoke.

When an external magnetic field such as earth's magnetism acts on the electron beam emitted from the electron gun 6 and deflected by the magnetic field of the deflection yoke 7, mislanding occurs and the color purity characteristics deteriorate. The internal magnetic seal 'F', 5 attached to the mask frame 4 is for shielding the external magnetic field, and has a truncated pyramid-shaped cylindrical portion that constricts on the electron gun 6 side.

Problems to be Solved by the Invention However, when attempting to form such an internal magnetic shield by deep drawing, in addition to annealing for drawing, annealing is required to remove processing distortion, and the magnetic plate used as the material becomes soft and easily deforms. Furthermore, as disclosed in Japanese Utility Model Application Publication No. 55-111159, an internal magnetic shield is also obtained by joining two or more bent parts by welding, caulking, or the like. In this case, deep drawing and annealing are not required, but not only does it increase the number of processing steps and costs, but the mechanical strength is likely to be insufficient, especially at the joint, and the joint area at the joint must be widened. If you do so, the chain will be more likely to get scratches or become dusty due to vibrations, etc.

Therefore, the object of the present invention is to provide a robust, low-cost internal magnet that does not require deep drawing, annealing, or the joining of multiple parts, and can maintain the overall shape stably even though the process is mainly bending. The purpose is to provide a shield.

Means for Solving the Problems According to the present invention, the internal magnetic shield fixed to the mask frame at the edge of the large-diameter opening is formed from a single blanked magnetic plate. The truncated pyramidal tubular portion has a pair of trapezoidal regions facing each other across the horizontal axis and a pair of trapezoidal regions facing each other across the vertical axis,
The trapezoidal regions are connected to each other at the edge of the small-diameter opening on the electron gun side, and the adjacent trapezoidal regions overlap outside of the connecting margins provided on both side edges and are coupled by welding or the like.

Function With such a structure, the four trapezoidal regions forming the cylindrical part are integrally connected from the beginning at the free end edge of the small diameter opening, and (in addition, the mechanical strength and The dimensional accuracy is high in both cases.Furthermore, the four trapezoidal areas are overlapped and connected outside the joining margins on both sides of each side, but the overlapping area and joining points are small. Since it is located in the corner area, which is most susceptible to vibration and impact, there is little risk of deformation or scratches.

Example Next, the present invention will be explained with reference to embodiments shown in the drawings.

As shown in FIG. 1 and its expanded view in FIG. 2, the internal magnetic shield 8 is made of a single blank magnetic plate.
Manufactured through processing that mainly involves bending. The truncated pyramid-shaped cylindrical portion 9 consists of a pair of trapezoidal regions 10, 11 facing each other across the horizontal axis, a pair of trapezoidal regions 12°13 facing each other across the vertical axis, and a corner region, Elongated edge portions 10a, 11a along the bottom of each trapezoidal area,
12a.

13a is bent outward to form a large-diameter opening edge, and this large-diameter opening edge becomes a fixing area for the mask frame. In addition, the dashed-dotted line shown in FIG. 2 shows a bending line.

The four trapezoidal regions 10, 11, 12.13 are integrally connected from the beginning on the small diameter opening edge side located on the electron gun side, and the pair of bridge parts 14a, 14b for this purpose are on both sides of the small diameter opening edge. It is set in. On both side edges of each trapezoidal area, there are 10b, 10c, and 1l outside the joint allowance.
b, 11c, 12b.

12c, 13b, and 13c are provided, and adjacent ones partially overlap each other outside the joint margin, and are connected at the overlapping part A by spot welding P, riveting, caulking, etc.

Effects of the Invention As described above, according to the present invention, a robust internal magnetic shield can be obtained through processing mainly consisting of bending.
The mechanical strength and dimensional accuracy of the small-diameter opening edge, which becomes a free edge, can be improved. In addition, although the four trapezoidal areas are overlapped outside the joints provided on both sides of each side and joined by welding, etc., it does not require much overlapping area or joining points, and is the most resistant to vibration and shock. Since the joint is in the corner area, the overall mechanical strength is high.
It is possible to obtain effects such as no risk of generating scratches or foreign objects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the internal magnetic shield of a color picture tube embodying the present invention, and FIG. 2 is a developed view of the internal magnetic shield.
FIG. 3 is a side sectional view of the color picture tube. 9... Cylindrical part, 10, 11.12.13...
...Trapezoidal area, A, 10b, 10c, llb, llc
, 12b. 12c, 13b, 13c -・-・-Connection allowance outside, 14a. 14b...Bridge part.

Claims (1)

[Claims] The internal magnetic shield fixed to the mask frame at the edge of the large-diameter opening has a truncated pyramid-shaped cylindrical part formed from a single magnetic plate, and the part is located opposite to each other across the horizontal axis. It has a pair of trapezoidal regions that face each other and a pair of trapezoidal regions that face each other across the vertical axis, and each trapezoidal region is connected to each other at the edge of the small diameter opening on the electron gun side, and is connected to the adjacent trapezoidal region. A color picture tube characterized in that the color picture tubes overlap at joint portions provided on both side edges and are joined by welding or the like.