JP2532226Y2 - Magnetic shield box for color TV - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a magnetic shield material for preventing discoloration and shaking of an image such as a color television and a color monitor.

(Prior Art) In a color television and a color monitor having a cathode ray tube, an electron beam from an electron gun hits R, G, and B phosphors to constitute each color.

Recent color televisions and color monitors are becoming larger and thinner, so that the electron beam flight angle of the cathode ray tube has shifted from 90 ° to 110 °. An image formed by such a configuration is very sensitive to an external magnetic field, and deviates from the trajectory of a flying electron beam by a slight magnetic field, so that a predetermined image is not formed. That is,
In a static magnetic field, a discoloration phenomenon occurs, and in an AC magnetic field, an image fluctuation phenomenon occurs.

Causes of the generation of the static magnetic field include railways using direct current, magnets (normal conducting and superconducting magnets) used for MRI, etc., speakers, magnets, and electric devices using direct current. In addition, as a source of the AC magnetic field which causes the problem of shaking, there are a transmission line, a transformer, and an electronic or electric device using the transformer.

As these sources increase and the cathode ray tubes become more sensitive, each manufacturer takes measures against magnetic shielding.
In other words, an internal shield that puts a soft magnetic material in the cathode ray tube and an external shield that places a soft magnetic material between the housing and the cathode ray tube have been studied and implemented. Not.

(Problems to be solved by the present invention) The discoloration and shaking phenomenon of the image differ depending on the direction of the magnetic field, and it is necessary to consider various countermeasures. The problem is solved by providing a double or triple shield with an external shield that inserts a television or monitor into the configured shield box. Soft magnetic materials include pure iron, silicon steel, permalloy, and amorphous metal. When constructing a shield box with these materials, it is necessary to take into account structural considerations such as welding and use of reinforcing materials. Due to the problem described above, the interior and exterior materials are used, so that the price is high and there is a problem that it is difficult to use. When judging from images such as medical equipment and control equipment, it is absolutely indispensable. In order to enjoy television which is indispensable in daily life, a low-cost shield method has been desired.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the problems of the prior art and to provide a low-cost shield material that can be easily constructed.

(Means for Solving the Problems and Their Functions) The present invention provides a soft magnetic material having an L-shaped structure to solve the problems described above.

As a magnetic shielding material, high magnetic permeability of pure iron, silicon steel, permalloy, magnetic amorphous alloy, etc. is used to bend the path by passing the magnetic field of one space through the material so that it does not reach the other space. A magnetic susceptibility soft magnetic material is used.

FIG. 1 shows an L-shape. The plate width C has a large effect on the magnetic shielding characteristics and is sufficient if the length is longer than the length of the cathode ray tube. . The dimensions of A and B differ depending on the size of various televisions and monitors, and thus cannot be determined unequivocally. However, if a gap or abutment is formed in a box, a leakage magnetic flux is generated from the gap or abutment. The dimension D shown in Fig. 2 must be 10mm
The dimensions should be assured above. Desirably, it is 50 mm or more.

As shown in FIG. 2, the shield box needs only to be fixed directly to the television or the monitor so that A and B always wrap the L-shaped magnetic body, so that the shield box can be easily constructed and reduced in weight. be able to.

(Example) 29 inch type (670 x 625 x 440mm) due to the influence of railway overhead lines
Color televisions were discolored by vertical magnetic fields. As for the degree of discoloration, 2/3 of the area discolored from both ends of the screen toward the center. (Red to green) The magnitude of the magnetic field was 0.7 G.

A silicon steel plate having a thickness of 0.35 mm was formed into an L-shape having a width of 300 mm (C), a length of A of 550 mm and a length of B of 200 mm, and was subjected to black baking to prepare four sheets. An L-shaped sheet was arranged at a position flush with or slightly in front of the front of the television. And, as shown in Fig. 2, the wrap width (D) is 80 mm.
It was set to 125 mm, and two sheets were fixed between the sheets with double-sided tape between the sheets to form a shield box. The discoloration of the TV screen could be completely eliminated.
In addition, it is possible to prevent dangers such as cutting the hand with a very good appearance by applying a molding to the front seat part with rubber.

Under the conditions described above, the wrap width (D) is changed from -20 mm (that is, the opposing edges of adjacent shield plates are separated by 20 mm) to +80 mm
FIG. 3 shows the change ratio of the shield when it was changed up to (the overlapping portion was 80 mm). As is clear from FIG. 3, the wrap width (D) is preferably 10 mm or more, and more preferably, 50 mm or more.

(Effect) The thickness of the magnetic shield material is about 0.1 mm to 1 mm, and although the wrap portion always has a step, the appearance is good because it is thin. The combination of the four shield plates can be applied to several types of color televisions without making a shield plate for each size of the color television. It is also advantageous.

Further, after the combination, the double-sided tape or the adhesive is sufficient for the wrap portion, and there is no problem in strength because it is in direct contact with the television or monitor.

[Brief description of the drawings]

FIG. 1 is a perspective view of an L-shaped magnetic material, and FIG. 2 is a front view showing a relationship between assembly of the L-shaped magnetic material and a television. FIG. 3 is a graph showing the wrap width and the shield change rate. In the figure: 1 ... L-shaped magnetic material, 2 ... TV, A ... Length,
B: length, C: width, D: wrap width.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Misao Kaneko 810 Kumagaya, Kumagaya-shi, Saitama Riken Kumagaya Office (72) Inventor Yukio Toda 810 Kumagaya, Kumagaya-shi, Saitama Riken Kumagaya Office (72) Inventor Yoshiyuki Masuko 810 Kumagaya, Kumagaya-shi, Saitama Prefecture RIKEN Co., Ltd. Kumagaya Works (56) References JP-A-61-95599 (JP, A) Japanese Utility Model 1983-58-23476 (JP, U) Japanese Utility-Model Utility Model 54-135624 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] The present invention has four shield plates made of a thin L-shaped soft magnetic material and having a depth dimension of 100 mm or more, and the corners of each shield plate are opposed to the outer corners of a color television or a color monitor. In addition, a shield plate is arranged in parallel with the outer wall of a color television or a color monitor, and one end of one shield plate is fixedly combined so as to overlap at least 10 mm with the end of another shield plate to form a shield plate housing. Shield box.