JPH03240389A - Magnetic shield box for crt - Google Patents

Abstract

PURPOSE:To offer a magnetic shield box itself in expensively to market by forming continuously a ceiling part, left/right side wall parts and a bottom plate part through the folding of a bent part orthogonal to a rolling direction of an oriented silicon steel strip. CONSTITUTION:An inexpensive oriented silicon steel strip is employed and it is folded at a bent part A orthogonal in the rolling direction to form continuously a ceiling plate 1, left/right side wall parts 3,4 and a bottom part 2 and a front side is used as an opening 9. Moreover, a butt part B of the start and end of the oriented silicon steel strip is placed in a same direction as an external magnetic field. Moreover, plural oriented silicon steel strips are laminated depending on the thickness of the oriented silicon steel strip in use or the strength of the external magnetic field in the applied location or the like to form a multi-layer structure of a shield box main body S. Thus, the material cost is much reduced in comparison with a special material such as a permalloy or an amorphous.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a CRT for protecting a CRT used in a personal computer, a word processor monitor, a home television receiver, etc. from the influence of external magnetic fields. related to magnetically shielded boxes.

(Prior Art) CRTs used in monitors for personal computers, word processors, television receivers for home use, and the like are affected by external magnetic fields from generators, motors, trains, elevators, and the like.

When a CRT is influenced by magnetism, disturbances such as blurring occur on the CRT screen.

This phenomenon occurs when an external magnetic field is applied to the electron beam emitted from the CRT's electron tube, causing the electron beam to bend according to Fleming's left-hand rule, following a different trajectory than the original, and causing the bright spot to shift. It is said that a pre-phenomenon occurs.

In addition, to prevent such effects of external magnetic fields on CRTs, it is possible to solve the problem by blocking the external magnetic fields, but it is currently considered extremely difficult to completely block the external magnetic fields. This is being addressed by strengthening the shielding of external magnetic fields as much as possible.

In other words, in the past, a shield box was formed from a special material with high magnetic permeability, specifically a material such as permalloy or amorphous, and by storing a CRT in this shield box, it could be used to power generators, motors, trains, elevators, etc. This is dealt with by bypassing external magnetic fields such as these to some extent.

(Problem to be solved by the invention) However, materials such as permalloy and amorphous are expensive and difficult to process, resulting in a significant increase in the cost of the product, and in some cases, the cost of storing C
A sealed box may be more expensive than an RT.

For example, compared to the grain-oriented silicon steel strip used in the present invention, Beherma is commercially available at a price approximately 25 times higher, and amorphous is commercially available at a price approximately 15 times higher, and amorphous is extremely difficult to process due to its characteristics. It has become a thing.

For these reasons, conventional magnetically shielded boxes made using special materials such as permalloy and amorphous have to be expensive, and as a result, they cannot be used for word processors, personal computers, or home use. Magnetically shielded boxes are more expensive than the various devices associated with CRTs that are housed in magnetically shielded boxes, such as television receivers, and this has hindered the spread of this type of shielded box in the market. ing.

(Means for solving the problems) The present invention addresses the above problems, and includes:
A grain-oriented silicon steel strip, which is extremely inexpensive compared to special materials such as permalloy or amorphous, is used, and the grain-oriented silicon steel strip is bent 1. The ceiling plate part 1, the left and right side walls 3.4, and the bottom plate 1 are formed in a continuous manner, and the front side is an opening part 9. In addition, the starting end and the terminal end of the grain-oriented silicon steel strip are formed. Butt part B
is located in the same direction as the magnetic field direction of the external magnetic field.

In addition, the shield box main body S has a multilayer structure by laminating a plurality of grain-oriented silicon steel strips depending on the thickness of the grain-oriented silicon steel strip used or the strength of the external magnetic field at the place of use. Furthermore, in order to improve the strength of the product, a frame body 6.1 is attached to the front end of the grain-oriented silicon steel strip that constitutes the shield box main body S, and reinforcement is added to the bottom plate part 2. Board 8
It is characterized by the addition of.

(Function) By taking such measures, the present invention bypasses the external magnetic field to the shield box main body S, and the C
It has almost no effect on RT.

In addition, multiple grain-oriented silicon steel strips are polymerized to create a multilayer structure.
By locating the abutting portion B of at least one layer in the same direction as the magnetic field direction of the external magnetic field, and locating the abutting portion B of the other layer at a different location, it is possible to cope with changes in the magnetic field direction of the external magnetic field. obtain.

(Embodiment) An embodiment of the present invention will be described with reference to the accompanying drawings. Reference numeral 1 indicates a ceiling plate part, 2 a bottom plate part, 3.4 left and right side wall plate parts,
These are made by polymerizing grain-oriented silicon steel strips into three layers.
Each has a gentle curvature, specifically the innermost radius of 3
It is continuously arranged by a curved part A formed in mm, and the starting end and the terminal end of the grain-oriented silicon steel strip are brought into contact to form an abutting part B.

In other words, three grain-oriented silicon steel strips are overlapped and bent at a predetermined gentle curvature to form the curved section A, and the ceiling plate section 1 is sequentially formed through the curved section A. , the left and right side walls 3.4 and the bottom plate part 2 are formed, the starting end and the terminal end of the grain-oriented silicon steel strip are brought into contact with each other to form an abutting part B, and the front side is made into an opening 9 to form a shield box main body S. ing.

In the case of this embodiment, the abutting part B of the outer and inner layers of the polymerized grain-oriented silicon steel strip is located at the bottom plate part 2, and the abutting part B of the middle layer is located at the ceiling plate part 1. However, the abutting portion B of at least one layer must be located in the same direction as the magnetic field direction of the external magnetic field.

This is because the magnetic permeability of the grain-oriented silicon steel strip used in the present invention decreases due to deformation of the internal structure due to extreme bending or cutting, and naturally the magnetic permeability decreases at the butt portion B. Therefore, it is necessary to position at least the abutting portion B in the same direction as the magnetic field direction of the external magnetic field.

For example, when the magnetic field direction of the external magnetic field is substantially vertical, the abutting portion B must be located on the ceiling plate portion 1 or the bottom plate portion 2.

However, in the case of a multi-layer structure as in this example, the butt part B of the grain-oriented silicon steel strip used in any one of the layers is located in the ceiling plate part 1 or the bottom plate part 2. Just let it happen.

In addition, the reason why the grain-oriented silicon steel strip is made into three layers in this example is that the grain-oriented silicon steel strip used is JIS35P115, and the overall thickness is set to about 1 mm. This is due to

In other words, the JIS35P115 grain-oriented silicon steel strip has a thickness of 0.35 m+n, and by forming three layers of these, a total thickness of 1.05 mm is ensured.

As for the overall thickness, there is no problem as long as it is set appropriately, taking into account the strength of the external magnetic field that affects the CRT, etc., and it is quite conceivable that a minus layer is sufficient.

5 is a back plate portion, and the back plate portion 5 stores C.
A wiring hole 11 for passing cords connecting the RT and peripheral devices, and a heat dissipation slit 10 are formed.

The material of this back plate portion 5 is not particularly limited, and synthetic resin materials, wooden plywood, etc. may be used, but if a grain-oriented silicon steel strip is used like the shield box main body S, it can be easily removed from the back side. It is also effective to some extent against external magnetic fields.

Reference numeral 6.7 denotes frames attached to the front and rear of the shield box main body S, which are made of wood in this embodiment, and this frame 6.7 improves the overall strength.

In other words, depending on the thickness of the grain-oriented silicon steel strip, the shield box body S alone may not be able to provide sufficient strength against external impact or pressing force. The total thickness of the grain-oriented silicon steel strip is approximately 1
If it is about nun, it is better to attach the frame 6.7.

[This is a reinforcing plate made of synthetic resin such as Idak or wooden plywood, and the reinforcing plate 8 is fixedly installed on the bottom plate part 2.

This is because when the frame 6.7 is attached and installed on a desk, the frame 6.7 is in contact with the desk surface, but the bottom plate 2 is supported in the air, and the CRT to be stored is It is assumed that there may be a situation in which the load cannot be withstood, and in order to cope with such a situation, the reinforcing plate opening is fixedly installed on the upper surface of the bottom plate portion 2.

Reference numeral 12 denotes an appropriate number of support legs fixed to the lower surface of the bottom plate 2. The support legs 12 are made of a material having appropriate elasticity such as rubber, and together with the reinforcing plate opening, support the bottom plate 2. It is arranged to deal with pressure.

Therefore, when using the magnetically shielded box of the present invention, it is necessary to measure the external magnetic field that is affecting the location where the CRT is installed, check the characteristics of the CRT to be installed, and check the strength of the external magnetic field. Select a magnetic shield box with a corresponding thickness, that is, the number of laminated grain-oriented silicon steel strips set in response to external magnetism, and determine its installation position while also considering the magnetic field direction of the external magnetic field. It is said that

(Effects of the Invention) The present invention bends a grain-oriented silicon steel strip at bending portions A perpendicular to the rolling direction to form a ceiling plate portion 1, left and right side wall portions 3.4.
and a bottom plate part 2 are formed in series, and the front side is an opening S. In addition, in addition to these, the abutting part B between the starting end and the terminal end of the grain-oriented silicon steel strip is formed in the direction of the magnetic field of the external magnetic field. In addition, depending on the thickness of the grain-oriented silicon steel strip used or the strength of the external magnetic field at the location of use, multiple grain-oriented silicon steel strips are laminated to form a shield. The box body S has a multilayer structure, and in order to further improve the strength of the product, a frame 6.7 is attached to the front end of the grain-oriented silicon steel strip that makes up the shield box body S. And again,
Since it is characterized by the addition of a reinforcing plate to the bottom plate part 2, the material cost can be kept low compared to special materials such as permalloy or amorphous, and as a result, the magnetic shield box itself can be marketed. Can be provided at low cost.

In addition, this is a grain-oriented silicon steel strip that is much cheaper than permalloy or amorphous, but by configuring it as described above, magnetic shielding boxes manufactured using permalloy or amorphous, which have been seen here and there, can be used. Even when compared to the above, it exhibits various effects that are extremely useful in practice, such as exhibiting a shielding ability that is equivalent to or greater than that against external magnetism.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view seen from the front side, FIG. 2 is a perspective view seen from the back side, FIG. 3 is a rear view, and FIG. 4 is a perspective view seen from the front side. The X-ray sectional view and FIG. 5 are partially omitted enlarged longitudinal sectional views of the shield box main body S. Code Table 1 Ceiling panel 2 Bottom panel 3 Left wall 4 Right wall 5 Rear panel 6.1 Frame opening Reinforcement plate S Opening 1 (I Heat dissipation slit 11 Wiring hole 12 Support leg A Curved Part B Butt part S Shield box main body Figure 1

Claims (5)

[Claims] (1) A grain-oriented silicon steel strip is bent at the bending part A perpendicular to the rolling direction to form a ceiling plate part 1, left and right side walls 3 and 4, and a bottom plate part 2 in series, and the front side is A magnetic shield box for CRT characterized by having an opening 9. (2) A grain-oriented silicon steel strip is bent at a bending part A perpendicular to the rolling direction to form a ceiling plate part 1, left and right side walls 3 and 4, and a bottom plate part 2 in series, and A magnetic shield box for a CRT, characterized in that an abutting part B between a starting end and a terminal end of a raw steel strip is located in the same direction as the direction of an external magnetic field, and the front side is an opening 9. (3) A magnetic shielding box for a CRT according to claims 1 and 2, characterized in that the shielding box main body S is formed by laminating a plurality of grain-oriented silicon steel strips to form a multilayer structure. . (4) The frames 6 and 7 are attached to the front end of the grain-oriented silicon steel strip constituting the shield box main body S, according to claims 1 to 3. Magnetic shield box for CRT. (5) A magnetically shielded box for CRT according to claims 1 to 4, characterized in that a reinforcing plate 8 is attached to the bottom plate portion 2.