JPH01303144A - Crt display device - Google Patents

Abstract

PURPOSE:To interrupt the influence of a magnetic field at a CRT front surface by holding a network made of the fabric with a high magnetic permeability material at the holder of a transparent material and fitting it at the CRT front surface. CONSTITUTION:A side surface 1 is covered with a case made of a ferromagnetic material with a high magnetic permeability and at the front surface, a holder of the transparent material to hold a network made of a fabric-shaped high magnetically permeable material is fitted. Here, the magnetic shield of the side surface and the front surface is coupled in a magnetic circuit. As the material with a high permeability, a permalloy, an iron type amorphous alloy, etc., are used. Thus, a magnetic flux to invade to the internal part of a CRT display device can be suppressed by the high permeability type material of the side surface and the mesh-shaped high permeability material of the front surface. Consequently, the magnetic field given to the CRT can be efficiently shielded and near the magnet to generate a large leaking magnetic field, a CRT display device can be arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic shield for magnetically shielding a CRT from a magnetic field, and particularly to a CRT display device used as part of an NMR imaging device.

[Conventional technology]

The leakage magnetic field of the magnetic field device employed in the NMR imaging apparatus is quite strong and spreads over a wide range, and affects nearby electronic equipment.

In particular, the influence of the magnetic field on a CRT can result in blurred text and color shifts. Recently, as described in Nikkei Electronics, January 12, 1987 (Nα412), pages 173 to 184, efforts have been made to cover the sides of CRT displays with permalloy to suppress the effects of magnetic fields; C considering the magnetic shielding of
RT display devices have not yet been developed.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the magnetic shielding of the front surface of the CRT display device, and has the problem of considerable blurring and color shift. An object of the present invention is to shield the influence of magnetic fields on the front surface of a CRT.

[Means to solve the problem]

The above object is achieved by holding a mesh made of fibers of a high magnetic permeability material in a holder made of a transparent material and attaching it to the front surface of a CRT.

[Effect]

In the CRT display device of the present invention, the side surfaces are covered with a highly permeable magnetic shielding material, and the front surface is further provided with a mesh-like magnetic shielding material. Therefore, the magnetic flux that enters the inside is considerably reduced by the magnetic shielding material, so that effects such as character blurring and color shift that occur on the CRT can be suppressed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. A conventional CRT display device (Fig. 2).

A plastic case covered the sides (3), and the front of the CRT (4) was exposed on the front. The CRT display device (FIG. 1) of the present invention has a side surface (1
) is covered by a case made of a ferromagnetic material with high magnetic permeability.
Attached to the front is a holder (2) made of a transparent material that holds a rope made of a fibrous material with high magnetic permeability. Furthermore, the side and front magnetic shields are connected in a magnetic circuit. As the material with high magnetic permeability, permalloy, iron-based amorphous alloy, etc. are used. According to this embodiment, CR
The magnetic flux penetrating into the T display device can be suppressed by the high magnetic permeability material on the side surfaces and the mesh-like high magnetic permeability material on the front surface.

〔Effect of the invention〕

According to the present invention, since the magnetic field exerted on the CRT can be efficiently shielded, the CRT display device can be installed near a magnet that generates a large leakage magnetic field.

[Brief explanation of the drawing]

FIG. 1 is an external view of a CRT display device according to an embodiment of the present invention, and FIG. 2 is an external view of a CRT display device according to the prior art. 1... A case made of a high magnetic permeability material, 2... A holder made of a transparent material holding a rope made of a fibrous high magnetic permeability material,
3...Plastic case, 4...CRT front. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a display device that displays images on a CRT, the periphery is surrounded by a ferromagnetic material with high magnetic permeability, and a net made of a fibrous ferromagnetic material with high magnetic permeability is made of a transparent material. A CRT display device, characterized in that it is held by a flat holder and attached to the front surface. 2. The CRT display device according to item 1, wherein the front screen is colored black. 3. The CRT display device according to item 1, wherein the ferromagnetic material with high magnetic permeability is a permalloy material or an iron-based amorphous alloy. 4. A CRT display device characterized in that in the magnetic shield structure described in item 1, the side and front magnetic shields are connected in a magnetic circuit manner.