JPH01140541A - Image display device - Google Patents

Abstract

PURPOSE:To prevent the influence of the external magnetism by covering a CRT with a superconductor. CONSTITUTION:The side surfaces of a cathode-ray tube 1 are covered with magnetic shields 2 of a superconductor, and the surface of a display is covered with a magnetic shield 3 of a light permeable type membrane. In a superconductive condition, the superconductor presents a perfect anti-magnetic property, and it is not collapsed until the critical magnetic field is reached. Consequently, by forming the magnetic shields 2 and 3 with a superconductor of a large critical magnetic field, a correction device to the external magnetic field is not necessary to provide, and the structure can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image display device in which a cathode discharge tube is covered with a superconductor.

[Prior Art] In a conventional image display device using a cathode discharge tube (CRT), electrons are emitted from an electron gun inside the cathode discharge tube toward the display section of the cathode discharge tube, and electrons are placed outside the cathode discharge tube. Characters and images are displayed by changing the flight direction of electrons using the magnetic field generated by the electromagnetic coil, and by irradiating the electrons onto the fluorescent material in the display section.

However, in such devices, the flight direction of the electrons is controlled by the magnetic field from the electromagnetic coil installed outside the cathode discharge tube, as described above, so they are easily influenced by external magnetism and cannot produce clear images. 6 For example,
In image display devices used in measuring instruments and the like, distortion occurs in waveform traces due to the influence of external magnetism, so there is a problem in that a circuit must be added to adjust the rotation of the traces.

Furthermore, in color televisions and the like, color blurring occurs in images due to the influence of magnetism from coils of speakers and the like. Furthermore, when color televisions are made larger, there is a problem in that color unevenness occurs in images due to the influence of the earth's magnetic field.

[Object of the Invention] An object of the present invention is to provide an image display device that eliminates the influence of external magnetism by covering a cathode discharge tube with a superconductor.

[Summary of the Invention] The gist of the present invention to achieve the above object is to provide an image display device using a cathode discharge tube, in which the cathode discharge tube is completely covered with a superconductor, and at least the cathode discharge tube is covered with a superconductor. This image display device is characterized in that the surface of the display section is covered with a thin film-like superconductor that is transparent to light.

[Embodiments of the invention] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a perspective view of the present invention, in which the side surface of the cathode discharge tube 1 is covered with a magnetic shield 2 made of a superconductor, and the surface of the display section of the cathode discharge tube 1 is covered with a magnetic shield 3 made of a superconductor.
It has a structure covered with Note that the magnetic shield 3 is a thin film that is transparent to light. In addition, in a superconducting state, a superconductor exhibits perfect diamagnetic property with zero magnetic permeability, that is, the Meissner effect, and has a perfect magnetic shielding effect because lines of magnetic force do not pass through it. Note that the magnetic shield 3 that is transparent to light and covers the surface of the display section of the cathode discharge tube 1 may be formed by forming a thin film of a superconductor using a vacuum deposition technique.

In the image display device configured in this way, even if an external magnetic field is applied, the magnetic shield 2.3 does not allow the lines of magnetic force caused by the external magnetic field to pass through, so the cathode discharge tube 1 is not affected by the external magnetic field. The image of the cathode discharge tube 1 becomes clear without color bleeding. Furthermore, superconductors exhibit complete diamagnetic properties in the superconducting state, and superconducting states do not collapse up to the critical magnetic field. Therefore, if the magnetic shield 2.3 is formed of a superconductor with a large critical magnetic field, it is possible to The image display device according to the present invention can be installed near a device that generates a strong magnetic field, such as a device that uses magnetic resonance (NMR), which significantly increases the degree of freedom in terms of installation location and usage form. There is an effect.

Furthermore, by applying a magnetic shield made of a superconductor, the image display device according to the present invention eliminates the need for a correction mechanism for external magnetic fields, which is provided in conventional image display devices using cathode discharge tubes, and the structure can be simplified.

[Effects of the Invention] As explained above, the image display device according to the present invention can eliminate the influence of an external magnetic field on the cathode discharge tube by covering the cathode discharge tube with a superconductor.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of an image display device according to the present invention. The symbol 1 is a cathode discharge tube, and 2.3 is a magnetic shield. Patent applicant Canon Co., Ltd. Figure 1

Claims (1)

[Claims] 1. In an image display device using a cathode discharge tube, the cathode discharge tube is entirely covered with a superconductor, and at least the surface of the display portion of the cathode discharge tube is covered with a thin film-like superconductor that is transparent to light. An image display device characterized by being covered with a conductor.