Deflection yoke having magnets for correcting raster distortion and cathode-ray tube apparatus having the deflection yoke
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorKatsuyo Iwasaki
Life of this patent
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Abstract
A permanent magnet is selectively picked for a deflection yoke and provided on the periphery of the cathode ray tube for controlling the direction of an electron beam emitted towards a screen from an electron gun. The permanent magnet can adjust an irradiating point of the electron beam. The permanent magnet incorporates a magnetic substance that can be applied to at least one of the end faces of the magnet with a negative temperature characteristic. The magnetic substances can have different configurations and based on the saturation flux density of the permanent magnet, can be selected to match the permanent magnet to correct variation in the saturation flux density.
Claims19
A deflection yoke provided on a periphery of a cathode-ray tube, the deflection yoke applying a deflection magnetic field to an electron beam emitted towards a screen from an electron gun which is mounted in a neck of the cathode-ray tube, thereby controlling the electron beam to scan across the screen, including:
- a magnet for adjusting an irradiated point of the electron beam on the screen;
- and
- a magnetic substance whose permeability changes with a negative temperature characteristic being attached on at least one of both end faces of the magnet which are S and N poles respectively.
A cathode-ray tube apparatus comprising:
- a cathode-ray tube including a panel which contains a screen inside, a neck which mounts an electron gun positioned opposite to the panel, and a funnel which joints the panel and the neck, wherein
- an electron beam is emitted from the electron gun towards the screen;
- and
- a deflection yoke provided on a periphery of a cathode-ray tube, the deflection yoke applying a deflection magnetic field to an electron beam emitted towards a screen from an electron gun which is mounted in a neck of the cathode-ray tube, thereby controlling the electron beam to scan across the screen, wherein
- the deflection yoke includes:
- a magnet for adjusting an irradiated point of the electron beam on the screen;
- and
- a magnetic;
- substance whose permeability changes with a negative temperature characteristic being attached on at lease one of both end faces of the magnet which are S and N poles respectively.
A method for improving raster in a cathode-ray tube having a deflection yoke comprising the steps of:
- selecting a permanent magnet;
- determining a saturation flux density for the permanent magnet that is to be operatively mounted relative to the deflection yoke;
- providing a plurality of individual magnetic substance members of different configurations;
- selecting a pair of magnetic substance members of the same configuration from the plurality of individual magnetic substance members to correct any variation in the saturation flux density of the selected permanent magnet to within an approximate range of plus or minus 1000 μTeslas;
- and
- mounting the selected pair of magnetic substance members to the permanent magnet.
Dependencies are inferred from the claim text.