Cathode-ray tube device

Abstract

The cathode ray tube apparatus comprises a main lens constructed by focus, intermediate, and final acceleration electrodes. The main lens includes a focusing area positioned in a side of the focus electrode, and a diverging area positioned in a side of the final acceleration electrode. A focusing force curve expressing the focusing force along the tube-axis direction in the focusing area has two convex parts respectively being at first and second levels, and a concave part provided between the convex parts and being at a third level sufficiently lower than the first and second levels.

Description

technical field [0001] The present invention relates to a cathode ray tube device including an electron gun for emitting one or more electron beams, and more particularly to a cathode ray tube device which improves the focusing characteristics of the electron beams and obtains high definition in the entire screen area. Background technique [0002] Generally, in a color cathode ray tube device, the three electron beams emitted by the electron gun are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection device, and the deflected electron beams pass through the shadow mask and shoot to the phosphor screen composed of three-color phosphor layers Use the electron beam to scan the fluorescent screen horizontally and vertically, and display color images on the fluorescent screen. [0003] Among such cathode ray tube devices, especially a self-converging (Converge) in-line color cathode ray tube device is the main type of the current catho...

AI Technical Summary

Problems solved by technology

However, if the electron gun is designed so that the distance between the three electron beams is relatively large, there will be a problem that the convergence characteristics of the three electron beams will be deteriorated.

[0014] However, only with such a structure, compared with the horizontal direction, the lens magnification and spherical aberration in the vertical direction are very large, and the diameter of the electron beam spot in the vertical direction is also larger than that in the horizontal direction. The spots become vertically elongated, and the sharpness of the center of the screen decreases

Especially when the size or deflection angle of the cathode ray tube device is large, the lens magnification and spherical aberration in the vertical direction are increased, and the resolution is significantly reduced.

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