Inner cover of colour cathode ray tube

Abstract

A color CRT having an inner shield being mounted at a frame inside a panel and a funnel to shield an earth magnetic field, in which the inner shield comprises: a vertical portion formed in parallel to the central axis of the CRT and mounted at the frame, a slope portion extended slanted against the central axis of the CRT at a rear side of the vertical portion and a notch with its central portion formed concave at the end portion of the slope portion, the opposite of the frame; and on the assumption that the shortest height from a starting point of the vertical portion to the notch is V2, the height V1 of the vertical portion satisfies a relational expression of 0.40<=V1 / V2<=0.54. By reducing the variation degree that the electron beam is landed is according to the external magnetic field variation, when an image is reproduced, a color spread phenomenon due to a color mixture is prevented from occurring. In addition, since the color spread phenomenon due to a color mixture is prevented, the inner shield contributes to obtain a high image quality, and thus, a reliability of its product is improved.

Description

[0001] This application is a divisional application of the invention patent application filed on October 30, 2001 by LG Electronics Co., Ltd. with the name "Color CRT Inner Cover" and application number 01137566.3. technical field [0002] The present invention relates to a color cathode ray tube, and in particular to an inner cover of a color cathode ray tube. By improving the structure of the inner cover, the shielding effect can be improved, and due to the improved shielding effect, the electrons related to the change of the external magnetic field can be reduced. The degree of variation of the beam landing point can prevent color diffusion caused by color mixing when reproducing images. Background technique [0003] figure 1 Is a partial side view showing the internal structure of a cathode ray tube, including an inner cover made by conventional techniques. Figure 2A with Figure 2B Respectively, the rear view and the plan view show the inner cover made by this tradit...

AI Technical Summary

Problems solved by technology

[0015] For example, compare Figure 2B , because the height (h1) of the vertical portion 62 is too small for the height (H) of the inner cover 60 formed by the vertical portion 62 and the slope portion 63, the slope portion 63 is separated from the cone 20 by a large distance (d), resulting in Reduced effectiveness of shielding the Earth's magnetic field

[0016] When the inner cover 60 is used for a color cathode ray tube product and used for a period of time, since the efficiency of shielding the earth's magnetic field decreases, the degree of variation of the landing point of the electron beams related to the change of the external magnetic field becomes large, resulting in a Color Bleeding Problems Due to Color Mixing When Reproducing Images

[0017] When color diffusion occurs due to these factors, the value of cathode ray tube products pursuing high image quality decreases, and the reliability of products decreases accordingly

Images