JPS57126051A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a fluorescent surface having satisfactorily stable calm color by using glass containing neodymium as the face plate glass of the fluorescent surface, and improving the instability of the color of the fluorescent surface by taking advantage of the spectral reflection characteristics of a trichromatic phosphor element group. CONSTITUTION:When glass containing neodymium is used as the face plate glass of a fluorescent surface, the color of the fluorescent surface changes due to vectors (a2), (b2) and (c2) which are developed by the main absorption band of 580nm wavelength and are indicated on the chromaticity diagram, as well as due to vectors (a1), (b1) and (c1) which are developed by the sub-absorption band of 530nm wavelength; the vectors (a1), (b1) and (c1)are sufficiently smaller than the vectors (a2), (b2)and (c2). Prevention of the influences of the vectors (a2), (b2) and (c2)can be achieved by producing vectors reverse to the vectors (a2), (b2) and (c2), that are vectors (-a2), (-b2) and (-c2). When an appropriate quantity of light of about 470nm wavelength contained in the reflected external light is reduced by some measures, the chromaticity point becomes more distant from monochromaticity point (Q2) of about 470nm wavelength along line (beta), which links monochromaticity point (Q2) to chromaticity point (A) of light source (A). As a result, a vector (-a2) is produced, and any change of the color of the fluorescent surface can be almost completely prevented.