Cathode-ray tube having a substantially flat face panel

Abstract

The present invention relates to a cathode-ray tube having: (1) a face panel; (2) a phosphor screen; (3) a funnel coupled to the face panel; and (4) an electron beam emitter. The outer surface of the face panel is defined by using orthogonal coordinates. An origin of the orthogonal coordinates is defined as a center of the outer surface of the face panel. An X-axis of the orthogonal coordinates is defined as a horizontal axis. A Y-axis of the orthogonal coordinates is defined as a vertical axis. A Z-axis of the orthogonal coordinates is defined as the central axis of the funnel. The Z coordinate for points on the outer surface of the face panel are defined by the polynomial: ##EQU1## wherein i and j are integers .gtoreq.0, n=2, and aij are predetermined coefficients of the polynomial. The predetermined coefficients along the X-axis are represented by a.sub.10 and a.sub.20, and coefficients along the Y-axis are represented by a.sub.01 and a.sub.02. The coefficients a.sub.10, a.sub.20, a.sub.01, and a.sub.02 satisfy the relationships: (1) a.sub.20 /a.sub.10 <0.1.times.10.sup.-6 ; and (2) a.sub.02 /a.sub.01 <0.1.times.10.sup.-6. The remaining coefficients are selected so that an external light image is not distorted when reflected from the outer surface of the face panel.