Cathode-ray tube having a substantially flat face panel

A cathode-ray tube comprising:

• a face panel having a substantially rectangular outer surface and an inner surface;
• a phosphor screen which is formed on the inner surface of the face panel;
• a funnel coupled to said face panel;
• and
• an electron beam emitter, disposed in the funnel, constructed and arranged to emit an electron beam toward the phosphor screen;
• wherein said outer surface of the face panel is defined by using orthogonal coordinates, an origin of the orthogonal coordinates being defined as a center of the outer surface of the face panel, an X-axis of the orthogonal coordinates being defined as a horizontal axis passing through the origin and perpendicular to a central axis of the funnel, and a Y-axis of the orthogonal coordinates being defined as a vertical axis passing through the origin and perpendicular to the central axis of the funnel, and a Z-axis of the orthogonal coordinates being defined as the central axis of the funnel;
• wherein a Z coordinate for points on the outer surface of the face panel are defined by the following polynomial:
• ##EQU5## wherein i and j are integers .gtoreq.0, n=2, and aij are predetermined coefficients of the polynomial;
• wherein the predetermined coefficients for determining a surface shape of the outer surface of the face panel along the X-axis are represented by a.sub.10 and a.sub.20, and coefficients for determining a surface shape of the outer surface along the Y-axis are represented by a.sub.01 and a.sub.02 ;
• wherein the coefficients a.sub.10, a.sub.20, a.sub.01, and a.sub.02 satisfy the following relationships:
• a.sub.20 /a.sub.10 <0.1.times.10.sup.-6, and a.sub.02 /a.sub.01 <0.1.times.10.sup.-6 ;
• and
• wherein the remaining coefficients are selected so that an external light image is not distorted when reflected from said outer surface of said face panel.