1. An illuminated sign designed to be viewed from a horizontal line of sight of an observer, the light box comprising: a frame having a width; a partially transparent face supported thereon; a single or plurality of lengthwise sections of luminous tubing mounted in the frame and having a tubing inside radius (r) and an inner surface having a reflector-closest edge, and; a single or plurality of concavely-curved, reflective channels each having an angle of wrap (&bgr;) and a concave surface having a tubing-closest edge positioned at a distance (d) from the tubing inner surface reflector-closest edge; a reflective channel having a substantially semi-cylindrical shape with a radius of curvature (R) wherein the improvement comprises each said reflective channel having an actual angle of wrap (&bgr;a) approximately equal to about 70% to about 150% of a calculated value for &bgr;c which solves an equation consisting of: 4 1 sin &it; ( β &it; &it; c 2 ) + 2 &it; ( R r - d r - 1 ) &it; cos &it; ( β &it; &it; c 2 ) = R r.