PURPOSE: To provide long-life, uniform luminance with an improved luminance characteristic by a superir convergence characteristic, by utilizing a fluorescent character display tube having a concave anode with a phosphor material spread over the same.

CONSTITUTION: The fluorescent character display tube 2 is provided with a luminous surface 5 of a phosphor material disposed in a concave form within a glass vessel 6, 7 so that rays of light are converged on an original 1. The phosphor material is caused to emit rays of light by electron bombardment to be generated by a voltage applied between a filament 9 supplying thermoelectrons and an anode 10 of a transparent electrode with the phosphor material spread over the same. The fluorescent character display tube 2 is provided with a light transmitting window 12 for transmitting reflected rays of light by the original 1 to an image sensor 4 and with a convergent transmission element array 3 known as SELFOC, its trade name.