Charactron

Charactron 

a cathode-ray tube used in information display units to reproduce letters, numbers, map symbols, and other characters. Invented in the USA in 1941, the Charactron is an instantaneous-operation numerical indicator tube.

In the Charactron, the characters reproduced on the tube’s screen are formed by means of a matrix, which is an opaque plate containing a set of 64 to 200 microscopic openings in the shape of the characters to be displayed. The matrix is located in the path of the electron beam between two deflection systems. The first deflection system guides the beam to the desired character on the matrix; the second system guides the shaped beam to the desired location on the screen. When the beam passes through the matrix, the cross section of the beam takes on the shape of the character through which it has passed. Hence, an image of the desired character—rather than a point, as in ordinary cathode-ray tubes—is illuminated at the place where the beam strikes the screen.