Letter spacing in photo type setting - is determined by photo-electric reading of letter width window

摘要

The printing symbols are provided on a disc having adjacent each symbol a window whose width is equal to the width of the symbol. The printing paper is moved relative to the projection axis so as to stop when is register for projection of a given symbol. The movement of the paper in respect of the next symbol is accompanied by a photo cell which reads the width of the window of the previous symbol. The photo cell is mounted on a slide connected to return to a zero position on completion of the paper movement pertaining to any one symbol.