Patent US 4,246,570

An optical wand for automatically recognizing characters in a plurality of fonts incorporates a manually movable scanner incorporating a light source and a sensor array composed of a diode matrix. A first preprocessing unit is connected to receive the output from the scanner, and includes a correlation unit for buffering the data and apparatus for eliminating the effect of different characteristics of the individual photo diodes. The first preprocessing unit also includes a row tracking circuit and a segmentation circuit for presegmenting and for centering the character. Further segmentation, and filtering of the image is carried out by a second preprocessing unit which is decoupled from the first preprocessing unit, so that its operation is concurrent with that of the scanner. A recognition unit, decoupled from the second preprocessing unit, is connected thereto, and establishes individual values for the scanned characters by use of a quadratic polynomial classifier.