Abstract: Variations in scan rate and in position of a character within a field resulting from positional inaccuracies caused by use of a hand-held scanning device and/or loosely constrained document printing mechanisms and techniques are accommodated by sweeping a two-dimensional sensing array of about one character width and several character heights horizontally along a line across the field and applying a matrix of output signals resulting from each character to a recognition unit. Each set of signals is shifted vertically through the recognition unit at a rate such that all cells of the array are scanned in an interval required for movement of the field on the array of less than one resolution cell. Character recognition is attempted for each one-cell-height increment that the set is vertically shifted. A recognition output signal is produced when a character in the shifted set is brought into registration with a set of inputs leading to the recognition unit.

Abstract: An optical data reader and processor utilizing a two dimensional array of photosensitive elements operated at a high frame rate; a shift register of one character width, and greater than one character height to store the binary representation of the character image; unique black/white threshold detection and character recognition logical circuitry; and timing means to overcome inaccuracies arising from the loosely constrained movement of a hand-held scanning device.