| 摘要 |
<p>A set of photoelectric transducers, optically scanning a line transverse to the direction of movement of a character-bearing document to be electronically read, is periodically actuated to pick up light from a multiplicity of elemental areas of that document and to generate electrical analog voltages commensurate with the brightness of these areas. The analog voltages are serially read out from one or more shift registers as a pulse train or several parallel pulse trains each undergoing digitization and subsequent storage in respective cells of an associated memory. A group of these cells contain, at a given instant, digital codes representative of the relative brightness of respective elemental areas othogonally arrayed in a square surface portion of the document divided into a middle zone and four diagonally adjoining peripheral zones, the middle zone being centered on the point currently scanned. The relative brightness of that scanned point is weighted by an adaptive field function, based on the relative brightness of the peripheral areas, to yield a responsive parameter whose joint evaluation with the relative brightness of the scanned point yields a binary output signal. A series of such output signals, derived from simultaneous readings of a corresponding number of adjoining transducers, is converted into a multibit word fed to a utilization circuit.</p> |
