US 4,047,152 A · Electronic character-reading system

Abstract

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.

Claims15

Dependent claims

A method of electronically reading characters on a carrier moving unidirectionally past a set of photoelectric transducers positioned to scan the carrier surface along a line substantially perpendicular to the direction of carrier motion, said transducers generating individual signal voltages commensurate with the brightness of respective elemental areas of the carrier surface optically registering therewith at a given instant, comprising the steps of:

establishing a succession of operating cycles of a duration so chosen that the advance of said carrier during each cycle is on the order of magnitude of the width of an elemental area as measured along said line, each of said cycles being divided into a multiplicity of phases;
deriving from said signal voltages and from a reference voltage a set of electrical quantities representative of image contrasts existing at said elemental areas;
storing, during each phase, the electrical quantities derived from the signal voltages of a plurality of said transducers optically registering with a two-dimensional array of elemental areas on said carrier, said array including a first zone containing a central elemental area and a second zone composed of several peripheral elemental areas;
separately weighting different groups of stored electrical quantities, relating to elemental areas of said first zone and of said second zone, with a contrast-enhancing field function;
and
evaluating the most significant electrical quantity stored during any phase, relating to said central elemental area, together with a response parameter synthesized from the weighted electrical quantities to produce a binary output signal.

3 more elements

A system for electronically reading characters on a unidirectionally moving carrier, comprising:

scanning means including a set of photoelectric transducers;
optical means adjacent the path of said carrier for illuminating said transducers with light from respective elemental areas of the carrier surface adjoining one another along a line substantially perpendicular to the direction of carrier motion, said transducers generating individual signal voltages commensurate with the brightness of said respective elemental areas;
timing means establishing a succession of operating cycles of a duration so related to the speed of said carrier that the advance of said carrier during each cycle is on the order of magnitude of the width of an elemental area as measured along said line, each of said cycles being divided into a multiplicity of phases;
conversion means connected to said scanning means and to a source of reference voltage for translating said signal voltages into electrical quantities representative of image contrasts existing at said elemental areas;
memory means connected to said conversion means and controlled by said timing means for storing, during each phase, the electrical quantities derived from the signal voltages of a plurality of said transducers illuminated by a two-dimensional array of said elemental areas, said array including a first zone containing a central elemental area and a second zone composed of several peripheral elemental areas;
first and second arithmetic means connected to different stages of said memory means for extracting first and second stored electrical quantities relating to elemental areas of said first zone and said second zone, respectively, and weighting the extracted quantities with a contrast-enhancing field function;
evaluation means connected to said first and second arithmetic means for synthesizing a response parameter from the weighted electrical quantities;
and
readout means extending from said memory means to said evaluation means for feeding thereto the most significant electrical quantity stored in any phase, relating to said central elemental area, for conversion into a binary output signal under the control of said response parameter.

6 more elements

Dependencies are inferred from the claim text.

Electronic character-reading system

Life of this patent

Electronic character-reading system

Life of this patent

Abstract

Claims15