OPTICAL CHARACTER READER HAVING FEATURE RECOGNITION CAPABILITY

• US 3,868,636 A
• Filed: 06/18/1973
• Issued: 02/25/1975
• Est. Priority Date: 06/18/1973
• Status: Expired due to Term

• Current Assignee: Arthur Schlang
• Original Assignee: Arthur Schlang
• Inventors: Schlang, Arthur
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Boudreau, Leo H.
• Application Number:
  US05/371,163
• Time in Patent Office: 617 Days
• Field of Search: 340/146.3AC,146.3J,146.3AG,146.3H,146.3ED,146.3R,146.3Y
• US Class Current: 382/193
• CPC Class Codes: G06V 10/10 Image acquisition document image scanning and transmission H04N1/00; control of digital cameras H04N23/60
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/146 Aligning or centring of the image pick-up or image-field
• CPC Class Codes: G06V 30/184 by analysing segments intersecting the pattern

Abstract

The invention is applicable to single line, multiple line and page reading applications. An optical character reader includes an electro-optical sensor for scanning a line of graphic characters on a character bearing medium to derive electrical signals corresponding to configurations of the characters. A sensor processor amplifies the signals, quantizes the amplified signals and correlates them to reduce the effects of optical noise. A feature generation circuit including a plurality of feature data generators applies predetermined tests to determine the presence or absence of specified character features and forwards corresponding feature data signals to an algorithm circuit. The algorithm circuit applies predetermined criteria to the feature data signals according to truth tables set up for the several forms of characters recognizable by the system, to identify the characters being read. The algorithm circuit produces decimal data which is fed to a decimal to binary converter.

Claims

1. An optical character reader for optically reading characters of a font of two dimensional plane characters based on an ideal regular plane matrix of two mutually perpendicular sets of linear strokes comprising:

a plurality of electro-optical sensor means arranged consecutively in an array, which is disposed to scan said characters one at a time while said characters are moved relative to said array in a direction of movement perpendicular to said array in the plane of said matrix and parallel to one of said sets of strokes and, to produce electrical signals corresponding to configurations of said characters, sensor processing means in circuit with said sensor means and arranged to amplify said signals, quantize said amplified signals, and correlate said quantized signals to reduce effects of optical noise, a feature generator means connected to said sensor processing means and arranged to apply several predetermined tests to determine the absence or pResence of certain specified features;

said feature generator means comprising;

a first circuit means for determining the height of said characters;

a logic circuit means for counting the number of times each of said electro-optical sensor means detects one or more of the strokes parallel to said array of said characters as said characters longitudinally traverse said sensor means; and

a count sequence circuit means connected to said first circuit means and said logic circuit means for determining the consecutive number of said electro-optical sensing means which have counted the same number of strokes, parallel to said array of said characters; and

an algorithm circuit in circuit with said feature generator means for applying predetermined criteria to data communicated therefrom, to ascertain the identity of said characters being read.

2. An optical character reader as recited in claim 1 further including a scan means for providing that an image of each of said characters moves in said direction while it is scanned in a second direction orthogonal to said direction by said sensor means and wherein said scan means includes means for scanning all of said electro-optical sensor means at least once each time said images moves the width of one of said electro-optical sensor means.

3. An optical character reader as recited in claim 1 wherein said sensor processing means includes a leading edge signal means for producing a single leading edge signal in response to electric signals from at least two consecutively positioned sensor means and wherein said feature generator means includes a counting circuit means connected to said leading edge signal means which counts of said leading edge signal.

4. An optical character reader as recited in claim 3 wherein said counting circuit means is connected to a counting logic means for counting said leading edge signals only if a subsequent scan has a greater number of leading edge signals than the preceding scan.

5. An optical character reader as recited in claim 3 wherein said counting circuit means is connected to a logic circuit means for determining whether the last scan of a character has only one leading edge.

6. An optical character reader as recited in claim 4 further including zonal circuit means for dividing the height of said character image into a plurality of zones and a processing circuit means coupled to said zonal circuit means and said counting logic means for determining the zone of said leading edge.

7. An optical character reader as recited in claim 4 further including longitudinal division circuit means connected to said counting logic means for determining the longitudinal section of said leading edges.

8. An optical character reader as recited in claim 3 further including a saddle circuit means connected to said leading edge signal means of said sensor processing means for determining whether said character image has a fall which exceeds a percentage of said character height and is followed by a rise that exceeds said percentage of said character height.

9. An optical character reader comprising:

a plurality of electro-optical sensor means arranged consecutively in an array and disposed for scanning a plurality of graphic characters on a medium, one at a time while said characters are moved relative to said array in a direction of movement perpendicular to said array to derive electric signals corresponding to configurations of said characters;

a scan means for providing that an image of each of said characters moves in said direction while it is scanned in a second direction orthogonal to said direction by said sensor means;

a sensor processing means connected with said sensor means and arranged to amplify said signals, quantize said amplified signals, and correlate said quantize signals to reduce effects of optical noise, said sensor processing means including a leading edge signal means for producing a single leading edge signal in response to electric sIgnals from at least two consecutive sensor means;

a feature generator means connected to said sensor processing means and arranged to apply several predetermined tests to determine the absence or presence of certain specified features;

said feature generator means comprising;

a counting circuit means connected to said leading edge signal means which counts said leading edge signal; and

an algorithm circuit connected with said feature generator means and for applying predetermined criteria to data communicated therefrom to ascertain the identity of said characters being read.

10. An optical character reader as recited in claim 9 wherein said counting circuit means is connected to a counting logic means.

11. An optical character reader as recited in claim 9 further comprising:

a means for illuminating said characters on said medium while they are being scanned; and

an automatic gain control means in said sensor processing means arranged to correct for variations in illumination of said characters in surface reflectance of said medium, and in light absorptivity of graphic characters.

12. An optical character reader as recited in claim 9 wherein said feature generator means further includes a plurality of feature data generator circuits arranged to receive processed signals from said sensor processing means corresponding to configurations of said scanned characters, each one of said feature data generator circuits being responsive to said processed signals and arranged to generate data signals corresponding to at least one predetermined character feature selected from the following group of character features:

character height, horizontal strokes, final value, vertical strokes, saddle, character width, upper stroke slope, blobs and smudges, precipitous fall, final 1 count, and third stroke slope.

13. An optical character reader as recited in claim 9 further comprising adjustment means arranged to move said medium in one of said directions to position characters on said medium in an optimum position for being scanned by said electro-optical means.

14. An optical character reader as recited in claim 9, wherein said algorithm circuit, comprises separate logic circuits, one for each preferred form of character to be read, each one of said logic circuits containing components arranged to correlate data signals received from said feature data generator circuits with different character forms each defined by a corresponding truth table.

15. An optical character reader as recited in claim 14, wherein each of said logic circuits produces decimal data corresponding to character forms recognized by said algorithm circuit and further comprising a decimal to binary conversion circuit connected to said algorithm circuit for producing binary data signals corresponding to the character forms recognized by said algorithm circut.