READING APPARATUS

• US 3,582,883 A
• Filed: 10/13/1966
• Issued: 06/01/1971
• Est. Priority Date: 10/13/1966
• Status: Expired due to Term

• Current Assignee: David H Shepard, Howard W. Silsby
• Original Assignee: David H Shepard, Howard W. Silsby
• Inventors: Shepard, David H., Silsby, Howard W.
• Application Number:
  US04/594,962
• Time in Patent Office: 1,692 Days
• US Class Current: 382/206
• CPC Class Codes: G06V 10/20 Image preprocessing
• CPC Class Codes: G06V 30/10 Character recognition

Abstract

Character recognition apparatus wherein portions of the character to be identified are projected to form composite transformed scanning signals. In particular, a logical operation is continuously performed over all scanning lines prior to and including the current scanning line, the logical operation being performed on the entire set of signal elements of the current scanning line and a second set of scanning signals which represent the logical sum of all scanning lines prior to the current scanning line. The projected portions of the character thus constitute certain identifying features, which when combined with other identifying features such as the presence of a character stroke (corresponding to the current scanning line) enable processing circuitry responsive to the transformed scanning signal in the current scanning signal to effect character recognition. Circuitry is also provided for changing the logical operation performed upon the current scan line signal and the second set of signals upon detection of predetermined conditions within the character. In the first mode of operation, the second set of signals is decreased in pulse width to eliminate smudges and the like. During the second mode of operation, the pulse width of the elements of the second set of signals is increased to minimize the effect of breaks in the character strokes.

Claims

1. Apparatus for reading intelligence-bearing items comprising:

means for scanning the area of an item to be read along a plurality of scanning frames and producing current scan signals during each scanning frame characteristic of the item scanned, logic means for continuously performing over all scanning frames including and prior to the current scanning frame logical operations on the whole set of scan signals for each current scanning frame with a second set of signals applied thereto to produce a composite transformed scan signal set output comprising at least one signal element having no more than a single bit per signal element, said composite transformed signal set output being the logical sUm of the constituent signal elements of the whole sets of the scan signal from all of the scanning frames prior to and including each current scanning frame, storage means for delaying said composite transformed scan signal set output of the logic means during each scanning frame to form said second set of signals and applying the same during successive subsequent scanning frames to said logic means in frame coordinated relation with the whole set of current scan signals for such subsequent scanning frames whereby said composite transformed scan signal set output produced during each scanning frame comprises a set of transformed scan signals whose constituent signal elements are essentially horizontal projections of intercepted portions of the item corresponding to shadowlike horizontal projections of the item defining a configuration which is related to but distinguishable from the area of the item to be read, first detection means for detecting preselected intracharacter patterns from at least one of said composite signals, said one composite signal being sometimes utilized before that scanning frame which last intersects the item, and means for recognizing the item to be identified by employing said patterns for providing an output signal indicative of the item recognized.

2. logic means for continuously performing over all scanning frames including and prior to the current scanning frame at least one logical operation on the entire current scanning frame signal and a second signal set to provide a transformed scan signal set for each scanning frame, said transformed scan signal set being a logical function of the current scanning frame signal and all scanning frame signals prior to the current one and comprising a set of at least one signal element having no more than a single bit per element, which element corresponds to a projection of at least a portion of the said character to be identified;

3. The combination recited in claim 2 including second detection means for detecting preselected intracharacter patterns from said current scan signals.

4. decision means responsive to at least one said transformed scan signal set for identifying said character, said one transformed scan signal set sometimes being utilized before that scanning frame which lasts intersects the character being scanned.

5. The combination recited in claim 1 including means for effecting changeover from the first single mode of said logic operations to a second single mode of operation continuous over plural scanning frames when certain conditional events related to the item being scanned are detected.

6. The combination recited in claim 5 wherein means responsive to the changeover means for logically subtracting said current scan signals from the second set of scan signals to produce a composite transformed scan signal in response to the occurrence of said changing.

7. The combination recited in claim 5 including means for diminishing the extent of the second set of scan signals prior to the occurrence of said changing.

8. The combination recited in claim 5 including means for lengthening the extent of the second set of scan signals subsequent to the occurrence of said changing.

9. In character recognition apparatus comprising a line scanner for generating current scan signals when scanning an item, delay means fed by a composite transformed signal comprising a current scan line signal output of the scanner and a second scan signal representing all scan line outputs prior to the current scanning line of the scanner, means defining a first single mode of operation continuous over all scanning lines including and prior to said current scanning line for logically adding each said current scan line signal and second scan signal to continuously produce said composite transformed signal before being fed to said delay means, said transformed signal comprising at least one signal element having no more than a single bit per element and being the logical sum of the signal elements of the current and second scan signals such that the transformed composite signal comprises essentially horizontal portions of the item corresponding to shadowlike horizontal projections of the item defining a configuration which is related to but distinguishable from the area of the item to be read, interpreter means responsive to at least one said composite transformed signal and at least one current scan signal generated from the line scanner to detect preselected intracharacter patterns present within the item, said one composite signal being sometimes utilized before that scanning frame which last intersects the item being scanned, and translator means responsive to said interpreter means for recognizing the item to be identified in accordance with combinations of said patterns and providing an output signal indicative of the item recognized.

10. The combination recited in claim 9 including means effecting changeover from the first to a second single mode of operation continuous over plural scanning lines, and means responsive to said changeover means for logically subtracting the second scan signal output from the current scan signal output to form the composite transformed signal during said second single mode of operation.

11. The combination recited in claim 10 wherein said means for changeover occurs when a preselected certain conditional event related to the item being scanned is detected.

12. A method for scanning items on intelligence-bearing documents and forming an electrical representation of a horizontal projection of the item defining a shadowlike effect comprising the steps of scanning the area of the item to be read along a plurality of successive scanning frames and generating a current scan signal characteristic of the item scanned, continuously performing over all scanning frames prior to and including the current scanning frame at least one logical operation on the current scan signal with intercepted portions of the item from all scanning frames prior to the current scanning frame thereby forming a composite transformed scan signal comprising at least one signal element made up of no more than a single bit per element, said composite transformed signal being a logical function of the whole sets of scan signals from all of the scanning frames prior to and including each current scanning frame, storing the composite transformed scan signal, withdrawing the composite signal from storage during successive scanning frame intervals to represent said intercepted portions of the item from prior scanning frames, processing at least one of said composite transformed signals to detect preselected intracharacter patterns where said one composite signal is sometimes utilized before that scanning frame which last intersects the item being scanned, and utilizing the said patterns in preselected combinations for recognizing the item to be identified.

13. The method recited in claim 12 including:

inhibiting the logical operation step when certain conditional events related to the item being scanned are detected, and then changing the logical operation performed on the current scan signal and the intercepted portions of the item from prior scanning frames to form the composite transformed scan signal made up of no more than a single bit per element.

14. Character recognition apparatus comprising a line scanner for generating current scan signals when scanning an item, delay means fed by a composite transformed signal comprising a current scan line signal output of the scanner and a second scan signal representing all scan line outputs prior to the current scanning line of the scanner, means defining a mode of operation continuous over all scanning lines including and prior to the current scanning line for logically operating on each said current scan line signal and second scan signal to continuously produce said composite transformed signal comprising at least one signal element having no more than a single bit per element and being a logical function of the signal elements of the current and second scan signals such that the transformed composite signal corresponds to shadowlike projections of the item, which projections define a configuration Which is related to but distinguishable from the area of the item which is projected, interpreter means responsive to at least one said composite transformed signal and at least one said composite transformed signal and at least one current scan signal generated from the line scanner to detect preselected intracharacter patterns present within the item, at least some of which correspond to said configuration, said one composite signal is sometimes utilized before that scanning frame which last intersects the item being scanned, and translator means responsive to said interpreter means for recognizing the item to be identified in accordance with combinations of said patterns and providing an output signal indicative of the item recognized.

15. The combination recited in claim 14 including means effecting changeover to a further mode of operation continuous over plural scanning lines, and means responsive to said changeover means for performing another logical operation on the second scan signal output and the current scan signal output to form the composite transformed signal during said further mode of operation.

16. Character recognition apparatus comprising

17. Character recognition apparatus as in claim 16 where the said logical operation performed by said logic means is that of addition.

18. Character recognition apparatus as in claim 16 where the said logical operation performed by said logic means is that of subtraction.

19. Character recognition apparatus as in claim 16 where the said predetermined period of time that said delay means delays said transformed scan signal set is slightly less than the period of time required for one scanning frame.

20. Character recognition apparatus as in claim 16 including means responsive to the occurrence for a predetermined number of times of at least said element of said transformed scan signal set for changing the said logical operation performed by said logic means.

21. Character recognition apparatus as in claim 20 where said logical operation is changed from addition to subtraction.

22. Character recognition apparatus as in claim 16 where said decision means is also responsive to said current scanning frame signal to identify said character.

23. Character recognition apparatus as in claim 22 where said decision means includes means responsive to predetermined combinations of said element of said transformed scan signal set and said element of said current scanning frame Signal to provide identification information about said character.

24. Character recognition apparatus as in claim 23 where the projection of the character portion corresponding to said element of said transformed scan signal set and the character portion corresponding to said elements of said current scanning frame signal are vertically disposed with respect to one another within the character.