Browse Prior Art Database

Optical Mark Sensing of Single Color Documents

IP.com Disclosure Number: IPCOM000087422D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Plummer, WB: AUTHOR

Abstract

Optical mark-reading (OMR) machines conventionally read documents having mark-locating bubbles printed in an ink which is visible to the eye but invisible to the machine. Machine-readable timing marks in a special document area then gate the photosensors to accept marks in the data locations. This requires a two-color printing process which is expensive and requires careful alignments.

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Optical Mark Sensing of Single Color Documents

Optical mark-reading (OMR) machines conventionally read documents having mark-locating bubbles printed in an ink which is visible to the eye but invisible to the machine. Machine-readable timing marks in a special document area then gate the photosensors to accept marks in the data locations. This requires a two-color printing process which is expensive and requires careful alignments.

Document 10, above, carries a series of bubbles 11 which are printed in an ink visible to photosensor array 20. Array 20, comprising a large number of very small photodetectors in a line, passes information through analog/digital converters into a shift register (not shown). The detection of the bubble outlines would cause logic or programming to look for data between these thin outlines. Skew and offset of document 10 relative to array 20 is easily tolerated by such a system, by operating on multiple rows of clocked data.

Although conventional timing marks would not normally be required, marks 12 could be provided to gate the mark-recognition function on and off in the proper areas of complex documents having other graphic material which may be visible to array 20. Even in this case, however, only a single color ink is required for the form; there is no need for an invisible or background color. Also, document tolerances can be looser because of the inherent misalignment correction in the bubble-recognition capability.

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