A microprocessor based mark-sense ballot card reading system has automatic mark detection threshold adjustment, automatic skew and card speed correction, and provision for simultaneous, accurate reading of both sides of a ballot card regardless of card input orientation. A multidispatch, miltipage real...http://www.google.com.tw/patents/US4479194?utm_source=gb-gplus-share專利 US4479194 - System and method for reading marks on a document
