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公开(公告)号:US3596063A
公开(公告)日:1971-07-27
申请号:US3596063D
申请日:1969-01-13
Applicant: IBM
Inventor: CURTIS TERRY W , KEILLOR ROBERT D , MEHAFFEY DONALD L
CPC classification number: G06K7/1092
Abstract: An apparatus and method for optically reading marks on a document. A first portion of each mark area is scanned during a first scan and a second portion of each mark area is scanned during a second scan. On the first scan, latches are set for positions where the video output is above a predetermined minimum. During the second scan, a second series of latches are set if the video output is above a predetermined minimum and the corresponding first scan latches are set. An output is provided only when the second latches are set.