PRINTING LINE DETECTION DEVICE OF PASSBOOK AND THE LIKE

摘要

PURPOSE:To enable an erroneous judgement of printing lines due to the adverse effect of dust or fouling to be eliminated by dividing a detection area in each scan by an image sensor to a line longitudinal direction and judging the condition of a printing line from an overall availability status of printing detection signals from each divided area. CONSTITUTION:A detection area L of a passbook 1 is divided into two subareas such as first subarea L1 and second subarea L2. A counter PTM2 compares printing detection signals in the first subarea L1 and the second subarea L2 among clock inputs CLK with subdivision pulses interposed which are input through an 'OR' gate OR2, with a set value. If an image sensor scans a fouled part 2 in an unprinted area, the counter PTM2 outputs 'OUT' output corresponding to only the first subarea L1 to a flipflop FF1, because the printing detection signal increases beyond a set value in the first subarea L1 and conversely decreases in the second subarea L2. Consequently an output A of an 'AND' gate AND3 is maintained to 'L' level, thus preventing against fouling and allowing a 'No Printing' judgement to be made correctly.