PURPOSE: To always obtain the necessary information assuredly as well as to increase the reading accuracy by shifting the position of the scanning line by the disance shorter than the pitch of the scanning line and with every scanning.
CONSTITUTION: The character identical to (A) in the figure is shifted by the distance shorter than the pitch of the scanning line from positions of scanning (1), (2), (3) and (4) in the 2nd scanning. And, for instance, the scanning is given (A)' at just 1/2-pitch shifted positions (1)', (2)', (3)' and (4)'. The signals thus obtained are like (B)' and (C)', and stain N is erased in the scanning of (2)'. Thus, the segment emerges at the right upper shoulder of the character. Accordingly, the character which could not be read out with the 1st scanning (1)W(4) can be read out correctly with the 2nd scanning (1)'W(4)'.