| 摘要 |
PURPOSE:To detect the size of an original, by scanning the original in the direction reverse to the exposure scanning direction using a photosensor functioning in the invisible region in order to detect the edge of the original. CONSTITUTION:An optical system is moved in direction arrow 1 to scan the original. At the same time, photosensor 4 is moved in direction arrow 2 to scan the original by emitting infrared rays toward original platen glass 1 and receiving the reflected rays. FF5 is set by a count start signal, its output actuates amplifier 6 and delivers to reset input terminal R. Fundamental clock passes through AND circuit 7 and is counted by the output of FF5 in counter 8. Photosensor 4 scans original pressing cover 3 and original 2 in the direction reverse to that of original scanning, and the contents of counter 8 indicate the position of left side edge of original 2, i.e. the size of original 2. |
