When an original is placed on the original tray, the light-blocking plate operates in keeping with the detecting lever of the LGL sensor to block the light of the

photo interrupter. The machine identifies whether or not the original is LGL with reference to the LGL sensor signal (LG_S) and the width of the original. The

machine communicates the original size information to the host machine as soon as the Start key is pressed.

b. Detecting the Size of the Original in Width Direction.

The width of an original is detected using the original width detecting volume (VR1) found inside the original tray. The volume operates in conjunction with the

slide guide, its resistance changing (analog) as the slide is moved. The ADF driver PCB reads these changes in resistance as the original size signal (WIDTH), and

recognizes them as specific widths.

To make sure that the original width volume (VR1) correctly detects A4R/LTRR and A5R/STMT widths, a special AB/inch sensor (PI4) is used inside the original

tray; the sensor goes '1' (AB/inch identification signal) when the width of the original is 197 mm or more and less than 214 mm.

ADF driver PCB

Trailing edge of the original

(small size)

PI8

PI7

Trailing edge of the original

(large size)

F-2-18

ADF driver PCB

Large size original

F-2-19