The width of an original is identified in terms of the presence or absence of exter-nal light; here, the external light is blocked and the absence of an original

is identified, excluding B5, B4, A4, and A3.

[4] The copyboard cover is closed.

When the copyboard cover is brought down to 25 deg, the Copyboard cover sensor detects the "closed" state, and original size detection starts.

For main scanning direction, the xenon lamp is turned on, and the CCD checks for reflected light (4 points).

For sub scanning direction, the original sensor starts detection.

[5] The copyboard cover is fully closed.

The changes in the output level of each sensor are monitored until the copyboard cover is fully closed. The absence of a change is identified as indicating

the absence of paper, and the size of the original is identified based on the combination of changes in level at five points

[6] The scanner remains in wait (for a press on the Start key).

The No. 1 mirror base moves to home position, and the scanner waits for a press on the Start key (wait state).

5-24

Xenon lamp

Original sensor

Point of original detection 1

Copyboard cover

Point of original detection 2

Point of original detection 3

Point of original detection 4

Reader unit