Detecting the Size of Originals.
The machine identifies the size of an original with reference to the combination of measurements taken of the light reflected at specific points of the CCD and the
output of a reflection type sensor.
It takes measurements at 2 points for individual sizes to ensure correct identification even in the event that the original is displaced
while the ADF is being closed.
- for main scanning direction, by the CCD (for AB, 8 points; for inch-configuration, 6 points)
- for sub scanning direction, by a reflection type photosensor (for AB-configuration, 1 point; for inch-configuration, 1 point)
The machine identifies the size of an original as follows:
1) External Light (main scanning direction only)
While keeping the scanning lamp off, the machine measures the CCD level at individual points of measurement in main scanning direction.
2) Sensor Output Level
The machine turns on the scanning lamp, and measures the CCD level at individual points of measurement in main scanning direction. Also, the machine turns
on the LED of the reflection type photosensor in sub scanning direction to measure the sensor output.
It uses the combination of the measurement and the output
to identify the size of the original in question.