Toshiba e-STUDIO4500c Service Manual page 749

August, 2006
Detection Timing
When the power is on, the APS sensors are always active, but the CPU checks
their signals only after the platen is lowered.
Book Mode
In the Book mode (when the ARDF is open), the CPU checks the APS sensors and
determines the original size after [Start] is pressed.
ARDF Mode
The CPU checks the APS sensors after the platen is lowered.
Bypass Mode
The APS sensors are ignored when copy paper is fed from the bypass tray, but the
bypass tray can handle a variety of sizes and orientations. To accomplish this:
The machine always assumes short-edge feed for paper on the bypass tray.
Width is measured by a sensor inside the bypass tray.
The bypass tray cannot measure length, so the registration sensor determines
the length of the paper using clock pulses.
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SCANNER UNIT