Ricoh B230 Training Program page 201

Width detection: Same as for normal mode
Length detection: Done for each sheet
To detect length, the machine counts transport
motor pulses from 'registration-sensor-on" until
"registration-sensor-off"
This explains what occurs if the user selects mixed original-length mode.
Normally, in mixed original-length mode, original length is detected as shown
below:
The width is detected with the same procedure that is used when all
originals are the same size.
The machine keeps an area in memory that is sufficient for an original of
the detected width and 432 mm length.
Printing is done after length detection, and only the part of the memory that
contains data up to the detected original length is printed.
But, if some functions are selected (for example, Auto Reduce/Enlarge), the
length must be detected before image scanning starts. Because of this, the
machine must measure the length before scanning.
It must also make sure that the originals are in the correct sequence before
scanning. Because of this, the three steps in the manual are done.
If the original is duplex, the original is inverted once again after scanning
the first side. Then the second side is scanned, and the paper is fed out.
Why must the machine measure length first when we use Auto Reduce/Enlarge,
Centering, and other functions?
With these functions, the machine must know the length of the original
accurately.
For example, with centering, the image is centered on the copy paper. This
cannot be done if the machine does not know the length of the original
accurately.
Also, with Auto Reduce/Enlarge, the size of the original's image is
decreased to fit on the copy paper. This cannot be done if the machine
does not know the length of the original accurately.
For a full list of applicable functions, please see page 9 of the B386 service
manual.
Mixed Original-Length Mode
•
As a result, scanning is slower if the user selects mixed size
mode
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