Ricoh IS450S Service Manual page 26

SCANNER MECHANISMS 22 December 1998
Optional Steps
Size Detection
[A]
[B]
[C]
[D]
G411D523.WMF
If selected, this is done after document table lift/paper feed.
1) Main Scan Direction (Document Width)
This function will be available when the optional IPU board is installed.
First of all, the original is fed to the scan ready position between the read sensor
[B] and the size detection position [C]. Then the first scanner moves to the size
detection position [C] from the ADF scanning position [D]. After that, the original is
fed to the ADF scanning position.
As a result of the above operation, the original is fed 5 mm past the first scanner.
Then the CPU detects the original width. The edge of the document is detected by
the difference between the level of the document data and the background level,
which is provided by the black bracket located over the ADF exposure cover.
If there is a gap at the leading edge, such as a tear (or a black stripe), extending
more than 1 mm across the paper and more than 5 mm down the paper, the
machine cannot detect the document width past this gap. In this case, an error
message may appear, and scanning is impossible. Disable this feature to allow the
machine to scan this document.
After finishing the above operation, the first scanner returns to the ADF scanning
position.
2) Sub Scan Direction (Document Length)
The length of the original is calculated by counting the motor pulses while the feed
sensor [A] is on. (The length is detected during scanning.)
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