Ricoh IS450S Service Manual page 20

SCANNER MECHANISMS
Optional Steps (Optional IPU Board)
Size Detection
If selected, this is done after the 'Initialization' step.
1) Main Scan Direction (Document Width)
The first scanner moves to the book mode standard position ([F] on the previous
page). Then, the scanner scans 5 mm from the book mode standard position.
The scanner determines the document width in the main scan direction from the
output signal level. The edge of the document is detected by the difference
between the level of the document data and the background signal which is
provided by the silver plate [G] attached to the platen cover across the main scan.
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.
2) Sub Scan Direction (Document Length)
The scanner detects the document size only in the main scan direction, and the
scanner driver determines that the document length is the same as for a standard
paper size of the same width.
NOTE: The scanner always assumes the paper is in a lengthwise orientation (i.e.,
the main scan is the short side). Also, in USA models, if Letter width is
detected, the paper is always assumed to be Letter size (this means that
the last few inches of a Legal-size original will not be scanned).
Read Size Command
If selected, this is done after the 'Initialization' step.
1) Read Size Command
If the scanner receives the Read Size command in book mode, it detects the size
in the main scan direction as described above.
The scanner sends the width data to the host computer.
After detecting the document size, the scanner scans the detected area.
Abort Command
This can occur at any time during the basic scanning procedure.
If the Abort command is received during scanning, the scanner motor is stopped.
Then the scanner returns to the home position ([D] in the previous diagram).
If this command is received while the scanner is reversing or checking the home
position, the operation is not interrupted.
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22 December 1998