Sharp AR-280 Service Manual page 187

12) Second page preliminary paper feed end
13) Second page paper feed start (Front)
14) Second page paper feed end (Front)
15) Second page reverse start
16) Second page reverse end
17) Second page paper feed start (Back)
18) Second page paper feed end (Back)
19) Second page paper exit start
20) Second page paper exit end
B. Document size detection method
This machine detects document sizes in the following three ways.
1) Document size detection by the document set tray
When documents are set in the document set tray, the size is de-
tected to enable the automatic selection of the suitable paper and the
copy magnification ratio according to the detected size.
When mixed sizes of documents are set, the max. size is detected.
The document width is detected by TRVR (size volume), and the
document length by TRS-S and TRS-L (tray sensors) to identify the
document size.
The judgement of a document size is made at the timing when the
empty sensor (EMPS) detects a document.
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