| 摘要 |
In a document reproduction apparatus with an imaging station and a sheet feeding system for feeding physical document sheets in a sheet feeding path at a first velocity in a document sheet motion direction to the imaging station to be imaged, with a transmissivity sensor for measuring the transmissivity of the document sheets to provide an imaging control signal for reducing show-through imaging defects from light transmissive document sheets including opposite side images of duplex documents, there is provided a document sheet light transmissivity measurement system with a scanning system for linearly moving a single scanner on a single axis at a second velocity across the sheet feeding path orthogonally of the document motion direction in coordination with the document sheet movement at the first velocity so that the scanner diagonally scans the document on two axes before the document is imaged, to provide a more accurate transmissivity measurement of the document sheet than a single axis transmissivity scan, preferably with a ratio of these first and second velocities equal to the ratio of the side and end dimensions of the document being scanned to scan diagonally across the document from one corner to an opposite corner and thereby scan into all four of the possible unprinted edge margins of the document to obtain an imaging control signal therefrom.
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