| 摘要 |
<p>A scanner for scanning a document (10) positioned against a backing surface (14) to determine the position of the document includes photoelectric transducers (24, 26, 28) which provide electrical scan signals in dependence upon the light reflected from the document and from the backing surface at a plurality of moving scan positions (44) as the scan positions move across both the document and the backing surface. A recognizable background image (42) is defined on the document backing surface such that the photoelectric transducers (24,26,28) provide a recognizable pattern of scan signals as the document backing surface is scanned, thereby indicating the position of the document. The recognizable background pattern may include a plurality of stripes (42) which extend substantially perpendicular to the direction of movement of the scan positions. Alternate ones of the stripes may be black with intermediate ones of the stripes being white.</p> |
