Dither-synchronized image scanning

摘要

An optical scanning device performs sequential scanning passes. Individual pixels are scanned in response to a clock whose frequency is dithered in repeatable cycles to reduce electro-magnetic interference, and scanning passes are coordinated with the repeatable cycles.

主权项

1. A method of reducing electromagnetic emissions in an image scanner, the method comprising:
in repeated dithering cycles, dithering a frequency of a clock signal that is used for pixel scanning, wherein the pixel scanning comprises scanning pixels of a source image during a scanning pass; coordinating initiation of scanning passes with the dithering cycles such that the beginning of each scanning pass occurs at a same point within a corresponding dithering cycle; performing one or more calibration passes to gather sensor correction data; coordinating the one or more calibration passes with the dithering cycles such that the beginning of each of the one or more calibration passes occurs at the same point within a corresponding dithering cycle; and based on the sensor correction data gathered during the one or more calibration passes, correcting pixel values generated during one or more scanning passes.