Patent Issued for Linear Light Diffusing Structure for Document Scanners

By a News Reporter-Staff News Editor at Journal of Engineering -- Lexmark International, Inc. (Lexington, KY) has been issued patent number 8322872, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Cui, Chengwu (Lexington, KY); Jackson, David Keith (Lexington, KY); Strow, Joshua Tyler (Lexington, KY).

This patent was filed on October 13, 2009 and was cleared and issued on December 4, 2012.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates generally to image forming devices, and particularly to scanners and scanning methods. More specifically, the present invention discloses a linear light diffusing structure to form a substantially uniform light output beam for illuminating a media sheet when placed on an imaging surface.

"Scanners are used to scan an image from a sheet of media and create scanned image data which can be displayed on a computer monitor, printed, sent via facsimile transmission, etc. Scanned image data may be saved in memory or a magnetic or optical drive, or other memory device. Scanning devices may be packaged in a stand-alone housing or as a part of a multi-functional product, including a product having a printing component, to perform scanning as well as standard copying functions.

"In a conventional scanner, the desire to use light emitting diodes (LEDs) as a light source for scanner is not new. LEDs are mercury free, instant-on and compact. However there are a few factors that hinder the use of LEDs in a high speed document scanner. The top hindering factors are cost and output intensity. With the rapid advancement in research, development and manufacturing of LEDs, cost and output performance are reaching acceptable levels and therefore there is the renewed interest in using high powered LEDs as the illumination source for high speed documents scanners. In addition to cost and output level, there are additional factors that often need to be carefully controlled. One is thermal stability. The inherent nature of a small LED chip outputting a high intensity light presents challenges to dissipate heat efficiently so that the LED is not thermally affected both in output intensity and spectral composition to negatively impact scan image quality. Another factor is the non-uniformity of the light profile when a limited number of LEDs are used to save cost. Since the LED's light emitting PN junction is usually small, the light output profile can be highly irregular and difficult to control even with elaborate lens designs which disadvantageously increases cost.

"Given the foregoing, it would be desirable therefore to provide a substantially thermally stable, light generating structure which provides a substantially uniform light output for a scanning device."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Embodiments of the present invention overcome shortcomings of prior lighting devices and thereby satisfy a significant need for a thermally stable lighting device that generates a substantially uniform light profile. According to an exemplary embodiment of the present invention, there is provided an image forming device that includes an imaging surface for supporting a media sheet; a substantially tubular structure having an opening defined thereon, the tubular structure being disposed in proximity to the imaging surface; and a plurality of light sources mounted on an inner surface of the tubular structure for illuminating the media sheet when placed on the imaging surface such that light emitted from the plurality of light sources is reflected from the inner surface before exiting the tubular structure through the opening as diffused light. The diffused light generated is reflected off the media sheet and captured by a sensing unit for use in generating an image of the media sheet.

"In some embodiments, the cross section of the tubular structure is substantially circular in shape.

"In another embodiment, the opening of the tubular structure has a width of about 40% of the inner diameter of the tubular structure.

"In yet another embodiment, the tubular structure includes plurality of heat dissipating fins extending from an outer surface of the tubular structure.

"In yet another aspect of the invention, a tubular structure is disclosed that includes an opening defined therein, a plurality of light sources mounted on an inner surface, the tubular structure having a density of light sources at end portions that is greater than the light source density at other portions of the tubular structure.

"In another embodiment, the tubular structure is made up of a thermally conductive material."

For the URL and additional information on this patent, see: Cui, Chengwu; Jackson, David Keith; Strow, Joshua Tyler. Linear Light Diffusing Structure for Document Scanners. U.S. Patent Number 8322872, filed October 13, 2009, and issued December 4, 2012. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=100&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4995&f=G&l=50&co1=AND&d=PTXT&s1=20121204.PD.&OS=ISD/20121204&RS=ISD/20121204

Keywords for this news article include: Lexmark International Inc.

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