Facsimile and static presentation processing – Natural color facsimile – Scanning
Reexamination Certificate
1998-07-31
2001-04-17
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Natural color facsimile
Scanning
C358S505000, C358S474000, C358S475000, C358S486000, C358S488000, C355S075000, C399S380000, C399S379000
Reexamination Certificate
active
06219158
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to scanners, copiers, facsimile machines and other devices used for transforming an optical image of a document into a electronic signal and more specifically to a reflective surface used behind a document to be imaged.
BACKGROUND OF THE INVENTION
Electronic document scanners, copiers, and facsimile machines transform an optical image of a document into an electric signal suitable for storing, displaying, printing or electronic transmission. Documents to be scanned may generally be classified as either transparent or opaque. For opaque documents, light is reflected off an image on the surface of the document onto a photosensitive transducer, typically a photoconductive drum or an array of photosensitive sensor elements. However, documents are rarely completely opaque. In a typical device, some light passes through the document to a secondary reflective surface, for example a lid or automatic document feeder. Some light then reflects off the secondary reflective surface and passes back through the document a second time. The light that passes through the document twice may also be detected by the photosensitive transducer. If the document has an image on both sides, the image adjacent to the secondary reflective surface may be partially imaged onto the photosensitive transducer. For example, when copying double sided documents, sometimes an image on the back of the document partially appears in the resulting copy. This undesirable result is often called “bleed-through.” There is a need for reduction of bleed-through in copiers, scanners, facsimile machines and similar devices.
SUMMARY OF THE INVENTION
An improved document lid and secondary reflective surface is provided that minimizes bleed-through and affects other image parameters of interest, such as brightness, contrast and color shift. The document lid and secondary reflective surface, which is the scanning or copying background is dynamically variable and controlled to be either all white, all black, grey or some other color. The scanning or copying background can also be varied in different regions, such that different regions can simultaneously be white, black, grey or some other color. The scanning or copying background may be directly controlled by the user or by a preview scan and software or firmware that adjusts the background to minimize the effects of bleed-through during the scanning/copying process.
REFERENCES:
patent: 4623938 (1986-11-01), Asano et al.
patent: 4671642 (1987-06-01), Ohkubo et al.
patent: 5278674 (1994-01-01), Webb et al.
patent: 5790211 (1998-08-01), Seachman et al.
Hewlett--Packard Company
Lee Cheukfan
Mitchell Cynthia S.
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