Kristina J Wood

US Patent:

62123548, Apr 3, 2001

Filed:

Dec 15, 1999

Appl. No.:

9/464219

Inventors:

Judith A. Garzolini - Boise ID
Kristina J. Wood - Eagle ID
Kenneth E. Heath - Boise ID
Joseph C. Carls - Austin TX
Dennis D. Anderson - Leander TX

Assignee:

Hewlett-Packard Company - Palo Alto CA
3M Innovative Properties Company - St. Paul MN

International Classification:

G03G 1520

US Classification:

399324

Abstract:

Hot offset of black toner is reduced or eliminated in a color electrophotographic imaging device, such as a laser printer, by applying a minimal layer of non-black toner in addition to the black toner on a print media. The non-black toner, such as cyan, magenta or yellow toner, acts as a release agent for reducing or eliminating hot offset of the black toner during fusing of the toner to the media. The non-black toner is applied as a thin layer just sufficient to reduce hot offset of the black toner and such that an appearance of a resultant image formed retains a visual perception of being a black toner only image. In an alternate embodiment, the thin layer of non-black toner is applied in response to coated media being processed, such as overhead transparencies, that are more susceptible to hot offset. In yet a further alternate embodiment, raster source image data is converted to output data using a process neutral axis color rendering table, and vector source image data is converted to output data using the same process neutral axis color rendering table only if coated media is being processed, thereby reducing hot offset of black toner. Otherwise, the vector source image data is converted to output data using a black only neutral axis color rendering table.

US Patent:

62195190, Apr 17, 2001

Filed:

Oct 24, 2000

Appl. No.:

9/695818

Inventors:

Judith A. Garzolini - Boise ID
Kristina J. Wood - Eagle ID
Kenneth E. Heath - Boise ID
Joseph C. Carls - Austin TX
Dennis D. Anderson - Leander TX

Assignee:

Hewlett-Packard Company - Palo Alto CA
3M Innovative Properties Company - St. Paul MN

International Classification:

G03G 1501
G03G 1520

US Classification:

399321

Abstract:

Hot offset of black toner is reduced or eliminated in a color electrophotographic imaging device, such as a laser printer, by applying a minimal layer of non-black toner in addition to the black toner on a print media. The non-black toner, such as cyan, magenta or yellow toner, acts as a release agent for reducing or eliminating hot offset of the black toner during fusing of the toner to the media. The non-black toner is applied as a thin layer just sufficient to reduce hot offset of the black toner and such that an appearance of a resultant image formed retains a visual perception of being a black toner only image. In an alternate embodiment, the thin layer of non-black toner is applied in response to coated media being processed, such as overhead transparencies, that are more susceptible to hot offset. In yet a further alternate embodiment, raster source image data is converted to output data using a process neutral axis color rendering table, and vector source image data is converted to output data using the same process neutral axis color rendering table only if coated media is being processed, thereby reducing hot offset of black toner. Otherwise, the vector source image data is converted to output data using a black only neutral axis color rendering table.