The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 05, 2001
Filed:
Jan. 10, 2000
Robert W. Jewell, Boise, ID (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A fixing device bias control system compensates for variations in media resistivity by controlling a bias supplied to a fixing device, such as a fuser, in an electrophotographic imaging device. Media resistivity may change dependent upon on the environmental conditions to which the media is exposed. A reduction in the moisture content of the media, as occurs after the first pass of a duplex imaging operation or in low humidity environments, will significantly increase the media resistivity. An increase in the resistivity of the media can result in toner adhering to the fuser, causing contamination on the fuser and image defects. The fixing device bias control system supplies a bias, having the same polarity as the charge on the toner, to a fusing roller included in the fuser to repel the toner, thereby reducing fuser contamination and image defects. In a first embodiment, the fixing device bias control system controls the bias based upon exposure of the media to the fixing process. The corresponding method includes controlling the bias to the fixing device according to whether the media has been previously exposed to the fixing process. In a second embodiment, the fixing device bias control system controls the bias based upon either a voltage or a current supplied to a transfer device. The corresponding method includes controlling the bias to the fixing device according to the voltage or current supplied to the transfer device.