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:
Sep. 24, 2002
Filed:
Mar. 07, 2001
Cheng-Lun Chen, Lafayette, IN (US);
George Tsu-Chih Chiu, West Lafayette, IN (US);
Other;
Abstract
Systems and methods for reducing banding artifact in electrophotographic devices are provided. One such electrophotographic device uses a closed loop controller that receives a feedback signal from an encoder connected to the OPC drum to improve the rotational velocity control of the drum. The encoder provides the rotational position or angular velocity of the drum to the closed loop controller as the feedback signal. Optionally, the electrophotographic device uses a closed loop controller that incorporates a model of the human visual system, such as the human contrast sensitivity function, to help reduce noticeable banding artifacts. The human contrast sensitivity function incorporated into the primary control loop helps filter out low frequency and non-periodic drum rotational velocity fluctuations in producing banding artifacts. The electrophotographic device may also include a repetitive controller in a secondary control loop to help reduce the effect of periodic drum rotational velocity fluctuations in producing banding artifacts. Methods and other systems also are provided.