Compensating for periodic nonuniformity in electrophotographic printer

A method of compensating for periodic nonuniformity in an electrophotographic (EP) printer, comprising:

• providing the EP printer with a rotatable imaging component, and with a runout sensor for measuring the distance between a reference point and the surface of the rotatable imaging component along a reference axis;
• a first rotating step of rotating the rotatable imaging component and, while the rotatable imaging component is rotating, measuring the respective distances at a plurality of angles of rotation of the imaging component using the runout sensor;
• as respective first distances;
• determining respective correction values corresponding to one or more of the measured first distances, and storing the correction values and corresponding angles of rotation in a memory, or storing the measured distances in the memory;
• receiving an image signal representing a print image to be deposited on a receiver by the printer;
• a second rotating step of rotating the rotatable imaging component and, while the rotatable imaging component is rotating:
• determining an angle of rotation of the imaging component;
• retrieving from the memory one or more determined correction value(s) corresponding to the determined angle of rotation using the processor, or retrieving from the memory the stored distance(s) corresponding to the determined angle of rotation and determining one or more corresponding correction value(s);
• automatically adjusting the image data corresponding to the determined angle of rotation with the correction value(s) using the processor;
• and
• depositing toner corresponding to the adjusted image data on the receiver using the rotatable imaging component.

A method of compensating for periodic nonuniformity in an electrophotographic (EP) printer, comprising:

• providing the EP printer with first and second rotatable imaging components arranged to cooperate in producing the image on the receiving member, and with first and second runout sensors corresponding to the respective imaging components for measuring respective distances between respective reference points and the surfaces of the respective rotatable imaging components along respective reference axes;
• a first rotating step of rotating the first and second rotatable imaging components and, while the rotatable imaging components are rotating, measuring the respective distances at first and second pluralities of angles of rotation of the imaging components using the runout sensors as respective first distances of the first component and second distances of the second component;
• determining respective correction values corresponding to one or more of the measured first distances and second distances, and storing the correction values and corresponding angles of rotation of the first and second components in a memory, or storing the measured first and second distances into the memory;
• receiving an image signal representing a print image to be deposited on a receiver by the printer;
• a second rotating step of rotating the first and second rotatable imaging components and, while the components are rotating:
• determining first and second angles of rotation of the respective imaging components using an encoder or a timer;
• retrieving from the memory one or more determined correction value(s) corresponding to the determined angles of rotation of the first and second components, or retrieving from the memory one or more stored distance(s) corresponding to the determined angles of rotation and determining one or more corresponding correction value(s);
• automatically adjusting the image data corresponding to the determined angles of rotation of the components with the correction value(s) using the processor;
• and
• depositing toner corresponding to the adjusted image data on the receiver using the rotatable imaging components.