US Patent 7261480 Print shaft contamination detector

A system and method for providing a self-diagnostic process for determining a print shaft contamination condition such as debris build up on the guide shaft in a shuttle head printer is described. The process can be carried out at several points in time including automatically when the printer is powered-up, at a periodic schedule, and/or at the initiation of a user. The process includes a measurement of the print head speed over a travel distance along the guide shaft. If the speed is lower than a predetermined threshold value, the user is notified that a print shaft contamination condition exists.