Method of determining optimum time for replacing the media feed roller of a printing device

Abstract

A method for alerting a user when the time has arrived to replace a media feed roller on a printing device, employs statistical analysis of data gathered relating to the number of pages between misfeeds associated with the media feed roller. It has been ascertained that the misfeed rate associated with media feed roller failure follows a characteristic pattern, which may be treated as a step function. That is to say that, beginning with a new media feed roller, the feed failure rate, which is usually measured in pages printed between misfeeds, remains relatively constant. However, as the time for replacement nears, the graph begins to plunge precipitously, as misfeeds begin to occur with increasing regularity. After the plunge, the misfeed rate continues to increase, but at a decreasing rate. Eventually, the feed failure rate reaches a value that represents a misfeed during every page feed. The optimum time for replacement is deemed to be shortly after the graph begins to plunge. However, because there is a certain degree of randomness to the feed failure phenomenon, it is necessary that notification of the need for replacement of the media feed roller be given based on accumulated data sufficient to make a statistically valid directive to the printer user. The preferred method for providing a roller replacement directive to the user is to begin tracking feed failures when a feed failure rate value falls within a predetermined replacement range for the first time. After a statistically significant number of subsequent misfeeds indicate that the misfeed rate average is within the fixed replacement range, the replacement directive may be issued.