Patent ID: 8035093

Claim:
A printing system comprising: a movable tray for holding recording media, wherein the movable tray includes reference marks provided at a predetermined spacing for determining a distance traveled by the movable tray; a reference-mark optical detector positioned to provide a field of view through which the reference marks pass as a result of motion of the movable tray; an identifying-mark optical detector positioned to provide a field of view through which media-type identifying marks on a piece of recording medium pass as a result of motion of the movable tray; a signal processor to provide an output relative to: a) the amount of reference marks passing through the field of view of the reference-mark optical detector as the movable tray moves, and b) the signal variation in a signal provided by the identifying-mark optical detector as the movable tray moves; a look-up table including a plurality of media identification signal patterns that are correlated to corresponding media types; and a comparator that compares the output of the signal processor to the plurality of media identification signal patterns in the look-up table in order to identify type of recording medium.