Patent ID: 7845632

Claim:
A media feeding apparatus for a printing system, comprising: a tray supporting media to be fed into the printing system; first and second media guides operatively coupled to the tray for engaging opposite sides of the media to position the media on the tray, the first media guide being movable relative to the tray along an axis; a potentiometer with a base mounted in a fixed position relative to the tray and a slidable member operatively coupled to the first media guide to move relative to the base when the first media guide is moved relative to the tray, the potentiometer providing an electrical output signal indicative of the relative position of the first media guide and the tray; an opto-interrupt sensor mounted in a fixed position relative to the tray and having an optical signal source providing an optical signal along an optical signal path and an optical signal detector spaced from the optical signal source by an optical sensing gap, the opto-interrupt sensor providing an electrical output signal indicative of the presence or absence of an optical obstruction in the gap; an optical obstruction structure operatively coupled to the first media guide to move relative to the opto-interrupt sensor when the first media guide is moved relative to the tray, the optical obstruction structure including at least a first fin movable within the optical sensing gap to block the optical signal path for a first portion of the movement range of the first media guide and to allow receipt of the optical signal by the optical signal detector for a second portion of the movement range of the first media guide; a ramp structure mounted in a fixed position relative to the first media guide and having an edge for engaging the slidable member of the potentiometer, the ramp structure edge having a profile at an angle to the axis to move the slidable member of the potentiometer relative to the base when the first media guide is moved relative to the tray; and a biasing structure to bias the slidable member against the edge of the ramp structure as the first media guide is moved relative to the tray.