exit roller unit 16 includes an exit roller 48 and a corresponding exit pinch roller 50 in the embodiment shown index roller 44 and exit roller 48 are driven rollers that are driven by a drive unit 52 pinch rollers 46 and 50 are idler rollers and apply a biasing force to hold the print medium sheet 22 in contact with their respective driven rollers 44 48 drive unit 52 includes a drive source such as a stepper motor and an associated drive mechanism such as a gear train or belt pulley arrangement during operation index roller 44 incrementally advances print medium sheet 22 in a sheet feed direction 54 toward and into a print zone 40 across mid frame 20 as shown in fig1 sheet feed direction 54 is depicted as an x within a circle to indicate that the sheet feed direction is in a direction perpendicular to the plane of fig1 toward the reader sheet feed direction 54 is substantially perpendicular to main scan direction 42 and in turn substantially perpendicular to bi directional scanning path 34 a once print medium sheet 22 is released from the nip formed by index roller 44 and index pinch roller 46 exit roller 48 is controlled to continue the incremental advancement of print medium sheet 22 through print zone 40 and ultimately expels print medium.