Patent ID: 7156483

Claim:
A method for determining the ink drop velocity of a carrier-mounted printhead disposed at a gap above a print medium comprising the steps of: a) printing a first ink mark on the print medium using the printhead with the printhead carrier moving along a printhead-carrier-scanning axis at a first printhead velocity, wherein the printhead begins ejecting ink corresponding to the first ink mark at an ink-ejection position along the printhead-carrier-scanning axis; b) printing a second ink mark on the print medium using the printhead with the printhead carrier moving along the printhead-carrier-scanning axis at a second printhead velocity which is different from the first printhead velocity, wherein the printhead begins ejecting ink corresponding to the second ink mark at the ink-ejection position plus an offset distance, and wherein the second ink mark is spaced apart from the first ink mark; c) generating an optical scan of at least a portion of the print medium using a non-printhead-carrier-mounted optical scanner; d) measuring the distance between the first and second ink marks using the optical scan; and e) calculating the ink drop velocity using the measured distance, the offset distance, the first and second printhead velocities, and the gap.