Patent ID: 7237872

Claim:
A high-resolution ink jet printer comprising: a drum supported for rotation about an axis and having an outer surface, substrate positioning means for positioning a substrate sheet on the outer surface of the drum to receive a printed image, drum rotating means for rotating the drum, carriage means movable parallel to the drum axis, drop-on-demand printhead means supported on the carriage means and having at least one array of orifices located in spaced relation to the outer surface of the drum for projecting ink drops onto a substrate sheet carried by the drum, actuator means in the printhead means for selectively ejecting individual ink drops from each of the orifices in the array in response to the selective ink drop ejection actuation signals, drive means for driving the carriage parallel to the axis of the drum simultaneously with rotation of the drum and at a rate related to the rate of rotation of the drum, encoder means providing a train of signals at a rate dependent upon the rate of rotation of the drum, and control means for supplying ink drop ejection actuation signals to the printhead means for controlling the selective ejection of the ink drops from each of the orifices in the array, in which the ink drop ejection actuation signals are timed to selectively eject ink drops from each orifice for deposition at predetermined locations on the substrate sheet.