Patent ID: 8270024

Claim:
An apparatus for printing within a predefined print zone on a selected surface of a skewed object while the object is moving in a given direction of travel, said apparatus comprising: a bracket positioned adjacent to the object and the given direction of travel thereof; at least two sensors mounted on said bracket in known positions spaced apart from each other, disposed adjacent to the direction of travel of the object, and oriented toward a given surface of the object as the object moves past said sensors, each of said sensors operable to generate an electrical signal containing a known change in a property of said signal coincident with detection of a leading edge of the given surface of the object by said sensor; a positioning mechanism mounted on said bracket downstream of said sensors relative to the direction of travel of the object and adjacent to the selected surface of the object as the object moves past said positioning mechanism; a printhead mounted on said positioning mechanism for undergoing positioning relative to the selected surface of the object, said printhead being operable to print on the selected surface of the object as the object moves past said printhead, said positioning mechanism being operable to position said printhead into a known correct printing orientation relative to the selected surface of the object; and a controller provided in communication with each of said sensors, said positioning mechanism and said printhead and storing a skew calculation algorithm, said controller being operable to receive said signal from each of said sensors and in response thereto to initiate said skew calculation algorithm to make a calculation of skew of the object and thus of the predefined print zone on the selected surface of the object, and to operate said positioning mechanism to position said printhead into the known correct printing orientation and to operate said printhead to print within the predefined print zone on the selected surface of the object in response to the skew calculation so as to compensate for the skew of the object as the object moved past said printhead.