Printing apparatus and method of operation of a printing apparatus

A printing apparatus including a print roller for guiding a substrate to be printed, a printhead for transferring ink from a ribbon to the substrate by bringing the ribbon into contact with the substrate at a contact point on the print roller and a top dead centre locating mechanism to locate a top dead centre position of the print roller, wherein the top dead centre position of the print roller is a position on the circumference of the print roller defined as the position at which the contact point is the shortest distance of travel of the printhead relative to the print roller, from a retracted, non-printing position to an extended printing position in a direction which is substantially transverse to a direction of travel of the substrate.

A method of locating a top dead centre position of a print roller of a printing apparatus, the printing apparatus further including a printhead including at least one printing element, the printhead being operable to transfer ink from an inked ribbon to a substrate to be printed by bringing the ribbon into contact with the substrate at a contact point on the print roller, the method including moving at least a part of the printhead in a lateral direction relative to the print roller, such that the printhead traverses the print roller in a first direction, and moving the printhead in a direction which is substantially transverse to the first direction, between a first position and a second position in which a part of the printhead contacts the print roller, the method further including determining the lateral position of the printhead relative to the print roller at which the distance between the first position and the second position is a minimum.

A method of adjusting the effective length of a printing element of a printing apparatus, the printing apparatus being of the kind including a print roller for guiding a substrate to be printed, a printhead including at least one printing element, the printhead being operable to transfer ink from an inked ribbon to the substrate by bringing the ribbon into contact with the substrate at a contact point on the print roller, wherein a printhead angle is subtended between a part of the printhead which transfers ink from the ribbon to the substrate and a radius of the print roller at the contact point wherein the method includes adjusting the printhead angle in accordance with the speed of the ribbon relative to the printing apparatus.