Abstract: A method of printing on a substrate and a printer are provided. The method uses a printer comprising a print head and a mask having a hole therethrough, the mask being disposed between the print head and the substrate, and comprises aligning the hole with the print head; printing on the substrate through the hole; and misaligning the hole with the print head so that the print head is covered by the mask. The method may allow the servicing of a print head in the array while the printer is printing on the substrate using at least one of the remainder of the print heads in the array.

Abstract: Printing is performed at a full resolution using a first set of nozzles and a second set of nozzles arranged on a printhead. Printing is performed at less than the full resolution using the first set of nozzles less any nozzles in the first set of nozzles that have been determined to be defective. T he second set of nozzles is not used for printing at less than the full resolution except for a subset of nozzles in the second set of nozzles that are used to replace nozzles from the first set of nozzles that have been determined to be defective.

Abstract: A method for automatic pen alignment in a printing apparatus, wherein the printing apparatus has a scan direction or x-axis and a media advance direction or y-axis, orthogonal to said scan direction or x-axis, the method comprising the steps of performing a pen alignment process, determining an alignment correction algorithm to be applied during subsequent printing, to compensate for the misalignment determined in said pen alignment process, measuring an output angle of the media, defined as the angle between the y-axis and the actual direction of advance of the media, with at least one optical sensor arranged stationary on the printing apparatus, and employing the measured output angle to modify the alignment correction algorithm to be applied during subsequent printing.

Abstract: A serial bus system for data communication between devices according to a master-slave protocol has a data bus connecting master and slave devices and a shared clock system arranged to provide a shared-clock signal to the master and slave devices. The master and slave devices are arranged to derive device-individual clock signals which are synchronized with data received on the data bus, from the shared-clock signal and a data-timing indication on the data bus.

Abstract: A hard copy device having a carriage arranged to support a printhead and to reciprocate across a scan axis, the device being arranged to determine the position of at least a part of the printhead along the scan axis, compensating for carriage rotation about the an axis orthogonal to the scan axis, by interpolating or extrapolating from carriage position information derived from first and second codestrips traversing the scan axis and spaced apart in a direction orthogonal to the scan axis.

Abstract: A hard copy device having a carriage arranged to support a printhead and to reciprocate across a scan axis, the device being arranged to determine the position of at least a part of the printhead along the scan axis, compensating for carriage rotation about the an axis orthogonal to the scan axis, by interpolating or extrapolating from carriage position information derived from first and second codestrips traversing the scan axis and spaced apart in a direction orthogonal to the scan axis.