Abstract: A method includes providing a printhead for printing an image on a surface from two different printhead positions relative to the surface, the two different printhead positions at first and second orientations, wherein the at least one printhead and the surface move relative to each other along a print path having two potentially overlapping swathes, determining an overlap area on the surface for the two overlapping swathes wherein the overlap area is to be printed on from either of the two different printhead positions, determining for each position in the overlap area at which an inkjet drop may be printed the angle of incidence at the surface of that drop, and selecting a stitch point or region in the overlap area wherein the difference between the angles of incidence at the surface of drops from the two printhead positions is kept within an acceptable limit.

Abstract: A method of controlling a system including an arrangement of at least two nozzles, wherein the arrangement and the shape move relative to each other, each nozzle traces a respective path on the shape, and each nozzle is configured to jet drops at actual jetting locations along the respective path of the nozzle. The method results in sequence of actuation events received from a control signal to be more frequent than would be needed for an arrangement printing on a flat surface to produce the required dot resolution. It is then possible to select which of the individual nozzles are to jet for a given actuation event from the sequence so that the actual jetting locations deviate from the target jetting locations by no ore than a define maximum error distance.

Abstract: A method of controlling a system including a printhead for printing an image on at least one surface, wherein the at least one surface differs in shape from a nominal surface by a known tolerance, and wherein the printhead and the at least one surface move relative to each other along a predetermined print path comprising at least one swathe. Small dot patterns (referred to as “pathfinders”) are printed on a surface of the object in a preliminary printing pass, then the printed dot patterns are analyzed, for example with a machine vision system. The necessary corrections may then be calculated from this analysis and applied to a subsequent full printing pass.

Abstract: A printing system for printing images formed of pixels on a substrate, the system comprising a print system arranged where printheads traverse a substrate, the print system arranged to receive a sequence of print actuation requests in order to print each pixel of an image upon the substrate, the print system having an acceptable rate for the sequence of print actuation requests, the system configured whereby if presented with an actuation period of less than the minimum actuation period then the presented rate of print actuation requests is adjusted by altering the actuation event and/or the discarding of stripe data, to minimise print defects.

Abstract: A method of screening a continuous-tone image is configured to produce an output image to be printed on a surface. The continuous-tone image comprises a plurality of pixels having respective corresponding intended print locations. The method includes selecting a first sequence comprising a subset of the plurality of intended print locations, the first sequence being selected based on properties of the plurality of intended print locations. For each intended print location in the first sequence, the method also includes identifying the corresponding pixel in the continuous-tone image to obtain a second sequence for an error diffusion process comprising the identified corresponding pixels in the continuous-tone image.

Abstract: A method of screening a continuous-tone image is configured to produce an output image to be printed on a surface. The continuous-tone image comprises a plurality of pixels having respective corresponding intended print locations. The method includes selecting a first sequence comprising a subset of the plurality of intended print locations, the first sequence being selected based on properties of the plurality of intended print locations. For each intended print location in the first sequence, the method also includes identifying the corresponding pixel in the continuous-tone image to obtain a second sequence for an error diffusion process comprising the identified corresponding pixels in the continuous-tone image.

Abstract: A printing system for printing images formed of pixels on a substrate, the system comprising a print system arranged where print-heads traverse a substrate, the print system arranged to receive a sequence of print actuation requests in order to print each pixel of an image upon the substrate, the print system having an acceptable rate for the sequence of print actuation requests, the system configured whereby if presented with an actuation period of less than the minimum actuation period then the presented rate of print actuation requests is adjusted by altering the actuation event and/or the discarding of stripe data, to minimise print defects.

Abstract: A method for driving a capacitive load using a target voltage waveform having a peak voltage and an average rise and fall slew rate, wherein the average rise and fall slew rates comprise at least one voltage step, the method comprising supplying power from an input to an output for charging a capacitive load to obtain a peak voltage and average rise slew rate in response to the target waveform; discharging the capacitive load to obtain an average fall slew rate in response to the target waveform, and returning the discharged power from the capacitive load to the input.

Abstract: A driver circuit (1) for driving a capacitive load (2) with a drive pulse having a rise time, a predetermined voltage period and a fall time. The driver circuit (1) includes an inductance (6), switches (10, 11, 12), and a transformer (8) having a primary side (8) and secondary side (9). The switches (10, 11, 12) are controlled by a controller (13) to charge the inductance (6) from a power supply (4), and, when the capacitive load (2) is to be driven, to enable a charge path from the inductance (6) to the capacitive load (2) during the rise time, to disable the charge path during the constant peak voltage period and to enable a discharge path via the primary side (8) of the transformer (7) during the fall time. As the capacitive load (2) discharges through the primary side (8) of the transformer (7), charge is induced on the secondary side (9) of the transformer (7) and is used to charge the inductance (6), thereby saving power and enabling a lower voltage power supply to be used.

Abstract: A method for driving a capacitive load using a target voltage waveform having a peak voltage and an average rise and fall slew rate, wherein the average rise and fall slew rates comprise at least one voltage step, the method comprising supplying power from an input to an output for charging a capacitive load to obtain a peak voltage and average rise slew rate in response to the target waveform; discharging the capacitive load to obtain an average fall slew rate in response to the target waveform, and returning the discharged power from the capacitive load to the input.

Abstract: A driver circuit (1) for driving a capacitive load (2) with a drive pulse having a rise time, a predetermined voltage period and a fall time. The driver circuit (1) includes an inductance (6), switches (10, 11, 12), and a transformer (8) having a primary side (8) and secondary side (9). The switches (10, 11, 12) are controlled by a controller (13) to charge the inductance (6) from a power supply (4), and, when the capacitive load (2) is to be driven, to enable a charge path from the inductance (6) to the capacitive load (2) during the rise time, to disable the charge path during the constant peak voltage period and to enable a discharge path via the primary side (8) of the transformer (7) during the fall time. As the capacitive load (2) discharges through the primary side (8) of the transformer (7), charge is induced on the secondary side (9) of the transformer (7) and is used to charge the inductance (6), thereby saving power and enabling a lower voltage power supply to be used.