Abstract: In a multinozzle ink jet printing system, a closed loop servo system drives the drop generator so that the distance between the streams at which ink droplets are detached is maintained at an optimum range. One or more sensors are positioned downstream from the multinozzle plate of the ink jet printing system. The sensors sense the flight time of ink droplets and output signals which are developed into a variable voltage for controlling the drop generator.

Abstract: An inner cylindrical tube has its outer cylindrical surface spaced from an inner cylindrical surface of outer means to have an ink cavity therebetween from which ink is supplied through one or more ink jet nozzles. At least the inner tube is a piezoelectric material so that the inner tube vibrates radially when electrically excited to produce vibrations at a desired operating frequency whereby a stream of ink droplets is supplied from each of the ink jet nozzles. The spacing between the inner surface, which has its longitudinal axis coaxial with the longitudinal axis of the inner cylindrical tube, of the outer means and the outer surface of the inner cylindrical tube is selected so that the ink cavity is resonant at the operating frequency of the inner cylindrical tube.

Abstract: The invention relates to an ink jet printer and in particular to correcting the flight path of drops from the printer to reduce print position error on the print media. It has been found that drops as far as 30 drop positions ahead of a drop in the ink stream can have an effect on the flight path of that drop to the print media. Using a memory to store 2.sup.30 compensation values to correct the flight of the drop for all possible combinations of drop patterns in the ink stream is not practical. Disclosed herein is a method and apparatus for using a smaller number of compensation values to correct the flight path for all possible combinations. This is accomplished by grouping the drops remote in position from the drop being compensated into blocks of drops and treating the entire block of drops as contributing one effect on the flight of the drop.

Abstract: Insertion of guard drops on a variable basis within a drop segment of an ink jet raster has been found to be highly successful in producing quality printing. A typical sequence isPgPgPgPggPgggPPgP .rarw. timewhere P designates a printed drop and g a guard drop. The drop on the right is the leading drop of the segment.