Inkjet interlace printing with inclined printhead

Abstract

An inkjet printer is disclosed for printing on a moving web in which at least two rows of nozzles are arrayed on a nozzle plate such that they form an oblique angle with the direction of movement of the moving web. The drops to be printed are charged so that they are deflected so that vertically adjacent nozzles from each of the two rows print overlapping interlaced drops to form a single print row on the moving web. The nozzles in one row are slightly offset from direct vertical alignment with the nozzles in the second row, so that the charging pattern to be applied to the drops generated is highly simplified. Charging is accomplished by a charge plate having slots extending into the plate to a sufficient depth so that the plate may be moved into position after the streams have been started, and may be withdrawn from position before the ink drop streams are turned off. Although the use of slotted charge plates may use two plates, in a preferred form a single plate is used, with alternate slot being of varying depth to allow the passage of streams from the first and second parallel rows. Adjacent cavities may be stimulated by a single acoustic cavity driven by a single stimulator. In this way, the system is adaptable to use for color printing, with a single cavity driving up to four fluid cavities; in this case, a pair of slotted charge plates having slots of sufficient depths to allow the passage of the inkjet streams from four adjacent rows would be utilized.