Inkjet printers find uses in a wide range of applications. Reductions in ink drop application sizes have made inkjet printers useful in color printing, such as the printing of photographs.
When rows or columns of nozzles are used to eject drops to form an image, small horizontal and/or vertical bands may be created by a plugged or malfunctioning nozzle. Horizontal and/or vertical bands also may be caused by directionality errors in ejected drops. Depending on manufacturing variations in the printhead, ejected drops may not always be ejected exactly perpendicular to the print medium. The bands created by such plugged nozzles, malfunctioning nozzles, and/or ejection directionality may be detected by the human eye thereby diminishing the quality of the printed image.
There are methods that may be used to detect nozzles that are not working properly. Such methods may be fairly expensive to implement in a consumer product. If a non-functioning nozzle is detected, compensation may be made by passing another working nozzle over the portion of the image associated with the non-functioning nozzle. However, high-speed printing may be done with only one or two passes of the nozzles over the same location on an image that is the printed. This makes it difficult to compensate for non-functioning nozzles. This is especially difficult for page wide array printheads. Since the printhead of a page wide array does not move, there may be no opportunity to use another nozzle to compensate for the plugged or malfunctioning nozzle.