Printing apparatus

Abstract

An inkjet printer in which a printhead defines an elongate array of orifices from which jets of ink are projected into a space within which substrates to be printed are presented. An air curtain generator fixed in position relative to the printhead extends along one side only of the array of orifices so as to direct a curtain of air across the array a of orifices and across an open portion of the printhead on the side of the array of orifices remote from the air curtain generator. The air curtain cleans the printhead. A pressure pulse may be applied to ink within the printhead sufficient to discharge ink form each orifice when not in use to project ink. The pressure pulse has a relatively rapidly rising leading edge and a relatively slowly falling edge. An ink reservoir is coupled to the printhead for supplying ink to the orifices. The orifices may be arranged in at least two vertically offset groups, the reservoir being divided into vertically offset reservoir sections including a lowermost section and an upper section with each reservoir section being coupled exclusively to a respective group of orifices. The upper reservoir section is arranged to overflow into the immediately adjacent reservoir section which is spaced therebelow. Each reservoir section includes an ink level detector, and ink is supplied to the reservoir section which is vertically uppermost if any level detector detects an ink level below a predetermined level.