US Patent 7510254 Image forming apparatus and method thereof

An image forming apparatus and a method thereof for preventing degradation of image quality by a malfunctioning nozzle are disclosed. The image forming apparatus includes a print head including a first nozzle line having a plurality of nozzles arranged with a predetermined pitch I and a second nozzle line disposed at predetermined distance D from the first nozzle line and having a plurality of nozzles arranged to be deviated from the nozzles of the first nozzle line with a predetermined pitch I. A controller controls the print head to inject ink to form at least a portion of dots to be overlapped by ink injected from the nozzles of the first nozzle line.