Image forming apparatus

An image forming apparatus, comprising:

• an inkjet recording unit configured to eject ink to a sheet using arranged plural nozzles and perform printing;
• a sheet transportation unit configured to transport the sheet;
• a line sensor configured to scan a test pattern image printed on the sheet using the plural nozzles and generate a test pattern scanned image;
• and
• an ejection malfunction determination unit configured to determine whether each nozzle among the plural nozzles is an ejection malfunction nozzle or not on the basis of a density distribution of the test pattern scanned image corresponding to this nozzle;
• wherein the test pattern image includes a synchronization mark formed by a predetermined reference position nozzle among the plural nozzles;
• the line sensor comprises plural sensor units;
• the plural sensor units partially scan the test pattern image respectively as the test pattern scanned image, and generate plural partial test pattern scanned images, respectively;
• scanning areas of the plural sensor units have an overlapping section in a perpendicular direction to a transportation direction of the sheet;
• the synchronization mark is formed such that the synchronization mark passes through the overlapping section;
• and
• the ejection malfunction determination unit (a) determines positions corresponding to a part of the plural nozzles in the partial test pattern scanned image on the basis of a position of the synchronization mark in the partial test pattern scanned image, and (b) determines whether a nozzle corresponding to the determined position is an ejection malfunction nozzle or not on the basis of a density at the determined position.