Method for aligning a plurality of nozzle tips

A method for aligning a plurality of nozzle tips, the method comprising:

• a first nozzle aligning step of setting a reference position of a first nozzle tip for discharging ink within a working area through an image of a first camera observing the working area above a substrate and a second camera observing the working area in an inclined direction;
• a second nozzle aligning step of setting a reference position of a second nozzle tip for discharging ink within the working area through the image of the first camera and the second camera;
• a step of detecting a position of a substrate based on the image of the second camera;
• and
• a printing preparation step of positioning the first nozzle tip and the second nozzle tip to a printing position on the substrate,
• wherein after the first nozzle aligning step and the second nozzle aligning step, a step of moving the first nozzle tip and the second nozzle tip to designated positions is performed, wherein each designated position is spaced apart by a certain distance from the reference position.