Printing apparatus for printed electronics

A printing apparatus for printed electronics, the printing apparatus comprising:

• ejection head units which each have at least one nozzle for ejecting ink droplets to perform drop-on-demand or continuous printing;
• a jetting observation unit which is provided at one side of the at least one nozzle and configured to observe the ink droplets ejected from the at least one nozzle;
• a lighting unit which is provided at another side of the at least one nozzle and configured to provide light to the jetting observation unit;
• an alignment observation unit which is configured to observe an aligned state between the at least one nozzle and a substrate;
• an X-Z plate which is connected to the alignment observation unit, the lighting unit, the ejection head unit and the jetting observation unit;
• and
• a fluid supply unit which includes a syringe pump and is configured to supply ink to the at least one nozzle,
• wherein the ejection head units include a single-nozzle head unit, and a multi-nozzle head unit provided separately from the single-nozzle head unit,
• wherein the jetting observation unit includes an arc-shaped arc frame which is mounted on the X-Z plate and has a predetermined curvature, an arc slot which is penetratively formed at a central portion of the arc frame and has a curvature corresponding to the predetermined curvature of the arc frame, a movable unit which is configured to move along the arc slot and an image capturing unit which is provided on the movable unit and configured to acquire a jetting image, and
• wherein the alignment observation unit captures an image of the substrate, observes the substrate, calculates offset distances between the alignment observation unit and the ejection head units and controls or determines positions of the ejection head units by using the calculated offset distances, and
• wherein the alignment observation unit, the lighting unit, the ejection head unit and the jetting observation unit are moved together with the X-Z plate in the X-axis direction and the Z-axis direction, and
• wherein the single-nozzle head unit includes a head holder fastened to a holder mounting unit fixed to the X-Z plate and a single nozzle mounted in the head holder, and
• wherein the head holder includes a first seating surface at one side thereof and a second seating surface having a level difference from the first seating surface, and the holder mounting unit is seated on the first seating surface,
• wherein a width of the second seating surface is smaller than a width of the first seating surface, such that the lighting unit is prevented from interfering with the head holder,
• wherein the first seating surface includes a protruding portion which is adjacent to the second seating surface, and the protruding portion is configured to guide the holder mounting unit such that the holder mounting unit does not deviate from the first seating surface, or the protruding portion is configured to guide an initial position of the holder mounting unit when the holder mounting unit is mounted.