3D surface printing apparatus for the edge area of substrate

A 3D surface printing apparatus for an edge area of a substrate, the apparatus comprising:

• a nozzle assembly that comprises a nozzle that is disposed outside of a side surface of the substrate, configured to eject ink in a direction parallel to a surface of the substrate, through Electrohydrodynamic (EHD) jetting by applying a voltage to an electrode;
• an actuator configured to move the nozzle back and forth in a direction normal to the surface of the substrate around a rim of the substrate;
• and
• a controller that controls a printing operation,
• wherein the actuator is configured to print a pattern that is continuously extends along a front surface of the rim of the substrate, a side surface of the substrate, and a rear surface of the rim of the substrate while moving the nozzle back and forth,
• wherein the controller is configured to control the printing operation based on a detected 3D electric field distribution, the distribution being determined according to a shape and material of a structure surrounding an area being printed and a previously-printed pattern, and
• wherein the controller is configured to control the printing operation by adjusting at least one of the voltage applied to the electrode, a flow rate of ink ejected from the nozzle, and a moving speed of the nozzle as printing proceeds, in response to changes in the 3D electric field distribution, so as to minimize an effect of the changes in the 3D electric field distribution caused by changes in the shape and material of the structure surrounding the area being printed and caused by the previously-printed pattern.