Patent ID: 8840235

Claim:
A print head for printing optical structures on a substrate comprising: an ejection device for ejecting at least one droplet of a printing ink towards the substrate and a curing device for curing the at least one deposited droplet, wherein the curing device comprises at least one ultraviolet emitting light-emitting diode; wherein the at least one ultraviolet emitting light-emitting diode is at least two ultraviolet emitting light-emitting diodes and/or at least two light exit openings, wherein the at least two ultraviolet emitting light-emitting diodes and/or the at least two light exit openings are provided in such a manner that light cones emitted by each of the at least two ultraviolet emitting light-emitting diodes and/or the at least two light exit openings overlap each other in the area of the at least one deposited droplet; wherein the at least two ultraviolet emitting light-emitting diode are configured for being enabled sequentially; and wherein the power of the at least two ultraviolet emitting light-emitting diodes and/or of the ultraviolet light emitted by the at least two light exit openings are adjusted in such a manner, that the deposited droplets are substantially cured only in the overlapping area of the light cones emitted by each of the at least two ultraviolet emitting light-emitting diode and/or by each of the at least two light exit openings, in particular during a period of time shorter than 250 milliseconds.