An array of non-packaged LED dies is sandwiched between at least two transparent substrates having conductors bonded to the electrodes without wires. The support shaft is movable in a plane perpendicular to an axial direction thereof, and the print head includes an aligning member interlinked with the print head for contacting with an outer periphery of the support shaft when the print head is moved toward the platen. A method of designing lighting systems, including analysis of whether or not to add air cooling to increase light source efficiency is also disclosed.