METHOD OF DESIGNING MASK FOR SELF-SCANNING LIGHT EMITTING DEVICES

PROBLEM TO BE SOLVED: To obtain an optimum mask designing method for making a metal wiring also serving as light-shielding layer for self-scanning light emitting devices. SOLUTION: A mask 42 for forming an Al wiring 26 is overlapped with an Au electrode 16, and its overlapped width W1 in the direction perpendicular to an array of switching elements is selected so as to satisfy W1>(S+dS)+a, where S is the etching quantity of the side face of the Al wiring 26, dS is the etching quantity variation, and (a) is the alignment deviation of the mask.