In a state in which a reference light source emits light, display elements of a display device are caused to light up in each of lighting patterns for causing any adjacent display elements not to light up simultaneously. The data is transmittable in a data light defined by a data wavelength defined relative to the illuminating light. A low-viscosity and water-soluble high molecular solution is coated on the focus metal mask to form a viscous interface. to either of an operating state and a resting state. The mask opening having the opening width increased toward the deposition source reduces the probability of deposit particles, obliquely scattered from the deposition source, hitting an end of the mask opening, whereby the deposit is prevented from being reduced in thickness on an end corresponding to the end of the mask opening as well as from nonuniformity of the thickness.