In a display device of the invention, driving of the piezoelectric element is controlled to change the light path of the propagating light inside a light guiding plate. The nozzle assembly includes a paint orifice for discharging the supplied paint along an axis, a plurality of atomizing air orifices for discharging atomizing air to atomize the paint dispensed through the paint orifice and a plurality of shaping orifices for discharging shaping air to form the paint dispensed through the paint orifice into a predetermined pattern. The receive modem analyzes a number of these transmission levels to determine whether the levels have certain characteristics associated with the particular encoding law followed by the central office codec. In addition, two different modes, either layer by layer or layer to layer, are disclosed for the fabrication of organic semiconductor material-based devices, wherein all semiconductor organic materials required by the function of the desired device are deposited under an non-vacuum environment. According to the invention, to detect NH3 slippage, which indicates the transition from the overdosing phase to the underdosing phase, a variable which is characteristic of the NOx conversion is continuously measured during the overdosing phase, and in the event of a fall in the NOx conversion, it is inferred that NH3 slippage is present.