Birefringent optical films have a Brewster angle which is very large or is nonexistent. The first and second parties are informed of the needs and availabilities by the service provider. The flip-flops operate as a shift register at a scan path test, and when the third circuit exchanges signals with the second circuit through the flip-flops of the first scan chain, the second scan chain of the first circuit operates as a shift register. The stand-alone power generation device is electrically connected to the auxiliary system. During the time of no input of the differential signal, the threshold adjustment control section changes the first detection level adjustment signal so that the threshold voltage monotonically increases or decreases until the detection signal is inverted, to determine the first detection level adjustment signal that makes the threshold voltage appropriate, and outputs the determined signal.