A demodulation circuit generates information related to the frequency of error correction, and feeds the information to a CPU. Accordingly, by replacing a previously mounted fluorescent lamp, the LED unit drives pulses at a high frequency and lights up for illumination, regardless of whether a ballast of an illumination device is of a glow starter, rapid starter or inverter lighting type. Further, when the resist spreads to the area of the contact hole when the amount of the resist to be applied and the surface state of the base are not fully controlled, contact defect would occur. The windings are so configured that the number of phases and the number of poles can be dynamically adjusted.