A rule specifies a timing relation between a measurement configuration which indicates at least one subframe to measure and a reporting configuration which indicates at least one subframe in which to report. Arc discharge is determined to have developed in the glow-discharge apparatus, when VrVf increases to a second level or a higher level within a preset time To after the supply of power to the glow-discharge apparatus is stopped. A converter device is interconnected with the current controller device. The aforementioned steps are repeated until a predetermined condition for accuracy of the target color has been reached. A layer having n-dopant may also have substitutional carbon.