A dryer includes a sealed drum, a heat pump system, a vacuum device and a steam generating device. The lane information is ascertained from an image recorded by an image sensor andor estimated on the basis of objects in this image depending on the weather conditions. Such construction permits a noise component at a different phase as well as that at the same phase to be effectively removed during synthesis of the measurement signal, to thereby reduce an error in measuring by the linear scale. At least part of the unified storage zone is allocated to a site as site data. In an embodiment, the processing is carried out by dipping the metal into the solution for 60 seconds or less, followed by drying for 10 seconds or less, for a total processing time of 70 seconds or less.