Disclosed is a power supply circuit for vehicles, which can continuously supply a constant voltage without a complicated circuit configuration, even during a time when a surge voltage is applied. A signal processing module is provided for processing the first high-resolution image output stream and producing a reduced-area high-resolution image output stream containing image information for only a selected portion or portions of the original image and a wide-area low-resolution image output stream. Alternatively, the method includes a step of spraying a slurry for forming an enamel layer onto a surface of a substrate, wherein the substrate is vibrated when the slurry is applied or when the slurry applied is still fluid. A frequency generator having an input connected to the first matrix output and connected to a number of frequency outputs of the master clock generation unit, derives an output reference frequency from the primary clock, and provides it at the frequency outputs.