A method and apparatus for converting a digital video signal, to a signal having a resolution that matches a display device, by using simple hardware alone. The upper portion of the clip portion and the attachment arm portions are fitted into the space between a flange outer periphery portion, and the end part of a metallic filament W is retained through elastic force. The alloy is then heated at a lower elevated temperature to cause the precipitation of a portion of the chromium as an aluminum-containing and chromium-containing intermetallic compound.