. "FIGS. 11A to 11D show a damper portion in a sixth embodiment, FIG. 11A is a plan view, FIG. 11B is a section view taken along the line P-P in FIG. 11A, FIG. 11C is a section view taken along the line Q-Q in FIG. 11A, and FIG. 11D is a section view taken along the line R-R in FIG. 11A;" . . .