Abstract: A piezoelectric ceramic material composed of a ternary solid solution of Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3 - PbTiO.sub.3 - PbZrO.sub.3 having the composition within an area encircled by lines connecting points A(15 mol % of Pb(Ni.sub.1/3 Nb.sub.170 )O.sub.3, 45 mol % of PbTiO.sub.3 and 40 mol % of PbZrO.sub.3), F(40 mol % of Pb(Ni.sub.166 Nb.sub.2/3)O.sub.3, 30 mol % of PbTiO.sub.3 and 30 mol % of PbZrO.sub.3), C(51 mol % of Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3, 24 mol % of PbTiO.sub.3 and 25 mol % of PbZrO.sub.3), G(45 mol % of Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3, 35 mol % of PbTiO.sub.3 and 20 mol % of PbZrO.sub.3), H(40 mol % of Pb(Ni.sub.1/3 Nb.sub.170 )O.sub.3, 40 mol % of PbTiO.sub.3, and 20 mol % of PbZrO.sub.3) and I(30 mol % of Pb(Ni.sub.1/3 Nb.sub.2/3)O.sub.3, 45 mol % of PbTiO.sub.3 and 25 mol % PbZrO.sub.3). And at least one additive selected from the group consisting of Sb.sub.2 O.sub.3, Nb.sub.2 O.sub.5, Bi.sub.2 O.sub.3, La.sub.2 O.sub.3, WO.sub.

Abstract: A link rod for driving wiper blades is coupled to and driven by a crank arm by means of an eccentric bush, so that an effective length of the link rod can be changed. A stopper portion is provided on the link rod for maintaining, during a normal operation, the eccentric bush in such a position where the effective length is smallest. A driving mechanism including three gears meshing with each other drives the eccentric bush when a wiping operation should be stopped so that the eccentric bush is rotated and placed at a position where the effective length of the link rod becomes largest, whereby the wiper blades are held in concealed positions during the blades are out of operation.