A pixel 3 includes a pixel electrode 31 and opposed electrodes 32 for generating electric fields between a pair of substrates in directions substantially parallel to the substrates and also includes two regions S1 and S2 defined by the pixel electrode 31 and the opposed electrodes 32. The inner front end of the tappet shaft, which is thermally dimensionally stable, is provided with a guiding shoe or at least provided with a slide-resistant coating opposite a radially elastically compressible head. The invention further provides a polyarylene and an aromatic sulfonate derivative that are suitably employed in the above production method.