Preferable examples of a plastic material of the film constituting the transparent substrate include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamide, polyether, polysulfone, polyethersulfone (PES), polycarbonate, polyarylate, polyether imide, polyether ether ketone (PEEK), polyimide and aramid.