A flexible substrate that is curved in a first direction, an insulator disposed on the substrate, a first electrode disposed on a first main surface side of the insulator in a first formation region, and a second electrode also disposed on the first main surface side of the insulator in a second formation region. A non-formation region is defined between the first electrode and the second electrode on the first main surface, and the non-formation region has at least a portion thereof extending along a direction different from a second direction orthogonal to the first direction.