US Patent 7214929 Force-feedback input device

A code disk rotates around the shaft fixed to a base in a case. A half of the upper surface of the code disk is exposed from the case. The code disk functions as an operating member on which an operator puts his or her finger to rotate it. A transparent body is layered under the code disk and fixed to the shaft. The transparent body is a circular film member including a piezoelectric element and a transparent electrode. A rotation angle of the code disk is detected by a light emitter and a light receiver. According to the rotation angle, alternating-current is applied to the transparent electrode of the transparent body to drive the piezoelectric element. External force is thus applied to the code disk from the transparent body.