A mechanism for advancing and retarding the injection timing of a mechanically-actuated fuel injection pump. A frequency of the AC voltage is 10 kHz or higher. The method determines, for each of the detected signals, if the detected signal is out of focus, and applies a corrective voltage to each liquid lens that corresponds to a detected terahertz signal that is out of focus, wherein the corrective voltage adjusts a focus of the detected signal. The voice signal detection portion is configured to detect a communication status, control the self-adaptive filter according to the communication status, and control startup of the path change detection portion according to the communication status. The first maximum output luminance value is proximate to the maximum pixel value of the original image. Due to this, bending forces are continuously exerted on a thin plate-like fin material in a direction where the bending deformation of the fin material is cancelled, during the fin forming process.