A frame rate controller method and system are provided. The machine tool fixes work, which has an upper flat surface and a lower bent surface, in a state wherein the upper flat surface is horizontally disposed, and makes a hole in the lower bent surface. The image sensor comprises a N-wellP-substrate type photodiode with borderless contact and dielectric structure covering the photodiode region. An amount of electric charges induced on a surface of the recording medium, which has been conveyed to a recording position where the droplets of the recording liquid are discharged from the recording head toward the recording medium, is adjusted in accordance with a resistance value of the recording medium.