The present invention relates to shape deformable materials, which are capable of being deformed, storing an amount of shape deformation, and recovering at least a portion of the shape deformation when exposed to a humid environment. A control unit for the ice making device controls the water-supply part, an ice tray drive part and an ice detecting part on the basis of variation of the electrostatic capacity between the electrodes of the electrostatic capacity sensor. The back surface has a radially inner end and a radially outer end, which are connected via a line segment. Each printhead integrated circuit has nozzle arrangements incorporating micro-electromechanical actuators for ejecting ink from respective ink chambers. A transverse acceleration and a vertical acceleration of the vehicle are detected, and the roll angle of the vehicle is estimated based on the detected transverse acceleration and the detected vertical acceleration.