A battery pack includes multiple power bus lines connecting a quantity of cell strings in parallel, wherein each cell string includes multiple cells connected in series. The input portion inputs color image signals which correspond to recording color material amounts. The high-definition image I is expressed in range and cross-range as IminHR, where is a weighting vector and R is a covariance matrix of the image data. The number of manufacturing steps of an energy storage device is reduced. When a cooling gas is jetted radially inward through the gas jetting holes of the temperature-reducing purge ring, a vacuum is created between the lower surface of the face plate and the upper surface of the temperature-reducing purge ring. Terminals are mounted on the head slider and are connected to the magnetic head unit.