A fluid dynamic bearing device includes a sleeve having a bearing hole into which a shaft is inserted, the sleeve rotatably supporting the shaft to make relative rotation about a center axis and a bearing housing made of a cold-rolled steel plate or a galvanized steel plate, the sleeve being received within the bearing housing. In one sample embodiment, a series of two-dimensional optical targets are placed outside the document scanning area. A bit counter keeps track of the number of bits remaining and determines if sufficient bits have been used to ensure that the fixed-length compressed data block will be filled. In at least one exemplary embodiment, the maleic anhydride copolymer is a maleic anhydride-butadiene copolymer partial ammonium salt.