A fixing device includes: a heat source, a heating member, a pressure member, a heat absorption unit, a holding member, and an end part supporting member. An exemplary method includes dividing the information file into a first file and a second file, wherein the second file includes content from the information file to preclude reconstruction of the information file using only the first file, and encrypting the second file. A controller controls the de-correlation based upon the adaptation state of the adaptive filters. The invention is characterized in that the groove is continuously widened in a transition portion adjoining the groove portion, in order to merge into a bevel in a bevel portion adjoining the transition portion. The offset code is fed back to a delay locked loop circuit and aligns the middle points of the output data signal with the edges of the external clock signal.