Patent ID: 8364051

Claim:
A fixing device to fix a toner image on a sheet of recording media, comprising: a cylindrical fixing member, having an external circumferential surface including at least one crown portion projecting radially outward from the surface of the fixing member and at least one inverted-crown portion curved radially inward from the surface of the fixing member, having a thickness smaller than a thickness of the crown portion; a pressing unit including a facing surface facing the fixing member, in which at least one convexity projecting toward the fixing member and at least one concavity recessed away from the fixing member are formed, the pressing unit pressing against the fixing member while the crown portion of the fixing member matches the concavity of the pressing unit and the inverted-crown portion of the fixing member matches the convexity of the pressing unit, forming curved fixing nip therebetween, and when the fixing member and the pressing unit are in contact with each other with no pressure generated therebetween, no gaps exist between the crown portion and the inverted-crown portion of the fixing member and the concavity and the convexity of the pressing unit; a first heating member including a first heating portion to heat the fixing member partially in an axial direction of the fixing member, the first heating portion disposed at a position corresponding to the crown portion of the fixing member in the axial direction; a second heating member including a second heating portion to heat the fixing member partially in the axial direction of the fixing member, the second heating portion disposed at a position corresponding to the inverted-crown portion of the fixing member in the axial direction; a temperature detecting unit to detect a surface temperature of the fixing member; and a controller to independently control the first heating member and the second heating member.