Patent ID: 8515324

Claim:
A fixing device comprising: an endless, rotatable fixing member; a rotational pressing member rotatably provided in contact with the fixing member; a nip formation member disposed opposite the rotational pressing member via the fixing member to form a fixing nip between the fixing member and the rotational pressing member; and an urging unit disposed opposite the rotational pressing member via the nip formation member and the fixing member to push against and deform the nip formation member to change a curvature of a contact face between the fixing member and the rotational pressing member at the fixing nip, wherein the urging unit, the rotational pressing member, and the nip formation member satisfy a relation of 1/ r> 1/ R> 1/( r+t ) where r represents a radius of the rotational pressing member, 1/r represents a curvature of the fixing nip, R represents a distance between a rotation center of the rotational pressing member and an end portion of the urging unit, 1/R represents a curvature of the end portion of the urging unit, and t represents a thickness of the nip formation member.