Patent ID: 7158747

Claim:
A belt-type fixing device, comprising: an endless sheet-like fixing belt to be heated wound around a supporting member and around a one-piece nip forming member that is fixed in a position away from the supporting member so as to be incapable of rotating, and a pressurizing roller which can be driven to rotate, which is in pressure contact with the nip forming member with the fixing belt interposed between, and of which part in contact with the fixing belt forms a fixing nip, wherein a surface of the one-piece nip forming member that is opposite to the pressurizing roller is configured as a curved surface extending along an outer circumferential surface of the pressurizing roller so that a pressure distribution in the fixing nip is made generally flat with respect to a paper feeding direction, the fixing belt is rotated while being slid on the nip forming member by rotational drive of the pressurizing roller, and a contact area between the fixing belt and the one-piece nip forming member outside the fixing nip is smaller on an entrance side of the fixing nip than on an exit side of the fixing nip.