Image forming apparatus

摘要

An image forming apparatus having: an endless fixing belt; a heating member heating the fixing belt; a support member maintaining the fixing belt substantially circular; a pressing member in contact with the fixing belt to form a fixing nip portion; a temperature sensor; a position detector; a storage storing temperatures and positions of the fixing belt detected by the temperature sensor and the position detector; and a control unit. The control unit is operable in a characteristic storing mode and in a fixing mode. In the characteristic storing mode, temperatures of the fixing belt associated with positions are detected, and the detected temperatures and positions are stored in the storage. In the fixing mode, temperatures of the fixing nip portion are predicted with reference to the temperatures and positions stored in the storage, and the heating member is controlled such that the predicted temperatures become a target temperature.

主权项

1. An image forming apparatus wherein a toner image transferred to a sheet is fixed thereon by heat, the image forming apparatus comprising:
an endless fixing belt located to come into contact with the toner image; a heating member configured to apply heat to the fixing belt from an inside or an outside of the fixing belt; a support member located in a space enclosed by the fixing belt and configured to maintain the fixing belt in a substantially circular form; a pressing member in contact with an outer circumference of the fixing belt to form a fixing nip portion; a temperature sensor configured to detect a temperature of the outer circumference of the fixing belt; a position detector configured to detect a position of the fixing belt in a circumferential direction; a storage configured to store the temperature detected by the temperature sensor and the position detected by the position detector; and a control unit configured to control at least the heating member, the temperature sensor, the position detector and the storage, wherein: the control unit is operable in: a characteristic storing mode to be carried out at a time other than a fixing operation, in which temperatures of the fixing belt associated with positions in the circumferential direction are detected by use of the temperature sensor and the position detector, and the detected temperatures and positions are stored in the storage; and a fixing mode to be carried out during the fixing operation, in which temperatures of the fixing nip portion is predicted with reference to the temperatures and the positions stored in the storage, and the heating member is controlled such that the predicted temperatures become a target temperature.