Temperature control method for a fixing device

U.S. Patent Number: 5287155

Abstract: A method of controlling the surface temperature of a heat roller included in a fixing device and having a heater therein by sensing it by a thermistor. The thermistor is held in contact with the heat roller during warm-up operation and in a standby condition or spaced apart from the heat roller while a copying operation is under way. The heater is on/off controlled on the basis of a temperature measured when the thermistor is spaced apart from the heat roller. The method corrects this temperature by comparing temperatures measured in the contact and non-contact positions of the thermistor. In such a correction mode, if the difference between the two measured temperatures does not lie in a predetermined range, the method stops energizing the heater determining that an error has occurred.

Inventors: Arai; Atsushi (Ichikawa, JP), Yoshino; Hirobumi (Tokyo, JP)

Assignee: Ricoh Company, Ltd. (Tokyo, JP)

Application Number: 07/810,859

Issued: 1994-02-15

Expired: 2006-02-15

Classes: 399/69 ; 219/216; 399/320; 399/70

Field of search: 355/282,285,290,208,205,207 219/216,469,470,471 430/97-99,124

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