The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 15, 1994
Filed:
Dec. 20, 1991
Atsushi Arai, Ichikawa, JP;
Hirobumi Yoshino, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
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.