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:
Mar. 17, 1992
Filed:
Jun. 29, 1990
Michitoshi Akao, Nagoya, JP;
Tokunori Kato, Ichinomiya, JP;
Brother Kogyo Kabushiki Kaisha, Nagoya, JP;
Abstract
An image forming apparatus has a thermal fixing device having a first thermistor in the thermal fixing device for detecting the temperature in the thermal fixing device and a second thermistor being substantially at the center of the apparatus out of the thermal fixing device for detecting the temperature in the apparatus. In the image forming apparatus, the temperature detected by the second thermistor is compared with two predetermined reference temperatures T1 and T2 (T1<T2) repectively. The thermal fixing device is thermally controlled by the first thermistor based on a first preset current IA of the device when the temperature detected by the second thermistor is lower than the reference temperature T1 and controlled by the first thermistor based on a second preset current IB (IB<IA) preset in the device when the temperature detected by the second thermistor is in the range between T1 and T2, and further controlled so as to stop heating of the device when the temperature detected by the second thermistor is higher than the reference temperature T2. By such an image forming apparatus, the temperature both inside and outside the fixing device can be constantly controlled and, therefore, sensitivity change of the photosensitive and pressure sensitive medium used in image forming can be prevented so as to be able to stably form the image on the medium. At the same time, a warm-up time can be shortened by applying initially higher current to the heating device, which current is then lowered for steady state control.