Photocopying – Projection printing and copying cameras – With developing
Patent
1990-06-29
1992-03-17
Brown, Brian W.
Photocopying
Projection printing and copying cameras
With developing
355 30, 355 77, G03B 2732
Patent
active
050972880
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.
REFERENCES:
patent: 4367037 (1983-01-01), Nishikawa
patent: 4609278 (1986-09-01), Taniguchi
patent: 4827356 (1989-05-01), Yamamoto et al.
patent: 4864356 (1989-09-01), Asano et al.
Akao Michitoshi
Kato Tokunori
Brother Kogyo Kabushiki Kaisha
Brown Brian W.
Dang Khanh
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