Fixing device and image forming device

Abstract

A fixing device having a good fast-copy-out performance. The fixing device comprises a heating roller (1), a pressurizing roller (2), an induction coil (3a) for producing a magnetic flux, and a temperature detecting member (thermistor, etc) (5) for detecting the temperature of the heating roller (1). A magnetic flux produced by the induction coil (3a) produces an eddy current in the heating layer of the heating roller (1) to heat the roller (1) by induction heating. The temperature detecting member (5) is disposed in a area having a calorie of at least Q / e within the heating area of the roller (1), where Q is the maximum value of a calorie distribution in the heating area of the roller (1). A heating roller (1) temperature controlled based on a detection result by the temperature detecting member (5) prevents a heating roller (1) temperature from rising abnormally. While the fixing device is on stand-by, the roller (1) is heated while rotating.

Description

technical field [0001] The present invention relates to a fixing device for fixing a toner image on a recording material by heating and pressing, and an image forming apparatus using the fixing device. Background technique [0002] Conventionally, in electrophotographic image forming apparatuses, small-sized heating roller-type fixing devices capable of stable fixing have been widely used. Such a heating roller-type fixing device is configured as follows: a heating roller that heats and conveys a recording paper on which a toner image composed of powder developer (toner) is transferred; And convey the pressure roller of the recording paper, and make the recording material (paper) pass through the fixing point as the pressure contact portion (nip portion) between these heating rollers and the pressure roller, so that the toner image is melted and pressure-coated ( Fixing) on ​​the recording material. [0003] A heating method using a heater lamp is employed in a heating rol...

AI Technical Summary

Problems solved by technology

That is, when comparing position S1 and position S2, since the detection sensitivity of position S2 is slow, it can be seen that the temperature of the heating area near the induction coil cannot be controlled with high precision.

Therefore, if the temperature detection member is arranged at position S2 (non-heating area), the worst case is that the temperature of the heating area near the induction coil will rise abnormally, causing the risk of smoke and fire of the heating roller.

In addition, there are also cases where the heat-resistant temperature of the heating roller is exceeded, resulting in damage or degradation of the heating roller.

[0019] Here, with regard to the temperature control of the heating roller, the above-mentioned JP-A-10-104975 describes that the installation position of the temperature detection member is provided in the non-heating area, but when the temperature detection member is provided at this position, For the above reasons, it is difficult to heat the heating roller in a stopped state during standby, so the heating roller must be heated from room temperature every time an image is output, so that a good fast copying time cannot be obtained

Also, in the above-mentioned Japanese Patent Laid-Open No. 2002-72755, it is also described that a temperature detection member is provided in a non-heating region between the coils, but the vicinity between the coils is also a part where the generation of eddy current becomes smaller, thereby causing the same problem as above.

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