| 摘要 |
An image fixing apparatus is formed by a fixing roller which contacts an image surface of a recording mediums and performs fixing, a pressure roller which is urged against the fixing roller to thereby apply a necessary pressure needed for fixing of a toner image upon the recording medium, and an external heating roller which has an internal heat surface and when urged against the fixing roller, keeps a surface layer of the fixing roller at a predetermined temperature which is necessary for fixing. A heat transfer coefficient of the fixing roller is 20 W/m2.K to 100 W/m2.K. This guarantees a necessary fixing nip width which is needed for fixing of images without increasing the size of the apparatus or remarkably increasing a holding pressure at the fixing nip portion. Further, it is possible to stably maintain an appropriate fixing temperature without increasing the temperature gradient of the surface layer portion for adding a filler material to the surface layer. In an image forming apparatus using such an image fixing apparatus, stable and high-quality fixing of images one at a time not to mention, but also even continuously is realized.
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