FIXING DEVICE AND IMAGE FORMING APPARATUS

To provide a fixing device that can cut off power supply to first and second heat sources before the temperature of the ends of a fixing member increases to a predetermined abnormal temperature or more, and can favorably fix images at the ends in a width direction of a recording material with the maximum width size, and to provide an image forming apparatus.SOLUTION: The ratio (maximum heat generation ratio Rp) of the calorific power at maximum heat generation parts with the largest calorific power on both sides of a second heat source such as a sub-heater to the calorific power at the center is 150% or less, and the ratio (end heat generation rate Rq) of the calorific power at parts corresponding to the width direction ends of the maximum width size of the second heat source to the calorific power at the center is 130% or more. The half value width of end areas on both sides of the second heat source and having a higher calorific power than the calorific power at the center is 65 mm or less.SELECTED DRAWING: Figure 3 【課題】定着部材の端部が、所定の異常温度以上となる前に第一および第二加熱源への電力供給を遮断でき、かつ、最大サイズ幅の記録材の幅方向端部の画像を良好に定着できる定着装置および画像形成装置を提供する。【解決手段】サブヒータなどの第二加熱源の両側の最も発熱量が多い最大発熱箇所の中央の発熱量に対する発熱量の比率（最大発熱比率Ｒｐ）が１５０％以下であり、第二加熱源の最大サイズ幅の幅方向端部に対応する箇所の中央の発熱量に対する発熱量の比率（端部発熱比率Ｒｑ）が、１３０％以上である。また、第二加熱源の両側の発熱量が中央の発熱量よりも高い端部領域の半値幅が６５ｍｍ以下である。【選択図】図３