FIXING DEVICE AND IMAGE FORMING APPARATUS INCLUDING FIXING DEVICE

To provide a fixing device comprising a heat roller body having a driven gear attached to its one end, and prevent the generation of unusual sound caused by advanced rotation of the heat roller body.SOLUTION: A fixing device has a notch part 33a that is formed at an end of a heat roller body 33, a pair of projection plate parts 33b, 33c that are connected to two edges of the notch part 33a, and a transmission projection part 36e that is formed on a driven gear 36 and inserted into the notch part 33a. The transmission projection part 36e is in contact with one projection plate part 33b to transmit a rotation power of the driven gear 36 to the heat roller body 33. The driven gear 36 has a contact part 33g that is located on the front side in a roller rotation direction with respect to one projection plate part 33b. An interval k1 in the roller rotation direction between the contact part 33g and one projection plate part 33b is narrower than an interval k2 in the roller rotation direction between the transmission projection part 36e and the other projection plate part 33c.SELECTED DRAWING: Figure 8A 【課題】一端部に被駆動ギアが装着されるヒートローラー本体を備えた定着装置において、ヒートローラー本体の先回りに起因する異音の発生を防止する。【解決手段】定着装置は、ヒートローラー本体３３の端部に形成された切欠部３３ａ、切欠部３３ａの二つの端縁に接続された一対の突出板部３３ｂ，３３ｃと、被駆動ギア３６に形成され、切欠部３３ａに挿入される伝達突部３６ｅとを有している。伝達突部３６ｅは、一方の突出板部３３ｂに当接することで被駆動ギア３６の回転動力をヒートローラー本体３３に伝達する。被駆動ギア３６は、一方の突出板部３３ｂよりもローラー回転方向前側に位置する当接部３３ｇを有している。当接部３３ｇと一方の突出板部３３ｂとのローラー回転方向の間隔ｋ１は、伝達突部３６ｅと他方の突出板部３３ｃとのローラー回転方向の間隔ｋ２よりも狭い。【選択図】図８Ａ