| 摘要 |
PROBLEM TO BE SOLVED: To provide a comparatively compact heater unit having a comparatively simple mechanism, configured to prevent excessive temperature increase of a non-paper-passing area in a fixation rotating body, such as a fixing belt, and to provide a fixing device and an image forming device.SOLUTION: A pair of shielding plates 51, 52 are arranged separately in a circumferential direction so as to form an opening 52a which exposes heaters 25A, 25B in a part of the circumferential direction. The opening 50a is formed so that circumferential lengths R1-R3 of the opening are gradually increased from a lateral end toward a lateral center. A support member 53 for supporting the lateral ends of the shielding plates 51, 52 moves in a lateral direction, in contact with the lateral ends of the shielding plates 51, 52, to move the shielding plates 51, 52 so as to vary the lengths R1-R3 of the opening 50a. |
