Fixing device and image forming apparatus

An image forming apparatus comprising:

• an image forming device configured to form an image on a recording medium;
• and
• a fixing device configured to fix the image on the recording medium,
• the fixing device including:
• a fixing rotator;
• an opposed rotator configured to contact the fixing rotator to form a nip between the fixing rotator and the opposed rotator;
• a heater configured to heat the fixing rotator,
• the heater including:
• a tube;
• a heat generating portion disposed inside the tube;
• a first sealing portion disposed at a first lateral end of the tube in a longitudinal direction of the fixing rotator, the first sealing portion including a first inboard end distanced from a first lateral end of the heat generating portion with a first distance in the longitudinal direction of the fixing rotator;
• and
• a second sealing portion disposed at a second lateral end of the tube in the longitudinal direction of the fixing rotator, the second sealing portion including a second inboard end distanced from a second lateral end of the heat generating portion with a second distance in the longitudinal direction of the fixing rotator, the second distance being smaller than the first distance;
• and
• a driving force transmitter configured to transmit a driving force to one of the fixing rotator and the opposed rotator, the driving force transmitter disposed in a first lateral end side of the fixing device, the first lateral end side defined by a center of the fixing rotator in the longitudinal direction of the fixing rotator, the first lateral end side where the first sealing portion is disposed, wherein the heat generating portion is symmetric with respect to the center of the fixing rotator in the longitudinal direction of the fixing rotator.