Fixing device and image forming apparatus

A fixing device comprising:

• a fixing rotator rotatable in a predetermined direction of rotation;
• a pressure rotator to press against the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator;
• a primary heater disposed opposite the fixing rotator to heat a circumferential span of the fixing rotator other than the fixing nip;
• and
• a secondary heater disposed outboard from the primary heater in an axial direction of the fixing rotator to heat the fixing rotator at the fixing nip,
• the primary heater and the secondary heater to heat a bi-heating span of the fixing rotator in the axial direction of the fixing rotator,
• the secondary heater to heat a mono-heating span of the fixing rotator in the axial direction of the fixing rotator and generate a decreased amount of heat to be conducted to the bi-heating span of the fixing rotator, the decreased amount of heat being smaller than an increased amount of heat to be conducted to the mono-heating span of the fixing rotator that is heated solely by the secondary heater of the primary heater and the secondary heater,
• wherein the fixing rotator includes a flexible endless belt,
• wherein the fixing device further comprises a nip formation pad to press against the pressure rotator via the endless belt to form the fixing nip,
• wherein the secondary heater is leveled with the nip formation pad to define a substantially identical plane.

An image forming apparatus comprising:

• an image bearer to bear a toner image;
• a fixing rotator disposed downstream from the image bearer in a recording medium conveyance direction and rotatable in a predetermined direction of rotation;
• a pressure rotator to press against the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator;
• a primary heater disposed opposite the fixing rotator to heat a circumferential span of the fixing rotator other than the fixing nip;
• a secondary heater disposed outboard from the primary heater in an axial direction of the fixing rotator to heat the fixing rotator at the fixing nip;
• and
• an electric circuit electrically connected to the primary heater and the secondary heater to energize the primary heater and the secondary heater,
• the primary heater and the secondary heater to heat a bi-heating span of the fixing rotator in the axial direction of the fixing rotator,
• the secondary heater to heat a mono-heating span of the fixing rotator in the axial direction of the fixing rotator and generate a decreased amount of heat to be conducted to the bi-heating span of the fixing rotator, the decreased amount of heat being smaller than an increased amount of heat to be conducted to the mono-heating span of the fixing rotator that is heated solely by the secondary heater of the primary heater and the secondary heater,
• wherein the fixing rotator includes a flexible endless belt,
• wherein the fixing device further comprises a nip formation pad to press against the pressure rotator via the endless belt to form the fixing nip,
• wherein the secondary heater is leveled with the nip formation pad to define a substantially identical plane.