Heater unit, fixing device, and image forming apparatus

A fixing device, comprising:

• a cylindrical fixing belt extending longitudinally in a first direction;
• and
• a heater unit within an interior region formed by the cylindrical fixing belt and positioned to heat an inner surface of the cylindrical fixing belt, wherein
• the heater unit includes:
• a substrate;
• a first heating element on a first side of the substrate;
• a second heating element on a second side of the substrate, the second side being opposite the first side;
• a first wiring on the first side of the substrate and connected to the first heating element;
• a first electrode on the first side of the substrate and connected to the first heating element;
• a second wiring on the second side of the substrate and connected to the second heating element;
• and
• a second electrode on the second side of the substrate and connected to the second heating element via the second wiring, and
• a portion of the second heating element overlaps a first portion of the first heating element.

An image forming apparatus, comprising:

• an image forming unit configured to form a toner image on a sheet;
• and
• a fixing device configured to heat the toner image on the sheet to fix the toner image to the sheet, wherein
• the fixing device includes a heater unit,
• the heater unit includes:
• a substrate;
• a first heating element on a first side of the substrate;
• a second heating element on a second side of the substrate, the second side being opposite the first side;
• a first wiring on the first side of the substrate and connected to the first heating element;
• a first electrode on the first side of the substrate and connected to the first heating element;
• a second wiring on the second side of the substrate and connected to the second heating element;
• and
• a second electrode on the second side of the substrate and connected to the second heating element via the second wiring, and
• a portion of the second heating element overlaps a first portion of the first heating element.