Patent ID: 7873293

Claim:
An image heating apparatus comprising: a heater including a substrate, a heat generation resistive member formed on the substrate, and a first electrode and a second electrode for feeding power to the heat generating resistive member; a backup member that forms a nip portion together with the heater; and a control unit that controls power to be fed to the heat generation resistive member so that temperature of the heater maintains a set temperature during an image heating process wherein the image heating apparatus heats an image on a recording material at the nip portion; wherein each of the first electrode and the second electrode includes a first area contacting with a feed power connector and a second area on an electrically opposite side of the first area; the second area is disposed along a longitudinal direction of the substrate; the heat generation resistive member is disposed so as to electrically connect the second area of the first electrode with the second area of the second electrode; the heat generation resistive member is formed by sputtering or vapor-depositing, a part of the second area of the first electrode electrically closest to the first area is disposed on one end portion side in the longitudinal direction of the substrate; a part of the second area of the second electrode which is electrically closest to the first area is disposed on another end portion side in the longitudinal direction of the substrate; a length of the second area of each of the first electrode and the second electrode in the longitudinal direction of the substrate is denoted by L 1 [m] and a cross-section of the second area cut along a short side direction of the substrate is denoted by S 1 [m 2 ]; a length of the heat generation resistive member in the short side direction is denoted by L 2 [m] and a cross-section of the heat generation resistive member cut along the longitudinal direction is denoted by S 2 [m 2 ]; and a volume resistance value of the second area of each of the first electrode and the second electrode at the set temperature is denoted by A 1 [Ω·m] and a volume resistance value of the heat generation resistive member at the set temperature is denoted by A 2 [Ω·m], A 1 ≦A 2 ×S 1 ×L 2 /(29.4×S 2 ×L 1 ) is satisfied.