| 摘要 |
The invention is to provide an image heating apparatus capable of preventing an excessive temperature increase in a sheet non-passing area and a heater for use in such apparatus, and the heater for use in the image heating apparatus of the invention is constructed by including: a substrate; a heat generating resistor formed on the substrate; and first and second electrodes for supplying an electric power to the heat generating resistor; wherein each of the first and second electrodes has a first area to be contacted with a power supplying connector and a second area provided at an end portion electrically opposite to the first area, the second areas are provided along a longitudinal direction of the substrate, and the heat generating resistor is so provided as to electrically connect the second area of the first electrode and the second area of the second electrode; wherein, within the second area of the first electrode, a portion electrically closest to the first area of the first electrode is provided in the vicinity of an end portion of the substrate in the longitudinal direction thereof, and within the second area of the second electrode, a portion electrically closest to the first area of the second electrode is provided in the vicinity of the other end portion of the substrate in the longitudinal direction thereof; and wherein, when the heater is at a set temperature for an image heating operation in the image heating apparatus, a resistance value Rc of the second area of either of the first and second electrodes and a resistance value Rt between a portion within the second area of the first electrode electrically closest to the first area of the first electrode and a portion within the second area of the second electrode electrically closest to the first area of the second electrode satisfy a relation: <?in-line-formulae description="In-line Formulae" end="lead"?>Rc/Rt<= 1/30. <?in-line-formulae description="In-line Formulae" end="tail"?> |
