Image forming apparatus with overheat preventive device

摘要

An image forming apparatus includes a heater for heating a recording material for fixing a transferred toner image to the recording material at a transfer portion. A fixing unit includes at least one overheat preventive device for preventing the heater from overheating. A recording material sensor detects a front end timing of the recording material. A part of all of the at least one overheat preventive device is placed on a plane perpendicular to a conveyance surface of the recording material and passing the recording material sensor.