Image forming apparatus operable in horizontal and vertical installations

摘要

Disclosed is an image forming apparatus for forming a toner image on a sheet both in a horizonal installation and in a vertical installation of the apparatus. The image forming apparatus is designed so that an air flow from a thermal fixing unit exerts no influence on an image forming operation of a photosensitive body and a temperature detection operation of the thermal fixing unit even when installed horizontally or vertically. This image forming apparatus therefore includes an exhaust duct for guiding a gas of an interior of the thermal fixing unit in an upper oblique direction from the thermal fixing unit to exhaust the interior Of the thermal fixing unit. The air flow from the thermal fixing unit does not therefore influence an image formation on the photosensitive body even when the apparatus is installed horizontally or vertically. This image forming apparatus also includes a temperature detector provided obliquely to a heat roller of the thermal fixing unit. The image forming apparatus further includes a plurality of temperature detectors each provided in a different position with respect to the heat roller of the thermal fixing unit. The image forming apparatus still further includes a temperature detector for detecting a temperature of the heat roller and a control circuit for controlling a fixing temperature of the heat roller by comparing a set temperature corresponding to an installing direction of the apparatus with a temperature detected by the temperature detector. The temperature of the heat roller can be therefore accurately controlled irrespective of the installing direction of the apparatus.