Patent ID: 7832717

Claim:
A sheet post-processing apparatus comprising: a processing tray on which a sheet conveyed from an image forming apparatus is stacked; a temperature sensor provided a predetermined space apart from the processing tray; a stapler that staples trailing ends of a plurality of the sheets stacked on the processing tray; a fan that sucks and discharges warm exhaust air of the image forming apparatus; an exhaust port provided to be opposed to the fan; a housing that surrounds the processing tray, mechanical members of the sheet post-processing apparatus such as the stapler, the temperature sensor, the fan, and the exhaust port; a first duct connected to the fan to lead the warm exhaust air sucked from the image forming apparatus into the housing; a second duct provided to lead the warm exhaust air discharged into the housing by the fan or ambient Air in the housing to the fan; and a control valve that performs control to lead, when the temperature sensor measures temperature equal to or higher than proper operation temperature, the ambient Air in the housing and the warm exhaust air to discharge the ambient Air and the warm exhaust air to outside of the apparatus and lead, when the temperature sensor measures temperature lower than the proper operation temperature, the warm exhaust air into the housing.