US Patent 7154452 Electronic paper, electronic paperfile and electronic pen

The invention has an object to provide the electronic paper file, which an electronic paper can be attached to or detached from by providing a connecting terminal including the physical or electrical connecting function to both the electronic paper and the main unit. Since the display data is to be displayed on the nonvolatile display medium fitted to the display of the electronic paper, the electronic paper detached from the main unit can retain the display content. Since the connecting terminal fitted to the main unit is fixed to the rotatable rotatable axis, it is possible to retain the desired page with keeping double-pages spread.