When a display language is different from an OCR language, which is used for document name OCR, the name of a document to be sent may not be correctly displayed on a screen. The monitor may be used to determine a state of the computer for compliance to a set of conditions. To achieve the first object, the present invention sets the amount of xenon in the discharge gas to the range of 10% by volume to less than 100% by volume, and sets the charging pressure for the discharge gas to the range of 500 to 760 Torr which is higher than conventional charging pressures.