The present embodiments provide methods, apparatuses, and systems for use in maintaining data quality upon conversion to a different data format. The contactless charging method comprises: a step of detecting a charging frequency when a charging operation is performed by enabling the primary coil 11 to get close to the secondary coil 21; and a step of outputting the charging efficiency of the battery 30 acquired from the detected charging frequency such that a user may know the charging efficiency. A line-shaped source of stimulation radiation and a line-shaped light detector are mounted to the supporting structure. The WDM light is amplified in a wavelength band divided into a plurality of individual wavelength bands. The keyboard is constructed in two portions which may be pivoted relative to the body of the device between two positions, one in which the keyboard is hidden and the keypad of the device is exposed for normal use and a second in which the two portions of the keyboard are positioned on opposite sides of the screen of the device to allow holding with both hands and operation with the thumb.