The present invention provides a backlight device that has a heat-generating light source, such as a fluorescent tube. Icons are displayed on a display screen. The cage completely encloses the objects. When the ciphertext data is input, by the XOR circuit, the random number sequence stored in the random number sequence memory is read and the ciphertext data is decrypted into the data. The compound includes an alkali metal and an amide ligand and is a liquid at a temperature of less than about 70\xb0 C.