A cold cathode discharge lamp includes: a transparent hollow housing; a fluorescent film formed on inner surfaces of the hollow housing; a pair of cold cathodes that are located in the hollow housing; and a discharge gas that contains hydrogen gas sealed within the hollow housing. The user may access a server over a network and specify a desired task, e. Furthermore, there is provided a potential difference source for applying a potential difference between the sensor element and the lubricant. Further realism is provided by changing the way the blocks fall upon a collapse of a building. Alternatively, the mobile storage devices may also be issued with the trees already created so that a purchaser does not have to go through the trouble of creating the trees. According to the present invention, in order not to display the display defects that take place when a light from a light source transmits a liquid crystal panel having the point defects, means for correcting the display defects is provided on the liquid crystal panel side of a screen.