An LED indicator device is mounted in an AC power plug or socket and electrically connected in parallel with an AC power source. The blocking elements are made of a first shutter and a second shutter below the first in the passage; and the first and second shutters are mechanically connected so that the first shutter closes before the second one. The gas generator and the air bag are connected by a gas distributing duct which extends at least partially at an angle with respect to the main inflating direction of the air bag. The control can alter conditions such as clock frequency, stopping use of application software, interrupting OS functionality, removing power from components and so forth. The brightness difference exhibited on the display screen is also reduced, so that a brightness uniformity is achieved.