To provide a small-sized acceleration sensor having a large absolute value of electrostatic capacity and a small detection error by providing a hole section on a moving electrode in the direction perpendicular to the displacing direction, and arranging fixed electrodes in it in the direction perpendicular to the displacing direction of the moving electrode.
A first fixed electrode 3, a second fixed electrode 4, and a moving electrode 5 are stored in the sealed space formed with an upper base plate 1A, a frame body 2, and a lower base plate 1B, and these electrodes are made of an SOI wafer to widen their electrode areas. Acceleration is obtained from the difference between the electrostatic capacity C1 of a first capacitor formed with the electrodes 5, 3 and the electrostatic capacity C2 of a second capacitor formed with the electrodes 5, 4, and the change of the electrostatic capacity caused by the twist or the like of the moving electrode 5 is offset. A conductive thin film is formed on the upper base plate 1A, many electrodes are electrically integrated, and a stopper regulating the moving range of the moving electrode 5 is provided in a sealed container or thin insulating films are provided on the surfaces of the electrodes as short circuit preventing measures.
KANAMARU MASATOSHI
SUZUKI KIYOMITSU
HORIE JUNICHI
