FINE DIFFERENTIAL PRESSURE SENSOR

PURPOSE:To provide a high-accuracy, small-sized fine differential pressure sensor by providing a moving electrode formed at the center position of a diaphragm of which periphery section is fixed to a housing, a fixed electrode formed to face the moving electrode on the back face of a wiring board and the like. CONSTITUTION:A base plate 2 having an opening section 2a, a diaphragm 3, and a base plate carrier 4 are overlappingly fixed in, the periphery section in a housing 1 having a pressure guide port 1a at the bottom section. A circular moving electrode thin plate 5 made of a ceramic is connected at the center position of the diaphragm 3. A ceramic wiring board 6 is fixed to the carrier 4, and a fixed electrode constituted of an output electrode section and an earth electrode section is formed to face the moving electrode 5 on the back face side of the wiring board 6. When low pressure is normally guided into the pressure guide port 1a, the distance between the output electrode section and the earth electrode section is increased in response to the difference between the pressures applied to both faces of the diaphragm 3. The electrostatic capacity between the electrodes is reduced, the electrostatic capacity between the output electrode section and the earth electrode section is decreased, and the change is amplified.