| 摘要 |
PURPOSE:To eliminate erroneous detection of a pressure and further to enable prevention of the strain of a diaphragm part due to a thermal expansion difference by a construction wherein an outer thickness part on the pressure receiving side facing a vacant space formed in one end part of a ceramic layer is used as a diaphragm part. CONSTITUTION:When a sensor S is disposed with the upper end thereof held and with the lower end exposed in the necessary ambience of a pressure to be detected, a diaphragm 5 is strained in the shape of a depression onto the vacant space 4 side by the pressure to be detected. Thereby a movable electrode 7 is made to approach a detecting electrode 8. Therefore the mutual distance of separation between them becomes small and an electrostatic capacity between the electrodes 7 and 8 which is detected at a conductive end 10b increases. On the other hand, a reference electrode 9 faces the peripheral edge part of the movable electrode 7 in which no strain is generated when the pressure to be detected acts thereon, and even when the depression strain occurs in the diaphragm 5, a distance between the electrodes 7 and 9 does not change and, consequently, the electrostatic capacity between them does not change. By using the electrostatic capacity between the electrodes 7 and 9 as a reference, the amount of a change in the electrostatic capacity between the electrodes 7 and 8 can be detected and the pressure to be detected can be detected correctly. |
