Patent ID: 8427177
Filing Date: 2013-04-23
Classification: G01C,G01P

Abstract:
1. A capacitance sensor comprising: (a) a substrate; (b) a cavity part that is formed in the substrate; (c) a fixed part that is formed within the cavity part; (d) an elastic deformation part that is formed within the cavity part and connected to the fixed part; (e) a movable part that is formed within the cavity part, and connected to the elastic deformation part; (f) a capacitance detection unit that includes a first capacitative element having a first fixed electrode formed within the cavity part, and a first movable electrode formed in the movable part so as to face each other, and outputs a capacitance change of the first capacitative element, which is developed by displacing the movable part; (g) a physical quantity calculation terminal that is connected to a physical quantity calculation section which finds a physical quantity of an external force on the basis of the capacitance change which is outputted from the capacitance detection unit; (h) a forced oscillation generation unit that includes a second capacitative element having a second fixed electrode formed within the cavity part, and a second movable electrode formed in the movable part so as to face each other, and a diagnostic signal supply terminal for supplying a diagnostic signal between the second fixed electrode and the second movable electrode, and supplies the diagnostic signal to the diagnostic signal supply terminal to develop an electrostatic force between the second fixed electrode and the second movable electrode for generating forced oscillation; and (i) the physical quantity calculation terminal that is connected indirectly to an abnormality determination unit which determines whether there is an abnormality in the capacitance sensor, or not, on the basis of the forced oscillation generated in the forced oscillation generation unit, wherein the first capacitative element included in the capacitance detection unit and the second capacitative element included in the forced oscillation generation unit are separated from each other.