Inertial sensor

摘要

In order to provide an inertial sensor capable of suppressing a wrong diagnosis even in an adverse environment such that sudden noise occurs, an inertial sensor is provided with a movable part (105), a first detection unit (C1, C2) for detecting the amount of displacement of the movable part (105), a forced vibration means (503, C3, C4) for forcedly vibrating the movable part (105) by applying a diagnosis signal, a physical quantity calculation unit (502) for calculating the physical quantity from a detection signal from the first detection unit (C1, C2), and an abnormality determination unit (504) for determining the presence or absence of the abnormality for the physical quantity using the diagnosis signal obtained via the first detection unit (C1, C2), and is used within a vehicle, the inertial sensor further comprising a second sensor (510) mounted in the same vehicle and connected to the abnormality determination unit (504).

主权项

1. An inertial sensor, comprising:
a first substrate to be installed in a vehicle; a first cavity formed on the first substrate; a first fixed part formed in the first cavity; a first elastically deformed part formed in the cavity and connected to the fixed part; a first movable part formed in the first cavity and connected to the elastically deformed part; a first capacity sensing element which includes a first capacitative element that mutually opposes a first fixed electrode formed in the first cavity and a first movable electrode formed in the movable part and which outputs variation of capacity of the first capacitative element caused when the movable part is displaced by an external force; a first physical quantity calculation terminal connected to a first physical quantity calculating device that calculates a physical quantity of the external force based upon the variation of the capacity output from the first capacity sensing element; a forced oscillation generating device which includes a second capacitative element that mutually opposes a second fixed electrode formed in the first cavity and a second movable electrode formed in the movable part, which includes a terminal for applying a diagnostic signal between the second fixed electrode and the second movable electrode and which generates electrostatic force between the second fixed electrode and the second movable electrode by applying a diagnostic signal to the terminal for applying the diagnostic signal and forcedly oscillates them; an abnormality determination device which is indirectly connected to the first physical quantity calculation terminal and which judges whether the inertial sensor is abnormal or not based upon forced oscillation generated in the forced oscillation generating device; a second substrate to be installed in the vehicle; a second cavity formed on the second substrate; a second fixed part formed in the second cavity; a second elastically deformed part formed in the second cavity and connected to the second fixed part; a second movable part formed in the second cavity and connected to the second elastically deformed part; a second capacity sensing element which includes a third capacitative element that mutually opposes a third fixed electrode formed in the second cavity and a third movable electrode formed in the second movable part and which outputs variation of capacity of the third capacitative element caused when the second movable part is displaced by an external force; and a second physical quantity calculation terminal connected to a second physical quantity calculating device that calculates physical quantity of the external force based upon the variation of the capacity output from the second capacity sensing element, wherein: in the abnormality determination device, a result of determining abnormality is determined depending upon a value acquired from the second physical quantity calculation terminal.