US 8,427,177 B2Granted

Capacitance sensor

AssigneeHitachi Automotive Systems, Ltd.

InventorsHeewon Jeong, Kiyoko Yamanaka, Yasushi Goto, Toshiaki Nakamura, Masahide Hayashi

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Abstract

A technique in which a false detection and a wrong diagnosis can be suppressed in a capacitance sensor represented by an acceleration sensor is provided. A first capacitative element and a second capacitative element, which configure a capacitance detection unit, and a third capacitative element and a fourth capacitative element, which configure a forced oscillation generation unit, are electrically separated from each other. That is, the diagnosis movable electrode that configures the third capacitative element and the fourth capacitative element is formed integrally with the movable part. On the other hand, the diagnosis fixed electrode and the diagnosis fixed electrode are electrically separated from the detection fixed electrode and the detection fixed electrode.

Claims21

Dependent claims

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.

8 more elements

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 displacement 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, a first diagnostic signal supply terminal for supplying a first diagnostic signal between the second fixed electrode and the second movable electrode, and a second diagnostic signal supply terminal for supplying a second diagnostic signal between the second fixed electrode and the second movable electrode, and when operation starts, supplies the first diagnostic signal to the first diagnostic signal supply terminal to displace the movable part in a first direction, and supplies the second diagnostic signal to the second diagnostic signal supply terminal to displace the movable part in a second direction opposite to the first direction;
and
(i) the physical quantity calculation terminal that is connected indirectly to an abnormality determination unit that determines whether there is an abnormality in the capacitance sensor, or not, on the basis of the forced displacement generated in the forced displacement generation unit,
wherein the first capacitative element included in the capacitance detection unit and the second capacitative element included in the forced displacement generation unit are separated from each other.

8 more elements

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 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 displacement 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, a first diagnostic signal supply terminal for supplying a first diagnostic signal between the second fixed electrode and the second movable electrode, and a second diagnostic signal supply terminal for supplying a second diagnostic signal between the second fixed electrode and the second movable electrode, and when operation starts, supplies the first diagnostic signal to the first diagnostic signal supply terminal to displace the movable part in a first direction, and supplies the second diagnostic signal to the second diagnostic signal supply terminal to displace the movable part in a second direction opposite to the first direction;
and
(i) an abnormality determination unit that determines whether there is an abnormality in the capacitance sensor, or not, on the basis of the forced displacement generated in the forced displacement generation unit,
wherein the first capacitative element included in the capacitance detection unit and the second capacitative element included in the forced displacement generation unit are separated from each other.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/912,580Filed 26 Oct 2010
Priority: JP 2009-24942429 Oct 2009
Published: US 2011/0100126 A15 May 2011
Granted: 23 Apr 2013
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01P 21/00
Testing or calibrating of apparatus or devices covered by the preceding groups
G01C 19/5719
Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces: using planar vibrating masses driven…
G01P 15/125
With conversion into electric or magnetic values: by capacitive pick-up
G01P 2015/0814
For one single degree of freedom of movement of the mass: for translational movement of the mass, e.g. shuttle type