US 6,668,614 B2 · Capacitive type physical quantity detecting sensor for detecting physical quantity along plural axes

Abstract

A control signal generator transmits a first signal to a movable electrode and a fixed electrode to detect a change in a capacitance formed between the movable electrode and the fixed electrode during a normal physical quantity detection timing interval. Also, the control signal generator transmits a second signal to the movable electrode and the fixed electrode instead of the first signal to move the movable electrode for diagnosing a malfunction of each of a plurality of physical quantity detection portions during a self diagnosis timing interval. The control signal generator transmits the second signal to the movable electrode and the fixed electrode of each physical quantity detection portion during a different timing intervals.

Drawings

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Drawings

Claims7

Dependent claims

A capacitive type physical quantity detecting sensor comprising:

a plurality of physical quantity detection portions for detecting a physical quantity, the plurality of physical quantity detection portions respectively including:
a movable electrode that moves based on a physical quantity change;
a fixed electrode disposed to face the movable electrode;
a control signal generator for generating control signals;
a C-V converter for outputting a voltage that corresponds to a change of a capacitance formed between the movable electrode and the fixed electrode;
and
a signal processing circuit for processing the output voltage from the C-V converter and for outputting a signal corresponding to the physical quantity change;
wherein the control signal generator transmits a first signal to the movable electrode and the fixed electrode to detect the change in the capacitance formed between the movable electrode and the fixed electrode during a normal physical quantity detection timing interval, and transmits a second signal to the movable electrode and the fixed electrode to move the movable electrode for diagnosing a malfunction of each of the physical quantity detection portions in a self diagnosis timing interval,
the control signal generator transmits the second signal to the movable electrode and the fixed electrode of each physical quantity detection portion at different timing intervals.

6 more elements

A capacitive type physical quantity detecting sensor comprising:

a plurality of physical quantity detection portions for detecting a physical quantity, each of the plurality of physical quantity detection portions respectively including:
a movable electrode that moves based on a physical quantity change;
a fixed electrode disposed to face the movable electrode;
a control signal generator for generating control signals;
a C-V converter for outputting a voltage that corresponds to a change in a capacitance formed between the movable electrode and the fixed electrode;
and
a signal processing circuit for processing the output voltage from the C-V converter and for outputting a signal corresponding to the physical quantity change;
wherein the control signal generator transmits a first signal to the movable electrode and the fixed electrode to detect the change in the capacitance formed between the movable electrode and the fixed electrode during a normal physical quantity detection timing interval, and transmits a second signal to the movable electrode and the fixed electrode to move the movable electrode for diagnosing a malfunction of each of the plurality of physical quantity detection portions during a self diagnosis timing interval,
wherein a first frequency of the second signal transmitted to a first one of the plurality of quantity detection portions is different from a second frequency of the second signal transmitted to a second one of the plurality of the physical quantity detection portions.

6 more elements

Dependencies are inferred from the claim text.

Description4,653 words

Summary485 words

#The present invention relates generally to sensors, and specifically to a capacitive type physical quantity detecting sensor for detecting physical quantities along plural axes.

#JP-A-2000-81449 (USP 6,257,061) discloses a capacitive type physical quantity detecting sensor with a malfunction self diagnosis function. The capacitive type physical quantity detecting sensor diagnoses malfunctions itself by using the resonance of the sensor elements generated based on the frequency (hereinafter referred to as self diagnosis frequency) of an applied electrical voltage.

#However, if the above mentioned technology is applied to a capacitive type physical quantity detecting sensor for detecting physical quantities along two directional axes, since the self diagnosis frequency is used to create resonance of the sensor elements, another resonance is simultaneously generated between both sensor elements. That is, the sensor elements interfere with each other during self diagnosis so that a resonance, which is different from the resonance being used for the diagnosis, is generated. Accordingly, an accurate sensor output that is expected during self diagnosis cannot be obtained.

Brief description of the drawings7 figures

#Other objects, features and advantages of the present invention will be understood more fully from the following detailed description made with reference to the accompanying drawings in which:

#FIG. 1 shows an oblique perspective cross sectional view of an acceleration sensor according to a first embodiment of the present invention;

#FIG. 2 shows an electrical circuit of the acceleration sensor according to the first embodiment;

Detailed description3,970 words

#The present invention will be described further with reference to various embodiments shown in the drawings.

#(First embodiment)

#A capacitive type acceleration sensor is described as a capacitive type physical quantity detecting sensor. Referring to FIG. 1, the acceleration sensor includes a first detection portion for detecting acceleration along the X axis and a second detection portion for detecting acceleration along the Y axis. The acceleration sensor is accommodated in a vehicle so that the X axis corresponds to a font/rear direction of the vehicle and the Y axis corresponds to a left/right direction.

Facts

Application

10/234,142Filed 5 Sep 2002

Priority

JP 2001-31846716 Oct 2001

Published

US 2003/0070484 A117 Apr 2003

Granted

30 Dec 2003

Term ended

5 Sep 2022

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification6 codes

G01P 15/18
Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration: in two or more dimensions
G01D 5/2417
By relative movement of capacitor electrodes: by varying separation
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

Capacitive type physical quantity detecting sensor for detecting physical quantity along plural axes

Life of this patent

Capacitive type physical quantity detecting sensor for detecting physical quantity along plural axes

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims7

Description4,653 words

Drawings

Classification6 codes

Life of this patent

Description4,653 words