# US 5,343,731 A · Semiconductor accelerometer

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- Number: US 5,343,731 A
- Document ID: US5343731A
- Status: Granted
- Kind: A
- Application number: 07/955,062
- Filed: 1992-10-01
- Granted: 1994-09-06
- Earliest claimed: 1991-10-02
- Assignees: NEC Corporation
- Inventors: Soichiro Miyano
- Web page: https://patentgrep.com/patent/US5343731A

## CPC

- G01P 15/12: by alteration of electrical resistance {(G01P15/0897, G01P15/105 take precedence)}
- G01P 21/00: Testing or calibrating of apparatus or devices covered by the preceding groups
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})

## Abstract

Provided is a novel semiconductor accelerometer possessing an acceleration sensing feature including gage resistors on beams and a detecting feature for abnormality of the acceleration sensing feature in which the novel structure is manifested. The detection of abnormality of the acceleration sensing feature is accomplished by comparing a voltage applied to a bridge circuit comprising the gage resistors with a predetermined reference voltage. The detecting feature essentially comprises a comparator and a generator. The comparator compares the voltage applied to the bridge circuit with a predetermined reference voltage supplied from the voltage generator. When the gage resistors has abnormality in the sensing performance, the applied voltage takes a higher voltage than that in the normal state. Therefore, the comparison of the above both voltages permits recognizing the gage resistors to have abnormality. The result of the comparison may be transmitted either through the amplifier to a common terminal to the acceleration signals or through an executive output circuit to an executive output terminal.

## Claims

### Claim 1

A semiconductor accelerometer, comprising:
a body including at least one mass supported at its opposite end by beams;
means on said beam for sensing strains of said beams, said sensing means generating a voltage corresponding to accelerations;
means for amplifying said voltage as voltage signals received from said sensing means to detect accelerations; and
means for detecting abnormalities in said sensing means by comparing a voltage applied to said sensing means with a predetermined reference voltage, wherein said amplifying means outputs detecting signals received from said detecting means to a common terminal which also outputs said voltage corresponding to accelerations.

### Claim 2 (depends on 1)

The semiconductor accelerometer as claimed in claim 1, wherein said amplifying means outputs a predetermined constant voltage to said common terminal when an abnormality in said sensing means is detected.

### Claim 3 (depends on 1)

The semiconductor accelerometer as claimed in claim 1, wherein said sensing means comprises a plurality of gage resistors forming a bridge circuit.

### Claim 4 (depends on 1)

The semiconductor accelerometer as claimed in claim 1, further comprising a circuit for supplying power to said gage resistors, said power supply circuit being connected to series to said bridge circuit.

### Claim 5 (depends on 1)

The semiconductor accelerometer as claimed in claim 1, wherein said detecting means comprises a generator for generating said reference voltage and a comparator for comparing said voltage applied to said sensing means with said reference voltage fetched from said generator.