# US 5,708,207 A · Semiconductor acceleration sensor

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- Number: US 5,708,207 A
- Document ID: US5708207A
- Status: Granted
- Kind: A
- Application number: 08/695,879
- Filed: 1996-08-12
- Granted: 1998-01-13
- Earliest claimed: 1995-02-07
- Assignees: Mitsubishi Denki Kabushiki Kaisha
- Inventors: Teruaki Nagahara; Masahiro Yamamoto
- Web page: https://patentgrep.com/patent/US5708207A

## CPC

- G01P 15/123: {by piezo-resistive elements, e.g. semiconductor strain gauges}
- G01P 15/18: in two or more dimensions
- 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

A semiconductor acceleration sensor for detecting accelerations applied in two orthogonal directions includes a semiconductor body having a peripheral frame, a central weight disposed within the peripheral frame, and first and second beams extending from and connecting the peripheral frame and the weight. At least four piezoresistors are disposed on each of the first and second beams and are electrically connected in first and second bridge circuits. Each bridge circuit includes two piezoresistors from each of the two beams so that accelerations applied perpendicular and parallel to the semiconductor body can be individually detected with a single semiconductor acceleration sensor.

## Claims

### Claim 1

A semiconductor acceleration sensor comprising:
a semiconductor body including:
a peripheral frame;
a central weight disposed within the peripheral frame; and
first and second diametrically opposite beams extending from and connecting the peripheral frame and the weight, the first and second beams being thinner than the peripheral frame and the weight, the peripheral frame, the first and second beams, and the weight having respective front surfaces that are all coplanar;
first, second, third, and fourth piezoresistors disposed on the front surface of the first beams; and
fifth, sixth, seventh, and eighth piezoresistors disposed on the front surface of the second beam wherein the first, second, third, fourth, fifth, sixth, seventh, and eighth piezoresistors are all parallel to each other and the first, second, fifth, and sixth piezoresistors are electrically connected in a first bridge circuit and the third, fourth, seventh, and eighth piezoresistors are electrically connected in a second bridge circuit whereby accelerations applied to the semiconductor body parallel to the front surface of the weight and perpendicular to the front surface of the weight can be individually detected through the first and second bridge circuits, respectively.

### Claim 2 (depends on 1)

The semiconductor acceleration sensor of claim 1 wherein the first, second, third, and fourth piezoresistors are arranged on the first beam in a rectangular array and the fifth, sixth, seventh, and eighth piezoresistors are arranged on the second beam in a linear array.

### Claim 3 (depends on 1)

The semiconductor acceleration sensor of claim 1 wherein the fifth, sixth, seventh, and eighth piezoresistors are located adjacent the peripheral frame and spaced from the weight.

### Claim 4 (depends on 1)

The semiconductor acceleration sensor of claim 1 wherein the first, second, third, and fourth piezoresistors are arranged on the first beam in a linear array and the fifth, sixth, seventh, and eighth piezoresistors are arranged on the second beam in a rectangular array.

### Claim 5 (depends on 1)

The semiconductor acceleration sensor of claim 1 wherein the first, second, third, and fourth piezoresistors are located adjacent the weight and spaced from the peripheral frame.

### Claim 6 (depends on 1)

The semiconductor acceleration sensor of claim 1 including ninth and tenth piezoresistors disposed on the first beam and eleventh and twelfth piezoresistors disposed on the second beam wherein the ninth, tenth, eleventh, and twelfth piezoresistors are respectively connected in series with the fifth, sixth, first, and second piezoresistors in the first bridge circuit whereby sensitivity to detected acceleration is increased.