Apparatus for detecting a physical quantity acting as an external force and method for testing and manufacturing the apparatus

• US 20050199434A1
• Filed: 01/25/2005
• Published: 09/15/2005
• Est. Priority Date: 12/28/1989
• Status: Active Grant

• Current Assignee: Wacoh Company
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Granted Patent: US 7,231,802 B2
• Time in Patent Office: Days
• US Class Current: 180/282
• CPC Class Codes: G01L 1/148 using semiconductive material, e.g. silicon
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 25/00 Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
• CPC Class Codes: G01L 5/162 of piezoresistors
• CPC Class Codes: G01P 1/023 for acceleration measuring devices
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

A sensor comprises a semiconductor pellet (10) including a working portion (11) adapted to undergo action of a force, a fixed portion (13) fixed on the sensor body, and a flexible portion (13) having flexibility formed therebetween, a working body (20) for transmitting an exterted force to the working portion, and detector means (60-63) for transforming a mechanical deformation produced in the semiconductor pellet to an electric signal to thereby detect a force exerted on the working body as an electric signal. A signal processing circuit is applied to the sensor. This circuit uses analog multipliers (101-109) and analog adders/subtracters (111-113), and has a function to cancel interference produced in different directions. Within the sensor, two portions (E3, E4-E8) located at positions opposite to each other and producing a displacement therebetween by action of a force are determined. By exerting a coulomb force between both the portions, the test of the sensor is carried out. Further, a pedestal (21, 22) is provided around the working body (20). The working body and the pedestal are located with a predetermined gap or spacing therebetween. A displacement of the working body is caused to limitatively fall within a predetermined range corresponding to the spacing. The working body and the pedestal are provided by cutting a same common substrate (350, 350′).

Claims

1. A method of testing an acceleration sensor,

said acceleration sensor comprising:

a substrate arranged along a XY-plane of an XYZ three-dimensional coordinate system;

a working body receiving a force and located adjacent to said substrate with a predetermined distance;

a flexible member made of silicon supporting said working body at a periphery thereof so that said working body is suspended and spatial deviation of said working body is produced by applying said force thereto;

a fixing member fixing said flexible member to said substrate; and

a transducer for transforming said spatial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of;

causing spatial deviation of said working body in an X-axis direction of said XYZ three-dimensional coordinate system by applying Coulomb force;

detecting an electric signal transformed by said transducer while said spatial deviation is caused by applying said Coulomb force; and

testing an operation of said acceleration sensor with respect to said X-axis direction based on a relationship between said applied Coulomb force and said detected electric signal.

2. A method of testing an acceleration sensor,

said acceleration sensor comprising:

a substrate arranged along an XY-plane of an XYZ three-dimensional coordinate system;

a working body receiving a force and located adjacent to said substrate with a predetermined distance;

a flexible member made of silicon supporting said working body at a periphery thereof so that said working body is suspended and spatial deviation of said working body is produced by applying said force thereto;

a fixing member fixing said flexible member to said substrate; and

a transducer for transforming said spatial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of;

causing spatial deviation of said working body in a Z-axis direction of said XYZ three-dimensional coordinate system by applying Coulomb force;

detecting an electric signal transformed by said transducer while said spatial deviation is caused by applying said Coulomb force; and

testing an operation of said acceleration sensor with respect to said Z-axis direction based on a relationship between said applied Coulomb force and said detected electric signal.

3. A method of testing an acceleration sensor,

said acceleration sensor comprising:

a substrate arranged along an XY-plane of an XYZ three-dimensional coordinate system;

a working body receiving a force and located adjacent to said substrate with a predetermined distance;

a flexible member made of silicon supporting said working body at a periphery thereof so that said working body is suspended and spatial deviation of said working body is produced by applying said force thereto;

a fixing member fixing said flexible member to said substrate; and

a transducer for transforming said spatial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of

causing first spatial deviation of said working body in an X-axis direction of said XYZ three-dimensional coordinate by applying a first Coulomb force system;

detecting a first electric signal transformed by said transducer while said first spatial deviation is caused by applying said first Coulomb force;

testing a first operation of said acceleration sensor with respect to said X-axis direction based on a relationship between said applied first Coulomb force and said detected first electric signal;

causing second spatial deviation of said working body in a Z-axis direction of said XYZ three-dimensional coordinate system by applying a second Coulomb force;

detecting a second electric signal transformed by said transducer while said second spatial deviation is caused by applying said second Coulomb force; and

testing a second operation of said acceleration sensor with respect to said Z-axis direction based on a relationship between said applied second Coulomb force and said detected second electric signal.

4. A method of testing an acceleration sensor,

said acceleration sensor comprising:

a substrate arranged along an XY-plane of an XYZ three-dimensional coordinate system;

a working body receiving a force and located adjacent to said substrate with a predetermined distance;

a flexible member made of silicon supporting said working body at a periphery thereof so that said working body is suspended and spatial deviation of said working body is produced by applying said force thereto;

a fixing member fixing said flexible member to said substrate; and

a transducer for transforming said spatial deviation into an electric signal that indicates direction and a magnitude of said force;

said method comprising the steps of;

causing first spatial deviation of said working body in an X-axis direction of said XYZ three-dimensional coordinate system by applying a first Coulomb force;

detecting a first electric signal transformed by said transducer while said first spatial deviation is caused by applying said first Coulomb force;

testing a first operation of said acceleration sensor with respect to said X-axis direction based on a relationship between said applied first Coulomb force and said detected first electric signal;

causing second spatial deviation of said working body in a Y-axis direction of said XYZ three-dimensional coordinate system by applying a second Coulomb force;

detecting a second electric signal transformed by said transducer while said second spatial deviation is caused by applying said second Coulomb force; and

testing a second operation of said acceleration sensor with respect to said Y-axis direction based on a relationship between said applied second Coulomb force and said detected second electric signal.

5. A method of testing an acceleration sensor,

said acceleration sensor comprising:

a substrate arranged along an XY-plane of an XYZ three-dimensional coordinate system;

a working body receiving a force and located adjacent to said substrate with a predetermined distance;

a flexible member made of silicon supporting said working body at a periphery thereof so that said working body is suspended and spatial deviation of said working body is produced by applying said force thereto;

a fixing member fixing said flexible member to said substrate; and

a transducer for transforming said spatial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of;

causing first spatial deviation of said working body in an X-axis direction of said XYZ three-dimensional coordinate system by applying a first Coulomb force;

detecting a first electric signal transformed by said transducer while said first spatial deviation is caused by applying said first Coulomb force;

testing a first operation of said acceleration sensor with respect to said X-axis direction based on a relationship between said applied first Coulomb force and said detected first electric signal;

causing second spatial deviation of said working body in a Y-axis direction of said XYZ three-dimensional coordinate system by applying a second Coulomb force;

detecting a second electric signal transformed by said transducer while said second spatial deviation is caused by applying said second Coulomb force;

testing a second operation of said acceleration sensor with respect to said Y-axis direction based on a relationship between said applied second Coulomb force and said detected second electric signal;

causing third spatial deviation of said working body in a Z-axis direction of said XYZ three-dimensional coordinate system by applying a third Coulomb force;

detecting a third electric signal transformed by said transducer while said third spatial deviation is caused by applying said third Coulomb force; and

testing a third operation of said acceleration sensor with respect to said Z-axis direction based on a relationship between said applied third Coulomb force and said detected third electric signal.