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

• US 6,474,133 B1
• Filed: 12/15/1993
• Issued: 11/05/2002
• Est. Priority Date: 12/28/1989
• Status: Expired due to Term

• Current Assignee: Kazuhiro Okada
• Original Assignee: Kazuhiro Okada
• Inventors: Okada, Kazuhiro
• Primary Examiner(s): Raevis, Robert R
• Application Number:
  US08/168,024
• Time in Patent Office: 3,247 Days
• Field of Search: 73/10.8, 73/10.9, 73/11.5, 73/15--, 73/13.7, 73/13.8, 310/309
• US Class Current: 73/1.38
• 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 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
• CPC Class Codes: Y10T 29/49103 Strain gauge making

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 exerted 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/subtractors (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 a sensor, said sensor comprising:

a strain generative body including a working portion adapted to undergo action of a force, a fixed portion fixed to a sensor body and a flexible portion having flexibility, said flexible portion surrounding said working portion and said fixed portion surrounding said flexible portion,

a working body fixed to said working portion on a lower surface of said strain generative body, said working body being suspended from the fixed portion with three-dimensional freedom so that a spacial deviation of said working body is produced by exerting a force thereto,

detector means for transforming said spacial deviation to an electric signal which indicates a direction and a magnitude of the exerted force,

wherein said method comprises the steps of;

defining an XYZ three-dimensional coordinate system so that an XY-plane extends along an upper surface of said strain generative body and an origin locates on said working portion,

preparing a first electrode and a second electrode on the upper surface of said strain generative body, said first electrode being located on an upper surface of said flexible portion in a positive area of the X-axis and said second electrode being located on the upper surface of said flexible portion in a negative area of the X-axis,

preparing a first opposite electrode facing said first electrode with a distance and a second opposite electrode facing said second electrode with a distance, said first opposite electrode and said second opposite electrode being fixed to the sensor body,

producing a spacial deviation along the X-axis of said working body by applying a first voltage between said first electrode and said first opposite electrode and applying a second voltage between said second electrode and said second opposite electrode so that a repulsive force is produced between a pair of electrodes and an attractive force is produced between another pair of electrodes on the basis of coulomb force, and

detecting an electric signal transformed by said detector means while said spacial deviation is produced, thus to test a detecting function along the X-axis of said sensor based on a relationship between the detected electric signal and the applied voltages.

2. A method of testing a sensor as set forth in claim 1, wherein the method further comprises the steps of:

preparing a third electrode and a fourth electrode on the upper surface of the strain generative body, said third electrode being located on the upper surface of the flexible portion in a positive area of the Y-axis and said fourth electrode being located on the upper surface of the flexible portion in a negative area of the Y-axis,

preparing a third opposite electrode facing said third electrode with a distance and a fourth opposite electrode facing said fourth electrode with a distance, said third opposite electrode and said fourth opposite electrode being fixed to the sensor body,

producing a spacial deviation along the Y-axis of the working body by applying a third voltage between said third electrode and said third opposite electrode and applying a fourth voltage between said fourth electrode and said fourth opposite electrode so that a repulsive force is produced between a pair of electrodes and an attractive force is produced between another pair of electrodes on the basis of coulomb force, and

detecting an electric signal transformed by said detector means while said spacial deviation is produced, thus to test a detecting function along the Y-axis of said sensor based on a relationship between the detected electric signal and the applied voltages.

3. A method of testing a sensor as set forth in claim 2, wherein the method further comprises the steps of:

producing a spacial deviation along the Z-axis of said working body by applying a first voltage between the first electrode and the first opposite electrode, applying a second voltage between the second electrode and the second opposite electrode, applying a third voltage between the third electrode and the third opposite electrode and applying a fourth voltage between the fourth electrode and the fourth opposite electrode so that a first coulomb force is produced between the first electrode and the first opposite electrode, a second coulomb force is produced between the second electrode and the second opposite electrode, a third coulomb force is produced between the third electrode and the third opposite electrode and a fourth coulomb force is produced between the fourth electrode and the fourth opposite electrode, said first, second, third and fourth coulomb force having a same polarity, and

detecting an electric signal transformed by said detector means while said spacial deviation is produced, thus to test a detecting function along the Z-axis of said sensor based on a relationship between the detected electric signal and the applied voltages.

4. A method of testing a sensor as set forth in claim 2,

wherein polarities of the first, second, third and fourth voltages are varied with time.

5. A method of testing a sensor as set forth in claim 4, wherein the method further comprises the further steps of:

applying another voltage between said first electrode and said first opposite electrode and applying another voltage between said second electrode and said second opposite electrode so that another attractive-polarity coulomb force is produced between one of said first and first opposite or second and second opposite electrodes and another attractive-polarity coulomb force is produced between the other thereof, said other coulomb forces constituting another said force for producing another spacial deviation of said working body;

detecting another electric signal transformed by said detector means while other said other spacial deviation is produced; and

testing said detecting along said Z-axis from a relationship between said other electric signal and said other applied voltages.

6. A method of testing a sensor as set forth in claim 1, wherein the method further comprises the steps of:

producing a spacial deviation along the Z-axis of the working body by applying a first voltage between the first electrode and the first opposite electrode and applying a second voltage between the second electrode and the second opposite electrode so that a first coulomb force is produced between the second electrode and the first opposite electrode and a second coulomb force is produced between the second electrode and the second opposite electrode, said first coulomb force and said second coulomb force having a same polarity, and

detecting an electric signal transformed by said detector means while said spacial deviation is produced, thus to test a detecting function along the Z-axis of said sensor based on a relationship between the detected electric signal and the applied voltages.

7. A method of testing a sensor as set forth in claim 1,

wherein polarities of the first voltage and the second voltage are varied with time.

8. A method of testing a sensor, said sensor comprising:

a sensor body;

a strain generative body including a working potion for receiving a force, a flexible portion about said working portion and having flexibility to said force, and a fixed portion about said flexible portion and fixed to said sensor body;

a working body fixed to said working portion on a lower surface of said strain generative body, whereby said working body is suspended from said sensor body with three-dimensional freedom so that spacial deviation of said working body is produced by applying said force thereto; and

detector means for transforming said spacial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of;

defining an XYZ three-dimensional coordinate system so that an XY-plane thereof is on an upper surface of said strain generative body and an origin is located on said working portion thereof;

providing a first electrode and a second electrode on said upper surface of said strain generative body on said flexible portion thereof, said first electrode being located in a positive area of said X-axis and said second electrode being located in a negative area of the X-axis;

providing on said sensor body a first opposite electrode facing said first electrode from a distance and a second opposite electrode facing said second electrode from a distance;

applying a first voltage between said first electrode and said first opposite electrode and applying a second voltage between said second electrode and said second opposite electrode so that a first repulsive-polarity coulomb force is produced between one of said first and first opposite or second and second opposite electrodes and a second attractive-polarity coulomb force is produced between the other thereof, said first and second coulomb forces constituting said force for producing said spacial deviation of said working body;

detecting an electric signal transformed by said detector means while said spacial deviation is produced; and

testing said detecting along said X-axis from relationship between said electric signal and said first and second applied voltages.

9. A method of testing a sensor as set forth in claim 8, wherein the method further comprises the further steps of:

providing a third electrode and a fourth electrode on said upper surface of said strain generative body on said flexible portion thereof, said third electrode being located in a positive area of said Y-axis and said fourth electrode being located in a negative area of the Y-axis;

providing on said sensor body a third opposite electrode facing said third electrode from a distance and a fourth opposite electrode facing said fourth electrode from a distance;

applying a third voltage between said third electrode and said third opposite electrode and applying a fourth voltage between said fourth electrode and said fourth opposite electrode so that a third repulsive-polarity coulomb force is produced between one of said third and third opposite or fourth and fourth opposite electrodes and a fourth attractive-polarity coulomb force is produced between the other thereof, said third and fourth coulomb forces constituting still another said force for producing still another spacial deviation of said working body;

detecting still another electric signal transformed by said detector means while said still another spacial deviation is produced; and

testing said detecting along said Y-axis from a relationship between said still another electric signal and said third and fourth applied voltages.

10. A method of testing a sensor as set forth in claim 9, wherein said polarities of all said voltages are varied over time.

11. A method of testing a sensor as set forth in claim 8, wherein said polarities of all said voltages are varied over time.

12. A method of testing a sensor, said sensor comprising:

a sensor body;

a strain generative body including a working potion for receiving a force, a flexible portion about said working portion and having flexibility to said force, and a fixed portion about said flexible portion and fixed to said sensor body;

a working body fixed to said working portion on a lower surface of said strain generative body, whereby said working body is suspended from said sensor body with three-dimensional freedom so that spacial deviation of said working body is produced by applying said force thereto; and

detector means for transforming said spacial deviation into an electric signal that indicates a direction and a magnitude of said force,

said method comprising the steps of;

defining an XYZ three-dimensional coordinate system so that an XY-plane thereof is on an upper surface of said strain generative body and an origin is located on said working portion thereof;

providing a first electrode and a second electrode on said upper surface of said strain generative body on said flexible portion thereof, said first electrode being located in a positive area of said X-axis and said second electrode being located in a negative area of the X-axis;

providing on said sensor body a first opposite electrode facing said first electrode from a distance and a second opposite electrode facing said second electrode from a distance;

applying a first voltage between said first electrode and said first opposite electrode and applying a second voltage between said second electrode and said second opposite electrode so that a first attractive-polarity coulomb force is produced between one of said first and first opposite or second and second opposite electrodes and a second attractive-polarity coulomb force is produced between the other thereof, said first and second coulomb forces constituting said force for producing said spacial deviation of said working body;

detecting an electric signal transformed by said detector means while said spacial deviation is produced; and

testing said detecting along said Z-axis from a relationship between said electric signal and said first and second applied voltages.

13. A method of testing a sensor as set forth in claim 12, wherein the method further comprises the further steps of:

providing a third electrode and a fourth electrode on said upper surface of said strain generative body on said flexible portion thereof, said third electrode being located in a positive area of said Y-axis and said fourth electrode being located in a negative area of the Y-axis;

providing on said sensor body a third opposite electrode facing said third electrode from a distance and a fourth opposite electrode facing said fourth electrode from a distance;

applying a third voltage between said third electrode and said third opposite electrode and applying a fourth voltage between said fourth electrode and said fourth opposite electrode so that a third repulsive-polarity coulomb force is produced between one of said third and third opposite or fourth and fourth opposite electrodes and a fourth attractive-polarity coulomb force is produced between the other thereof, said third and fourth coulomb forces constituting still another said force for producing still another spacial deviation of said working body;

detecting still another electric signal transformed by said detector means while said still another spacial deviation is produced; and

testing said detecting along said Y-axis from a relationship between said still another electric signal and said third and fourth applied voltages.

14. A method of testing a sensor as set forth in claim 13, wherein said polarities of all said voltages are varied over time.

15. A method of testing a sensor as set forth in claim 13, wherein the method further comprises the further steps of:

providing a third electrode and a fourth electrode on said upper surface of said strain generative body on said flexible portion thereof, said third electrode being located in a positive area of said X-axis and said fourth electrode being located in a negative area of the X-axis;

providing on said sensor body a third opposite electrode facing said third electrode from a distance and a fourth opposite electrode facing said fourth electrode from a distance;

applying a third voltage between said third electrode and said third opposite electrode and applying a fourth voltage between said fourth electrode and said fourth opposite electrode so that a third repulsive-polarity coulomb force is produced between one of said third and third opposite or fourth and fourth opposite electrodes and a fourth attractive-polarity coulomb force is produced between the other thereof, said third and fourth coulomb forces constituting still another said force for producing still another spacial deviation of said working body;

detecting still another electric signal transformed by said detector means while said still another spacial deviation is produced; and

testing said detecting along said X-axis from a relationship between said still another electric signal and said third and fourth applied voltages.

16. A method of testing a sensor as set forth in claim 15, wherein said polarities of all said voltages are varied over time.

17. A method of testing a sensor as set forth in claim 12, wherein said polarities of all said voltages are varied over time.