US 6,474,133 B1Granted

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

OwnerKazuhiro Okadainventor

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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′).

Claims17

Dependent claims

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.

6 more elements

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.

10 more elements

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.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/168,024Filed 15 Dec 1993 · division
Priority: JP 1-34335428 Dec 1989
Granted: 5 Nov 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

G01P 15/125
With conversion into electric or magnetic values: by capacitive pick-up
G01L 1/148
Using capacitors: using semiconductive material, e.g. silicon
G01L 1/18
Measuring force or stress, in general: using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies…
G01L 5/162
Using variations in ohmic resistance: of piezoresistors