JP3145979B2 - Force / acceleration / magnetism detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force detecting device, and more particularly to a force detecting device suitable for detecting a force for each multidimensional component and applicable to detecting acceleration and magnetism.

[0002]

2. Description of the Related Art In the automobile industry, the machine industry, and the like, there is an increasing demand for a detection device capable of accurately detecting physical quantities such as force, acceleration, and magnetism. In particular, a small device capable of detecting these physical quantities for each of two-dimensional or three-dimensional components is desired.

In order to meet such demands, a gauge resistor is formed on a semiconductor substrate such as silicon, and mechanical strain generated in the substrate based on an externally applied force is converted into an electric signal using a piezoresistance effect. A force detecting device has been proposed. If a weight is attached to the detection part of this force detection device, an acceleration detection device that detects the acceleration applied to the weight as a force can be realized. If a magnetic material is attached, the magnetism acting on the magnetic material is detected as a force. The magnetic detection device can be realized.

[0004] For example, PCT / JP88 / 00395 and International Patent Application No.
The specification of CT / JP88 / 00930 discloses a force detecting device, an acceleration detecting device, and a magnetic detecting device based on the above-described principle.

[0005]

Generally, since the gauge resistance and the piezoresistive coefficient have a temperature dependency, in the above-described detecting device, if the temperature of the environment to be used fluctuates, the detected value includes an error. Become. Therefore, it is necessary to perform temperature compensation in order to perform accurate measurement. In particular, when used in the field of automobiles or the like, temperature compensation is required for a considerably wide operating temperature range from -40 ° C to + 120 ° C.

In order to manufacture the above-described detection device,
An advanced process for processing a semiconductor substrate is required, and expensive equipment such as an ion implantation apparatus is also required. For this reason, there is a problem that the manufacturing cost increases.

Accordingly, an object of the present invention is to provide a detection device capable of detecting physical quantities such as force, acceleration, and magnetism without performing temperature compensation, and which can be supplied at low cost.

[0008]

(1) A first aspect of the present invention defines a first axis and a second axis which are orthogonal to each other, and a force acting in a first axial direction and a second axis. in a force detecting device having a function of detecting independently the force exerted in the axial direction, so that displacement does not occur for the device housing
A fixed element fixed to, is connected via a flexible portion to the fixed element, based on the power of the first axial force or a second axial direction and acting from the outside, a flexible part Deflection
A displacement element that causes displacement in the first axial direction or the second axial direction with respect to the fixed element;
The first fixed electrode, the second fixed electrode, and the third fixed electrode formed on the fixed element so as to maintain the fixed state regardless of the displacement of
And the fourth fixed electrode and the displacement of the displacement element
A first displacement electrode, a second displacement electrode, a third displacement electrode, and a fourth displacement electrode, which are formed on the displacement element so as to be displaced in a first direction. The first fixed electrode and the first displacement electrode form a first capacitive element; and the second fixed electrode and the second displacement electrode face each other. And the second fixed electrode and the second displacement electrode
Is formed, the third fixed electrode and the third displacement electrode are arranged at positions facing each other, and the third fixed electrode and the third displacement electrode form a third capacitance element, The fourth fixed electrode and the fourth displacement electrode are arranged at positions facing each other, a fourth capacitance element is formed by the fourth fixed electrode and the fourth displacement electrode, and the displacement element is a first capacitor. When the displacement of the displacement element is displaced in the negative direction of the first axis, the distance between the electrodes of the first capacitance element decreases and the distance between the electrodes of the second capacitance element increases. When the distance between the electrodes of the first capacitive element increases and the distance between the electrodes of the second capacitive element decreases, and the displacement element is displaced in the positive direction of the second axis, the distance between the electrodes of the third capacitive element is reduced. As the distance decreases, the distance between the electrodes of the fourth capacitive element increases, and the displacement element When the negative electrode is displaced in the negative direction, the fixed electrodes and the displacement electrodes are arranged such that the distance between the electrodes of the third capacitive element increases and the distance between the electrodes of the fourth capacitive element decreases. The force acting in the first axial direction is detected based on the difference between the capacitance value of the first capacitance element and the capacitance value of the second capacitance element, and the capacitance value of the third capacitance element and the fourth capacitance element are detected. And the force acting in the second axial direction is detected based on the difference from the capacitance value.

(2) The second aspect of the present invention is the above-mentioned first aspect.
In the force detection device according to the above aspect, a fifth fixed electrode formed on the fixed element and a fifth displacement electrode formed on the displacement element are further provided, and the fifth fixed electrode and the fifth displacement electrode are provided. Are arranged at positions facing each other, a fifth capacitive element is formed by the fifth fixed electrode and the fifth displacement electrode, and a fifth capacitive element is formed orthogonally to both the first axis and the second axis. 3
And the displacement element is configured to generate a displacement in the third axial direction with respect to the fixed element based on an externally applied third axial force, wherein the displacement element has a third axis. When the displacement is displaced in the positive direction, the distance between the electrodes of the fifth capacitive element decreases or increases, and when the displacement element is displaced in the negative direction of the third axis, the distance between the electrodes of the fifth capacitive element is increased or The fifth fixed electrode and the fifth displacement electrode are arranged so as to decrease, and the force acting in the third axial direction can be detected based on the capacitance value of the fifth capacitive element. is there.

(3) A third aspect of the present invention is the above-mentioned first aspect.
Alternatively, in the force detection device according to the second aspect, an auxiliary electrode is provided at a position on the fixed element facing the displacement electrode, and a predetermined voltage is applied between the displacement electrode and the auxiliary electrode to act between the two. The displacement element can be displaced by Coulomb force.

(4) The fourth aspect of the present invention is the above-mentioned first aspect.
Alternatively, in the force detection device according to the second aspect, an auxiliary electrode is provided on the displacement element at a position facing the fixed electrode, and a predetermined voltage is applied between the fixed electrode and the auxiliary electrode to act between the two. The displacement element can be displaced by Coulomb force.

(5) The fifth aspect of the present invention is the above-mentioned first aspect.
In the force detection devices according to the fourth to fourth aspects, one of the plurality of displacement electrodes and the plurality of fixed electrodes is physically formed by a single common electrode.

(6) The sixth aspect of the present invention is the above-mentioned first aspect.
In the detection device according to the fifth to fifth aspects, by detecting a force generated based on an acceleration acting on the displacement element,
The acceleration can be detected.

(7) A seventh aspect of the present invention is the above-mentioned first aspect.
In the detection device according to the fifth to fifth aspects, at least a part of the displacement element is made of a magnetic material, and the magnetism can be detected by detecting a force generated based on a magnetic force acting on the magnetic material portion. It is like that.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. The embodiment described here is an example in which the force detection device according to the present invention is used as an acceleration detection device.

§1. Basic Embodiment of the Present Invention FIG. 1 is a side sectional view showing a structure of a basic embodiment using a force detecting device according to the present invention as an acceleration detecting device. The main components of this device are a fixed substrate 10, a displacement substrate 20, an operating body 30, and a device housing 40. FIG. 2A shows a bottom view of the fixed substrate 10. FIG. 1 shows a cross section of the fixed substrate 10 of FIG. 2A cut along the X-axis. The fixed substrate 10 is a disk-shaped substrate as shown, and the periphery thereof is fixed to the device housing 40. On the lower surface, a disk-shaped fixed electrode 11 is also formed.
On the other hand, FIG. 2B shows a top view of the displacement substrate 20. FIG.
FIG. 1 is a cross-sectional view of the displacement substrate 20 of FIG.
Is shown in The displacement substrate 20 is also a disk-shaped substrate as shown, and its periphery is fixed to the device housing 40.
On this upper surface, quadrant disk-shaped displacement electrodes 21 to 24 are formed. The action body 30 has a columnar shape as shown by a broken line in FIG.
0 is coaxially joined to the lower surface. The device housing 40 has a cylindrical shape and fixedly supports the periphery of the fixed substrate 10 and the displacement substrate 20.

The fixed substrate 10 and the displacement substrate 20 are arranged at predetermined intervals at positions parallel to each other. Each of them is a disk-shaped substrate, whereas the fixed substrate 10 is a substrate having high rigidity and less likely to bend, whereas the displacement substrate 20 is flexible and is a substrate which bends when a force is applied. . Eventually, the fixed board 10 functions as a fixed element fixed to the device housing 40, while the displacement board 20 is connected to this fixed element via a flexible portion,
The central portion of the displacement substrate 20 functions as a displacement element (an element that causes relative displacement with respect to the fixed element) together with the operating body 30. Now, as shown in FIG. 1, an action point P is defined at the center of gravity of the action body 30, and an XYZ three-dimensional coordinate system having the action point P as an origin is defined as shown in the figure. That is, the X-axis is defined in the right direction in FIG. 1, the Z-axis is defined in the upward direction, and the Y-axis is defined in the direction perpendicular to the paper surface toward the back side of the paper surface. Then, the displacement element is connected to the fixed element while being displaceable in the X, Y, and Z axial directions.

If the entire apparatus is mounted on, for example, an automobile, acceleration is applied to the operating body 30 based on the running of the automobile. Due to this acceleration, an external force acts on the action point P. In the state where no force is applied to the point of action P, as shown in FIG.
1 to 24 are kept in parallel at a predetermined interval. However, for example, a force Fx in the X-axis direction is applied to the point of action P.
When this acts, this force Fx generates a moment force on the displacement substrate 20, and as shown in FIG.
Will bend. Due to this bending, the distance between the displacement electrode 21 and the fixed electrode 11 increases, but the distance between the displacement electrode 23 and the fixed electrode 11 decreases. Assuming that the force applied to the point of action P is -Fx in the opposite direction, the bending in the opposite relationship to this occurs. On the other hand, when the force Fy or −Fy in the Y direction acts, the distance between the displacement electrode 22 and the fixed electrode 11 and the displacement electrode 24 and the fixed electrode 1
A similar change occurs for the distance to 1. In addition, when the force Fz in the Z-axis direction acts, as shown in FIG. 4, all of the displacement electrodes 21 to 24 come close to the fixed electrode 11, and when the force −Fz in the opposite direction acts, , All of the displacement electrodes 21 to 24 move away from the fixed electrode 11.

Here, consider a capacitive element formed by each electrode. The lower surface of the fixed substrate 10 shown in FIG. 2A and the upper surface of the displacement substrate 20 shown in FIG. Accordingly, the facing relationship between the electrodes is such that each of the displacement electrodes 21 to 24 faces each facing portion of the fixed electrode 11. In other words, the fixed electrode 11 becomes one common electrode, but the displacement electrodes 21 to 2
Numeral 4 is a localized electrode localized in a quadrant area.
Even if the number of common electrodes is one, the four localized electrodes are electrically independent from each other.
One group of capacitors can be formed. The capacitive element belonging to the first group is a combination of the displacement electrode 21 and the fixed electrode 11 arranged in the negative direction of the X axis, and the capacitive element belonging to the second group is arranged in the positive direction of the Y axis. The capacitance element belonging to the third group is a combination of the displacement electrode 23 and the fixed electrode 11 arranged in the positive direction of the X axis, and the fourth group is a combination of the displacement electrode 22 and the fixed electrode 11. Is a combination of the displacement electrode 24 and the fixed electrode 11 arranged in the negative direction of the Y-axis. Now, the capacitance of each of these capacitive elements is represented by C1, C
2, C3 and C4. As shown in FIG. 1, when no force is applied to the point of action P, the distance between the electrodes of each capacitance element is kept the same, and the capacitance takes a standard value C0. That is, C1 =
C2 = C3 = C4 = C0. However, as shown in FIG. 3 or FIG. 4, when a force acts on the action point P and the displacement substrate 20 bends, the electrode spacing of each capacitance element changes, and the capacitance of the capacitance element is different from the standard value C0. It will be a different value.
In general, the capacitance C of a capacitance element is determined by C = εS / d, where S is an electrode area, d is an electrode interval, and ε is a dielectric constant. Therefore, the capacitance C increases as the electrode spacing decreases, and decreases as the distance increases.

For example, as shown in FIG. 3, when a force Fx in the X-axis direction acts on the point of action P, the distance between the displacement electrode 21 and the fixed electrode 11 increases, so that C1 <C0.
Since the distance between the displacement electrode 23 and the fixed electrode 11 is close,
C3> C0. At this time, the displacement electrodes 22 and 24
And the distance between the fixed electrode 11 and the fixed electrode 11 are partially approached and partially moved away from each other, so that the two portions cancel each other out, and the capacitance does not change as C2 = C4 = C0. On the other hand, as shown in FIG. 4, when a force Fz in the Z-axis direction acts on the action point P, the intervals between the displacement electrodes 21 to 24 and the fixed electrode 11 are all short, and (C1 to C4)> C0. . As described above, the pattern of change in the capacitance of the four groups of capacitance elements differs depending on the direction of the acting force.

FIG. 5 is a table showing patterns of changes in capacitances C1 to C4 of the four groups of capacitance elements. In this table, “0” indicates that there is no change in the capacitance (that is, the value remains at the standard value C0), “+” indicates that the capacitance increases, and “−” indicates that the capacitance increases. Indicates that the capacitance becomes smaller. For example, the column of Fx in FIG. 5 shows changes in the capacitances C1 to C4 when the force Fx in the X-axis direction acts on the point of action P as shown in FIG. , C1 become smaller, C3 becomes larger, and C2 and C4 remain unchanged. In this manner, the direction of the applied force can be recognized based on the pattern of change in each capacitance. Also, the magnitude of the applied force can be recognized by looking at the degree of change (that is, how large or small the capacitance has been).

FIG. 6 shows a basic circuit for detecting the applied force for each axial component. The converters 51 to 54 are configured by circuits that convert the capacitances C1 to C4 of the respective capacitance elements into voltage values V1 to V4. For example, a configuration may be adopted in which the capacitance value C is converted into a frequency value f by a CR transmitter or the like, and then the frequency value f is further converted into a voltage value V by a frequency / voltage conversion circuit. of course,
Means for directly converting the capacitance value to a voltage value may be used. The differential amplifier 55 is a circuit that calculates the difference between the voltage values V1 and V3 and outputs the difference as the X-axis direction component ± Fx of the force to be detected. As can be seen by referring to the columns of Fx and -Fx in FIG.
It is found by taking the difference from 3. Further, the differential amplifier 56 is a circuit that calculates the difference between the voltage values V2 and V4 and outputs the difference as the Y-axis component ± Fy of the force to be detected.
As can be seen from the columns of Fy and -Fy in FIG. 5, the Y-axis direction component ± Fy is obtained by taking the difference between C2 and C4. Further, the adder 57 outputs voltage values V1 to V
4 and the Z-axis component ± F of the force to be detected.
It is a circuit that outputs as z. Fz and -Fz in FIG.
As can be understood by referring to the column of, the Z-axis direction component ± Fz
Is obtained by taking the sum of C1 to C4.

According to the principle described above, if a predetermined wiring is provided to each of the electrodes shown in FIGS. 2A and 2B and a detection circuit as shown in FIG. The applied force can be detected as an electric signal for each three-dimensional axial component. That is, the acceleration acting on the operating body 30 can be detected as an electric signal for each three-dimensional axial component. Since the detection of each axial component is performed completely independently, interference with other axes does not occur and accurate detection is possible. Further, the temperature dependence of the detected value is negligible, and no processing for temperature compensation is required. Moreover, since it can be realized with a simple structure in which electrodes are formed on the substrate, the manufacturing cost is low.

The detection circuit shown in FIG. 6 is shown as an example, and another circuit may be used. For example, a capacitance value may be converted to a frequency value using a CR oscillation circuit, and the converted value may be input to a microprocessor, and a three-dimensional acceleration may be obtained by digital calculation.

§2. Embodiment showing the Material of Each Part Next, the material of each part constituting the above-described acceleration detecting device will be described. In order to perform detection based on the above-described principle, the following conditions should be satisfied in terms of material. (1) Each electrode is made of a conductive material. (2) Each localized electrode shall be electrically insulated from each other. (3) The displacement substrate can be displaced based on an external force applied to the working body.

As long as such conditions are satisfied, any material may be used. Here, some preferred embodiments using practical materials will be described.

In the embodiment shown in FIG. 7, the fixed substrate 10a,
This is an example in which metal is used for all of the displacement substrate 20a and the working body 30a. The displacement substrate 20a and the working body 30a are formed integrally. Of course, these may be made separately and then joined together. Device housing 40
Are fixedly supported by fitting the periphery of each substrate into a support groove 41 formed on the inner surface thereof, for example. Since the fixed substrate 10a itself functions as the fixed electrode 11 as it is, there is no need to separately form the fixed electrode 11. The displacement electrodes 21a to 24a cannot be formed directly on the displacement substrate 20a because the displacement substrate 20a is made of metal. Therefore, the displacement electrodes 21a to 24a are provided via an insulating layer 25a made of a material such as glass or ceramic.
Is formed on the displacement substrate 20a. The displacement substrate 2
In order to make the Oa flexible, the thickness of the Oa may be reduced, or the Oa may be corrugated so as to be easily deformed.

In the embodiment shown in FIG. 8, the fixed substrate 10b,
This is an example in which an insulator such as glass or ceramic is used for all of the displacement substrate 20b and the working body 30b. The displacement substrate 20b and the working body 30b are formed integrally. The device housing 40 is formed of metal or plastic, and is fixedly supported by fitting the periphery of each substrate into a support groove 41 formed on the inner surface. Fixed electrodes 11b made of metal are formed on the lower surface of the fixed substrate 10b, and displacement electrodes 21b to 24b made of metal are formed on the upper surface of the displacement substrate 20b. In order to make the displacement substrate 20b flexible,
The thickness may be reduced, or a synthetic resin having flexibility may be used instead of glass or ceramic. Alternatively, deformation may be facilitated by partially providing a through hole.

In the embodiment shown in FIG. 9, a fixed substrate 10c,
This is an example in which a semiconductor such as silicon is used for all of the displacement substrate 20c and the acting body 30c. The displacement substrate 20c and the working body 30c are formed integrally. The device housing 40 is
The periphery of each substrate is fitted and fixedly supported by a support groove 41 formed of metal or plastic and formed on the inner surface. Fixed electrode 11 located inside the lower surface of fixed substrate 10c
c and the displacement electrodes 21c to 24c located inside the upper surface of the displacement substrate 20c are formed by diffusing impurities at a high concentration. In order to make the displacement substrate 20c flexible, the thickness may be reduced or a through hole may be provided partially.

As described above, an example in which a metal, an insulator, or a semiconductor is used as a material of each component has been described, but a combination of these materials may be used for each component.

§3. Detects triaxial components with independent electrodes
Embodiments to be Issued In the basic embodiment described above, the detection circuit as shown in FIG. 6 has been described. In this detection circuit, ± Fx or ± F
The same capacitor is used for detecting y and the capacitor for detecting ± Fz. In other words, biaxial direction components have been detected by using a single localized electrode. In the embodiment described here, the triaxial components are detected by completely independent dedicated electrodes. FIG. 10 shows a top view of the displacement substrate 20d used in this embodiment. As compared with the displacement substrate 20 in the basic embodiment shown in FIG. 2B, the pattern of forming the localized electrodes is slightly more complicated, and a total of eight localized electrodes are formed. The eight localized electrodes are basically divided into four groups. The localized electrodes belonging to the first group are the electrodes 21d and 21e arranged in the negative direction of the X axis, and the localized electrodes belonging to the second group are the electrodes 22d arranged in the positive direction of the Y axis. 22e, and the localized electrodes belonging to the third group are the electrodes 2 arranged in the positive direction of the X-axis.
3d and 23e, and the localized electrodes belonging to the fourth group are the electrodes 24d and 24e arranged in the negative direction of the Y-axis.

Now, the capacitances of the four capacitance elements formed by the combination of the four electrodes 21d to 24d hatched by dots in FIG. 10 and the fixed electrode 11 opposed thereto are C1 to C4, respectively. , The capacitances of the four capacitance elements formed by the combination of each of the four electrodes 21 e to 24 e hatched by oblique lines and the fixed electrode 11 opposed thereto are represented by C 1 ′ to C 1, respectively.
4 '. And about these eight capacitive elements,
A detection circuit as shown in FIG. 11 is configured. Here, the converters 51 to 54 convert the capacitances C1 to C4 into voltages V1 to V4.
The differential amplifiers 55 and 56 are circuits for amplifying and outputting the difference between the two input voltage values. The differential amplifiers 55 and 56 output ± Fx and ± Fy detection values, respectively, as in the above-described basic embodiment. The feature of this embodiment is that four capacitances C1 'to C4' are connected in parallel, and a voltage V5 corresponding to the sum of the capacitances is generated by a converter 58, and this voltage is ± F
This is the point of outputting as the detected value of z. This detection principle,
Consider the localized electrode shown in FIG.
± Fx is detected by d and 23d, and electrodes 22d and 2d are detected.
± Fy is detected by 4d, and the electrodes 21e, 22e,
± Fz is detected by 23e and 24e. In this manner, the components in the three axial directions can be detected by the independent electrodes.

As described above, for convenience of explanation, the electrodes 21e to 24e
Have been shown with independent electrodes, but in practice, as is clear from the circuit diagram of FIG.
The capacitance element constituted by 24e is connected in parallel. Therefore, these four electrodes may be integrally formed on the flexible substrate 20d.

This embodiment is convenient when adjusting the detection sensitivity for each axial component. For example, in FIG. 10, hatched electrodes 21e, 21e,
If the area of 22e, 23e, 24e is increased, the detection sensitivity in the Z-axis direction can be increased. In general, in an apparatus capable of detecting components in three axial directions, it is preferable that the detection sensitivity of each of the three axes is designed to be substantially equal.
In this embodiment, the detection sensitivities of the three axes can be made substantially equal by adjusting the area ratio between the hatched area indicated by oblique lines in FIG. 10 and the hatched area indicated by dots.

§4. Implementation with changing electrode formation pattern
In the basic embodiment described above, as shown in FIG. 2A, the fixed electrode 11 formed on the fixed substrate 10 is a single common electrode, and the four fixed electrodes formed on the displacement substrate 20 are four. Of localized electrodes 21 to 24. The present invention is not limited to such a configuration, and may have a completely opposite configuration. That is, the fixed electrodes 11 formed on the fixed substrate 10 may be four localized electrodes, and the displacement electrodes formed on the displacement substrate 20 may be one common electrode. Alternatively, it is also possible to form four localized electrodes on each of the substrates. Further, the number of localized electrodes formed on one substrate is not necessarily required to be four. For example, eight or sixteen localized electrodes may be formed. Also,
As in a displacement substrate 20f shown in FIG. 12, only two localized electrodes 21f and 23f may be formed.
In this case, it is not possible to detect the component in the Y-axis direction,
Detection in two dimensions consisting of the X-axis direction component and the Z-axis direction component is possible. Furthermore, if only one-dimensional detection is performed, the shape of the electrodes on both substrates is not limited to a circle or a sector, but may be any shape. Each substrate does not necessarily have to be disk-shaped.

§5. Embodiment with Test Function Generally, when mass-producing some detection device and putting it on the market,
In a test process before shipping, an operation for confirming a normal detection operation is performed. In the acceleration detection device described above,
It is preferred to test before shipping. In order to test the acceleration detecting device, it is general to actually apply acceleration and check an electric signal output at this time. However, such a test requires equipment for generating acceleration, and the test system becomes large.

In the embodiment described below, a test before shipment can be performed without using such a large-scale test system. FIG. 13 is a side sectional view showing the structure of the acceleration detecting device according to the embodiment having the test function. The main components of this device are a fixed substrate 60, a displacement substrate 70, an operating body 75, an auxiliary substrate 80, and a device housing 40. FIG. 14 shows a bottom view of the fixed substrate 60.
FIG. 13 shows a cross section of the fixed substrate 60 of FIG. 14 cut along the X-axis. The fixed substrate 60 is a metal disk-shaped substrate, and the periphery thereof is fixed to the device housing 40. On this lower surface, four quadrant-shaped fixed electrodes 61 to 64 are formed via an insulating layer 65 such as glass. The displacement substrate 70 is a flexible metal disk, and the periphery thereof is also fixed to the device housing 40. A columnar acting body 75 is coaxially joined to the lower surface of the displacement substrate 70. The upper surfaces of the displacement substrates 70 are fixed electrodes 61 to 64.
Is formed as one displacement electrode. The feature of this embodiment is that an auxiliary substrate 80 is further provided. FIG. 15 shows a top view of the auxiliary substrate 80. FIG. 1 is a cross-sectional view of the auxiliary substrate 80 of FIG. 15 cut along the X axis.
It is shown in FIG. The auxiliary substrate 80 is a metal disk-shaped substrate having a circular through hole formed in the center as shown in the figure, and the periphery is fixed to the device housing 40. As shown by the dashed line in FIG.
5 is inserted. On the upper surface of the auxiliary substrate 80, four auxiliary electrodes 81 to 84 are formed via an insulating layer 85 such as glass. Note that the lower surface of the displacement substrate 70 constitutes one auxiliary electrode facing the auxiliary electrodes 81 to 84.
As described above, the displacement substrate 70 is a metal lump formed integrally with the operating body 75, and the upper surface thereof is fixed to the fixed electrodes 61 to 6.
4 acts as a single displacement electrode facing the electrode 4, and its lower surface acts as a single auxiliary electrode facing the auxiliary electrodes 81 to 84.

According to such a configuration, the fixed electrodes 61 to 61
64 and a displacement electrode (upper surface of the displacement substrate 70) opposed thereto, four sets of capacitance elements can be formed, and the acceleration applied to the action body 75 can be detected based on the change in the capacitance. Can be performed as described above. Further, the auxiliary electrodes 81 to 84 and the displacement electrodes (the displacement substrate 7)
(Lower surface of 0), four sets of capacitive elements can be formed to detect acceleration. The feature of this device is that it is possible to create a state equivalent to the acceleration applied without actually applying the acceleration. That is, when a predetermined voltage is applied between the electrodes, a Coulomb force acts between the two, and the displacement substrate 70 bends in a predetermined direction. For example, in FIG. 13, when voltages of different polarities are applied to the displacement substrate 70 and the electrode 63, an attractive force based on Coulomb force acts between the two and the displacement substrate 70 and the electrode 81.
If voltages of different polarities are applied to the above, an attractive force based on Coulomb force acts between the two. When such an attractive force acts, the displacement substrate 70 is moved in the same manner as when the force Fx in the X-axis direction acts as shown in FIG. 3 even if no force is actually acting on the acting body 75. Deflection will occur. Also, if a voltage of the same polarity is applied to the displacement substrate 70 and the electrodes 81 to 84, a repulsive force based on Coulomb force acts between the two, and even if no force is actually acting on the acting body 75, as shown in FIG. 4, the displacement substrate 70 bends in the same manner as when the force Fz in the Z-axis direction is applied. In this way, by applying a voltage of a predetermined polarity to each electrode, it is possible to create a state equivalent to the fact that forces in various directions actually act. Thus, the device can be tested without actually applying acceleration.

Further, the structure to which the auxiliary substrate 80 is added as shown in FIG.
There is also a secondary effect that the 0 can be prevented from being damaged. Although the displacement substrate 70 has flexibility, it may be damaged when an excessive force is applied. However, according to the structure shown in FIG. 13, even when an excessive force is applied, the displacement of the displacement substrate 70 is limited to a predetermined range, so that no excessive displacement until damage is caused. That is, FIG.
When an excessive acceleration is applied in the lateral direction (X or Y axis direction), the side surface of the acting body 75 contacts the inner surface of the through hole of the auxiliary substrate 80 and the upper or lower surface of the displaced displacement substrate 70 Fixed electrode 61 to 64 or auxiliary electrode 8
1 to 84, and no further displacement occurs. Also,
When an excessive acceleration is applied in the vertical direction (Z-axis direction) in FIG. 13, the upper surface or the lower surface of the displaced displacement substrate 70 abuts on the fixed electrodes 61 to 64 or the auxiliary electrodes 81 to 84, and any further displacement is caused. Does not occur.

FIG. 16 is a side sectional view showing a state in which the acceleration detecting device having the structure shown in FIG. Between each electrode and the external terminals 91 to 93,
The electrodes are connected by bonding wires 94 to 96 (actually, electrically independent electrodes are respectively connected to dedicated external terminals by dedicated bonding wires, but only the main wiring is shown in the drawing. is there).
The upper surface of the fixed substrate 60 is joined to the inner top surface of the device housing 40, and is firmly held so as not to bend.

[0041]§6. Modified example using piezoelectric element  In the various embodiments described so far, the acceleration based
The force is the static force of the capacitive element composed of the displacement electrode and the fixed electrode.
It is detected as a change in the capacitance value. Here,
Here is a modified example in which this capacitive element is replaced with a piezoelectric element.
Keep it.

FIG. 17 shows an embodiment of an acceleration detecting device according to this modification. The basic configuration of the device of this embodiment is common to the various embodiments described above. That is, the fixed substrate 10f and the displacement substrate 20f are mounted inside the device housing 40 so as to face each other. In this embodiment,
Both substrates are insulators, but may be made of metal or semiconductor. When an external force acts on the action body 30f, the displacement substrate 20f bends. As a result, the fixed electrode 11
The distance between f, 12f and the displacement electrodes 21f, 22f opposed thereto changes. In the above-described embodiment, the change in the distance between the two electrodes is detected as a change in the capacitance. In the present embodiment, this can be detected as a voltage value. for that reason,
The piezoelectric elements 101 and 102 are formed so as to be sandwiched between the fixed electrodes 11f and 12f and the displacement electrodes 21f and 22f. The compression force acts on the piezoelectric elements 101 and 102 when the distance between the two electrodes decreases, and the tensile force acts on the piezoelectric elements 101 and 102 when the distance between the two electrodes increases.
A voltage corresponding to each is generated by the piezoelectric effect.
Since this voltage can be directly taken out from both electrodes, the applied external force can be output directly as a voltage value.

As the piezoelectric elements 101 and 102, for example, PZT ceramics (solid solution of lead titanate and lead zirconate) can be used, and these may be mechanically connected between both electrodes. FIG. 17 shows only the side section, but in order to detect three-dimensional acceleration, FIG.
As in the case of the electrode arrangement shown in FIG. Alternatively, similarly to the electrode arrangement shown in FIG. 10, eight sets (substantially four of them are used to detect the force in the Z-axis direction).
(The set can be combined into one). In addition, to detect two-dimensional acceleration, FIG.
It is sufficient to arrange two sets of piezoelectric elements in the same manner as the electrode arrangement shown in FIG. Even when housed in a specific device housing 40, the configuration is almost the same as that of the embodiment shown in FIG.
93 output a voltage value directly.

A secondary effect of the present embodiment shown in FIG. 17 is that the piezoelectric elements 101 and 102 have a function of protecting the displacement substrate 20f. That is, even when an excessive force is applied, the displacement substrate 20f is bent only up to a predetermined limit due to the presence of the piezoelectric elements 101 and 102, and is not damaged. Further, similarly to the embodiment having the test function described above, it is also possible to perform a pseudo test in which Coulomb force is applied between both electrodes.

§7. Other Embodiments The present invention has been described based on some embodiments, but the present invention is not limited to only these embodiments and can be implemented in various other modes. In particular, in the above-described embodiment, the example in which the present invention is applied to the acceleration detection device that detects the acceleration applied to the operating object has been described.
The basic concept of the present invention resides in a mechanism for detecting a force acting on an acting body based on some physical phenomenon, and is applicable to a device for directly detecting a force instead of an acceleration.
FIG. 18 is a side sectional view of a force detecting device having substantially the same structure as the acceleration detecting device shown in FIG. A through-hole 42 is formed in the lower surface of the device housing 40, and a tentacle 76 extending from the operating body 75 is inserted into the through-hole 42. Thus,
The force acting on the tip of the touch element 76 can be directly detected. In addition, in the acceleration detecting device shown in FIG. 16, if the operating body 75 is formed of a magnetic material such as iron, cobalt, or nickel, when the operating body 75 is placed in a magnetic field, a force based on magnetism is applied to the operating body 75. Because it acts, it is possible to detect magnetism. As described above, the present invention is also applicable to a magnetic detection device.

[0046]

As described above, according to the force detecting device of the present invention, the force detecting device is formed by the four displacement electrodes displaced by the force to be detected and the four fixed electrodes fixed opposite thereto. Since the force is detected based on the capacitance values of the four capacitive elements, a low-cost detection device capable of detecting physical quantities such as force, acceleration, and magnetism without performing temperature compensation is realized. Will be able to gain.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a structure of an acceleration detection device according to a basic embodiment of the present invention.

2A is a bottom view of a fixed substrate in the device shown in FIG. 1, and FIG. 2B is a top view of a displacement substrate in the device shown in FIG.

FIG. 3 is a side sectional view showing a state where a force Fx in an X-axis direction acts on the device shown in FIG. 1;

FIG. 4 is a side sectional view showing a state where a force Fz in a Z-axis direction acts on the device shown in FIG. 1;

FIG. 5 is a table showing the principle of force detection in the device shown in FIG.

FIG. 6 is a detection circuit diagram for application to the device shown in FIG. 1;

FIG. 7 is a diagram showing an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of a metal material.

8 is a diagram showing an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of an insulating material.

9 is a diagram showing an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of a semiconductor material.

FIG. 10 is a top view of a displacement board of an acceleration detection device according to a modification of the device shown in FIG.

11 is a detection circuit diagram applied to the device shown in FIG.

FIG. 12 is a top view of a displacement substrate according to an embodiment that performs detection only in two dimensions.

FIG. 13 is a side sectional view showing the structure of the acceleration detection device according to the embodiment having a test function.

FIG. 14 is a bottom view of a fixed substrate in the apparatus of FIG.

FIG. 15 is a top view of an auxiliary substrate in the apparatus of FIG.

16 is a side sectional view showing a state where the acceleration detecting device having the structure shown in FIG.

FIG. 17 is a side sectional view showing a structure of an embodiment of an acceleration detecting device using a piezoelectric element according to a modification of the present invention.

18 is a side sectional view of a force detection device having substantially the same structure as the acceleration detection device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Fixed board 11 ... Fixed electrode 20 ... Displacement board 21-24 ... Displacement electrode 25 ... Insulating layer 30 ... Working body 40 ... Device housing 41 ... Support groove 42 ... Through-hole 51-54 ... Converter 55, 56 ... Difference Dynamic amplifier 57 ... Adder 58 ... Converter 60 ... Fixed substrate 61-64 ... Fixed electrode 65 ... Insulating layer 70 ... Displacement substrate 75 ... Working body 76 ... Tactor 80 ... Auxiliary substrate 81-84 ... Auxiliary electrode 85 ... Insulating layer 91 to 93 external terminals 94 to 96 bonding wires 101 and 102 piezoelectric elements P operating points

Claims (7)

(57) [Claims] 1. A function of defining a first axis and a second axis orthogonal to each other, and independently detecting a force applied in the first axis direction and a force applied in the second axis direction. a force detection device having a device and a fixed element displaceable against the housing is fixed so as not to cause, connected via a flexible portion to said fixed element, said first exerted from the outside The flexible portion being deflected based on the axial force of the second or the second axial force.
Thus, a displacement element that causes displacement in the first axial direction or the second axial direction with respect to the fixed element, and a fixed state is maintained regardless of the displacement of the displacement element.
A first fixed electrode formed on the fixing element,
, A third fixed electrode, a fourth fixed electrode, and a first displacement electrode, a second displacement electrode, and a third displacement electrode formed on the displacement element so as to be displaced with the displacement of the displacement element. A displacement electrode and a fourth displacement electrode, wherein the first fixed electrode and the first displacement electrode are disposed at positions facing each other, and the first fixed electrode and the first
A first capacitive element is formed by the second fixed electrode and the second fixed electrode. The second fixed electrode and the second displacement electrode are disposed at positions facing each other.
And the third fixed electrode and the third displacement electrode are arranged at positions facing each other, and the third fixed electrode and the third
And the fourth fixed electrode and the fourth displacement electrode are arranged at positions opposing each other, and the fourth fixed electrode and the fourth
A fourth capacitive element is formed by the displacement electrodes of the first and second elements, and when the displacement element is displaced in the positive direction of the first axis, the distance between the electrodes of the first capacitive element is reduced and the second capacitive element is reduced. When the inter-electrode distance of the capacitive element increases and the displacement element is displaced in the negative direction of the first axis, the inter-electrode distance of the first capacitive element increases and the second
When the distance between the electrodes of the capacitive element decreases and the displacement element is displaced in the positive direction of the second axis, the distance between the electrodes of the third capacitive element decreases and the electrode of the fourth capacitive element decreases. When the distance increases and the displacement element is displaced in the negative direction of the second axis, the distance between the electrodes of the third capacitance element increases and the distance between the electrodes of the fourth capacitance element decreases. The fixed electrodes and the displacement electrodes are arranged as described above, and act in the first axial direction by a difference between the capacitance value of the first capacitance element and the capacitance value of the second capacitance element. And a force acting in the second axial direction is detected based on a difference between a capacitance value of the third capacitance element and a capacitance value of the fourth capacitance element. Force detection device. 2. The force detection device according to claim 1, further comprising a fifth fixed electrode formed on the fixed element and a fifth displacement electrode formed on the displacement element. The fixed electrode and the fifth displacement electrode are arranged at positions facing each other, a fifth capacitive element is formed by the fifth fixed electrode and the fifth displacement electrode, and a first axis And a third axis perpendicular to both the second axis and the second axis, wherein, based on an externally applied force in the third axial direction, the displacement element has a third axial direction with respect to the fixed element. When the displacement element is displaced in the positive direction of the third axis,
When the distance between the electrodes of the fifth capacitive element decreases or increases and the displacement element is displaced in the negative direction of the third axis, the distance between the electrodes of the fifth capacitive element increases or decreases. And disposing the fifth fixed electrode and the fifth displacement electrode, and detecting the force acting in the third axial direction based on the capacitance value of the fifth capacitive element. Characteristic force detection device. 3. The force detection device according to claim 1, wherein an auxiliary electrode is provided on the fixed element at a position facing the displacement electrode, and a predetermined voltage is applied between the displacement electrode and the auxiliary electrode. A force detection device characterized in that a displacement can be generated in a displacement element by a Coulomb force applied between the two and applied. 4. The force detection device according to claim 1, wherein an auxiliary electrode is provided on the displacement element at a position facing the fixed electrode, and a predetermined voltage is applied between the fixed electrode and the auxiliary electrode. A force detection device characterized in that a displacement can be generated in a displacement element by a Coulomb force applied between the two and applied. 5. The force detecting device according to claim 1, wherein one of the plurality of displacement electrodes and the plurality of fixed electrodes is physically formed by a single common electrode. Force detection device. 6. The detection device according to claim 1, wherein the acceleration can be detected by detecting a force generated based on the acceleration acting on the displacement element. Acceleration detection device. 7. The detecting device according to claim 1, wherein at least a part of the displacement element is made of a magnetic material, and a force generated based on a magnetic force acting on the magnetic material portion is detected. A magnetic detection device characterized by being able to detect magnetism.