JP2841240B2 - Force / acceleration / magnetism detection device - Google Patents

Description

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 the detection of acceleration and magnetism. About.

[Conventional technology]

In the automotive industry, the machine industry, and the like, there is an increasing demand for a detection device that can accurately detect 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 respond to such demands, a gauge resistor is formed on a semiconductor substrate such as silicon, and force detection that converts mechanical strain generated on the substrate based on externally applied force into an electric signal using the piezoresistance effect. A 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.

For example, PCT /
JP88 / 00395 specification and PCT / JP88 / 00930 specification include a force detection device, an acceleration detection device,
A magnetic detection device is disclosed.

[Problems to be solved by the invention]

In general, since the gauge resistance and the piezoresistance coefficient have temperature dependence, in the above-described detection device, if the temperature of the environment to be used fluctuates, the detection value includes an error. Therefore, in order to perform accurate measurement, it is necessary to perform temperature compensation. In particular, when used in fields such as automobiles,
Temperature compensation is required for a fairly wide operating temperature range from -40 ° C to + 120 ° C.

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

Therefore, an object of the present invention is to provide a detection device that can detect physical quantities such as force, acceleration, and magnetism without performing temperature compensation, and that can supply the detection value at low cost.

[Means for solving the problem]

(1) In a first aspect of the present invention, in the force detection device, a fixed portion fixed to the device housing, an operating portion to which an external force is transmitted, and a force detecting device formed between the fixed portion and the operating portion. A flexible substrate having a flexible portion having flexibility; a fixed substrate fixed to the device housing so as to face the flexible substrate; An operating body for transmitting to the operating portion of the substrate; a displacement electrode formed on the surface of the flexible substrate facing the fixed substrate; and a fixed electrode formed on the surface of the fixed substrate facing the flexible substrate. Alternatively, one or both of the fixed electrodes are arranged at predetermined intervals along a predetermined axis on one electrode forming surface, and are constituted by two sets of electrically independent localized electrodes. Two groups of electrodes each facing each other using a set of localized electrodes The capacitance element of the two groups is formed, and the predetermined axial component of the force acting on the acting body is detected based on the difference between the capacitances of the capacitance elements of the two groups. The axial component perpendicular to the electrode forming surface of the force acting on the acting body is detected based on the sum of the capacitances.

(2) A second invention of the present application is the force detection device, wherein a fixed portion fixed to the device housing, an operating portion to which an external force is transmitted, and a force detecting device formed between the fixed portion and the operating portion. A flexible substrate having a flexible portion having flexibility; a fixed substrate fixed to the device housing so as to face the flexible substrate; An operating body for transmitting to the operating portion of the substrate; a displacement electrode formed on the surface of the flexible substrate facing the fixed substrate; and a fixed electrode formed on the surface of the fixed substrate facing the flexible substrate. Alternatively, when one or both of the fixed electrodes are defined as an origin at an intersection of both axes of a first axis and a second axis orthogonal to each other on one electrode forming surface, the positive and negative directions of each axis are respectively set. Are constituted by four sets of localized electrodes, each of which is electrically independent, The four groups of localized electrodes are used to form four groups of capacitance elements each consisting of electrodes facing each other, and the capacitance elements belonging to two groups on the first axis among the four groups of capacitance elements The force of the first axial component is detected from the difference in capacitance between the four groups, and among the four groups of capacitance elements, the second group is located on the second axis. In this configuration, the force of the second axial component is detected.

(3) The third invention of the present application is the force detection device according to the second invention, wherein the first and second axes are both determined by the sum of the capacitances of the capacitance elements belonging to four groups. The force of the third axial component orthogonal to is detected.

(4) The fourth invention of the present application is the force detection device according to the second invention described above, further comprising: a fifth set of localized electrodes electrically independent of the four sets of localized electrodes; Of the fifth group using the localized electrodes of the third group, and the third axis orthogonal to both the first axis and the second axis due to the capacitance of the fifth group. This is to detect the force of the directional component.

(5) The fifth invention of the present application is the force detection device according to the first to fourth inventions, wherein an auxiliary substrate is further provided such that the fixed substrate, the flexible substrate, and the auxiliary substrate are arranged so as to face each other in this order. Forming a first auxiliary electrode on a surface of the flexible substrate facing the auxiliary substrate, forming a second auxiliary electrode on a surface of the auxiliary substrate facing the flexible substrate, between the first auxiliary electrode and the second auxiliary electrode, or A predetermined voltage is applied between the displacement electrode and the fixed electrode, and a displacement is generated in the flexible substrate by the cloning force acting between the two, so that the flexible substrate can be kept in a state equivalent to a state where an external force is applied. It was made.

(6) The sixth invention of the present application is the force detection device according to the fifth invention, wherein the flexible substrate is formed of a conductive material, and the first auxiliary electrode and the displacement electrode are formed of the conductive flexible substrate. Is formed by a part of the above.

(7) According to a seventh aspect of the present invention, in the detection device according to the first to sixth aspects, the acceleration can be detected by detecting a force generated based on the acceleration acting on the operating body. Things.

(8) The eighth invention of the present application is the detecting device according to the first to sixth inventions, wherein the operating body is made of a magnetic material, and a force generated based on a magnetic force acting on the operating body is detected. ,
The magnetic field can be detected.

(Operation)

(1) In the force detection device according to the first aspect of the present invention, when an external force is applied to the working body, the flexible substrate bends, and the distance between the displacement electrode and the fixed electrode changes. Therefore, the capacitance between both electrodes changes. This change in capacitance depends on an externally applied force, and the detection of the change in capacitance makes it possible to detect the force. Moreover, at least one of the displacement electrode and the fixed electrode is constituted by a plurality of localized electrodes, and the change in the capacitance of the capacitance element formed by the localized electrodes is
It depends on the direction of the acting force and the location of the localized electrode. Therefore, the change in the capacitance of the plurality of capacitive elements formed by the plurality of localized electrodes includes information on the direction of the applied force. Therefore, the electrode forming surface is defined as an XY plane, and two groups of capacitive elements are formed on both the positive and negative sides of the X axis using two sets of localized electrodes. In this case, when a force in the X-axis direction acts on the acting body, the capacitance of both groups located on both the positive and negative sides of the X-axis changes complementarily. Directional forces can be detected. Further, when a force in the Z-axis direction acts on the acting body, the capacitance in the two groups changes in the same direction, so that the force in the Z-axis direction can be detected from the sum of these. Thus, force detection in the directions of the X axis and the Z axis can be performed.

(2) In the force detecting device according to the second aspect of the present invention, four groups of capacitive elements are formed by four sets of localized electrodes. When the electrode forming surface is defined as an XY plane, each group is formed on both the positive and negative sides of the X axis and the positive and negative sides of the Y axis. When a force in the X-axis direction acts on the acting body, the capacitances in both groups located on both the positive and negative sides of the X-axis change complementarily. Therefore, the force in the X-axis direction is calculated by the difference in capacitance between the two groups. Can be detected. Similarly, the force in the Y-axis direction can be detected from the difference in capacitance between the two groups located on both the positive and negative sides of the Y-axis. Thus, it is possible to detect a force in two directions of the X axis and the Y axis.

(3) In the force detection device according to the third aspect of the present invention, the force detection in the Z-axis direction can be further performed in the same electrode configuration as the above-described force detection device according to the second aspect. That is, when a force in the Z-axis direction is applied to the acting body, the capacitances of the four groups change in the same direction, so that the force in the Z-axis direction can be detected from the sum of the capacitances. Thus,
Force detection in three directions of X-axis, Y-axis and Z-axis becomes possible.

(4) In the force detecting device according to the fourth invention of the present application, the X-axis, Y-axis
In order to detect force in the three axes of the axis and the Z axis, totally independent dedicated electrodes are used. Thereby, the detection systems of the force components in each axial direction can be made independent.

(5) In the force detection device according to the fifth aspect of the present invention, when a predetermined voltage is applied between the electrodes, the flexible substrate can be displaced by Coulomb force acting between the electrodes. That is, it can be in a state equivalent to the state where an external force acts. If such a state can be created, it will be easy to test whether or not the device operates normally.

(6) In the force detecting device according to the sixth aspect of the present invention, the first auxiliary electrode and the displacement electrode are formed by a part of the flexible substrate. Therefore, it is not necessary to form a new electrode on the flexible substrate, so that the structure can be simplified and the manufacturing cost can be reduced.

(7) In the detecting device according to the seventh aspect of the present invention, a force generated based on the acceleration acting on the operating body is detected. Therefore, this detection value corresponds to the acceleration,
It can be used as an acceleration detection device.

(8) In the detecting device according to the eighth aspect of the present invention, a force generated based on a magnetic force acting on the working body made of a magnetic material is detected. Therefore, this detection value corresponds to magnetism, and can be used as a magnetism detection device.

〔Example〕

Hereinafter, the present invention will be described in detail 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.

Basic Embodiment FIG. 1 is a side sectional view showing the structure of an acceleration detecting device according to a basic embodiment of the present invention. The main components of this device are a fixed substrate 10, a flexible substrate 20, an operating body 30, and a device housing 40. FIG. 2 shows a bottom view of the fixed substrate 10. FIG. 1 shows a cross section of the fixed substrate 10 of FIG. 2 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. 3 shows a top view of the flexible substrate 20. FIG. 1 shows a cross section of the flexible substrate 20 of FIG. 3 cut along the X-axis. The flexible substrate 20 is also a disk-shaped substrate as shown in the figure, 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. 3, and is coaxially joined to the lower surface of the flexible substrate 20. The device housing 40 has a cylindrical shape and fixedly supports the periphery of the fixed substrate 10 and the flexible substrate 20.

The fixed substrate 10 and the flexible substrate 20 are provided at predetermined intervals at positions parallel to each other. Both are disc-shaped substrates, whereas the fixed substrate 10 is a substrate having high rigidity and hardly causing bending, whereas the flexible substrate 20 has flexibility and becomes a substrate that bends when a force is applied. I have. 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 to the right in FIG. 1, the Z axis is to the upper side, and the Y is
Axis, respectively.

Here, assuming that the entire device is mounted on, for example, an automobile, acceleration is applied to the operating body 30 based on the traveling of the automobile. Due to this acceleration, an external force acts on the action point P. In the state where no force acts on the action point P, the first
As shown in the figure, the fixed electrode 11 and the displacement electrodes 21 to 24 are kept parallel at a predetermined interval. However, for example, when a force Fx in the X-axis direction acts on the action point P, this force Fx
Fx generates a moment force on the flexible substrate 20, and the fourth
As shown in the drawing, the flexible substrate 20 is bent. 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 opposite bending occurs. On the other hand, when the force Fy or −Fy in the Y direction acts,
Similar changes occur in the distance between the displacement electrode 22 and the fixed electrode 11 and in the distance between the displacement electrode 24 and the fixed electrode 11. In addition, when a force Fz in the Z-axis direction is applied, as shown in FIG. 5, all of the displacement electrodes 21 to 24 come close to the fixed electrode 11, and when a force −Fz in the opposite direction is applied. Means that 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. 2 and the upper surface of the flexible substrate 20 shown in FIG. 3 are surfaces facing each other. Therefore, the facing relationship between the electrodes is the displacement electrodes 21 to 24.
Will face each opposing portion of the fixed electrode 11. In other words, while the fixed electrode 11 is a single common electrode, the displacement electrodes 21 to 24 are localized electrodes localized in a quadrant region. Even if the number of common electrodes is one, the four localized electrodes are electrically independent from each other, so that four groups of capacitive elements can be formed in terms of electrical characteristics. 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 capacitive 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, let the capacitance of each of these capacitance elements be C1, C2, C
It will be expressed as 3, 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
It is. However, as shown in FIG. 4 or FIG. 5, when a force acts on the point of action P and the flexible substrate 20 bends, the distance between the electrodes of each capacitance element changes, and the capacitance thereof also becomes a standard value. The value is different from C0. 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. 4, when a force Fx in the X-axis direction is applied to 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 from the electrode 11 is short, C3> C0. At this time, the distance between the displacement electrodes 22 and 24 and the fixed electrode 11 is partially close and partially distant, so that both parts cancel each other out, and the capacitance becomes C2 = C4 = C0. No change occurs. On the other hand, as shown in FIG.
When an axial force Fz is applied, the displacement electrodes 21 to 24 and the fixed electrode
The intervals with 11 are all close 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. 6 shows the capacitances C1 to C4 of the four groups of capacitance elements.
9 is a table showing a change pattern of C4. 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 decreases. Is shown. For example, the column of Fx in FIG. 6 shows changes in the capacitances C1 to C4 when the force Fx in the X-axis direction acts on the action point P, as shown in FIG. Thus, C1 becomes smaller, C3 becomes larger, and C2 and C4 remain unchanged.
Thus, based on the pattern of change of each capacitance,
The direction of the applied force can be recognized. 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. 7 shows a basic circuit for detecting the applied force for each axial component. The converters 51 to 54 are configured by circuits for converting the capacitances C1 to C4 of the respective capacitance elements into voltage values V1 to V4. For example, the capacitance C
May be converted to a frequency value f, and the frequency value f may be further converted to a voltage value V by a frequency / voltage conversion circuit. Of course, means for directly converting the capacitance value to the 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. 6, the X-axis direction component ± Fx is obtained by taking the difference between C1 and C3. 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 by referring to the columns of Fy and -Fy in FIG. 6, the Y-axis direction component ± Fy is obtained by taking the difference between C2 and C4. Further, the adder 57 is a circuit that calculates the sum of the voltage values V1 to V4 and outputs the sum as a Z-axis component ± Fz of the force to be detected. As can be understood by referring to the columns of Fz and -Fz in FIG. 6, the Z-axis direction component ± Fz is obtained by taking the sum of C1 to C4.

By applying predetermined wiring to each electrode shown in FIG. 2 and FIG. 3 according to the above principle and forming a detection circuit as shown in FIG. It can be detected as an electric signal for each 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.

Note that the detection circuit in FIG. 7 is shown as an example, and other circuits may be used. For example, CR
The capacitance value may be converted into a frequency value by using an oscillation circuit, and the converted value may be input to a microprocessor, and a three-dimensional acceleration may be obtained by digital operation.

Example showing Material of Each Part Next, the material of each part constituting the above-described force detection 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 is electrically insulated from each other.

(3) The flexible substrate is made of a material having flexibility.

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

The embodiment shown in FIG. 8 includes a fixed substrate 10a, a flexible substrate 20a,
This is an example in which a metal is used for all of the working bodies 30a. The flexible substrate 20a and the working body 30a are formed integrally. Of course, these may be made separately and then joined together. The device housing 40 is formed of, for example, metal, plastic, or the like, and is fixedly supported by fitting the periphery of each substrate into a support groove 41 formed on the inner surface. Since the fixed substrate 10a itself functions as the fixed electrode 11 as it is, the fixed electrode
It is not necessary to form 11 separately. The displacement electrodes 21a to 24a are
Since the flexible substrate 20a is made of metal, it cannot be formed directly thereon. Therefore, the displacement electrodes 21a to 24a are formed on the flexible substrate 20a via an insulating layer 25a made of a material such as glass or ceramic. In order to make the flexible substrate 20a flexible, its thickness may be reduced or it may be wavy to facilitate its deformation.

The embodiment shown in FIG. 9 includes a fixed substrate 10b, a flexible substrate 20b,
This is an example in which an insulator such as glass or ceramic is used for all of the action bodies 30b. The flexible 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 board 10b
A fixed electrode 11b made of metal is formed on the lower surface of the substrate, and displacement electrodes 21b to 24b made of metal are formed on the upper surface of the flexible substrate 20b.
Are formed. In order to make the flexible substrate 20b flexible, its thickness may be reduced, or a flexible synthetic resin may be used instead of glass or ceramic. Alternatively, deformation may be facilitated by partially providing a through hole.

The embodiment shown in FIG. 10 includes a fixed substrate 10c, a flexible substrate 20c,
This is an example in which a semiconductor such as silicon is used for all of the acting bodies 30c. The flexible substrate 20c and the working body 30c 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. The fixed electrode 11c located inside the lower surface of the fixed substrate 10c and the displacement electrodes 21c to 24c located inside the upper surface of the flexible substrate 20c are formed by diffusing impurities at a high concentration. In order to make the flexible substrate 20c flexible, the thickness may be reduced or a through hole may be provided partially.

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

Embodiment in which triaxial components are detected by independent electrodes In the above-described basic embodiment, a detection circuit as shown in FIG. 7 is shown. In this detection circuit, ± Fx or ± Fy
And the same capacitive element for detecting ± Fz is also used. In other words,
By using a single localized electrode, the two-axis directional components are detected. In the embodiment described here, the triaxial components are detected by completely independent dedicated electrodes. FIG. 11 shows a top view of a flexible substrate 20d used in this embodiment. Compared with the flexible substrate 20 in the basic embodiment shown in FIG. 3, the formation pattern of the localized electrodes is slightly 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 electrodes 21d and 21e arranged in the negative direction of the X axis, and the localized electrodes belonging to the second group are electrodes 22d arranged in the positive direction of the Y axis. Two
2e, the localized electrodes belonging to the third group are the electrodes 23d and 23e arranged in the positive direction of the X axis, and the localized electrodes belonging to the fourth group are arranged in the negative direction of the Y axis. Electrode 24d
And 24e.

Now, each of the four electrodes 21d to 24d hatched by dots in FIG. 11 and the fixed electrode
The capacitances of the four capacitive elements composed of the combination of 11 and C1 to C4, respectively, are hatched by hatching.
The electrostatic capacities of four capacitive elements formed of a combination of each of the two electrodes 21e to 24e and the fixed electrode 11 opposed thereto are denoted by C1 'to C4', respectively. Then, a detection circuit as shown in FIG. 12 is constituted by these eight capacitance elements. Here, the converters 51 to 54 convert the capacitances C1 to C4 into a voltage V1.
差動 V4, and the differential amplifiers 55 and 56 are circuits that amplify the difference between the two input voltage values and output the amplified voltage. Differential amplifiers 55 and 56 have ± Fx and ± Fy, respectively.
Is the same as that in the above-described basic embodiment. This embodiment is characterized by four capacitances C1 'to C1'.
4 'are connected in parallel, the converter 58 generates a voltage V5 corresponding to the sum of these, and outputs this as a detected value of ± Fz. When this detection principle is considered for the localized electrode shown in FIG. 11, ± Fx is detected by the electrodes 21d and 23d, ± Fy is detected by the electrodes 22d and 24d, and the electrode 21 is detected.
± Fz is detected by e, 22e, 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 example in which the electrodes 21e to 24e are each configured by an independent electrode has been described, but in fact, as is clear from the circuit diagram of FIG. 12, the capacitance element configured by the electrodes 21e to 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. 11, if the areas of the electrodes 21e, 22e, 23e, and 24e, which are hatched by oblique lines in the figure, are 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. 11 and the hatched area indicated by dots.

Embodiment in which the electrode forming pattern is changed In the above-described basic embodiment, as shown in FIG.
The fixed electrode 11 formed on the fixed substrate 10 is one common electrode, and the displacement electrodes formed on the flexible substrate 20 are four 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 are four localized electrodes, and the displacement electrodes formed on the flexible substrate 20 are one.
A single common electrode may be used. 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. The flexible substrate 20 shown in FIG.
Like f, only the 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, but it is possible to detect two-dimensional components composed of the X-axis direction component and the Z-axis direction component. Furthermore, if only one-dimensional detection is performed, it is only necessary to form one electrode on each of both substrates. Also,
The shape of the electrode is not limited to a circle or a sector, but may be any shape. Each substrate does not necessarily have to be disk-shaped.

Embodiment Having Test Function In general, when mass-producing some kind of detecting device and putting it on the market, an operation of confirming a normal detecting operation is performed in a test process before shipping. It is preferable that the above-described acceleration detection device be tested before shipment. 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. 14 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 flexible substrate 70,
5, the auxiliary substrate 80, and the device housing 40. In Figure 15,
FIG. 4 shows a bottom view of the fixed substrate 60. FIG. 14 shows a cross section of the fixed substrate 60 of FIG. 15 cut along the X-axis. The fixed substrate 60 is a metal disk-shaped substrate, and the periphery thereof is the device housing 40.
It is fixed to. On this lower surface, an insulating layer such as glass
Four quadrant-shaped fixed electrodes 61 to 64 are formed with the 65 interposed therebetween. The flexible substrate 70 is a flexible metal disk, and the periphery thereof is also fixed to the device housing 40. A columnar working body 75 is coaxially joined to the lower surface of the flexible substrate 70. The upper surfaces of the flexible 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. 16 shows a top view of the auxiliary substrate 80. FIG. FIG. 14 shows a cross section of the auxiliary substrate 80 of FIG. 16 cut along the X-axis. 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 a dashed line in FIG. 16, an operating body 75 is inserted into the central through hole. 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 flexible substrate 70 constitutes one auxiliary electrode facing the auxiliary electrodes 81 to 84. Thus, the flexible substrate 70
Is a metal lump integrally formed with the working body 75, the upper surface of which acts as one displacement electrode facing the fixed electrodes 61 to 64, and the lower surface thereof faces the auxiliary electrodes 81 to 84. Acts as one auxiliary electrode.

According to such a configuration, the fixed electrodes 61 to 64 and the displacement electrodes (the upper surface of the flexible substrate 70) facing the fixed electrodes 4
As described above, a set of capacitive elements can be formed, and the acceleration applied to the operating body 75 can be detected based on the change in the capacitance. Also, the auxiliary electrodes 81 to
Four sets of capacitive elements are formed by the displacement electrodes 84 and the displacement electrodes (the lower surface of the flexible substrate 70), and the acceleration can be detected. 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 flexible substrate 70
Will bend in a predetermined direction. For example, in FIG. 14, when voltages of different polarities are applied to the flexible substrate 70 and the electrode 63, an attractive force based on Coulomb force acts between the two, and a voltage of a different polarity is applied to the flexible substrate 70 and the electrode 81. Is applied, an attractive force based on the Coulomb force acts between them. If such an attractive force acts, the force in the X-axis direction as shown in FIG.
The flexible substrate 70 will bend in the same manner as when Fx acts. Also, if a voltage of the same polarity is applied to the flexible substrate 70 and the electrodes 81 to 84, a repulsive force based on Coulomb force acts between the two, and even if no force actually acts on the operating body 75, The flexible substrate 70 will bend in the same manner as when a force Fz in the Z-axis direction as shown in FIG. 5 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.

The structure to which the auxiliary substrate 80 is added as shown in FIG. 14 also has a secondary effect that the flexible substrate 70 can be prevented from being damaged when an excessive acceleration is applied. Although the flexible substrate 70 is flexible, it may be damaged when an excessive force is applied. However, according to the structure shown in FIG. 14, even when an excessive force is applied, the displacement of the flexible substrate 70 is limited to a predetermined range, so that no excessive displacement until damage occurs. That is, when excessive acceleration is applied in the lateral direction (X or Y axis direction) in FIG.
The side surface of the action body 75 abuts on the inner surface of the through hole of the auxiliary substrate 80, and the upper or lower surface of the bent flexible substrate 70 abuts on the fixed electrodes 61 to 64 or the auxiliary electrodes 81 to 84, and more. No displacement occurs. When excessive acceleration is applied in the vertical direction (Z-axis direction) in FIG.
The upper or lower surface of 70 is a fixed electrode 61 to 64 or an auxiliary electrode 81
8484, no further displacement occurs.

FIG. 17 is a side sectional view showing a state where the acceleration detecting device having the structure shown in FIG. Each electrode and the external terminals 91 to 93 are connected by bonding wires 94 to 96 (actually, electrically independent electrodes are connected to their own external terminals by their own bonding wires, respectively). However, only the main wiring is shown in the figure). 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.

Embodiment Using Piezoelectric Element In the various embodiments described above, since an external force is detected as a change in the capacitance value, a processing circuit for converting this capacitance value into a voltage value or the like is practically necessary. Become. The embodiment shown in FIG. 18 eliminates such a processing circuit by using a piezoelectric element. 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 flexible substrate 20f are mounted inside the device housing 40 so as to face each other. In this example,
Both substrates are insulators, but may be made of metal or semiconductor. When an external force acts on the working body 30f, the flexible substrate 2
0f is bent, and as a result, the distance between the fixed electrodes 11f, 12f and the variable 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 this purpose, the piezoelectric elements 101 and 102 are formed so as to be sandwiched between the fixed electrodes 11f and 12f and the variable electrodes 21f and 22f. When the distance between the two electrodes is reduced, the compressive force acts on the piezoelectric elements 101 and 102 when the electrode expands, and the tensile force acts on the piezoelectric elements 101 and 102. Therefore, 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 this may be mechanically connected between both electrodes. Although only the side cross section is shown in FIG. 18, three-dimensional acceleration can be detected by disposing four sets of piezoelectric elements as in the electrode arrangement shown in FIG. Alternatively, similarly to the electrode arrangement shown in FIG. 11, eight pairs (substantially, Z
(The four sets for detecting the force in the axial direction can be combined into one). Further, in order to detect two-dimensional acceleration, two sets of piezoelectric elements may be arranged in the same manner as the electrode arrangement shown in FIG. Specific device housing 40
In this case, the configuration is almost the same as that of the embodiment shown in FIG. 17, but the voltage values are directly output from the external terminals 91 to 93.

The secondary effect of the present embodiment shown in FIG.
Reference numeral 1,102 is a point having a protection function for the flexible substrate 20f.
That is, even when an excessive force is applied, the flexible 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.

Other Embodiments Although the present invention has been described based on some embodiments, the present invention is not limited to these embodiments, and can be implemented in various other modes. Especially,
In the above-described embodiment, the example in which the present invention is applied to the acceleration detecting device that detects the acceleration applied to the operating object has been described. However, the basic concept of the present invention is to detect the force acting on the operating object based on some physical phenomenon. The present invention is applicable to a device for directly detecting a force instead of an acceleration. FIG. 19 is a side sectional view of a force detection device having substantially the same structure as the acceleration detection 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 the acceleration detecting device shown in FIG. 17, 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, the force based on magnetism is applied to the operating body 75. Acts, it is possible to detect magnetism. As described above, the present invention is also applicable to a magnetic detection device.

〔The invention's effect〕

As described above, according to the force detection device of the present invention, the displacement electrode that is displaced by the force to be detected, and the fixed electrode that is fixed opposite thereto, the change in the capacitance of the capacitive element formed by Since the force is detected based on the above, a detection device capable of detecting a physical quantity such as force, acceleration, magnetism, etc. without performing temperature compensation can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a structure of an acceleration detecting device according to a basic embodiment of the present invention, FIG. 2 is a bottom view of a fixed substrate in the device shown in FIG. 1, and FIG. FIG. 4 is a side sectional view showing a state in which a force Fx in the X-axis direction is applied to the device shown in FIG. 1, and FIG. 5 is a sectional view showing the device shown in FIG. FIG. 6 is a side sectional view showing a state where an axial force Fz is applied, FIG. 6 is a table showing a principle of force detection in the device shown in FIG. 1, and FIG. 7 is a detection circuit applied to the device shown in FIG. FIG. 8 shows an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of a metal material, and FIG. 9 shows an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of an insulating material. FIG. 10 is a view showing an embodiment in which each substrate in the apparatus shown in FIG. 1 is made of a semiconductor material, and FIG. FIG. 12 is a top view of a flexible substrate of an acceleration detection device according to another embodiment of the invention, FIG. 12 is a detection circuit diagram for application to the device of the embodiment shown in FIG. 11, and FIG. Top view of the flexible substrate of the embodiment performing the detection,
FIG. 14 is a side sectional view showing a structure of an acceleration detecting device according to an embodiment having a test function, FIG. 15 is a bottom view of a fixed substrate in the device of FIG. 14, and FIG. 16 is a device in the device of FIG. FIG. 17 is a top view of the auxiliary substrate, FIG. 17 is a side sectional view showing a state where the acceleration detecting device having the structure shown in FIG. 14 is housed in a specific device housing 40, and FIG. 18 is an embodiment using a piezoelectric element. FIG. 19 is a side sectional view showing a structure, and FIG. 19 is a side sectional view of a force detecting device having substantially the same structure as the acceleration detecting device shown in FIG. 10 ... fixed substrate, 11 ... fixed electrode, 20 ... flexible substrate, 21
~ 24 ... displacement electrode, 25 ... insulating layer, 30 ... working body, 40 ...
... device housing, 41 ... support groove, 42 ... through hole, 51-54 ...
Converter, 55, 56 …… Differential amplifier, 57 …… Adder, 58 ……
Transducer, 60 …… Fixed substrate, 61-64 …… Fixed electrode, 65 ……
Insulating layer, 70 flexible substrate, 75 working body, 76 tentacle,
80 Auxiliary substrate, 81 to 84 Auxiliary electrode, 85 Insulating layer,
91-93: External terminals, 94-96: Bonding wires,
101, 102... Piezoelectric element, P...

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 1/14 G01P 15/125 G01L 5/16 G01R 33/02 WPI / L (QUESTEL)

Claims (8)

(57) [Claims] 1. A fixing portion fixed to a device housing, an operating portion to which an external force is transmitted, and a flexible portion formed between the fixing portion and the operating portion and having flexibility. And a fixed substrate fixed to the device housing so as to face the flexible substrate. An external force is received, and the force is transmitted to the operating portion of the flexible substrate. A displacement electrode formed on a surface of the flexible substrate facing the fixed substrate; and a fixed electrode formed on a surface of the fixed substrate facing the flexible substrate. Either one or both of the fixed electrodes are arranged at predetermined intervals along a predetermined axis on one electrode forming surface, and are constituted by two sets of electrically independent localized electrodes. A pair of localized electrodes, each of which comprises electrodes facing each other. Forming a group of capacitive elements, detecting the force of the predetermined axial component by a difference between the capacitances of the two groups of capacitive elements, and forming the electrode by the sum of the capacitive elements of the two groups. A force detecting device for detecting a force of an axial component orthogonal to a forming surface. A fixed portion fixed to the device housing, an operating portion to which an external force is transmitted, and a flexible portion formed between the fixed portion and the operating portion. And a fixed substrate fixed to the device housing so as to face the flexible substrate. An external force is received, and the force is transmitted to the operating portion of the flexible substrate. A displacement electrode formed on a surface of the flexible substrate facing the fixed substrate; and a fixed electrode formed on a surface of the fixed substrate facing the flexible substrate. Either one or both of the fixed electrodes, the first axis and the second axis orthogonal to each other on one electrode forming surface, when the intersection of both axes as the origin,
Each of the axes is arranged in the positive and negative directions, and is constituted by four sets of localized electrodes that are electrically independent of each other. Forming an element, detecting a force of the first axial component based on a difference between capacitances of capacitance elements belonging to two groups on the first axis among the four groups of capacitance elements, The force of the second axial component is detected based on a difference between the capacitances of the capacitance elements belonging to the two groups on the second axis among the capacitance elements of the four groups. Force detector. 3. The force detecting device according to claim 2, further comprising: a third axis orthogonal to both the first axis and the second axis by a sum of capacitances of the capacitance elements belonging to the four groups. A force detecting device for detecting a force of an axial component. 4. The force detecting device according to claim 2, further comprising a fifth set of localized electrodes electrically independent of the four sets of localized electrodes, and using the fifth set of localized electrodes. To form a fifth group of capacitive elements, and a third axial component force orthogonal to both the first axis and the second axis is detected by the capacitance of the fifth group of capacitive elements. A force detection device characterized in that: 5. The force detecting device according to claim 1, further comprising: an auxiliary substrate provided so that the fixed substrate, the flexible substrate, and the auxiliary substrate are arranged so as to face each other in this order. Forming a first auxiliary electrode on a surface of the flexible substrate facing the auxiliary substrate; forming a second auxiliary electrode on a surface of the flexible substrate facing the flexible substrate; A predetermined voltage is applied between the two electrodes or between the displacement electrode and the fixed electrode, and a displacement is generated in the flexible substrate by the Coulomb force acting between the two, so that the flexible substrate is brought into a state equivalent to an externally applied force. A force detection device characterized in that the force detection device can perform the force detection. 6. The force detecting device according to claim 5, wherein the flexible substrate is made of a conductive material, and the first auxiliary electrode and the displacement electrode are formed by a part of the conductive flexible substrate. A force detection device. 7. The detecting device according to claim 1, wherein the acceleration can be detected by detecting a force generated based on the acceleration acting on the operating body. Acceleration detection device. 8. The detecting device according to claim 1, wherein the working body is made of a magnetic material, and a force generated based on a magnetic force acting on the working body is detected, so that a magnetic force is generated. A magnetic detection device capable of performing detection.