JP7369585B2 - force sensor array - Google Patents

Description

The present invention relates to a force sensor array constituted by a plurality of force sensors using conductive members, particularly conductive members made of Cr-based thin films.

An in-plane pressure distribution sensor (surface pressure distribution sensor) consisting of a force sensor array detects, for example, the force on the sole of a person's feet when standing, on the seat of a chair when sitting on a chair, on the bed when lying down, etc. (Pressure) distribution measurements are being carried out. The force sensor used there is made of conductive rubber and is shaped like a thin, almost flat sheet. Although they can easily measure surface pressure distribution with good resolution, there are issues with the accuracy of measurement values, repeat durability, three-axis measurement (shear direction component detection), and load capacity during dynamic measurement. On the other hand, force sensors using a strain-generating structure such as a diaphragm include those in which a thin film sensor is formed on a MEMS element made of a silicon base material and a strain-generating body made of a metal such as stainless steel. The former has problems with load capacity and impact resistance, while the latter mainly uses strain gauges, but it is difficult to miniaturize, and in the case of conventional metal foil strain gauges, there is also a problem in increasing sensitivity.

The present inventor has proposed a conductive member configured of a Cr-based thin film made of Cr and unavoidable impurities or a Cr-based thin film made of Cr, N and unavoidable impurities (see Patent Document 1). These conductive members form strain sensors, and utilize the phenomenon that the electrical resistance of a sensor material in the form of a thin film, thin wire, or foil changes due to elastic strain, and by measuring the change in resistance, strain and It is used to measure and convert stress and various mechanical quantities. The sensitivity of the strain sensor is determined by the gauge factor Gf, and the value of Gf is generally given by the following relational expression (1).

Gf=(ΔR/R)/(Δl/l)
=1+2σ+(Δρ/ρ)/(Δl/l) (1).

Here, R, σ, and ρ are the total resistance, Poisson's ratio, and electrical specific resistance of the thin film, thin wire, or foil, which are the conductive members, respectively. Further, l is the total length of the object to be measured, and therefore Δl/l represents the strain occurring in the object to be measured. The gauge factor of Cr is large, and this is because the rate of change in resistivity Δρ/ρ, the last term on the right side of equation (1), changes significantly due to changes in the electronic structure due to strain. Even if the film is made thinner, the gauge factor is still large (it decreases depending on the film forming conditions), and if other elements are added, the gauge factor basically decreases, but if the amount added is small, it will not be the same as the conventional commercially available strained foil. Shows a gauge factor of 3 or more, which is larger than the gauge. Conversely, a conductive member made of Cr having a gauge factor of 3 or more or a conductive member made of Cr and/or a plurality of elements has a large change in specific resistance due to the above-mentioned change in the electronic structure of Cr. All such Cr-based thin films are intended as conductive members in the present invention. At the same time, a Cr-based thin film produced by sputtering etc. can have a horizontal sensitivity comparable to the longitudinal sensitivity (principal axis sensitivity) to strain as seen in Patent Document 1, which is due to the fact that the electronic structure This is because the change in (Δρ/ρ)/(Δl/l) in equation (1) caused by the change in is isotropic.

Therefore, this conductive member is arranged so that the longitudinal direction of the sensing part, which is the direction in which the measurement current flows, is perpendicular to the direction of strain on the object, and It has a gauge factor (3 or more) comparable to that in a case where the longitudinal direction of a certain sensing part is arranged parallel to the direction of strain of the object. In addition, the present inventor has proposed a conductive member composed of a Cr-based thin film made of Cr and Mn, a Cr-based thin film made of Cr and Al, and a Cr-based thin film made of Cr, Al, and N. (See Patent Documents 2 and 3).

Patent No. 6084393 JP2018091705A JP2018091848A

Conventional strain gauge-type diaphragm surface pressure distribution sensors use a radial arrangement of conductive members with longitudinal sensitivity, which increases the width (radial length) of the strain-generating part of the diaphragm element. Therefore, it has been difficult to miniaturize the diaphragm itself and to arrange multiple sensing sections within one element. Therefore, it is difficult to increase the density of elements (higher resolution) in distributed sensors, to achieve both weight reduction and higher load capacity, to detect components in the shear direction (in-plane direction), or to remove noise in the shear direction. Ta. In order to solve this problem, an object of the present invention is to provide a force sensor array that can expand the range of applications of a conductive member having isotropy in terms of gauge factor.

The present invention is characterized by using a conductive member consisting of a Cr-based thin film and a circumferential arrangement that takes advantage of its large lateral sensitivity, and can solve the above-mentioned problems. By using the circumferential (concentric circle) arrangement, the positional resolution of the conductive member is high enough to correspond to the extremely narrow line width that can be achieved with photolithography, so multiple conductors can be formed even in the extremely narrow strain-generating part of the strain-generating body. In addition, the diaphragm can be made smaller and the array can have higher resolution. In addition, the extremely narrow strain-generating part makes it possible to increase the load capacity of each strain-generating element, and furthermore, its high positional resolution allows the maximum value of strain to be used as it is, and in addition, the strain in each of the radial and circumferential directions can be used as is. Since it is possible to utilize the amount of strain that has been multiplied by superimposing them, a larger output can also be obtained. On the other hand, due to its high positional resolution, it is possible to construct conductive members arranged circumferentially in each of the four directions within the main surface of the strain-generating body, making it possible to accurately detect the shear direction (in-plane direction) component. be. Moreover, by having the conductive member take a shape that goes around the circumferential direction, the component in the in-plane direction can be canceled out, and only the Z component (component in the direction perpendicular to the plane) can be detected with high accuracy.

The force sensor array of the present invention includes a plurality of force sensors, a plurality of conducting wire members, and a resin member that fixes the plurality of force sensors and the plurality of conducting wire members in a designated arrangement manner. Each of the plurality of force sensors includes a flat plate-shaped strain body, a protrusion that transmits force to the strain body, and a support that supports the strain body continuously or discretely over the entire circumference. and a conductive member having an isotropic gauge factor in the direction of the main surface, the conductive member being disposed on at least one of the pair of main surfaces of the flexure element, A first strain amount in the meridian direction of the flexure element with reference to the pole when a force having at least one of a component perpendicular to the main surface and an in-plane component acts on the flexure element; In a specified latitude range in which the sum of the magnitudes of the second strain amounts in the latitude direction is greater than or equal to a reference value, the conductive member is attached to at least one main surface of the strain-generating body so as to extend in an arc shape in the latitude direction. The conductive wire member constitutes a strain detection circuit together with the conductive member, and the conductive member is a resistor whose electrical resistance value changes depending on the amount of strain of the flexure element. shall be.

According to the force sensor array having this configuration, in each force sensor, when a force acts on the protrusion directly or indirectly via the resin member, the force is transmitted from the protrusion to the strain body. Strain occurs in the strain-generating body. The designated latitude range is a latitude range in which the sum of the first strain amount in the meridian direction of the flexure body and the second strain amount in the latitude direction of the flexure body is equal to or greater than a reference value. Therefore, the amount of change in electrical resistance value between the end points of the conductive member in each force sensor is increased, the measurement accuracy of the force acting on the strain body is improved, and the force on the force sensor array including a plurality of force sensors is increased. The measurement accuracy of the mode of action is improved.

In the force sensor array of the present invention, a plurality of groups of the conductive members constituting each of the plurality of strain detection circuits are provided in each of a plurality of different specified longitude ranges of the strain body of each of the plurality of force sensors. It is preferable that each of them be arranged on the main surface of the strain body so as to extend in an arc shape in the latitude direction.

According to the force sensor array having this configuration, when a force is applied to the strain body through the protrusion, the distance between the end points of one or more conductive members constituting each group arranged in each designated longitude range Based on the electrical resistance value, it is possible to improve the accuracy of measuring the strain state of the strain body in each of the specified longitude ranges. Furthermore, by integrating the strain state of the flexure element in each designated longitude range, the principal plane direction component (or principal plane direction component and normal direction component) of the force acting on the flexure element through the protrusion is calculated. This improves the measurement accuracy of the force sensor array, and further improves the measurement accuracy of the manner in which force acts on a force sensor array including a plurality of force sensors.

In the force sensor array of the present invention, in the specified latitude range of the strain-generating body of each of the plurality of force sensors, the conductive member extends in an annular shape surrounding the polar point separated at one location. Preferably, it is arranged on the main surface of the flexure element.

According to the force sensor configured in this manner, when a force acts on the strain body through the protrusion, a vertical component is applied to the strain body at each of a pair of locations on opposite sides of the pole in the latitude range. The polarity of the strain generated when a force is applied is the same, while the polarity of the strain generated when a force in the direction of the principal surface is applied to the strain body is reversed. Therefore, at the pair of locations of the annularly extending conductive member separated at one location surrounding the pole, the electrical resistance value is determined according to the amount of strain that occurs when a vertical component of force acts on the strain-generating body. On the other hand, the changes in the electrical resistance value depending on the amount of strain that occur when a force in the direction of the principal surface is applied to the strain-generating body can be canceled out. Therefore, based on the amount of change in the electrical resistance value between the end points of the conductive member, the component in the principal plane direction of the force acting on the flexure element is at least partially removed, and the perpendicular component of the force can be measured with high accuracy. Therefore, it is possible to improve the accuracy of measuring the manner in which force acts on a force sensor array including a plurality of force sensors.

The shape of the strain body has rotational symmetry with respect to an axis parallel to a perpendicular line of the main surface passing through the pole point or mirror symmetry with respect to a plane perpendicular to the main surface passing through the pole point, and The continuous or discrete support mode by the support portion at the periphery of the flexure element has rotational symmetry with respect to the axis or mirror symmetry with respect to the plane, and the conductive member It is preferable that the strain-generating body is disposed on the principal surface of the strain body so as to have rotational symmetry with respect to an axis or mirror symmetry with respect to the plane.

When the conductive member is composed of a Cr-based thin film (deposited film), the electrical resistance of the conductive member is due to the lattice structure of the conductive member, rather than the contribution to shape change due to longitudinal strain and transverse strain. Furthermore, since it changes greatly depending on the contribution of carriers (electrons) to changes in the band energy structure, it is possible to further improve the measurement accuracy of the normal component of the force acting on the strain body.

FIG. 1 is a schematic explanatory diagram of a force sensor array according to a first embodiment of the present invention. FIG. 1 is an explanatory diagram regarding the configuration of a force sensor array as a first embodiment of the present invention. FIG. 4 is an explanatory diagram regarding the arrangement of conductive members of the force sensor according to the first embodiment. 4 is a cross-sectional view of the force sensor taken along line IV-IV in FIG. 3. FIG. FIG. 3 is an explanatory diagram regarding the configuration of the strain body of the first embodiment. FIG. 4 is an explanatory diagram regarding a first strain mode of the flexure element of the first embodiment. FIG. 6 is an explanatory diagram regarding a second strain mode of the flexure element of the first embodiment. FIG. 7 is an explanatory diagram regarding a third strain mode of the flexure element of the first embodiment. FIG. 7 is an explanatory diagram regarding the configuration of the strain body of the second embodiment. FIG. 7 is an explanatory diagram regarding the first strain mode of the flexure element of the second embodiment. FIG. 7 is an explanatory diagram regarding a second strain mode of the flexure element of the second example. FIG. 7 is an explanatory diagram regarding a third strain mode of the flexure element of the second embodiment. FIG. 7 is an explanatory diagram regarding the configuration of the strain body of the third embodiment. FIG. 7 is an explanatory diagram regarding the first strain mode of the flexure element of the third embodiment. FIG. 7 is an explanatory diagram regarding a second strain mode of the flexure element of the third embodiment. FIG. 7 is an explanatory diagram regarding a third strain mode of the flexure element of the third embodiment. FIG. 2 is an illustrative diagram of a strain sensing circuit in one embodiment. FIG. 7 is an explanatory diagram regarding the configuration of a force sensor array according to a second embodiment of the present invention. FIG. 7 is an explanatory diagram regarding the arrangement of conductive members of a force sensor according to another embodiment. FIG. 6 is an explanatory diagram regarding the function of the force sensor according to the first force application mode. FIG. 7 is an explanatory diagram regarding the function of the force sensor according to the second force application mode. FIG. 7 is an explanatory diagram regarding the function of the force sensor according to the third force application mode.

(composition)
A force sensor array according to a first embodiment of the present invention shown in FIGS. 1 and 2 includes a plurality of force sensors 1, a plurality of conductor members 2, a plurality of force sensors 1 and a plurality of conductor members 2. and a resin member 3 for fixing. For example, the plurality of force sensors 1 are arranged in a square grid on the same plane. In the force sensor 1, the upper part of the protrusion 11 is exposed by protruding from the upper end surface of the resin member 3, while the remaining part is embedded in the resin member 3.

The plurality of force sensors 1 may be arranged on the same plane according to other regular arrangement patterns such as a triangular lattice shape or radial arrangement, or may be arranged according to an irregular arrangement arrangement. The plurality of force sensors 1 may be arranged not on the same plane, but on each of a plurality of planes, or on the same curved surface.

As shown in FIG. 3, the force sensor 1 includes a strain body 10 (straight body) and conductive members 211 to 218 and 221 to 228. When the conductive members 211 to 218 and 221 to 228 are not distinguished from each other, they are expressed as "conductive members 20." In order to explain the positions and postures of the components of the force sensor, a three-dimensional orthogonal coordinate system (X, Y, Z) whose origin is the center point of the first principal surface 101 of the strain body 10 will be used.

The strain-generating body 10 has a thickness direction in the Z direction, and is formed into a substantially disk shape having a pair of principal surfaces, a first principal surface 101 and a second principal surface 102, which are substantially parallel to the XY plane. The strain body 10 is made of, for example, an elastic metal, a synthetic resin, or a combination thereof. When the strain body 10 is made of a conductive material such as metal, its first main surface 101 is covered with an insulating thin film 18 at least in the region where the conductive member 20 is formed. Thereby, the strain body 10 and the conductive member 20 are electrically insulated.

The thickness of the strain-generating body 10 may be uniform, or may be non-uniform as in the case where there are locally thinned regions. The shape of the strain body 10 has rotational symmetry with respect to an axis (z-axis) parallel to the perpendicular to the first main surface 101 passing through the pole point O, or a plane perpendicular to the first main surface 101 passing through the pole point O (e.g. , xz plane) as a reference.

For reliable strain generation in the strain body 10, openings communicating with the gap between the strain body 10 and the resin member 3 or the external space of the resin member 3 may be provided above and below the strain body 10.

As shown in FIGS. 3 and 4, the force sensor 1 includes a substantially cylindrical protrusion 11 protruding from the center of the second main surface 102 of the strain body 10. As shown in FIGS. The protruding portion 11 may have various shapes such as a substantially prismatic shape, a substantially conical shape, a substantially pyramidal shape, a substantially truncated cone shape, or a substantially truncated pyramid shape. The strain body 10 and the protrusion 11 are integrally formed structures by cutting and/or casting. The protruding portion 11 may be joined to the strain body 10 by a mechanical method such as a bolt-and-nut method, or a joining method such as adhesion or welding. The protrusion 11 may be spaced apart from the flexure element 10, and a portion of the resin member 3 may be interposed between the second main surface 102 of the flexure element 10 and the lower end of the protrusion 11.

The upper end height position (Z coordinate value) of the protruding portion 11 is higher than the upper end height position of the support portion 12 (see FIG. 4). The height position of the upper end of the protruding part 11 may be the same as the height position of the upper end of the support part 12, or may be lower than the height position of the upper end of the support part 12.

The protrusion 11 may be swingably supported relative to the flexure element 10 by the lower end of the protrusion 11 entering the recess of the flexure element 10 . In this case, for example, a concave portion recessed downward from the second main surface 102 of the flexure element 10 in a substantially spherical crown shape is formed, and the protrusion 11 is formed in the recess formed on the second main surface 102 of the flexure element 10. It has a substantially spherical lower end corresponding to the spherical shape. The shape of the lower end of the protrusion 11 may be changed to various shapes, such as a substantially cylindrical shape or a truncated cone shape, in which the tip edge is chamfered over the entire circumference.

The strain body 10 is fixed or supported over its entire circumference by a substantially annular support portion 12 that protrudes from the peripheral edge of its second main surface 102 . The strain body 10 and the support portion 12 are integrally formed structures by cutting and/or casting. The support portion 12 may be joined to the strain body 10 by a mechanical method such as a bolt-and-nut method, or a joining method such as adhesion or welding. The continuous support mode by the support portion 12 at the peripheral edge of the strain-generating body 10 has rotational symmetry with respect to the axis (which may be different from the rotational symmetry) or a mirror image with respect to the plane. It has symmetry.

The lower end height position (Z coordinate value) of the support portion 12 is the same as the height position of the first main surface 101 of the strain body 10 (see FIG. 4). The height position of the upper end of the support portion 12 may be lower than the height position of the first main surface 101 of the strain body 10.

Here, as shown in FIG. 5, a disk-shaped SUS316L (Young's modulus: 193 GPa, Poisson's ratio: 0.28) with a thickness of 0.1 mm and a radius of 2.0 mm is assumed as the strain-generating body 10. It was done. As the protrusion 11, SUS316L with a height of 0.8 mm and a radius of 0.5 mm was assumed. As the support part 12, SUS316L with a height of 0.5 mm, an inner diameter of 3.0 mm, and an outer diameter of 4.0 mm was assumed. When a force of 100 N is applied to the upper end of the protrusion 11 in the Z direction (thickness direction of the disc), The strain in each of the 0.05 mm meshes was calculated according to the finite element method.

FIG. 6A shows a calculation of the strain characteristics on the first principal surface 101 of the strain body 10 when a force is locally applied to the strain body 10 in the perpendicular direction (Z direction) through the protrusion 11. Results are shown. The manner in which the "first strain amount" changes in the meridian direction or the radial direction from the pole point O to the point fixed by the support part 12 is shown by a broken line, and the change mode in the latitudinal direction or circumferential direction is The change mode of the "second strain amount" which is the strain amount of the flexure element 10 is shown by a dashed-dotted line, and the composite value (sum) of both is shown by a solid line. A "negative" amount of strain represents the amount of contraction of the strain-generating body 10 (more precisely, the first principal surface 101 (the surface opposite to the stress loading side)), while a "positive" strain amount represents the amount of contraction of the strain-generating body 10. 10 (same as above).

The first strain amount and the second strain amount in the annular negative strain designated latitude range R _- within a distance of 0.68D to 0.76D from the pole O based on the meridian length D (radius 2 mm here). The sum is "negative" and is less than or equal to the reference value. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the designated negative strain latitude range R _- is a distance range of 0.62D to 0.79D from the pole O. Here, the latitude range within a distance of 0.25D from the pole O corresponds to the region in which the protrusion 11 exists, and the latitude range within a distance of 0.75 to 1.0D from the pole O corresponds to the region in which the support part 12 exists.

The sum of the first strain amount and the second strain amount is "positive" in the annular positive strain specified latitude range R ₊ in the range of distance 0.23D to 0.31D from the pole O based on the length D of the meridian. Yes, and above the standard value. The positive strain specified latitude range R ₊ is surrounded by the negative strain specified latitude range R _- . The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the positive strain amount, the positive strain specified latitude range R ₊ is a distance range of 0.21D to 0.38D from the pole O.

FIG. 6B shows the state of the strain body 10 when a force of 20 N is locally applied to the strain body 10 through the protrusion 11 in, for example, the +Y direction of its main surface direction (shear direction). Calculation results of strain characteristics along a line segment (X=0, -D≦Y≦D) on the first principal surface 101 are shown. "D" is the length of the radial line (here, the radius is 2 mm). The display method and the like are the same as in FIG. 6A.

The sum of the first strain amount and the second strain amount is “positive” in the first positive strain specified latitude range {0.70D≦Y≦0.75D} along the line segment, and is equal to or greater than the reference value. be. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the positive strain amount, the first positive strain specified latitude range along the line segment is {0.66D≦Y≦0.79D}. Here, the latitude range within a distance of 0.25D from the pole O corresponds to the region in which the protrusion 11 exists, and the latitude range within a distance of 0.75 to 1.0D from the pole O corresponds to the region in which the support part 12 exists.

Further, the sum of the first strain amount and the second strain amount is “negative” in the first negative strain specified latitude range {-0.75D≦Y≦-0.70D} along the line segment, and It is below the standard value. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the first specified negative strain latitude range along the line segment is {-0.79D≦Y≦-0.66D}.

Furthermore, the sum of the first strain amount and the second strain amount is "negative" in the second negative strain specified latitude range {0.25D≦Y≦0.29D} along the line segment, and the reference value It is as follows. The second designated negative strain latitude range is closer to the pole O than the first designated positive strain latitude range. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the second negative strain designated latitude range along the line segment is {0.20D≦Y≦0.37D}.

Further, the sum of the first strain amount and the second strain amount is “positive” in the second positive strain specified latitude range {-0.29D≦Y≦-0.25D} along the line segment, and It is above the standard value. The second positive strain specified latitude range is closer to the pole O than the first negative strain specified latitude range. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the amount of positive strain, the second positive strain specified latitude range along the line segment is {-0.37D≦Y≦-0.20D}.

That is, the strain characteristics along the line segment (X=0, -D≦Y≦D) on the first principal surface 101 of the strain-generating body 10 are such that the sign is reversed with respect to the pole point O. In addition, if a force in the opposite direction, for example, a force in the -Y direction, acts in the same principal surface direction, in each specified range of the first positive strain, first negative strain, second negative strain, and second positive strain. Although the sign of the resulting strain is opposite to that when a force in the +Y direction is applied, it is still a characteristic in which the sign is reversed with respect to the pole point O.

FIG. 6C shows the first part of the strain body 10 when a force is locally applied to the strain body 10 in the +Y direction of the main surface direction (shear direction) through the protrusion 11. Calculation results of strain characteristics along a line segment (0≦X≦D, Y=0) on the main surface 101 are shown. The display method and the like are the same as in FIG. 6A.

It can be seen from FIG. 6C that only a very small strain occurs in the strain body 10 from the pole point O to the support portion 12. Due to the symmetry, the calculation results of the strain characteristics along the line segment (-D≦X≦0, Y=0) are also similar, and therefore, there is a strain-generating body in the direction perpendicular to the direction in which the force acts in the principal plane direction. It is confirmed that almost no distortion occurs in 10.

On the first main surface 101 of the flexure element 10, the conductive member 20 extends in an annular shape divided at one point and has mirror symmetry with respect to a plane passing through the pole O and perpendicular to the first main surface 101. According to the force sensor arranged in such a manner, the component of the force in the principal plane direction is not detected due to the strain characteristics shown in FIG. 6B, and only the vertical component is detected with high accuracy. Therefore, it is preferable that the conductive member 20 is arranged so as to be included in the specified negative strain latitude range R _- and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (Fig. (See 6A).

A force sensor in which conductive members 20 are arranged to extend in the circumferential direction in each of four azimuth ranges having the same circumferential angle with respect to the pole O on the first main surface 101 of the strain body 10. In this case, triaxial force sensing is possible. Therefore, the conductive member 20 is at least partially included in the specified negative strain latitude range R ₋ and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (see FIG. 6A); In addition, a first positive strain designated latitude range, a second positive strain designated latitude range, a first negative strain designated latitude range, and a second designated latitude range allow for accurate detection of force in the shear direction (principal surface direction) along any latitude line. It is preferable that the negative strain extends so as to intersect or perpendicularly intersect with the latitude in at least one of the specified latitude ranges (see FIG. 6B).

As shown in FIG. 7, a disk-shaped SUS316L (Young's modulus: 193 GPa, Poisson's ratio: 0.28) with a thickness of 0.4 mm and a radius of 2.0 mm was assumed as the strain-generating body 10. As the protrusion 11, SUS316L with a height of 0.5 mm and a radius of 1.0 mm was assumed. As the support part 12, SUS316L with a height of 0.2 mm, an inner diameter of 3.0 mm, and an outer diameter of 4.0 mm was assumed. When a force of 1000 N is applied to the upper end of the protrusion 11 in the Z direction (thickness direction of the disk), The strain in each of the 0.05 mm meshes was calculated according to the finite element method.

FIG. 8A shows the strain generated when a force is locally applied in the perpendicular direction to the strain body 10 through the protrusion 11 in the strain body 10 having the shape and dimensions shown in FIG. Calculation results of strain characteristics on the first principal surface 101 of the body 10 are shown. The display method and the like are the same as in FIG. 6A.

The first strain amount and the second strain amount in the annular negative strain designated latitude range R _- within a distance of 0.98D to 1.0D from the pole O based on the meridian length D (here, the radius is 2 mm). The sum is "negative" and is less than or equal to the reference value. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the designated negative strain latitude range R _- is a distance range of 0.77D to 1.0D from the pole O. Here, the latitude range within a distance of 0.5D from the pole O corresponds to the region where the protrusion 11 exists, and the latitude range from the pole O to a distance of 0.75 to 1.0D corresponds to the region where the support portion 12 exists.

The sum of the first strain amount and the second strain amount is "positive" in the annular positive strain specified latitude range R ₊ in the range of distance 0.30D to 0.53D from the pole O based on the length D of the meridian. Yes, and above the standard value. The positive strain specified latitude range R ₊ is surrounded by the negative strain specified latitude range R _- . The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the positive strain amount, the positive strain specified latitude range R ₊ is a distance range of 0D to 0.58D from the pole O.

FIG. 8B shows the state of the flexure element 10 when a force of 200 N is locally applied to the flexure element 10 through the protrusion 11 in, for example, the +Y direction of its main surface direction (shear direction). Calculation results of strain characteristics along a line segment (X=0, -D≦Y≦D) on the first principal surface 101 are shown. "D" is the length of the radial line (here, the radius is 2 mm). The display method and the like are the same as in FIG. 6A.

In the first positive strain specified latitude range {0.98D≦Y≦D} along the line segment, the sum of the first strain amount and the second strain amount is “positive” and is greater than or equal to the reference value. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum positive strain amount, the first positive strain specified latitude range along the line segment is {0.86D≦Y≦D}. Here, the latitude range within a distance of 0.5D from the pole O corresponds to the region where the protrusion 11 exists, and the latitude range from the pole O to a distance of 0.75 to 1.0D corresponds to the region where the support portion 12 exists.

In addition, the sum of the first strain amount and the second strain amount is “negative” in the first negative strain specified latitude range {-D≦Y≦-0.98D} along the line segment, and the reference value It is as follows. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the first negative strain specified latitude range along the line segment is {-D≦Y≦-0.86D}.

Furthermore, the sum of the first strain amount and the second strain amount is “negative” in the second negative strain specified latitude range {0.41D≦Y≦0.54D} along the line segment, and the reference value It is as follows. The second designated negative strain latitude range is closer to the pole O than the first designated positive strain latitude range. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the second negative strain designated latitude range along the line segment is {0.33D≦Y≦0.60D}.

Further, the sum of the first strain amount and the second strain amount is "positive" in the second positive strain specified latitude range {-0.54D≦Y≦-0.41D} along the line segment, and It is above the standard value. The second positive strain specified latitude range is closer to the pole O than the first negative strain specified latitude range. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the amount of positive strain, the second positive strain specified latitude range along the line segment is {-0.60D≦Y≦-0.33D}.

That is, the strain characteristics along the line segment (X=0, -D≦Y≦D) on the first principal surface 101 of the strain-generating body 10 are such that the sign is reversed with respect to the pole point O.

FIG. 8C shows the first part of the strain body 10 when a force is locally applied to the strain body 10 in the +Y direction of the main surface direction (shear direction) through the protrusion 11. Calculation results of strain characteristics along a line segment (0≦X≦D, Y=0) on the main surface 101 are shown. The display method and the like are the same as in FIG. 6A.

It can be seen from FIG. 8C that only a very small strain occurs in the strain body 10 from the pole point O to the support portion 12. Due to the symmetry, the calculation results of the strain characteristics along the line segment (-D≦X≦0, Y=0) are also similar, and therefore, there is a strain-generating body in the direction perpendicular to the direction in which the force acts in the principal plane direction. It is confirmed that almost no distortion occurs in 10.

On the first main surface 101 of the flexure element 10, the conductive member 20 extends in an annular shape divided at one point and has mirror symmetry with respect to a plane passing through the pole O and perpendicular to the first main surface 101. According to the force sensor arranged in such a manner, the component of the force in the principal plane direction is not detected due to the strain characteristics shown in FIG. 8B, and only the vertical component is detected with high accuracy. Therefore, it is preferable that the conductive member 20 is arranged so as to be included in the specified negative strain latitude range R _- and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (Fig. (See 8A).

A force sensor in which conductive members 20 are arranged to extend in the circumferential direction in each of four azimuth ranges having the same circumferential angle with respect to the pole O on the first main surface 101 of the strain body 10. In this case, triaxial force sensing is possible. Therefore, the conductive member 20 is at least partially included in the specified negative strain latitude range R _- and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (see FIG. 8A), In addition, a first positive strain designated latitude range, a second positive strain designated latitude range, a first negative strain designated latitude range, and a second designated latitude range allow for accurate detection of force in the shear direction (principal surface direction) along any latitude line. It is preferable that the negative strain extends so as to intersect the latitude in at least one of the specified latitude ranges (see FIG. 8B).

As shown in FIG. 9, a disk-shaped SUS316L (Young's modulus: 193 GPa, Poisson's ratio: 0.28) with a thickness of 0.2 mm and a radius of 2.0 mm was assumed as the strain-generating body 10. As the protrusion 11, SUS316L with a height of 0.7 mm and a radius of 1.0 mm was assumed. As the support part 12, SUS316L with a height of 0.4 mm, an inner diameter of 3.0 mm, and an outer diameter of 4.0 mm was assumed. When a force of 1000 N is applied to the upper end of the protrusion 11 in the Z direction (thickness direction of the disk), The strain in each of the 0.05 mm meshes was calculated according to the finite element method.

FIG. 10A shows the strain generated when a force is locally applied in the perpendicular direction to the strain body 10 through the protrusion 11 in the strain body 10 having the shape and dimensions shown in FIG. Calculation results of strain characteristics on the first principal surface 101 of the body 10 are shown. The display method and the like are the same as in FIG. 6A.

The first strain amount and the second strain amount in the annular negative strain designated latitude range R _- within a distance of 0.71D to 0.80D from the pole O based on the meridian length D (radius 2 mm here). The sum is "negative" and is less than or equal to the reference value. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the designated negative strain latitude range R _- is a distance range of 0.68D to 0.86D from the pole O. Here, the latitude range within a distance of 0.5D from the pole O corresponds to the region where the protrusion 11 exists, and the latitude range from the pole O to a distance of 0.75 to 1.0D corresponds to the region where the support portion 12 exists.

The sum of the first strain amount and the second strain amount is "positive" in the annular positive strain specified latitude range R ₊ in the range of distance 0.44D to 0.54D from the pole O with the length D of the meridian as a reference. Yes, and above the standard value. The positive strain specified latitude range R ₊ is surrounded by the negative strain specified latitude range R _- . The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the positive strain amount, the specified positive strain latitude range R ₊ is a distance range of 0.38D to 0.58D from the pole O.

FIG. 10B shows the state of the flexure element 10 when a force of 200 N is locally applied to the flexure element 10 through the protrusion 11 in, for example, the +Y direction of its main surface direction (shear direction). Calculation results of strain characteristics along a line segment (X=0, -D≦Y≦D) on the first principal surface 101 are shown. "D" is the length of the radial line (here, the radius is 2 mm). The display method and the like are the same as in FIG. 6A.

The sum of the first strain amount and the second strain amount is “positive” in the first positive strain specified latitude range {0.72D≦Y≦0.80D} along the line segment, and is equal to or greater than the reference value. be. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the amount of positive strain, the first positive strain specified latitude range along the line segment is {0.70D≦Y≦D}. Here, the latitude range within a distance of 0.5D from the pole O corresponds to the region where the protrusion 11 exists, and the latitude range from the pole O to a distance of 0.75 to 1.0D corresponds to the region where the support portion 12 exists.

Further, the sum of the first strain amount and the second strain amount is "negative" in the first negative strain specified latitude range {-0.80D≦Y≦-0.72D} along the line segment, and It is below the standard value. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the first negative strain specified latitude range along the line segment is {-D≦Y≦-0.70D}.

Furthermore, the sum of the first strain amount and the second strain amount is "negative" in the second negative strain specified latitude range {0.47D≦Y≦0.53D} along the line segment, and the reference value It is as follows. The second designated negative strain latitude range is closer to the pole O than the first designated positive strain latitude range. The reference value was set as 80% of the minimum value for negative strain amounts. When the reference value is set to 50% of the minimum value of the amount of negative strain, the second negative strain designated latitude range along the line segment is {0.41D≦Y≦0.58D}.

Further, the sum of the first strain amount and the second strain amount is “positive” in the second positive strain specified latitude range {-0.53D≦Y≦-0.47D} along the line segment, and It is above the standard value. The second positive strain specified latitude range is closer to the pole O than the first negative strain specified latitude range. The reference value was set as 80% of its maximum value for positive strain amounts. When the reference value is set to 50% of the maximum value of the amount of positive strain, the second positive strain specified latitude range along the line segment is {-0.58D≦Y≦-0.41D}.

That is, the strain characteristics along the line segment (X=0, -D≦Y≦D) on the first principal surface 101 of the strain-generating body 10 are such that the sign is reversed with respect to the pole point O.

FIG. 10C shows the first part of the strain body 10 when a force is locally applied to the strain body 10 in the +Y direction of the main surface direction (shear direction) through the protrusion 11. Calculation results of strain characteristics along a line segment (0≦X≦D, Y=0) on the main surface 101 are shown. The display method and the like are the same as in FIG. 6A.

It can be seen from FIG. 10C that only a very small strain occurs in the strain body 10 from the pole point O to the support portion 12. Due to the symmetry, the calculation results of the strain characteristics along the line segment (-D≦X≦0, Y=0) are also similar, and therefore, there is a strain-generating body in the direction perpendicular to the direction in which the force acts in the principal plane direction. It is confirmed that almost no distortion occurs in 10.

On the first main surface 101 of the flexure element 10, the conductive member 20 extends in an annular shape divided at one point and has mirror symmetry with respect to a plane passing through the pole O and perpendicular to the first main surface 101. According to the force sensor arranged in such a manner, the component of the force in the principal plane direction is not detected due to the strain characteristics shown in FIG. 10B, and only the vertical component is detected with high accuracy. Therefore, it is preferable that the conductive member 20 is arranged so as to be included in the specified negative strain latitude range R _- and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (Fig. 10A).

A force sensor in which conductive members 20 are arranged to extend in the circumferential direction in each of four azimuth ranges having the same circumferential angle with respect to the pole O on the first main surface 101 of the strain body 10. In this case, triaxial force sensing is possible. Therefore, the conductive member 20 is at least partially included in the specified negative strain latitude range R ₋ and/or the specified positive strain latitude range R ₊ when a force is applied locally in the perpendicular direction (see FIG. 10A), and a first positive strain specified latitude range, a second positive strain specified latitude range, a first negative strain specified latitude range, and a second negative strain specified latitude range, in which the force in the shear direction (principal surface direction) can be detected with high accuracy. It is preferable that it extends so as to intersect at least one of them (see FIG. 10B).

As shown in FIG. 3, in the latitude range R _- where negative strain is specified on the first principal surface 101 of the strain body 10, there are eight longitude ranges [45(n-1)°+δ, 45n°-δ]( Conductive members 211 to 218 each having a substantially arc shape extending in the latitude direction are arranged at each of the positions where n=1 to 8) (δ is, for example, 1° to 5°). Each of the conductive members 211 to 218 may be arranged so as to be outside the region where the protrusion 11 exists, or may be arranged so as to be included in the region where the protrusion 11 exists.

In the positive strain specified latitude range R ₊ of the first principal surface 101 of the flexure element 10, substantially arc-shaped conductive members 221 to 228 extending in the latitude direction are arranged in each of the eight longitude ranges. There is. Each of the conductive members 221 to 228 may be arranged so as to be outside the region where the support section 12 exists, or may be arranged so as to be included in the region where the support section 12 exists.

The conductive member 20 is formed on the first main surface 101 of the strain body 10 . The conductive member 20 has isotropy in terms of gauge factor (gauge factor is 3 or more), and is made of, for example, a Cr thin film made of Cr and inevitable impurities described in Patent Document 1, or Cr , N and inevitable impurities. The Cr--N thin film is, for example, represented by the general formula Cr _100-x N _x , and the composition ratio x is 0.0001≦x≦30 in atomic %.

The conductive member 20 has a general formula Cr _100-x Mn _x (x is atomic % and 0.1≦x≦34) or a general formula Cr _100-x Al _x (x is atomic % and 4 ≦x≦25) (see Patent Document 2). The conductive member 20 is a Cr-based thin film represented by the general formula Cr _100-xy Al _x N _y (x, y are atomic %, and 4≦x≦25, 0.1≦y≦20). (See Patent Document 3). The conductive member 20 is made of a Cr-based thin film other than the above ( It may be formed of a thin film containing one or more elements in Cr and a small amount of other elements. The thin film is formed on the first main surface 101 of the strain body 10 or the insulating thin film 18 by sputtering or the like. The Cr--N thin film has an extremely small temperature coefficient of resistance (TCR) (<±50 ppm/° C.) and is therefore stable against temperature changes.

Each of the plurality of conducting wire members 2 is connected to both ends of the conductive member M (M=211 to 218, 221 to 228) via electrode terminals M- and M+, respectively. "M-" represents the electrode terminal on the low longitude side (the side where the azimuth angle (0° to 360°) is small) of the conductive member M, and "M+" represents the electrode terminal on the high longitude side (the side where the azimuth angle is large) of the conductive member M. side) represents the electrode terminal.

Among the conductive wire members 2, the "first conductive wire member group" includes four active conductive members 218, 211, 228, and 221 located in the first specified longitude range [-45° (=315°), 45°]. It is embedded in the resin member 3 so as to constitute the "first bridge circuit" of the gauge method (see FIG. 11). Among the conductive wire members 2, the "second conductive wire member group" is the "second conductive wire member group" of the 4 active gauge method together with the conductive members 212, 213, 222, and 223 arranged in the second specified longitude range [45°, 135°]. It is embedded in the resin member 3 so as to constitute a bridge circuit. Among the conductive wire members 2, the "third conductive wire member group" is the "third conductive wire member group" of the 4 active gauge method along with the conductive members 214, 215, 224, and 225 arranged in the third specified longitude range [135°, 225°]. It is embedded in the resin member 3 so as to constitute a bridge circuit. Among the conductive wire members 2, the "fourth conductive wire member group" is the "fourth conductive wire member group" of the four active gauge method together with the conductive members 216, 217, 226, and 227 arranged in the fourth specified longitude range [225°, 315°]. It is embedded in the resin member 3 so as to constitute a bridge circuit. In the four-active gauge method used here, a three-wire system may be used in addition to the two-wire system.

The thickness, width, length, and electrical properties of the conductive member 20, such as electrical conductivity, are appropriately designed from the viewpoint of forming a bridge circuit (strain detection circuit). The thickness, width, length, and material (which determines electrical conductivity) of the conductive wire member 2 are appropriately designed from the viewpoint of constructing the bridge circuit, similarly to the conductive member 20.

(function)
According to the force sensor array as an embodiment of the present invention, in each force sensor 1, when force acts on the protrusion 11 directly or indirectly via the resin member 3, the force from the protrusion 11 causes the strain body 10 to The force is transmitted to the strain body 10, causing strain in the strain body 10.

The designated latitude ranges R ₊ and R ₋ in which the conductive member 20 is arranged are the magnitudes of the first strain amount in the meridian direction of the flexure body 10 and the second strain amount in the latitude direction of the flexure body 10 . This is the latitude range where the sum is equal to or greater than the reference value (see FIG. 5). Based on the electrical resistance value between the end points of the plurality of conductive members 20 constituting each of the first to fourth conductive member groups arranged in the first to fourth designated longitude ranges, each of the designated longitude ranges is The accuracy of measuring the strain state of the strain-generating body 10 can be improved.

The difference between the X-direction component F _x (component in the direction of one principal surface) of the force F acting on the strain body 10, the output E ₁ of the first bridge circuit, and the output E ₃ of the third bridge circuit (=E ₁ - E ₃ ) can be measured based on The Y-direction component F _Y (other main surface direction component) of the force F acting on the strain body 10 is calculated by the difference between the output E ₂ of the second bridge circuit and the output E ₄ of the fourth bridge circuit (=E ₂ - E ₄ ). The Z-direction component F _Z (perpendicular component) of the force F acting on the strain body 10 is the sum of the outputs E ₁ to E ₄ of the first to fourth bridge circuits (=E ₁ +E ₂ +E ₃ +E ₄ ). can be measured based on Therefore, the measurement accuracy of the X-direction component, Y-direction component, and Z-direction component of the force F acting on the strain body 10 via the protrusion 11 is improved, and the force on the force sensor array including the plurality of force sensors 1 is improved. The measurement accuracy of the mode of action is improved.

(Other embodiments of the present invention)
In the embodiment, all the conductive members 20 are formed on the first main surface 101 of the strain-generating body 10, but in another embodiment, some of the conductive members 20 are formed on the first main surface 101. However, the remaining conductive member 20 may be formed on the second main surface 102. In this case, care must be taken because the positive and negative signs may differ depending on the first principal surface 101 and the second principal surface 102 depending on the position of the conductive member and the form of the load. A through hole may be provided in the strain body 10 in order to arrange a conductor member for configuring the strain detection circuit, or a conductor member having a via structure may be embedded in the strain body 10.

In the embodiment described above, the strain body 10 has a substantially circular plate shape, but in other embodiments, the strain body 10 may have a substantially elliptical plate shape, a substantially triangular plate shape, a substantially rectangular plate shape, or a substantially parallelogram plate shape. It may have various shapes, such as a substantially trapezoidal plate shape, a substantially regular polygonal plate shape (square, regular dodecagonal plate shape, regular icosagonal plate shape, etc.). The strain body 10 may have a shape that passes through the pole O and has rotational symmetry about an axis (for example, the Z axis) perpendicular to the first principal surface 101, or a shape that does not have rotational symmetry if the amount of strain is equal. Alternatively, the pole point O of the strain-generating body 10 may be shifted from the center point of the strain-generating body 10.

In the embodiment described above, the number of designated longitude ranges in which one group of conductive members constituting one bridge circuit is arranged on the first principal surface 101 of the strain-generating body 10 is "4"; The number may be 2 or 3 or a plurality of 5 or more.

In the embodiment described above, one conductive member group constituting one bridge circuit is disposed in each of a plurality of designated longitude ranges on the first principal surface 101 of the flexure element 10. One group of conductive members constituting one bridge circuit may be arranged only in a part of the specified longitude range.

In the embodiment described above, a bridge circuit using a 4-active gauge method was configured as one bridge circuit by the conductive members 20 arranged in a specified longitude range on the first principal surface 101 of the flexure element 10. One or two conductive members within a specified longitude range to configure a gauge method (2-wire or 3-wire) bridge circuit or 2 active gauge method (2-wire or 3-wire) bridge circuit. 20 may be arranged.

As shown in FIG. 12, each force sensor 1 may be fixed by the resin member 3 so that the entire force sensor 1 including the protrusion 11 is embedded in the resin member 3. In this case, as shown in FIG. 7, a protrusion 31 may be formed above the protrusion 11 to locally protrude or protrude the upper end surface of the resin member 3.

One or more conductive members 20 may be arranged in at least one designated latitude range out of a plurality of designated latitude ranges so as to extend in a substantially circular or circular arc shape separated at one point. . For example, as shown in FIG. 13, in each of the specified latitude ranges R ₊ and R _- of the first principal surface 101 of the flexure element 10, a substantially annular shape is divided at one point surrounding the reference point O. The conductive members 21 to 22 extending from the inside are arranged in order from the inside. Together with the conductive members 21 and 22, a bridge circuit of the two active gauge method is constructed.

The thickness, width, and length of each of the conductive members 21 to 22, as well as electrical characteristics such as electrical conductivity, are appropriately designed from the viewpoint of constructing a bridge circuit (strain detection circuit). The thickness, width, length, and material (which determines electrical conductivity) of the conductive wire member 2 are appropriately designed from the viewpoint of configuring the bridge circuit, similarly to each of the conductive members 21 to 22. ing.

When a force F acts on the strain body 10, a vertical force acts on the strain body 10 at each of a pair of locations on opposite sides of the pole O in each of the designated latitude ranges R ₊ and R _- . The polarity of the strain produced in both cases is the same (see FIG. 14A). On the other hand, in this case, the polarity of the strain that occurs when a force in the principal surface direction is applied to the strain body 10 at each of the pair of locations is reversed (see FIGS. 14B and 14C).

Therefore, at each pair of locations of the annular conductive members 21 to 22 that are separated at one location, the electrical resistance value changes depending on the amount of strain that occurs when a vertical force is applied to the flexure element 10. The changes are superimposed, and on the other hand, the changes in the electrical resistance value depending on the amount of strain that occur when a force in the main surface direction (X direction and Y direction) is applied can be canceled out. Therefore, based on the amount of change in the electrical resistance value between the respective end points of the conductive members 21 and 22, the main surface direction component of the force acting on the strain body 10 is removed, and the perpendicular direction component (Z direction) of the force is removed. components) can be measured with high precision. Further, two approximately annular conductive members 20 having the same resistance value are installed in each of the specified latitude ranges R ₊ and R _- , and a four-active gauge method can be used to perform measurement with higher accuracy.

A force sensor array is created by arranging a large number of diaphragm strain force sensor elements two-dimensionally, which have been made smaller by circumferential arrangement using lateral sensitivity, and forming them into a thin plate by embedding them in rubber, resin, etc. (resin member). By utilizing this, a flexible sheet-like sensor that can measure in-plane pressure distribution (surface pressure distribution) can be constructed. In general, it is preferable that the flexure element elements be arranged vertically and horizontally at regular intervals as shown in FIG. 1, with an appropriate width between the elements so as to enable flexible sheet-like bending. Numerical values such as the size of the flexure element, the arrangement interval of the elements, the inter-element width, and the overall size (number of elements) are determined depending on the use and specifications.

Also, depending on the application, instead of arranging the flexural elements at regular intervals in the vertical and horizontal directions, individual flexural elements may be installed at specific (arbitrary) positions (parts) within the sheet for distribution measurement. You can also use it.

The sheet state is formed by embedding arrayed flexure element elements and wiring in a resin member (a member made of engineering plastic such as rubber or resin). The material used for embedding, such as resin, is determined depending on the application from the viewpoint of strength, flexibility, heat resistance, etc., and may be made of not only a single material but also multiple materials.

The sheet shape, in terms of size (width) and thickness, basically has dimensions that allow it to be embedded in a state that covers all of the flexure element and electrode wiring (conductor wire member), and also has dimensions that allow it to be embedded in a state where it covers all of the flexure element and electrode wiring (conductor wire member). Quantity transferability, flexibility, buffering performance with the surrounding environment (elasticity, strength, protection of the flexure element), installation method and position of power input/signal output terminals, method of fixing them to the surroundings, and their locations, etc. It can be decided taking into account.

Basically, the strain element is embedded in the resin member, but a portion thereof, for example, the tip of the protruding portion, may be exposed outside the resin member. Furthermore, the flexural elements may not be embedded in a resin member, but may be joined to each other by welding or adhesive to form a sheet, or may be joined to other plate materials, etc. by welding or adhesive to form a sheet, and the outer peripheral fixed part or A part of it may be integrally continuous with other elements and form a sheet.

Electrode wiring (conductor wire members) for supplying power to each diaphragm type strain element and extracting signals from it can be connected individually or wired in a matrix and switched sequentially to input and output signals individually. It is possible to use existing wiring techniques that can also acquire position information, such as how to do this. In the case of a bridge, voltage is applied from the input side and a voltage signal is extracted from the output side. For example, when using the four-terminal method, a current is applied from the input side and a voltage signal is taken out from the output side. In addition, existing resistance change type signal detection methods can be used. Align the joint of the electrode wiring (conducting wire member) so that it overlaps the electrode formed on the sensor film (conductive member) forming surface of the diaphragm type strain element, and make sure contact with a pin probe or the like or by soldering. Attempt to join the electrode wiring (conducting wire member) by welding or the like. Signals obtained through the wiring are sequentially sent to measuring devices by switching devices such as relays, and are processed, recognized, recorded, and accumulated as data.

A pressure distribution sensor sheet can be formed by embedding an arrangement of diaphragm type strain body elements to which electrode wiring (conducting wire members) are bonded in a resin member. In addition, the flexure element elements arranged with the electrode parts exposed are embedded in a resin member in the form of a sheet, and the electrode wiring (conductor member) pattern formed on another resin sheet is connected to the exposed electrode part of the flexure element sheet. A pressure distribution sensor sheet consisting of the strain element and the wiring can be formed by overlapping the joint parts of the wiring and integrating them by adhesion or further embedding with a resin or the like.

Depending on the application and specifications, the protruding part that receives mechanical quantities such as force may have its lever tip protruding from the surface of the sheet made of resin material, so that input from the outside can be transmitted more smoothly and better. Alternatively, the resin member may be inflated and protruded from the sheet surface above the sensing portion.

In order to allow the diaphragm to sink well into the side where there is no sensing part, the area in contact with the diaphragm or the lower part may be made hollow with an area equivalent to that of the diaphragm, or rather than making that area hollow. Alternatively, it may be filled with a material that is more flexible than the resin member used to fill the surrounding area.

Such a flexible sheet-like sensor that can measure the in-plane pressure distribution (surface pressure distribution) made of the force sensor array according to the present invention can be used to A device for measuring force (pressure) distribution on the seat of a chair, on a bed when lying down, etc., a security device or a wandering detection device installed on the ground at entrances and windows, etc. , devices for measuring the distribution of 1-axis or 3-axis ground reaction forces or loads in the soles of shoes or inside shoes, devices for detecting the distribution of forces acting on things worn by the human body such as clothing, and tactile sensor devices for robots, etc. It can be expected to be applied to measuring various force distributions. Furthermore, since the line width of the conductive member can be made thinner to the limit possible with photolithography, it is also possible to create a diaphragm with a diameter on the order of microns, which can be used as an element to create an ultra-high resolution force distribution sensor. can be constructed.

DESCRIPTION OF SYMBOLS 1. Force sensor, 2. Conductive wire member, 3. Resin member, 10. Strainable body, 11. Protrusion, 12. Supporting portion, 20, 211-218, 221-228. Conductive member, 101. Strainable body. 102...Second principal surface of strain body, O...Pole, R ₊ ...Positive strain specified latitude range, R _-... Negative strain specified latitude range.

Claims (5)

A force sensor array comprising a plurality of force sensors, a plurality of conducting wire members, and a resin member that fixes the plurality of force sensors and the plurality of conducting wire members in a specified arrangement manner,
Each of the plurality of force sensors is
A flat plate-shaped strain body,
a protrusion that transmits force to the strain body;
a support part that supports the strain body continuously or discretely over the entire circumference;
an electrically conductive member having an isotropic gauge factor in the direction of the principal surface, the conductive member being disposed on at least one of the pair of principal surfaces of the strain-generating body;
When a force having a component perpendicular to the main surface acts on the flexure element, a first strain amount in the meridian direction of the flexure element and a second strain in the latitude direction of the flexure element with reference to the pole point. The conductive member is arranged on at least one main surface of the strain-generating body so as to extend in an arc shape in the latitude direction in a designated latitude range where the sum of the magnitudes of the two strain amounts is equal to or greater than a reference value,
The conductive wire member constitutes a strain detection circuit together with the conductive member,
The force sensor array is characterized in that the conductive member is a resistor whose electrical resistance value changes depending on the amount of strain of the strain-generating body . The force sensor array according to claim 1,
In each of a plurality of different specified longitude ranges of the strain-generating body of each of the plurality of force sensors, each of the plurality of groups of conductive members constituting each of the plurality of strain detection circuits is arranged in an arc shape in the latitude direction. A force sensor array, characterized in that the force sensor array is arranged on the main surface of the strain body so as to extend. The force sensor array according to claim 1,
In the specified latitude range of the strain body of each of the plurality of force sensors, the conductive member is arranged on the main surface of the strain body so as to extend in an annular shape surrounding the polar point separated at one point. A force sensor array characterized by: The force sensor array according to any one of claims 1 to 3,
The shape of the strain body has rotational symmetry with respect to an axis parallel to a perpendicular line of the main surface passing through the pole point or mirror symmetry with respect to a plane perpendicular to the main surface passing through the pole point,
The continuous or discrete support mode by the support portion at the periphery of the strain-generating body has rotational symmetry with respect to the axis or mirror symmetry with respect to the plane,
The force sensor array is characterized in that the conductive member is arranged on the main surface of the strain-generating body so as to have rotational symmetry with respect to the axis or mirror symmetry with respect to the plane. . The force sensor array according to any one of claims 1 to 4,
A force sensor array characterized in that the conductive member is composed of a Cr-based thin film.

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