WO2022168469A1 - Load sensor - Google Patents

Abstract

[Problem] To provide a load sensor that can be adaptable to a reduction in size while ensuring measurement accuracy. [Solution] This load sensor comprises: a strain generating body provided with a first strain measuring body and a second strain measuring body on a first plate surface; a holding body which mounts and holds the strain generating body; and a pressing body which presses a second plate surface of the strain generating body, wherein, when an in-plane virtual line of the first plate surface passing through the first strain measuring body and the second strain measuring body is defined as a first virtual line, the first strain measuring body and the second strain measuring body are positioned so as to sandwich a second virtual line which is orthogonal to the first virtual line and passes through a first center, and when the pressing body presses the strain generating body through contact that includes the center of the second plate surface, the holding body holds the strain generating body such that the first virtual line curves more than the second virtual line.

Description

load sensor

The present invention relates to load sensors.

Patent Literature 1 discloses a mounting portion provided with a mounting through-hole penetrating along a first direction, a deformation portion set on one side of the mounting portion, and a deformation portion set on one side of the deformation portion. a plate-like elastically deformable member capable of elastically deforming the deformable portion when a load in the first direction is applied to the receiving portion; and one side of the deformable portion facing the first direction. Alternatively, at least one of a strain detecting means disposed on the other side and outputting strain information corresponding to the deformation of the deformation portion, and one side or the other side of the mounting portion facing the first direction, and an annular mounting member fixed around the mounting through hole, the annular mounting member having an annular outer peripheral portion having a larger diameter than the mounting through hole, the annular outer peripheral portion A fixing portion fixed to the elastic deformation member is provided along the annular outer peripheral portion excluding the deformation portion side edge portion closest to the deformation portion of the portion, and the deformation portion side edge portion is attached to the mounting portion. A load sensor is disclosed that is arranged to extend along a third direction orthogonal to a second direction from a portion toward the receiving portion.

JP 2017-146135 A

Load sensors are used not only for vehicle seat occupancy detection purposes as described in Patent Document 1, but also for a variety of other purposes. Sometimes. Reducing the footprint is an ongoing issue for vehicle seat seating detection purposes as well. That is, the load sensor is required to be miniaturized while ensuring measurement accuracy.

An object of the present invention is to provide a load sensor that can be miniaturized while ensuring measurement accuracy.

In one aspect of the present invention for solving the above problems, a plate-shaped strain-generating body having a first strain-measuring body and a second strain-measuring body provided on a first plate surface which is one plate surface; A holding body that holds the strain body on the outer peripheral side of the first plate surface, and a pressing that presses a second plate surface of the strain body, which is a plate surface opposite to the first plate surface. and a body, wherein when an in-plane virtual line of the first plate surface passing through the first strain measurement body and the second strain measurement body is defined as a first virtual line, the first The first strain measuring body and the The second strain measuring body is positioned such that when the pressing body contacts a region including the center of the second plate surface and presses the strain generating body, the first virtual line is positioned relative to the second virtual line. The load sensor is characterized in that the holder holds the strain-generating body so that the strain-generating body is also curved.

Since the strain-generating body is mounted and held by the holder on its outer peripheral side, when the pressing body presses the strain-generating body, the strain-generating body is less likely to flex on the outer peripheral side, and the strain-generating body near the center of the first plate surface is bent. Deflection occurs preferentially. Since the strain-generating body is held by the holder so that the first virtual line is more curved than the second virtual line, the first strain-measuring body and the second strain-measuring body placed on the first virtual line are , the deflection of the flexure is easier to detect than other parts of the flexure. Therefore, the first strain measuring body and the second strain measuring body can detect the pressing force of the pressing body with high sensitivity.

In the invention disclosed in Patent Document 1 (invention 1), the deformable portion 12 of the mounting portion 11 is fixed at the mounting through-holes 11a and the receiving portion through-holes 13a at both ends thereof. Therefore, the bending of the deformation portion 12 is distributed to both ends. Therefore, in the present invention, the pressing force can be detected by the strain measuring body with high sensitivity as compared with the first invention.

In the load sensor described above, the holding body is spaced apart from the first center and is in contact with the first plate surface in a plurality of regions along the first imaginary line, thereby mounting and holding the strain generating body. may By arranging in this way, the strain body has a particularly high degree of curvature of the first imaginary line.

In the above-described load sensor, the first strain measuring body and the second strain measuring body are composed of strain resistors, and the strain resistor and a connection portion of a pair of electrodes connected to the strain resistor are connected to the strain resistor. It may be positioned along one virtual line.

When the strain resistor receives elongation strain, the resistance value in the elongation direction increases. Therefore, when the strain resistors constituting the first strain measuring body and the second strain measuring body and the wiring connected to the strain resistors are arranged so that the current flowing through the strain resistors flows along the first virtual line, The detection sensitivity of the pressing force by the first strain measuring body and the second strain measuring body is particularly high.

In the above load sensor, the distance between the first strain measurement body and the second virtual line may be equal to the distance between the second strain measurement body and the second virtual line. In this case, the first strain measurement body and the second strain measurement body are positioned symmetrically with respect to the second imaginary line.

In the above load sensor, the first virtual line may pass through the first center. In this case, the first strain measurement body and the second strain measurement body are positioned point-symmetrically with respect to the first center.

As described above, when the first strain measurement body and the second strain measurement body have a line-symmetrical relationship or a point-symmetrical relationship, the first strain measurement body and the first strain measurement body A first half-bridge circuit comprising a first resistor connected in series, and a second half-bridge circuit comprising a second strain measuring element and a second resistor connected in series to the second strain measuring element. may be provided on the first plate surface.

If the first strain-measuring body and the second strain-measuring body are positioned at equal distances across the second imaginary line, using a full bridge circuit including these will reduce disturbance in deformation measurement of the strain-generating body. Insensitive.

In the load sensor including the full-bridge circuit described above, both the first resistor and the second resistor are strain resistors, and the first resistor and the second resistor sandwich the first center. may be arranged symmetrically.

When the first resistor and the second resistor are made of strain resistors, the resistors incorporated in the full bridge can be made of the same material, which is expected to improve the productivity of the load sensor. In this case, since it is preferable that the first resistor and the second resistor have the same response characteristic to the pressing by the pressing body, they are preferably arranged symmetrically with respect to the first center.

In the case where the first resistor and the second resistor are made of strain resistors, the arrangement interval between the first strain measurement member and the second strain measurement member on the first plate surface is equal to the first resistor It may be shorter than the arrangement interval between the body and the second resistor on the first plate surface. In this specification, the point at which the arrangement interval is measured is the center of measurement for a member having a measuring function (such as a strain resistor), and the center of gravity for a resistor not having a measuring function.

It is found that the response characteristics of the first resistor and the second resistor to the pressure by the pressing body are less sensitive than the response characteristics of the first strain measurement body and the second strain measurement body to the pressure by the pressing body. Since it is preferable from the viewpoint of securing, it is preferable to adjust the arrangement interval in this manner.

In the load sensor including the full bridge circuit, the first resistor and the second resistor may be arranged along the second virtual line. By arranging the first resistor and the second resistor along the second imaginary line, the response characteristics of the first resistor and the second resistor to the pressing by the pressing body can be especially weakened.

In the above-described load sensor, the strain body preferentially deforms to bend the first virtual line when the pressing body presses the strain body so as to include the center of the second plate surface. It may have a region that is likely to be elastically deformed so as to occur in the strain body.

By preferentially generating the deformation that bends the first virtual line in the strain-generating body, it is possible to increase the detection sensitivity of the pressing force by the first strain-measuring body and the second strain-measuring body. Specifically, providing a notch in the strain body so as to overlap the second imaginary line when viewed from the pressing direction is exemplified.

In the above-described load sensor, the pressing body includes a pressing contact portion having a contact end in contact with the second plate surface, and an end of the pressing contact portion on the opposite side of the contact end to the second plate surface. and a pressing shaft portion extending along a linear direction. a holding shaft portion extending along the normal direction of the first plate surface from the side opposite to the position side, and the accommodating portion is arranged inside the hollow portion to hold the first strain-generating body. It may have a holding contact portion in contact with the plate surface, and a retaining portion for maintaining a state in which the strain generating body is held between the pressing contact portion and the holding contact portion.

Since the pressing shaft portion and the holding shaft portion are arranged substantially along the direction of the pressing shaft (pressing direction), the overall shape of the load sensor can be rod-shaped (cylindrical). For this reason, compared with the load sensor according to the invention 1, for example, it is possible to reduce the projected area (footprint) in the pressing direction.

In the load sensor having the above-described shape characteristics, the retaining portion is provided inside the hollow portion, and the pressing body is a flange portion protruding from a position closer to the pressing shaft portion than the contact end. and the flange portion may be engaged with the retaining portion. Specifically, for example, the retainer can be configured with an E-ring, and the pressing body and the holding body can be assembled with a simple structure.

According to the present invention, a load sensor that can be made compact while ensuring measurement accuracy is provided.

It is a figure showing a load sensor concerning one embodiment of the present invention. 1 is a diagram showing constituent elements of a load sensor according to an embodiment of the invention; FIG. 4 is a cross-sectional view of the load sensor cut along the XZ plane; FIG. 3 is a cross-sectional view of the load sensor taken along the YZ plane; FIG. FIG. 5 is a diagram showing a comparison between a deformed state (a) of a strain-generating body and a deformed state (b) of a strain-generating body according to the prior art; It is a figure which shows a strain-generating body. It is a bottom view of a strain-generating body. It is the front view (a) and side view (b) of a strain-generating body. FIG. 4 is a diagram showing deformation of a strain body when pressed by a pressing body; 4 is a plan view of a holding body; FIG. FIG. 3 is a cross-sectional view of the holding body cut along the XZ plane; FIG. 2 is a cross-sectional view of the holder cut along the YZ plane; FIG. 3 is a view showing a plan view of a holding body in which the shape of a strain generating body is superimposed. FIG. 3 is a view showing the shape of a strain generating body and the shape of a measuring section superimposed on a plan view of a holding body;

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same members are denoted by the same reference numerals, and the description of members that have already been described will be omitted as appropriate.

FIG. 1 is a diagram showing a load sensor according to one embodiment of the present invention. FIG. 2 is a diagram showing components of a load sensor according to one embodiment of the present invention. FIG. 3 is a cross-sectional view of the load sensor taken along the XZ plane. FIG. 4 is a cross-sectional view of the load sensor taken along the YZ plane. FIG. 5 is a diagram showing a comparison between the deformed state (a) of the strain-generating body and the deformed state (b) of the strain-generating body according to the prior art. FIG. 6 is a diagram showing a strain-generating body. FIG. 7 is a bottom view of the strain generating body. At the bottom right of FIG. 7, the part surrounded by the broken line circle in the central figure is enlarged and displayed. FIG. 8 is a front view (a) and a side view (b) of a strain body.

As shown in FIGS. 1 to 4, the load sensor 100 includes a plate-shaped strain body 10 having a plate surface along the XY plane, and one side of the strain body 10 (Z1-Z2 direction Z1 side). A holding body 20 for mounting and holding the strain body 10 on the outer peripheral side of the first plate surface 101, which is a plate surface, and the opposite side of the strain body 10 to the first plate surface 101 (Z1-Z2 direction Z2 side) and a pressing body 30 that presses the second plate surface 102 which is the plate surface of the plate. For example, when the load sensor 100 is used for the purpose of detecting seating of a vehicle seat, the holding body 20 is attached to the vehicle body side and the pressing body 30 is attached to the seat side.

As shown in FIGS. 6 to 8, the strain-generating body 10 has an outer shape obtained by cutting off both ends of a circle in a certain direction (the Y1-Y2 direction in FIG. 7) along parallel straight lines in a plan view. ing. The strain body 10 is preferably made of a material that can be elastically deformed appropriately while maintaining breaking strength. An insulating film is formed by printing on the first plate surface 101 of the strain generating body 10 to be described later, and a measuring circuit is formed on the insulating film.

As shown in FIGS. 3 and 4, the pressing body 30 has a pressing contact portion 31 having a contact end P in contact with the second plate surface 102 and a side (Z1-Z2 and a pressing shaft portion 32 extending along the normal direction (Z1-Z2 direction) of the second plate surface 102 from the end on the direction Z2 side). When the pressing body 30 presses the second plate surface 102 in its axial direction (Z1-Z2 direction), the contact end P of the pressing contact portion 31 includes the center (second center 102C) of the second plate surface 102. touch the area. In this embodiment, the pressing body 30 is a rotationally symmetrical body about an imaginary straight line along the Z1-Z2 direction.

The holding body 20 has an accommodating portion 21 having a hollow portion CP that accommodates the strain body 10 and the pressing contact portion 31, and the side of the accommodating portion 21 proximal to the pressing body 30 (Z1-Z2 direction Z2 side) is opposite. and a holding shaft portion 22 extending along the normal direction (Z1-Z2 direction) of the first plate surface 101 from the side (Z1-Z2 direction Z1 side). Note that the holding shaft portion 22 may have a structure having a through-hole penetrating from the extending direction tip portion (Z1-Z2 direction Z1 side) to the hollow portion CP. With such a structure, when the strain-generating body 10 is accommodated in the hollow portion CP, it is possible to route electrical wiring between the strain-generating body 10 and the outside through the through-holes. In this embodiment, the basic shape of the holder 20 is a rotationally symmetrical body having a rotation axis along the Z1-Z2 direction.

The accommodating portion 21 is in a state in which the strain body 10 is held between the holding contact portion 211 in contact with the first plate surface 101 of the strain body 10 inside the hollow portion CP, and the pressing contact portion 31 and the holding contact portion 211. and a retaining portion 212 for maintaining the

The pressing body 30 has a flange portion 311 protruding from a position closer to the pressing shaft portion 32 than the contact end P (Z1-Z2 direction Z2 side). The retaining portion 212 is provided inside the hollow portion CP, and the pressing body 30 is locked to the retaining portion 212 at the flange portion 311 . Specifically, for example, the retaining portion 212 can be composed of an E ring. In FIGS. 3 and 4, the E ring is fixed by engaging with a groove 21R provided on the inner surface of the hollow portion CP It is In this case, it is possible to assemble the pressing body 30 and the holding body 20 with a simple structure.

Here, in the load sensor shown in Invention 1, the member corresponding to the pressing shaft portion 32 of the pressing body 30 and the member corresponding to the holding shaft portion 22 of the holding body 20 do not overlap when viewed from the pressing direction. placed. Therefore, it is difficult to reduce the footprint of the load sensor.

On the other hand, in the load sensor 100, the pressing shaft portion 32 of the pressing body 30 and the holding shaft portion 22 of the holding body 20 are arranged so as to overlap when viewed from the pressing direction (Z1-Z2 direction). Therefore, it is possible to reduce the projected area (footprint) of the load sensor 100 in the pressing direction (Z1-Z2 direction). Further, since the pressing shaft portion 32 of the pressing body 30 and the holding shaft portion 22 of the holding body 20 are on the same axis, the strain body 10 can be pressed efficiently without dispersing the force.

As shown in FIG. 5A, since the holding contact portion 211 of the holder 20 holds the strain body 10 on the outer peripheral side of the first plate surface 101, the pressing body 30 is strain-generating. When the body 10 is pushed, elongation deformation occurs near the center of the first plate surface 101 of the strain body 10 . Strain is generated on the outer peripheral side of the first plate surface 101 of the strain body 10 by contacting the holding contact portion 211 , but since the strain body 10 is not fixed to the holding contact portion 211 , the strain is generated. No stretching deformation occurs on the outer peripheral side of the second plate surface 102 of the body 10 . Therefore, in the load sensor 100, it is sufficient to form a measurement circuit so that the vicinity of the center of the first plate surface 101 of the strain-generating body 10 can be appropriately measured. It becomes possible. This contributes to miniaturization of the load sensor 100 .

On the other hand, when the strain body 10X is fixed to the holder 20X at its outer periphery (FIG. 5(b)) as in the load sensor shown in Invention 1, the strain body 10X Elongation deformation occurs not only at the central portion of the first plate surface 101X but also at the outer peripheral portion of the second plate surface 102X. In invention 1, a full bridge circuit is formed to measure these extensional deformations. Therefore, the measurement circuit tends to be large, and it is difficult to reduce the size of the load sensor as a whole.

The holding contact portion 211 of the holding body 20 is provided mainly along the X1-X2 direction, as will be described later (see FIG. 10). In other words, the strain body 10 is supported mainly at both ends in the X1-X2 direction.

The measuring circuit provided in the strain generating body 10 will be described below.
As shown in FIG. 6 and the like, the first plate surface 101 of the strain body 10 is provided with a first strain measuring body 41 and a second strain measuring body 42 capable of strain measurement. The specific configurations of the first strain measurement body 41 and the second strain measurement body 42 are not particularly limited, except that they include a strain measurement section that can measure the elongation deformation of the first plate surface 101 . Non-limiting examples of these constituent materials include strain resistors. The strain resistor is a material whose resistance value changes by deforming following the deformation of the base material (strain generating body 10) on which the strain resistor is provided. For example, when the strain generating body 10 is elongated and deformed, the length of the strain resistor provided on the first plate surface 101 is extended, thereby increasing the resistance value.

More specifically, when the in-plane virtual line of the first plate surface 101 passing through the first strain measurement body 41 and the second strain measurement body 42 is defined as a first virtual line L1, the first strain measurement body 41 and the second strain measurement body 42 The electrode pattern connected to the strain measurement body 42 is routed so as to be orthogonal to the first virtual line L1, and the first strain measurement body 41 and the second strain measurement body 42 are arranged in the direction along the first virtual line L1. connected at both ends. Therefore, when the strain body 10 is stretched and deformed in the direction along the first imaginary line L1, the strain resistor is stretched and deformed, and the distance between the electrode patterns increases, thereby increasing the resistance value. Conversely, when the strain-generating body 10 elongates and deforms in the direction along the second virtual line L2, the strain resistor elongates and deforms, but the distance between the electrode patterns does not change, so there is no large change in the resistance value. In other words, it is less likely to be affected by anything other than elongation deformation in the direction along the first imaginary line L1.

Although the in-plane virtual line of the first plate surface 101 passing through the first strain measurement body 41 and the second strain measurement body 42 is referred to as the first virtual line L1, the first strain measurement body 41 and the second strain measurement body A supplementary explanation of what it means to pass through 42 will be given.

As shown in FIG. 7, a first measurement center 41C, which is the measurement center position on the first plate surface 101 of the first strain measurement body 41, and a measurement center position on the first plate surface 101 of the second strain measurement body 42 A second measurement center 42C is set. It can be said that the first measurement center 41C and the second measurement center 42C are points that serve as references when the strain measurement unit described above performs measurement. In many cases, the first measurement center 41C and the second measurement center 42C are the center points (center of gravity positions) of the strain measurement section, and the center points (center of gravity positions) of the first strain measurement body 41 and the second strain measurement body 42. There are many. Thus, in this specification, passing through the first strain measurement body 41 and the second strain measurement body 42 means passing through the first measurement center 41C and the second measurement center 42C.

As shown in FIG. 7, the first measurement center 41C and the second measurement center 42C are other in-plane imaginary lines of the first plate surface 101 orthogonal to the first imaginary line L1. They are positioned so as to sandwich a second imaginary line L2 passing through the first center 101C. The in-plane virtual line is curved according to the deflection when the plane is deflected.

The measurement center of the strain measuring body (first strain measuring body 41, second strain measuring body 42) is the normal direction (Z1-Z2 direction) corresponds to the center of gravity of the area located between the electrodes connected to the strain resistor. For example, when the strain measuring body has a structure in which a strain measuring portion provided on a semiconductor chip and its control IC are molded, the normal direction (Z1-Z2 direction) of the first plate surface 101 The center of gravity of the strain measuring unit when viewed corresponds to the measurement center of the strain measuring body.

When the pressing body 30 contacts a region including the center (second center 102C) of the second plate surface 102 and presses the strain body 10, as shown in FIG. The holding body 20 holds the strain body 10 so as to be curved more than the imaginary line L2. The degree of curvature of the in-plane virtual line of the first plate surface 101 is determined by how much the in-plane virtual line stretches, how much the curvature of the in-plane virtual line changes, and It is possible to quantitatively evaluate and make relative comparisons by, for example, how far the end of the curved portion of the in-plane virtual line is separated in the Z1-Z2 direction.

As described above, since the holder 20 supports the strain body 10 on the outer peripheral side of the first plate surface 101 , the deformation of the strain body 10 concentrates on the central portion of the first plate surface 101 . Therefore, by arranging the first strain measurement body 41 and the second strain measurement body 42 so that the first measurement center 41C and the second measurement center 42C sandwich the second imaginary line L2, efficient strain measurement can be performed in a narrow space. Deformation of the strain-generating body 10 can be measured.

Since the strain generating body 10 is held by the holding body 20 so that the first virtual line L1 is more curved than the second virtual line L2, the first strain measuring body 41 arranged on the first virtual line L1 and the second strain measurement body 42 are easier to detect the deflection of the strain body 10 than other parts of the strain body 10 . Therefore, the first strain measuring body 41 and the second strain measuring body 42 can detect the pressing force of the pressing body 30 with high sensitivity.

Such anisotropic curvature of the first plate surface 101 is derived from the structure of the holding contact portion 211 of the holder 20, as described below.

Specifically, the holding body 20 supports the strain generating body 10 at a location where the contact area between the holding contact portion 211 and the first plate surface 101 is spaced apart from the first center 101C, and the contact area of the contact area is held. The holding center, which is the center, is positioned along the first imaginary line L1.

FIG. 10 is a plan view of the holder. FIG. 11 is a cross-sectional view of the holder taken along the XZ plane. FIG. 12 is a cross-sectional view of the holder taken along the YZ plane. As shown in FIGS. 10 to 12, the surface of the holding contact portion 211 on the Z1-Z2 direction Z2 side is rotationally symmetrical with respect to the central axis of the outer shape of the holder 20 (along the Z1-Z2 direction). is not. The surface of the holding contact portion 211 on the Z1-Z2 direction Z2 side has a line-symmetrical shape with respect to the second imaginary line L2 along the Y1-Y2 direction, and the portion on the X1-X2 direction X1 side and the X1-X2 direction The portion on the X2 side has a portion wider than the portion on the Y1-Y2 direction Y1 side and the portion on the Y1-Y2 direction Y2 side.

FIG. 13 is a view showing the shape of the strain-generating body superimposed on the plan view of the holding body. A hatched portion is a contact area between the holding contact portion 211 and the strain body 10 . This contact area has two first contact areas CA1 and a second contact area CA2 aligned along the first imaginary line L1, that is, in the X1-X2 direction. The first contact area CA1 and the second contact area CA2 are arranged symmetrically across the second virtual line L2. That is, the first contact center CAC1, which is the center of gravity of the first contact area CA1 when viewed from the Z1-Z2 direction, and the second contact center CAC2, which is the center of gravity of the second contact area CA2 when viewed from the Z1-Z2 direction, are different. , along the first imaginary line L1.

In this way, the holder 20 holds the strain body 10 by contacting the first plate surface 101 in a plurality of areas along the first imaginary line L1 with the first center 101C interposed therebetween. Specifically, the holding contact portion 211 and the strain body 10 are in contact with each other in two regions (first contact region CA1 and second contact region CA2) separated from each other. It is held in a state where it is placed on the When the strain body 10 is pushed in the Z1-Z2 direction by the pressing body 30, the strain body 10 is bent so that the crease lines are along the Y1-Y2 direction, and the first plate of the strain body 10 is bent. A portion along the X1-X2 direction at the center of the surface 101 is preferentially elongated and deformed. By providing the strain measuring bodies (the first strain measuring body 41 and the second strain measuring body 42) in this portion, the pressing force can be efficiently measured.

More specifically, as shown in FIGS. 10 and 11, the surface of the holding contact portion 211 on the Z1-Z2 direction Z1 side is located on the Z1-Z2 direction Z1 side at the center of the holding contact portion 211 in the X1-X2 direction. It is separated by a stepped portion 213 formed in a recessed shape. When the strain body 10 is pushed in the Z1-Z2 direction Z1 side by the pressing body 30, the strain body 10 moves closer to the stepped portion 213 than the ridgeline 214 with the ridgeline 214 of the boundary between the holding contact portion 211 and the stepped portion 213 serving as a fulcrum. is pushed in the Z1-Z2 direction Z1 side, and the region closer to the holding contact portion 211 than the ridge line 214 deforms so as to rise in the Z1-Z2 direction Z2 side. As a result, the region R1 (see FIG. 10) sandwiched between the boundary ridgelines 214 in the X1-X2 direction is preferentially elongated and deformed. Therefore, as shown in FIG. 14, by providing the strain measuring bodies (the first strain measuring body 41 and the second strain measuring body 42) in this region R1, the pressing force can be efficiently measured.

In this embodiment, the first strain measuring body 41 and the second strain measuring body 42 are composed of the strain resistor SR, and the connection portions EC1 and EC2 of the pair of electrodes E1 and E2 connected to the strain resistor SR and the strain resistor SR is positioned along the first imaginary line L1 (see FIG. 7). That is, the pair of electrodes E1 and E2 connected to the strain resistor SR are arranged orthogonally to the first imaginary line L1, and the connecting portions EC1 and EC2 are the strain resistors in the direction along the first imaginary line L1. It is connected to both ends of SR. When the first plate surface 101 preferentially extends in the X1-X2 direction by the pressing body 30 pressing the strain generating body 10, the strain resistor SR provided on the first plate surface 101 extends in the X1-X2 direction. , the distance DE between the pair of electrodes E1 and E2 increases, and the resistance value between the pair of electrodes E1 and E2 changes. Therefore, if the wires connected to the strain resistors SR constituting the first strain measurement body 41 and the second strain measurement body 42 are arranged so that the current flowing through the strain resistors SR flows along the X1-X2 direction, The detection sensitivity of the pressing force by the first strain measurement body 41 and the second strain measurement body 42 is particularly high.

From the viewpoint of improving measurement accuracy, the distance D1 between the first measurement center 41C and the second virtual line L2 is preferably equal to the distance D2 between the second measurement center 42C and the second virtual line L2. In FIG. 7, the first imaginary line L1 passes through the first center 101C, which makes it possible to particularly improve the measurement accuracy.

As shown in FIG. 6 and the like, the first plate surface 101 is provided with a full bridge circuit 60 consisting of two half bridge circuits. That is, one of the two half-bridge circuits is the first half-bridge circuit 61 composed of the first strain measurement body 41 and the first resistor 51 connected in series with the first strain measurement body 41. One is a second half bridge circuit 62 comprising a second strain measuring body 42 and a second resistor 52 connected in series with the second strain measuring body 42 . In the load sensor 100, since the first strain measuring body 41 and the second strain measuring body 42 are arranged at equal distances across the second virtual line L2 (D1=D2), a full bridge circuit including these By using 60, deformation measurement of the strain generating body 10 that is less susceptible to disturbances is realized.

In this embodiment, both the first resistor 51 and the second resistor 52 are strain resistors, and the measurement center 51C of the first resistor 51 and the measurement center 52C of the second resistor 52 are aligned with the first center 101C. are arranged symmetrically across the Since the first resistor 51 and the second resistor 52 are made of strain resistors, the resistors incorporated in the full bridge circuit 60 can be made of the same material, which is expected to improve the productivity of the load sensor 100. . In this case, since it is preferable that the first resistor 51 and the second resistor 52 have the same response characteristic to the pressing by the pressing body 30, they are preferably arranged symmetrically with respect to the first center 101C as described above. .

Further, in the present embodiment, the arrangement interval DM between the first strain measurement body 41 and the second strain measurement body 42 on the first plate surface 101 is the first distance between the first resistor 51 and the second resistor 52 . It is shorter than the arrangement interval DL on the plate surface 101 (see FIG. 7). The response characteristics of the first resistor 51 and the second resistor 52 to pressing by the pressing body 30 are less sensitive than the response characteristics of the first strain measuring body 41 and the second strain measuring body 42 to pressing by the pressing body 30. is preferable from the viewpoint of securing the measurement accuracy of the pressing force, it is preferable to adjust the arrangement interval in this manner.

FIG. 14 is a diagram in which the shape of the strain-generating body and the shape of the measurement part are superimposed on the plan view of the holding body. As shown in FIG. 14, in this embodiment, the first contact center CAC1 and the second contact center CAC2 as well as the first measurement center 41C and the second measurement center 42C are all on the first imaginary line L1. Since the first contact center CAC1 and the second contact center CAC2 are on the first imaginary line L1, the first imaginary line L1 extends the most when the strain body 10 is pushed in the Z1-Z2 direction by the pressing body 30. transform. Therefore, the first strain measurement body 41 and the second strain measurement body 42 whose measurement centers (first measurement center 41C, second measurement center 42C) are located on the first virtual line L1 are arranged on the first virtual line L1. It expands and deforms greatly along the length of the surface, and efficient measurement of the pressing force can be realized more stably.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is meant to include all design changes and equivalents that fall within the technical scope of the present invention.

For example, the first resistor 51 and the second resistor 52 may be normal resistors instead of strain resistors. In this case, the resistance values of the first resistor 51 and the second resistor 52 do not change even if the strain generating body 10 is deformed. does not affect the measurement accuracy of

When the strain body 10 is pressed so that the pressing body 30 includes the center of the second plate surface 102, the strain body 10 is preferentially deformed to bend the first imaginary line L1. , it may have a region that is likely to be elastically deformed. Specifically, for example, a region extending in the Y1-Y2 direction through the second center 102C of the second plate surface 102 of the strain body 10 has a groove (notch), or this region is made of a material with a low Young's modulus. It may be replaced. In FIG. 8, grooves (notches) are indicated by phantom lines.

REFERENCE SIGNS LIST 10: strain-generating body 10X: strain-generating body 20 of a load sensor according to conventional technology: holding body 20X: holding body 21 of a load sensor according to conventional technology: housing portion 21R: groove 22 on the inner surface of the hollow portion: holding shaft portion 30 : Pressing body 31 : Pressing contact part 32 : Pressing shaft part 41 : First strain measuring body 41C : First measuring center 42 : Second strain measuring body 42C : Second measuring center 51 : First resistor 51C : First resistor Body measurement center 52: second resistor 52C: second resistor measurement center 60: full bridge circuit 61: first half bridge circuit 62: second half bridge circuit 100: load sensor 101: first plate surface 101C: First center 101X: First plate surface 102 according to conventional technology: Second plate surface 102C: Second center 102X: Second plate surface 211 according to conventional technology: Holding contact portion 212: Retaining portion 213: Stepped portion 214: Ridgeline 311 : Flange portion CA1 : First contact area CA2 : Second contact area CAC1 : First contact center CAC2 : Second contact center CP : Hollow portion D1 : Distance D2 : Distance DE : Distance DL between electrodes E1 and E2 : Layout interval DM : Layout interval E1 : Electrode E2 : Electrode L1 : First virtual line L2 : Second virtual line P : Contact edge R1 : Region SR : Strain resistor EC1 : Connection EC2 between electrode E1 and strain resistor SR : connection part between the electrode E2 and the strain resistor SR

Claims (12)

a plate-shaped strain-generating body having a first strain-measuring body and a second strain-measuring body provided on a first plate surface, which is one plate surface;
a holding body that supports and holds the strain generating body on the outer peripheral side of the first plate surface;
a pressing body that presses a second plate surface opposite to the first plate surface of the strain generating body;
A load sensor comprising
When the in-plane virtual line of the first plate surface passing through the first strain measurement body and the second strain measurement body is defined as a first virtual line,
The first strain so as to sandwich a second virtual line that is another in-plane virtual line of the first plate surface orthogonal to the first virtual line and that passes through a first center that is the center of the first plate surface. the measuring body and the second strain measuring body are positioned;
The holding body is configured such that when the pressing body contacts a region including the center of the second plate surface and presses the strain generating body, the first virtual line is curved more than the second virtual line. A load sensor that holds the strain-generating body. The holding body is spaced apart from the first center and is in contact with the first plate surface in a plurality of regions along the first imaginary line, thereby mounting and holding the strain generating body. Item 1. The load sensor according to item 1. The first strain measuring body and the second strain measuring body are composed of strain resistors,
3. The load sensor according to claim 1, wherein a connecting portion of a pair of electrodes connected to said strain resistor and said strain resistor are positioned along said first imaginary line. 4. The distance between the first strain measuring body and the second virtual line is equal to the distance between the second strain measuring body and the second virtual line according to any one of claims 1 to 3. load sensor. The load sensor according to any one of claims 1 to 4, wherein said first imaginary line passes through said first center. A first half-bridge circuit comprising the first strain-measuring body and a first resistor connected in series with the first strain-measuring body, and a second strain-measuring body connected in series with the second strain-measuring body. 6. The load sensor according to claim 4, wherein a full bridge circuit comprising a second half bridge circuit comprising a second resistor and a second resistor is provided on the first plate surface. 7. The method according to claim 6, wherein both said first resistor and said second resistor are strain resistors, and said first resistor and said second resistor are arranged symmetrically with respect to said first center. Load sensor as described. The arrangement interval of the first strain measurement body and the second strain measurement body on the first plate surface is larger than the arrangement interval of the first resistor and the second resistor on the first plate surface. 8. The load sensor of claim 7, short. The load sensor according to claim 7 or 8, wherein said first resistor and said second resistor are arranged along said second imaginary line. When the strain body is pressed so that the pressing body includes the center of the second plate surface, the strain body is preferentially deformed to bend the first imaginary line. 10. The load sensor according to any one of claims 1 to 9, wherein the load sensor has a region that is easily deformed elastically. The pressing body includes a pressing contact portion having a contact end in contact with the second plate surface, and an end portion of the pressing contact portion opposite to the contact end, extending along the normal direction of the second plate surface. and a pressing shaft portion present,
The holding body includes an accommodating portion having a hollow portion that accommodates the strain generating body and the pressing contact portion, and a normal line of the first plate surface from the opposite side of the accommodating portion to the side proximal to the pressing body in the accommodating portion. a holding shaft extending along a direction;
The accommodating portion has a holding contact portion in contact with the first plate surface of the strain-generating body inside the hollow portion, and a state in which the strain-generating body is sandwiched between the pressing contact portion and the holding contact portion. 10. The load sensor according to any one of claims 1 to 9, further comprising a retainer for retaining. The retaining portion is provided inside the hollow portion,
12. The load sensor according to claim 11, wherein the pressing body has a flange portion protruding from a position closer to the pressing shaft portion than the contact end, and the flange portion is locked by the retaining portion. .

Images