Detection device

Abstract

To provide a detection device that can more accurately detect shear force. [Solution] First, based on the change in capacitance between the lower electrode and the upper electrode, a pressing force detection value reflecting the pressing force applied in the z-axis direction and a shear force detection value reflecting the shear force applied in at least one of the x-axis and y-axis directions are calculated (steps S1-S2). Next, a pressing force conversion value obtained by converting the pressing force detection value to a predetermined unit and a shear force conversion value obtained by converting the shear force detection value to a predetermined unit are calculated (steps S3-S4). At this time, the shear force conversion value is converted according to the pressing force detection value or the pressing force conversion value. This makes it possible to output the shear force detection value more accurately.

Description

Technical Field

[0001] The present invention relates to a detection device for detecting an external force.

Background Art

[0002] Conventionally, a detection device for detecting an external force applied to a sheet-like sensor body has been known. A conventional detection device is described in, for example, Patent Document 1. The detection device of Patent Document 1 has a lower electrode and an upper electrode. In the detection device of Patent Document 1, a pressing force and a shearing force applied to the sensor body are detected based on a change in capacitance between the lower electrode and the upper electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the detection device of Patent Document 1, an elastic body is interposed between the lower electrode and the upper electrode. When a shearing force is applied to the surface of the sensor body, the elastic body is deformed, so that the position of the upper electrode with respect to the lower electrode is displaced in the direction of the shearing force. As a result, the capacitance between the lower electrode and the upper electrode changes. The detection device outputs a detection value of the shearing force based on this change in capacitance.

[0005] However, when a shearing force is applied, a pressing force is always applied. Since the ease of deformation of the elastic body in the shearing direction changes according to the strength of the pressing force, it has been difficult to accurately detect the shearing force only by the change in capacitance.

[0006] Therefore, an object of the present invention is to provide a detection device capable of more accurately detecting a shearing force.

Means for Solving the Problems

[0007] One aspect of the present invention is a detection device for detecting an external force, comprising a sheet-shaped sensor body and a detection unit electrically connected to the sensor body, wherein the sensor body has an elastic layer, a plurality of lower electrodes disposed on the lower surface of the elastic layer, and an upper electrode disposed on the upper surface of the elastic layer and spanning at least two adjacent lower electrodes in a top view, and the detection unit performs a detection value calculation process that calculates a pressing force detection value that reflects the pressing force applied in the z-axis direction perpendicular to the surface of the sensor body, and a shear force detection value that reflects the shear force applied in at least one of the x-axis and y-axis directions along the surface of the sensor body, based on the change in capacitance between the lower electrodes and the upper electrodes, and a correction process that corrects the shear force detection value according to the pressing force detection value.

[0008] It is desirable that the correction process be performed such that the shear force detection value increases as the pressing force detection value increases.

[0009] The detection unit preferably corrects the shear force detection value according to the calibration curve and changes the sensitivity coefficient, which is the slope of the calibration curve, according to the pressing force detection value.

[0010] Another aspect of the present invention is a detection device for detecting an external force, comprising a sheet-shaped sensor body and a detection unit electrically connected to the sensor body, wherein the sensor body has an elastic layer, a plurality of lower electrodes disposed on the lower surface of the elastic layer, and an upper electrode disposed on the upper surface of the elastic layer and spanning at least two adjacent lower electrodes in a top view, and the detection unit performs a detection value calculation process that calculates a pressing force detection value that reflects the pressing force applied in the z-axis direction perpendicular to the surface of the sensor body, and a shear force detection value that reflects the shear force applied in at least one of the x-axis and y-axis directions along the surface of the sensor body, based on the change in capacitance between the lower electrodes and the upper electrodes, and a unit conversion process that calculates a pressing force conversion value obtained by converting the pressing force detection value to a predetermined unit and a shear force conversion value obtained by converting the shear force detection value to the predetermined unit, wherein in the unit conversion process, the shear force conversion value is converted according to the pressing force detection value or the pressing force conversion value.

[0011] In the aforementioned unit conversion process, it is desirable to increase the shear force conversion value as the detected pressing force value or the converted pressing force value increases.

[0012] The detection unit preferably calculates the shear force conversion value from the shear force detection value according to the calibration curve, and changes the sensitivity coefficient, which is the slope of the calibration curve, according to the pressing force detection value or the pressing force conversion value.

[0013] It is desirable that the calibration curve be a linear function represented by F = P / a, where P is the detected shear force, F is the converted shear force, and a is the sensitivity coefficient.

[0014] It is desirable that the relationship between the sensitivity coefficient a and the pressure-converted value Fz be a linear function expressed as a = A × Fz + B, where Fz is the pressure-converted value, A is a negative coefficient, and B is a positive coefficient.

[0015] It is desirable that the relationship between the sensitivity coefficient a and the pressure-converted value Fz be an nth-degree function represented by a = f(Fz), where Fz is the pressure-converted value.

[0016] In the unit conversion process, it is desirable for the detection unit to convert the shear force detection value into the unit of Newton.

Advantages of the Invention

[0017] According to the present invention, the shear force can be detected more accurately.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram of the detection device. [Figure 2] It is a partial longitudinal sectional view of the sensor body. [Figure 3] It is a flowchart showing the flow of the detection process. [Figure 4] It is a partial longitudinal sectional view of the sensor body when a pressing force in the z-axis direction is applied to the upper surface of the cover layer. [Figure 5] It is a partial longitudinal sectional view of the sensor body when a shear force in the x-axis direction is applied to the upper surface of the cover layer. [Figure 6] It is a diagram showing an example of a calibration curve. [Figure 7] It is an example graph showing the correspondence between the pressing force conversion value and the sensitivity coefficient. [Figure 8] It is a flowchart showing the detailed procedure of the conversion process of the shear force. [Figure 9] It is a flowchart showing the flow of the detection process according to the modification example. [Figure 10] It is a diagram showing an example of a calibration curve. [Figure 11] It is an example graph showing the correspondence between the pressing force detection value and the sensitivity coefficient. [Figure 12] It is a flowchart showing the detailed procedure of the correction process of the shear force detection value.

Modes for Carrying Out the Invention

[0019] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the directions along the surface of the sensor body 1 will be referred to as the x-axis and y-axis directions. The x-axis and y-axis directions intersect each other (for example, are orthogonal). The direction perpendicular to the surface of the sensor body 1 will be referred to as the z-axis direction.

[0020] Furthermore, in the following explanation, the side with the support layer 10 (described later) will be referred to as "bottom" and the side with the cover layer 50 (described later) will be referred to as "top" along the z-axis, and the structure of each part will be described accordingly. However, the terms "top" and "bottom" in the following explanation are used for convenience in describing the structure and do not limit the orientation of the sensor body 1 when in use.

[0021] <1. Configuration of the detection device> Figure 1 is a schematic diagram of a detection device 100 according to one embodiment of the present invention. This detection device 100 is a device that detects external forces such as pressing force and shear force applied to the sensor body 1. The detection device 100 is used, for example, to verify what kind of forces are generated in the manufacturing process of industrial products, or in medical, nursing care, and sports settings. However, the detection device 100 may be used for purposes other than those mentioned above.

[0022] As shown in Figure 1, the detection device 100 comprises a sheet-shaped sensor body 1 and a detection unit 2. The sensor body 1 and the detection unit 2 are electrically connected by a flexible printed circuit board 3. The detection unit 2 has a detection circuit 4. The detection circuit 4 detects the external force acting on the sensor body 1 by measuring the change in capacitance between electrodes provided inside the sensor body 1.

[0023] Figure 2 is a partial longitudinal cross-sectional view of the sensor body 1. As shown in Figure 2, the sensor body 1 has a support layer 10, a lower electrode layer 20, an elastic layer 30, an upper electrode layer 40, and a cover layer 50. The support layer 10, lower electrode layer 20, elastic layer 30, upper electrode layer 40, and cover layer 50 are stacked in this order from bottom to top.

[0024] The support layer 10 is located at the bottom of the sensor body 1. The support layer 10 has higher rigidity than the elastic layer 30 and the cover layer 50. The material used for the support layer 10 is an insulator such as resin or glass. The support layer 10 may be composed of multiple layers.

[0025] The lower electrode layer 20 is formed on the upper surface of the support layer 10. A conductive metal is used as the material for the lower electrode layer 20. Specifically, metal oxides such as gold, silver, copper, aluminum, indium oxide, tin oxide, indium tin oxide (ITO), and tin antimonate, as well as platinum, palladium, and rhodium, are used as the material for the lower electrode layer 20. The surface resistance of the lower electrode layer 20 is, for example, several mΩ / □ to several hundred Ω / □.

[0026] The lower electrode layer 20 has a plurality of lower electrodes 21. The plurality of lower electrodes 21 are arranged in a matrix on the upper surface of the support layer 10 in the x-axis and y-axis directions. The size of the area where the plurality of lower electrodes 21 are arranged (pressure-sensitive area) is, for example, about 30 cm × 30 cm. However, the size of the pressure-sensitive area is not limited to the above example.

[0027] The elastic layer 30 is interposed between the lower electrode layer 20 and the upper electrode layer 40. The elastic layer 30 is provided over the entire surface between the upper surface of the support layer 10 on which the lower electrode layer 20 is formed and the lower surface of the cover layer 50 on which the upper electrode layer 40 is formed. Therefore, the multiple lower electrodes 21 are arranged on the lower surface of the elastic layer 30. The multiple upper electrodes 41 are arranged on the upper surface of the elastic layer 30. The elastic layer 30 becomes the dielectric of the parallel plate capacitor composed of the lower electrodes 21 and the upper electrodes 41.

[0028] The elastic layer 30 is made of a material that is an insulator and can be elastically deformed in response to external forces. Specifically, the elastic layer 30 can be a silicone-based, acrylic-based, urethane-based, or olefin-based gel sheet, or other foam sheets, rubber sheets, resin sheets, or nonwoven fabric sheets. The elastic layer 30 may also be a foam material containing a large number of fine bubbles. The thickness of the elastic layer 30 is, for example, 0.02 to 2 mm. Although the elastic layer 30 in this embodiment has been described as a single layer, the elastic layer 30 may be composed of multiple layers made of the same or different materials.

[0029] The upper electrode layer 40 is formed on the underside of the cover layer 50. The upper electrode layer 40 is made of a conductive metal. Specifically, metal oxides such as gold, silver, copper, aluminum, indium oxide, tin oxide, indium tin oxide (ITO), and tin antimonate, as well as platinum, palladium, and rhodium, are used as the material for the upper electrode layer 40. The surface resistance of the upper electrode layer 40 is, for example, several mΩ / □ to several hundred Ω / □.

[0030] The upper electrode layer 40 has a plurality of upper electrodes 41. The plurality of upper electrodes 41 are arranged on the lower surface of the cover layer 50. As shown in Figure 2, the lower electrodes 21 and the upper electrodes 41 face each other in the z-axis direction via the elastic layer 30. Some of the upper electrodes 41 are positioned to straddle at least two adjacent lower electrodes 21 in the x-axis direction when viewed from above. Other upper electrodes 41 are positioned to straddle at least two adjacent lower electrodes 21 in the y-axis direction when viewed from above.

[0031] In Figure 2, the two adjacent lower electrodes 21 in the x-axis direction are distinguished by their sign codes, 21a and 21b. In a top view, the upper electrode 41 in Figure 2 overlaps a portion of one lower electrode 21a and a portion of the other lower electrode 21b. As a result, a first capacitor 61 is formed between the upper electrode 41 and one lower electrode 21a, and a second capacitor 62 is formed between the upper electrode 41 and the other lower electrode 21b.

[0032] The cover layer 50 is the layer that receives the external force to be detected. The cover layer 50 is located at the top of the sensor body 1. The top surface of the cover layer 50 is the surface exposed to the outside of the sensor body 1. The material used for the cover layer 50 is an insulating resin. The cover layer 50 may be composed of multiple layers.

[0033] <2. About the detection process> Next, we will explain the process of detecting external forces by the detection device 100. Figure 3 is a flowchart showing the flow of the detection process.

[0034] In the following, the capacitance of the first capacitor 61 described above will be denoted as C1, and the capacitance of the second capacitor 62 described above will be denoted as C2. Furthermore, the capacitances C1 and C2 in the no-load state, when no external force is applied to the sensor body 1, will be denoted as C1o and C2o, respectively. In this embodiment, capacitances C1o and C2o are considered equivalent. However, it is not essential that capacitances C1o and C2o are equivalent; it is sufficient to know the change in capacitance.

[0035] Figure 4 is a partial longitudinal cross-sectional view of the sensor body 1 when a pressing force in the z-axis direction is applied to the upper surface of the cover layer 50. In Figure 4, the cover layer 50 and upper electrode 41 in the unloaded state are shown by dashed lines, and the cover layer 50 and upper electrode 41 in the state when a pressing force in the z-axis direction is applied are shown by solid lines.

[0036] As shown in Figure 4, when a pressing force in the z-axis direction is applied to the upper surface of the cover layer 50, the elastic layer 30 contracts in the z-axis direction. As a result, the upper electrode 41 at the position where the pressing force is applied is displaced downward. Therefore, as shown in Figure 4, the distance in the z-axis direction between that upper electrode 41 and the lower electrodes 21a and 21b below it decreases. Consequently, the capacitance C1 of the first capacitor 61 and the capacitance C2 of the second capacitor 62 both increase.

[0037] The increase in capacitance C1 and C2 increases with increasing pressure in the z-axis direction. Therefore, the magnitude of the pressure in the z-axis direction correlates with the detected pressure value Pz, which is expressed by the following formula (1). The detection unit 2 measures the capacitance C1 and C2 of the first capacitor 61 and the second capacitor 62, and calculates the detected pressure value Pz, which reflects the pressure in the z-axis direction, by substituting the obtained measured values ​​into formula (1) (step S1). Pz = (C1 + C2) / (C10 + C20) - 1 (1)

[0038] Figure 5 is a partial longitudinal cross-sectional view of the sensor body 1 when a shear force in the x-axis direction is applied to the upper surface of the cover layer 50. In Figure 5, the upper electrode 41 in the unloaded state is shown by a dashed line, and the upper electrode 41 with a shear force in the x-axis direction applied is shown by a solid line.

[0039] As shown in Figure 5, when a shear force is applied to the cover layer 50 from one lower electrode 21a to the other lower electrode 21b, the position of the upper electrode 41 moves in the x-axis direction toward the other lower electrode 21b. As a result, the capacitance C1 of the first capacitor 61 decreases, and the capacitance C2 of the second capacitor 62 increases. These changes in capacitance C1 and C2 become larger as the shear force increases.

[0040] When a shear force is applied in the y-axis direction, if the capacitances of adjacent capacitors in the y-axis direction are C1 and C2, their capacitances C1 and C2 will change in the same manner as described above.

[0041] Therefore, the magnitude of the shear force in the x-axis or y-axis direction correlates with the shear force detection value Pxy, which is expressed by the following formula (2). The detection unit 2 measures the capacitances C1 and C2 of the first capacitor 61 and the second capacitor 62, and calculates the shear force detection value Pxy that reflects the shear force in the x-axis or y-axis direction by substituting the obtained measured values ​​into formula (2) (step S2). Pxy = C2 / (C1 + C2) - 1 / 2 (2)

[0042] The processing in steps S1 and S2 is an example of the "detection value calculation process" in this embodiment. Note that the execution order of steps S1 and S2 may be reversed. Also, the detection unit 2 may execute steps S1 and S2 simultaneously.

[0043] Next, the detection unit 2 converts the pressure detection value Pz calculated in step S1 into a predetermined unit (step S3). In this embodiment, the detection unit 2 calculates a pressure conversion value Fz by converting the pressure detection value Pz into units of Newtons (N).

[0044] In step S3, the detection unit 2 converts the detected pressure value Pz calculated in step S1 into the converted pressure value Fz, according to a calibration curve that shows the correspondence between the detected pressure value Pz and the converted pressure value Fz. The calibration curve is, for example, a linear function represented by the following equation (3). In equation (3), az is a sensitivity coefficient that indicates the slope of the calibration curve. The sensitivity coefficient az in equation (3) is determined in advance by sensitivity measurement and is stored as a fixed value in the memory of the detection unit 2. The detection unit 2 substitutes the detected pressure value Pz calculated in step S1 into equation (3). This calculates the converted pressure value Fz, which is expressed in units of Newtons (N). Fz = Pz / az (3)

[0045] Next, the detection unit 2 converts the shear force detection value Pxy calculated in step S2 into a predetermined unit (step S4). In this embodiment, the detection unit 2 calculates a shear force conversion value Fxy by converting the shear force detection value Pxy into units of Newtons (N).

[0046] In step S4, the detection unit 2 converts the shear force detected value Pxy calculated in step S2 into a shear force converted value Fxy according to a calibration curve that shows the correspondence between the shear force detected value Pxy and the shear force converted value Fxy. The calibration curve is, for example, a linear function represented by the following equation (4). In equation (4), axy is a sensitivity coefficient that indicates the slope of the calibration curve. Figure 6 shows an example of the calibration curve of equation (4). Fxy = Pxy / axy (4)

[0047] The processing in steps S3 to S4 is an example of the "unit conversion processing" in this embodiment. The detection unit 2 outputs the pressing force conversion value Fz calculated in step S3 and the shear force conversion value Fxy calculated in step S4 to the outside.

[0048] Here, as shown in Figure 4, when a pressing force in the z-axis direction is applied to the sensor body 1, the elastic layer 30 is compressed in the z-axis direction. In this state, the elastic layer 30 becomes less prone to deformation in the x-axis and y-axis directions, so even when a shear force is applied, the position of the upper electrode 41 is less likely to move in the x-axis and y-axis directions. Therefore, even when the same shear force is applied, the shear force detection value Pxy calculated by equation (2) is smaller when the pressing force in the z-axis direction is larger than when the pressing force in the z-axis direction is smaller.

[0049] Therefore, in step S4, the detection unit 2 increases the shear force conversion value Fxy as the pressing force detection value Pz or pressing force conversion value Fz increases. Specifically, the detection unit 2 changes the sensitivity coefficient axy in the above-mentioned formula (4) according to the pressing force detection value Pz or pressing force conversion value Fz.

[0050] Figure 7 is an example of a graph showing the correspondence between the pressure-converted value Fz and the sensitivity coefficient axy. In the example in Figure 7, the correspondence between the pressure-converted value Fz and the sensitivity coefficient axy is represented by a linear function expressed by the following equation (5). In equation (5), A is a coefficient that indicates the slope of the graph. In equation (5), B is a coefficient that indicates the intercept of the graph. Coefficient A is a negative value, and coefficient B is a positive value. Coefficients A and B are determined in advance by sensitivity measurement and are stored as fixed values ​​in the memory of the detection unit 2. axy = A × Fz + B (5)

[0051] Figure 8 is a flowchart showing the detailed procedure of step S4. As shown in Figure 8, in step S4, the detection unit 2 first calculates the sensitivity coefficient axy based on the pressure conversion value Fz (step S41). Specifically, the sensitivity coefficient axy is calculated by substituting the pressure conversion value Fz calculated in step S3 into formula (5). As a result, the larger the pressure conversion value Fz, the smaller the sensitivity coefficient axy can be.

[0052] Next, the detection unit 2 calculates the shear force equivalent value Fxy using the sensitivity coefficient axy calculated in step S41 (step S42). Specifically, the detection unit 2 substitutes the shear force detection value Pxy calculated in step S2 and the sensitivity coefficient axy calculated in step S41 into formula (4). This calculates the shear force equivalent value Fxy, which is expressed in Newtons (N). The calculated shear force equivalent value Fxy increases as the compressive force equivalent value Fz increases.

[0053] As a result of diligent research, the inventors of the present application discovered that, even when applying the same strength of shear force, when a large pressing force is applied, the upper electrode 41 becomes less likely to move in the direction of the shear force relative to the lower electrode 21, and when a small pressing force is applied, the upper electrode 41 becomes more likely to move in the direction of the shear force relative to the lower electrode 21, resulting in variability in the detected shear force. To address this problem, by performing the processing in steps S41 to S42 described above, it became possible to accurately detect the shear force while taking into account the effect of the pressing force.

[0054] As described above, the detection device 100 of this embodiment calculates the shear force conversion value Fxy by taking into consideration that the more the elastic layer 30 is compressed in the z-axis direction, the less it is deformable in the x-axis and y-axis directions. This allows for a more accurate output of the shear force conversion value Fxy.

[0055] In the example shown in Figure 7, the sensitivity coefficient axy was calculated based on the pressure-converted value Fz. However, the horizontal axis in Figure 7 may be changed from the pressure-converted value Fz to the pressure-detected value Pz, and the sensitivity coefficient axy may be calculated based on the pressure-detected value Pz.

[0056] Furthermore, in the above embodiment, the detection unit 2 converted the detected pressing force value Pz and the detected shear force value Pxy to units of Newtons (N) in steps S3 to S4. However, the detection unit 2 may also convert the detected pressing force value Pz and the detected shear force value Pxy to units of pressure per unit area in steps S3 to S4. For example, the detection unit 2 may convert the detected pressing force value Pz and the detected shear force value Pxy to units of Pascals (Pa) or millimeters of mercury (mmHg) in steps S3 to S4.

[0057] Furthermore, in step S4 of this embodiment, the detection unit 2 uses a linear function represented by formula (4) to show the calibration curve that indicates the correspondence between the detected shear force value Pxy and the converted shear force value Fxy. However, the calibration curve that indicates the relationship between the detected shear force value Pxy and the converted shear force value Fxy may also be an nth-degree function (a function of the second degree or higher).

[0058] <3. Variant> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Below, various modifications will be described, focusing on the differences from the above embodiment.

[0059] <3-1. First variation> Figure 9 is a flowchart showing the flow of the detection process according to one modified example. In the above embodiment, when performing unit conversion of shear force, the shear force conversion value Fxy was adjusted by considering the pressing force in the z-axis direction. In contrast, the example in Figure 9 differs from the above embodiment in that no unit conversion is performed.

[0060] In the example shown in Figure 9, the detection unit 2 first calculates the pressing force detection value Pz (step S1) and the shear force detection value Pxy (step S2), similar to the embodiment described above. Subsequently, the detection unit 2 corrects the shear force detection value Pxy according to the pressing force detection value Pz (step S5). The process in step S5 is an example of the "correction process" in this embodiment.

[0061] In step S5, for example, the detection unit 2 corrects the shear force detection value Pxy according to a calibration curve that shows the correspondence between the shear force detection value Pxy before correction and the shear force detection value Pxy after correction. The calibration curve is, for example, a linear function represented by the following equation (6). In equation (6), bxy is a sensitivity coefficient that indicates the slope of the calibration curve. Figure 10 shows an example of the calibration curve of equation (6). After correction Pxy = Before correction Pxy / bxy (6)

[0062] In step S5, the detection unit 2 increases the corrected shear force detection value Pxy as the pressing force detection value Pz increases. Specifically, the detection unit 2 changes the sensitivity coefficient bxy in the above-mentioned formula (6) according to the pressing force detection value Pz.

[0063] Figure 11 is an example of a graph showing the correspondence between the detected pressure value Pz and the sensitivity coefficient bxy. In the example in Figure 11, the correspondence between the detected pressure value Pz and the sensitivity coefficient bxy is represented by a linear function expressed by the following equation (7). In equation (7), D is a coefficient that indicates the slope of the graph. In equation (7), E is a coefficient that indicates the intercept of the graph. Coefficient D is a negative value, and coefficient E is a positive value. Coefficients D and E are determined in advance by sensitivity measurement and are stored as fixed values ​​in the memory of the detection unit 2. bxy = D × Pz + E (7)

[0064] Figure 12 is a flowchart showing the detailed procedure of step S5. As shown in Figure 12, in step S5, the detection unit 2 first calculates the sensitivity coefficient bxy based on the detected pressing force value Pz (step S51). Specifically, the sensitivity coefficient bxy is calculated by substituting the detected pressing force value Pz calculated in step S1 into formula (7). As a result, the larger the detected pressing force value Pz, the smaller the sensitivity coefficient bxy can be.

[0065] Next, the detection unit 2 corrects the shear force detection value Pxy using the sensitivity coefficient bxy calculated in step S51 (step S52). Specifically, the detection unit 2 substitutes the shear force detection value Pxy calculated in step S2 and the sensitivity coefficient bxy calculated in step S51 into formula (6). This makes it possible to increase the value of the shear force detection value Pxy as the pressing force detection value Pz increases.

[0066] As described above, the detection device 100 in this modified example corrects the shear force detection value Pxy by considering that the elastic layer 30 becomes less deformable in the x and y directions as it is compressed in the z direction. This allows for a more accurate output of the shear force detection value Pxy.

[0067] <3-2. Second variation> Furthermore, in the above embodiment, considering that the elastic layer 30 becomes less deformable in the x and y directions as it is compressed in the z direction, the unit conversion process increased the shear force conversion value Fxy as the pressing force detection value Pz or pressing force conversion value Fz increased. However, the ease of deformation in the x and y directions when the elastic layer 30 is compressed in the z direction may be variable. In other words, the degree of deformation of the elastic layer 30 may increase or decrease depending on the pressing force.

[0068] <3-3. Third Variation> Furthermore, in the above embodiment, the correspondence between the pressure-converted value Fz and the sensitivity coefficient axy was given by a linear function shown in equation (5). However, this is not the case, for example, when a very high pressure is applied. That is, as the pressure increases, the amount of deformation in the x-axis and y-axis directions may decrease. In such cases, when it is difficult to express the correspondence between the pressure-converted value Fz and the sensitivity coefficient axy as a linear function, the sensitivity coefficient axy may be calculated from, for example, the following equation (8), which is a curved n-th degree function. Also, the correspondence between the pressure-converted value Fz and the sensitivity coefficient axy may include both a linear function part and an n-th degree function part. axy=f(Fz) (8)

[0069] Equation (8) is determined by sensitivity measurement. Even in this case, by storing each of the coefficients of each term in equation f(Fz) as a fixed value in the memory of the detection unit 2, the sensitivity coefficient axy corresponding to the applied pressing force can be calculated.

[0070] <3-4. Other variations> In the embodiments and modifications described above, the calibration curve for shear force in the x-axis direction and the calibration curve for shear force in the y-axis direction were described without distinction. However, the calibration curve for shear force in the x-axis direction and the calibration curve for shear force in the y-axis direction may be prepared separately. Furthermore, the sensitivity coefficient ax for the calibration curve for shear force in the x-axis direction and the sensitivity coefficient ay for the calibration curve for shear force in the y-axis direction may be set to different values.

[0071] Furthermore, the detection unit 2 may detect only one of the shear force in the x-axis direction or the shear force in the y-axis direction.

[0072] Furthermore, the elements that appear in the above embodiments and modifications may be combined or partially deleted, to the extent that no contradictions arise. [Explanation of Symbols]

[0073] 1: Sensor body 2: Detection unit 3: Flexible printed circuit board 4: Detection circuit 10:Support layer 20: Lower electrode layer 21: Lower electrode 30: Elastic layer 40: Upper electrode layer 41: Upper electrode 50: Cover layer 61: First capacitor 62: Second capacitor 100: Detection device C1: Capacitance C2: Capacitance Pz: Pressing force detection value Pxy: Shear force detection value Fz: Converted value of pressing force Fxy: Shear force equivalent value axy: Sensitivity coefficient bxy: Sensitivity coefficient

Claims

1. A detection device for detecting external forces, A sheet-shaped sensor body, The sensor body and the detection unit electrically connected, Equipped with, The sensor body is Elastic layer and A plurality of lower electrodes are arranged on the lower surface of the elastic layer, An upper electrode is positioned on the upper surface of the elastic layer and spans at least two adjacent lower electrodes in a top view, It has, The detection unit is A detection value calculation process that calculates, based on the change in capacitance between the lower electrode and the upper electrode, a pressing force detection value that reflects the pressing force applied in the z-axis direction perpendicular to the surface of the sensor body, and a shear force detection value that reflects the shear force applied in at least one of the x-axis and y-axis directions along the surface of the sensor body, A correction process is performed to correct the shear force detection value according to the pressing force detection value. A correction process is performed to correct the shear force detection value so that it becomes larger as the pressing force detection value increases. A detection device that performs this task.

2. The detection device according to claim 1, wherein the correction process corrects the shear force detection value so that the larger the pressing force detection value, the larger the shear force detection value.

3. The detection unit is The shear force detection value is corrected according to the calibration curve. The detection device according to claim 1, wherein the sensitivity coefficient, which is the slope of the calibration curve, is changed according to the detected pressing force value.

4. A detection device for detecting external forces, A sheet-shaped sensor body, The sensor body and the detection unit electrically connected, Equipped with, The sensor body is Elastic layer and A plurality of lower electrodes are arranged on the lower surface of the elastic layer, An upper electrode is positioned on the upper surface of the elastic layer and spans at least two adjacent lower electrodes in a top view, It has, The detection unit is A detection value calculation process that calculates, based on the change in capacitance between the lower electrode and the upper electrode, a pressing force detection value that reflects the pressing force applied in the z-axis direction perpendicular to the surface of the sensor body, and a shear force detection value that reflects the shear force applied in at least one of the x-axis and y-axis directions along the surface of the sensor body, A unit conversion process that calculates a pressed force equivalent value obtained by converting the pressed force detected value to a predetermined unit and a shear force equivalent value obtained by converting the shear force detected value to the predetermined unit, Execute, A detection device that converts the shear force conversion value according to the pressing force detection value or the pressing force conversion value in the unit conversion process.

5. The detection device according to claim 4, wherein the unit conversion process increases the shear force conversion value as the pressing force detection value or the pressing force conversion value increases.

6. The detection unit is According to the calibration curve, the shear force conversion value is calculated from the detected shear force value. The detection device according to claim 5, wherein the sensitivity coefficient, which is the slope of the calibration curve, is changed according to the detected pressing force value or the converted pressing force value.

7. Let P be the detected shear force value, F be the converted shear force value, and a be the sensitivity coefficient, then the calibration curve is defined as follows: F = P / a The detection device according to claim 6, wherein the linear function is represented by .

8. Let Fz be the converted pressing force value, A be a negative coefficient, and B be a positive coefficient. The relationship between the sensitivity coefficient a and the converted pressing force value Fz is as follows: a = A × Fz + B The detection device according to claim 7, wherein the linear function is represented by .

9. Let the aforementioned pressure conversion value be Fz, and the relationship between the sensitivity coefficient a and the pressure conversion value Fz be, a = f(Fz) The detection device according to claim 7, wherein the nth-degree function is represented by [formula].

10. The detection device according to any one of claims 4 to 9, wherein the detection unit converts the shear force detection value to Newtons in the unit conversion process.

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