Strain detection device
Patent Information
- Application Number
- JP2023011849
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-01-30
- Publication Date
- 2025-07-03
AI Technical Summary
Existing strain detection devices face challenges in maintaining detection accuracy due to temperature differences between the front and back sides of strain gauges, which affect the alignment of wiring resistances and compromise the accuracy of strain detection.
A double-sided strain gauge sensor configuration with first and second sensor sheets facing each other, connected via a flexible base material, where strain gauges on both sides are arranged in opposition and connected through power and ground lines, allowing for differential detection of strain signals to minimize the impact of wiring resistances.
The solution enhances detection accuracy by isolating strain gauge resistance changes from wiring resistances, enabling precise curvature detection with reduced power consumption and improved signal fidelity.
Smart Images
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Abstract
Description
[Technical field]
[0001] An embodiment of the present invention relates to a distortion detection device. [Background technology]
[0002] As an example of a strain detection device, a flexible film- or sheet-shaped strain gauge sensor is known. The strain gauge sensor has strain gauges arranged side by side on the surface of a band-shaped flexible sheet base material, and a plurality of signal lines for passing electricity through these strain gauges (see, for example, Patent Document 1). In addition, in the strain gauge disclosed in Patent Document 2, a plurality of strain gauges are provided on the front and back of the sheet. The strain gauges on the front side are arranged facing the strain gauges on the back side, respectively. The strain gauge sensor is wrapped around a curved object to detect the curved shape of the object by detecting the resistance change of each strain gauge. In this strain gauge sensor, it is difficult to make the wiring resistances, etc., of the strain gauges on the front and back of the sheet uniform due to differences in temperature conditions between the front and back of the sheet, which may adversely affect the accuracy of strain detection. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2013-174514 A [Patent Document 2] Japanese Patent Application Publication No. 60-67804 Summary of the Invention [Problem to be solved by the invention]
[0004] An object of the embodiments of the present invention is to provide a strain detection device capable of improving detection accuracy. [Means for solving the problem]
[0005] The strain detector according to the embodiment includes a flexible substrate having a first main surface and a second main surface opposite to the first main surface, a first sensor sheet provided on the first main surface side, a second sensor sheet provided on the second main surface side and facing the first sensor sheet across the substrate, and a controller for driving the first sensor sheet and the second sensor sheet. Each of the first sensor sheet and the second sensor sheet has one end and the other end, and includes a plurality of strain gauges arranged in a line at intervals, a plurality of power lines and a plurality of first signal lines each extending along the row of the plurality of strain gauges and connected to one end of the strain gauges, and a plurality of ground lines and a plurality of second signal lines each extending along the row of the plurality of strain gauges and connected to the other end of the strain gauges. The plurality of strain gauges of the first sensor sheet are arranged opposite the plurality of strain gauges of the second sensor sheet across the substrate, and the plurality of ground lines of the first sensor sheet are each connected to the plurality of power lines of the second sensor sheet. [Brief description of the drawings]
[0006] [Figure 1] FIG. 1 is a perspective view of a strain gauge sensor device according to an embodiment. [Diagram 2] FIG. 2 is a vertical sectional view of the strain gauge sensor device. [Diagram 3] FIG. 3 is a development view showing a schematic diagram of a gauge pattern and a wiring pattern of a first sensor sheet and a second sensor sheet of the strain gauge sensor device. [Figure 4] FIG. 4 is a block diagram of a controller of the strain gauge sensor device. [Diagram 5] FIG. 5 is a circuit diagram of a differential detection circuit in the analog front end of the controller. [Figure 6] FIG. 6 is a side view showing a schematic diagram of the strain gauge sensor device installed on the surface of a test object. [Figure 7] FIG. 7 is a timing chart of various signals during detection by the strain gauge sensor device. [Figure 8]FIG. 8 is an exploded view of the strain gauge sensor device showing a scanning operation during detection. [Figure 9] FIG. 9 is an exploded view of the strain gauge sensor device showing a scanning operation during detection. [Figure 10] FIG. 10 is a schematic diagram showing a part of the strain gauge sensor device in a state where it is installed on the peripheral surface of a test object. [Figure 11] FIG. 11 is an equivalent circuit diagram of the first and second sensor sheets. [Figure 12] FIG. 12 is a cross-sectional view of a strain gauge sensor device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0007] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are within the spirit of the invention and that can be easily conceived by a person skilled in the art are naturally included in the scope of the present invention. In addition, in order to make the explanation clearer, the width, thickness, shape, etc. of each part may be shown diagrammatically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.
[0008] (Embodiment) As an example of a strain detection device, a strain gauge sensor device according to an embodiment will be described in detail. Fig. 1 is a perspective view of the strain gauge sensor device according to the embodiment. As shown in the figure, the strain gauge sensor device 10 constitutes a double-sided strain gauge sensor. The strain gauge sensor device 10 includes a long and thin strip-shaped flexible base substrate 44 functioning as a base material, a first sensor sheet 20A attached to a first main surface (front surface) of the base substrate 44, a second sensor sheet 20B attached to a second main surface (back surface) of the base substrate 44, a pair of flexible wiring boards (FPCs) 14, and an intermediate substrate (drive circuit substrate) 12 connected to the first sensor sheet 20A and the second sensor sheet 20B via the pair of flexible wiring boards 14. In one example, the base substrate 44 is made of a resin such as polyethylene terephthalate (PET) or polyimide, and has a thickness of about 0.3 to 0.5 mm.
[0009] Each of the first sensor sheet 20A and the second sensor sheet 20B has a long, thin, flexible sheet base material 22 and a conductor pattern provided on one side of the sheet base material 22. The conductor pattern includes a plurality of strain gauges G1 to Gn. The plurality of strain gauges G1 to Gn are arranged side by side in the longitudinal direction X at predetermined intervals from one end to the other end of the longitudinal direction X of the sheet base material 22. In the figure, the longitudinal direction X and the width direction Y of the sensor sheet are two directions that are perpendicular to each other. These directions may intersect at an angle other than 90 degrees.
[0010] FIG. 2 is a vertical cross-sectional view of the strain gauge sensor device 10. As shown in FIG. 2, the base substrate 44 has a front surface and a back surface opposite the front surface. In one example, the surface of the first sensor sheet 20A having the conductor patterns (G1 to Gn) is attached to the front surface of the base substrate 44 by an adhesive layer Ad such as a transparent adhesive sheet (OCA). The surface of the second sensor sheet 20B having the conductor patterns (G1 to Gn) is attached to the back surface of the base substrate 44 by an adhesive layer Ad. The relay board 12 includes a drive circuit 40 and a plurality of wirings provided on one surface side, and a plurality of wirings (not shown) provided on the other surface side. The conductor pattern of the first sensor sheet 20A is connected to the wirings provided on the upper surface side of the relay board 12 via the FPC 14. Similarly, the conductor pattern of the second sensor sheet 20B is connected to the wirings provided on the lower surface side of the relay board 12 via the FPC 14.
[0011] FIG. 3 is a plan view showing the strain gauges and wiring patterns of the first sensor sheet 20A and the second sensor sheet 20B in an unfolded state. As shown in the figure, according to this embodiment, the first sensor sheet 20A and the second sensor sheet 20B are configured to have the same shape, dimensions, and conductor pattern. In detail, each of the first sensor sheet 20A and the second sensor sheet 20B has a flexible band-shaped sheet base material 22 and a conductor pattern provided on one side of the sheet base material 22. The conductor pattern has a plurality of strain gauges G1 to Gn. The plurality of strain gauges G1 to Gn are arranged in a row at intervals in the longitudinal direction X from one end (tip) to the other end (base end) of the longitudinal direction X of the sheet base material 22. Each of the strain gauges G1 to Gn extends in a bellows-like manner in the width direction Y and has one end and the other end in the width direction Y. Each of the strain gauges G1 to Gn produces a change in resistance according to the strain.
[0012] The conductor pattern includes a plurality of power supply lines VL1 to VLn, a plurality of ground lines GNL1 to GNLn, a plurality of first signal lines Sa1 to San, and a plurality of second signal lines Sb1 to Sbn, each extending in the longitudinal direction X along the row of the strain gauges G1 to Gn. The power supply lines VL1 to VLn are located on the side of one end of the strain gauges G1 to Gn. The power supply lines VL1 to VLn have one end connected to one end of the strain gauges G1 to Gn, respectively, and the other end located on the base end side of the sheet substrate 22, and extend substantially parallel to each other. The first signal lines Sa1-San are located between one end of the strain gauges G1-Gn and the power supply lines VL1-VLn. The first signal lines Sa1-San have one end connected to one end of the strain gauges G1-Gn and the other end located on the base end side of the sheet base material 22, and extend substantially parallel to each other. The ground wires GNL1 to GNLn are located on the side of the other ends of the strain gauges G1 to Gn. The ground wires GNL1 to GNLn have one end connected to the other end of the strain gauges G1 to Gn and the other end located on the base end side of the sheet base material 22, and extend approximately parallel to each other. The second signal lines Sb1-Sbn are located between the other ends of the strain gauges G1-Gn and the ground lines GNL1-GNLn. The second signal lines Sb1-Sbn have one end connected to the other end of the strain gauges G1-Gn and the other end located on the base end side of the sheet base material 22, and extend substantially parallel to each other.
[0013] The first sensor sheet 20A and the second sensor sheet 20B configured as described above are attached to the front and rear surfaces of the base substrate 44, and face each other with the base substrate 44 in between. That is, the strain gauges G1 to Gn of the first sensor sheet 20A face the strain gauges G1 to Gn of the second sensor sheet 20B with the base substrate 44 in between. Here, it is preferable that the strain gauges G1 to Gn of the first sensor sheet and the strain gauges G1 to Gn of the second sensor sheet at least partially overlap each other in a plan view seen from a direction perpendicular to the surface of the base substrate 44. Alternatively, it is preferable that the strain gauges G1 to Gn of the sensor sheets 20A and 20B overlap each other without being shifted in the width direction Y while allowing at least a shift in the longitudinal direction X. Alternatively, it is preferable that the strain gauges G1 to Gn of the sensor sheets 20A and 20B overlap each other without being shifted in either the longitudinal direction X or the width direction Y.
[0014] The ground lines GNL1-GNLn of the first sensor sheet 20A extend onto the upper surface of the relay board 12 via the FPC 14. The power lines VL1-VLn of the second sensor sheet 20B extend onto the rear surface of the relay board 12 via the FPC 14. In this embodiment, the ground lines GNL1-GNLn of the first sensor sheet 20A are electrically connected to the power lines VL1-VLn of the second sensor sheet 20B at the position of the relay board 12, that is, short-circuited. As shown in FIG. 2, the ground lines GNL1-GNLn and the power lines VL1-VLn are connected to each other via plated through holes SH formed in the relay board 12 as connection lines. Note that the connection lines are not limited to the plated through holes SH, and may be wiring patterns on the relay board 12 or the like. It is also possible to adopt a configuration in which the FPC 14 on the second sensor sheet 20B side is also connected to the upper surface side of the relay board 12, thereby connecting the ground lines GNL1-GNLn of the first sensor sheet 20A to the power lines VL1-VLn of the second sensor sheet 20B, respectively, via wiring on the relay board 12, rather than via plated through holes. Furthermore, it is also possible to adopt a configuration in which the FPC 14 on the first sensor sheet 20A side and the FPC 14 on the second sensor sheet 20B side are connected to a drive circuit 40 provided on the upper surface side of the relay board 12, and the ground lines GNL1-GNLn of the first sensor sheet 20A are connected to the power lines VL1-VLn of the second sensor sheet 20B, respectively, within the drive circuit 40.
[0015] Next, a drive circuit (controller) for driving the first sensor sheet 20A and the second sensor sheet 20B configured as described above will be described. Fig. 4 is a block diagram showing a schematic diagram of the drive circuit of the strain gauge sensor device 10, and Fig. 5 is a circuit diagram of a difference detection circuit in the analog front end. As shown in FIG. 4, a drive circuit 40 provided on a relay board (control circuit board) 12 includes a selector SEL, an analog front end (AFE: signal conditioning circuit) 30, a timing controller 34, a communication interface 36, and the like.
[0016] The communication interface 36 is connected to an external host controller 38 wirelessly or via a wire, receives a driving signal (setting) from the host controller 38, and transmits detection data (Data) to the host controller 38. The timing controller 34 outputs a drive signal to the selector SEL and the analog front end 30 in response to a drive signal (setting). The selector SEL is composed of a plurality of shift registers, multiplexers, etc. In response to a drive signal from the timing controller 34, the selector SEL sequentially connects the power supply lines VL1-VLn of the first sensor sheet 20A to a power supply, and sequentially applies a voltage to the strain gauges G1-Gn. In synchronization with this, the selector SEL1 sequentially reads the detection signals (voltage values) RXa1-RXan, RXb1-RXbn of one end side and the other end side of each of the strain gauges G1-Gn via the first signal lines Sa1-San and the second signal lines Sb1-Sbn. Furthermore, in synchronization with the above reading, the selector SEL sequentially reads the detection signals (voltage values) RXc1-RXcn, RXd1-RXdn of one end side and the other end side of each of the strain gauges G1-Gn via the first signal lines Sa1-San and the second signal lines Sb1-Sbn of the second sensor sheet 20B.
[0017] The analog front end 30 includes a read circuit 31, difference detection circuits 30a and 30b, an AD converter 32, a digital filter 33, a memory 37, and the like (see FIG. 8). As shown in FIG. 5, according to this embodiment, the analog front end 30 includes a difference detection circuit (subtraction circuit) 30a that processes the detection signal of the first sensor sheet 20A, and a difference detection circuit (subtraction circuit) 30b that processes the detection signal of the second sensor sheet 20B. The analog front end 30 performs signal conditioning (amplification, AD conversion, filtering) on the detection signals RXa, RXb and detection signals RXc, RXd of the strain gauges G1 to Gn sent from the selector SEL in response to the drive signal, and outputs the signals to the communication interface 36. At this time, since the voltage drop value of each strain gauge G is required to calculate the radius of curvature, the difference between the detection values Rxa, Rxb of the respective strain gauges G1 to Gn and the difference between the detection values Rxc, Rxd of the respective strain gauges G1 to Gn are calculated by the difference detection circuits 30a and 30b, and output the signals. The host controller 38 reads the output signal (data) sent from the communication interface 36, performs arithmetic processing such as data shaping and curved surface calculation, and calculates the distortion, curvature, etc. of the subject detected by the first and second sensor sheets 20A, 20B.
[0018] Next, the detection operation mode of the strain gauge sensor device 10 will be described. Figure 6 is a schematic diagram showing the state in which the first sensor sheet and the second sensor sheet are placed on the surface of a subject, Figure 7 is a timing chart showing the signal output when operating in the detection operation mode, and Figures 8 and 9 are plan views showing schematic views of the scanning operation of the strain gauge sensor device. 6, the strain gauge sensor device 10 is installed by wrapping it around a peripheral surface 50a of a test object 50 to detect the curved shape of the peripheral surface 50a. In this case, the strain gauge sensor device 10 is installed with the second sensor sheet 20B side in contact with the peripheral surface 50a.
[0019] In the detection operation mode, the power supply lines and signal lines are scan-driven to sequentially drive the strain gauges G1-Gn and sequentially read the detection values of the strain gauges G1-Gn. In detail, as shown in Fig. 7, during detection, the timing controller 34 inputs a start signal VD and a clock signal HD synchronous with the start signal VD to the selector SEL in response to an instruction from the host controller 38, and sequentially drives (sets) the strain gauges G1-Gn of the first and second sensor sheets 20A and 20B in one frame period.
[0020] 8, the selector SEL drives the power line VL1 of the first sensor sheet 20A, i.e., applies a power supply voltage to the power line VL1 and applies a desired voltage PW1 to the strain gauge G1. This causes a current I to flow through the strain gauge G1 for a certain period of time. At the same time, the selector SEL acquires a detection signal (voltage value) RXa1 from one end of the strain gauge G1 and a detection signal (voltage value) RXb1 from the other end of the strain gauge G1 via a first signal line Sa1 and a second signal line Sb1. The ground line GNL1 of the first sensor sheet 20A is connected to the power line VL1 of the second sensor sheet 20B. More specifically, the strain gauge G1 of the first sensor sheet 20A and the strain gauge G1 of the second sensor sheet 20B are connected in series via the ground line GNL1 of the first sensor sheet 20A, a connection line (plated through hole), and the power line VL1 of the second sensor sheet 20B. Therefore, when the strain gauge G1 of the first sensor sheet 20A is driven, the strain gauge G1 of the second sensor sheet 20B is driven in synchronization, and the current I is also passed through the strain gauge G1. At the same time, the selector SEL acquires a detection signal (voltage value) RXc1 of one end of the strain gauge G1 and a detection signal (voltage value) RXd1 of the other end of the strain gauge G1 via the first signal line Sa1 and the second signal line Sb1 of the second sensor sheet 20B. The acquired detection signals RXa1, RXb1, RXc1, and RXd1 are sent to the analog front end 30, where they are adjusted and subjected to difference detection, and then stored in the memory 37.
[0021] As shown in FIG. 9, the selector SEL then drives the power line VL2 of the first sensor sheet 20A, i.e., applies a power supply voltage to the power line VL2, and applies a desired voltage PW2 to the strain gauge G2 of the first sensor sheet 20A and the strain gauge G2 of the second sensor sheet 20B, respectively. This causes a current I to flow through the two opposing strain gauges G2 for a certain period of time. At the same time, the selector SEL acquires a detection signal RXa2 from one end of the strain gauge G2 and a detection signal RXb2 from the other end of the strain gauge G2 via the first signal line Sa2 and the second signal line Sb2 of the first sensor sheet 20A. At the same time, the selector SEL acquires a detection signal RXc2 from one end of the strain gauge G2 and a detection signal RXd2 from the other end of the strain gauge G2 via the first signal line Sa2 and the second signal line Sb2 of the second sensor sheet 20B. The acquired detection signals RXa2, RXb2, RXc2, and RXd2 are sent to the analog front end 30, where they are adjusted and subjected to difference detection, and then stored in the memory 37.
[0022] Thereafter, the selector SEL sequentially drives the strain gauges G3-Gn of the first sensor sheet 20A and the strain gauges G3-Gn of the second sensor sheet 20B, and sequentially acquires the detection signals RXa3-RXan, RXb3-RXbn, RXc3-RXcn, and RXd3-RXdn of the strain gauges G3-Gn. The acquired detection signals are sequentially sent to the analog front end 30, adjusted and subjected to difference detection, and then stored in the memory 37.
[0023] As described above, the analog front end 30 sequentially reads out the transmitted detection signals RXa1-RXan, RXb1-RXbn, and detection signals RXc1-RXcn, RXd1-RXdn by the readout circuit 31, converts them into voltage signals, and further converts them into digital data by the AD converter 32 and the digital filter 33. Furthermore, the analog front end 30 detects the differences between the detection signals RXa1-RXan and RXb1-RXbn, and the differences between the detection signals RXc1-RXcn and RXd1-RXdn by the difference detection circuits 30a and 30b. The detected difference data is sequentially stored in the memory 37. When the scan for one frame period is completed, the analog front end 30 reads out the difference data for one frame from the memory 37 and outputs it to the host controller 38. The host controller 38 calculates the curved surface shape of the peripheral surface 50a of the subject 50 based on the transmitted data.
[0024] A method for calculating the shape of a curved surface, for example, the radius of curvature, will now be described. 10 is a schematic diagram of a part of the strain gauge sensor device installed on the peripheral surface 50a of the subject 50 described above. As shown in the figure, when installed on the peripheral surface 50a, the neutral surface of the base substrate 44 is curved with the same radius of curvature r as the peripheral surface 50a. Here, the neutral surface is a surface where no expansion or contraction occurs before or after bending of the strain gauge sensor (i.e., where the strain is zero even after bending). In this embodiment, the neutral surface is provided at a position that is the center (thickness×½) in the thickness direction of the base substrate 44. The strain gauge Ga of the first sensor sheet 20A located on the outer periphery side and the strain gauge Gb of the second sensor sheet 20B located on the inner periphery side face each other in the radial direction and are curved with different radii of curvature.
[0025] In FIG. 10 and the formula below, W0: initial width of the strain gauge, Wa: width of the strain gauge on the outer periphery, Wb: width of the strain gauge on the inner periphery, ΔW: change in width of the strain gauge, d: thickness of the substrate, θ: opening angle of the strain gauge, r: radius of curvature of the neutral plane, k: gauge factor, R0: reference resistance of the strain gauge, and ΔR: change in resistance of the strain gauge.
[0026] If the width of the strain gauge G on the neutral surface of the base substrate 44 is the initial width W0 of the strain gauge, then W0 = rθ. The strain gauge Ga on the outer periphery is deformed into an elongated state by being curved, and its gauge width Wa is
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[0027] FIG. 11 is a diagram showing a schematic equivalent circuit of the first sensor sheet 20A and the second sensor sheet 20B. As shown in the figure, in this embodiment, the ground line GNL of the first sensor sheet 20A is connected to the power line VL of the second sensor sheet 20B, i.e., short-circuited. This connects the outer circumferential strain gauge Ga and the inner circumferential strain gauge Gb in series. When detecting strain, the voltage drop is measured at one end and the other end of each of the strain gauges Ga and Gb. Let R0 be the initial resistance value of each strain gauge Ga, Gb before deformation, Ra be the resistance value of the outer peripheral strain gauge Ga after deformation, Rb be the resistance value of the inner peripheral strain gauge Gb after deformation, V1 and V2 be the voltage values at one end and the other end of the outer peripheral strain gauge Ga, V3 and V4 be the voltage values at one end and the other end of the inner peripheral strain gauge Gb, ΔR be the change in resistance of the strain gauge, and I be the current flowing through each strain gauge Ga, Gb. Then, the voltage drop V12 between one end and the other end of the strain gauge Ga and the voltage drop V34 between one end and the other end of the strain gauge Gb are given by,
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[0028] Applying the above relational expression to the aforementioned calculation formula (1) for the radius of curvature r, we get the following.
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[0029] According to the strain gauge sensor device 10 according to the first embodiment configured as above, the strain gauges G1-Gn of the first sensor sheet and the strain gauges G1-Gn of the second sensor sheet are arranged facing each other with the base material sandwiched therebetween, and further, by shorting the power line of the first sensor sheet and the ground line of the second sensor sheet, the strain gauges of the first sensor sheet and the strain gauges of the second sensor sheet are connected in series. Therefore, the strain gauges G1-Gn of the second sensor sheet can be sequentially driven (scanned) in synchronization with the sequential driving (scanning) of the strain gauges G1-Gn of the first sensor sheet, and the same part can be simultaneously detected by the two strain gauges facing each other on the front and back. Furthermore, during detection, a constant current I can be applied to the two opposing strain gauges, and by taking the difference in detection signals of both strain gauges, it becomes possible to detect the curved surface shape with high accuracy. As described above, the strain gauge sensor device 10 can detect only the resistance changes of the strain gauges G1-Gn, and the detected signal does not include elements other than the resistance changes of the strain gauges (such as the wiring resistance between the power supply and the strain gauges), which makes it possible to improve detection accuracy. Also, by configuring the multiple strain gauges G1-Gn to be driven (scanned) sequentially from one end of the strain gauge row to the other end, power consumption during detection can be reduced compared to when all of the multiple strain gauges are driven simultaneously. As described above, according to this embodiment, it is possible to obtain a strain detection device capable of improving detection accuracy.
[0030] Next, a strain gauge sensor device according to a modified example will be described. In the modified examples described below, the same parts as those in the above-described embodiment are given the same reference numerals as those in the embodiment, and detailed descriptions thereof may be simplified or omitted. (Modification) 12 is a cross-sectional view of the first and second sensor sheets in a strain gauge sensor device according to a modified example. As shown in the figure, according to the modified example, the first sensor sheet 20A has a sheet substrate 22 attached to the front surface of the base substrate 44 by an adhesive layer Ad such as a transparent adhesive sheet (OCA). A protective film PF is laminated on the side of the conductor patterns (G1 to Gn) of the first sensor sheet 20A. The second sensor sheet 20B has a sheet base material 22 attached to the rear surface of the base substrate 44 by an adhesive layer Ad such as a transparent adhesive sheet (OCA). A protective film PF is laminated on the side of the conductor patterns (G1 to Gn) of the second sensor sheet 20B. In the modified example, other configurations of the strain gauge sensor device are the same as those of the strain gauge sensor device according to the above-described embodiment. The strain gauge sensor device according to the modified example can also obtain the same effects as those of the above-described embodiment.
[0031] Although the embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The new embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. All configurations that can be implemented by a person skilled in the art through appropriate design modifications based on the respective configurations described above as the embodiments of the present invention belong to the scope of the present invention as long as they include the gist of the present invention.
[0032] For example, the direction in which the strain gauges are scanned is not limited to the direction from the tip-side strain gauge G1 to the base-side strain gauge Gn, but may be the opposite direction, from the base-side strain gauge Gn to the tip-side strain gauge G1. The connection line connecting the power supply line and the ground line is not limited to a plated through hole, but may be formed by wiring within the selector SEL as shown in FIG. In addition, the number of strain gauges arranged in the sensor sheet is not limited to the above-described embodiment and can be selected arbitrarily. The constituent materials, dimensions, and shape of the sensor sheet are not limited to the above-described embodiment and can be changed as appropriate. [Explanation of symbols]
[0033] 10... strain gauge sensor device, 12... relay board, 20A... first sensor sheet, 20B: second sensor sheet; 22: sheet base material; 30a, 30b: difference detection circuit; 44...Base board, G1~Gn...Strain gauge, VL...Power line, GNL...Ground line, Sa: first signal line, Sb: second signal line, SEL: selector
Claims
1. A flexible substrate having a first main surface and a second main surface facing the first main surface, A first sensor sheet provided on the first main surface side, A second sensor sheet provided on the second main surface side and facing the first sensor sheet with the substrate interposed therebetween, A controller for driving the first sensor sheet and the second sensor sheet, comprising: The first sensor sheet and the second sensor sheet, A plurality of strain gauges having a first end portion and a second end portion located on the opposite side of the first end portion, and arranged in a row with a space therebetween, A plurality of power lines, a plurality of ground lines, a plurality of first signal lines, and a plurality of second signal lines, each having a portion extending along the row of the plurality of strain gauges, Each of the plurality of power lines is connected to one corresponding first end portion of the plurality of strain gauges, Each of the plurality of first signal lines is connected to one corresponding first end portion of the plurality of strain gauges, Each of the plurality of ground lines is connected to one corresponding second end portion of the plurality of strain gauges, Each of the plurality of second signal lines is connected to one corresponding second end portion of the plurality of strain gauges, Each of the plurality of strain gauges of the first sensor sheet is arranged to face one corresponding strain gauge of the plurality of strain gauges of the second sensor sheet with the substrate interposed therebetween, Each of the plurality of ground lines of the first sensor sheet is connected to one corresponding power line of the plurality of power lines of the second sensor sheet. A strain detection device.
2. The controller sequentially applies a power supply voltage to the plurality of power lines of the first sensor sheet, synchronously drives the plurality of strain gauges of the first sensor sheet and the plurality of strain gauges of the second sensor sheet sequentially, and includes a selector for sequentially acquiring detection signals of the first end portion and the second end portion of the strain gauges from the first signal line and the second signal line. The strain detection device according to claim 1.
3. The controller includes a first difference detection circuit for detecting a difference between a detection signal of the first end portion and a detection signal of the second end portion of the strain gauge of the first sensor sheet, and a second difference detection circuit for detecting a difference between a detection signal of the first end portion and a detection signal of the second end portion of the strain gauge of the second sensor sheet. The strain detection device according to claim 1.
4. The controller drives the plurality of strain gauges sequentially from one end side to the other end side of the plurality of columns of strain gauges, the strain detection device according to claim 2.
5. The controller includes a circuit board connected to the wiring of the first sensor sheet and the wiring of the second sensor sheet, the circuit board having a connection line connecting the ground line of the first sensor sheet and the power line of the second sensor sheet, the strain detection device according to claim 1.
6. The controller includes a circuit board connected to the wiring of the first sensor sheet and the wiring of the second sensor sheet, the selector being provided on the circuit board and having a wiring connecting the ground line of the first sensor sheet and the power line of the second sensor sheet, the strain detection device according to claim 2.
7. A base material having a first main surface and a second main surface facing the first main surface, A first sensor sheet provided on the first main surface side, A second sensor sheet provided on the second main surface side, comprising: The first sensor sheet, Having a first end portion and a second end portion located on the opposite side of the first end portion, a plurality of first strain gauges arranged in a row, A plurality of first power lines, a plurality of first ground lines, a plurality of first signal lines, and a plurality of second signal lines, Each of the plurality of first power lines is connected to a corresponding one of the first end portions of the plurality of first strain gauges, Each of the plurality of first signal lines is connected to a corresponding one of the first end portions of the plurality of first strain gauges, Each of the plurality of first ground lines is connected to a corresponding one of the second end portions of the plurality of first strain gauges, Each of the plurality of second signal lines is connected to a corresponding one of the second end portions of the plurality of first strain gauges, The second sensor sheet includes a plurality of second strain gauges arranged in a row and a plurality of second power lines, Each of the plurality of second strain gauges is connected to a corresponding one of the second power lines, Each of the plurality of first ground lines is connected to a corresponding one of the plurality of second power lines, a strain detection device.
8. The plurality of first power lines, the plurality of first ground lines, the plurality of first signal lines, and the plurality of second signal lines have portions extending along the row of the plurality of first strain gauges, the strain detection device according to claim 7.
9. The strain detection device according to claim 7, wherein each of the plurality of first strain gauges faces a corresponding one of the plurality of second strain gauges.
10. further comprising a controller, wherein the controller sequentially applies a power supply voltage to the plurality of first power supply lines, synchronizes each of the plurality of first strain gauges with a corresponding one of the plurality of second strain gauges, and sequentially drives the plurality of first strain gauges and the plurality of second strain gauges. The strain detection device according to claim 7.
11. The controller includes a selector that sequentially acquires a plurality of detection signals detected by the plurality of first strain gauges, wherein each of the plurality of first strain gauges detects a first detection signal supplied to the selector via a corresponding one of the plurality of first signal lines and a second detection signal supplied to the selector via a corresponding one of the plurality of second signal lines. The strain detection device according to claim 10.
12. further comprising a circuit board, wherein the circuit board has a plurality of wirings connecting the plurality of first ground lines and the plurality of second power supply lines, and the selector is located on the circuit board. The strain detection device according to claim 11.
13. each of the plurality of first strain gauges detects a first detection signal output to a corresponding one of the plurality of first signal lines and a second detection signal output to a corresponding one of the plurality of second signal lines, and has a differential detection circuit that detects a difference between the first detection signal and the second detection signal. The strain detection device according to claim 7.
14. further comprising a circuit board, wherein the circuit board has a plurality of wirings connecting the plurality of first ground lines and the plurality of second power supply lines. The strain detection device according to claim 7.