Detection device

Abstract

To provide a technique that enables accurate detection of the curved surface shape of a surface of a measurement object by using a single detection device, even when the measurement object has a surface in the shape with the rapidly changing curvature radius.SOLUTION: In a detection device, a second strain gauge element GB of a second strain gauge CDB and a third strain gauge element GC of a third strain gauge CDC are arranged symmetrically from the central position in the thickness direction Z of a substrate and are superimposed with each other in plan view. A first strain gauge element GA of a first strain gauge CDA and a fourth strain gauge element GD of a fourth strain gauge CDD are arranged symmetrically from the central position in the thickness direction Z of the substrate and are superimposed with each other in plan view. In plan view, the first strain gauge element GA and the second strain gauge element GB deviate from each other in the longitudinal direction X of the substrate. Also, in plan view, the third strain gauge element GC and the fourth strain gauge element GD deviate from each other in the longitudinal direction X of the substrate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a detection device.

Background Art

[0002] As a detection device, there is a strain detection device. As an example of a strain detection device, a flexible film-shaped or sheet-shaped strain gauge sensor is known. The strain gauge sensor has strain gauges (strain gauge elements) arranged side by side on the surface of a strip-shaped flexible sheet base material, and a plurality of signal lines for energizing these strain gauges. In addition, a plurality of strain gauges are provided on both the front and back surfaces of the sheet. The strain gauges on the front surface side are arranged opposite to the strain gauges on the back surface side. By winding the strain gauge sensor around a curved object (measurement target) on the surface and detecting the resistance change of each strain gauge, the curved shape of the surface of the object can be detected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of this disclosure is to provide a technique that enables a single detection device to accurately detect the curved shape of the surface of a measurement target even when the measurement target has a surface with a shape having a large change in the radius of curvature.

Means for Solving the Problems

[0005] The detection device according to the present disclosure is a strip-shaped flexible substrate, A first strain gauge including a plurality of first strain gauge elements provided on the substrate and arranged in a row at a predetermined interval in the length direction of the substrate; A second strain gauge including a plurality of second strain gauge elements provided on the substrate and arranged in a row at a predetermined interval in the length direction of the substrate; A third strain gauge including a plurality of third strain gauge elements provided on the substrate and arranged in a row at a predetermined interval in the length direction of the substrate; A fourth strain gauge including a plurality of fourth strain gauge elements provided on the substrate and arranged in a row at a predetermined interval in the length direction of the substrate; A detection circuit connected to each of the first to fourth strain gauge elements; Each of the first to fourth strain gauges is arranged on the substrate via an insulating layer such that the extending direction of the first to fourth strain gauges is along the length direction of the substrate; The first to fourth strain gauges are laminated in the thickness direction of the substrate in this order such that the extending directions of the first to fourth strain gauges are the same; The second strain gauge element and the third strain gauge element are symmetrically arranged from the central position in the thickness direction of the substrate and overlap in plan view; The first strain gauge element and the fourth strain gauge element are symmetrically arranged from the central position in the thickness direction of the substrate and overlap in plan view; In plan view, the first strain gauge element and the second strain gauge element are displaced in the length direction of the substrate; In plan view, the third strain gauge element and the fourth strain gauge element are displaced in the length direction of the substrate.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0007] Hereinafter, embodiments of this disclosure will be described in detail with reference to the drawings. It should be noted that the present disclosure is merely an example, and for those skilled in the art, appropriate modifications that maintain the gist of the present disclosure and can be easily conceived are naturally included in the scope of the present disclosure. In addition, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is merely an example and does not limit the interpretation of the present disclosure. Also, in this specification and each drawing, the same reference numerals may be assigned to the same elements as those described above with respect to the previously presented drawings, and detailed descriptions may be omitted as appropriate.

[0008] (Embodiment) As an example of the detection device, the strain gauge sensor device 10 according to the embodiment will be described in detail. FIG. 1 is a perspective view of the strain gauge sensor device according to the embodiment.

[0009] As shown in FIG. 1, the strain gauge sensor device 10 as the detection device constitutes a double-sided strain gauge sensor. The strain gauge sensor device 10 includes an elongated strip-shaped flexible base substrate 44 that functions as a base material, a first sensor sheet 20A attached to the first main surface (front surface) of the base substrate 44, a second sensor sheet 20B attached to the second main surface (back surface) of the base substrate 44, a pair of flexible printed circuit boards (FPCs) 14, and a relay substrate (drive circuit board) 12 connected to the first sensor sheet 20A and the second sensor sheet 20B via the pair of flexible printed circuit boards 14. In one example, the base substrate 44 is an insulating layer and is formed of a resin such as polyethylene terephthalate (PET) or polyimide to a thickness of about 0.3 to 0.5 mm.

[0010] Each of the first sensor sheet 20A and the second sensor sheet 20B has, as shown in FIG. 2 described later, an elongated strip-shaped flexible sheet base material 22 made of an insulating layer and two layers of conductor patterns (sensor patterns) CDA, CDB (CDC, CDD) provided on the sheet base material 22. Each layer of the sensor pattern includes a plurality of strain gauges G0 to Gn. The plurality of strain gauges G0 to Gn are arranged in a row in the longitudinal direction X at a predetermined interval from one end to the other end of the sheet base material 22 in the longitudinal direction X. The longitudinal direction X may be referred to as the length direction X. Also, the base substrate 44 and the sheet base material 22 may be collectively referred to as the substrate (44, 22).

[0011] Here, the strain gauges G0 to Gn can be rephrased as a plurality of strain gauge element sheets G0 to Gn. The sensor patterns CDA, CDB, CDC, CDD can be rephrased as the first strain gauge CDA, the second strain gauge CDB, the third strain gauge CDC, and the fourth strain gauge CDD.

[0012] As shown schematically in cross-section in FIG. 1, the first sensor sheet 20A includes the first strain gauge CDA and the second strain gauge CDB, and the second sensor sheet 20B includes the third strain gauge CDC and the fourth strain gauge CDD. The plurality of first strain gauge elements G0 to Gn of the first strain gauge CDA are provided in a row at a predetermined interval L in the length direction X of the base substrate 44 or the sheet base material 22. Similarly, the plurality of second strain gauge elements G0 to Gn of the second strain gauge CDB, the plurality of third strain gauge elements G0 to Gn of the third strain gauge CDC, and the plurality of fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD are also provided in a row at a predetermined interval L in the length direction X of the base substrate 44 or the sheet base material 22. In this example, each of the first to fourth strain gauge elements G0 to Gn has a plurality of corresponding strain gauge elements G0 to Gn arranged at equal intervals (here, a predetermined interval L) in the length direction X of the substrate. The predetermined interval L can be rephrased as the arrangement interval L.

[0013] Each of the first to fourth strain gauges CDA to CDD is disposed via an insulating layer on the base substrate 44 or the sheet base material 22 such that the extending direction of the first to fourth strain gauges CDA to CDD is along the length direction X of the substrate (44, 22). Then, the first to fourth strain gauges CDA, CDB, CDC, and CDD are laminated in the thickness direction Z of the substrate (44, 22) in this order so that the extending directions (length direction X) of the first to fourth strain gauges CDA to CDD are the same. The thickness direction Z will be described with reference to FIG. 2 described later.

[0014] A plurality of second strain gauge elements G0 to Gn of the second strain gauge CDB and a plurality of third strain gauge elements G0 to Gn of the third strain gauge CDC are symmetrically arranged from the central position C (see FIG. 3) in the thickness direction Z of the substrate (44, 22) and overlap in a plan view. Also, a plurality of first strain gauge elements G0 to Gn of the first strain gauge CDA and a plurality of fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD are symmetrically arranged from the central position C in the thickness direction Z of the substrate (44, 22) and overlap in a plan view.

[0015] In a plan view, a plurality of first strain gauge elements G0 to Gn of the first strain gauge CDA and a plurality of second strain gauge elements G0 to Gn of the second strain gauge CDB are arranged shifted in the length direction X of the substrate (44, 22). Also, in a plan view, a plurality of third strain gauge elements G0 to Gn of the third strain gauge CDC and a plurality of fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD are shifted in the length direction X of the substrate (44, 22). In the cross-sectional view of FIG. 1, a plurality of first strain gauge elements G0 to Gn of the first strain gauge CDA and a plurality of second strain gauge elements G0 to Gn of the second strain gauge CDB are arranged shifted by 1 / 2 of the arrangement interval L in the length direction X of the substrate (44, 22). Similarly, a plurality of third strain gauge elements G0 to Gn of the third strain gauge CDC and a plurality of fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD are arranged shifted by 1 / 2 of the arrangement interval L in the length direction X of the substrate (44, 22). That is, although the plan view is omitted, the strain gauge sensor device 10 can be regarded as one strain gauge sensor device in which a plurality of gauge elements are arranged in a line along the length direction X at an arrangement interval of L / 2 in a plan view seen from a direction perpendicular to the surface of the substrate (44, 22). Thereby, even when the measurement object has a surface with a shape having a large change in the radius of curvature, the surface shape of the object to be measured can be accurately specified by one strain gauge sensor device 10 in which the arrangement interval of the gauge elements is made narrower than the arrangement interval L between adjacent gauge elements and is L / 2.

[0016] Regarding the position C, it will be described with reference to FIG. 3 described later. Also, the position C can be regarded as the position of the neutral plane N described with reference to FIG. 10 described later. In FIG. 1, the longitudinal direction X and the width direction Y of the sensor sheet indicate two directions orthogonal to each other. These directions may intersect at an angle other than 90 degrees.

[0017] FIG. 2 is a longitudinal sectional view of the strain gauge sensor device 10.

[0018] As shown in FIG. 2, the base substrate 44 has a front surface (or upper surface) and a back surface (or lower surface) facing the front surface. In one example, the first sensor sheet 20A is attached to the front surface of the base substrate 44 by an adhesive layer Ad such as a transparent adhesive sheet (optically clear adhesive: OCA). The second sensor sheet 20B is attached to the back surface of the base substrate 44 by the adhesive layer Ad.

[0019] The relay substrate 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 first sensor pattern CDA and the second sensor pattern CDB of the first sensor sheet 20A are connected to the wirings provided on the upper surface side of the relay substrate 12 via the FPC 14. Similarly, the third sensor pattern CDC and the fourth sensor pattern CDD of the second sensor sheet 20B are connected to the wirings provided on the lower surface side of the relay substrate 12 via the FPC 14. The drive circuit 40 can be referred to as a detection circuit.

[0020] FIG. 3 is a cross-sectional view of the strain gauge sensor device along lines A-A and B-B in FIG. 2. Note that the lines A-A and B-B in FIG. 2 correspond to the lines A-A and B-B in the cross-sectional view of FIG. 1. In FIG. 3, a cross-sectional view along line A-A is shown on the left side, and a cross-sectional view along line B-B is shown on the right side. FIG. 4 is a longitudinal sectional view of the strain gauge sensor device according to a modified example.

[0021] As shown in FIG. 3, the first sensor sheet 20A includes a flexible belt-like sheet base material 22, a first sensor pattern CDA (G0 to Gn) provided on one surface of the sheet base material 22, a first insulating layer IL1 laminated on the sheet base material 22 so as to overlap the first sensor pattern CDA, a second sensor pattern CDB (G0 to Gn) provided on the first insulating layer IL1, a second insulating layer IL2 laminated on the first insulating layer IL1 so as to overlap the second sensor pattern CDB, and a protective layer (surface protection film) PTL provided on the second insulating layer IL2. In one example, the sheet base material 22 is formed of polyimide, and the first and second insulating layers IL1 and IL2 are formed of silicon nitride (SiN). In one example, the first sensor sheet 20A is joined to the base substrate 44 by an adhesive layer Ad on the side of the protective layer TPL.

[0022] Similarly, the second sensor sheet 20B includes a flexible belt-like sheet base material 22, a fourth sensor pattern CDD provided on one surface of the sheet base material 22, a first insulating layer IL1 laminated on the sheet base material 22 so as to overlap the fourth sensor pattern CDD, a third sensor pattern CDC provided on the first insulating layer IL1, a second insulating layer IL2 laminated on the first insulating layer IL1 so as to overlap the third sensor pattern CDC, and a protective layer (surface protection film) PTL provided on the second insulating layer IL2. In one example, the sheet base material 22 is formed of polyimide, and the first and second insulating layers IL1 and IL2 are formed of silicon nitride (SiN). In one example, the second sensor sheet 20B is joined to the base substrate 44 by an adhesive layer Ad on the side of the protective layer TPL.

[0023] The entirety of the base substrate 44, the adhesive layer Ad, the first sensor sheet 20A, and the second sensor sheet 20B will be described as the substrate 11. Also, the strain gauges (first strain gauge elements G0 to Gn) of the first sensor pattern CDA will be referred to as the first strain gauge GA, the strain gauges (second strain gauge elements G0 to Gn) of the second sensor pattern CDB will be referred to as the second strain gauge GB, the strain gauges (third strain gauge elements G0 to Gn) of the third sensor pattern CDC will be referred to as the third strain gauge GC, and the strain gauges (fourth strain gauge elements G0 to Gn) of the fourth sensor pattern CDD will be referred to as the fourth strain gauge GD.

[0024] As shown in the cross-sectional view along the line A-A on the left side of FIG. 3, the first strain gauge GA and the fourth strain gauge GD are disposed to face each other in the thickness direction Z of the base material 11 with the insulating layers (IL1, IL2), the protective layer TPL, the adhesive layer Ad, and the base substrate 44 interposed therebetween. In other words, the first strain gauge GA and the fourth strain gauge GD are symmetrically disposed from the central position C in the thickness direction Z of the substrate 11 and overlap in a plan view.

[0025] Also, as shown in the cross-sectional view along the line B-B on the right side of FIG. 3, the second strain gauge GB and the third strain gauge GC are disposed to face each other in the thickness direction Z of the base material 11 with the insulating layers (IL1, IL2), the protective layer TPL, the adhesive layer Ad, and the base substrate 44 interposed therebetween. In other words, the inner second strain gauge GB and the third strain gauge GC are symmetrically disposed from the central position C in the thickness direction Z of the substrate 11 and overlap in a plan view. When the central position C in the thickness direction Z of the base material 11 is taken as the center line C, the outer first strain gauge GA and the fourth strain gauge GD are symmetrically disposed with respect to the center line C, and the inner second strain gauge GB and the third strain gauge GC are symmetrically disposed with respect to the center line C.

[0026] That is, when the distance between the outer first strain gauge GA and the center line C is the first interval d1, the distance between the outer fourth strain gauge GD and the center line C is the second interval d2, the distance between the inner second strain gauge GB and the center line C is the third interval d3, and the distance between the inner third strain gauge GC and the center line C is the fourth interval d4, it is desirable that the first interval d1 and the second interval d2 be equal (d1 = d2), and that the third interval d3 and the fourth interval d4 be equal (d3 = d4). It is also possible that d1 ≠ d3 and d2 ≠ d4.

[0027] In the substrate 11, the first sensor sheet 20A and the second sensor sheet 20B may each be configured to be joined to the base substrate 44 by the adhesive layer Ad with the protective layer PTL side. Also, as shown in FIG. 4, the base substrate 44 may be omitted, and the first sensor sheet 20A and the second sensor sheet 20B may be bonded to each other by an adhesive layer Ad such as a transparent adhesive sheet (OCA). The configuration of the strain gauge sensor device 10 shown in FIG. 4 is the same as the configuration of the strain gauge sensor device 10 shown in FIG. 2 except that the base substrate 44 is omitted, so duplicate explanations are omitted.

[0028] FIG. 5 is a developed view schematically showing the strain gauges and wirings of the second sensor pattern CDB of the first sensor sheet 20A and the third sensor pattern CDC of the second sensor sheet 20B, and FIG. 6 is a perspective view schematically showing the laminated structure of the first sensor pattern CDA and the second sensor pattern CDB in the first sensor sheet 20A.

[0029] As shown in FIG. 5, according to the present embodiment, the first sensor sheet 20A and the second sensor sheet 20B are configured to have the same shape, dimensions, and sensor pattern. The pattern configuration will be described by taking the second sensor pattern CDB of the first sensor sheet 20A and the third sensor pattern CDC of the second sensor sheet 20B as representatives. Each of the second sensor pattern CDB and the third sensor pattern CDC has a plurality of strain gauges G0 to Gn. The plurality of strain gauges G0 to Gn are arranged in a row at intervals of L 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 G0 to Gn extends in a bellows shape or a rectangular wave shape in the width direction Y and has one end and the other end in the width direction Y. Each of the strain gauges G0 to Gn has the same desired resistance value in a state where there is no strain in each of the strain gauges G0 to Gn. Each of the strain gauges G0 to Gn has its resistance value changed according to the strain and generates a resistance change in a state where there is strain in each of the strain gauges G0 to Gn. That is, in a state where there is no strain, the resistance value of the second strain gauge element GB and the resistance value of the third strain gauge element GC are configured to be the same, and the resistance value of the first strain gauge element GA and the resistance value of the fourth strain gauge element GD are configured to be the same. On the other hand, in a state where there is strain, the resistance value of the second strain gauge element GB and the resistance value of the third strain gauge element GC are configured to be different, and the resistance value of the first strain gauge element GA and the resistance value of the fourth strain gauge element GD are configured to be different.

[0030] Each of the sensor patterns CDB and CDC has a plurality of power lines VL0 to VLn, a plurality of ground lines GNL0 to GNLn, a plurality of first signal lines Sa0 to San, and a plurality of second signal lines Sb0 to Sbn that extend in the longitudinal direction X along the rows of the strain gauges G0 to Gn. The plurality of ground lines GNL0 to GNLn are connected so that a first reference potential such as a ground potential (GND: 0V) is applied, and the plurality of power lines VL0 to VLn are connected so that a second reference potential (power supply potential) higher than the first reference potential is applied.

[0031] The power lines VL0 to VLn are located on one end side of the strain gauges G0 to Gn. The power lines VL0 to VLn each have one end connected to one end of the strain gauges G0 to Gn and the other end located on the proximal end side of the sheet base material 22, and extend substantially parallel to each other.

[0032] The first signal lines Sa0 to San are located between one end of the strain gauges G0 to Gn and the power lines VL0 to VLn. The first signal lines Sa0 to San each have one end connected to one end of the strain gauges G0 to Gn and the other end located on the proximal end side of the sheet base material 22, and extend substantially parallel to each other.

[0033] The ground lines GNL0 to GNLn are located on the other end side of the strain gauges G0 to Gn. The ground lines GNL0 to GNLn each have one end connected to the other end of the strain gauges G0 to Gn and the other end located on the proximal end side of the sheet base material 22, and extend substantially parallel to each other.

[0034] The second signal lines Sb0 to Sbn are located between the other end of the strain gauges G0 to Gn and the ground lines GNL0 to GNLn. The second signal lines Sb0 to Sbn each have one end connected to the other end of the strain gauges G0 to Gn and the other end located on the proximal end side of the sheet base material 22, and extend substantially parallel to each other.

[0035] As will be described later, in this embodiment, the ground lines GNL0 to GNLn of the second sensor pattern CDB are each electrically connected to the power lines VL0 to VLn of the third sensor pattern CDC via the connection metal in the through hole SH at the position of the relay substrate 12. Thereby, each strain gauge of the second sensor pattern CDB is connected in series to each strain gauge of the third sensor pattern.

[0036] In other words, in the second strain gauge CDB and the third strain gauge CDC, a corresponding one of the second strain gauge elements GB and a corresponding one of the third strain gauge elements GC are connected in series such that one end thereof is connected to the first reference potential (for example, ground potential: 0 V), and the other end is connected to a second reference potential higher than the first reference potential (for example, power supply potential: +nV). Similarly, in the first strain gauge CDA and the fourth strain gauge CDD, a corresponding one of the first strain gauge elements GA and a corresponding one of the fourth strain gauge elements GD are connected in series such that one end thereof is connected to the first reference potential (for example, ground potential: 0 V), and the other end is connected to the second reference potential (for example, power supply potential: +nV).

[0037] As shown in FIGS. 2 and 3, in the first sensor sheet 20A, the first sensor pattern CDA (G0 to Gn) is formed on the sheet base material 22, and the first insulating layer IL1 is laminated on the sheet base material 22 so as to overlap the first sensor pattern CDA. The second sensor pattern CDB is formed on the first insulating layer IL1, and the second insulating layer IL2 is laminated on the first insulating layer IL1 so as to overlap the second sensor pattern CDB.

[0038] As shown in FIG. 6, the strain gauges G0 to Gn of the second sensor pattern CDB are each displaced by 1 / 2 of the arrangement interval L in the thickness direction of the first sensor pattern CDA and the first sensor sheet 20A (see also FIG. 1).

[0039] The power supply lines VL0 to VLn, ground lines GNL0 to GNLn, first signal lines Sa0 to San, and second signal lines Sb0 to Sbn of the second sensor pattern CDB are each slightly displaced in the width direction Y with respect to the power supply lines VL0 to VLn, ground lines GNL0 to GNLn, first signal lines Sa0 to San, and second signal lines Sb0 to Sbn of the first sensor pattern CDA.

[0040] The power lines VL0 to VLn, ground lines GNL0 to GNLn, first signal lines Sa0 to San, and second signal lines Sb0 to Sbn of the second sensor pattern CDB each have a tip-side portion DA connected to the strain gauges G0 to Gn and a base-side portion PA extending from the middle part to the base end of the sheet base material 22. Each tip-side portion DA is provided on the first insulating layer IL1, and the base-side portion PA is provided on the sheet base material 22. The ends of the respective tip-side portions DA are electrically connected to the ends of the base-side portion PA via connection wirings CM formed in contact holes provided in the first insulating layer IL1.

[0041] Thus, the base-side portions PA of the power lines VL0 to VLn, ground lines GNL0 to GNLn, first signal lines Sa0 to San, and second signal lines Sb0 to Sbn of the second sensor pattern CDB are located in the same plane as the power lines VL0 to VLn, ground lines GNL0 to GNLn, first signal lines Sa0 to San, and second signal lines Sb0 to Sbn of the first sensor pattern CDA, that is, are located on the sheet base material 22 and are connected to the wirings of the common FPC14.

[0042] The third sensor pattern CDC and the fourth sensor pattern CDD of the second sensor sheet 20B are formed in the same shape, the same dimensions, and the same structure as the first sensor pattern CDA and the second sensor pattern CDB of the first sensor sheet 20A shown in FIG. 6.

[0043] That is, in a plan view, the first strain gauge elements G0 to Gn of the first strain gauge CDA and the second strain gauge elements G0 to Gn of the second strain gauge CDB are displaced in the length direction X of the substrate 11 (44, 22), and the amount of displacement is 1 / 2 of the arrangement interval L in this example. Similarly, in a plan view, the third strain gauge elements G0 to Gn of the third strain gauge CDC and the fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD are displaced in the length direction X of the substrate 11 (44, 22), and the amount of displacement is 1 / 2 of the arrangement interval L in this example.

[0044] As shown in FIG. 2, the first sensor sheet 20A and the second sensor sheet 20B configured as described above are attached to the front and back surfaces of the base substrate 44 and face each other with the base substrate 44 interposed therebetween. That is, the first strain gauge elements G0 to Gn of the first strain gauge CDA of the first sensor sheet 20A face the fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD of the second sensor sheet 20B with the base substrate 44 interposed therebetween. The second strain gauge elements G0 to Gn of the second strain gauge CDB of the first sensor sheet 20A face the third strain gauge elements G0 to Gn of the third strain gauge CDC of the second sensor sheet 20B with the base substrate 44 interposed therebetween.

[0045] Here, it is preferable that a part of the first strain gauge elements G0 to Gn of the first sensor sheet 20A and a part of the fourth strain gauge elements G0 to Gn of the second sensor sheet 20B overlap each other in a plan view seen from a direction perpendicular to the surface of the base substrate 44. Also, it is preferable that a part of the second strain gauge elements G0 to Gn of the first sensor sheet 20A and a part of the third strain gauge elements G0 to Gn of the second sensor sheet 20B overlap each other in a plan view seen from a direction perpendicular to the surface of the base substrate 44. The first strain gauge elements G0 to Gn of the first sensor sheet 20A and the fourth strain gauge elements G0 to Gn of the second sensor sheet 20B preferably overlap each other in the plan view seen from a direction perpendicular to the surface of the base substrate 44 while allowing displacement in the longitudinal direction X and without displacement in the width direction Y. Also, the second strain gauge elements G0 to Gn of the first sensor sheet 20A and the third strain gauge elements G0 to Gn of the second sensor sheet 20B preferably overlap each other in the plan view seen from a direction perpendicular to the surface of the base substrate 44 while allowing displacement in the longitudinal direction X and without displacement in the width direction Y. Alternatively, it is more preferable that the first strain gauge elements G0 to Gn of the first sensor sheet 20A and the fourth strain gauge elements G0 to Gn of the second sensor sheet 20B overlap each other without displacement in both the longitudinal direction X and the width direction Y in the plan view seen from a direction perpendicular to the surface of the base substrate 44. Also, it is more preferable that the second strain gauge elements G0 to Gn of the first sensor sheet 20A and the third strain gauge elements G0 to Gn of the second sensor sheet 20B overlap each other without displacement in both the longitudinal direction X and the width direction Y in the plan view seen from a direction perpendicular to the surface of the base substrate 44.

[0046] The wirings of the first sensor pattern CDA and the second sensor pattern CDB of the first sensor sheet 20A extend up to the upper surface of the relay substrate 12 via the FPC 14. The wirings of the third sensor pattern CDC and the fourth sensor pattern CDD of the second sensor sheet 20B extend up to the back surface of the relay substrate 12 via the FPC 14. In the present embodiment, the ground lines GNL0 to GNLn of the first sensor pattern CDA are electrically connected to the power lines VL0 to VLn of the fourth sensor pattern CDD by the plated-through holes SH as connection lines formed in the relay substrate 12, respectively. Further, the ground lines GNL0 to GNLn of the second sensor pattern CDB are electrically connected to the power lines VL0 to VLn of the third sensor pattern CDC by the plated-through holes SH as connection lines formed in the relay substrate 12, respectively.

[0047] Note that the connection lines are not limited to the plated-through holes SH, and wiring patterns on the relay substrate 12 or the like may be used. Also, by connecting the FPC 14 on the side of the second sensor sheet 20B to the upper surface side of the relay substrate 12, it is also possible to adopt a configuration in which the ground lines GNL0 to GNLn of the first sensor sheet 20A are respectively connected to the power lines VL0 to VLn of the second sensor sheet 20B via wiring on the relay substrate 12 instead of the plated-through holes. Furthermore, it is also possible to adopt a configuration in which the FPC 14 on the side of the first sensor sheet 20A and the FPC 14 on the side of the second sensor sheet 20B are connected to the drive circuit 40 provided on the upper surface side of the relay substrate 12, and the ground lines GNL0 to GNLn of the first sensor sheet 20A are respectively connected to the power lines VL0 to VLn of the second sensor sheet 20B within the drive circuit 40.

[0048] FIG. 7 is a diagram for explaining the strain gauge sensor device 10 according to a modified example. FIG. 7 depicts a schematic cross-sectional view of the strain gauge sensor device 10 and a diagram for explaining the concept of the modified example. Note that in FIG. 7, the illustrations of the relay substrate 12 and the drive circuit 40 described in FIG. 2 are omitted for simplification of the drawing, but actually, as shown in FIG. 2, the relay substrate 12 and the drive circuit 40 are provided.

[0049] As shown on the upper side of FIG. 7, the strain gauge sensor device 10 includes a first sensor substrate 101, a second sensor substrate 102, a third sensor substrate 103, a fourth sensor substrate 104, and an adhesive layer Ad such as a transparent adhesive sheet (OCA). The adhesive layer Ad is used for connecting the first sensor substrate 101 and the second sensor substrate 102, connecting the second sensor substrate 102 and the third sensor substrate 103, and connecting the third sensor substrate 103 and the fourth sensor substrate 104. The entire first sensor substrate 101, second sensor substrate 102, third sensor substrate 103, fourth sensor substrate 104, and adhesive layer Ad can be regarded as an elongated strip-shaped flexible substrate 11. The longitudinal direction X and the width direction Y of the substrate 11 are the same as those in FIG. 1. The longitudinal direction X and the width direction Y indicate two directions perpendicular to each other. The directions X and Y may intersect at an angle other than 90 degrees.

[0050] On the first sensor substrate 101, a first strain gauge CDA and an FPC14 connected to the first strain gauge CDA are arranged. On the second sensor substrate 102, a second strain gauge CDB and an FPC14 connected to the second strain gauge CDB are arranged. On the third sensor substrate 103, a third strain gauge CDC and an FPC14 connected to the third strain gauge CDC are arranged. On the fourth sensor substrate 104, a fourth strain gauge CDD and an FPC14 connected to the fourth strain gauge CDD are arranged. Here, each of the first sensor substrate 101, second sensor substrate 102, third sensor substrate 103, and fourth sensor substrate 104 can be said to be a single resistance change type curved surface sensor having the same shape, the same dimensions, and the same configuration manufactured by a sheet process.

[0051] As shown on the lower side of FIG. 7, in the first sensor substrate 101, second sensor substrate 102, third sensor substrate 103, and fourth sensor substrate 104, a plurality of strain gauges G0 to Gn are arranged in a row at intervals of the arrangement interval L in the longitudinal direction X from one end (tip) to the other end (base end) in the longitudinal direction X of the base material 11.

[0052] The case of assembling the strain gauge sensor device 10 using the first sensor substrate 101, the second sensor substrate 102, the third sensor substrate 103, and the fourth sensor substrate 104 will be described. As shown on the lower side of FIG. 7, the first sensor substrate 101 and the second sensor substrate 102 are arranged with a shift in the length direction X of the substrate 11. Similarly, the third sensor substrate 103 and the fourth sensor substrate 104 are arranged with a shift in the length direction X of the substrate 11. In this example, the amount of shift between the first sensor substrate 101 and the second sensor substrate 102 in the length direction X of the substrate 11, that is, the amount of shift between the first strain gauge element G1 - G0 of the first strain gauge CDA and the second strain gauge element G0 - Gn of the second strain gauge CDB in a plan view, is set to 1 / 2 of the arrangement interval L of adjacent strain gauge elements. The amount of shift between the third sensor substrate 103 and the fourth sensor substrate 104, that is, the amount of shift between the third strain gauge element G1 - G0 of the third strain gauge CDC and the fourth strain gauge element G0 - Gn of the fourth strain gauge CDD in a plan view, is also set to 1 / 2 of the arrangement interval L of adjacent strain gauge elements.

[0053] In this way, a plurality of sheets of one type of resistance change type curved surface sensor are created to form the first sensor substrate 101, the second sensor substrate 102, the third sensor substrate 103, and the fourth sensor substrate 104. Then, when adhering the created first sensor substrate 101, second sensor substrate 102, third sensor substrate 103, and fourth sensor substrate 104 using the adhesive layer Ad, for example, it is done as follows.

[0054] 1) The first sensor substrate 101 and the second sensor substrate 102 are attached using the adhesive layer Ad so as to be arranged with a shift of 1 / 2 of the arrangement interval L of the strain gauge elements G0 - Gn in the length direction X of the substrate 11. It is preferable that the width direction Y of the substrate 11 coincides between the first sensor substrate 101 and the second sensor substrate 102.

[0055] 2) The third sensor substrate 103 and the fourth sensor substrate 104 are attached using the adhesive layer Ad so as to be displaced by 1 / 2 of the arrangement interval L of the strain gauge elements G0 - Gn in the length direction X of the substrate 11. It is preferable that the width direction Y of the substrate 11 coincides between the third sensor substrate 103 and the fourth sensor substrate 104.

[0056] 3) In a plan view, the second sensor substrate 102 and the third sensor substrate 103 are attached using the adhesive layer Ad so that the first strain gauge elements G0 - Gn of the first sensor substrate 101 and the fourth strain gauge elements G0 - Gn of the fourth sensor substrate 104 overlap, and also so that the second strain gauge elements G0 - Gn of the second sensor substrate 102 and the third strain gauge elements G0 - Gn of the third sensor substrate 103 overlap.

[0057] Thereby, a plurality of sheets of one type of resistive change type curved surface sensor are created using a sheet process (a plurality of identical sensor substrates are created), and the bonding of these resistive change type curved surface sensors is contrived as in the above 1) - 3). Thereby, even for a measurement object having a shape with a drastically changing radius of curvature depending on the location, or for a measurement object having a complex shape, it becomes possible to accurately measure the shape using one strain gauge sensor device 10. Thereby, the reproducibility of the object shape of the measurement object can be improved. Also, according to this configuration, since it is only necessary to design one type of resistive change type curved surface sensor, the design cost of the resistive change type curved surface sensor can be reduced. Also, since it is only necessary to create a plurality of sheets of one type of resistive change type curved surface sensor (identical sensor substrates), it is possible to relatively easily and with good yield perform the creation work of a plurality of sheets of resistive change type curved surface sensors. Therefore, the manufacturing cost of the resistive change type curved surface sensor can be reduced. Furthermore, by performing a relatively simple alignment, one strain gauge sensor device 10 can be created, so the manufacturing cost of the strain gauge sensor device 10 can be reduced. Also, there is no need to remake the strain gauge sensor device 10 depending on the application used (for example, the magnitude of the radius of curvature of the measurement object).

[0058] Next, a drive circuit 40 for driving the first sensor sheet 20A and the second sensor sheet 20B configured as described above will be described. The drive circuit 40 may also be referred to as a controller or a detection circuit. FIG. 8 is a block diagram schematically showing the drive circuit of the strain gauge sensor device 10, and FIG. 9 is a plan view showing the first to fourth sensor patterns and the analog front end of the controller of the strain gauge sensor device in a scan operation at the time of detection, and is a block diagram showing the first to fourth sensor patterns, the selector of the controller, and the analog front end. In FIG. 9, for simplicity of the drawing, the power supply lines VL0 to VLn of each sensor pattern are shown bundled into one power supply line, and the ground lines GNL0 to GNLn are shown bundled into one power supply line.

[0059] As shown in FIG. 8, the drive circuit 40 provided on the relay substrate (control circuit substrate) 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.

[0060] The communication interface 36 is wirelessly or wiredly connected to an external host controller 38, receives a drive signal (setting) from the host controller 38, and transmits detection data (Data) to the host controller 38.

[0061] The timing controller 34 outputs drive signals to the selector SEL and the analog front end 30 according to the drive signal (setting).

[0062] The selector SEL is composed of a plurality of shift registers, multiplexers, etc. The selector SEL sequentially connects the power supply lines VL0 to VLn of the first and second sensor patterns CDA and CDB in the first sensor sheet 20A to the power supply according to the drive signal from the timing controller 34, and sequentially applies voltages Pw0 to Pwn to the strain gauges G0 to Gn. In synchronization with this, the selector SEL sequentially reads the detection signals (voltage values) Rxa0 to Rxan and Rxb0 to Rxbn at one end side and the other end side of each strain gauge G0 to Gn via the first signal lines Sa0 to San and the second signal lines Sb0 to Sbn.

[0063] The voltages Pw0 to Pwn supplied to the power supply lines VL0 to VLn of the first and second sensor patterns CDA and CDB are sequentially applied to the power supply lines VL0 to VLn of the third and fourth sensor patterns CDC and CDD via the ground lines GNL0 to GNLn and the connection line SH. The selector SEL sequentially reads the detection signals (voltage values) Rxc0 to Rxcn and Rxd0 to Rxdn at one end side and the other end side of each strain gauge G0 to Gn via the first signal lines Sa0 to San and the second signal lines Sb0 to Sbn in the second sensor sheet 20B in synchronization with the above reading.

[0064] As shown in FIG. 9, the analog front end 30 includes a differential detection circuit 30a, 30b, a read circuit 31, an AD converter 32, a digital filter 33, a memory 37, and the like. As shown in FIG. 9, according to this embodiment, the analog front end 30 includes a differential detection circuit (subtraction circuit) 30a that processes the detection signal of the first sensor sheet 20A, and a differential detection circuit (subtraction circuit) 30b that processes the detection signal of the second sensor sheet 20B. The analog front end 30 signal - adjusts (amplifies, AD - converts, filters) the detection signals Rxa, Rxb of each strain gauge G0 to Gn and the detection signals Rxc, Rxd sent from the selector SEL in response to the drive signal, and outputs them to the communication interface 36. At this time, since the voltage drop value of each strain gauge G is required for calculating the radius of curvature, the first and second differential detection circuits 30a, 30b take the difference between the detection values Rxa, Rxb of each strain gauge G0 to Gn and the difference between the detection values Rxc, Rxd of each strain gauge G0 to Gn, respectively, and output signals.

[0065] As shown in FIG. 8, the host controller 38 includes a read circuit 38a, a memory 38b, an arithmetic processing unit 38c, a storage device 38d, and the like. The read circuit 38a reads the output signal (differential data) sent from the communication interface 36 and stores it in the memory 38b. The arithmetic processing unit 38c, for example, a central processing unit (CPU), performs arithmetic processing such as data shaping and surface calculation based on the differential data, and calculates the strain (radius of curvature), surface form (surface coordinates), etc. of the object detected by the first and second sensor sheets 20A, 20B. The memory 38b stores differential data, the calculated radius of curvature, surface form, detection operation program, and the like. The storage device 38d is used, for example, as the working area of the CPU.

[0066] Next, the detection operation mode of the strain gauge sensor device 10 will be described.

[0067] FIG. 10 is a diagram schematically showing an enlarged part of a strain gauge sensor device 10 installed on a surface 50a of a subject 50. In one example, the subject 50 as a measurement object has a surface 50a curved in a wavy or sine wave shape. The strain gauge sensor device 10 is installed in close contact with the surface 50a of the subject 50 to detect the curved form of the subject 50. Thereby, the shape of the object that is the subject 50 can be specified. In this case, the strain gauge sensor device 10 is installed in a state where the second sensor sheet 20B is in contact with the surface 50a of the subject 50. Also, in one example, each sensor pattern of the first sensor sheet 20A and the second sensor sheet 20B is assumed to include about 4 to 8 strain gauges G0 to Gn. The interval L between adjacent strain gauges is, for example, about 5 to 20 mm, more preferably about 10 to 15 mm.

[0068] As shown in FIG. 10, in a state of being installed on the surface 50a, it is assumed that the neutral plane N of the substrate 11 is curved with a radius of curvature r. Here, the neutral plane N is a plane in which neither elongation (tension) nor contraction (compression) occurs before and after the bending of the strain gauge sensor device 10 (that is, a plane with zero strain even after bending). In the present embodiment, it is assumed that the neutral plane N is at a position C that is the center in the thickness direction of the base substrate 44 (thickness × 1 / 2) (see FIG. 3).

[0069] The strain gauge (which may be referred to as the first strain gauge) GA of the first sensor pattern CDA in the first sensor sheet 20A located on the outer peripheral side and the strain gauge (which may be referred to as the fourth strain gauge) GD of the fourth sensor pattern CDD of the second sensor sheet 20B face each other in the radial direction (thickness direction Z) with an insulating layer interposed therebetween. The strain gauge (which may be referred to as the second strain gauge) GB of the second sensor pattern CDB in the first sensor sheet 20A located on the inner peripheral side and the strain gauge (which may be referred to as the third strain gauge) GC of the third sensor pattern CDC of the second sensor sheet 20B face each other in the radial direction (thickness direction Z) with an insulating layer interposed therebetween. That is, among the four strain gauges GA, GB, GC, and GD laminated in four layers, GA and GD are spaced apart in the radial direction and face each other, and GB and GC face each other. The strain gauge GA is located on the outermost periphery, the strain gauge GD is located on the innermost periphery, and between them, two layers of strain gauges GB and GC are located. When the interval d in the thickness direction Z between the two opposing layers of strain gauges is made constant (the interval between GA and GB = d, the interval between GB and GC = d, the interval between GC and GD = d), the thickness of the substrate 11 of the strain gauge sensor device 10 is 3d. When the neutral plane N is a flat plane, that is, in a state where there is no strain in the second strain gauge element GB and the third strain gauge element GC, and the first strain gauge element GA and the fourth strain gauge element GD, the resistance value (initial resistance value: R0') of the second strain gauge element GB and the resistance value (initial resistance value: R0') of the third strain gauge element GC are configured to be the same. Similarly, the resistance value (initial resistance value: R0) of the first strain gauge element GA and the resistance value (initial resistance value: R0) of the fourth strain gauge element GD are configured to be the same. On the other hand, in a state where there is strain in the second strain gauge element GB and the third strain gauge element GC, and the first strain gauge element GA and the fourth strain gauge element GD, the resistance value (R0'+ΔR0', or R0'-ΔR0') of the second strain gauge element GB and the resistance value (R0'-ΔR0', or R0'+ΔR0') of the third strain gauge element GC are configured to be different. Similarly, the resistance value (R0+ΔR0, or R0-ΔR0) of the first strain gauge element GA and the resistance value (R0-ΔR0, or R0+ΔR0) of the fourth strain gauge element GD are configured to be different.Here, +ΔR0 and +ΔR0’ indicate the change in resistance value when the strain gauge element is in a state of extending in the longitudinal direction X (or in an extended state, a tensile state), and -ΔR0 and -ΔR0’ indicate the change in resistance value when the strain gauge element is in a state of contracting in the longitudinal direction X (or in a contracted state, a compressive state).

[0070] When the distance between the outermost strain gauge GA and the neutral plane N is d1, the distance between the innermost strain gauge GD and the neutral plane N is d2, the distance between the intermediate strain gauge GB and the neutral plane N is d3, and the distance between the intermediate strain gauge GC and the neutral plane N is d4, it is desirable that d1 = d2 and d3 = d4. It is also possible that d1 ≠ d3 and d2 ≠ d4.

[0071] In the detection operation mode, by scanning and driving the power line and the signal line, the strain gauges G0 to Gn are sequentially driven, and the detection values of the strain gauges G0 to Gn are sequentially read. Specifically, at the time of detection, the timing controller 34 inputs a start signal and a clock signal synchronized therewith to the selector SEL in response to an instruction from the host controller 38, and drives (sets) the strain gauges G0 to Gn of the first and second sensor sheets 20A and 20B sequentially within one frame period.

[0072] As shown in FIG. 9, the selector SEL first applies a voltage to the two outermost strain gauges GA and GD to perform strain detection. The selector SEL drives the power line VL0 of the first sensor pattern CDA, that is, applies a power supply voltage to the power line VL0 to apply a desired voltage Pw0 to the strain gauge G0. As a result, a current I is passed through the strain gauge G0 for a certain period of time. At the same time, the selector SEL acquires the detection signal (voltage value) Rxa0 at one end of the strain gauge G0 and the detection signal (voltage value) Rxb0 at the other end of the strain gauge G0 via the first signal line Sa0 and the second signal line Sb0.

[0073] The ground line GNL0 of the first sensor pattern CDA is connected to the power line VL0 of the fourth sensor pattern CDD of the second sensor sheet 20B. More specifically, the strain gauge G0 (GA) of the first sensor pattern CDA and the strain gauge G0 (GD) of the fourth sensor pattern CDD are connected in series via the ground line GNL0 of the first sensor pattern CDA, the connection line (plated through hole) SH, and the power line VL0 of the fourth sensor pattern CDD. Therefore, when the strain gauge G0 of the first sensor pattern CDA is driven, the strain gauge G0 of the fourth sensor pattern CDD is driven synchronously, and current I is also passed through the strain gauge G0. At the same time, the selector SEL acquires the detection signal (voltage value) Rxc0 at one end of the strain gauge G0 and the detection signal (voltage value) Rxd0 at the other end of the strain gauge G0 via the first signal line Sa0 and the second signal line Sb0 of the fourth sensor pattern CDD.

[0074] The acquired detection signals Rxa0, Rxb0, Rxc0, and Rxd0 are sent to the analog front end 30, where differential detection of the detection values Rxa and Rxb, differential detection of the detection values Rxc and Rxd, and adjustment are performed, and then they are stored in the memory 37.

[0075] Next, the selector SEL drives the power line VL1 of the first sensor pattern CDA and applies a desired voltage Pw1 to the strain gauge G1 of the first sensor pattern CDA and the strain gauge G1 of the fourth sensor pattern CDD, respectively. As a result, current I is passed through the two opposing strain gauges G1 for a certain period of time. At the same time, the selector SEL acquires the detection signal Rxa1 at one end of the strain gauge G1 and the detection signal Rxb1 at the other end of the strain gauge G1 via the first signal line Sa1 and the second signal line Sb1 of the first sensor pattern CDA. At the same time, the selector SEL acquires the detection signal Rxc1 at one end of the strain gauge G1 and the detection signal Rxd1 at the other end of the strain gauge G1 via the first signal line Sa1 and the second signal line Sb1 of the fourth sensor pattern CDD.

[0076] The obtained detection signals Rxa1, Rxb1, Rxc1, and Rxd1 are sent to the analog front end 30, differentially detected and adjusted by the differential detection circuits 30a and 30b, and then stored in the memory 37.

[0077] Thereafter, the selector SEL sequentially drives the strain gauges G2 to Gn of the first sensor pattern CDA and the strain gauges G2 to Gn of the fourth sensor pattern CDD, and sequentially acquires the detection signals Rxa2 to Rxan, Rxb2 to Rxbn, Rxc2 to Rxcn, and Rxd2 to Rxdn of the strain gauges G2 to Gn. The acquired detection signals are sequentially sent to the analog front end 30, adjusted and differentially detected, and then stored in the memory 37.

[0078] As shown in FIG. 11, next, the selector SEL applies a voltage to the two strain gauges GB and GC located in the intermediate layer (inside) to perform strain detection. In FIG. 11, for the sake of simplicity of the drawing, the power lines VL0 to VLn of each sensor pattern are shown collectively as one power line, and the ground lines GNL0 to GNLn are shown collectively as one power line.

[0079] Specifically, the selector SEL drives the power line VL0 of the second sensor pattern CDB of the first sensor sheet 20A and applies a desired voltage Pw0 to the strain gauge G0. Thereby, a current I is passed through the strain gauge G0 for a certain period of time. At the same time, the selector SEL acquires the detection signal (voltage value) Rxa0 at one end of the strain gauge G0 and the detection signal (voltage value) Rxb0 at the other end of the strain gauge G0 via the first signal line Sa0 and the second signal line Sb0.

[0080] The ground line GNL0 of the second sensor pattern CDB is connected to the power line VL0 of the third sensor pattern CDC of the second sensor sheet 20B. More specifically, the strain gauge G0 (GB) of the second sensor pattern CDB and the strain gauge G0 (GC) of the third sensor pattern CDC are connected in series via the ground line GNL0 of the second sensor pattern CDB, the connection line (plated through hole) SH, and the power line VL0 of the third sensor pattern CDC. Therefore, when the strain gauge G0 of the second sensor pattern CDB is driven, the strain gauge G0 of the third sensor pattern CDC is driven synchronously, and current I is also passed through the strain gauge G0. At the same time, the selector SEL acquires the detection signal (voltage value) Rxc0 at one end of the strain gauge G0 and the detection signal (voltage value) Rxd0 at the other end of the strain gauge G0 via the first signal line Sa0 and the second signal line Sb0 of the third sensor pattern CDC.

[0081] The acquired detection signals Rxa0, Rxb0, Rxc0, and Rxd0 are sent to the analog front end 30, where differential detection of the detection values Rxa and Rxb, differential detection of the detection values Rxc and Rxd, and adjustment are performed, and then stored in the memory 37.

[0082] Next, the selector SEL drives the power line VL1 of the second sensor pattern CDB and applies a desired voltage Pw1 to the strain gauge G1 of the second sensor pattern CDB and the strain gauge G1 of the third sensor pattern CDC, respectively. As a result, current I is passed through the two opposing strain gauges G1 for a certain period of time. At the same time, the selector SEL acquires the detection signal Rxa1 at one end of the strain gauge G1 and the detection signal Rxb1 at the other end of the strain gauge G1 via the first signal line Sa1 and the second signal line Sb1 of the second sensor pattern CDB. At the same time, the selector SEL acquires the detection signal Rxc1 at one end of the strain gauge G1 and the detection signal Rxd1 at the other end of the strain gauge G1 via the first signal line Sa1 and the second signal line Sb1 of the third sensor pattern CDC.

[0083] The acquired detection signals Rxa1, Rxb1, Rxc1, and Rxd1 are sent to the analog front end 30, differentially detected and adjusted by the differential detection circuits 30a and 30b, and then stored in the memory 37.

[0084] Thereafter, the selector SEL sequentially drives the strain gauges G2 to Gn of the second sensor pattern CDB and the strain gauges G2 to Gn of the third sensor pattern CDD, and sequentially acquires the detection signals Rxa2 to Rxan, Rxb2 to Rxbn, Rxc2 to Rxcn, and Rxd2 to Rxdn of the strain gauges G2 to Gn. The acquired detection signals are sequentially sent to the analog front end 30, adjusted and differentially detected, and then stored in the memory 37.

[0085] As described above, the analog front end 30 sequentially reads out the sent detection signals Rxa1 to Rxan, Rxb1 to Rxbn, and the detection signals Rxc1 to Rxcn, Rxd1 to Rxdn by the readout circuit 31, converts them into voltage signals, and further converts them into digital data (Data) by the AD converter 32 and the digital filter 33. Further, the analog front end 30 detects the difference between the detection signals Rxa0 to Rxan and Rxb0 to Rxbn and the difference between the detection signals Rxc0 to Rxcn and Rxd0 to Rxdn by the differential detection circuits 30a and 30b. The detected differential 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 differential data for one frame from the memory 37 and outputs it to the host controller 38. The host controller 38 calculates the curved surface form of the surface 50a of the subject 50 based on the sent data.

[0086] Hereinafter, a method for calculating the curved surface form, specifically, the radius of curvature in one example, will be described.

[0087] FIG. 12 is a diagram for explaining a surface form in which the radius of curvature and surface coordinates calculated based on the detected values of strain gauges GA and GD and the detected values of strain gauges GB and GC are plotted at the positions of a plurality of strain gauges G0 to Gn (in FIG. 12, as an example, n = 0 to 3) of the strain gauge sensor device 10. Here, the outer strain gauges GA and GD face each other in the radial direction (the thickness direction of the base material) and are curved with different radii of curvature. Further, the inner strain gauges GB and GC face each other in the radial direction (the thickness direction of the base material) and are curved with different radii of curvature.

[0088] In the following mathematical formulas, 3d: thickness of the base material, θn, θn’: bending angle, rn, rn’: radius of curvature of the neutral plane N, k: gauge factor, R0, R0’: strain gauge reference resistance (initial resistance value), ΔR0, ΔR0’: strain gauge resistance change (resistance value change amount) are shown respectively. Further, the following calculations are performed by, for example, the host controller 38.

[0089] First, the case of calculating the radius of curvature based on the detected values of the strain gauges GA and GD will be described.

[0090] Assuming that the length of the strain gauge at the neutral plane N of the substrate 11 is the initial length of the strain gauge, the outer intermediate strain gauge GA is deformed by the elongation or contraction of the length in the longitudinal direction X due to bending, and the inner intermediate strain gauge GD is deformed in the opposite way to the strain gauge GA, that is, the length in the longitudinal direction X is contracted or extended due to bending. Here, as an example, as shown in FIG. 10, consider the case where the outermost strain gauge GA is deformed to a state where the length in the longitudinal direction X is extended due to bending, and the innermost strain gauge GD is deformed to a state where the length in the longitudinal direction X is contracted due to bending.

[0091] Let the initial resistance values of the strain gauges GA and GD before deformation be R0, the potential difference between both ends of the deformed strain gauge GA (the difference between the voltage value at one end of the gauge and the voltage value at the other end) be VA, the potential difference between both ends of the deformed strain gauge GD be VD, the resistance change of the strain gauge be ΔR0, and the current flowing through each of the strain gauges GA and GD be I. Then, the potential difference VA of the strain gauge GA and the potential difference VD of the strain gauge GD are VA = (R0 + ΔR0) × I VD = (R0 - ΔR0) × I It becomes as follows. Expressing the relationship with the potential difference across each strain gauge using the change in strain gauge resistance results in the following equations. (VD / VA) = (R0 - ΔR0) / (R0 + ΔR0) From the above equation, the change rate of the strain gauge resistance is calculated by the following equation. (ΔR0 / R0) = (VD - VA) / (VD + VA) From the above relational expressions, the calculation formula for the radius of curvature rn of the neutral plane N is rn = (3kd / 2) × (R0 / ΔR0) It becomes as follows.

[0092] Next, the case of calculating the radius of curvature based on the detection values of the strain gauges GB and GC will be described. As shown in FIG. 10, when the length of the strain gauge on the neutral plane N of the substrate 11 is taken as the initial strain gauge length, the strain gauge GB on the intermediate outer side is deformed by curving, causing the length in the longitudinal direction X to extend or contract, and the strain gauge GC on the intermediate inner side is deformed in the opposite way to the strain gauge GB by curving, causing the length in the longitudinal direction X to contract or extend. Here, as an example, as shown in FIG. 10, consider the case where the strain gauge GB on the intermediate outer side is deformed into a state where the length in the longitudinal direction X has extended by curving, and the strain gauge GC on the intermediate inner side is deformed into a state where the length in the longitudinal direction X has contracted by curving.

[0093] Let the initial resistance values of the strain gauges GB and GC before deformation be R0', the potential difference across the strain gauge GB after deformation (the difference between the voltage value at one end of the gauge and the voltage value at the other end) be VB, the potential difference across the strain gauge GC after deformation be VC, the resistance change of the strain gauge be ΔR0', and the current flowing through each of the strain gauges GB and GC be I'. Then, the potential difference VB of the strain gauge GB and the potential difference VC of the strain gauge GC are VB = (R0' + ΔR0') × I' VC = (R0' - ΔR0') × I' It becomes as follows. Expressing the relationship with the potential difference across each strain gauge using the change in strain gauge resistance results in the following equations. (VC / VB) = (R0' - ΔR0') / (R0' + ΔR0') From the above equation, the rate of change of the strain gauge resistance is calculated by the following equation. (ΔR0’ / R0’)=(VC-VB) / (VC+VB) From the above relational expression, the calculation formula for the radius of curvature rn’ of the neutral plane N is rn’=(kd / 2)×(R0’ / ΔR0’) as follows.

[0094] Referring to FIG. 12, let r0 to r3 be the radii of curvature obtained from the detection data of the outer peripheral sensors (GA, GD) at the positions of the strain gauges G0 to Gn (in FIG. 12, n = 0 to 3), and let r0’ to r3’ be the radii of curvature obtained from the detection data of the inner peripheral sensors (GB, GC) at the positions of the strain gauges G0 to Gn (in FIG. 12, n = 0 to 3). At this time, since the arcs between the surface coordinates Pn - surface coordinates Pn’ and the arcs between the surface coordinates Pn’ - surface coordinates Pn + 1 are equal to the array interval L / 2 of the gauge elements (see FIG. 1), the bending angles θn and θn’ are θn = L / 2rn and θn’ = L / 2rn’ (n = 0 to 3). Therefore, the surface coordinates Pn and Pn’ can be calculated from the radii of curvature rn and rn’ and the bending angles θn and θn’.

[0095] The host controller 38 can obtain the surface coordinate P0 (= (0, 0)) of the starting point (origin) as the position of the outer peripheral sensors (GA, GD) of the strain gauge G0 from the radius of curvature r0. Next, the host controller 38 can obtain the surface coordinate P0' as the position of the inner peripheral sensors (GB, GC) of the strain gauge G0 from the radius of curvature r0 and the bending angle θ0. Next, the host controller 38 obtains the surface coordinate P1 as the position of the outer peripheral sensors (GA, GD) of the next strain gauge G1 based on the radius of curvature r0’ and the bending angle θ0’ calculated based on the result measured by the inner peripheral sensors (GB, GC) of the strain gauge G0. By sequentially performing such calculations, the host controller 38 can obtain the positions of the respective strain gauges G0 - G3 (the surface coordinates P0’, P1, P1’, P2, P2’, P3, P3’ when viewed horizontally with the surface coordinate P0 as the origin).

[0096] As described above, the intervals (distances) between P0 and P0', between P'0 and P1, etc. are L / 2. Here, L is the arrangement interval of the gauge elements G0 to Gn of the first strain gauge CDA of the first strain gauge, the gauge elements G0 to Gn of the second strain gauge CDB of the second strain gauge, the gauge elements G0 to Gn of the third strain gauge CDC of the third strain gauge, and the gauge elements G0 to Gn of the fourth strain gauge CDD of the fourth strain gauge. L / 2 is the amount of deviation in the length direction X of the substrate 11 (44, 22) between the first strain gauge elements G0 to Gn of the first strain gauge CDA and the second strain gauge elements G0 to Gn of the second strain gauge CDB in a plan view, or the amount of deviation in the length direction X of the substrate 11 (44, 22) between the third strain gauge elements G0 to Gn of the third strain gauge CDC and the fourth strain gauge elements G0 to Gn of the fourth strain gauge CDD in a plan view. That is, the strain gauge sensor device 10 can be regarded as a strain gauge sensor device in which the gauge elements are arranged in a row along the longitudinal direction X at an interval of L / 2 in a plan view seen from a direction perpendicular to the surface of the substrate 11. Thus, the strain gauge sensor device 10 in which the arrangement interval of the gauge elements is made narrower than the arrangement interval L between adjacent gauge elements can accurately identify the shape of the surface 50a of the subject 50, which is the object to be measured.

[0097] As described above, the strain gauge sensor device 10 can detect the curved surface form of the entire surface 50a of the subject 50 by sequentially calculating the radii of curvature at a plurality of locations on the surface 50a of the subject 50.

[0098] Next, a modification example regarding the power supply potential applied to the sensor patterns CDA, CDB, CDC, and CDD including strain gauges will be described.

[0099] When the strain gauges GB and GC of the strain gauge sensor device 10 and the strain gauges GA and GD are formed of the same material and have the same resistance value, the strain amounts (ε1) of the outer strain gauges GA and GD far from the neutral plane N are larger (ε1 > ε2) than the strain amounts (ε2) of the inner strain gauges GB and GC close to the neutral plane N. Therefore, the power supply voltage applied to the outer strain gauges GA and GD may be made smaller than the power supply voltage applied to the inner strain gauges GB and GC.

[0100] That is, in the second strain gauge CDB and the third strain gauge CDC, one corresponding second strain gauge element GB and one corresponding third strain gauge element GC are connected in series so that they are connected in series, one end of which is connected to a first reference potential (for example, ground potential: 0V), and the other end is connected to a second reference potential higher than the first reference potential (for example, power supply potential: +nV). Similarly, in the first strain gauge CDA and the fourth strain gauge CDD, one corresponding first strain gauge element GA and one corresponding fourth strain gauge element GD are connected in series so that they are connected in series, one end of which is connected to the first reference potential (for example, ground potential: 0V), and the other end is connected to a third reference potential higher than the first reference potential and lower than the second reference potential (for example, power supply potential: +mV, +nV > +mV > 0V).

[0101] Alternatively, the drive voltage value (DV1) between one end and the other end of one corresponding second strain gauge element GB and one corresponding third strain gauge element GC connected in series is made larger (DV1 > DV2) than the drive voltage value (DV2) between one end and the other end of one corresponding first strain gauge element GA and one corresponding fourth strain gauge element GD connected in series. Thereby, the curved shape of the surface of the measurement object can be accurately detected by the strain gauge sensor device 10 which is one detection device, and the power consumption of the strain gauge sensor device 10 can be reduced.

[0102] Note that although the embodiments of the present disclosure have been described, these embodiments are presented as examples and are not intended to limit the scope of the disclosure. The novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the present disclosure. The embodiments and their modifications are included in the scope and gist of the present disclosure, and are included in the present disclosure described in the claims and the equivalent scope thereof.

[0103] Based on each configuration described above as an embodiment of the present disclosure, all configurations that can be appropriately designed and modified by those skilled in the art also belong to the scope of the present disclosure as long as they include the gist of the present disclosure.

[0104] For example, the number of layers of the sensor pattern in the strain gauge sensor device, that is, the number of layers of the strain gauges, is not limited to 4 layers (the deviation amount is (1 / 2)L), but can also be 6 layers (in this case, the deviation amount can be (1 / 3)L), 8 layers (in this case, the deviation amount can be (1 / 4)L), 10 layers (in this case, the deviation amount can be (1 / 5)L), or more. The number of arranged strain gauges in the sensor pattern of the sensor sheet is not limited to the above-described embodiment and can be arbitrarily selected. The constituent materials, dimensions, and shapes of the sensor sheet can be appropriately changed without being limited to the above-described embodiment. The connection line connecting the power line and the ground line is not limited to the plated-through hole and may be composed of wiring within the selector SEL.

Description of Reference Numerals

[0105] 10: Strain gauge sensor device, 11: Substrate, 22: Sheet base material, 40: Drive circuit (detection circuit), 44: Base substrate, G0~Gn, GA, GB, GC, GD: Strain gauges (strain gauge elements), VL: Power line, GNL: Ground line, Sa: First signal line, Sb: Second signal line, SEL: Selector, CDA: First sensor pattern (first strain gauge), CDB: Second sensor pattern (second strain gauge), CDC: Third sensor pattern (third strain gauge), CDD: Fourth sensor pattern (fourth strain gauge), 101, 102, 103, 104: Sheet substrates.

Claims

1. A strip-shaped flexible substrate, a first strain gauge provided on the substrate and including a plurality of first strain gauge elements arranged in a row at a predetermined interval in the length direction of the substrate, a second strain gauge provided on the substrate and including a plurality of second strain gauge elements arranged in a row at a predetermined interval in the length direction of the substrate, a third strain gauge provided on the substrate and including a plurality of third strain gauge elements arranged in a row at a predetermined interval in the length direction of the substrate, a fourth strain gauge provided on the substrate and including a plurality of fourth strain gauge elements arranged in a row at a predetermined interval in the length direction of the substrate, a detection circuit connected to each of the first to fourth strain gauge elements, and each of the first to fourth strain gauges is disposed on the substrate via an insulating layer such that the extending direction of the first to fourth strain gauges is along the length direction of the substrate, the first to fourth strain gauges are laminated in the thickness direction of the substrate in this order such that the extending directions of the first to fourth strain gauges are in the same direction, the second strain gauge element and the third strain gauge element are symmetrically arranged from the central position in the thickness direction of the substrate and overlap in plan view, the first strain gauge element and the fourth strain gauge element are symmetrically arranged from the central position in the thickness direction of the substrate and overlap in plan view, in plan view, the first strain gauge element and the second strain gauge element are displaced in the length direction of the substrate, in plan view, the third strain gauge element and the fourth strain gauge element are displaced in the length direction of the substrate, a detection device.

2. In the detection device according to Claim 1, each of the first to fourth strain gauge elements has a plurality of corresponding strain gauge elements arranged at equal intervals in the length direction of the substrate, the displacement amount between the first strain gauge element and the second strain gauge element in plan view is set to 1 / 2 of the arrangement interval of adjacent strain gauge elements, a detection device in which the displacement amount between the third strain gauge element and the fourth strain gauge element in plan view is set to 1 / 2 of the arrangement interval of adjacent strain gauge elements.

3. In the detection device according to Claim 1, the first strain gauge is disposed on a first sensor substrate, the second strain gauge is disposed on a second sensor substrate, The third strain gauge is disposed on a third sensor substrate, The fourth strain gauge is disposed on a fourth sensor substrate, The detection device, wherein the second sensor substrate and the third sensor substrate are displaced in the length direction of the substrate with respect to the first sensor substrate and the fourth sensor substrate.

4. In the detection device according to claim 1, In the second strain gauge and the third strain gauge, one corresponding second strain gauge element and one corresponding third strain gauge element are connected in series, one end thereof is connected to a first reference potential, and the other end thereof is connected to a second reference potential higher than the first reference potential. In the first strain gauge and the fourth strain gauge, one corresponding first strain gauge element and one corresponding fourth strain gauge element are connected in series, one end thereof is connected to the first reference potential, and the other end thereof is connected to the second reference potential.

5. In the detection device according to claim 1, In a state without strain, the resistance value of the second strain gauge element and the resistance value of the third strain gauge element are the same, and the resistance value of the first strain gauge element and the resistance value of the fourth strain gauge element are the same.

6. In the detection device according to claim 5, In a state with strain, the resistance value of the second strain gauge element and the resistance value of the third strain gauge element are different, and the resistance value of the first strain gauge element and the resistance value of the fourth strain gauge element are different.

7. In the detection device according to claim 6, The detection circuit Obtains a first radius of curvature of the substrate based on the resistance value of the second strain gauge element and the resistance value of the third strain gauge element, Obtains a second radius of curvature of the substrate based on the resistance value of the first strain gauge element and the resistance value of the fourth strain gauge element, The detection device that specifies the shape of an object based on the first radius of curvature and the second radius of curvature.

Images