WO2020013046A1

WO2020013046A1 - Strain gauge, sensor module and bearing mechanism

Info

Publication number: WO2020013046A1
Application number: PCT/JP2019/026450
Authority: WO
Inventors: 英司美齊津; 重之足立; 寿昭浅川; 厚北村
Original assignee: ミネベアミツミ株式会社
Priority date: 2018-07-12
Filing date: 2019-07-03
Publication date: 2020-01-16
Also published as: JP2020008527A; JP2023157950A

Abstract

This strain gauge comprises a flexible base material and a plurality of resistor parts which are linearly formed on one side of the base material. The resistor parts intersect with each other on a same plane and are electrically connected to each other.

Description

Strain gauge, sensor module, bearing mechanism

The present invention relates to a strain gauge, a sensor module, and a bearing mechanism.

ひずみ Strain gauges that are attached to an object to be measured and detect strain of the object to be measured are known. The strain gauge includes a resistor for detecting strain, and the resistor is formed on a base made of, for example, an insulating resin.

It is also possible to stack a plurality of strain gauges so that their grid directions cross each other and detect strain in a plurality of directions (for example, see Patent Document 1).

JP 2016-31326 A

However, when a plurality of strain gauges are stacked such that their grid directions cross each other, a measurement error has occurred due to a displacement or the like during stacking.

The present invention has been made in view of the above points, and has as its object to provide a strain gauge that can accurately detect strains in a plurality of directions.

The strain gauge has a flexible base material and a plurality of resistance portions formed linearly on one side of the base material, and each of the resistance portions intersects on the same plane. Are electrically connected to each other.

According to the disclosed technique, it is possible to provide a strain gauge that can accurately detect strain in a plurality of directions.

FIG. 2 is a plan view illustrating a strain gauge according to the first embodiment. It is a sectional view (the 1) which illustrates the strain gauge concerning a 1st embodiment. FIG. 2 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. FIG. 9 is a schematic view illustrating a sensor module according to a second embodiment. FIG. 9 is a schematic view illustrating a method for using the sensor module according to the second embodiment. It is a top view which illustrates the strain gauge concerning a 3rd embodiment. FIG. 14 is a schematic view illustrating a sensor module according to a fourth embodiment. It is a perspective view which illustrates the bearing mechanism concerning 5th Embodiment. It is sectional drawing which illustrates the bearing mechanism which concerns on 5th Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<First Embodiment>
FIG. 1 is a plan view illustrating a strain gauge according to the first embodiment. FIG. 2 is a cross-sectional view illustrating the strain gauge according to the first embodiment, and shows a cross section taken along line AA in FIG. Referring to FIGS. 1 and 2, the strain gauge 1 has a base material 10, a resistor 30 (resistors 31 and 32), and

terminals

41, 42, 43 and 44.

In the present embodiment, for the sake of convenience, in the strain gauge 1, the side of the substrate 10 where the resistor 30 is provided is on the upper side or one side, and the side where the resistor 30 is not provided is the lower side or the other side. Side. In addition, the surface of each part on which the resistor 30 is provided is defined as one surface or upper surface, and the surface on which the resistor 30 is not provided is defined as the other surface or lower surface. However, the strain gauge 1 can be used upside down, or can be arranged at any angle. The plan view refers to viewing the target from the normal direction of the upper surface 10a of the base material 10, and the planar shape refers to the shape of the target viewed from the normal direction of the upper surface 10a of the base material 10. And

The base material 10 is an insulating member serving as a base layer for forming the resistor 30 and the like, and has flexibility. The thickness of the base material 10 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness can be about 5 μm to 500 μm. In particular, it is preferable that the thickness of the base material 10 be 5 μm to 200 μm, since the strain sensitivity error of the resistor 30 can be reduced.

The substrate 10 is made of, for example, PI (polyimide) resin, epoxy resin, PEEK (polyetheretherketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, polyolefin resin, and the like. From an insulating resin film. Note that a film refers to a member having a thickness of about 500 μm or less and having flexibility.

Here, “formed from an insulating resin film” does not prevent the base material 10 from containing fillers, impurities, and the like in the insulating resin film. The substrate 10 may be formed from, for example, an insulating resin film containing a filler such as silica or alumina.

However, when the base material 10 does not need to have flexibility, the base material 10 is made of SiO ₂ , ZrO ₂ (including YSZ), Si, Si ₂ N ₃ , and Al ₂ O ₃ (including sapphire). , ZnO, and perovskite ceramics (CaTiO ₃ , BaTiO ₃ ).

The resistor 30 is a thin film formed on the base material 10 in a predetermined pattern, and is a sensing part that undergoes a strain and undergoes a resistance change. The resistor 30 may be formed directly on the upper surface 10a of the substrate 10 or may be formed on the upper surface 10a of the substrate 10 via another layer.

The resistor 30 includes the

resistance portions

31 and 32. That is, the resistor 30 is a general term for the

resistor portions

31 and 32, and is referred to as the resistor 30 when it is not necessary to particularly distinguish the

resistor portions

31 and 32. In FIG. 1, for convenience, the

resistance portions

31 and 32 are shown in a satin pattern.

The resistance portion 31 is a thin film formed on the upper surface 10a of the base material 10 in a straight line with the longitudinal direction directed in the X direction. The resistance part 32 is a thin film formed linearly with the longitudinal direction directed in the Y direction. The resistance part 31 and the resistance part 32 are electrically connected to each other at right angles on the same plane. The resistance part 31 and the resistance part 32 can be patterned so as to intersect at a substantially central part in each longitudinal direction, for example.

The resistor 30 can be formed of, for example, a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 30 can be formed from a material containing at least one of Cr and Ni. As a material containing Cr, for example, a Cr mixed-phase film is given. As a material containing Ni, for example, Cu—Ni (copper nickel) is given. As a material containing both Cr and Ni, for example, Ni—Cr (nickel chrome) can be mentioned.

Here, the Cr mixed phase film is a film in which Cr, CrN, Cr ₂ N and the like are mixed. The Cr mixed phase film may contain unavoidable impurities such as chromium oxide.

The thickness of the resistor 30 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness can be about 0.05 μm to 2 μm. In particular, it is preferable that the thickness of the resistor 30 be 0.1 μm or more, since the crystallinity of the crystal constituting the resistor 30 (for example, the crystallinity of α-Cr) is improved. Further, it is more preferable that the thickness of the resistor 30 be 1 μm or less, since cracks in the film and warpage from the substrate 10 due to internal stress of the film constituting the resistor 30 can be reduced. The width of the resistor 30 is not particularly limited and can be appropriately selected depending on the purpose. For example, the width can be about 0.1 μm to 1000 μm (1 mm).

For example, when the resistor 30 is a Cr mixed phase film, the stability of the gauge characteristics can be improved by using α-Cr (alpha chromium), which is a stable crystal phase, as a main component. Further, since the resistor 30 contains α-Cr as a main component, the gauge factor of the strain gauge 1 is 10 or more, and the gauge factor temperature coefficient TCS and the resistance temperature coefficient TCR are within the range of −1000 ppm / ° C. to +1000 ppm / ° C. It can be. Here, the main component means that the target substance occupies 50% by mass or more of all the substances constituting the resistor. From the viewpoint of improving the gauge characteristics, the resistor 30 contains α-Cr at 80% by weight. It is preferable to include the above. Note that α-Cr is Cr having a bcc structure (body-centered cubic lattice structure).

The terminal portion 41 extends from one end of the resistor portion 31 and is formed in a substantially circular shape with a wider width than the resistor portion 31 in plan view. The terminal portion 43 extends from the other end of the resistor portion 31 and is formed in a substantially circular shape with a wider width than the resistor portion 31 in a plan view. The

terminal portions

41 and 43 are a pair of electrodes for outputting a change in the resistance value of the resistance portion 31 caused by the strain to the outside, and for example, a flexible substrate for external connection, a lead wire, or the like is joined. The upper surfaces of the

terminal portions

41 and 43 may be covered with a metal having better solderability than the

terminal portions

41 and 43. In addition, although the resistance part 31 and the

terminal parts

41 and 43 are represented by different reference numerals for convenience, they can be integrally formed of the same material in the same step. The planar shape of the

terminal portions

41 and 43 is not limited to a circular shape, and may be a rectangular shape or the like.

The terminal portion 42 extends from one end of the resistor portion 32, and is formed in a substantially circular shape with a wider width than the resistor portion 32 in a plan view. The terminal portion 44 extends from the other end of the resistor portion 32, and is formed in a substantially circular shape with a wider width than the resistor portion 32 in a plan view. The

terminal portions

42 and 44 are a pair of electrodes for outputting a change in the resistance value of the resistance portion 32 caused by the strain to the outside, and for example, a flexible board for external connection, a lead wire, or the like is joined. The upper surfaces of the

terminal portions

42 and 44 may be covered with a metal having better solderability than the

terminal portions

42 and 44. In addition, although the resistance part 32 and the

terminal parts

42 and 44 are represented by different reference numerals for convenience, they can be integrally formed of the same material in the same step. The planar shape of the

terminal portions

42 and 44 is not limited to a circular shape, but may be a rectangular shape or the like.

カバー A cover layer 60 (insulating resin layer) may be provided on the upper surface 10a of the base material 10 so as to cover the resistor 30 and expose the terminal portions 41 to 44. The provision of the cover layer 60 can prevent the resistor 30 from being mechanically damaged. Further, by providing the cover layer 60, the resistor 30 can be protected from moisture and the like. Note that the cover layer 60 may be provided so as to cover the entire portion except for the terminal portions 41 to 44.

The cover layer 60 can be formed from, for example, an insulating resin such as a PI resin, an epoxy resin, a PEEK resin, a PEN resin, a PET resin, a PPS resin, and a composite resin (for example, a silicone resin or a polyolefin resin). The cover layer 60 may contain a filler or a pigment. The thickness of the cover layer 60 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness can be about 2 μm to 30 μm.

において In the strain gauge 1, the resistance section 31 can detect the strain in the X direction as a change in the resistance value, and output the change from the

terminal sections

41 and 43, which are a pair of electrodes. Further, the resistance section 32 can detect the strain in the Y direction as a change in the resistance value and output the change from the

terminal sections

42 and 44 which are a pair of electrodes.

However, it is an example that the resistance part 31 and the resistance part 32 are orthogonal to each other on the same plane as shown in FIG. 1, and the resistance part 31 and the resistance part 32 are formed linearly and are on the same plane. It is only necessary to cross at. In this case, the resistance part 31 and the resistance part 32 can detect the respective strains in the longitudinal direction. For example, the resistance part 31 can be formed linearly with the longitudinal direction directed in the X direction, and the resistance part 32 can be formed linearly with the longitudinal direction inclined at 45 degrees to the X direction.

ひずみ In addition, based on the strain detected by the resistance part 31 and the strain detected by the resistance part 32, the strain in the direction different from the longitudinal direction of the

resistance parts

31 and 32 can be calculated.

In order to manufacture the strain gauge 1, first, the base material 10 is prepared, and the planar resistor 30 and the terminal portions 41 to 44 shown in FIG. 1 are formed on the upper surface 10a of the base material 10. The materials and thicknesses of the resistor 30 and the terminals 41 to 44 are as described above. The resistor 30 and the terminal portions 41 to 44 can be integrally formed of the same material.

The resistor 30 and the terminal portions 41 to 44 can be formed by, for example, forming a film by a magnetron sputtering method using a material capable of forming the resistor 30 and the terminal portions 41 to 44 as a target, and patterning the film by photolithography. The resistor 30 and the terminal portions 41 to 44 may be formed by a reactive sputtering method, an evaporation method, an arc ion plating method, a pulse laser deposition method, or the like instead of the magnetron sputtering method.

From the viewpoint of stabilizing the gauge characteristics, before forming the resistor 30 and the terminal portions 41 to 44, a film thickness of about 1 nm to 100 nm is formed on the upper surface 10a of the base material 10 by, for example, a conventional sputtering method. It is preferable to form the functional layer by vacuum deposition. After forming the resistor 30 and the terminals 41 to 44 on the entire upper surface of the functional layer, the functional layer is patterned by photolithography together with the resistor 30 and the terminals 41 to 44 into the planar shape shown in FIG.

において In the present application, the functional layer refers to a layer having a function of promoting crystal growth of at least the upper layer of the resistor 30. The functional layer preferably further has a function of preventing the resistor 30 from being oxidized by oxygen or moisture contained in the substrate 10 and a function of improving the adhesion between the substrate 10 and the resistor 30. The functional layer may further have another function.

Since the insulating resin film constituting the base material 10 contains oxygen and moisture, especially when the resistor 30 contains Cr, Cr forms a self-oxidized film, so that the functional layer has a function of preventing oxidation of the resistor 30. Providing is effective.

The material of the functional layer is not particularly limited as long as it has a function of promoting the crystal growth of the resistor 30 as the upper layer, and can be appropriately selected depending on the purpose. For example, Cr (chromium), Ti ( Titanium), V (vanadium), Nb (niobium), Ta (tantalum), Ni (nickel), Y (yttrium), Zr (zirconium), Hf (hafnium), Si (silicon), C (carbon), Zn ( Zinc), Cu (copper), Bi (bismuth), Fe (iron), Mo (molybdenum), W (tungsten), Ru (ruthenium), Rh (rhodium), Re (rhenium), Os (osmium), Ir ( Selected from the group consisting of iridium), Pt (platinum), Pd (palladium), Ag (silver), Au (gold), Co (cobalt), Mn (manganese), and Al (aluminum) One or more metals, or metal alloys of this group, or a compound of any one of metals of this group and the like.

Examples of the above alloy include FeCr, TiAl, FeNi, NiCr, CrCu and the like. Examples of the above compound include TiN, TaN, Si ₃ N ₄ , TiO ₂ , Ta ₂ O ₅ , and SiO ₂ .

The functional layer can be formed, for example, by a conventional sputtering method using a material capable of forming the functional layer as a target and introducing an Ar (argon) gas into the chamber. By using the conventional sputtering method, the functional layer is formed while the upper surface 10a of the substrate 10 is etched with Ar, so that the effect of improving the adhesion can be obtained by minimizing the amount of the functional layer formed.

However, this is an example of a method for forming a functional layer, and the functional layer may be formed by another method. For example, before forming the functional layer, the upper surface 10a of the base material 10 is activated by plasma treatment using Ar or the like to obtain an adhesion improving effect, and thereafter, the functional layer is formed into a vacuum by a magnetron sputtering method. May be used.

組合せ The combination of the material of the functional layer and the material of the resistor 30 and the terminals 41 to 44 is not particularly limited and can be appropriately selected depending on the purpose. For example, it is possible to form a Cr mixed phase film containing α-Cr (alpha chromium) as a main component as the resistor 30 and the terminal portions 41 to 44 using Ti as the functional layer.

In this case, for example, the resistor 30 and the terminal portions 41 to 44 can be formed by a magnetron sputtering method using a raw material capable of forming a Cr mixed phase film as a target and introducing an Ar gas into the chamber. Alternatively, the resistor 30 and the terminal portions 41 to 44 may be formed by a reactive sputtering method by introducing an appropriate amount of nitrogen gas together with Ar gas into a chamber using pure Cr as a target.

According to these methods, the growth surface of the Cr mixed phase film is defined by the functional layer made of Ti, and a Cr mixed phase film having α-Cr as a main component, which has a stable crystal structure, can be formed. Further, the gauge characteristics are improved by diffusing Ti constituting the functional layer into the Cr mixed phase film. For example, the gauge factor of the strain gauge 1 can be 10 or more, and the gauge factor temperature coefficient TCS and the resistance temperature coefficient TCR can be in the range of −1000 ppm / ° C. to +1000 ppm / ° C. When the functional layer is formed of Ti, the Cr mixed phase film may include Ti or TiN (titanium nitride).

When the resistor 30 is a Cr mixed phase film, the functional layer made of Ti has a function of promoting the crystal growth of the resistor 30 and a function of preventing the resistor 30 from being oxidized by oxygen or moisture contained in the base material 10. , And all the functions of improving the adhesion between the substrate 10 and the resistor 30. The same applies when Ta, Si, Al, or Fe is used instead of Ti as the functional layer.

As described above, by providing the functional layer below the resistor 30, the crystal growth of the resistor 30 can be promoted, and the resistor 30 having a stable crystal phase can be manufactured. As a result, in the strain gauge 1, the stability of the gauge characteristics can be improved. In addition, since the material constituting the functional layer diffuses into the resistor 30, the gauge characteristics of the strain gauge 1 can be improved.

After forming the resistor 30 and the terminal portions 41 to 44, if necessary, a cover layer 60 that covers the resistor 30 and exposes the terminal portions 41 to 44 is provided on the upper surface 10a of the base material 10, so that the strain gauge 1 Is completed. The cover layer 60 is formed, for example, by laminating a thermosetting insulating resin film in a semi-cured state on the upper surface 10a of the base material 10 so as to cover the resistor 30 and expose the terminal portions 41 to 44, and then cure by heating. It can be made by making. The cover layer 60 is formed by applying a liquid or paste-like thermosetting insulating resin to the upper surface 10a of the base material 10 so as to cover the resistor 30 and expose the terminal portions 41 to 44, and then heat to cure the resin. It may be produced.

In the case where a functional layer is provided on the upper surface 10a of the base material 10 as a base layer for the resistor 30 and the terminal portions 41 to 44, the strain gauge 1 has a cross-sectional shape shown in FIG. The layer indicated by reference numeral 20 is a functional layer. The plane shape of the strain gauge 1 when the functional layer 20 is provided is the same as that in FIG.

As described above, in the strain gauge 1, the

resistance portions

31 and 32 are each formed in a straight line, intersect on the same plane, and are mutually conductive. Thus, by sequentially connecting the

resistance units

31 and 32 to the bridge circuit, it is possible to detect the longitudinal strain of each of the

resistance units

31 and 32 based on the change in the resistance value of the

resistance units

31 and 32. . That is, the strain gauge 1 can realize a multiaxial gauge capable of detecting strain in two directions.

Conventionally, when detecting strain in two directions, for example, two strain gauges are manufactured and both are stacked so that their grid directions cross each other. The measurement error occurred due to the difference in the position of the strain gauges in the stacking direction. On the other hand, in the strain gauge 1, since the

resistance portions

31 and 32 are simultaneously patterned on the same surface, the manufacturing process can be simplified, and a measurement error due to a displacement or the like can be suppressed.

In addition, since the

resistance portions

31 and 32 are patterned on the same surface in the strain gauge 1, the size can be reduced as compared with a structure in which a plurality of strain gauges are attached. As a result, it can be easily attached to a desired measurement position.

Further, in the strain gauge 1, particularly when the resistor 30 is formed of a Cr mixed phase film, the sensitivity of the resistance value to the strain is greater than when the resistor 30 is formed of Cu—Ni or Ni—Cr. (The amount of change in the resistance value of the resistor 30 for the same strain) is greatly improved. When the resistor 30 is formed of the Cr mixed phase film, the sensitivity of the resistance value to the strain is about 5 to 10 times that in the case where the resistor 30 is formed of Cu—Ni or Ni—Cr. . Therefore, by forming the resistor 30 from a Cr mixed-phase film, it is possible to accurately detect distortion.

<Second embodiment>
In the second embodiment, an example of a sensor module in which a selection circuit is mounted on the strain gauge according to the first embodiment will be described. Note that in the second embodiment, the description of the same components as those in the above-described embodiment may be omitted.

FIG. 4 is a schematic view illustrating the sensor module according to the second embodiment. In FIG. 4, the strain gauge 1 (see FIGS. 1 and 2) is simplified, and only the terminals 41 to 44 are shown.

参照 Referring to FIG. 4, the sensor module 5 includes a strain gauge 1 and a selection circuit 2.

The selection circuit 2 includes, for example, switches SW ₁ and SW ₂ , input terminals I ₁ to I ₄ , output terminals O ₁ and O ₂ , a control terminal CNT, and power supply terminals VDD and VSS (positive terminal and negative terminal). An IC having the following. The power supply terminals VDD and VSS are supplied with power of a predetermined voltage from outside the sensor module 5. The control terminal CNT and the output terminals O ₁ and O ₂ can be electrically connected to the outside of the sensor module 5. The selection circuit 2 can be mounted on the upper surface 10a side or the lower surface 10b side of the base material 10 of the strain gauge 1, for example.

In the selection circuit 2, the input terminals I ₁ and I ₃ are connected to

terminal portions

41 and 43 which are a pair of electrodes of the resistance portion 31. The input terminals I ₂ and I ₄ are connected to

terminal portions

42 and 44 which are a pair of electrodes of the resistance portion 32.

Switches SW ₁ and SW ₂ is a switch that is switched in conjunction in accordance with the H / L signal externally input to the control terminal CNT.

For example, when an H signal is externally input to the control terminal CNT, SW ₁ connects the input terminal I ₁ and the output terminal O _1, and SW ₂ connects the input terminal I ₃ and the output terminal O ₂ ( FIG. 4). In this case, the output terminals O ₁ and O ₂ are connected to the

terminal portions

41 and 43 which are a pair of electrodes of the resistance portion 31, and the resistance value of the resistance portion 31 can be measured via the output terminals O ₁ and O _2. Become.

On the other hand, when the L signal is input from the outside to the control terminal CNT, SW ₁ is connected to an input terminal _{I 2} and the output terminal _{O 1,} SW ₂ connects the input terminal _{I 4} and output terminal _{O 2.} In this case, the output terminals O ₁ and O ₂ are connected to the

terminals

42 and 44 which are a pair of electrodes of the resistor 32, and the resistance of the resistor 32 can be measured via the output terminals O ₁ and O _2. Become.

FIG. 5 is a schematic view illustrating a method for using the sensor module according to the second embodiment. Referring to FIG. 5, the sensor module 5 can be connected to a measurement unit 7 arranged outside the sensor module 5.

The measuring unit 7 includes a bridge circuit 71, an analog front end unit 72, and a control unit 73.

The bridge circuit 71 includes fixed resistances R ₁ , R ₂ , and R ₃ on three sides, and the other side is connected to output terminals O ₁ and O ₂ of the selection circuit 2 of the sensor module 5. A DC voltage V is applied between a pair of diagonal points of the bridge circuit 71. With this configuration, an analog voltage corresponding to the distortion of the

resistor

31 or 32 selected by the selection circuit 2 is output between the other pair of diagonal points of the bridge circuit 71. The voltage output from the bridge circuit 71 is input to the analog front end unit 72.

In this case, the connection between the strain gauge 1 and the bridge circuit 71 is a one-gauge two-wire system, but is not limited to this.

The analog front-end unit 72 includes, for example, an amplifier, an analog / digital conversion circuit (A / D conversion circuit), an external communication function (for example, a serial communication function such as I ² C). The analog front end unit 72 may include a temperature compensation circuit. The analog front end unit 72 may be formed as an IC, or may be formed of individual components.

In the analog front-end unit 72, the voltage output from the bridge circuit 71 is amplified by an amplifier, converted to a digital signal by an A / D conversion circuit, and output. When the analog front end unit 72 includes a temperature compensation circuit, a temperature-compensated digital signal is output.

Control unit 73 receives the H signal or L signal to the control terminal CNT of the selection circuit 2 of the sensor module 5, it is possible to switch the switch SW ₁ and SW _2. The control unit 73 can be configured to include, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a main memory, and the like.

In this case, the various functions of the control unit 73 can be realized by reading a program recorded in a ROM or the like into the main memory and executing the program by the CPU. However, part or all of the control unit 73 may be realized only by hardware. Further, the control unit 73 may be physically constituted by a plurality of devices or the like.

Thus, the H signal or the L signal is input from the outside to the control terminal CNT of the selection circuit 2 of the sensor module 5, it is possible to switch the switch SW ₁ and SW ₂ of the selection circuit 2. Thereby, the resistance value of the resistance part 31 and the resistance value of the resistance part 32 of the strain gauge 1 can be selectively measured. That is, the strain in the X direction and the strain in the Y direction can be selectively measured.

<Third embodiment>
In the third embodiment, an example of a strain gauge in which the direction of strain detection is increased compared to the first embodiment will be described. In the third embodiment, the description of the same components as those in the above-described embodiment may be omitted.

FIG. 6 is a plan view illustrating a strain gauge according to the third embodiment. The sectional shape of the strain gauge according to the third embodiment is the same as that of FIG. Referring to FIG. 6, strain gauge 1A is different from strain gauge 1 (see FIGS. 1 and 2) in that the number of pairs of a resistor and a pair of terminals is increased from two to four. That is, the strain gauge 1A is a multiaxial gauge capable of detecting strain in four directions.

において In the strain gauge 1A, the resistor 30A is a thin film formed in a predetermined pattern on the base material 10, and is a sensing portion that undergoes a strain and undergoes a resistance change. The resistor 30A may be formed directly on the upper surface 10a of the substrate 10, or may be formed on the upper surface 10a of the substrate 10 via another layer. The material, thickness, manufacturing method, and the like of the resistor 30A can be the same as those of the resistor 30.

The resistor 30A includes the

resistor portions

31, 32, 33, and. That is, the resistor 30A is a general term for the

resistors

31, 32, 33, and 34, and is referred to as the resistor 30A unless it is necessary to particularly distinguish the

resistors

31, 32, 33, and 34. In FIG. 6, 31, 32, 33, and 34 are shown in a satin pattern for convenience.

The resistance portion 31 is a thin film formed on the upper surface 10a of the base material 10 in a straight line with the longitudinal direction directed in the X direction. The resistance part 32 is a thin film formed linearly with the longitudinal direction directed in the Y direction. Resistor 33, the upper surface 10a of the substrate 10, the longitudinal angle theta ₁ with the X direction is a thin film formed in a linear shape in a direction to be -45 degrees. Resistor 34, the upper surface 10a of the substrate 10, the longitudinal angle theta ₂ between the X-direction is a thin film formed in a linear shape in a direction to be +45 degrees. Here, the counterclockwise direction is defined as a positive angle.

(4) The

resistance portions

31, 32, 33, and 34 cross each other on the same plane and are electrically connected to each other. The

resistance portions

31, 32, 33, and 34 can be patterned, for example, so as to intersect at a substantially central portion in each longitudinal direction. That is, the

resistance portions

31, 32, 33, and 34 are each formed in a straight line, cross each other on the same plane, and are electrically connected to each other, and the angle between adjacent resistance portions is 45 degrees.

The terminal portion 45 extends from one end of the resistor portion 33 and is formed in a substantially circular shape with a wider width than the resistor portion 33 in a plan view. The terminal portion 47 extends from the other end of the resistor portion 33 and is formed in a substantially circular shape with a wider width than the resistor portion 33 in a plan view. The

terminal portions

45 and 47 are a pair of electrodes for outputting a change in the resistance value of the resistance portion 33 caused by the strain to the outside, and for example, a flexible board or a lead wire for external connection is joined. The upper surfaces of the

terminal portions

45 and 47 may be covered with a metal having better solderability than the

terminal portions

45 and 47. Although the resistor 33 and the

terminals

45 and 47 have different reference numerals for convenience, they can be integrally formed of the same material in the same step. The planar shape of the

terminal portions

45 and 47 is not limited to a circular shape, but may be a rectangular shape or the like.

The terminal portion 46 extends from one end of the resistor portion 34, and is formed in a substantially circular shape with a wider width than the resistor portion 34 in plan view. The terminal portion 48 extends from the other end of the resistor portion 34, and is formed in a substantially circular shape with a wider width than the resistor portion 34 in a plan view. The

terminal portions

46 and 48 are a pair of electrodes for outputting a change in the resistance value of the resistance portion 34 caused by the strain to the outside, and for example, a flexible board or a lead wire for external connection is joined. The upper surfaces of the

terminal portions

46 and 48 may be covered with a metal having better solderability than the

terminal portions

46 and 48. Although the resistor 34 and the

terminals

46 and 48 have different reference numerals for convenience, they can be integrally formed of the same material in the same step. The planar shape of the

terminal portions

46 and 48 is not limited to a circular shape, but may be a rectangular shape or the like.

カバー A cover layer 60 (insulating resin layer) may be provided on the upper surface 10a of the base material 10 so as to cover the resistor 30A and expose the terminal portions 41 to 48. By providing the cover layer 60, it is possible to prevent the resistor 30A from being mechanically damaged. Further, by providing the cover layer 60, the resistor 30A can be protected from moisture and the like. Note that the cover layer 60 may be provided so as to cover the entire portion except for the terminal portions 41 to 48.

In the strain gauge 1A, the resistance section 31 can detect the strain in the X direction as a change in the resistance value and output it from the

terminal sections

41 and 43 that are a pair of electrodes. Further, the resistance section 32 can detect the strain in the Y direction as a change in the resistance value and output the change from the

terminal sections

42 and 44 which are a pair of electrodes. The resistor unit 33 can detect the strain in the direction forming angle theta ₁ with the X direction is -45 ° as a change in resistance value, and outputs from the

terminals

45 and 47 are a pair of electrodes. The resistor 34 may be an angle theta ₂ between the X direction is detected as a change in resistance strain direction the +45 degrees and output from the

terminal unit

46 and 48 is a pair of electrodes.

As described above, in the strain gauge 1A, the

resistance portions

31, 32, 33, and 34 are each formed in a straight line, intersect on the same plane, and are electrically connected to each other, and form an angle between the adjacent resistance portions. Is 45 degrees. Accordingly, by sequentially connecting the

resistance units

31, 32, 33, and 34 to the bridge circuit, the

resistance units

31, 32, 33, and 34 are changed based on the change in the resistance value of the

resistance units

31, 32, 33, and 34. And 34 can be detected in the longitudinal direction. Further, the magnitude and direction of the main strain can be known by calculation based on the detection results of the strains of the

resistance portions

31, 32, 33, and. Other effects are the same as those of the first embodiment.

<Fourth embodiment>
In the fourth embodiment, an example of a sensor module in which a selection circuit is mounted on the strain gauge according to the third embodiment will be described. In the fourth embodiment, the description of the same components as those of the above-described embodiment may be omitted.

FIG. 7 is a schematic view illustrating the sensor module according to the fourth embodiment. In FIG. 7, the strain gauge 1A (see FIG. 6) is simplified, and only the terminals 41 to 48 are shown.

参照 Referring to FIG. 7, the sensor module 5A has a strain gauge 1A and a selection circuit 2A.

Selection circuit 2A, for example, the switch SW ₁ and SW _2, the input terminals _I 1 ~ _{I 8,} and the output terminals _{O 1} and _{O 2,} and control terminals CNT ₁ and CNT _2, the power supply terminals VDD and VSS (positive terminal And a negative electrode terminal). The power supply terminals VDD and VSS are supplied with power of a predetermined voltage from outside the sensor module 5A. The control terminals CNT ₁ and CNT ₂ and the output terminals O ₁ and O ₂ can be electrically connected to the outside of the sensor module 5A. The selection circuit 2A can be mounted, for example, on the upper surface 10a side or the lower surface 10b side of the base material 10 of the strain gauge 1A.

In selecting circuit 2A, the input terminals _{I 1} and _{I 5} are connected to the

terminal portions

41 and 43 are a pair of electrodes of the resistance portion 31. The input terminals I ₂ and I ₆ are connected to

terminal portions

42 and 44 which are a pair of electrodes of the resistance portion 32. Further, the input terminals I ₃ and I ₇ are connected to

terminal portions

45 and 47 which are a pair of electrodes of the resistance portion 33. The input terminals I ₄ and I ₈ are connected to

terminal portions

46 and 48 which are a pair of electrodes of the resistance portion 34.

Switches SW ₃ and SW ₄ are switches for switching in conjunction in accordance with the combination of the H / L signal externally input to the control terminal CNT ₁ and CNT _2.

For example, when an H signal is input to the control terminal CNT ₁ from the outside and an H signal is input to the control terminal CNT ₂ from the outside, SW ₃ connects the input terminal I ₁ to the output terminal O _1, and SW ₄ connects to the input terminal I ₅ and connects the output terminal _{O 2} (the state shown in FIG. 7). In this case, the output terminals O ₁ and O ₂ are connected to the

terminal portions

When an external H signal is input to the control terminal CNT ₁ and an external L signal is input to the control terminal CNT ₂ , SW ₃ connects the input terminal I ₂ to the output terminal O _1, and SW ₄ connects the input terminal I ₆ and connects the output terminal _{O 2.} In this case, the output terminals O ₁ and O ₂ are connected to the

terminals

When an L signal is input to the control terminal CNT ₁ from the outside and an H signal is input to the control terminal CNT ₂ from the outside, SW ₃ connects the input terminal I ₃ to the output terminal O _1, and SW ₄ connects to the input terminal I ₇ and connecting the output terminal _{O 2.} In this case, the output terminals O ₁ and O ₂ are connected to the

terminal portions

45 and 47 which are a pair of electrodes of the resistance portion 33, and the resistance value of the resistance portion 33 can be measured via the output terminals O ₁ and O _2. Become.

When an L signal is externally input to the control terminal CNT ₁ and an L signal is externally input to the control terminal CNT ₂ , SW ₃ connects the input terminal I ₄ to the output terminal O _1, and SW ₄ connects the input terminal I ₈ and connects the output terminal _{O 2.} In this case, the output terminals O ₁ and O ₂ are connected to the

terminal portions

46 and 48 which are a pair of electrodes of the resistance portion 34, and the resistance value of the resistance portion 34 can be measured via the output terminals O ₁ and O _2. Become.

Using the sensor module 5A, except that the control unit 73 controls the control terminals CNT ₁ and CNT ₂ selection circuit 2A, which is the same as the method described with reference to FIG.

Thus, the combination of H / L signal externally input to the control terminal CNT ₁ and CNT ₂ of selecting circuits 2A sensor module 5A, it is possible to switch the switch SW ₃ and SW ₄ of the selection circuit 2A. Thereby, the resistance value of the resistance part 31, the resistance value of the resistance part 32, the resistance value of the resistance part 33, and the resistance value of the resistance part 34 of the strain gauge 1A can be selectively measured. That is, it is possible to selectively measure the strain in the X direction, the strain in the Y direction, and the strain in a direction in which the angle formed with the X direction is ± 45 degrees.

<Fifth Embodiment>
In the fifth embodiment, an example of a bearing mechanism having a strain gauge will be described. Note that, in the fifth embodiment, the description of the same components as those of the already described embodiment may be omitted.

FIG. 8 is a perspective view illustrating a bearing mechanism according to the fifth embodiment. FIG. 9 is a cross-sectional view illustrating a bearing mechanism according to the fifth embodiment.

及び Referring to FIGS. 8 and 9, the bearing mechanism 100 includes a rotating shaft 110 (shaft), a bearing 120 (bearing), and the strain gauge 1. The rotating shaft 110 is rotatably supported by a bearing 120. The strain gauge 1 is attached to a side wall of the bearing 120.

振動 By attaching the strain gauge 1 to the side wall of the bearing 120, vibration of the bearing 120 can be detected. The life of the bearing 120 is greatly affected by vibration in addition to the original rolling fatigue life. By attaching the strain gauge 1 to the bearing 120 and detecting the vibration, the life of the bearing 120 can be predicted based on the result of the vibration detection by the strain gauge 1.

Furthermore, by feeding back the vibration information obtained from the strain gauge 1, it is possible to avoid adverse effects on various products using the bearing 120. In particular, since the strain gauge 1 is a two-axis gauge, a vibration component in a direction perpendicular to the rotation axis 110 and a vibration component in the direction of the rotation axis 110 can be simultaneously detected. As a result, more accurate life prediction of the bearing 120 is possible.

Alternatively, a strain gauge 1A can be used instead of the strain gauge 1. If the bearing mechanism 100 is unbalanced, it tends to vibrate in the direction perpendicular to the rotating shaft 110, and if the alignment is not correct, vibration occurs in the direction of the rotating shaft 110.

Since vibration has a characteristic in the direction of occurrence depending on the type of abnormality, it is preferable to measure the vibration in each of three directions: vertical, horizontal, and axial. By using the strain gauge 1A, it is possible to simultaneously detect vibrations in three directions, so that the ability to isolate vibration sources can be greatly improved.

As described above, in the bearing mechanism 100, by attaching the

strain gauge

1 or 1A to the side wall of the bearing 120 and detecting the vibration of the bearing 120, it is possible to accurately detect the abnormal mode of the vibration generated in the bearing 120. it can.

センサ Note that the

sensor module

5 or 5A may be used instead of the

strain gauge

1 or 1A.

As described above, the preferred embodiments and the like have been described in detail. However, the present invention is not limited to the above-described embodiments and the like, and various modifications may be made to the above-described embodiments and the like without departing from the scope described in the claims. Variations and substitutions can be made.

For example, the bridge circuit 71 may be incorporated in the

sensor module

5 or 5A. Further, the bridge circuit 71 and the analog front end unit 72 may be incorporated in the

sensor module

5 or 5A. In this case, for example, the bridge circuit 71 and the analog front end unit 72 can be integrated into an IC and mounted on the upper surface 10a or the lower surface 10b of the base material 10.

In the multiaxial gauge, the number of resistance portions is not limited to two or four, and may be three or five or more.

This international application claims priority based on Japanese Patent Application No. 2018-132478 filed on Jul. 12, 2018, and incorporates the entire contents of Japanese Patent Application No. 2018-132478 into this international application. .

1, 1A strain gauge, 2, 2A selection circuit, 5, 5A sensor module, 7 measurement section, 10 base, 10a upper base, 10b lower base, 20 functional layer, 30, 30A resistor, 31 ~ 34 ° resistance section, 41 to 48 ° terminal section, 60 ° cover layer, 71 ° bridge circuit, 72 ° analog front end section, 73 ° control section, 100 ° bearing mechanism, 110 ° rotary shaft, 120 ° bearing

Claims

A flexible substrate;
Having a plurality of resistance portions formed linearly on one side of the base material,
A strain gauge in which the resistance portions cross each other on the same plane and are electrically connected to each other.
The strain gauge according to claim 1, wherein the plurality of resistance sections include resistance sections orthogonal to each other.
3. The strain gauge according to claim 1, wherein the plurality of resistance parts include resistance parts having an angle of 45 degrees with each other. 4.
4. The strain gauge according to claim 1, wherein each of the resistance portions is formed of a Cr mixed phase film. 5.
(5) The strain gauge according to (4), wherein each of the resistance portions is mainly composed of alpha chrome.
(6) The strain gauge according to claim 5, wherein each of the resistance parts contains at least 80% by weight of alpha chrome.
7. The strain gauge according to claim 5, wherein each of the resistance portions includes chromium nitride.
The strain gauge according to any one of claims 1 to 7, wherein a functional layer formed of a metal, an alloy, or a compound of a metal is provided below each of the resistance portions.
The strain gauge according to claim 8, wherein the functional layer has a function of promoting crystal growth of each of the resistance portions.
The strain gauge according to any one of claims 1 to 9, wherein a pair of electrodes are formed at both ends of each of the resistance portions.
A strain gauge according to claim 10, and a selection circuit,
The selection circuit,
An input terminal connected to the pair of electrodes of each of the resistance units,
A switch configured to select a pair of the electrodes of any one of the resistance units from a pair of the electrodes of each of the resistance units connected to the input terminal and connect the pair of electrodes to a pair of output terminals. Sensor module.
The sensor module according to claim 11, wherein the selection circuit is mounted on one side or the other side of the base.
The sensor module according to claim 11 or 12, further comprising a bridge circuit in which the pair of output terminals is connected to one side and the other three sides are configured with fixed resistors.
14. The sensor module according to claim 13, further comprising: an analog front end unit that amplifies an analog voltage output from the bridge circuit, converts the voltage into a digital signal, and outputs the digital signal.
A strain gauge according to any one of claims 1 to 10, or a sensor module according to any one of claims 11 to 14,
A rotation axis,
And a bearing that rotatably supports the rotating shaft,
A bearing mechanism for detecting vibration of the bearing by the strain gauge or the sensor module;