Sensor device, force detection device, and robot

A sensor device includes: a base having a recess; a force detecting element which is provided in the recess, and includes at least one piezoelectric element that outputs a signal in accordance with an external force; an adhesive which is provided between the force detecting element and a bottom surface of the recess; at least one electrode provided in the force detecting element; at least one terminal provided in the base; and at least one conductive paste which electrically connects the electrode and the terminal to each other, in which the conductive paste has a part that overlaps the adhesive when viewed from a direction in which the force detecting element and the bottom surface overlap each other, and in which the force detecting element overlaps the bottom surface when viewed from the direction in which the force detecting element and the bottom surface overlap each other.

BACKGROUND

1. Technical Field

The present invention relates to a sensor device, a force detection device, and a robot.

2. Related Art

From the related art, in an industrial robot having an end effector and a robot arm, a force detection device for detecting a force applied to the end effector is used.

As an example of such a force detection device, for example, JP-A-2015-87292 discloses a sensor device including: a base portion having a recess portion; a laminated body having a piezoelectric layer and an electrode provided in the recess portion; a side electrode provided on a side surface of the laminated body; a terminal provided on the base portion; and a connection electrode which connects the terminal and the side electrode. In addition, the connection electrode is formed of Ag paste or the like, and the base portion is formed of Kovar.

In the sensor device disclosed in JP-A-2015-87292, the laminated body is fixed to the base portion as the connection electrode connects the side electrode and the terminal to each other. Therefore, the sensor device has low resistance with respect to mechanical stress, such as vibration. In addition, when connecting the laminated body to the terminal by the connection electrode, there is a concern that the Ag paste which is the base material of the connection electrode drips to a bottom surface of the recess portion before being cured. As a result, there is a concern that a short circuit is generated due to contact of the connection electrode formed of Ag paste with the base portion formed of Kovar. Furthermore, for example, when disposing the laminated body in the recess portion, it is necessary to use a positioning jig or the like to position the laminated body on the inside of the recess portion, and thus, there is a problem that much labor is required such as disposition and detachment of the jig to and from the recess portion when manufacturing the jig.

SUMMARY

A sensor device according to an aspect of the invention includes: a base having a recess; a force detecting element which is provided in the recess, and includes at least one piezoelectric element that outputs a signal in accordance with an external force; an adhesive which is provided between the force detecting element and a bottom surface of the recess, and has insulating properties; at least one electrode provided in the force detecting element; at least one terminal provided in the base; and at least one conductive paste which electrically connects the electrode and the terminal to each other, in which the conductive paste has a part that overlaps the adhesive when viewed from a direction in which the force detecting element and the bottom surface overlap each other, the bottom surface has a part made of metal, and the force detecting element overlaps the part made of the metal on the bottom surface when viewed from the direction in which the force detecting element and the bottom surface overlap each other.

According to the sensor device according to the aspect of the invention, since it is possible to adhere the force detecting element to the bottom surface of the recess by the adhesive, it is possible to enhance stability of the position of the force detecting element in the recess. Therefore, it is possible to reduce deterioration of resistance against mechanical stress, such as vibration. As a result, it is possible to output the signal that corresponds to the external force with high accuracy, and thus, to improve the detection accuracy of the external force.

In addition, for example, it is possible to electrically connect the force detecting element to the circuit (external force detection circuit) which calculates a detection result (electric charge) output from the force detecting element through the electrode, a conductive paste, and a terminal.

In addition, it is possible to reduce or prevent the conductive paste from coming into contact with the bottom surface. Therefore, for example, in a case where the bottom surface is made of a material having conductivity, it is possible to prevent a short circuit due to the contact between the conductive paste and the bottom surface.

In addition, it is possible to enhance mechanical strength, such as brittleness of the bottom surface.

In addition, it is possible to reduce or avoid occurrence of damage, such as cracks, on the bottom surface, for example, due to a load from the force detecting element on the bottom surface.

In addition, it is possible to reduce or prevent a short circuit due to contact between the bottom surface and the force detecting element, for example, even in a case where the bottom surface of the recess and a surface on the base side of the force detecting element have conductivity.

In the sensor device, it is preferable that the adhesive includes inorganic fillers.

Accordingly, it is possible to use the inorganic filler as a cap material that regulates the distance between the force detecting element and the bottom surface, and to enhance uniformity of the thickness of the adhesive positioned between the force detecting element and the bottom surface. In addition, by using the inorganic filler, it is possible to enhance mechanical strength of the adhesive.

In the sensor device according to the aspect of the invention, it is preferable that the inorganic filler includes a first filler and a second filler, and the maximum diameter of the first filler is greater than the maximum diameter of the second filler.

With this configuration, it is easy to control the thickness of the adhesive to a desired thickness, and it is possible to control characteristics of the resin material. In other words, the first filler functions as a cap material that regulates the distance between the force detecting element and the bottom surface of the recess, and easily controls the thickness of the adhesive to a desired thickness by using the first filler. In addition, it is possible to adjust the viscosity of the adhesive before being cured and the mechanical characteristics of the adhesive after being cured by using the second filler.

In the sensor device according to the aspect of the invention, it is preferable that the adhesive is a cured product of a liquid adhesive.

With this configuration, for example, it is possible to reduce or avoid entrance of bubbles between the force detecting element and the bottom surface, and to enhance the adhesive strength by the adhesive between the force detecting element and the bottom surface.

In the sensor device according to the aspect of the invention, it is preferable that a part of the adhesive is positioned between the force detecting element and a side surface of the recess.

With this configuration, it is possible to further stably position the force detecting element in the recess. In addition, for example, in a case where the bottom surface of the recess is configured to include a metal material, it is possible to prevent a short circuit due to the contact between the adhesive and the bottom surface.

In the sensor device according to the aspect of the invention, it is preferable that the force detecting element has a base material which supports the piezoelectric element and adheres to the adhesive, and the part positioned between the force detecting element of the adhesive and the side surface of the recess is positioned closer to the bottom surface side than the piezoelectric element provided on the base material.

With this configuration, for example, it is possible to reduce or prevent the adhesive from adhering to, for example, the electrode (side electrode) provided in the force detecting element or the terminal provided in the base.

In the sensor device according to the aspect of the invention, it is preferable that a lid which blocks an opening of the recess is further provided.

With this configuration, it is possible to accommodate the force detecting element in a space formed in the base and the lid, and to airtightly seal the inside of the space. Therefore, it is possible to reduce deterioration of the detection accuracy due to an external factor of the force detecting element.

In the sensor device according to the aspect of the invention, it is preferable that at least a part of the lid overlaps the force detecting element when viewed from the direction in which the force detecting element and the bottom surface overlap each other.

With this configuration, it is possible to dispose the force detecting element between the base and the lid. Therefore, for example, it is possible to reduce deterioration of robustness by pressurizing the force detecting element from both of the base and the lid. As a result, it is possible to further reduce deterioration of the detection accuracy of the force detecting element.

In the sensor device according to the aspect of the invention, it is preferable that the piezoelectric element includes quartz crystal.

With this configuration, it is possible to realize a force detection device having excellent characteristics, such as high sensitivity, wide dynamic range, and high rigidity.

A force detection device according to another aspect of the invention includes: a first board; a second board; the sensor device provided between the first board and the second board; and an external force detection circuit which detects the external force based on the signal from the sensor device, in which the sensor device includes: a base having a recess; a force detecting element which is provided in the recess, and includes at least one piezoelectric element that outputs a signal in accordance with an external force; an adhesive which is provided between the force detecting element and a bottom surface of the recess, and has insulating properties; at least one electrode provided in the force detecting element; at least one terminal provided in the base; and at least one conductive paste which electrically connects the electrode and the terminal to each other, in which the conductive paste has a part that overlaps the adhesive when viewed from a direction in which the force detecting element and the bottom surface overlap each other, in which the bottom surface has a part made of metal, and in which the force detecting element overlaps the part made of the metal on the bottom surface when viewed from the direction in which the force detecting element and the bottom surface overlap each other.

According to the force detection device, it is possible to detect the external force with high accuracy. A robot according to still another aspect of the invention includes a support base; an arm which is connected to the support base; and the force detection device, in which the force detection device includes: a first board; a second board; the sensor device provided between the first board and the second board; and an external force detection circuit which detects the external force based on the signal from the sensor device, in which the sensor device includes: a base having a recess; a force detecting element which is provided in the recess, and includes at least one piezoelectric element that outputs a signal in accordance with an external force; an adhesive which is provided between the force detecting element and a bottom surface of the recess, and has insulating properties; at least one electrode provided in the force detecting element; at least one terminal provided in the base; and at least one conductive paste which electrically connects the electrode and the terminal to each other, in which the conductive paste has a part that overlaps the adhesive when viewed from a direction in which the force detecting element and the bottom surface overlap each other, in which the bottom surface has a part made of metal, and in which the force detecting element overlaps the part made of the metal on the bottom surface when viewed from the direction in which the force detecting element and the bottom surface overlap each other.

According to the robot, it is possible to perform work more precisely.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a sensor device, a force detection device, and a robot according to the invention will be described in detail based on preferred embodiments illustrated in the attached drawings. In addition, in the drawings, the parts to be described are displayed as being appropriately enlarged or reduced so as to achieve a state where the parts can be recognized.

1. Force Detection Device

First, the force detection device according to the invention will be described.

FIG. 1is a perspective view illustrating a force detection device including a sensor device according to an appropriate embodiment of the invention.FIG. 2is a longitudinal sectional view of the force detection device illustrated inFIG. 1.FIG. 3is a horizontal sectional view of the force detection device illustrated inFIG. 2.FIG. 4is a sectional view of the sensor device included in the force detection device illustrated inFIGS. 2 and 3.FIG. 5is a sectional view of a force detecting element included in the sensor device illustrated inFIG. 4.FIG. 6is a view of the inside of the sensor device illustrated inFIG. 4when viewed from a lamination direction.FIG. 7is an enlarged view of a part of the sensor device illustrated inFIG. 4.FIG. 8is a view schematically illustrating an adhesive member included in the sensor device illustrated inFIG. 4.FIG. 9is a view illustrating a relationship between the thickness of an adhesive member of the sensor device illustrated inFIG. 4and a strain amount. In addition,FIG. 2is a sectional view taken along line A2-A2inFIG. 3, andFIG. 3is a sectional view taken along line A1-A1inFIG. 2. In addition, inFIG. 4, illustration of an analog circuit board6is omitted. In addition, inFIG. 8, a ratio of dimensions of a filler442aand a filler442bis different from the actual ratio.

In addition, for convenience of the description, inFIG. 1, an x-axis, a y-axis, and a z-axis are illustrated as three axes orthogonal to each other, and a tip end side of the arrow indicating each axis is “+”, a base end side is “−”. In addition, a direction parallel to the x-axis is referred to as “x-axis direction”, a direction parallel to the y-axis as “y-axis direction”, and a direction parallel to the z-axis as “z-axis direction”. In addition, the +z-axis direction side is also referred to as “up”, and the −z-axis direction side is referred to as “down”. In addition, what is seen from the z-axis direction is referred to as “planar view”.

The force detection device1illustrated inFIG. 1is a six-axis force sensor which is capable of detecting six-axis components of an external force applied to the force detection device1. Here, the six-axis component includes a translational force (shearing force) component in each direction of three mutually orthogonal axes (the x-axis, the y-axis, and the z-axis in the drawing), and a rotational force (moment) component around the axes of each of the three axes.

As illustrated inFIGS. 1 to 3, the force detection device1includes a plurality (four in this embodiment) of sensor devices4having at least one (plural) piezoelectric elements5, and a case200which accommodates a plurality of sensor devices4therein. In addition, the force detection device1also has a through-hole101formed along a center axis A1thereof. In addition, as illustrated inFIG. 3, the force detection device1includes a plurality (eight in the embodiment) of pressurizing bolts51, a plurality of (four in the embodiment) analog circuit boards6, and a digital circuit board (not illustrated).

In the force detection device1, signals (detection results) which corresponds to the external forces received by each of the sensor devices4are output, and the signals are processed by the analog circuit board6and the digital circuit board (not illustrated). Accordingly, the six-axis component of the external force applied to force detection device1is detected. Here, in the embodiment, the analog circuit board6and the digital circuit board (not illustrated) configure an external force detection circuit60which detects the external force based on the signal from the sensor device4.

Hereinafter, each part of the force detection device1will be described below.

As illustrated inFIG. 1, the case200includes a first case member3; a second case member2disposed with an interval with respect to the first case member3; and a side wall portion20(third case member) provided on the outer circumferential portion of the first case member3and the second case member2.

First Case Member

As illustrated inFIG. 2, the first case member3includes a top plate31(a first base portion), and a plurality of wall portions33(first pressurizing portion) provided on the lower side of the top plate31and in the outer circumferential portion. Although the outer shape of the first case member3in a plan view is circular as illustrated inFIG. 1, not being limited thereto, for example, a polygon, such as a quadrangle or a pentagon, or an ellipse, may be employed.

As illustrated inFIG. 2, the top plate31has a shape of a substantially flat plate. On the lower side of the top plate31, a plurality (four in the embodiment) of wall portions33are erected toward the second case member2side. In addition, in the drawing, each of the wall portions33is formed as a separate member from the top plate31and fixed to the top plate31, but may be integrally formed with the top plate31. As illustrated inFIG. 3, the plurality of wall portions33are arranged at equivalent angular (90°) intervals along the same circumference around a center axis A1of the force detection device1. In each of the wall portions33, a plurality of through-holes37through which the pressurizing bolt51that will be described later is inserted are formed. In addition, as illustrated inFIG. 2, the inner wall surface331(inner end surface) of each of the wall portions33is a plane perpendicular to the top plate31.

In addition, the first case member3has a through-hole35formed along the central axis A1at the center portion thereof.

An upper surface301of the first case member3having such a configuration functions, for example, as an attachment surface to be attached to an end effector17(attached member) included in a robot100which will be described later.

In addition, the configuration material of the first case member3is not particularly limited, but metal materials, such as aluminum or stainless steel, ceramics and the like can be employed.

Second Case Member

As illustrated inFIG. 2, the second case member2includes a bottom plate21(second base portion), and a plurality of wall portions22(second pressurizing portion) provided on the upper side of the bottom plate21. Although the outer shape of the second case member2in a plan view is circular as illustrated inFIG. 1, not being limited thereto, for example, a polygon, such as a quadrangle or a pentagon, or an ellipse, may be employed.

As illustrated inFIG. 2, the bottom plate21has a shape of a substantially flat plate. On the upper side of the bottom plate21, a plurality (four in the embodiment) of wall portions22are erected toward the first case member3side. In addition, in the drawing, each of the wall portions22is formed as a separate member from the bottom plate21and fixed to the bottom plate21, but may be integrally formed with the bottom plate21. As illustrated inFIG. 3, the plurality of wall portions22are arranged at equivalent angular (90°) intervals along the same circumference around a center axis A1of the force detection device1. Each of the wall portions22is disposed on the center axis A1side with respect to the wall portion33of the above-described first case member3, and faces the wall portion33. In addition, on the wall portion33side of the wall portion22, apart23which protrudes toward the wall portion33side is provided. A top surface231of the protruding part23faces the inner wall surface331of the wall portion33at a predetermined distance (distance in which the sensor device4can be inserted). In addition, the top surface231and the inner wall surface331are parallel to each other. In addition, a plurality of female screw holes26are formed in each of the wall portions22so that a tip end portion of the pressurizing bolt51which will be described later is screwed thereto.

In addition, the second case member2has a through-hole25formed along the central axis A1at the center portion thereof.

A lower surface201of the second case member2functions as, for example, an arm attachment surface for attaching the force detection device1to an arm16of the robot100which will be described later.

In addition, the configuration material of the second case member2is not particularly limited, but similar to the above-described first case member3, metal materials, such as aluminum or stainless steel, ceramics and the like can be employed. In addition, the configuration material of the second case member2may be the same as or different from the configuration material of the first case member3.

Side Wall Portion

As illustrated inFIG. 1, the side wall portion20(third case member) has a cylindrical shape, and the upper end portion and the lower end portion thereof are screwed to the first case member3and the second case member2, respectively, and is fixed by fitting or the like. In addition, as illustrated inFIG. 2, in a space S surrounded by the side wall portion20, the top plate31of the first case member3, and the bottom plate21of the second case member2, which are described above, that is, the inner space of the force detection device1, a plurality of sensor devices4are accommodated.

In addition, the configuration material of the side wall portion20is not particularly limited, but similar to the above-described first case member3or second case member2, for example, metal materials, such as aluminum or stainless steel, ceramics and the like can be employed. In addition, the configuration material of the side wall portion20may be the same as or different from the configuration material of the first case member3or the second case member2.

Sensor Device

As illustrated inFIG. 3, the four sensor devices4are disposed so as to be symmetrical to a line segment CL that passes through the center axis A1and is parallel to the y-axis when viewed from the direction along the center axis A1(z-axis direction). In addition, when viewed from a direction orthogonal to the center axis A1(in a side view inFIG. 2), each of the sensor devices4is positioned in an intermediate portion between the top plate31of the first case member3and the bottom plate21of the second case member2. In addition, as illustrated inFIG. 4, each of the sensor devices4is disposed between the wall portion33of the first case member3and the wall portion22of the second case member2. In addition, each of the sensor devices4is sandwiched between the wall portion33and the wall portion22.

Each of the sensor devices4has a force detecting element41(force detecting unit), a package42that accommodates the force detecting element41, and an adhesive member44that adheres to the force detecting element41to the package42. In addition, each of the sensor devices4includes: a plurality of (four in the embodiment) side electrodes45(electrodes) provided in the force detecting element41; a plurality of (four in the embodiment) terminals47provided in the package42; and a plurality of (four in the embodiment) connecting portions46which electrically connects the side electrode45and the terminal47to each other.

Force Detecting Element

The force detecting element41illustrated inFIG. 5has a function of outputting an electric charge QX that corresponds to a component in the X-axis direction of the external force applied to the force detecting element41, an electric charge QY that corresponds to the component in the Y-axis direction of the external force applied to the force detecting element41, and an electric charge QZ that corresponds to the component in the Z-axis direction of the external force applied to the force detecting element41. The force detecting element41includes: a piezoelectric element5awhich outputs the electric charge QX in accordance with the external force (shearing force) parallel to the X-axis; a piezoelectric element5bwhich outputs the electric charge QZ in accordance with the external force (compression/tensile force) parallel to the Z-axis; a piezoelectric element5cwhich outputs the electric charge QY in accordance with the external force (shearing force) parallel to the Y-axis; and ground electrode layers54,55,56, and57which are electrically connected to a reference potential (for example, ground potential GND). In addition, the force detecting element41has support substrates58and59(base material) for supporting a structure body50including the piezoelectric elements5a,5b,and5cand the ground electrode layers54,55,56, and57. Here, the support substrate58, the ground electrode layer54, the piezoelectric element5a,the ground electrode layer55, the piezoelectric element5b,the ground electrode layer56, the piezoelectric element5c,the ground electrode layer57, and the support substrate59are laminated in this order. In addition, hereinafter, each of the piezoelectric elements5a,5b,and5cis also referred to as a “piezoelectric element5”.

The piezoelectric element5ais configured by laminating a piezoelectric layer51a,an output electrode layer52a,and a piezoelectric layer53ain this order. Similarly, the piezoelectric element5bhas piezoelectric layers51band53b,and an output electrode layer52bdisposed therebetween. In addition, the piezoelectric element5chas piezoelectric layers51cand53c,and an output electrode layer52cdisposed therebetween.

The piezoelectric element5includes quartz crystal. In other words, the piezoelectric element5includes the piezoelectric layers51a,53a,51b,53b,51c,and53cformed of quartz crystal. Accordingly, it is possible to realize the force detection device1having excellent characteristics, such as high sensitivity, wide dynamic range, and high rigidity.

As illustrated inFIG. 5, in the piezoelectric element5, the direction of the X-axis which is a crystal axis of quartz crystal that configures the piezoelectric layers51a,53a,51b,53b,51c,and53cvaries. In other words, the X-axis of the quartz crystal that configures the piezoelectric layer51afaces a far side of the paper surface inFIG. 5. The X-axis of the quartz crystal that configures the piezoelectric layer53afaces a near side of the paper surface inFIG. 5. The X-axis of the quartz crystal that configures the piezoelectric layer51bfaces an upper side inFIG. 5. The X-axis of the quartz crystal that configures the piezoelectric layer53bfaces a lower side inFIG. 5. The X-axis of the quartz crystal that configures the piezoelectric layer51cfaces a right side inFIG. 5. The X-axis of the quartz crystal that configures the piezoelectric layer53cfaces a left side inFIG. 5. Each of the piezoelectric layers51a,53a,51c,and53cis formed of a Y-cut quartz crystal plate, and the X-axis directions are different from each other by 90 degrees. In addition, each of the piezoelectric layers51band53bis configured of an X-cut quartz crystal plate, and the directions of the X-axis are different from each other by 180°.

In addition, in the embodiment, each of the piezoelectric layers51a,53a,51b,53b,51c,and53cis made of quartz crystal, respectively, but may be configured by using a piezoelectric material other than quartz crystal. Examples of the piezoelectric materials other than quartz crystal include topaz, barium titanate, lead titanate, lead titanate zirconate (PZT: Pb(Zr,Ti)O3), lithium niobate, lithium tantalate and the like.

In addition, materials which configure the output electrode layers52a,52b,and52cand the ground electrode layers54,55,56, and57are not particularly limited as long as the materials can each function as an electrode, and examples thereof include nickel, gold, titanium, aluminum, copper, iron, chromium, an alloy containing these, and the like, and one type or two or more types of these can be used in combination (for example, by laminating).

In addition, in the embodiment, each of the support substrates58and59is configured of quartz crystal, but may be made of a material having no conductivity other than quartz crystal.

Although the overall shape of the force detecting element41is a rectangular parallelepiped, not being limited thereto, for example, a cylindrical shape or another polyhedron may be employed. In addition, each of the force detecting elements41is disposed so that a lamination direction D1of the piezoelectric elements5a,5b,and5cis orthogonal to the center axis A1(in the plane direction of the yz plane) (refer toFIGS. 4 and 5). In addition, in the embodiment, for example, the support substrate58is positioned on the wall portion33side and the support substrate59is positioned on the wall portion22side. In addition, the support substrate58may be positioned on the wall portion22, and the support substrate59may be positioned on the wall portion33side.

In addition, as described above, the force detecting element41includes a plurality of piezoelectric elements5. Accordingly, it is possible to increase the sensitivity of the force detection device1, and to achieve multiaxial detection axes. In addition, the number of piezoelectric elements5and piezoelectric layers which configure the force detecting element41is not limited to the above-mentioned number. For example, the number of piezoelectric layers included in one piezoelectric element5may be one or three or more, or the number of piezoelectric elements5may be two or four or more.

Here, in the embodiment, as described above, each of the sensor devices4is disposed so that the lamination direction D1of the piezoelectric element5is orthogonal to the center axis A1, and the four sensor devices4are disposed to be symmetrical to each other with respect to the line segment CL (refer toFIGS. 3 and 5). In addition, as described above, the wall portion33and the wall portion22apply a pressure in a direction parallel to the lamination direction D1of the piezoelectric element5. Therefore, in the digital circuit board, it is possible to calculate translational force components Fx, Fy, and Fz and rotational force components Mx, My, and Mz (that is, external forces) without using the electric charge QZ that is likely to receive influence of the temperature fluctuation. Therefore, the force detection device1is less likely to receive influence of temperature fluctuations, and high-precision detection is possible. Accordingly, for example, the force detection device1is placed under a high temperature environment, the first case member3and the second case member2thermally expands, and a case where the pressure applied to the piezoelectric element5changes from a predetermined value due to the thermal expansion, and becomes noise component, can be reduced or set to be zero.

Package

As illustrated inFIG. 4, the package42includes: a base portion43(supporting member, first member, and base) having a recess portion433(recess) in which the force detecting element41is installed; and a lid body49(member, second member, and lid) joined to the base portion43via a seal member48so as to close an opening of the recess portion433. In addition, the force detecting element41including at least one piezoelectric element5is installed (accommodated) in a space S1(internal space of the package42) surrounded by the base portion43and the lid body49, that is, within the recess portion433. Accordingly, the force detecting element41can be protected. Here, the base portion43abuts against the top surface231of the above-described second case member2. Meanwhile, the lid body49abuts against the inner wall surface331of the above-described first case member3.

Base Portion

The base portion43has a flat plate-like bottom member431and a side wall member432joined (fixed) to the bottom member431. The recess portion433is formed by the bottom member431and the side wall member432.

The bottom member431abuts against the top surface231of the second case member2and the force detecting element41, and has a function of transmitting the external force applied to the second case member2to the force detecting element41.

The side wall member432has a rectangular tubular shape, and has a protrusion portion4320that protrudes toward the inside of the recess portion433. The protrusion portion4320is formed over the entire circumference of the side wall member432(formed in an annular shape) and adheres onto the bottom member431. In addition, a terminal47is provided on the surface of the protrusion portion4320on the lid body49side, that is, a step portion4321. In addition, the step portion4321is formed over the entire circumference of the side wall member432, and surrounds the outer edge portion of the base portion43.

An inner wall surface434(surface on which the recess portion433is formed) of the base portion43is configured with a bottom surface4341and a side surface4342. The bottom surface4341is configured with the upper surface of the bottom member431inFIG. 4. The side surface4342is configured with the inner wall surface434of the side wall member432including the step portion4321. On the bottom surface4341, the force detecting element41is provided via the adhesive member44.

In addition, examples of the configuration material of the bottom member431of the base portion43include various metal materials, such as stainless steel, Kovar, copper, iron, carbon steel, titanium and the like, and among these, Kovar is particularly preferable. Accordingly, the bottom member431has relatively high rigidity and is elastically deformed appropriately when stress is applied. Therefore, the bottom member431can accurately transmit the external force applied to the second case member2to the force detecting element41, and it is possible to further reduce the damage due to the external force. In addition, Kovar is also preferable from the viewpoint of excellent moldability.

In addition, it is preferable that the bottom member431is configured of a single material. Accordingly, it is possible to equalize the longitudinal elastic modulus and the mechanical strength over the entire bottom member431. In addition, when viewed from a direction of the arrow A3(lamination direction D1) (a normal line direction of the bottom surface4341of the bottom member431of the base portion43) inFIG. 4, at least a region that overlaps with the force detecting element41of the base portion43is configured of a metal material, and accordingly, it is possible to remarkably achieve an effect of further reducing damage of the base portion43due to the external force.

Meanwhile, as a configuration material of the side wall member432of the base portion43, it is preferable to use a material having insulating properties, and for example, various ceramics, such as oxide-based ceramic (for example, alumina or zirconia), carbide-based ceramics (for example, silicon carbide), nitride-based ceramics (for example, silicon nitride) or the like, are preferable as main components. Ceramics have appropriate rigidity and excellent insulating properties. Therefore, damage due to deformation of the package42hardly occurs, and the force detecting element41accommodated therein can be protected more reliably. In addition, it is possible to more reliably avoid short-circuiting between the terminals47. In addition, the processing accuracy of the side wall member432can be further enhanced.

In addition, it is preferable that the side wall member432is configured of a single material. Accordingly, it is possible to equalize the longitudinal elastic modulus and the mechanical strength over the entire bottom member431. In addition, in the configuration illustrated in the drawing, the bottom member431and the side wall member432are provided by joining (fixing) separate members, but the bottom member431and the side wall member432may be integrally formed.

Sealing Member

As illustrated inFIG. 4, the seal member48is disposed at the entire circumference of the upper surface of the base portion43. As the configuration material of the seal member48, any material may be used as long as the material has a function of joining (adhering) the lid body49to the base portion43, for example, gold, silver, titanium, aluminum, copper, iron, or alloy of these materials can be used.

Lid Body

The lid body49has a shape of a plate, and is joined to the base portion43via the seal member48so as to close the opening of the recess portion433. The lid body49is provided to abut against the wall portion33of the first case member3and the force detecting element41, and has a function of transmitting the external force applied to the first case member3to the force detecting element41. In addition, in the embodiment, the edge portion side of the lid body49is bent toward the base portion43side, and is provided so as to cover the force detecting element41.

The configuration material of the lid body49is not particularly limited, but similar to the above-described bottom member431, examples thereof can include various metallic materials, such as stainless steel, Kovar, copper, iron, carbon steel, titanium and the like, and among these, Kovar is preferable. Accordingly, similar to the bottom member431, the external force can be accurately transmitted by the force detecting element41, and it is possible to further reduce the damage due to the external force. In addition, although the configuration material of the lid body49may be the same as or different from the configuration material of the bottom member431, it is preferable that the configuration materials are the same. Accordingly, the external force applied to the package42can be accurately transmitted by the force detecting element41.

Although the shape of the package42in a plan view is a quadrangle in the embodiment, the shape is not limited thereto, and another polygon, such as a pentagon, a circle, an ellipse, or the like may be employed.

In the package42described above, the bottom surface4341of the recess portion433has a part made of metal. In particular, as described above, it is preferable that the base portion43is made of a metal (particularly, Kovar). Accordingly, mechanical strength, such as brittleness of the bottom surface4341can be enhanced.

Furthermore, as described above, the force detecting element41that serves as the “force detecting unit” overlaps a part made of metal of the bottom surface4341when viewed from a direction in which the force detecting element41and the bottom surface4341overlap each other (viewed from the direction of arrow A3inFIG. 4). Accordingly, it is possible to reduce or avoid occurrence of damage, such as cracks, on the bottom surface4341due to a load from the force detecting element41on the bottom surface4341.

In addition, as described above, the sensor device4has the lid body49that serves as the “second member” which closes the opening of the recess portion433. Accordingly, the force detecting element41is accommodated in the space S1formed by the base portion43and the lid body49, and the space S1can be airtightly sealed. Therefore, it is possible to reduce deterioration of detection accuracy due to an external factor of the force detecting element41.

In addition, at least a part of the lid body49that serves as the “second member” overlaps the force detecting element41when viewed from the direction in which the force detecting element41that serves as the “force detecting unit” and the bottom surface4341overlap each other (when viewed from the direction of the arrow A3inFIG. 4). Accordingly, the force detecting element41can be disposed between the base portion43and the lid body49. Therefore, it is possible to pressurize the force detecting element41from both of the base portion43and the lid body49by being sandwiched by the wall portions22and33, for example, it is possible to reduce deterioration of robustness. As a result, it is possible to reduce deterioration of detection accuracy of the force detecting element41.

In the force detecting element41, at least one side electrode45is provided, and a plurality of side electrodes45are provided in the configuration illustrated inFIGS. 4 and 6. As illustrated inFIGS. 4 and 6, a plurality of (four in the embodiment) side electrodes45are provided on the side surface of the force detecting element41. In addition, in the following description, among the four side electrodes45, the side electrode45positioned on the upper left side inFIG. 6is referred to as “side electrode45a”, the side electrode45positioned on the lower left side inFIG. 6is referred to as “side electrode45b”, the side electrode45positioned on the upper right side inFIG. 6is referred to as “side electrode45c”, and the side electrode45positioned on the lower right side inFIG. 6is referred to as “side electrode45d”. In addition, in a case where each of the side electrodes45a,45b,45c,and45dis not distinguished, the side electrodes45a,45b,45c,and45dare referred to as “side electrode45”. In addition, the number of side electrodes45is not particularly limited, and may be one.

The side electrode45ais electrically connected to the output electrode layer52aof the force detecting element41. Similarly, the side electrode45bis electrically connected to the output electrode layer52bof the force detecting element41, and the side electrode45cis electrically connected to the output electrode layer52cof the force detecting element41. In addition, the side electrode45ais electrically connected to the ground electrode layers54,55,56, and57of the force detecting element41. The side electrodes45aand45bare provided to be separated from each other on the same side surface of the force detecting element41. In addition, the side electrodes45cand45dare provided to be separated from each other on the same side surface that opposes the side surface on which the side electrodes45aand45bare provided. In addition, each of the side electrodes45a,45b,45c,and45dmay be provided on the same surface of the force detecting element41, or may be provided on different surfaces.

In addition, each of the side electrodes45has an elongated shape along the lamination direction D1of the force detecting element41. In the embodiment, each of the side electrodes45has an elongated shape which extends from the support substrate58to the middle of the support substrate59. In addition, each of the side electrodes45can be formed by, for example, a sputtering method, a plating method, or the like. With such a configuration, each of the side electrodes can be easily formed. In addition, examples of the configuration material of each of the side electrodes45include nickel, gold, titanium, aluminum, copper, iron and the like, and one type or two or more types of these can be used in combination. In particular, it is preferable that each of the side electrodes45is made of a material containing nickel (Ni). Nickel is preferable because nickel has a thermal expansion coefficient close to the thermal expansion coefficients of the piezoelectric layers51a,53a,51b,53b,51c,and53c.

Terminal

In the base portion43, at least one terminal47is provided, and a plurality of terminals47are provided in the configuration illustrated inFIGS. 4 and 6. As illustrated inFIG. 4andFIG. 6, a plurality of (four in the embodiment) terminals47are provided in the step portion4321of the above-described base portion43. In addition, in the following description, among the four terminals47, the terminal47positioned on the upper left side inFIG. 6is referred to as “terminal47a”, the terminal47positioned on the lower left side inFIG. 6is referred to as “terminal47b”, the terminal47positioned on the upper right side inFIG. 6is referred to as “terminal47c”, and the terminal47positioned on the lower right side inFIG. 6is referred to as “terminal47d”. In addition, in a case where each of the terminals47a,47b,47c,and47dis not distinguished, the terminals47a,47b,47c,and47dare referred to as “terminals47”. In addition, the number of terminals47is not particularly limited, and may be one.

The terminal47ais provided in the vicinity of the side electrode45a.Similarly, the terminal47bis provided in the vicinity of the side electrode45b,the terminal47cis provided in the vicinity of the side electrode45c,and the terminal47dis provided in the vicinity of the side electrode45d.

Each of the terminals47is electrically connected to the analog circuit board6via wirings (not illustrated) provided on the base portion43(refer toFIGS. 2 to 4).

In addition, each of the terminals47may have conductivity, and may be formed by laminating each film, such as nickel, gold, silver, or copper, on a metallization layer (ground layer), such as chromium, tungsten, or the like.

Connecting Portion

The sensor device4includes at least one connecting portion46, and includes a plurality of connecting portions46in the configuration illustrated inFIGS. 4 and 6. As illustrated inFIG. 4, a plurality of (four in the embodiment) connecting portions46electrically connect the above-described terminal47and the side electrode45. In addition, in the following description, among the four connecting portions46, the connecting portion46positioned on the upper left side inFIG. 6is referred to as “connecting portion46a”, the connecting portion46positioned on the lower left side inFIG. 6is referred to as “connecting portion46b”, the connecting portion46positioned on the upper right side inFIG. 6is referred to as “connecting portion46c”, and the connecting portion46positioned on the lower right side inFIG. 6is referred to as a “connecting portion46d”. In addition, in a case where each of the connecting portions46a,46b,46c,and46dis not distinguished, the connecting portions46a,46b,46c,and46dare referred to as “connecting portion46”. In addition, the number of connecting portions46is not particularly limited, and may be one.

The connecting portion46aadheres to the side electrode45aand the terminal47a,and electrically connects the side electrode45aand the terminal47ato each other. Similarly, the connecting portion46badheres to the side electrode45band the terminal47b,and electrically connects the side electrode45band the terminal47bto each other. The connecting portion46cadheres to the side electrode45cand the terminal47c,and electrically connects the side electrode45cand the terminal47cto each other. The connecting portion46dadheres to the side electrode45dand the terminal47d,and electrically connects the side electrode45dand the terminal47dto each other.

In addition, examples of configuration materials of each of the connecting portions46include gold, silver, copper, or the like, and one type or two or more types of these can be used in combination. In addition, each of the connecting portions46may be specifically formed of, for example, Ag paste, Cu paste, Au paste or the like, but it is particularly preferable to use Ag paste. The Ag paste is easy to obtain and excellent in handleability.

Adhesive Member

As illustrated inFIGS. 4 and 6, the adhesive member44is a member having an insulating property, and is provided between the force detecting element41and the base portion43. Specifically, the adhesive member44is provided between the bottom surface4341of the recess portion433and the force detecting element41, and between the side surface4342of the recess portion433and the force detecting element41. In other words, the adhesive member44has a part444positioned between the bottom surface4341of the recess portion433and the force detecting element41, and a part445positioned between the side surface4342of the recess portion433and the force detecting element41.

The part444of the adhesive member44overlaps the force detecting element41when viewed from the direction of the arrow A3inFIG. 4and encloses the force detecting element41(refer toFIGS. 4 and 6). Furthermore, the part444of the adhesive member44also overlaps a part of the adhesive member44when viewed from the direction of the arrow A3. In addition, as illustrated inFIG. 7, the part445of the adhesive member44is not in contact with the connecting portion46, but is provided with a gap S2between the connecting portion46and the part445.

In addition, a height T1of the part445is smaller than the total height T2of the height of the support substrate59of the force detecting element41and the height of the part444of the adhesive member44. Accordingly, it possible to reduce or prevent the adhesive member44from coming into contact with the side electrode45or the connecting portion46and hindering the conduction between the side electrode45and the connecting portion46.

The adhesive member44is made of a member having higher bending strength and flexural modulus than those of the base portion43and the force detecting element41. The bending strength of the adhesive member44is approximately 100 MPa or greater and 300 MPa or less, and the bending elastic modulus of the adhesive member44is approximately 4000 MPa or greater and about 6000 MPa or less. Since the adhesive member44is provided between the force detecting element41and the base portion43, it is possible to further reduce the damage of the force detecting element41or the base portion43due to an external force.

In addition, the adhesive member44is made of a cured product of an adhesive. Examples of the form of the adhesive include a liquid state (including a semi-solid state, such as a paste state) or a solid state in the form of a sheet or a film. Among these, it is particularly preferable to use a liquid adhesive. In other words, it is preferable that the adhesive member44is a cured product of a liquid adhesive. Accordingly, when adhering the force detecting element41to the base portion43, it is possible to reduce the generation of bubbles or residual bubbles between the force detecting element41and the base portion43. Therefore, it is possible to reduce deterioration of the adhering strength of the force detecting element41with respect to the base portion43. In addition, the term “liquid state” refers to a state having fluidity at room temperature (25° C.), and the solid state refers to a state having no fluidity at room temperature (25° C.). In addition, for example, a material which flows when the adhesive is disposed to be tilted in a flat plate-like member by self-weight thereof, is made liquid.

In addition, in the embodiment, the adhesive includes a resin material that is capable of performing curing reaction and the filler442a(first filler) and the filler442b(second filler) (refer toFIG. 8). In addition, the adhesive may appropriately contain water, a solvent, a plasticizer, a curing agent, an antistatic agent and the like.

As the resin material, it is possible to use a curable resin, such as a thermoplastic resin, a plastic resin (for example, a thermoplastic resin), a thermosetting resin, a photocurable resin, and an electron beam curable resin, and among these, it is preferable to use a curable resin (a resin material that can react to the curing), and it is more preferable to use a thermosetting resin. Examples of the thermosetting resin include acrylic resins, phenolic resins, silicone resin-based resins, epoxy resins and the like, and among these, it is preferable to use epoxy resins. Epoxy resins are particularly excellent in tensile shear adhering strength. Here, in the embodiment, as described above, by sandwiching the force detecting element41between the wall portions22and33via the base portion43and the lid body49, the strength in a direction (lamination direction D1) of pushing the force detecting element41of the base portion43against the bottom member431is guaranteed, but the strength in the shearing direction (z-axis direction) is insufficient. Therefore, as described above, the strength in the shearing direction of the force detecting element41can be sufficiently ensured by using an epoxy resin having particularly excellent tensile shear adhering strength.

The content of the resin material in the adhesive is preferably 50% by weight or greater, and more preferably 70% by weight or greater and 95% by weight or less. In addition, in a case where a solvent or water is contained, the above-described content indicates the solid content excluding these.

The filler442afunctions as a gap material that regulates a distance between the force detecting element41and the bottom surface4341and regulates a thickness D of the adhesive member44. The maximum diameter (maximum width) of the filler442ais greater than the maximum diameter (maximum width) of the filler442b.Accordingly, by using the filler442a,it is easy to control the thickness D of the adhesive member44to a desired thickness.

The filler442bcontrols the properties of the resin material. By using the filler442b,it is possible to adjust the resin viscosity (viscosity of the adhesive member44before being cured) of the resin material, and to adjust the mechanical properties after being cured (mechanical properties of the adhesive member44after being cured). In particular, it is relatively difficult to adjust the viscosity of the adhesive member44before being cured only by the filler442a,but by using the filler442b,it is possible to easily adjust the viscosity of the adhesive member44before being cured.

As the configuration material of the fillers442aand442b,it is preferable to use inorganic fillers containing inorganic oxides, such as silica (SiO2) and alumina (Al2O3), and inorganic materials, such as ceramics and glass, and one type or two or more types fillers among the materials can be used in combination. Among these materials, in particular, it is preferable to use silica and alumina as the configuration material of the fillers442aand442b.Accordingly, the mechanical strength or heat resistance of the adhesive member44can be enhanced. In addition, it is preferable that the fillers442aand442bhave no conductivity (insulating properties). Accordingly, the conductivity of the adhesive member44can be further reduced.

As the shape of the fillers442aand442b,a spherical shape is preferable, but the shape is not particularly limited thereto, and it is possible to use spherical, rectangular, plate-like, needle-shaped, or leaf-like fillers. By making the fillers442a,442binto a spherical shape, classification can be performed, and the size of the diameter can be made uniform. In addition, it is easy to control the adhesive member44to a desired thickness D. In addition, the fillers442aand442bmay be a dense body or a porous body.

In addition, it is preferable that the maximum diameter (maximum thickness) of the filler442ais equal to or greater than 10 μm, and is more preferable that the maximum diameter is 10 μm or greater and 100 μm or less. Accordingly, it is easy to set the thickness D of the adhesive member44to be a desired thickness D (refer toFIG. 8). In other words, it is preferable that the maximum diameter (maximum width) of the filler442ais equal to the thickness D of the adhesive member44to be formed. Accordingly, it is possible to easily form the adhesive member44having the desired thickness D. In addition, it is preferable that an average diameter (average width) of the filler442ais 0.1 μm or greater or 100 μm or less, and is more preferable that the average diameter is 1 μm to 90 μm or less.

In addition, it is preferable that the maximum diameter (maximum width) of the filler442bis 1 nm or greater or 50 nm or less. Accordingly, it is possible to appropriately adjust the viscosity of the adhesive member44before being cured and the mechanical properties of the adhesive member44after being cured.

Here, the maximum diameter of the filler442ais a length of the longest part of the filler442a.For example, in a case where the shape of the filler442ais a sphere (spherical shape), the maximum diameter of the filler442ais a diameter of the sphere, and in a case where the shape of the filler442awhen viewed in a plan view is an ellipse (elliptical shape), the maximum diameter of the filler442ais a long diameter of the ellipse. In addition, the maximum diameter of the filler442bis also similar thereto.

The total content of the fillers442aand442bin the adhesive is not particularly limited, but it is preferable that the total content is 5% by weight or greater or 40% by weight or less, and is more preferable that the total content is 10% by weight or greater or 30% by weight or less. When the content is higher than the upper limit value, the adhering function of the adhesive member44deteriorates. In addition, when the content is lower than the lower limit value, the effects of the fillers442aand442bbecome insufficient. In a case where a solvent or water is contained, the above-described content indicates the solid content excluding these.

In this manner, in the embodiment, the adhesive member44includes the fillers442aand442b.It is preferable that the adhesive member44includes the inorganic filler. Accordingly, it is possible to use the filler442aconfigured of the inorganic filler as the cap material that regulates the distance between the force detecting element41and the bottom surface4341, and to enhance the uniformity of the thickness D of the adhesive member44positioned between the force detecting element41and the bottom surface4341. In addition, by using the inorganic filler, it is possible to enhance the mechanical strength of the adhesive member44. Furthermore, it is possible to use the filler442bconfigured of the inorganic filler for controlling the characteristics of the resin member, and to maintain the characteristics when initializing. In addition, by using the inorganic filler, it is possible to enhance mechanical characteristics of the adhesive member44.

It is preferable that the thickness D of the adhesive member44which is a cured product of the adhesive is 1 μm or greater or 100 μm or less, and is more preferable that the thickness D is 5 μm or greater or 90 μm. Accordingly, it is possible to sufficiently ensure the adhesive strength, and it is possible to reduce deterioration of the influence of the transmission of the external force.

Here, with reference toFIG. 9, the relationship between the thickness D of the adhesive member44and the strain amount of the force detecting element41will be described. A line segment L11inFIG. 9illustrates a case where the thickness D of the adhesive member44is 30 μm, a line segment L12illustrates a case where the thickness D of the adhesive member44is 100 μm, and a line segment L10illustrates a case where the force detecting element41is provided to directly abut against the bottom surface4341without interposing the adhesive member44.

As illustrated inFIG. 9, in a case where the thickness D of the adhesive member44is 30 μm, the strain amount (deformation amount) of the force detecting element41with respect to the pushing force (the size of the external force) of the force detecting element41is set to be a size equivalent to that in a case where the adhesive member44is not provided. In other words, in a case where the thickness D is 30 μm, the strain amount is equal to that in a case where the adhesive member44is not provided, and a transmission loss of the external force due to the provided adhesive member44is small (almost none).

Meanwhile, as illustrated inFIG. 9, in a case where the thickness D of the adhesive member44is 100 μm, the strain amount against the pushing force is greater than that in a case where the adhesive member44is not provided. This is because the transmission loss of the external force due to the provided adhesive member44increases. In addition, when the thickness D exceeds 100 μm, the strain amount further increases.

From the point of view described above, by setting the thickness D within the above-described range, it is possible to suppress an increase in flexibility (elasticity) of the adhesive member44due to an increase in thickness of the adhesive member44, and accordingly, it is possible to reduce the transmission loss of the external force due to the provided adhesive member44. As a result, even when the adhesive member44is provided, an external force can be transmitted to the force detecting element41similar to that in a case where the adhesive member44is not provided. In addition, when the thickness D of the adhesive member44is 100 μm or less, the transmission loss of external force can be made relatively small.

As described above, each of the sensor devices4described above includes: a base portion43that serves as a “first member” having a recess portion433; the force detecting element41that is installed in the recess portion433and serves as a “force detecting unit” including at least one piezoelectric element5that outputs a signal in accordance with the external force; and the adhesive member44provided between the force detecting element41and the bottom surface4341of the recess portion433. According to the force detection device1, since the force detecting element41can adhere to the bottom surface4341of the recess portion433by the adhesive member44, the stability of the position in the recess portion433of the force detecting element41can be enhanced. Therefore, it is possible to reduce deterioration of resistance against mechanical stress, such as vibration. As a result, it is possible to output a signal that corresponds to the external force with high accuracy, and thus, to improve the detection accuracy of the external force.

In addition, in the embodiment, the surface of the force detecting element41on the bottom surface4341side comes into contact with the adhesive member44throughout the entire region thereof. In other words, the adhesive member44is provided over the entire area between the force detecting element41and the bottom surface4341. When there is a part at which the adhesive member44is not provided in the region between the force detecting element41and the bottom surface4341, the stress is likely to concentrate on the part, but by providing the adhesive member44over the entire region between the force detecting element41and the bottom surface4341, local concentration of stress can be reduced or prevented. Therefore, a signal that corresponds to the external force can be output with higher accuracy.

In addition, as illustrated inFIG. 4, the sensor device4includes: the side electrode45(at least one side electrode45) that serves as “electrode” provided in the force detecting element41that serves as “force detecting unit”; a terminal47(at least one terminal47) provided in the base portion43that serves as “first member”; and the connecting portion46(at least one connecting portion46) which electrically connects the side electrode45and the terminal47to each other. Accordingly, for example, it is possible to electrically connect the force detecting element41to the external force detection circuit60which calculates the detection result (electric charge) output from the force detecting element41via the side electrode45, the connecting portion46, and the terminal47.

In addition, the connecting portion46has a part that overlaps the adhesive member44when viewed from the direction in which the force detecting element41that serves as “force detecting unit” and the bottom surface4341overlap each other (when viewed from the direction of the arrow A3inFIG. 4). Accordingly, it is possible to reduce or prevent the connecting portion46from coming into contact with the bottom surface4341of the recess portion433. Therefore, it is possible to prevent a short circuit due to the contact between the conductive base portion43and the connecting portion46.

In particular, as described above, the adhesive member44preferably has insulating properties. Accordingly, the connecting portion46can be prevented from coming into contact with the bottom surface4341, and a short circuit caused by the contact between the connecting portion46and the bottom surface4341can be reduced or prevented. In addition, for example, in addition to the base portion43, even in a case where the surface of the force detecting element41on the base portion43side is conductive (for example, in a case where the electrode is provided on the surface of the force detecting element41on the base portion43side), it is possible to reduce or prevent a short circuit due to contact between the bottom surface4341and the force detecting element41.

As described above, according to the sensor device4, by a synergistic effect by combining each of the above-described functions, it is possible to improve durability and reliability, and as a result, it is possible to improve detection accuracy.

In addition, as described above, the inorganic filler included in the adhesive member44includes the filler442a(first filler) and the filler442b(second filler), and the maximum diameter of the filler442a(first filler) is greater than the maximum diameter of the filler442b(second filler). Accordingly, it is easy to control the thickness D of the adhesive member44to a desired thickness, and to suppress characteristics of the resin material. In other words, the filler442afunctions as the cap material that regulates the distance between the force detecting element41and the bottom surface4341, and by using the filler442a,it is easy to control the thickness D of the adhesive member44to a desired thickness. In addition, by using the filler442b,it is possible to adjust the viscosity of the adhesive member44before being cured and the mechanical characteristics of the adhesive member44after being cured.

In addition, as described above, a part of the adhesive member44is positioned between the force detecting element41that serves as “force detecting unit” and the side surface4342of the recess portion433. Accordingly, it is possible to more stably dispose the force detecting element41in the recess portion433. In addition, since it is possible to reduce or prevent the contact of the connecting portion46with the bottom surface4341, it is possible to reduce or prevent a short circuit due to contact between the connecting portion46and the bottom surface4341.

Furthermore, as described above, the force detecting element41that serves as the “force detecting unit” includes the support substrate59that serves as the “base material” which supports the piezoelectric element5and adheres to the adhesive member44, and the part445of the adhesive member44positioned between the force detecting element41and the side surface4342of the recess portion433is positioned closer to the bottom surface4341side than the piezoelectric element5cprovided on the support substrate59. In addition, the height T1of the part445of the adhesive member44is smaller than the height T2(thickness) (refer toFIG. 7). Accordingly, it is possible to reduce or prevent the adhesive member44from adhering to the side electrode45provided in the force detecting element41or the terminal47provided on the base portion43, and to more stably dispose the force detecting element41in the recess portion433.

The plurality of pressurizing bolts51fixes the wall portion33and the wall portion22in a state of sandwiching the sensor device4(more specifically, a plurality of piezoelectric elements5) by the wall portion33of the first case member3and the wall portion22of the second case member2(refer toFIG. 3). Each of the pressurizing bolts51is inserted through the through-hole37of the wall portion33from the wall portion33side, and a male screw formed at the tip end portion of the pressurizing bolt51is screwed into the female screw hole26formed in the wall portion22. With the plurality of pressurizing bolts51, the inner wall surface331of the first case member3and the top surface231of the second case member2can sandwich and pressurize the force detecting element41via the package42of the sensor device4. In addition, by appropriately adjusting a fastening force of each of the pressurizing bolts51, the pressure of the lamination direction D1of the piezoelectric element5having a predetermined size can be applied as a pressure to the force detecting element41.

Although not being particular limited, as the configuration material of each of the pressurizing bolts51, for example, various metal materials can be employed. In addition, the positions of each of the pressurizing bolts51and the number of pressurizing bolts51are not limited to the positions and the number which are illustrated in the drawings, respectively. In addition, the number of the pressurizing bolts51may be one, three or more for one sensor device4, for example. In addition, the force detecting element41including the piezoelectric element5is sandwiched between the first case member3and the second case member2(particularly between the wall portion33and the wall portion22), but not being limited thereto, the force detecting element41maybe supported by any other configuration between the first case member3and the second case member2.

Analog Circuit Board

As illustrated inFIG. 2, the analog circuit board6is disposed in the space S, that is, between the first case member3and the second case member2. On the analog circuit board6, a through-hole61into which the protruding part23of the second case member2is inserted, and a through-hole62into which each of the pressurizing bolts51is inserted, are formed (FIGS. 2 and 3). The analog circuit board6is disposed on the center axis A1side with respect to the sensor device4in a state of being inserted into the part23. Accordingly, the analog circuit board6can be provided in the vicinity of the sensor device4, and the wiring length from the sensor device4can be shortened. Therefore, it is possible to contribute to simplifying the structure.

In addition, the analog circuit board6is electrically connected to the above-described sensor device4. Although not illustrated, the analog circuit board6includes a charge amplifier (not illustrated) for converting the electric charge Q (QX, QY, and QZ) output from the force detecting element41of the sensor device4respectively into the voltage V (VX, VY, and VZ). The charge amplifier can be configured to include, for example, an operational amplifier, a capacitor, and a switching element.

Digital Circuit Board

Although not illustrated, the digital circuit board can be provided on the second case member2, for example. The digital circuit board is electrically connected to the above-described analog circuit board6. Although not illustrated, the digital circuit board is provided with an external force detection circuit which detects (calculates) the external force based on the voltages VX, VY, and VZ from the analog circuit board6. The external force detection circuit calculates a translational force component Fx in the x-axis direction, a translational force component Fy in the y-axis direction, a translational force component Fz in the z-axis direction, a rotational force component Mx around the X-axis, a rotational force component My around the Y-axis, and a rotational force component Mz around the Z-axis. The external force detection circuit can be configured to include, for example, an AD converter and an arithmetic circuit, such as a CPU connected to the AD converter.

As described above, the force detection device1described above includes the top plate31(first base portion); the bottom plate21(second base portion); and the sensor device4which is an example of the sensor device according to the invention provided between the top plate31and the bottom plate21; and the external force detection circuit60that detects the external force based on the signal from the sensor device4. In the embodiment, as described above, the external force detection circuit60is configured of the analog circuit board6and the digital circuit board. According to the force detection device1, since the sensor device4is provided, it is possible to detect the external force with higher accuracy.

In addition, the sensor device4included in the force detection device1can be manufactured as follows.

Manufacturing Method of Sensor Device4

FIG. 10is a flowchart of a method of manufacturing the sensor device illustrated inFIG. 4.FIG. 11is a sectional view illustrating a process of applying the adhesive illustrated inFIG. 10.FIG. 12is a plan view illustrating a process of applying the adhesive illustrated inFIG. 10.FIG. 13is a sectional view illustrating a process of adhering the force detecting element illustrated inFIG. 10.FIG. 14is a sectional view illustrating a process of forming the connecting portion illustrated inFIG. 10.FIG. 15is a view illustrating a process of placing the lid body illustrated inFIG. 10.

As illustrated inFIG. 10, the manufacturing method of the sensor device4includes [1] a process of applying the adhesive440(step S11), [2] a process of adhering the force detecting element41(step S12), [3] a process of forming the connecting portion46(step S13), and [4] a process of placing the lid body49(step S14). Hereinafter, each process will be described in order.

First, as illustrated inFIGS. 11 and 12, for example, a paste-like adhesive440is applied onto the bottom member431of the base portion43. At this time, it is preferable that the adhesive440is radially applied, and it is more preferable to apply the adhesive440so as to extend from the center portion of the bottom member431to the terminal47. Specifically, as illustrated inFIG. 12, for example, it is preferable to apply the adhesive440in a cross shape. Accordingly, when the force detecting element41is placed on the adhesive440in a later step, it is possible to reduce generation of bubbles or residual bubbles between the force detecting element41and the base portion43. Therefore, it is possible to increase the adhering strength to the bottom surface4341of the force detecting element41. In addition, the uniformity of the thickness D of the formed adhesive member44can be enhanced.

In addition, for example, the adhesive440may be placed (applied) as a single mass at the center portion of the bottom member431, or may be disposed in a plurality of dot shapes. In addition, the adhesive440may be thinly and uniformly applied on the bottom surface4341, for example.

[2] Process of Adhering Force Detecting Element41(Step S12)

Next, the force detecting element41is placed on the adhesive440, is pressed in the direction of the arrow A4inFIG. 13, and cures the adhesive440.

Here, as the adhesive440, an adhesive (excluding a so-called instantaneous adhesive) having a certain degree of curing time at ordinary temperature (25° C.) or an adhesive cured by applying heat, light, electron beam or the like, is preferable. Accordingly, when the force detecting element41is placed on the adhesive440, the force detecting element41can temporarily adhere to the adhesive440. Therefore, it is easy to adjust the position of the force detecting element41in the recess portion433. In addition, the temporary adhesion refers to a state where the adhesion is in a state of being easily peelable and re-adhesion is possible.

In addition, when positioning is completed in a state of temporary adhesion, pressing in the direction of the arrow A4as described above is performed to cure the adhesive440. At this time, since the adhesive440has the filler442a,by pressing the force detecting element41, it is possible to easily control the distance between the force detecting element41and the bottom surface4341by the filler442athat functions as a gap material (refer toFIGS. 8 and 13). In addition, by pressing the force detecting element41, the adhesive440spreads from the center portion of the bottom member431to the outer edge portion of the bottom member431, and rises up between the force detecting element41and the side surface4342(refer toFIG. 7). Accordingly, as described above, a part of the adhesive440can be positioned between the force detecting element41and the side surface4342, and accordingly, the adhering strength of the force detecting element41to the base portion43can be further enhanced. In addition, it is preferable that the amount of the adhesive440is an amount that takes into consideration the gradually rising adhesive440.

[3] Process of Forming Connecting Portion46(Step S13)

Next, a material, such as Ag paste (a base material of the connecting portion46), is applied and cured between the side electrode45and the terminal47so as to adhere therebetween. Accordingly, the connecting portion46is formed as illustrated inFIG. 14.

Here, as described above, since the force detecting element41adheres to the base portion43by the adhesive member44, the relative position of the force detecting element41with respect to the base portion43is regulated. In other words, the adhesive member44functions as a position regulating member. Therefore, when a material, such as Ag paste, is applied so as to link the side electrode45and the terminal47in the process (step S13), since the position of the force detecting element41is not deviated with respect to the base portion43, a material, such as Ag paste, can be easily applied to a desired location, and workability is high.

Next, the lid body49is joined to the base portion43via the seal member48on the upper surface of the base portion43. Accordingly, as illustrated inFIG. 15, the sensor device4can be obtained.

As described above, the sensor device4can be manufactured. According to the method described above, since the position of the force detecting element41is regulated by the adhesive member44, the formation of the connecting portion46and the placement of the lid body49can be easily performed. Therefore, workability and productivity can be improved.

Next, a modification example of the sensor device4will be described.

FIG. 16is a sectional view illustrating a modification example of the sensor device illustrated inFIG. 4.

As illustrated inFIG. 16, the package42A of the sensor device4A does not include the lid body49of the sensor device4. In other words, the “lid body” which covers the opening of the recess portion433of the base portion43is omitted. In addition, the support substrate58of the force detecting element41directly abuts against the wall portion33of the first case member3. Even with the sensor device4A, similar to the above-described sensor device4, it is possible to enhance the stability of the position in the recess portion433of the force detecting element41including the adhesive member44, and to output a signal that corresponds to the external force with high accuracy.

Next, a reference example of the sensor device4will be described.

FIG. 17is a sectional view illustrating the reference example of the sensor device illustrated inFIG. 4.

As illustrated inFIG. 17, a sensor device4B does not include the package42of the sensor device4. In addition, the adhesive member44directly abuts against the wall portion22of the second case member2. Even with the sensor device4B, the force detecting element41can be stably installed on the wall portion22by the adhesive member44, and accordingly, a signal that corresponds to the external force can be output with high accuracy.

Next, the robot according to the invention will be described.

FIG. 18is a perspective view illustrating an example of the robot according to the invention.

The robot100illustrated inFIG. 18can perform work, such as feeding, removing, transporting and assembling, with respect to the target, such as precision equipment or components that configure the precision equipment. The robot100is a single-arm robot, and is a so-called six-axis vertical articulated robot. The robot100includes: a support base110; a robot arm10which is linked to the support base110to be freely rotatable; the force detection device1; and the end effector17.

The support base110is, for example, a part fixed to a floor, a wall, a ceiling, and a movable trolley. The robot arm10includes an arm11(first arm), an arm12(second arm), an arm13(third arm), an arm14(fourth arm), an arm15(fifth arm), and an arm16(sixth arm). The arms11to16are linked in this order from the base end side to the tip end side. Each of the arms11to16is rotatable with respect to an adjacent arm or the support base110.

The force detection device1is connected to the tip end of the arm16. The force detection device1detects the force (including moment) applied to the end effector17attached to the tip end of the force detection device1. The end effector17is a tool for performing work with respect to the target that is a work target of the robot100, and is configured with a hand having a function of gripping the target. In addition, the end effector17, a tool that corresponds to the work contents or the like of the robot100may be used, and not being limited to a hand, for example, a screw fastening tool for screw fastening, a fitting tool for fitting or the like may be employed.

In addition, although not being illustrated, the robot100includes a driving unit having a motor or the like that rotates one arm with respect to the other arm (or the support base110). In addition, although not illustrated, the robot100has an angle sensor for detecting the rotation angle of the rotating shaft of the motor.

The robot100has the support base110; the robot arm10(arm) connected to the support base110; and the above-described force detection device1. According to the robot100, the force detection device1is provided. Therefore, for example, by feeding back the external force detected by the force detection device1to a control unit (not illustrated) having a function of controlling the robot100, the robot100can perform the work more precisely. In addition, due to the external force detected by the force detection device1, the robot100can detect contact of the end effector17with an obstacle or the like. Therefore, it is possible to easily perform an obstacle avoiding operation, a target damage avoiding operation and the like, and the robot100can execute the work more safely.

Above, the sensor device, the force detection device, and the robot according to the invention is described based on the illustrated embodiments, but the invention is not limited thereto, and the configurations of each part may be replaced with other configurations having similar functions. In addition, any other configurations may be added to the invention.

In addition, the force detection device may be provided between the arm and the arm (attached member). In addition, the lamination direction of the piezoelectric element is not limited to that illustrated in the drawing. In addition, the pressurizing bolt may be provided as necessary, and may be omitted.

In addition, the robot according to the invention may be another robot, such as a scalar robot. In addition, although the number of arms of the robot100is six in the drawing, the invention is not limited thereto and may be 1 to 5 or 7 or more.

In addition, the robot according to the invention is not limited to a single arm robot as long as the robot has an arm, and may be another robot, such as a dual arm robot. In other words, the number of robot arms is not limited to one, and may be two or more.

In addition, the sensor device and the force detection device according to the invention can also be incorporated in devices other than the robot, and may be mounted on a moving object, such as an automobile.

The entire disclosure of Japanese Patent Application No. 2017-041359, filed Mar. 6, 2017, and No. 2018-007032, filed Jan. 19, 2018 are expressly incorporated by reference herein.