JP2015087290A - Force detection device, robot, electronic component conveyance device, electronic component inspection device, and component processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force detection device in which an output drift is reduced and which is downsized, and a robot, an electronic component conveyance device, an electronic component inspection device, and a component processing device using the force detection device.SOLUTION: A force detection device 1a includes: a first base 2; a first element 3a and a second element 3b for converting an electric charge outputted in accordance with external force into a voltage and detecting the external force from the voltage; and a second base 4 having at least the first element 3a and the second element 3b provided between the first base 2 and itself. The first element 3a and the second element 3b are disposed aslant against or perpendicular to the first base 2 and the second base 4, and have a polarization axis for the electric charge outputted in accordance with the external force, with a polarization axis Pβ1 of the electric charge outputted by the first element 3a and a polarization axis Pβ2 of the electric charge outputted by the second element 3b arranged so as to face the opposite direction each other.

Description

  The present invention relates to a force detection device, and a robot, an electronic component conveying device, an electronic component inspection device, and a component processing device using the force detection device.

  In recent years, industrial robots have been introduced into production facilities such as factories for the purpose of improving production efficiency. Such an industrial robot includes an arm that can be driven in one or a plurality of axial directions, a hand attached to the tip of the arm, and an end effector such as a component inspection device, a component transport device, and a component processing tool. It is possible to perform various operations such as component assembly operations, component processing operations, component inspection operations such as component inspection operations, and component transfer operations.

In such an industrial robot, a force detection device is provided between the arm and the end effector. This force detection device includes a piezoelectric element (charge output element) that outputs electric charge according to an applied external force, and a conversion circuit (converter) that converts electric charge output from the piezoelectric element into a voltage. An external force applied to the element can be detected. An industrial robot uses such a force detection device to detect an external force generated during a component manufacturing operation or a component transfer operation, and controls the arm and the end effector based on the detection result. As a result, the industrial robot can accurately execute the parts manufacturing work or the parts transporting work.
As such a force detection device, a crystal type piezoelectric sensor using a crystal as a piezoelectric element is widely used. Crystal type piezoelectric sensors are widely used in industrial robots because they have excellent characteristics such as a wide dynamic range, high rigidity, high natural frequency, and high load resistance.

However, in such a crystal type piezoelectric element, since the electric charge output from the crystal is weak, the influence of output drift due to the leakage current of the conversion circuit cannot be ignored. Various methods for reducing the output drift have been studied. For example, Patent Literature 1 discloses a crystal piezoelectric sensor including a reverse bias circuit using a diode having current characteristics similar to the leakage current characteristics of a conversion circuit. The crystal-type piezoelectric sensor disclosed in Patent Document 1 reduces output drift by supplying a correction current from a diode that has substantially the same magnitude as the leakage current of the conversion circuit and has an opposite flow direction.
However, when a reverse bias circuit is used as in the crystal type piezoelectric sensor of Patent Document 1, additional components such as a diode are required, and the mounting area is enlarged, so that downsizing is difficult. In addition, there is a problem that component accuracy management for supplying a desired correction current is required.

Japanese Patent Laid-Open No. 9-72757

  The present invention has been made in view of the above circumstances, the output drift due to the leakage current of the conversion circuit is reduced, and the force detection device is miniaturized, and the robot and electronic component using the force detection device It is an object of the present invention to provide a transport device, an electronic component inspection device, and a component processing device.

Such an object is achieved by the following invention.
<Application example 1>
The force detection device according to the present invention includes a first base, a first element and a second element that detect the external force from the voltage by converting a charge output according to an external force into a voltage, and the first A second base provided with at least the first element and the second element between the first base,
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged to face in opposite directions.

  Thereby, although the sign of the output drift included in the voltage output from the first element matches the sign of the output drift included in the voltage output from the second element, the output drift is output from the first element. Included in the voltage, the sign of the voltage component (true value) proportional to the accumulated amount of charge output from the sensor according to the external force, and the voltage output from the second element, and included in the sensor according to the external force The sign of the voltage component (true value) that is proportional to the amount of accumulated voltage output from can be reversed. Therefore, by calculating the external force using the voltage output from the first element and the voltage output from the second element, it is included in the voltages output from the first element and the second element. External force can be detected while reducing output drift. As a result, the detection accuracy and detection resolution of the force detection device can be improved. Furthermore, since a circuit for reducing output drift such as a reverse bias circuit is unnecessary, the force detection device can be reduced in size.

<Application example 2>
In the force detection device according to the present invention, it is preferable that the force detection device takes a difference between the voltages output from the first element and the second element.
Thereby, the detection error resulting from output drift can be reduced.
<Application example 3>
In the force detection device according to the present invention, in the first element and the second element, the polarization axis of the first element and the polarization axis of the second element are on the same axis. It is preferable.
As a result, the external force can be detected while further reducing the output drift.

<Application example 4>
In the force detection device according to the present invention, the first element and the second element are:
It is configured by laminating a plurality of ground electrode layers grounded to the ground and three sensors having a polarization axis of charge output according to the external force, and the polarization axes of the sensors are orthogonal to each other. It is preferable.
Thereby, the force detection device can detect six-axis forces (translational force components in the x, y, and z axis directions and rotational force components around the x, y, and z axes).

<Application example 5>
In the force detection device according to the present invention, when the stacking direction of the sensors is a γ-axis direction, and the directions orthogonal to the γ-axis direction and orthogonal to each other are an α-axis direction and a β-axis direction,
One of the sensors is an α-axis sensor that outputs the electric charge according to the external force in the α-axis direction,
One of the sensors is a β-axis sensor that outputs the electric charge according to the external force in the β-axis direction,
One of the sensors is preferably a γ-axis sensor that outputs the electric charge according to the external force in the γ-axis direction.
Thereby, the sensor can output electric charge according to the triaxial force (translational force component in the x, y, and z axis directions).

<Application example 6>
The force detection device according to the present invention includes two first elements and two second elements,
The direction of the polarization axis of one of the first elements and one of the second elements is the direction of the polarization axis of the other first element and the other of the second element. Facing the direction opposite to the direction of the polarization axis of
The direction of the polarization axis of the γ-axis sensor of the one first element and the one second element is the γ-axis sensor of the other first element and the other second element. It is preferable to face the direction opposite to the direction of the polarization axis.
Thereby, based on the voltage output from the 1st element and the 2nd element, 6 axial force can be detected, reducing output drift.

<Application example 7>
In the force detection device according to the present invention, the sensor is provided with a first piezoelectric layer having a first crystal axis and a first piezoelectric layer provided opposite to the first piezoelectric layer and having a second crystal axis. Two piezoelectric layers, and an output electrode layer provided between the first piezoelectric layer and the second piezoelectric layer,
It is preferable that the direction of the first crystal axis of the first piezoelectric layer is opposite to the direction of the second crystal axis of the second piezoelectric layer.
Thereby, the electric charge output from an output electrode layer can be increased.

<Application example 8>
In the force detection device according to the present invention, it is preferable that the first piezoelectric layer and the second piezoelectric layer are made of quartz.
Accordingly, a piezoelectric layer having excellent characteristics such as a wide dynamic range, high rigidity, high natural frequency, and high load resistance can be configured.
<Application example 9>
In the force detection device according to the present invention, it is preferable that the elements are arranged at equiangular intervals in the circumferential direction of the first base portion or the second base portion.
Thereby, an external force can be detected without deviation.

<Application example 10>
The robot according to the present invention includes a plurality of arms, and is provided on at least one arm connection body formed by rotatably connecting the adjacent arms of the plurality of arms, and on a distal end side of the arm connection body. An end effector, and a force detection device that is provided between the arm coupling body and the end effector and detects an external force applied to the end effector,
The force detection device includes a first base, a first element and a second element that detect the external force from the voltage by converting a charge output according to an external force into a voltage, and the first base. A second base portion provided with at least the first element and the second element,
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged to face in opposite directions.

  Thereby, the external force detected by the force detection device can be fed back, and the operation can be executed more precisely. Further, the contact of the end effector with the obstacle can be detected by the external force detected by the force detection device. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like, which are difficult with conventional position control, can be easily performed, and the work can be executed more safely. Furthermore, since a circuit for reducing output drift such as a reverse bias circuit is unnecessary, the force detection device can be reduced in size. Therefore, the robot can be reduced in size.

<Application example 11>
An electronic component transport device according to the present invention includes a gripping unit that grips an electronic component, and a force detection device that detects an external force applied to the gripping unit,
The force detection device includes a first base, a first element and a second element that detect the external force from the voltage by converting a charge output according to an external force into a voltage, and the first base. A second base portion provided with at least the first element and the second element,
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged to face in opposite directions.

  Thereby, the external force detected by the force detection device can be fed back, and the operation can be executed more precisely. In addition, contact of the grip portion with an obstacle can be detected by the external force detected by the force detection device. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like, which are difficult with conventional position control, can be easily performed, and the electronic component transport operation can be executed more safely. Furthermore, since a circuit for reducing output drift such as a reverse bias circuit is unnecessary, the force detection device can be reduced in size. Therefore, the electronic component transport device can be reduced in size.

<Application Example 12>
An electronic component inspection apparatus according to the present invention includes a gripping unit that grips an electronic component, an inspection unit that inspects the electronic component, and a force detection device that detects an external force applied to the gripping unit,
The force detection device includes a first base, a first element and a second element that detect the external force from the voltage by converting a charge output according to an external force into a voltage, and the first base. A second base portion provided with at least the first element and the second element,
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged to face in opposite directions.

  Thereby, the external force detected by the force detection device can be fed back, and the operation can be executed more precisely. In addition, contact of the grip portion with an obstacle can be detected by the external force detected by the force detection device. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that are difficult with conventional position control can be easily performed, and an electronic component inspection operation can be performed more safely. Furthermore, since a circuit for reducing output drift such as a reverse bias circuit is unnecessary, the force detection device can be reduced in size. Therefore, the electronic component inspection apparatus can be reduced in size.

<Application Example 13>
A component processing apparatus according to the present invention includes a tool displacement unit that mounts a tool and displaces the tool, and a force detection device that detects an external force applied to the tool,
The force detection device includes a first base, a first element and a second element that detect the external force from the voltage by converting a charge output according to an external force into a voltage, and the first base. A second base portion provided with at least the first element and the second element,
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged to face in opposite directions.

  Thereby, by feeding back the external force detected by the force detection device, the component processing device can execute the component processing operation more precisely. Further, contact of the tool with an obstacle can be detected by an external force detected by the force detection device. Therefore, an emergency stop can be performed when an obstacle or the like comes into contact with the tool, and the component processing apparatus can execute a safer component processing operation. Furthermore, since a circuit for reducing output drift such as a reverse bias circuit is unnecessary, the force detection device can be reduced in size. Therefore, the component processing apparatus can be reduced in size.

FIG. 1 is a perspective view, a plan view, and a cross-sectional view schematically showing a first embodiment of a force detection device according to the present invention. It is a circuit diagram which shows roughly the force detection apparatus shown in FIG. It is sectional drawing which shows schematically the electric charge output element of the force detection apparatus shown in FIG. It is the perspective view and sectional drawing which show schematically 2nd Embodiment of the force detection apparatus which concerns on this invention. It is the perspective view, top view, and sectional drawing which show schematically 3rd Embodiment of the force detection apparatus which concerns on this invention. FIG. 6 is a circuit diagram schematically showing the force detection device shown in FIG. 5. It is sectional drawing which shows schematically the electric charge output element of the force detection apparatus shown in FIG. It is a figure which shows an example of the single arm robot using the force detection apparatus which concerns on this invention. It is a figure which shows an example of the multi-arm robot using the force detection apparatus which concerns on this invention. It is a figure which shows one example of the electronic component inspection apparatus and electronic component conveyance apparatus using the force detection apparatus which concerns on this invention. It is a figure which shows one example of the electronic component conveying apparatus using the force detection apparatus which concerns on this invention. It is a figure which shows one example of the component processing apparatus using the force detection apparatus which concerns on this invention. It is a figure which shows an example of the moving body using the force detection apparatus which concerns on this invention.

Hereinafter, a force detection device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<First Embodiment>
FIG. 1A is a perspective view schematically showing a first embodiment of a force detection device according to the present invention. FIG.1 (b) is a top view which shows roughly 1st Embodiment of the force detection apparatus based on this invention. FIG. 1C is a cross-sectional view taken along line A shown in FIG. In FIG. 1B, some components are omitted for explanation. FIG. 2 is a circuit diagram schematically showing the force detection device shown in FIG. FIG. 3 is a cross-sectional view schematically showing the charge output element of the force detection device shown in FIG.

  The force detection device 1a shown in FIG. 1 has a function of detecting a shearing force (external force on the x-axis and y-axis in FIG. 1) and a compression / tensile force (external force on the z-axis in FIG. 1). The force detection device 1a includes a first base (base plate) 2 and force detection elements 3a and 3b (first elements 3a and 3a) that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage. Between the 2nd element 3b) and the 1st base 2, it has the 2nd base (cover plate) 4 which provides the 1st element 3a and the 2nd element 3b at least.

  As shown in FIG. 1, the 1st base 2 and the 2nd base 4 are provided so that it may oppose. The elements 3a and 3b are sandwiched (provided) between the first base 2 and the second base 4 in an inclined state with respect to the first base 2, and output a voltage according to an external force. The voltage output from each of the force detection elements 3a and 3b is input to the external force detection circuit 5 (not shown in FIG. 1, refer to FIG. 2), and the external force is detected. In FIG. 2, the external force detection circuit 5 is expressed as a component different from the elements 3a and 3b, but the present invention is not limited to this. In the force detection element 1a of the present invention, the elements 3a and 3b may have the external force detection circuit 5 as a component.

<First base>
The first base 2 shown in FIG. 1 has a function of transmitting an external force applied to the force detection device 1a to the force detection elements 3a and 3b. The first base portion 2 is a flat plate-like member having a substantially circular shape in plan view. The first base 2 is made of a material having a relatively high rigidity, and is not deformed by an external force applied to the force detection device 1a. Therefore, the external force applied to the force detection device 1a can be transmitted to the force detection elements 3a and 3b. Moreover, the 1st base 2 has the 1st inclination part 21 provided in the outer periphery on the surface of the side facing the 2nd base 4 of the 1st base 2. As shown in FIG.

  The 1st inclination part 21 has a function which mounts force detection element 3a, 3b fixedly on the inclined surface. The first inclined portion 21 has a substantially cylindrical shape in plan view. As shown in FIG. 1C, the first inclined portion 21 is provided so that the inclined surface faces the outside of the first base portion 2, and the inclined surface of the first inclined portion 21 is the first inclined portion 21. It is inclined with respect to the base 2 at an angle φ. The angle φ is not particularly limited, and is arbitrarily set within a range of 0 <φ <π / 2. In addition, the 1st inclination part 21 is comprised with the material which has comparatively high rigidity similarly to the 1st base 2, and does not deform | transform by the external force applied with respect to the force detection apparatus 1a. The constituent material of the first base 2 and the constituent material of the first inclined portion 21 may be the same or different.

  On the inclined surface of the first inclined portion 21, force detecting elements 3a and 3b are fixedly arranged. That is, the force detection elements 3 a and 3 b of the present embodiment are arranged in an inclined state with respect to the first base 2. In this case, as will be described later, the external force applied to the force detection device 1a can be detected by being decomposed into a plurality of orthogonal directions (x, y, z directions in FIG. 1A). .

  In the illustrated configuration, the first inclined portion 21 is a substantially cylindrical member in plan view, but the present invention is not limited to this. The first inclined portion 21 may have any configuration as long as the force detecting elements 3a and 3b can be fixedly placed with the force detecting elements 3a and 3b inclined with respect to the first base portion 2. For example, a plurality (two in this embodiment) of discontinuous first inclined portions 21 are provided on the first base portion 2, and force detection is performed on the inclined surface of each first inclined portion 21. Elements 3a and 3b may be fixedly arranged. Moreover, the 1st base 2 and the 1st inclination part 21 may each be formed as a separate member, and may be formed integrally.

<Second base>
The second base 4 shown in FIG. 1 is provided to face the first base 2, and has a function of transmitting an external force applied to the force detection device 1a to the force detection elements 3a and 3b. Similar to the first base 2, the second base 4 is a flat plate member having a substantially circular shape in plan view. The second base 4 is made of a material having a relatively high rigidity, and is not deformed by an external force applied to the force detection device 1a. Therefore, the external force applied to the force detection device 1a can be transmitted to the force detection elements 3a and 3b. Further, the second base portion 4 has a second inclined portion 41 provided on the surface of the second base portion 4 on the side facing the first base portion 2 so as to correspond to (along) the outer periphery thereof. .

The second inclined portion 41 has a function of holding (holding) the force detection elements 3 a and 3 b together with the first inclined portion 21 provided on the first base portion 2. The second inclined portion 41 is provided at a position corresponding to the first inclined portion 21 provided on the first base 2, and has a substantially cylindrical shape in plan view. The second inclined portion 41 is provided so that the inclined surface faces the center side of the second base portion 4, and the inclined surface of the second inclined portion 41 is inclined at an angle φ with respect to the second base portion 4. doing. Therefore, when the second base 4 is disposed so as to face the first base 2, the inclined surface of the second inclined portion 41 provided on the second base 4 and the first provided on the first base 2. The inclined surfaces of the inclined portions 21 are parallel to each other. Therefore, the force detection elements 3 a and 3 b that are fixedly arranged on the inclined surface of the first inclined portion 21 are arranged between the inclined surface of the first inclined portion 21 and the inclined surface of the second inclined portion 42. It can be held (held).
In addition, the 2nd inclination part 41 is comprised with the material which has comparatively high rigidity similarly to the 2nd base 4, and does not deform | transform by the external force applied with respect to the force detection apparatus 1a. The constituent material of the second base portion 4 and the constituent material of the second inclined portion 41 may be the same or different.

  In the illustrated configuration, the second inclined portion 41 is a substantially cylindrical member in plan view, but the present invention is not limited to this. If the second inclined portion 41 can sandwich (hold) the force detecting elements 3a and 3b fixedly arranged on the inclined surface of the first inclined portion 21 together with the first inclined portion 21, Any configuration is possible. For example, a plurality of (two in this embodiment) discontinuous second inclined portions 41 may be provided at positions corresponding to the force detection elements 3a and 3b. Moreover, the 2nd base 4 and the 2nd inclination part 41 may each be formed as a separate member, and may be formed integrally.

<Force detection element (element)>
The force detection elements 3a and 3b (first element 3a and second element 3b) shown in FIG. 1 have a function of outputting a voltage V in accordance with an applied shear force.
As shown in FIG. 2, the force detection elements 3 a and 3 b convert the charge output element 31 that outputs the charge Q according to the applied shear force and the charge Q output from the charge output element 31 into a voltage V. And a conversion circuit 32.

<Charge output element>
The charge output element 31 shown in FIG. 3 has a function of outputting a charge Q in accordance with an external force (shearing force) parallel to the β axis in FIG. The charge output element 31 includes two ground electrode layers 310 and a β-axis sensor 320 provided between the two ground electrode layers 310. In FIG. 3, the lamination direction of the ground electrode layer 310 and the β-axis sensor 320 is the γ-axis direction, and the directions orthogonal to the γ-axis direction and orthogonal to each other are the α-axis direction and the β-axis direction, respectively.

In the illustrated configuration, the ground electrode layer 310 and the β-axis sensor 320 all have the same width (length in the left-right direction in the drawing), but the present invention is not limited to this. For example, the width of the ground electrode layer 310 may be wider than the width of the β-axis sensor 320, or vice versa.
The ground electrode layer 310 is an electrode grounded to the ground (reference potential point). Although the material which comprises the ground electrode layer 310 is not specifically limited, For example, gold | metal | money, chromium, titanium, aluminum, copper, iron, nickel, or an alloy containing these is preferable.

  The β-axis sensor 320 has a function of outputting a charge Q according to an external force (shearing force) parallel to the β-axis. The β-axis sensor 320 is configured to output a positive charge according to an external force along the positive direction of the β axis and to output a negative charge according to an external force applied along the negative direction of the β axis. Yes. In other words, the β-axis sensor 320 uses the polarization axis (detection direction) Pβ of the electric charge output according to the external force applied along the β-axis direction (that is, the polarization axis Pβ facing the positive direction of the β-axis). Have.

  The β-axis sensor 320 is provided so as to face the first piezoelectric layer 321 having the first crystal axis CA1 and the first piezoelectric layer 321 and has the second piezoelectric axis having the second crystal axis CA2. A body layer 323 and an output electrode layer 322 that outputs a charge Q are provided between the first piezoelectric layer 321 and the second piezoelectric layer 323. Further, the stacking order of the layers constituting the β-axis sensor 320 is the order of the first piezoelectric layer 321, the output electrode layer 322, and the second piezoelectric layer 323 from the lower side in FIG.

  The first piezoelectric layer 321 is composed of a piezoelectric body having a first crystal axis CA1 oriented in the negative direction of the β axis. When an external force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 321, electric charges are induced in the first piezoelectric layer 321 by the piezoelectric effect. As a result, positive charges are collected near the surface of the first piezoelectric layer 321 on the output electrode layer 322 side, and negative charges are collected near the surface of the first piezoelectric layer 321 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 321, negative charges are generated near the surface of the first piezoelectric layer 321 on the output electrode layer 322 side. As a result, positive charges are collected near the surface of the first piezoelectric layer 321 on the ground electrode layer 310 side.

  The second piezoelectric layer 323 is composed of a piezoelectric body having a second crystal axis CA2 oriented in the positive direction of the β axis. When an external force along the positive direction of the β axis is applied to the surface of the second piezoelectric layer 323, electric charges are induced in the second piezoelectric layer 323 due to the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the second piezoelectric layer 323 on the output electrode layer 322 side, and negative charges are collected in the vicinity of the surface of the second piezoelectric layer 323 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the second piezoelectric layer 323, negative charges are generated near the surface of the second piezoelectric layer 323 on the output electrode layer 322 side. The positive charges are collected near the surface of the second piezoelectric layer 323 on the ground electrode layer 310 side.

  Thus, the direction of the first crystal axis CA1 of the first piezoelectric layer 321 is opposite to the direction of the second crystal axis CA2 of the second piezoelectric layer 323. As a result, compared to the case where the β-axis sensor 320 is configured by only one of the first piezoelectric layer 321 and the second piezoelectric layer 323 and the output electrode layer 322, the output electrode layer 322 is closer to the output electrode layer 322. The collected positive or negative charge can be increased. As a result, the charge Q output from the output electrode layer 322 can be increased.

The constituent materials of the first piezoelectric layer 321 and the second piezoelectric layer 323 are quartz, topaz, barium titanate, lead titanate, lead zirconate titanate (PZT: Pb (Zr, Ti) O ₃ ), lithium niobate, lithium tantalate and the like. Of these, quartz is particularly preferable. This is because the piezoelectric layer made of quartz has excellent characteristics such as a wide dynamic range, high rigidity, high natural frequency, and high load resistance. In addition, like the first piezoelectric layer 321 and the second piezoelectric layer 323, piezoelectric layers that generate an electric charge with respect to an external force (shearing force) along the surface direction of the layers are configured by Y-cut quartz. be able to.

The output electrode layer 322 has a function of outputting positive charges or negative charges generated in the first piezoelectric layer 321 and the second piezoelectric layer 323 as charges Q. As described above, when an external force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 321 or the surface of the second piezoelectric layer 323, a positive charge is present in the vicinity of the output electrode layer 322. Gather. As a result, a positive charge Q is output from the output electrode layer 322. On the other hand, when an external force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 321 or the surface of the second piezoelectric layer 323, negative charges are collected in the vicinity of the output electrode layer 322. As a result, a negative charge Q is output from the output electrode layer 322.
As described above, the charge output element 31 includes the ground electrode layer 310 and the β-axis sensor 320 described above, and outputs a charge Q according to an external force (shearing force) parallel to the β-axis in FIG. be able to.

  In addition, although the example which has the function to output the electric charge Q according to the external force (shearing force) parallel to the β axis has been described as the charge output element 31, the present invention is not limited to this. By using the first piezoelectric layer 321 having a different orientation direction of the first crystal axis CA1 and the second piezoelectric layer 323 having a different orientation direction of the second crystal axis CA2, an external force (shearing) parallel to the α axis can be obtained. It is possible to configure the charge output element 31 that outputs the charge Q according to the force). Such a case is also within the scope of the present invention.

<Conversion circuit>
The conversion circuit 32 has a function of converting the charge Q output from the charge output element 31 into a voltage V. The conversion circuit 32 includes an operational amplifier 33, a capacitor 34, and a switching element 35. The first input terminal (minus input) of the operational amplifier 33 is connected to the output electrode layer 322 of the charge output element 31, and the second input terminal (plus input) of the operational amplifier 33 is grounded to the ground (reference potential point). ing. The output terminal of the operational amplifier 33 is connected to the external force detection circuit 5. The capacitor 34 is connected between the first input terminal and the output terminal of the operational amplifier 33. The switching element 35 is connected between the first input terminal and the output terminal of the operational amplifier 33 and is connected in parallel with the capacitor 34. The switching element 35 is connected to a drive circuit (not shown), and performs a switching operation in accordance with an on / off signal from the drive circuit.

  When the switching element 35 is off, the charge Q output from the charge output element 31 is stored in the capacitor 34 having the electrostatic capacity C1 and is output to the external force detection circuit 5 as the voltage V. Next, when the switching element 35 is turned on, both terminals of the capacitor 34 are short-circuited. As a result, the electric charge Q stored in the capacitor 34 is discharged to 0 coulomb, and the voltage V output to the external force detection circuit 5 becomes 0 volt. When the switching element 35 is turned on, the conversion circuit 32 is reset.

  The switching element 35 is a semiconductor switching element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Since the semiconductor switching element is smaller and lighter than the mechanical switch, it is advantageous for reducing the size and weight of the force detection device 1a. Hereinafter, a case where a MOSFET is used as the switching element 35 will be described as a representative example.

  The switching element 35 has a drain electrode, a source electrode, and a gate electrode. One of the drain electrode and the source electrode of the switching element 35 is connected to the first input terminal of the operational amplifier 33, and the other of the drain electrode and the source electrode is connected to the output terminal of the operational amplifier 33. The gate electrode of the switching element 35 is connected to a drive circuit (not shown).

The voltage V output from the ideal conversion circuit 32 is proportional to the accumulation amount of the charge Q output from the charge output element 31. However, in the actual conversion circuit 32, a leak current that flows from the switching element 35 to the capacitor 34 is generated. Such a leakage current becomes an output drift D included in the voltage V. Therefore, if the voltage component (true value) proportional to the amount of charge Q accumulated is Vt, the output voltage V is V = Vt + D.
Since the output drift D becomes an error with respect to the measurement result, there has been a problem that the detection accuracy and the detection resolution of the force detection elements 3a and 3b are reduced by the leak current (output drift D). In addition, since the leak current is accumulated in proportion to the measurement (driving) time, there is a problem that the measurement time of the force detection device 1a cannot be lengthened.

  Such a leakage current is caused by a semiconductor structure such as insufficient insulation of the gate insulating film, miniaturization of process rules, and variations in impurity concentration in the semiconductor, and a use environment such as temperature and humidity. Since the leakage current due to the semiconductor structure is a unique value for each switching element, it can be compensated relatively easily by measuring the leakage current due to the semiconductor structure in advance. However, since the leakage current resulting from the use environment varies depending on the use environment (situation), it is difficult to compensate. The force detection device 1a according to the present invention detects an external force based on the force detection elements (elements) 3a and 3b forming a pair of elements and the voltages V1 and V2 output from the force detection elements 3a and 3b, respectively. By using the circuit 5, it is possible to reduce the influence (output drift D) due to the leakage current.

  Next, with reference to FIG. 1, the positional relationship between the force detection elements 3a and 3b forming the element pair will be described in detail. In addition, in FIG.1 (b), the 2nd base 4 is abbreviate | omitted for description. In FIG. 1B, the left-right direction is the x-axis direction, the direction orthogonal to the x-axis direction, that is, the vertical direction is the y-axis direction, and the direction orthogonal to the x-axis and y-axis is the z-axis direction. Furthermore, a straight line passing through the centers of the force detection elements 3a and 3b in FIG. FIG.1 (c) is sectional drawing along the A line of FIG.1 (b).

The force detection element 3a has the polarization axis Pβ1 along the β axis described above, and outputs the voltage V1 according to the external force (shearing force) along the β axis. Similarly, the force detection element 3b has the polarization axis Pβ2 along the β axis described above, and outputs the voltage V2 according to the external force (shearing force) along the β axis.
The force detection elements 3a and 3b are each fixedly arranged on the inclined surface of the first inclined portion 21, and are sandwiched (held) between the first inclined portion 21 and the second inclined portion 41. . That is, the force detection elements 3 a and 3 b are provided between the first base portion 2 and the second base portion 4 in a state inclined with respect to the first base portion 2 at an angle φ.

  The polarization axis Pβ1 of the force detection element 3a has an angle θ1 in the horizontal direction (xy plane). Similarly, the polarization axis Pβ2 of the force detection element 3b has an angle θ2 in the horizontal direction. The angles θ1 and θ2 are angles from the x axis of the reference coordinate system (x axis, y axis, z axis) in FIG. Furthermore, as shown in FIG. 1C, the polarization axes Pβ1 and Pβ2 of the force detection elements 3a and 3b each have an angle φ in the vertical direction (a plane including the z-axis direction). Note that the angle φ is an angle with respect to the xy plane of the reference coordinate system in FIG.

  As shown in FIG. 1B, the force detection elements 3a and 3b have a horizontal component (x, y component) of the polarization axis Pβ1 of the force detection element 3a and a horizontal component of the polarization axis Pβ2 of the force detection element 3b. It arrange | positions so that it may face the mutually opposite direction. “Directing in opposite directions” here means that the horizontal component of the polarization axis Pβ1 and the horizontal component of the polarization axis Pβ2 face each other as shown in FIG. 1B, that is, the angles θ1 and θ2 are θ1 = θ2. It is not limited to satisfying the relationship. When at least the horizontal component of the polarization axis Pβ1 and the horizontal component of the polarization axis Pβ2 are respectively decomposed into a vector component in the x-axis direction and a vector component in the y-axis direction, the vector component in the x-axis direction of the polarization axis Pβ1 The vector component in the x-axis direction of the polarization axis Pβ2 may be in the opposite direction, or the vector component in the y-axis direction of the polarization axis Pβ1 and the vector component in the y-axis direction of the polarization axis Pβ2 may be in the opposite directions.

Further, the force detection elements 3a and 3b have the vector component in the x-axis direction of the polarization axis Pβ1 and the vector component in the x-axis direction of the polarization axis Pβ2 reversed, and the vector component in the y-axis direction of the polarization axis Pβ1 and the polarization axis. It is preferable to arrange the vector components of Pβ2 in the y-axis direction to be opposite, that is, satisfy the relationship of | θ1-θ2 | <π / 2. Thereby, shear forces Fx and Fy described later can be detected. In the following description, the case where the force detection elements 3a and 3b are arranged so as to satisfy the relationship | θ1-θ2 | <π / 2 will be described as a representative.
The force detection elements 3a and 3b are more preferably arranged so that the horizontal component of the polarization axis Pβ1 and the horizontal component of the polarization axis Pβ2 face each other, that is, satisfy the relationship θ1 = θ2. Thereby, the external force detection circuit 5 to be described later can detect the shear forces Fx and Fy while further reducing the output drift D.

  If the horizontal component of the polarization axis Pβ1 of the force detection element 3a and the horizontal component of the polarization axis Pβ2 of the force detection element 3b are arranged so as to face in opposite directions, the arrangement of the force detection elements 3a and 3b is particularly great. Although not limited, as shown in FIG. 1B, it is preferable that the force detection element 3a and the force detection element 3b are arranged on the same axis (A line). Thereby, the shear force (external force along the x-axis and y-axis in the figure) applied to the first base 2 or the second base 4 can be detected without deviation.

Further, the horizontal component of the polarization axis Pβ1 of the force detection element 3a and the horizontal component of the polarization axis Pβ2 of the force detection element 3b in FIG. 1B are directed to the outside (centrifugal direction) of the first base 2, but this The invention is not limited to this. That is, if the horizontal component of the polarization axis Pβ1 of the force detection element 3a and the horizontal component of the polarization axis Pβ2 of the force detection element 3b are arranged so as to face in opposite directions, the horizontal axis of the polarization axis Pβ1 of the force detection element 3a. The horizontal component of the component and the polarization axis Pβ2 of the force detection element 3b may face the center direction (centrecent direction) of the first base 2.
The voltage component (true value) proportional to the accumulated amount of the charge Q1 output from the charge output element 31 of the force detection element 3a is Vt1, and the accumulated amount of the charge Q2 output from the charge output element 31 of the force detection element 3b. Assuming that the voltage component (true value) proportional to is Vt2, the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b are as follows.

  The switching element 35 of the force detection element 3a and the switching element 35 of the force detection element 3b are equivalent semiconductor switching elements, and their leakage currents are substantially equal. Therefore, the output drift D included in the voltage V1 is substantially equal to the output drift D included in the voltage V2. Here, “substantially equal” means that when a difference between two values to be compared is taken, the difference is negligibly small compared to the original value.

  In addition, the force detection elements 3a and 3b are arranged so that the horizontal component of the polarization axis Pβ1 of the force detection element 3a and the horizontal component of the polarization axis Pβ2 of the force detection element 3b are directed in opposite directions. The horizontal component of the voltage component Vt1 included in V1 (ie, Vt1 × cos (φ)) and the sign of the horizontal component of the voltage component Vt2 included in voltage V2 (ie, Vt2 × cos (φ)) do not match. For example, if the sign of the horizontal component of the voltage component Vt1 is positive, the sign of the horizontal component of the voltage component Vt2 is negative. Similarly, if the sign of the horizontal component of the voltage component Vt1 is negative, the sign of the horizontal component of the voltage component Vt2 is positive. Therefore, the horizontal component of the voltage V1 output from the force detection element 3a (ie, V1 × cos (φ)) and the horizontal component of the voltage V2 output from the force detection element 3b (ie, V2 × cos (φ)). When the difference is taken, the absolute value of the difference between the horizontal component of the voltage component Vt1 and the horizontal component of the voltage component Vt2 does not decrease.

  On the other hand, since the output drift D included in the horizontal component of the voltage V1 and the output drift D included in the horizontal component of the voltage V2 do not depend on the directions of the polarization axes Pβ1 and Pβ2, the output drift included in the horizontal component of the voltage V1. The sign of D coincides with the sign of output drift D included in the horizontal component of voltage V2. Therefore, when the difference between the horizontal component of the voltage V1 output from the force detection element 3a and the horizontal component of the voltage V2 output from the force detection element 3b is taken, the output drift D included in the horizontal component of the voltage V1 is The absolute value of the difference from the output drift D included in the horizontal component of the voltage V2 decreases.

<External force detection circuit>
The external force detection circuit 5 is based on the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b, and the shear force applied to the force detection device 1a (x-axis, y in the figure). (External force along the axis) and compression / tensile force Fz.
The external force detection circuit 5 can detect the shear forces Fx and Fy applied to the force detection device 1a by taking the difference between the voltages V1 and V2 as follows. Moreover, since the force detection elements 3a and 3b are provided to be inclined with respect to the first base 2, the external force detection circuit 5 is compressed / tensile applied to the force detection device 1a based on the voltages V1 and V2. The force Fz can be detected.

Thus, when the difference between the horizontal component of the voltage V1 output from the force detection element 3a and the horizontal component of the voltage V2 output from the force detection element 3b is taken, the horizontal component of the voltage component Vt1 and the voltage component Vt2 The absolute value of the horizontal component difference does not decrease, and the absolute value of the output drift D decreases. Therefore, the output drift D in the shear forces Fx and Fy can be reduced. As a result, in the shear forces Fx and Fy, the detection error caused by the leak current (output drift D) is relatively small, and the detection accuracy and the detection resolution for the shear forces Fx and Fy of the force detection device 1a can be improved. it can. Further, since the above-described method for reducing the output drift D is effective even when the measurement time is increased, the measurement time of the force detection device 1a can be increased.
Further, when the angles θ1 and θ2 satisfy θ1 = θ2, that is, when the force detection elements 3a and 3b are arranged so that the horizontal component of the polarization axis Pβ1 and the horizontal component of the polarization axis Pβ2 face each other, The calculation formula is simplified and becomes as follows.

In this case, the output drift D in the shear forces Fx and Fy can be removed (further reduced). As a result, the detection accuracy and detection resolution for the shear forces Fx and Fy of the force detection device 1a can be further improved. Moreover, the measurement time of the force detection device 1a can be further increased.
As described above, the force detection device 1a according to the present invention is arranged so that the horizontal component of the polarization axis Pβ1 of the force detection element 3a and the horizontal component of the polarization axis Pβ2 of the force detection element 3b face in opposite directions. In addition to the force detection device 1a, the difference between the horizontal components of the force detection elements 3a and 3b and the voltage V1 output from the force detection element 3a and the horizontal component of the voltage V2 output from the force detection element 3b is obtained. Since the external force detection circuit 5 for detecting the generated shear forces Fx and Fy is provided, the output drift D caused by the leakage current of the switching element 35 of the conversion circuit 32 can be reduced. As a result, the detection accuracy and the detection resolution for the shear forces Fx and Fy of the force detection device 1a can be improved. Further, since the above-described method for reducing the output drift D is effective even when the measurement time is increased, the measurement time of the force detection device 1a can be increased. Furthermore, in the force detection device 1a according to the present invention, a circuit for reducing the output drift D such as a reverse bias circuit is unnecessary, so that the force detection device 1a can be reduced in size.

Further, since the force detection elements 3a and 3b are provided to be inclined with respect to the first base 2, the vertical component of the voltage V1 output from the force detection element 3a (that is, V1 × sin (φ)) and The compression / tensile force Fz applied to the force detection device 1a can be detected based on the vertical component of the voltage V2 output from the force detection element 3b (that is, V2 × sin (φ)).
In addition, although the force detection apparatus 1a of this embodiment has a pair of force detection elements 3a and 3b, this invention is not limited to this. The force detection device 1a may include a plurality of pairs of force detection elements 3a and 3b, and such a case is also within the scope of the present invention.

Second Embodiment
Next, a second embodiment of the present invention will be described based on FIG. Hereinafter, the second embodiment will be described with a focus on the differences from the first embodiment described above, and the description of the same matters will be omitted. FIG. 4A is a perspective view schematically showing a second embodiment of the force detection device according to the present invention. FIG. 4B is a cross-sectional view schematically showing a second embodiment of the force detection device according to the present invention.

  In the force detection device 1a of the second embodiment, the angle φ of the first inclined portion 21 with respect to the first base 2 and the angle φ of the second inclined portion 41 with respect to the second base are π / 2, and the force The force detection elements 3a and 3b are arranged so that the polarization axis Pβ1 of the detection element 3a and the polarization axis Pβ2 of the force detection element 3b are opposite in the vertical direction (the stacking direction of the first base 2 and the second base 4). Except for this, it has the same configuration as the force detection device 1a of the first embodiment described above.

  In the present embodiment, the angle φ of the first inclined portion 21 with respect to the first base 2 and the angle φ of the second inclined portion 41 with respect to the second base 4 are π / 2. That is, the force detection elements 3 a and 3 b are provided in a state perpendicular to the first base 2. In this case, the 1st inclination part 21 and the 2nd inclination part 41 become a cylindrical member. The force detection elements 3 a and 3 b are sandwiched (held) between the outer peripheral portion of the first inclined portion 21 and the inner peripheral portion of the second inclined portion 41.

As shown in FIG. 4B, the force detection elements 3a and 3b are arranged such that the polarization axis Pβ1 of the force detection element 3a and the vertical component of the polarization axis Pβ2 of the force detection element 3b are opposite in the vertical direction. Is arranged.
Since the force detection elements 3a and 3b are arranged so that the polarization axis Pβ1 of the force detection element 3a and the polarization axis Pβ2 of the force detection element 3b face in opposite directions in the vertical direction, the voltage component included in the voltage V1 The signs of Vt1 and voltage component Vt2 included in voltage V2 do not match. For example, if the sign of the voltage component Vt1 is positive, the sign of the voltage component Vt2 is negative. Similarly, if the sign of the voltage component Vt1 is negative, the sign of the voltage component Vt2 is positive. Therefore, when the difference between the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b is taken, the absolute value of the difference between the voltage component Vt1 and the voltage component Vt2 does not decrease.
The external force detection circuit 5 obtains the difference between the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b as follows, thereby compressing / tensile force Fz applied to the force detection device 1a. Can be detected.

As described above, the force detection device 1a according to the present embodiment includes the force detection element 3a arranged so that the polarization axis Pβ1 of the force detection element 3a and the polarization axis Pβ2 of the force detection element 3b face in opposite directions in the vertical direction. 3b, and the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b are taken to detect the compression / tensile force Fz applied to the force detection device 1a. Since the external force detection circuit 5 is provided, the output drift D caused by the leakage current of the switching element 35 of the conversion circuit 32 can be reduced. As a result, the detection accuracy and detection resolution for the compression / tensile force Fz of the force detection device 1a can be improved.
In the illustrated configuration, the polarization axis Pβ1 of the force detection element 3a is directed downward in FIG. 4, and the polarization axis Pβ2 of the force detection element 3b is directed upward in FIG. Not limited. For example, the polarization axis Pβ1 of the force detection element 3a may be directed upward in FIG. 4, and the polarization axis Pβ2 of the force detection element 3b may be directed downward in FIG.

<Third Embodiment>
Next, a third embodiment of the present invention will be described based on FIG. 5, FIG. 6, and FIG. Hereinafter, the third embodiment will be described with a focus on differences from the first and second embodiments described above, and descriptions of similar matters will be omitted.
FIG. 5A is a perspective view schematically showing a second embodiment of the force detection device according to the present invention. FIG. 5B is a plan view schematically showing a second embodiment of the force detection device according to the present invention. FIG.5 (c) is sectional drawing along the A1 line shown in FIG.5 (b). FIG.5 (d) is sectional drawing along the A2 line shown in FIG.5 (b). FIG. 6 is a circuit diagram schematically showing the force detection device shown in FIG. FIG. 7A is a cross-sectional view schematically showing the charge output element of the first force detection device shown in FIG. FIG. 7B is a cross-sectional view schematically showing the charge output element of the second force detection device shown in FIG.

  The force detection device 1b shown in FIG. 5 has a function of detecting six-axis forces (translation force components in the x, y, and z axis directions and rotational force components around the x, y, and z axes). The force detection device 1b is inclined or perpendicular to the first base 2 between the first base 2, the second base 4 facing the first base 2, and the first base 2 and the second base 4. Voltage detectors 30a, 30b, 3c, and 30d that output voltages Vα, Vβ, and Vγ according to external forces, and voltages output from the force detectors 30a, 30b, 30c, and 30d, respectively. An external force detection circuit 50 (not shown in FIG. 5, see FIG. 6) for detecting six-axis forces based on Vα, Vβ, and Vγ is provided.

  The first inclined portion 21 provided on the surface of the first base 2 on the side facing the second base 4 and the first inclined portion 21 provided on the surface of the second base 4 on the side facing the first base 2. The second inclined portion 42 has the same configuration as that of the first embodiment described above except for the following points. That is, in the first embodiment, the angle φ that the inclined surface of the first inclined portion 21 has with respect to the first base 2 (the angle φ that the inclined surface of the second inclined portion 41 has with respect to the second base 4). Is arbitrarily set in the range of 0 <φ <π / 2, in the present embodiment, the angle φ is arbitrarily set in the range of 0 ≦ φ ≦ π / 2.

  In other words, in this embodiment, as in the first embodiment described above, force detection elements 30a, 30b, 30c, and 30d, which will be described later, are arranged in an inclined state with respect to the first base 2 (0 <Φ <π / 2), in addition, when the force detection elements 30a, 30b, 30c, 30d are arranged in parallel with the first base 2 (when φ = 0), As in the second embodiment, the case where the force detection elements 30a, 30b, 30c, and 30d are arranged in a state perpendicular to the first base 2 (when φ = π / 2) is also included.

  When the force detection elements 30a, 30b, 30c, and 30d are arranged in a state parallel to the first base 2 (when φ = 0), the height of the force detection device 1b can be kept low. This is advantageous for downsizing the force detection device 1b. In addition, when the force detection elements 30a, 30b, 30c, and 30d are arranged in an inclined state with respect to the first base 2 (0 <φ <π / 2), the force detection elements 30a, 30b, 30c, and 30d are The height of the force detection device 1b can be reduced compared to the case where the first base portion 2 is arranged in a state perpendicular to the first base 2 (φ = π / 2).

  On the other hand, when the force detection elements 30a, 30b, 30c, 30d are arranged in an inclined or perpendicular state with respect to the first base 2 (when 0 <φ <π / 2 and φ = π / 2), As described later, in addition to the voltages Vα and Vβ output from the force detection elements 30a, 30b, 30c, and 30d, the shear force (Fx, Fy) can be calculated using the voltage Vγ, Since the compression / tensile force (Fx) can be calculated using the voltage Vβ in addition to the voltage Vγ, the 6-axis force can be detected more accurately.

  Further, when the force detection elements 30a, 30b, 30c, and 30d are arranged in an inclined or perpendicular state with respect to the first base 2 (when 0 <φ <π / 2 and φ = π / 2), As in the first embodiment, the compression / tensile force (Fx) can be calculated from the voltage Vβ output from each output element. Therefore, it is possible to detect a six-axis force using only the voltages Vα and Vβ output from each force detection element. In this way, by using only the voltages Vα and Vβ output from each force detection element, force detection elements 30a, 30b, 30c, and 30d due to deformation caused by temperature changes of the first base portion 2 and the second base portion 4 are used. 6-axis force can be detected while reducing the influence of pressure change on

That is, when the first base 2 and the second base 4 are deformed due to a temperature change or the like, the pressure applied to the force detection elements 30a, 30b, 30c, and 30d changes. This pressure change is included in the voltages Vα, Vβ, and Vγ (charges Qα, Qβ, and Qγ) as noise components. As will be described later, the voltage Vγ (charge Qγ) output from each of the force detection elements 30a, 30b, 30c, and 30d is smaller than the voltages Vα and Vβ (charges Qβ and Qγ). The influence of the noise component resulting from the change is increased.
Therefore, by using only the voltages Vα and Vβ output from each of the force detection elements, force detection elements 30a, 30b, 30c, and 30d due to deformation caused by temperature changes of the first base portion 2 and the second base portion 4 are used. 6-axis force can be detected while reducing the influence of pressure change on

  Moreover, between the 1st base 2 and the 2nd base 4, it connects with connection tools, such as a pressurizing screw, and will apply a pressurization to force detection element 30a, 30b, 30c, 30d. At this time, when the force detection elements 30a, 30b, 30c, and 30d are arranged in a state perpendicular to the first base 2 (when φ = π / 2), each force detection element is connected to the first base 2. Since it is completely perpendicular to the surface, an external force is often applied in a direction where the rigidity of a general connecting device is low (for example, a direction perpendicular to the screw direction of the pressurizing screw). Therefore, from the viewpoint of the rigidity of the connecting device, when the force detection elements 30a, 30b, 30c, and 30d are arranged in a state of being parallel or inclined with respect to the first base 2 (φ = 0 and 0 <φ <π / 2) is more advantageous.

<Force detection element (element)>
The force detection elements 30a, 30b, 30c, and 30d have a function of outputting voltages Vα, Vβ, and Vγ according to external forces along three axes (α axis, β axis, and γ axis) that are orthogonal to each other. Further, the force detection elements 30a and 30c constitute a first element pair, and the force detection elements 30b and 30d constitute a second element pair. The force detection elements 30a and 30c belonging to the first element pair have the same configuration. The force detection elements 30b and 30d belonging to the second element pair have the same configuration.

  As shown in FIG. 6, the force detection elements 30a and 30c belonging to the first element pair have a charge Qα according to an external force applied along three axes (α axis, β axis, and γ axis) orthogonal to each other. , Qβ, Qγ are output from the first charge output element 301a, the conversion circuit 32a that converts the charge Qα output from the first charge output element 301a into the voltage Vα, and the first charge output element 301a. A conversion circuit 32b that converts the charge Qγ into a voltage Vγ, and a conversion circuit 32c that converts the charge Qβ output from the first charge output element 301a into a voltage Vβ. The force detection elements 30b and 30d belonging to the second element pair have a second charge output element 301b having a structure different from that of the first charge output element 301a, except that the force detection element 30a belongs to the first element pair. , 30c.

<Charge output element>
The first charge output element 301a shown in FIG. 7A has charges Qα, Qβ, and Qγ corresponding to external forces along three axes (α axis, β axis, and γ axis) orthogonal to each other in FIG. Has a function of outputting. As shown in FIG. 7A, the first charge output element 301a includes four ground electrode layers 310 grounded to the ground (reference potential point) and an external force (shearing force) parallel to the β axis. A first β-axis sensor 320 that outputs a charge Qβ, a first γ-axis sensor 330 that outputs a charge Qγ in response to an external force (compression / tensile force) parallel to the γ-axis, and a parallel to the α-axis The first α-axis sensor 340 outputs a charge Qα in accordance with an external force (shearing force), and the ground electrode layer 310 and the sensors 320, 330, and 340 are alternately stacked. In FIG. 7, the stacking direction of the ground electrode layer 310 and each of the sensors 320, 330, and 340 is the γ-axis direction, and the directions orthogonal to and orthogonal to the γ-axis direction are the α-axis direction and β-axis direction, respectively.

In the illustrated configuration, the first β-axis sensor 320, the first γ-axis sensor 330, and the first α-axis sensor 340 are stacked in this order from the lower side in FIG. Is not limited to this. The stacking order of the sensors 320, 330, and 340 is arbitrary.
The first β-axis sensor 320 has a function of outputting a charge Qβ in accordance with an external force (shearing force) parallel to the β-axis. The first β-axis sensor 320 has the same structure and function as the β-axis sensor 320 of the first embodiment described above.

  The first γ-axis sensor 330 has a function of outputting a charge Qγ according to an external force (compression / tensile force) parallel to the γ-axis. The first γ-axis sensor 330 is configured to output a positive charge according to an external force along the positive direction of the γ-axis and to output a negative charge according to an external force applied along the negative direction of the γ-axis. Has been. That is, the first γ-axis sensor 330 outputs the polarization axis (detection direction) Pγ of charge output according to the external force applied along the γ-axis direction in FIG. 7 (that is, the γ-axis in FIG. 7). The polarization axis Pγ) in the positive direction.

  The first γ-axis sensor 330 is provided opposite to the third piezoelectric layer 331 having the third crystal axis CA3 and the third piezoelectric layer 331, and has the fourth crystal axis CA4. 4, and an output electrode layer 332 that outputs a charge Qγ and is provided between the third piezoelectric layer 331 and the fourth piezoelectric layer 333. Further, the stacking order of the respective layers constituting the first γ-axis sensor 330 is the order of the third piezoelectric layer 331, the output electrode layer 332, and the fourth piezoelectric layer 333 from the lower side in FIG. is there.

  The third piezoelectric layer 331 is composed of a piezoelectric body having a third crystal axis CA3 oriented in the positive direction of the γ axis. When an external force along the positive direction of the γ-axis is applied to the surface of the third piezoelectric layer 331, electric charges are induced in the third piezoelectric layer 331 due to the piezoelectric effect. As a result, positive charges gather near the surface of the third piezoelectric layer 331 on the output electrode layer 332 side, and negative charges gather near the surface of the third piezoelectric layer 331 on the ground electrode layer 310 side. Similarly, when an external force applied along the negative direction of the γ-axis is applied to the surface of the third piezoelectric layer 331, the surface of the third piezoelectric layer 331 near the output electrode layer 332 side Negative charges gather, and positive charges gather near the surface of the third piezoelectric layer 331 on the ground electrode layer 310 side.

  The fourth piezoelectric layer 333 is composed of a piezoelectric body having a fourth crystal axis CA4 oriented in the negative direction of the γ axis. When an external force along the positive direction of the γ-axis is applied to the surface of the fourth piezoelectric layer 333, charges are induced in the fourth piezoelectric layer 333 due to the piezoelectric effect. As a result, positive charges gather near the surface of the fourth piezoelectric layer 333 on the output electrode layer 332 side, and negative charges gather near the surface of the fourth piezoelectric layer 333 on the ground electrode layer 310 side. Similarly, when an external force applied along the negative direction of the γ-axis is applied to the surface of the fourth piezoelectric layer 333, the surface of the fourth piezoelectric layer 333 near the output electrode layer 332 side surface Negative charges are collected, and positive charges are collected in the vicinity of the surface of the fourth piezoelectric layer 333 on the ground electrode layer 310 side.

  As the constituent material of the third piezoelectric layer 331 and the fourth piezoelectric layer 333, the same constituent material as that of the first piezoelectric layer 321 and the second piezoelectric layer 323 can be used. Further, like the third piezoelectric layer 331 and the fourth piezoelectric layer 333, a piezoelectric layer that generates an electric charge with respect to an external force (compression / tensile force) perpendicular to the plane direction of the layer is formed by an X-cut crystal. Can be configured.

  The output electrode layer 332 has a function of outputting positive charges or negative charges generated in the third piezoelectric layer 331 and the fourth piezoelectric layer 333 as charges Qγ. As described above, when an external force along the positive direction of the γ-axis is applied to the surface of the third piezoelectric layer 331 or the surface of the fourth piezoelectric layer 333, a positive charge is present in the vicinity of the output electrode layer 332. Gather. As a result, positive charge Qγ is output from the output electrode layer 332. On the other hand, when an external force applied along the negative direction of the γ-axis is applied to the surface of the third piezoelectric layer 331 or the surface of the fourth piezoelectric layer 333, a negative charge is present in the vicinity of the output electrode layer 332. Gather. As a result, a negative charge Qγ is output from the output electrode layer 332.

  The first α-axis sensor 340 has a function of outputting a charge Qα in accordance with an external force (shearing force) parallel to the α-axis. The first α-axis sensor 340 is configured to output a positive charge according to an external force along the positive direction of the α-axis and to output a negative charge according to an external force applied along the negative direction of the α-axis. Has been. In other words, the first α-axis sensor 340 outputs the charge polarization axis (detection direction) Pα (that is, the α-axis in FIG. 7) according to the external force applied along the α-axis direction in FIG. The polarization axis Pα) in the positive direction.

  The first α-axis sensor 340 is provided to face the fifth piezoelectric layer 341 having the fifth crystal axis CA5 and the fifth piezoelectric layer 341, and has the sixth crystal axis CA6. 6, and an output electrode layer 342 that outputs a charge Qα, which is provided between the fifth piezoelectric layer 341 and the sixth piezoelectric layer 343. Further, the stacking order of the layers constituting the first α-axis sensor 340 is the order of the fifth piezoelectric layer 341, the output electrode layer 342, and the sixth piezoelectric layer 343 from the lower side in FIG. is there.

  The fifth piezoelectric layer 341 is composed of a piezoelectric body having a fifth crystal axis CA5 oriented in the negative direction of the α axis. When an external force along the positive direction of the α axis is applied to the surface of the fifth piezoelectric layer 341, electric charges are induced in the fifth piezoelectric layer 341 by the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the fifth piezoelectric layer 341 on the output electrode layer 342 side, and negative charges are collected in the vicinity of the surface of the fifth piezoelectric layer 341 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 341, negative charges are generated near the surface of the fifth piezoelectric layer 341 on the output electrode layer 342 side. The positive charges are collected near the surface of the fifth piezoelectric layer 341 on the ground electrode layer 310 side.

  The sixth piezoelectric layer 343 is composed of a piezoelectric body having a sixth crystal axis CA6 oriented in the positive direction of the α axis. When an external force along the positive direction of the α axis is applied to the surface of the sixth piezoelectric layer 343, electric charges are induced in the sixth piezoelectric layer 343 due to the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the output electrode layer 342 side, and negative charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the sixth piezoelectric layer 343, negative charges are generated near the surface of the sixth piezoelectric layer 343 on the output electrode layer 342 side. As a result, positive charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the ground electrode layer 310 side.

  As the constituent material of the fifth piezoelectric layer 341 and the sixth piezoelectric layer 343, the same constituent material as that of the first piezoelectric layer 321 and the second piezoelectric layer 323 can be used. Further, like the fifth piezoelectric layer 341 and the sixth piezoelectric layer 343, the piezoelectric layer that generates an electric charge with respect to an external force (shearing force) along the surface direction of the layer is the first piezoelectric layer. Similarly to the 321 and the second piezoelectric layer 323, it can be composed of Y-cut quartz.

  The output electrode layer 342 has a function of outputting positive charges or negative charges generated in the fifth piezoelectric layer 341 and the sixth piezoelectric layer 343 as the charge Qα. As described above, when an external force along the positive direction of the α axis is applied to the surface of the fifth piezoelectric layer 341 or the surface of the sixth piezoelectric layer 343, a positive charge is present in the vicinity of the output electrode layer 342. Gather. As a result, a positive charge Qα is output from the output electrode layer 342. On the other hand, when an external force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 341 or the surface of the sixth piezoelectric layer 343, negative charges are collected in the vicinity of the output electrode layer 342. As a result, a negative charge Qα is output from the output electrode layer 342.

  The first β-axis sensor 320, the first γ-axis sensor 330, and the first α-axis sensor 340 include the direction of the polarization axis Pβ of the first β-axis sensor 320 and the first γ-axis. The direction of the polarization axis Pγ of the first sensor 330 and the direction of the polarization axis Pα of the first α-axis sensor 340 are stacked so as to be orthogonal to each other. As a result, the first charge output element 301a can have three polarization axes Pα, Pβ, and Pγ, and can have three polarization forces according to the external forces along the three axes (α axis, β axis, and γ axis). Charges Qα, Qβ, and Qγ can be output.

  Next, the second charge output element 301b included in the force detection elements 30b and 30d belonging to the second element pair will be described in detail with reference to FIG. The second charge output element 301b shown in FIG. 7B has charges Qα, Qβ, Qγ according to the external forces along the three axes (α axis, β axis, γ axis) orthogonal to each other in FIG. Has a function of outputting. As shown in FIG. 7B, the second charge output element 301b includes four ground electrode layers 310 grounded to the ground (reference potential point) and an external force (shearing force) parallel to the β axis. A second β-axis sensor 350 that outputs a charge Qβ, a second γ-axis sensor 360 that outputs a charge Qγ in response to an external force (compression / tensile force) parallel to the γ-axis, and a parallel to the α-axis A second α-axis sensor 370 that outputs a charge Qα according to an external force (shearing force) is provided, and the ground electrode layer 310 and the sensors 350, 360, and 370 are alternately stacked.

Accordingly, the second charge output element 301b includes a second β-axis sensor 350 having a structure different from that of the first β-axis sensor 320 and a second γ-axis having a structure different from that of the first γ-axis sensor 330. The first charge output element 301a has the same structure as the first charge output element 301a except that the first α-axis sensor 340 has a structure different from that of the first α-axis sensor 340. In FIG. 7, the stacking direction of the ground electrode layer 310 and the sensors 350, 360, and 370 is the γ-axis direction, and the directions orthogonal to and orthogonal to the γ-axis direction are the α-axis direction and β-axis direction, respectively.
In the illustrated configuration, the second β-axis sensor 350, the second γ-axis sensor 360, and the second α-axis sensor 370 are stacked in this order from the lower side in FIG. Is not limited to this. The stacking order of the sensors 350, 360, and 370 is arbitrary.

  The second β-axis sensor 350 has a function of outputting a charge Qβ in accordance with an external force (shearing force) parallel to the β-axis. The second β-axis sensor 350 is configured to output a negative charge according to an external force along the positive direction of the β axis and to output a positive charge according to an external force applied along the negative direction of the β axis. Has been. That is, the second β-axis sensor 350 is configured to output the polarization axis (detection direction) Pβ (that is, the β-axis in FIG. 7) of the electric charge output according to the external force applied along the β-axis direction in FIG. The polarization axis Pβ) in the negative direction. Accordingly, the direction of the polarization axis Pβ of the second β-axis sensor 350 is opposite to the direction of the polarization axis Pβ of the first β-axis sensor 320.

  The second β-axis sensor 350 is provided so as to face the second piezoelectric layer 323 having the second crystal axis CA2 and the second piezoelectric layer 323, and has the first crystal axis CA1. The first piezoelectric layer 321 is provided between the second piezoelectric layer 323 and the first piezoelectric layer 321 and has an output electrode layer 322 that outputs a charge Qβ. In addition, the stacking order of the layers constituting the second β-axis sensor 350 is the order of the second piezoelectric layer 323, the output electrode layer 322, and the first piezoelectric layer 321 from the lower side in FIG. is there. Accordingly, the second β-axis sensor 350 has the same structure as the first β-axis sensor 320 except for the stacking order of the second piezoelectric layer 323, the output electrode layer 322, and the first piezoelectric layer 321. Have

  When an external force along the positive direction of the β axis is applied to the surface of the second piezoelectric layer 323, electric charges are induced in the second piezoelectric layer 323 due to the piezoelectric effect. As a result, negative charges are collected near the surface of the second piezoelectric layer 323 on the output electrode layer 322 side, and positive charges are collected near the surface of the second piezoelectric layer 323 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the second piezoelectric layer 323, positive charges are generated near the surface of the second piezoelectric layer 323 on the output electrode layer 322 side. As a result, negative charges are collected in the vicinity of the surface of the second piezoelectric layer 323 on the ground electrode layer 310 side.

  When an external force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 321, electric charges are induced in the first piezoelectric layer 321 by the piezoelectric effect. As a result, negative charges are collected near the surface of the first piezoelectric layer 321 on the output electrode layer 322 side, and positive charges are collected near the surface of the first piezoelectric layer 321 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 321, a positive charge is generated near the surface of the first piezoelectric layer 321 on the output electrode layer 322 side. As a result, negative charges are collected in the vicinity of the surface of the first piezoelectric layer 321 on the ground electrode layer 310 side.

  Thus, when an external force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 321 or the surface of the second piezoelectric layer 323, negative charges are generated in the vicinity of the output electrode layer 322. get together. As a result, a negative charge Qγ is output from the output electrode layer 322. On the other hand, when an external force along the negative direction of the γ axis is applied to the surface of the first piezoelectric layer 321 or the surface of the second piezoelectric layer 323, positive charges are collected in the vicinity of the output electrode layer 322. As a result, positive charge Qγ is output from the output electrode layer 322.

  The second γ-axis sensor 360 has a function of outputting a charge Qγ according to an external force (compression / tensile force) parallel to the γ-axis. The second γ-axis sensor 360 outputs a negative charge according to an external force along the positive direction of the γ-axis, and outputs a positive charge according to an external force applied along the negative direction of the γ-axis. Has been. That is, the second γ-axis sensor 360 outputs the polarization axis (detection direction) Pγ of the electric charge output according to the external force applied along the γ-axis direction in FIG. 7 (that is, the γ-axis in FIG. 7). The polarization axis Pγ) in the negative direction. Therefore, the direction of the polarization axis Pγ of the second γ-axis sensor 360 is opposite to the direction of the polarization axis Pγ of the first γ-axis sensor 330.

  The second γ-axis sensor 360 is provided so as to face the fourth piezoelectric layer 333 having the fourth crystal axis CA4 and the fourth piezoelectric layer 333, and has the third crystal axis CA3. 3, and an output electrode layer 332 that outputs a charge Qγ and is provided between the fourth piezoelectric layer 333 and the third piezoelectric layer 331. Further, the stacking order of the respective layers constituting the second γ-axis sensor 360 is the order of the fourth piezoelectric layer 333, the output electrode layer 332, and the third piezoelectric layer 331 from the lower side in FIG. is there. Therefore, the second γ-axis sensor 360 has the same structure as the first γ-axis sensor 330 except for the stacking order of the fourth piezoelectric layer 333, the output electrode layer 332, and the third piezoelectric layer 331. Have

  When an external force along the positive direction of the γ-axis is applied to the surface of the fourth piezoelectric layer 333, charges are induced in the fourth piezoelectric layer 333 due to the piezoelectric effect. As a result, negative charges are collected near the surface of the fourth piezoelectric layer 333 on the output electrode layer 332 side, and positive charges are collected near the surface of the fourth piezoelectric layer 333 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the γ axis is applied to the surface of the fourth piezoelectric layer 333, a positive charge is generated near the surface of the fourth piezoelectric layer 333 on the output electrode layer 332 side. As a result, negative charges are collected near the surface of the fourth piezoelectric layer 333 on the ground electrode layer 310 side.

  When an external force along the positive direction of the γ-axis is applied to the surface of the third piezoelectric layer 331, electric charges are induced in the third piezoelectric layer 331 due to the piezoelectric effect. As a result, negative charges are collected in the vicinity of the surface of the third piezoelectric layer 331 on the output electrode layer 332 side, and positive charges are collected in the vicinity of the surface of the third piezoelectric layer 331 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the γ axis is applied to the surface of the third piezoelectric layer 331, a positive charge is generated near the surface of the third piezoelectric layer 331 on the output electrode layer 332 side. The negative charges are collected near the surface of the third piezoelectric layer 331 on the ground electrode layer 310 side.

  Thus, when an external force along the positive direction of the γ-axis is applied to the surface of the third piezoelectric layer 331 or the surface of the fourth piezoelectric layer 333, negative charges are generated in the vicinity of the output electrode layer 332. get together. As a result, a negative charge Qγ is output from the output electrode layer 332. On the other hand, when an external force along the negative direction of the γ axis is applied to the surface of the third piezoelectric layer 331 or the surface of the fourth piezoelectric layer 333, positive charges are collected in the vicinity of the output electrode layer 332. As a result, positive charge Qγ is output from the output electrode layer 332.

  The second α-axis sensor 370 has a function of outputting a charge Qα in accordance with an external force (shearing force) parallel to the α-axis. The second α-axis sensor 370 is configured to output a negative charge according to an external force along the positive direction of the α-axis and to output a positive charge according to an external force applied along the negative direction of the α-axis. Has been. That is, the second α-axis sensor 370 outputs the polarization axis (detection direction) Pα (that is, the α-axis in FIG. 7) of the charge that is output according to the external force applied along the α-axis direction in FIG. The polarization axis Pα) in the negative direction. Therefore, the direction of the polarization axis Pα of the second α-axis sensor 370 is opposite to the direction of the polarization axis Pα of the first α-axis sensor 340.

  The second α-axis sensor 370 is provided to face the sixth piezoelectric layer 343 having the sixth crystal axis CA6 and the sixth piezoelectric layer 343, and has the fifth crystal axis CA5. 5, and an output electrode layer 342 that outputs a charge Qα and is provided between the sixth piezoelectric layer 343 and the fifth piezoelectric layer 341. Further, the stacking order of the layers constituting the second α-axis sensor 370 is as follows: from the lower side in FIG. 7 to the sixth piezoelectric layer 343, the output electrode layer 342, and the fifth piezoelectric layer 341. is there. Therefore, the second α-axis sensor 370 has the same structure as the first α-axis sensor 340 except for the stacking order of the sixth piezoelectric layer 343, the output electrode layer 342, and the fifth piezoelectric layer 341. Have

  When an external force along the positive direction of the α axis is applied to the surface of the sixth piezoelectric layer 343, electric charges are induced in the sixth piezoelectric layer 343 due to the piezoelectric effect. As a result, negative charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the output electrode layer 342 side, and positive charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the sixth piezoelectric layer 343, a positive charge is generated near the surface of the sixth piezoelectric layer 343 on the output electrode layer 342 side. As a result, negative charges are collected in the vicinity of the surface of the sixth piezoelectric layer 343 on the ground electrode layer 310 side.

  When an external force along the positive direction of the α axis is applied to the surface of the fifth piezoelectric layer 341, electric charges are induced in the fifth piezoelectric layer 341 by the piezoelectric effect. As a result, negative charges gather near the surface of the fifth piezoelectric layer 341 on the output electrode layer 342 side, and positive charges gather near the surface of the fifth piezoelectric layer 341 on the ground electrode layer 310 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 341, a positive charge is generated near the surface of the fifth piezoelectric layer 341 on the output electrode layer 342 side. As a result, negative charges are collected in the vicinity of the surface of the fifth piezoelectric layer 341 on the ground electrode layer 310 side.

  As described above, when an external force along the positive direction of the α axis is applied to the surface of the fifth piezoelectric layer 341 or the surface of the sixth piezoelectric layer 343, negative charges are generated in the vicinity of the output electrode layer 342. get together. As a result, a negative charge Qα is output from the output electrode layer 342. On the other hand, when an external force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 341 or the surface of the sixth piezoelectric layer 343, positive charges are collected in the vicinity of the output electrode layer 342. As a result, positive charge Qα is output from the output electrode layer 322.

  The second β-axis sensor 350, the second γ-axis sensor 360, and the second α-axis sensor 370 include the direction of the polarization axis Pβ of the second β-axis sensor 350 and the second γ-axis. It is laminated so that the direction of the polarization axis Pγ of the sensor 360 for use and the direction of the polarization axis Pα of the second sensor 370 for the α-axis are orthogonal to each other. The direction of the polarization axis Pβ of the second β-axis sensor 350 is opposite to the direction of the polarization axis Pβ of the first β-axis sensor 320. The direction of the polarization axis Pγ of the second γ-axis sensor 360 is opposite to the direction of the polarization axis Pγ of the first γ-axis sensor 330. Similarly, the direction of the polarization axis Pα of the second α-axis sensor 370 is opposite to the direction of the polarization axis Pα of the first α-axis sensor 340.

  Further, the charge per unit force of the first β-axis sensor 320, the second β-axis sensor 350, the first α-axis sensor 340, and the second α-axis sensor 370 constituted by the Y-cut crystal. The generation amount is, for example, 8 pC / N. On the other hand, the charge generation amount per unit force of the first γ-axis sensor 330 and the second γ-axis sensor 360 formed of X-cut quartz is, for example, 4 pC / N. As described above, the sensitivity of the first charge output element 301a and the second charge output element 301b to the external force (compression / tensile force) parallel to the γ-axis is usually the first charge output element 301a and the second charge output. The sensitivity of the output element 301b to an external force (shearing force) parallel to the α-axis or β-axis is below. Therefore, normally, the charge Qγ output from the first charge output element 301a and the second charge output element 301b is equal to the charge Qα and the charge output from the first charge output element 301a and the second charge output element 301b. Qβ or less.

<Conversion circuit>
The conversion circuits 32a and 32c have the same configuration as the conversion circuit 32 of the first embodiment. The conversion circuit 32b has the same configuration as the conversion circuit 32 of the first embodiment except for the capacitance of the capacitor 34. The conversion circuit 32a has a function of converting the charge Qα output from the first charge output element 301a or the second charge output element 301b into a voltage Vα. The conversion circuit 32b has a function of converting the charge Qγ output from the first charge output element 301a or the second charge output element 301b into a voltage Vγ. The conversion circuit 32c has a function of converting the charge Qβ output from the first charge output element 301a or the second charge output element 301b into a voltage Vβ.

  The same drive circuit may be connected to the switching element 35 of each conversion circuit 32a, 32b, 32c, or a different drive circuit may be connected thereto. Each switching element 35 receives an on / off signal that is all synchronized from the drive circuit. Thereby, operation | movement of the switching element 35 of each conversion circuit 32a, 32b, 32c synchronizes. That is, the on / off timings of the switching elements 35 of the conversion circuits 32a, 32b, and 32c are the same.

Further, in a circuit having a voltage conversion function such as the conversion circuits 32a, 32b, and 32c, if the capacitance of the capacitor 34 is reduced, the voltage conversion sensitivity is improved, but the saturation charge amount is reduced. As described above, normally, the charge Qγ output from the first charge output element 301a and the second charge output element 301b is the charge output from the first charge output element 301a and the second charge output element 301b. Qα and charge Qβ or less. Therefore, from the viewpoint of sensitivity to the charge Qγ, the capacitance C2 of the capacitor 34 of the conversion circuit 32b is preferably less than or equal to the capacitance C1 of the capacitor 34 of the conversion circuits 32a and 32c. Thereby, the charge Qγ can be accurately converted into the voltage Vγ.
The switching elements 35 of the conversion circuits 32a, 32b, and 32c are semiconductor switching elements that are equivalent to each other, and the leakage currents of the switching elements 35 are substantially equal. Therefore, the output drift D of each switching element 35 is also substantially equal.

  Next, referring to FIGS. 5B, 5C and 5D, the positions of the force detection elements 30a and 30c forming the first element pair and the force detection elements 30b and 30d forming the second element pair. Details the relationship. In FIG. 5B, the second base 4 is omitted for explanation. 5B, the left-right direction is the x-axis direction, the direction orthogonal to the x-axis direction, that is, the vertical direction is the y-axis direction, and the direction orthogonal to the x-axis direction and the y-axis direction is the z-axis direction. Further, in FIG. 5B, a straight line passing through the centers of the force detection elements 30a and 30c is defined as an A1 line, and a straight line passing through the centers of the force detection elements 30b and 30d is defined as an A2 line. FIG.5 (c) is sectional drawing along the A1 line of FIG.5 (b). FIG. 5D is a cross-sectional view taken along the line A2 in FIG.

  The force detection element 30a has polarization axes Pα1, Pβ1, and Pγ1, and outputs voltages Vα1, Vβ1, and Vγ1 according to external forces along the α axis, β axis, and γ axis, respectively. The force detection element 30b has polarization axes Pα2, Pβ2, and Pγ2, and outputs voltages Vα2, Vβ2, and Vγ2 according to external forces along the α axis, β axis, and γ axis, respectively. The force detection element 30c has polarization axes Pα3, Pβ3, and Pγ3, and outputs voltages Vα3, Vβ3, and Vγ3 according to external forces along the α axis, β axis, and γ axis, respectively. Similarly, the force detection element 30d has polarization axes Pα4, Pβ4, and Pγ4, and outputs voltages Vα4, Vβ4, and Vγ4 according to external forces along the α-axis, β-axis, and γ-axis, respectively. The voltages Vα, Vβ, and Vγ output from the force detection elements 30a, 30b, 30c, and 30d are voltage components (true values) Vαt, Vβt, proportional to the amount of charge accumulated in the capacitor 34, respectively. Vγt and the output drift D caused by the leakage current of the switching element 35 are included.

  The force detection elements 30a, 30b, 30c, and 30d are fixedly disposed on the inclined surface of the first inclined portion 21, and are sandwiched (held) between the first inclined portion 21 and the second inclined portion 41. Has been. That is, the force detection elements 30a, 30b, 30c, and 30d are parallel to the first base 2 (φ = 0) and inclined (0 <φ <π /) between the first base 2 and the second base 4. 2) or in a vertical state (φ = π / 2).

  The polarization axis Pβ1 of the force detection element 30a has an angle θ1 in the horizontal direction (xy plane). The polarization axis Pβ2 of the force detection element 30b has a horizontal angle θ2. The polarization axis Pβ3 of the force detection element 30c has a horizontal angle θ3. The polarization axis Pβ4 of the force detection element 30d has a horizontal angle θ4. The angles θ1, θ2, θ3, and θ4 are angles from the x-axis of the reference coordinate system (x-axis, y-axis, and z-axis) in FIG. Furthermore, the polarization axes Pβ of the force detection elements 30a, 30b, 30c, and 30d each have an angle φ in the vertical direction (a plane including the z-axis direction). Note that the angle φ is an angle with respect to the xy plane of the reference coordinate system in FIG.

  As shown in FIGS. 5B and 5C, the force detection elements 30a and 30c forming the first element pair include a horizontal component (x, y component) of the polarization axis Pβ1 of the force detection element 30a and force detection. The horizontal component of the polarization axis Pβ3 of the element 30c is arranged to face in the opposite direction. Furthermore, the force detection elements 30a and 30c are arranged such that the polarization axis Pα1 of the force detection element 30a and the polarization axis Pα3 of the force detection element 30c face in opposite directions.

  Similarly, as shown in FIGS. 5B and 5D, the force detection elements 30b and 30d forming the second element pair include the horizontal component of the polarization axis Pβ2 of the force detection element 30b and the force detection element 30d. The horizontal component of the polarization axis Pβ4 is arranged to face in the opposite direction. Furthermore, the force detection elements 30a and 30c are arranged such that the polarization axis Pα2 of the force detection element 30b and the polarization axis Pα4 of the force detection element 30d face in opposite directions.

Further, as shown in FIGS. 5C and 5D, the vertical components (z components) of the polarization axes Pγ1 and Pγ3 of the force detection elements 30a and 30c forming the first element pair and the second element pair are The perpendicular components of the polarization axes Pγ2 and Pγ4 of the force detection elements 30b and 30d are oriented in opposite directions.
As shown in FIG. 5C, the force detection elements 30a and 30c include a horizontal component of the polarization axis Pβ1 of the force detection element 30a (that is, Pβ1 × cos (φ)) and a polarization axis Pβ2 of the force detection element 30c. The horizontal components (that is, Pβ3 × cos (φ)) are arranged in opposite directions. Therefore, the horizontal component of the voltage component Vβt1 included in the voltage Vβ1 (that is, Vβt1 × cos (φ)) and the horizontal component of the voltage component Vβt3 included in the voltage Vβ3 (that is, Vβt3 × cos (φ)) match. do not do. Therefore, when the difference between the horizontal component of the voltage Vβ1 output from the force detection element 30a and the horizontal component of the voltage Vβ3 output from the force detection element 30c is taken, the horizontal component of the voltage component Vβt1 and the horizontal component of the voltage component Vβt3 are obtained. The absolute value of the difference from the component does not decrease.

  Similarly, as shown in FIG. 5C, in the force detection elements 30a and 30c, the direction of the polarization axis Pα1 of the force detection element 30a and the direction of the polarization axis Pα2 of the force detection element 30c are opposite to each other. Thus, the signs of the voltage component Vαt1 included in the voltage Vα1 and the voltage component Vαt3 included in the voltage Vα3 do not match. Therefore, when the difference between the voltage Vα1 output from the force detection element 30a and the voltage Vα3 output from the force detection element 30c is taken, the absolute value of the difference between the voltage component Vαt1 and the voltage component Vαt3 does not decrease.

  Further, as shown in FIG. 5 (d), the force detection elements 30b and 30d include a horizontal component of the polarization axis Pβ2 of the force detection element 30b (that is, Pβ2 × cos (φ)) and a polarization axis of the force detection element 30d. The horizontal components of Pβ4 (that is, Pβ4 × cos (φ)) are arranged in opposite directions. Therefore, the horizontal component of the voltage component Vβt2 included in the voltage Vβ2 (that is, Vβt2 × cos (φ)) and the horizontal component of the voltage component Vβt4 included in the voltage Vβ4 (that is, Vβ4 × cos (φ)) are the same. do not do. Therefore, when the difference between the horizontal component of the voltage Vβ2 output from the force detection element 30b and the horizontal component of the voltage Vβ4 output from the force detection element 30d is taken, the absolute value of the difference between the voltage component Vβt2 and the voltage component Vβt4 Does not decrease.

  Similarly, as shown in FIG. 5D, in the force detection elements 30b and 30d, the direction of the polarization axis Pα2 of the force detection element 30b and the direction of the polarization axis Pα4 of the force detection element 30d are opposite to each other. Thus, the signs of the voltage component Vαt2 included in the voltage Vα2 and the voltage component Vαt4 included in the voltage Vα4 do not match. Therefore, when the difference between the voltage Vα2 output from the force detection element 30b and the voltage Vα4 output from the force detection element 30d is taken, the absolute value of the difference between the voltage component Vαt2 and the voltage component Vαt4 does not decrease.

  Further, as shown in FIGS. 5C and 5D, the force detection elements 30a, 30c, 30b, and 30d are perpendicular components of the polarization axes Pγ1 and Pγ3 of the force detection elements 30a and 30c (that is, Pγ1 × sin ( π / 2−φ) and Pγ3 × sin (π / 2−φ)) and vertical components of the polarization axes Pγ2 and Pγ4 of the force detection elements 30b and 30d (that is, Pγ2 × sin (π / 2−φ) and Pγ4 × sin (π / 2−φ)) are directed in opposite directions to each other, so that the vertical components of the voltage components Vγt1 and Vγt3 included in the voltages Vγ1 and Vγ3 (that is, Vγt1 × sin (π / 2) −φ) and Vγt3 × sin (π / 2−φ)) and vertical components of voltage components Vγt2 and Vγt4 included in the voltages Vγ2 and Vγ4 (that is, Vγt2 × sin (π / 2−φ) and Vγt4 × sin ( π / 2-φ)) The signs do not match. Therefore, when the difference between the vertical components of the voltages Vγ1 and Vγ3 output from the force detection elements 30a and 30c and the vertical components of the voltages Vγ2 and Vγ4 output from the force detection elements 30b and 30d is taken, The absolute value does not decrease.

On the other hand, since the output drift D included in the voltages Vα, Vβ, and Vγ output from the force detection elements 30a, 30b, 30c, and 30d does not depend on the directions of the polarization axes Pα, Pβ, and Pγ, the voltages Vα, Vβ , Vγ have the same sign of the output drift D. Therefore, when the difference of each output drift D is taken, the absolute value of the difference decreases.
Further, the force detection elements 30a and 30c constituting the first element pair are arranged so that the horizontal component of the polarization axis Pβ1 and the horizontal component of the polarization axis Pβ3 face each other, that is, satisfy the relationship θ1 = θ3. Is preferred. Similarly, the force detection elements 30b and 30d constituting the second element pair are arranged so that the horizontal component of the polarization axis Pβ2 and the horizontal component of the polarization axis Pβ4 face each other, that is, satisfy the relationship θ2 = θ4. It is preferable. Thereby, the external force detection circuit 50 described later can detect the 6-axis force while reducing the output drift D.

  The force detection elements 30a, 30b, 30c, and 30d are the horizontal components of the polarization axes Pβ1 and Pβ3 of the force detection elements 30a and 30c constituting the first element pair and the force detection elements constituting the second element pair. More preferably, the horizontal axes of the polarization axes Pβ2 and Pβ4 of 30b and 30d are arranged so as to be orthogonal to each other. Thereby, the external force detection circuit 50 described later can detect the six-axis force while further reducing the output drift D.

  Further, if the horizontal component of the polarization axis Pβ1 of the force detection element 30a and the horizontal component of the polarization axis Pβ3 of the force detection element 30c are arranged to face in opposite directions, the force detection element forming the first element pair Although arrangement | positioning of 30a, 30c is not specifically limited, As shown in FIG.4 (b), it is preferable that the force detection element 30a and the force detection element 30c are arrange | positioned on the same axis | shaft A1. Similarly, if the horizontal component of the polarization axis Pβ2 of the force detection element 30b and the horizontal component of the polarization axis Pβ4 of the force detection element 30d are arranged to face in opposite directions, the force detection forming the second element pair is detected. The arrangement of the elements 30b and 30d is not particularly limited, but it is preferable that the force detection element 30b and the force detection element 30d are arranged on the same axis A2, as shown in FIG. Thereby, the 6-axis force applied to the 1st base 2 or the 2nd base 4 is detectable without bias.

  Further, although the positional relationship between the first element pair and the second element pair is not particularly limited, as shown in FIG. 4B, the center of the force detection element 30a belonging to the first element pair and the force detection element The first element pair and the second element so that the straight line A1 connecting the center of 30c and the straight line A2 connecting the center of the force detection element 30b belonging to the second element pair and the center of the force detection element 30d are orthogonal to each other. It is preferable to arrange element pairs. Thereby, it is possible to detect the external force applied to the first base 2 or the second base 4 (external forces along the x-axis, y-axis, and z-axis in the figure) without any deviation.

  The force detection elements 30a, 30b, 30c, and 30d are preferably arranged at equiangular intervals along the circumferential direction of the first base 2 or the second base 4, and the first base 2 or the second base More preferably, they are arranged at equal intervals in a concentric manner with the center point of 4 as the center. Thereby, it is possible to detect the external force applied to the first base 2 or the second base 4 (external forces along the x-axis, y-axis, and z-axis in the figure) without any deviation.

  In the configuration of FIG. 4B, the polarization axes Pβ1 and Pβ3 of the force detection elements 30a and 30c face the outside (centrifugal direction) of the first base 2, and the polarization axes Pβ2 and Pβ4 of the force detection elements 30b and 30d are Although it faces the inner side (centric direction) of the first base 2, the present invention is not limited to this. That is, the direction of the polarization axis Pβ1 of the force detection element 30a and the direction of the polarization axis Pβ3 of the force detection element 30c are opposite to each other, the direction of the polarization axis Pβ2 of the force detection element 30b, and the force detection element 30d If the polarization axes Pβ1 and Pβ3 of the force detection elements 30a and 30c are directed to the inner side (centric direction) of the first base portion 2, The polarization axes Pβ2 and Pβ4 of 30b and 30d may face the outside of the first base 2 (centrifugal direction).

<External force detection circuit>
The external force detection circuit 50 calculates the translational force component (shearing force) Fx, y-axis in the x-axis direction by taking the difference between the voltages Vα, Vβ, Vγ output from the force detection elements 30a, 30b, 30c, 30d. Direction translational force component (shearing force) Fy, z-axis direction translational force component (compression / tensile force) Fz, rotational force component Mx around x-axis, rotational force component My around y-axis, rotational force around z-axis It has a function of calculating the six-axis force of the component Mz. Each force component can be obtained by the following equation. For simplification of the equation, the force detection elements 30a, 30b, 30c, and 30d have a radius L with the center point of the first base 2 or the second base 4 as the center as shown in FIG. Although it shall be arrange | positioned concentrically, this invention is not limited to this.

Here, L is a constant.
In this way, the capacitor 34 is obtained by taking the difference between the voltages Vα (that is, Vαt + D), Vβ (that is, Vβt + D), and Vγ (that is, Vγt + D) output from the force detection elements 30a, 30b, 30c, and 30d. The absolute value of the difference between the voltage components (true values) Vαt, Vβt, and Vγt proportional to the amount of charge accumulated in the output can be decreased, and the absolute value of the output drift D can be decreased. As a result, the output drift D can be reduced, and the detection accuracy and detection resolution of the force detection device 1b can be improved. Moreover, since the method for reducing the output drift D described above is effective even when the measurement time is long, the measurement time of the force detection device 1b can be lengthened.

  Further, as can be seen from the above expression, except for the case where the angle φ = 0, even if all the Vγs output from the force detection elements 30a, 30b, 30c, and 30d are Vγ = 0, the six-axis force (Fx, Fy, Fz, Mx, My, Mz) can be calculated. That is, except for the case where the angle φ = 0, the six-axis force can be calculated using only the voltages Vα and Vβ output from the force detection elements 30a, 30b, 30c, and 30d.

  As described above, the influence of the noise component caused by the temperature change of the first base 2 and the second base 4 on the voltages Vα and Vβ output from the force detection elements 30a, 30b, 30c, and 30d is the voltage Vγ. It is smaller than the influence of noise components due to temperature changes. Therefore, when the force detection elements 30a, 30b, 30c, and 30d are arranged in a state inclined or perpendicular to the first base 2 (when 0 <φ <π / 2 and φ = π / 2). By detecting 6-axis force using only the voltages Vα and Vβ output from each of the force detection elements, each force is detected by deformation caused by temperature changes of the first base 2 and the second base 4. It is possible to detect the six-axis force while reducing the influence of the pressure change on the element.

  When the force detection elements 30a, 30b, 30c, 30d are arranged in an inclined or perpendicular state to the first base 2 (when 0 <φ <π / 2 and φ = π / 2), an external force Whether the detection circuit 50 calculates the 6-axis force using only the voltages Vα and Vβ output from each output element or the 6-axis force using the voltages Vα, Vβ, and Vγ is arbitrarily determined by the user. Can be set.

  In an environment in which the fluctuation of the voltage Vγ due to the deformation of the first base 2 and the second base 4 due to the temperature change of the first base 2 and the second base 4 is so large that it cannot be ignored with respect to the true value Vγt of the voltage Vγ. When the detection device 1b is used, the external force detection circuit 50 is set to calculate the six-axis force using only the voltages Vα and Vβ, thereby reducing the influence of deformation of the first base 2 and the second base 4. Thus, the six-axis force can be detected more accurately.

On the other hand, in an environment where the fluctuation of the voltage Vγ due to the deformation of the first base 2 and the second base 4 due to the temperature change of the first base 2 and the second base 4 is so small that it can be ignored with respect to the true value Vγt of the voltage Vγ. When the force detection device 1b is used, the external force detection circuit 50 is set so as to calculate the six-axis force using the voltages Vα, Vβ, and Vγ, so that more inputs (voltages Vα, Vβ than in the above case). , Vγ) is used to detect the six-axis force, so that the six-axis force can be detected more accurately.
When the angles θ1, θ2, θ3, and θ4 satisfy θ1 = θ3 and θ2 = θ4, the above calculation formula is simplified and becomes as follows.

In this case, the output drift D can be removed. As a result, the detection accuracy and detection resolution of the force detection device 1b can be further improved. Further, the measurement time of the force detection device 1b can be further increased.
Further, when the angles θ1, θ2, θ3, and θ4 satisfy θ1 = θ3 = π / 2 and θ2 = θ4 = 0, the calculation formula is further simplified as follows.

  Further, when the angle φ = 0 is satisfied, the calculation formula is further simplified as follows.

  Further, when the angle φ = π / 2 is satisfied, the above calculation formula is as follows.

  Thus, the external force detection circuit 50 takes the difference between the voltages Vα, Vβ, and Vγ output from the force detection elements 30a, 30b, 30c, and 30d, thereby switching the switching elements 35 of the conversion circuits 32a, 32b, and 32c. 6-axis force can be detected while reducing the output drift D caused by the leakage current. As a result, the detection error caused by the leak current (output drift D) is relatively small, and the detection accuracy and detection resolution of the force detection device 1b can be improved. Moreover, since the method for reducing the output drift D described above is effective even when the measurement time is long, the measurement time of the force detection device 1b can be lengthened. Furthermore, since the force detection device 1b according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1b can be downsized.

  Note that the force detection device 1b according to the present embodiment has two element pairs, ie, force detection elements 30a and 30c forming a first element pair and force detection elements 30c and 30d forming a second element pair. However, the present invention is not limited to this. When the force detection device 1b has two element pairs, ie, the first element pair and the second element pair as shown in FIG. 5B, as described above, a very simple operation is performed. Since the 6-axis force can be obtained, the external force detection circuit 50 can be simplified. Further, when the force detection device 1b has three or more pairs of elements, the six-axis force can be detected with higher accuracy.

<Fourth embodiment>
Next, based on FIG. 8, the single-arm robot which is 4th Embodiment of this invention is demonstrated. Hereinafter, the fourth embodiment will be described with a focus on differences from the first, second, and third embodiments described above, and description of similar matters will be omitted.
FIG. 8 is a diagram showing an example of a single-arm robot using the force detection device 1 (1a or 1b) according to the present invention. The single-arm robot 500 of FIG. 8 is provided between a base 510, an arm coupling body 520, an end effector 530 provided on the distal end side of the arm coupling body 520, and between the arm coupling body 520 and the end effector 530. And a force detection device 1 (1a or 1b) according to the present invention.

The base 510 has a function of accommodating an actuator (not shown) that generates power for rotating the arm coupling body 520, a control unit (not shown) that controls the actuator, and the like. The base 510 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage.
The arm connection body 520 includes a first arm 521, a second arm 522, a third arm 523, a fourth arm 524, and a fifth arm 525, and the adjacent arms can be rotated freely. It is configured by connecting. The arm coupling body 520 is driven by being rotated or bent in a compound manner around the coupling portion of each arm under the control of the control unit.
The end effector 530 has a function of gripping an object. The end effector 530 has a first finger 531 and a second finger 532. After the end effector 530 reaches a predetermined operating position by driving the arm connector 520, the object can be gripped by adjusting the distance between the first finger 531 and the second finger 532.

The force detection device 1 has a function of detecting an external force applied to the end effector 530. By feeding back the external force detected by the force detection device 1 to the control unit of the base 510, the single-arm robot 500 can perform more precise work. Further, the single-arm robot 500 can detect contact of the end effector 530 with an obstacle by the six-axis force detected by the force detection device 1. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like, which are difficult with conventional position control, can be easily performed, and the single-arm robot 500 can perform work more safely. Furthermore, since the force detection device 1 according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1 can be downsized. Therefore, the single arm robot 500 can be reduced in size.
In the illustrated configuration, the arm coupling body 520 is configured by a total of five arms, but the present invention is not limited to this. When the arm connection body 520 is constituted by one arm, when constituted by 2 to 4 arms, when constituted by 6 or more arms, it is within the scope of the present invention.

<Fifth Embodiment>
Next, based on FIG. 9, the multi-arm robot which is 4th Embodiment of this invention is demonstrated. Hereinafter, the fifth embodiment will be described with a focus on differences from the first, second, third, and fourth embodiments described above, and description of similar matters will be omitted.
FIG. 9 is a diagram showing an example of a multi-arm robot using the force detection device 1 (1a or 1b) according to the present invention. 9 includes a base 610, a first arm coupling body 620, a second arm coupling body 630, and a first end provided on the distal end side of the first arm coupling body 620. The effector 640a, the second end effector 640b provided on the distal end side of the second arm connector 630, the first arm connector 620 and the first end effector 640a, and the second arm connector 630 The force detection device 1 (1a or 1b) according to the present invention is provided between the second end effector 640b.

The base 610 includes an actuator (not shown) that generates power for rotating the first arm connecting body 620 and the second arm connecting body 630, a control unit (not shown) that controls the actuator, and the like. Has the function of storing. The base 610 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage.
The 1st arm coupling body 620 is comprised by connecting the 1st arm 621 and the 2nd arm 622 so that rotation is possible. The second arm coupling body 630 is configured by pivotably coupling the first arm 631 and the second arm 632. The first arm coupling body 620 and the second arm coupling body 630 are driven by complex rotation or bending around the coupling portion of each arm under the control of the control unit.

  The first end effector 640a and the second end effector 640b have a function of gripping an object. The first end effector 640a has a first finger 641a and a second finger 642a. The second end effector 640b has a first finger 641b and a second finger 642b. After the first end effector 640a reaches a predetermined operating position by driving the first arm coupling body 620, the object is grasped by adjusting the separation distance between the first finger 641a and the second finger 642a. can do. Similarly, after the second end effector 640b reaches the predetermined operating position by driving the second arm coupling body 630, the distance between the first finger 641b and the second finger 642b is adjusted, thereby adjusting the target. An object can be gripped.

The force detection device 1 has a function of detecting an external force applied to the first end effector 640a or the second end effector 640b. By feeding back the external force detected by the force detection device 1 to the control unit of the base 610, the multi-arm robot 600 can perform the operation more precisely. The multi-arm robot 600 can detect contact of the first end effector 640a or the second end effector 640b with an obstacle by the six-axis force detected by the force detection device 1. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that have been difficult with conventional position control can be easily performed, and the multi-arm robot 600 can perform the operation more safely. Furthermore, since the force detection device 1 according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1 can be downsized. Therefore, the double-arm robot 600 can be reduced in size.
In the configuration shown in the figure, there are a total of two arm connectors, but the present invention is not limited to this. The case where the multi-arm robot 600 includes three or more arm coupling bodies is also within the scope of the present invention.

<Sixth Embodiment>
Next, based on FIGS. 10 and 11, an electronic component inspection apparatus and an electronic component transport apparatus according to a sixth embodiment of the present invention will be described. Hereinafter, the sixth embodiment will be described with a focus on differences from the first, second, third, fourth, and fifth embodiments described above, and description of similar matters will be omitted.

FIG. 10 is a diagram showing an example of an electronic component inspection device and an electronic component conveying device using the force detection device 1 (1a or 1b) according to the present invention. FIG. 11 is a diagram illustrating an example of an electronic component transport device using the force detection device according to the present invention.
The electronic component inspection apparatus 700 of FIG. 10 includes a base 710 and a support base 720 provided upright on the side surface of the base 710. On the upper surface of the base 710, an upstream stage 712u on which the electronic component 711 to be inspected is placed and transported, and a downstream stage 712d on which the inspected electronic component 711 is placed and transported are provided. ing. Further, between the upstream stage 712u and the downstream stage 712d, an imaging device 713 for confirming the posture of the electronic component 711, and an inspection table 714 on which the electronic component 711 is set for inspecting electrical characteristics. And are provided. Examples of the electronic component 711 include semiconductors, semiconductor wafers, display devices such as CLD and OLED, crystal devices, various sensors, inkjet heads, various MEMS devices, and the like.

  Further, the support base 720 is provided with a Y stage 731 that can move in a direction (Y direction) parallel to the upstream stage 712u and the downstream stage 712d of the base 710. An arm portion 732 is extended in a direction (X direction) toward 710. An X stage 733 is provided on the side surface of the arm 732 so as to be movable in the X direction. In addition, the X stage 733 is provided with an imaging camera 734 and an electronic component transfer device 740 incorporating a Z stage movable in the vertical direction (Z direction). In addition, a gripping portion 741 that grips the electronic component 711 is provided on the front end side of the electronic component transport apparatus 740. Further, the force detection device 1 (1a or 1b) according to the present invention is provided between the tip of the electronic component transport device 740 and the gripping portion 741. Further, on the front side of the base 710, a control device 750 for controlling the overall operation of the electronic component inspection device 700 is provided.

  The electronic component inspection apparatus 700 inspects the electronic component 711 as follows. First, the electronic component 711 to be inspected is placed on the upstream stage 712u and moved to the vicinity of the inspection table 714. Next, the Y stage 731 and the X stage 733 are moved to move the electronic component transport device 740 to a position immediately above the electronic component 711 placed on the upstream stage 712u. At this time, the position of the electronic component 711 can be confirmed using the imaging camera 734. Then, when the electronic component transport device 740 is lowered using the Z stage built in the electronic component transport device 740 and the electronic component 711 is gripped by the gripping portion 741, the electronic component transport device 740 is directly placed on the imaging device 713. The position of the electronic component 711 is confirmed using the imaging device 713. Next, the attitude of the electronic component 711 is adjusted using a fine adjustment mechanism built in the electronic component transport apparatus 740. Then, after moving the electronic component transport device 740 to above the inspection table 714, the Z stage built in the electronic component transport device 740 is moved to set the electronic component 711 on the inspection table 714. Since the attitude of the electronic component 711 is adjusted using the fine adjustment mechanism in the electronic component conveying apparatus 740, the electronic component 711 can be set at the correct position on the inspection table 714. Next, after the electrical characteristic inspection of the electronic component 711 is completed using the inspection table 714, the electronic component 711 is picked up from the inspection table 714, the Y stage 731 and the X stage 733 are moved, and the upper stage 712d is moved. The electronic component conveying device 740 is moved to the position, and the electronic component 711 is placed on the downstream stage 712d. Finally, the downstream stage 712d is moved to transport the electronic component 711 that has been inspected to a predetermined position.

  FIG. 11 is a diagram showing an electronic component transport device 740 including the force detection device 1 (1a or 1b) according to the present invention. The electronic component conveying device 740 is rotatable to a gripping portion 741, a force detection device 1 connected to the gripping portion 741, a rotation shaft 742 connected to the gripping portion 741 via the force detection device 1, and a rotation shaft 742. Has a fine adjustment plate 743 attached thereto. The fine adjustment plate 743 is movable in the X direction and the Y direction while being guided by a guide mechanism (not shown).

  Further, a piezoelectric motor 744θ for rotation direction is mounted toward the end surface of the rotation shaft 742, and a driving convex portion (not shown) of the piezoelectric motor 744θ is pressed against the end surface of the rotation shaft 742. Therefore, by operating the piezoelectric motor 744θ, the rotation shaft 742 (and the gripping portion 741) can be rotated by an arbitrary angle in the θ direction. Further, a piezoelectric motor 744 x for X direction and a piezoelectric motor 744 y for Y direction are provided toward the fine adjustment plate 743, and each drive convex portion (not shown) is a surface of the fine adjustment plate 743. It is pressed against. For this reason, by operating the piezoelectric motor 744x, the fine adjustment plate 743 (and the gripper 741) can be moved by an arbitrary distance in the X direction. Similarly, the fine adjustment can be performed by operating the piezoelectric motor 744y. The plate 743 (and the gripping portion 741) can be moved by an arbitrary distance in the Y direction.

  Further, the force detection device 1 has a function of detecting an external force applied to the grip portion 741. By feeding back the external force detected by the force detection device 1 to the control device 750, the electronic component transport device 740 and the electronic component inspection device 700 can perform work more precisely. Further, contact of the gripping portion 741 with an obstacle can be detected by an external force detected by the force detection device 1. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that were difficult with conventional position control can be easily performed, and the electronic component transport device 740 and the electronic component inspection device 700 can perform safer work. is there. Furthermore, since the force detection device 1 according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1 can be downsized. Therefore, the electronic component conveying device 740 and the electronic component inspection device 700 can be reduced in size.

<Seventh embodiment>
Next, based on FIG. 12, the component processing apparatus which is 7th Embodiment of this invention is demonstrated. Hereinafter, the seventh embodiment will be described with a focus on differences from the first, second, third, fourth, fifth, and sixth embodiments described above, and description of similar matters will be omitted. .
FIG. 12 is a diagram showing an example of a component processing apparatus using the force detection device 1 (1a or 1b) according to the present invention. The component processing apparatus 800 in FIG. 12 is attached to a base 810, a support column 820 that is erected on the upper surface of the base 810, a feed mechanism 830 that is provided on the side surface of the support column 820, and a feed mechanism 830 that can be moved up and down. A tool displacement unit 840, a force detection device 1 (1a or 1b) connected to the tool displacement unit 840, and a tool 850 attached to the tool displacement unit 840 via the force detection device 1.

  The base 810 is a base for mounting and fixing the workpiece 860. The column 820 is a column for fixing the feed mechanism 830. The feed mechanism 830 has a function of moving the tool displacement portion 840 up and down. The feed mechanism 830 includes a feed motor 831 and a guide 832 that raises and lowers the tool displacement portion 840 based on an output from the feed motor 831. The tool displacement unit 840 has a function of imparting displacement such as rotation and vibration to the tool 850. The tool displacement portion 840 includes a displacement motor 841, a tool attachment portion 843 provided at the tip of a main shaft (not shown) connected to the displacement motor 841, and a holder attached to the tool displacement portion 840 and holding the main shaft. Part 842. The tool 850 is attached to the tool attachment portion 843 of the tool displacement portion 840 via the force detection device 1 and is used for machining the workpiece 860 in accordance with the displacement given from the tool displacement portion 840. The tool 850 is not particularly limited, and is, for example, a wrench, a Phillips screwdriver, a flat-blade screwdriver, a cutter, a circular saw, a nipper, a cone, a drill, or a milling cutter.

  The force detection device 1 has a function of detecting an external force applied to the tool 850. By feeding back the external force detected by the force detection device 1 to the feed motor 831 and the displacement motor 841, the component processing device 800 can execute the component processing operation more precisely. Further, the contact of the tool 850 with an obstacle or the like can be detected by the external force detected by the force detection device 1. Therefore, an emergency stop can be performed when an obstacle or the like comes in contact with the tool 850, and the component processing apparatus 800 can execute a safer component processing operation. Furthermore, since the force detection device 1 according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1 can be downsized. Therefore, the component processing apparatus 800 can be reduced in size.

<Eighth Embodiment>
Next, based on FIG. 13, the moving body which is 8th Embodiment of this invention is demonstrated. Hereinafter, the eighth embodiment will be described with a focus on differences from the first, second, third, fourth, fifth, sixth, and seventh embodiments described above. Description is omitted.
FIG. 13 is a diagram showing an example of a moving body using the force detection device 1 (1a or 1b) according to the present invention. The moving body 900 in FIG. 13 can move with the applied power. The moving body 900 is not particularly limited, and is, for example, a vehicle such as an automobile, a motorcycle, an airplane, a ship, or a train, a robot such as a bipedal walking robot, or a wheeled robot.

The moving body 900 detects a main body 910 (for example, a vehicle casing, a robot main body, etc.), a power unit 920 that supplies power for moving the main body 910, and an external force generated by the movement of the main body 910. The force detection device 1 (1a or 1b) according to the present invention and a control unit 930 are included.
When the main body 910 is moved by the power supplied from the power unit 920, vibration, acceleration, and the like are generated with the movement. The force detection device 1 detects an external force caused by vibration, acceleration, or the like that occurs with movement. The external force detected by the force detection device 1 is transmitted to the control unit 930. The control unit 930 can execute control such as posture control, vibration control, and acceleration control by controlling the power unit 920 and the like according to the external force transmitted from the force detection device 1. Furthermore, since the force detection device 1 according to the present invention does not require a circuit for reducing output drift such as a reverse bias circuit, the force detection device 1 can be downsized. Therefore, the moving body 900 can be reduced in size.

The force detection device 1 (1a, 1b) according to the present invention can also be applied to various measuring devices such as a vibration meter, an accelerometer, a gravimeter, a dynamometer, a seismometer, or an inclinometer. Various measuring instruments using the force detection device 1 are also within the scope of the present invention.
In the force detection device 1 (1a, 1b) according to the present invention, the maximum detection load is 250 N, the maximum detection moment is 180 Nm, the minimum detection moment is 0.00016 Nm, the breaking load is 1000 N or more, and the hysteresis characteristic is 2% or less. High performance.

  As described above, the force detection device according to the present invention, and the robot, the electronic component transport device, the electronic component inspection device, the component processing device, and the moving body using the force detection device have been described based on the illustrated embodiments. The invention is not limited to this, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other component may be added to the present invention. In addition, the present invention may be a combination of any two or more configurations (features) of the embodiment.

DESCRIPTION OF SYMBOLS 1a, 1b ... Force detection apparatus 2 ... 1st base 21 ... 1st inclination part 3a, 3b ... Force detection element 4 ... 2nd base 41 ... 2nd inclination part 5 ... External force detection circuit 30a, 30b, 30c, 30d ... Force detection element 31 ... Charge output element 32, 32a, 32b, 32c ... Conversion circuit 33 ... Operational amplifier 34 ... Capacitor 35 ... Switching element 301a ... First charge output element 301b ... Second charge output element 310 ... Ground electrode layer 320: First β-axis sensor 321: First piezoelectric layer 322: Output electrode layer 323: Second piezoelectric layer 330: First γ-axis sensor 331: Third piezoelectric layer 332: Output Electrode layer 333 ... fourth piezoelectric layer 340 ... first α-axis sensor 341 ... fifth piezoelectric layer 342 ... output electrode layer 343 ... sixth piezoelectric layer 350 ... second β-axis Sensor 360 ... second γ-axis sensor 370 ... second α-axis sensor 50 ... external force detection circuit 500 ... single-arm robot 510 ... base 520 ... arm connector 521 ... first arm 522 ... second Arm 523 ... Third arm 524 ... Fourth arm 525 ... Fifth arm 530 ... End effector 531 ... First finger 532 ... Second finger 600 ... Multi-arm robot 610 ... Base 620 ... First arm Linked body 621 ... 1st arm 622 ... 2nd arm 630 ... 2nd arm linked body 631 ... 1st arm 632 ... 2nd arm 640a ... 1st end effector 641a ... 1st finger 642a ... 1st Second finger 640b ... second end effector 641b ... first finger 642b ... second finger 700 ... electronic component inspection device 710 ... base 71 ... Electronic components 712u ... Upstream stage 712d ... Downstream stage 713 ... Imaging device 714 ... Inspection table 720 ... Supporting table 731 ... Y stage 732 ... Arms 733 ... X stage 734 ... Imaging camera 740 ... Electronic component conveying device 741 ... Grip 742 ... Rotating shaft 743 ... Fine adjustment plate 744x, 744y, 744θ ... Piezoelectric motor 750 ... Control device 800 ... Part processing device 810 ... Base 820 ... Post 830 ... Feed mechanism 831 ... Feed motor 832 ... Guide 840 ... Tool displacement Numeral 841 ... Motor for displacement 842 ... Holding part 843 ... Tool mounting part 850 ... Tool 860 ... Work piece 900 ... Moving object 910 ... Main body 920 ... Power part 930 ... Control part A1, A2 ... Axis CA1 ... First crystal axis CA2 ... second crystal axis CA3 ... th Crystal axis CA4 ... fourth crystal axis CA5 ... fifth crystal axis CA6 ... sixth crystal axis Pα, Pα1, Pα2, Pα3, Pα4 ... polarization axes Pβ, Pβ1, Pβ2, Pβ3, Pβ4 ... polarization axes Pγ, Pγ1, Pγ2, Pγ3, Pγ4 ... Polarization axes Q, Q1, Q2, Qα, Qβ, Qγ ... Charge V1, V2, Vα, Vβ, Vγ ... Voltages θ1, θ2, θ3, θ4 ... Angle

Claims (13)

A first base;
A first element and a second element that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage;
A second base provided with at least the first element and the second element between the first base and
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, A force detection device, wherein a polarization axis of a charge output from one element and a polarization axis of a charge output from the second element are arranged in opposite directions.   The force detection device according to claim 1, wherein the force detection device calculates a difference between the voltages output from the first element and the second element.   3. The first element and the second element according to claim 1 or 2, wherein the polarization axis of the first element and the polarization axis of the sensor of the second element are on the same axis. The force detector described. The first element and the second element are:
It is configured by laminating a plurality of ground electrode layers grounded to the ground and three sensors having a polarization axis of charges output according to the external force,
The force detection device according to any one of claims 1 to 3, wherein the polarization axes of the sensors are orthogonal to each other. When the stacking direction of the sensors is the γ-axis direction, and the directions orthogonal to the γ-axis direction and orthogonal to each other are the α-axis direction and the β-axis direction,
One of the sensors is an α-axis sensor that outputs the electric charge according to the external force in the α-axis direction,
One of the sensors is a β-axis sensor that outputs the electric charge according to the external force in the β-axis direction,
The force detection device according to claim 4, wherein one of the sensors is a γ-axis sensor that outputs the electric charge according to the external force in the γ-axis direction. The force detection device includes two first elements and two second elements,
The direction of the polarization axis of one of the first elements and one of the second elements is the direction of the polarization axis of the other first element and the other of the second element. Facing the direction opposite to the direction of the polarization axis of
The direction of the polarization axis of the γ-axis sensor of the one first element and the one second element is the γ-axis sensor of the other first element and the other second element. The force detection device according to claim 5, wherein the force detection device faces in a direction opposite to a direction of the polarization axis. The sensor is
A first piezoelectric layer having a first crystal axis;
A second piezoelectric layer provided opposite to the first piezoelectric layer and having a second crystal axis;
An output electrode layer provided between the first piezoelectric layer and the second piezoelectric layer;
The direction of the first crystal axis of the first piezoelectric layer is directed in a direction opposite to the direction of the second crystal axis of the second piezoelectric layer. The force detection device according to item.   The force detection device according to claim 7, wherein the first piezoelectric layer and the second piezoelectric layer are made of quartz.   9. The force detection device according to claim 1, wherein the elements are arranged at equiangular intervals in the circumferential direction of the first base or the second base. A plurality of arms, and at least one arm connecting body formed by rotatably connecting the adjacent arms of the plurality of arms;
An end effector provided on a distal end side of the arm coupling body;
A force detection device provided between the arm coupling body and the end effector and detecting an external force applied to the end effector;
The force detection device includes:
A first base;
A first element and a second element that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage;
A second base provided with at least the first element and the second element between the first base and
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The robot is characterized in that the polarization axis of the charge output from one element and the polarization axis of the charge output from the second element are arranged in opposite directions. A gripper for gripping electronic components;
A force detection device that detects an external force applied to the gripping portion;
The force detection device includes:
A first base;
A first element and a second element that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage;
A second base provided with at least the first element and the second element between the first base and
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, An electronic component transport apparatus, wherein a polarization axis of charge output from one element and a polarization axis of charge output from the second element are arranged to face in opposite directions. A gripper for gripping electronic components;
An inspection unit for inspecting the electronic component;
A force detection device that detects an external force applied to the gripping portion;
The force detection device includes:
A first base;
A first element and a second element that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage;
A second base provided with at least the first element and the second element between the first base and the first base. The first element and the second element include the first base and the second base. Two tilted or perpendicular to the two bases, having a polarization axis of charge output according to the external force,
An electronic component inspection apparatus, wherein the polarization axis of the charge output from the first element and the polarization axis of the charge output from the second element are arranged to face in opposite directions. A tool displacing part for mounting the tool and displacing the tool;
A force detection device for detecting an external force applied to the tool;
The force detection device includes:
A first base;
A first element and a second element that convert an electric charge output according to an external force into a voltage and detect the external force from the voltage;
A second base provided with at least the first element and the second element between the first base and
The first element and the second element are arranged to be inclined or perpendicular to the first base part and the second base part, and have a polarization axis of a charge output according to the external force, The component processing apparatus, wherein the polarization axis of the charge output from the first element and the polarization axis of the charge output from the second element are arranged in opposite directions.

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