JP2014163870A - Force detection device, robot, electronic component transport device, electronic component inspection device, component processing device and moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force detection device in which an output drift is reduced and the size is reduced, a robot using the force detection device, an electronic component transport device, an electronic component inspection device, a component processing device and a moving body.SOLUTION: A force detection device 1a includes: a first element 3a and a second element 3b for outputting a voltage according to an external force; and an external force detection circuit for detecting the external force on the basis of the voltage output from the first element 3a and the second element 3b. The first element 3a and the second element 3b have: a sensor having polarization axes Pβ1 and Pβ2, and outputting charges according to the external force along the polarization axes Pβ1 and Pβ2; and a conversion circuit for converting the charges output from the sensor to a voltage. The first element 3a and the second element 3b are arranged in such a manner that the direction of the polarization axis Pβ1 which the sensor of the first element 3a has and the direction of the polarization axis Pβ2 which the sensor of the second element 3b has face the opposite directions mutually.

Description

  The present invention relates to a force detection device, and a robot, an electronic component conveying device, an electronic component inspection device, a component processing device, and a moving body 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 the direction of one axis or a plurality of axes, a hand attached to the tip of the arm, an end effector such as a component inspection instrument, a component transport instrument, 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 aims at providing a conveying apparatus, an electronic component inspection apparatus, a component processing apparatus, and a moving body.

Such an object is achieved by the following invention.
The force detection device of the present invention is configured to output the external force based on the first element and the second element that output a voltage according to an external force, and the voltage output from the first element and the second element. An external force detection circuit to detect,
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.

  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.

In the force detection device of the present invention, the external force detection unit detects the external force applied to the force detection device by taking a difference between the voltages output from the first element and the second element. It is preferable to do.
Thereby, the detection error resulting from output drift can be reduced.
In the force detection device of the present invention, the first element and the second element may include a direction of the polarization axis of the sensor of the first element and a direction of the polarization axis of the sensor of the second element. It is preferable that the directions face each other on the same axis.
As a result, the external force can be detected while further reducing the output drift.

In the force detection device of the present invention, the first element and the second element are:
Preferably, a plurality of ground electrode layers that are grounded to the ground and the three sensors are stacked, and the polarization axes of the sensors are orthogonal to each other.
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).

In the force detection device of 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 along the α-axis direction,
One of the sensors is a β-axis sensor that outputs the electric charge according to the external force along the β-axis direction,
One of the sensors is preferably a γ-axis sensor that outputs the electric charge according to the external force along 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).

The force detection device of 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.

In the force detection device of the present invention, the sensor is provided with a first piezoelectric layer having a first crystal axis and a second piezoelectric axis provided opposite to the first piezoelectric layer and having a second crystal axis. A piezoelectric layer, 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.
In the force detection device of 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.

The force detection device of the present invention preferably further includes a base plate and a cover plate facing the base plate, and each of the elements is provided between the base plate and the cover plate.
Thereby, an external force applied to the base plate or the cover plate can be detected.
In the force detection device of the present invention, it is preferable that the elements are arranged at equiangular intervals along the circumferential direction of the base plate or the cover plate.
Thereby, an external force can be detected without deviation.

The robot of 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 the 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 detects the external force based on the first element and the second element that output a voltage according to the external force, and the voltage output from the first element and the second element. An external force detection circuit that
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.

  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.

An electronic component conveying device of 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 detects the external force based on the first element and the second element that output a voltage according to the external force, and the voltage output from the first element and the second element. An external force detection circuit that
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.

  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.

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 detects the external force based on the first element and the second element that output a voltage according to the external force, and the voltage output from the first element and the second element. An external force detection circuit that
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.

  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.

The component processing apparatus of 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 detects the external force based on the first element and the second element that output a voltage according to the external force, and the voltage output from the first element and the second element. An external force detection circuit that
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.

  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.

The moving body of the present invention includes a power unit that supplies power for movement, and a force detection device that detects an external force generated by the movement,
The force detection device detects the external force based on the first element and the second element that output a voltage according to the external force, and the voltage output from the first element and the second element. An external force detection circuit that
The first element and the second element are:
A sensor that has a polarization axis, and outputs a charge according to the external force along the polarization axis; and a conversion circuit that converts the charge output from the sensor into the voltage.
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arrange | positioned so that it may face.
As a result, the force detection device can detect an external force caused by vibration, acceleration, or the like that is caused by movement, and the moving body can execute control such as posture control, vibration control, and acceleration control. 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 moving body can be reduced in size.

It is the perspective view and top view which show schematically 1st Embodiment of the force detection apparatus of this 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 top view which show schematically 2nd Embodiment of the force detection apparatus of this invention. FIG. 5 is a circuit diagram schematically showing the force detection device shown in FIG. 4. FIG. 5 is a cross-sectional view schematically showing a charge output element of the force detection device shown in FIG. 4. It is a figure which shows an example of the single arm robot using the force detection apparatus of this invention. It is a figure which shows an example of the multi-arm robot using the force detection apparatus of this invention. It is a figure which shows an example of the electronic component inspection apparatus and electronic component conveyance apparatus using the force detection apparatus of this invention. It is a figure which shows one example of the electronic component conveying apparatus using the force detection apparatus of this invention. It is a figure which shows one example of the component processing apparatus using the force detection apparatus of this invention. It is a figure which shows one example of the moving body using the force detection apparatus of this invention.

Hereinafter, the force detection device of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.
<First Embodiment>
FIG. 1A is a perspective view schematically showing a first embodiment of the force detection device of the present invention. FIG.1 (b) is a top view which shows roughly 1st Embodiment of the force detection apparatus of this invention. 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.

  A force detection device 1a shown in FIG. 1 has a function of detecting a shear force (external force along the x-axis and y-axis in FIG. 1). The force detection device 1a includes a base plate 2, a cover plate 4 facing the base plate 2, and a force detection element (element) that is sandwiched (provided) between the base plate 2 and the cover plate 4 and outputs a voltage according to an external force. ) 3a, 3b, and an external force detection circuit 5 (not shown in FIG. 1; see FIG. 2) for detecting an external force based on the voltage output from each of the force detection elements 3a, 3b.

<Force detection element (element)>
The force detection elements 3a and 3b shown in FIG. 1 have a function of outputting a voltage V in accordance with an applied shear force (external force along the x-axis and y-axis in FIG. 1).
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, 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. That is, the β-axis sensor 320 has a polarization axis Pβ that faces the positive direction of the β-axis.
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 includes an external force detection circuit that detects an external force based on force detection elements (elements) 3a and 3b forming a pair of elements and voltages V1 and V2 output from the force detection elements 3a and 3b, respectively. 5 can be used 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 FIG. 1B, the cover plate 4 is omitted for explanation. In FIG. 1B, the left-right direction is the x-axis direction, and the direction orthogonal to the x-axis direction, that is, the up-down direction is the y-axis direction.
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 3 a and 3 b are provided (sandwiched) between the base plate 2 and the cover plate 4. The polarization axis Pβ1 of the force detection element 3a has an angle θ1. Similarly, the polarization axis Pβ2 of the force detection element 3b has an angle θ2. The angles θ1 and θ2 are angles from the x axis of the reference coordinate system (x axis, y axis) in FIG.

  As shown in FIG. 1B, the force detection elements 3a and 3b are arranged so that the direction of the polarization axis Pβ1 of the force detection element 3a and the direction of the polarization axis Pβ2 of the force detection element 3b are opposite to each other. Has been. “Directing in opposite directions” here means that the direction of the polarization axis Pβ1 and the direction 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. At least when each of the polarization axis Pβ1 and the polarization axis Pβ2 is decomposed into a vector component in the orthogonal 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 and the x-axis of the polarization axis Pβ2 The vector component in the direction may be in the reverse 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 reverse direction.

  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 direction of the polarization axis Pβ1 and the direction 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.
The arrangement of the force detection elements 3a and 3b is not particularly limited as long as the direction of the polarization axis Pβ1 of the force detection element 3a and the direction of the polarization axis Pβ2 of the force detection element 3b are opposite to each other. However, 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. Thereby, the shearing force applied to the base plate 2 or the cover plate 4 (external forces along the x-axis and y-axis in the figure) can be detected without deviation.

Moreover, although the polarization axis Pβ1 of the force detection element 3a and the polarization axis Pβ2 of the force detection element 3b in FIG. 1B face the outside (centrifugal direction) of the base plate 2, the present invention is not limited to this. That is, if the direction of the polarization axis Pβ1 of the force detection element 3a and the direction of the polarization axis Pβ2 of the force detection element 3b are arranged so as to be opposite to each other, the polarization axis Pβ1 of the force detection element 3a and the force detection element The polarization axis Pβ2 of 3b may face the center direction (centrecent direction) of the base plate 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.

  Further, the force detection elements 3a and 3b are arranged so that the direction of the polarization axis Pβ1 of the force detection element 3a and the direction of the polarization axis Pβ2 of the force detection element 3b are opposite to each other. The signs of the voltage component Vt1 included and the voltage component Vt2 included in the 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.

  On the other hand, since the output drift D included in the voltage V1 and the output drift D included in the voltage V2 do not depend on the directions of the polarization axes Pβ1 and Pβ2, the sign of the output drift D included in the voltage V1 and the voltage V2 are included. The sign of the output drift D to be matched. 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 output drift D included in the voltage V1 and the output drift D included in the voltage V2 The absolute value of the difference decreases.

<External force detection circuit>
The external force detection circuit 5 takes the difference between the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b, thereby applying a shear force (x in the figure) to the force detection device 1a. And an external force along the y-axis).
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.

Thus, 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 absolute value of the output drift D decreases. Therefore, the output drift D can be reduced. As a result, the detection error due to the leakage current (output drift D) becomes relatively small, and the detection accuracy and detection resolution 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.
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 direction of the polarization axis Pβ1 and the direction of the polarization axis Pβ2 face each other, Fx, The calculation formula of Fy is simplified and becomes as follows.

In this case, the output drift D can be removed (further reduced). As a result, the detection accuracy and detection resolution 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 includes a force detection element arranged such that the direction of the polarization axis Pβ1 of the force detection element 3a and the direction of the polarization axis Pβ2 of the force detection element 3b are opposite to each other. 3a, 3b, an external force detection circuit that detects a shear force applied to the force detection device 1a by taking the difference between the voltage V1 output from the force detection element 3a and the voltage V2 output from the force detection element 3b. Therefore, 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 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 of 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.
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. 4, FIG. 5, and 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 of the present invention. FIG. 4B is a plan view schematically showing a second embodiment of the force detection device of the present invention. FIG. 5 is a circuit diagram schematically showing the force detection device shown in FIG. FIG. 6A is a cross-sectional view schematically showing the charge output element of the first force detection device shown in FIG. FIG. 6B 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. 4 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 provided (sandwiched) between the base plate 2, the cover plate 4 facing the base plate 2, and the base plate 2 and the cover plate 4, and outputs voltages Vα, Vβ, and Vγ according to the external force. An external force detection circuit 50 that detects six-axis forces based on the voltages Vα, Vβ, and Vγ output from the force detection elements (elements) 30a, 30b, 30c, and 30d and the force detection elements 30a, 30b, 30c, and 30d, respectively. (Not shown in FIG. 4, refer to FIG. 5).

<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. 5, the force detection elements 30a and 30c belonging to the first element pair have a charge Qα according to the external force applied along the 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. 6A 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. 6A, 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 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 an external force (shear) parallel to the α-axis The first α-axis sensor 340 outputs a charge Qα according to the force), and the ground electrode layer 310 and the sensors 320, 330, and 340 are alternately stacked. In FIG. 6, the stacking direction of the ground electrode layer 310 and 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 configuration shown in FIG. 6, the 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. Not limited. The stacking order of the sensors 320, 330, and 340 is arbitrary.
The β-axis sensor 320 has a function of outputting a charge Qβ according to an external force (shearing force) parallel to the β-axis. The 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 has a polarization axis Pγ that faces the positive direction of the γ-axis in FIG.

  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. That is, the first α-axis sensor 340 has a polarization axis Pα that faces the positive direction of the α-axis in FIG.

  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 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 β-axis sensor 320 and the polarization axis of the first γ-axis sensor 330. The layers are stacked so that the direction of Pγ and the direction of the polarization axis Pα of the first α-axis sensor 340 are 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. 6B 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. 6B, 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 β-axis sensor 320 that outputs a charge Qβ, a second γ-axis sensor 350 that outputs a charge Qγ in response to an external force (compression / tensile force) parallel to the γ-axis, and an external force (shear) parallel to the α-axis The ground electrode layer 310 and the sensors 320, 350, and 360 are alternately stacked. Accordingly, the second charge output element 301b includes a second γ-axis sensor 350 having a structure different from that of the first γ-axis sensor 330 and a second α-axis having a structure different from that of the first α-axis sensor 340. The structure is the same as that of the first charge output element 301a except that the sensor 360 is provided. In FIG. 6, the stacking direction of the ground electrode layer 310 and each of the sensors 320, 350, and 360 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 β-axis direction.
In the configuration shown in FIG. 6, the β-axis sensor 320, the second γ-axis sensor 350, and the second α-axis sensor 360 are stacked in this order from the lower side in FIG. Not limited. The stacking order of each sensor 320, 350, 360 is arbitrary.

  The second γ-axis sensor 350 has a function of outputting an electric charge Qγ according to an external force (compression / tensile force) parallel to the γ-axis. The second γ-axis sensor 350 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 350 has a polarization axis Pγ that faces the negative direction of the γ-axis in FIG. Therefore, the direction of the polarization axis Pγ of the second γ-axis sensor 350 is opposite to the direction of the polarization axis Pγ of the first γ-axis sensor 330.

  The second γ-axis sensor 350 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 layers constituting the second γ-axis sensor 350 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 350 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 360 has a function of outputting a charge Qα according to an external force (shearing force) parallel to the α-axis. The second α-axis sensor 360 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 360 has a polarization axis Pα that faces the negative direction of the α-axis in FIG. Therefore, the direction of the polarization axis Pα of the second α-axis sensor 360 is opposite to the direction of the polarization axis Pα of the first α-axis sensor 340.

  The second α-axis sensor 360 is provided opposite to 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. In addition, the stacking order of the layers constituting the second α-axis sensor 360 is the order of the sixth piezoelectric layer 343, the output electrode layer 342, and the fifth piezoelectric layer 341 from the lower side in FIG. is there. Therefore, the second α-axis sensor 360 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 β-axis sensor 320, the second γ-axis sensor 350, and the second α-axis sensor 360 are the direction of the polarization axis Pβ of the β-axis sensor 320 and the polarization axis of the second γ-axis sensor 350. The layers are laminated so that the direction of Pγ and the direction of the polarization axis Pα of the second α-axis sensor 360 are orthogonal to each other. The direction of the polarization axis Pγ of the second γ-axis sensor 350 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 360 is opposite to the direction of the polarization axis Pα of the first α-axis sensor 340.

  In addition, the charge generation amount per unit force of the β-axis sensor 320, the first α-axis sensor 340, and the second α-axis sensor 360 formed of Y-cut quartz 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 350 constituted by 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, the positional relationship between 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 will be described in detail with reference to FIG. In FIG. 4B, the cover plate 4 is omitted for explanation. 4B, the left-right direction is the x-axis direction, the direction orthogonal to the x-axis direction, that is, the up-down 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.

  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 provided (sandwiched) between the base plate 2 and the cover plate 4. The polarization axis Pβ1 of the force detection element 30a has an angle θ1. The polarization axis Pβ2 of the force detection element 30b has an angle θ2. The polarization axis Pβ3 of the force detection element 30c has an angle θ3. The polarization axis Pβ4 of the force detection element 30d has an 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.

  As shown in FIG. 4 (b), the force detection elements 30a and 30c forming the first element pair include the directions of the polarization axes Pα1 and Pβ1 of the force detection element 30a and the polarization axes Pα3 and Pβ3 of the force detection element 30c. The directions are arranged in opposite directions. Similarly, in the force detection elements 30b and 30d forming the second element pair, the directions of the polarization axes Pα2 and Pβ2 of the force detection element 30b and the directions of the polarization axes Pα4 and Pβ4 of the force detection element 30d are opposite to each other. It is arranged to face the direction. Also, the directions of the polarization axes Pγ1 and Pγ3 of the force detection elements 30a and 30c forming the first element pair and the directions of the polarization axes Pγ2 and Pγ4 of the force detection elements 30b and 30d forming the second element pair are mutually It faces the opposite direction.

  Since the force detection elements 30a and 30c are arranged such that the direction of the polarization axis Pβ1 of the force detection element 30a and the direction of the polarization axis Pβ2 of the force detection element 30c are opposite to each other, they are included in the voltage Vβ1. The signs of the voltage component Vβt1 and the voltage component Vβt3 included in the voltage Vβ3 do not match. Therefore, when the difference between the voltage Vβ1 output from the force detection element 30a and the voltage Vβ3 output from the force detection element 30c is taken, the absolute value of the difference between the voltage component Vβt1 and the voltage component Vβt3 does not decrease. Similarly, the force detection elements 30a and 30c are arranged such that 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. The sign of the voltage component Vαt1 included in the voltage Vαt3 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, the force detection elements 30b and 30d are arranged so that the direction of the polarization axis Pβ2 of the force detection element 30b and the direction of the polarization axis Pβ4 of the force detection element 30d are opposite to each other. The signs of the voltage component Vβt2 included and the voltage component Vβt4 included in the voltage Vβ4 do not match. Therefore, when the difference between the voltage Vβ2 output from the force detection element 30b and 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, the force detection elements 30b and 30d are arranged such that 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. The sign of the voltage component Vαt2 included in the voltage Vαt4 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.

  In addition, as described above, the force detection elements 30a, 30c, 30b, and 30d have the directions of the polarization axes Pγ1 and Pγ3 of the force detection elements 30a and 30c and the directions of the polarization axes Pγ2 and Pγ4 of the force detection elements 30b and 30d. Since they are configured to face in opposite directions, the signs of the voltage components Vγt1 and Vγt3 included in the voltages Vγ1 and Vγ3 and the voltage components Vγt2 and Vγt4 included in the voltages Vγ2 and Vγ4 do not match. Therefore, when the difference between the voltages Vγ1 and Vγ3 output from the force detection elements 30a and 30c and the voltages Vγ2 and Vγ4 output from the force detection elements 30b and 30d is taken, the absolute value of the difference 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 preferably arranged so that the direction of the polarization axis Pβ1 and the direction of the polarization axis Pβ3 face each other, that is, satisfy the relationship θ1 = θ3. . Similarly, the force detection elements 30b and 30d constituting the second element pair are arranged so that the direction of the polarization axis Pβ2 and the direction of the polarization axis Pβ4 face each other, that is, satisfy the relationship of θ2 = θ4. 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 include the directions of the polarization axes Pβ1 and Pβ3 of the force detection elements 30a and 30c that constitute the first element pair, and the force detection element 30b that constitutes the second element pair. , 30d is more preferably arranged so that the directions of the polarization axes Pβ2 and Pβ4 are 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 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 arranged so as to be opposite to each other, the force detection element 30a forming the first element pair, Although arrangement | positioning of 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 direction of the polarization axis Pβ2 of the force detection element 30b and the direction of the polarization axis Pβ4 of the force detection element 30d are arranged so as to be opposite to each other, the force detection element 30b forming the second element pair will be described. 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. 4B. Thereby, the 6-axis force applied to the base plate 2 or the cover plate 4 can be detected without deviation.

  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 axis A1 connecting the center of 30c and the axis A2 connecting the center of the force detecting element 30b belonging to the second element pair and the center of the force detecting element 30d are orthogonal to each other. It is preferable to arrange element pairs. Thereby, the external force applied to the base plate 2 or the cover plate 4 (external forces along the x-axis, y-axis, and z-axis in the figure) can be detected without deviation.

  The force detection elements 30 a, 30 b, 30 c, and 30 d are preferably arranged at equiangular intervals along the circumferential direction of the base plate 2 or the cover plate 4, and are centered on the center point of the base plate 2 or the cover plate 4. More preferably, they are arranged in a concentric circle at regular intervals. Thereby, the external force applied to the base plate 2 or the cover plate 4 (external forces along the x-axis, y-axis, and z-axis in the figure) can be detected without deviation.

  4B, the polarization axes Pβ1, Pβ2, Pβ3, and Pβ4 of the force detection elements 30a, 30b, 30c, and 30d face the outside (centrifugal direction) of the base plate 2, but the present invention It 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, Pβ2, Pβ3, and Pβ4 of the force detection elements 30a, 30b, 30c, and 30d are arranged so that the directions of the polarization axes Pβ4 are opposite to each other, Direction). Thus, the polarization axes Pα1, Pα2, Pα3, and Pα4 of the force detection elements 30a, 30b, 30c, and 30d are directed in the tangential direction of the circle with the center point of the base plate 2 as the center. Therefore, the external force detection circuit 50 described later can easily detect the rotational force component Mz around the z axis.

<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 are concentric with a radius L with the center point of the base plate 2 or the cover plate 4 as shown in FIG. 4B. Although it shall be arrange | positioned, this invention is not limited to this.

Here, L is a constant.
Thus, by taking the difference between the voltages Vα, Vβ, and Vγ output from the force detection elements 30a, 30b, 30c, and 30d, a voltage component (true value) proportional to the amount of charge accumulated in the capacitor 34 is obtained. ) The absolute value of the difference between Vαt, Vβt, and Vγt is not 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, 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.

  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, the force detection device 1b of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, and thus the force detection device 1b can be reduced in size.

  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. 4B, by a very simple operation as described above. 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.

<Third Embodiment>
Next, based on FIG. 7, the single arm robot which is 3rd Embodiment of this invention is demonstrated. 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. 7 is a diagram showing an example of a single-arm robot using the force detection device 1 (1a or 1b) of the present invention. The single-arm robot 500 of FIG. 7 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 the arm coupling body 520 and the end effector 530. And the force detection device 1 (1a or 1b) of 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, the force detection device 1 of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, so that 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.

<Fourth embodiment>
Next, a multi-arm robot according to a fourth embodiment of the present invention will be described with reference to FIG. Hereinafter, the fifth 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 multi-arm robot using the force detection device 1 (1a or 1b) of the present invention. The multi-arm robot 600 of FIG. 8 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 It has the force detection apparatus 1 (1a or 1b) of this invention provided between the 2nd 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, the force detection device 1 of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, so that 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.

<Fifth Embodiment>
Next, based on FIGS. 9 and 10, an electronic component inspection apparatus and an electronic component transport apparatus according to a fifth embodiment of the present invention will be described. 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 an electronic component inspection device and an electronic component transport device using the force detection device 1 (1a or 1b) of the present invention. FIG. 10 is a diagram showing an example of an electronic component transport apparatus using the force detection device of the present invention.

  The electronic component inspection apparatus 700 in FIG. 9 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) of 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. 10 is a diagram showing an electronic component transport device 740 including the force detection device 1 (1a or 1b) of 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, the force detection device 1 of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, so that 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.

<Sixth Embodiment>
Next, based on FIG. 11, the component processing apparatus which is 6th Embodiment of this invention is demonstrated. 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. 11 is a diagram showing an example of a component processing apparatus using the force detection device 1 (1a or 1b) of the present invention. The component processing apparatus 800 in FIG. 11 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 a side surface of the support column 820, and a lift mechanism that can be moved up and down. A tool displacement portion 840, a force detection device 1 (1a or 1b) of the present invention connected to the tool displacement portion 840, and a tool 850 attached to the tool displacement portion 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, the force detection device 1 of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, so that the force detection device 1 can be downsized. Therefore, the component processing apparatus 800 can be reduced in size.

<Seventh embodiment>
Next, based on FIG. 12, the moving body 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 moving body using the force detection device 1 (1a or 1b) of the present invention. The moving body 900 of FIG. 12 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. It has the force detection device 1 (1a or 1b) of the present invention and a control unit 930.
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, the force detection device 1 of the present invention does not require a circuit for reducing output drift, such as a reverse bias circuit, so that 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) of 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 apparatus 1 are also within the scope of the present invention.

  The force detection device of the present invention and the robot, electronic component transport device, electronic component inspection device, component processing device, and moving body using the force detection device have been described based on the illustrated embodiments. However, the configuration of each unit can be replaced with any configuration having the same 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 1, 1a, 1b ... Force detection apparatus 2 ... Base plate 3a, 3b ... Force detection element 4 ... Cover plate 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 ... Sensor for beta axis 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 use Sensor 341: Fifth piezoelectric layer 342: Output electrode layer 343: Sixth piezoelectric layer 350: Second γ-axis sensor 360: Second α-axis Sensor 50 ... External force detection circuit 500 ... Single arm robot 510 ... Base 520 ... Arm coupling body 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 connector 621 ... First arm 622 ... Second arm 630 ... Second Arm coupling body 631 ... 1st arm 632 ... 2nd arm 640a ... 1st end effector 641a ... 1st finger 642a ... 2nd finger 640b ... 2nd end effector 641b ... 1st finger 642b ... 1st Second finger 700 ... Electronic component inspection device 710 ... Base 711 ... Electronic component 712u ... Upstream side stage 712d ... Downstream side Stage 713 ... Imaging device 714 ... Inspection table 720 ... Supporting table 731 ... Y stage 732 ... Arm part 733 ... X stage 734 ... Imaging camera 740 ... Electronic component transport device 741 ... Grasping part 742 ... Rotating shaft 743 ... Fine adjustment plate 744x, 744y, 744θ ... piezoelectric motor 750 ... control device 800 ... part processing device 810 ... base 820 ... support 830 ... feed mechanism 831 ... feed motor 832 ... guide 840 ... tool displacement portion 841 ... displacement motor 842 ... holding portion 843 ... Tool mounting part 850 ... Tool 860 ... Work piece 900 ... Moving body 910 ... Main body 920 ... Power part 930 ... Control part A1, A2 ... Axis CA1 ... First crystal axis CA2 ... Second crystal axis CA3 ... Third Crystal axis CA4 ... Fourth crystal axis CA5 ... Fifth crystal axis C 6 ... Sixth crystal axis Pα, Pα1, Pα2, Pα3, Pα4 ... Polarization axis Pβ, Pβ1, Pβ2, Pβ3, Pβ4 ... Polarization axis Pγ, Pγ1, Pγ2, Pγ3, Pγ4 ... Polarization axes Q, Q1, Q2, Qα , Qβ, Qγ: Charge V1, V2, Vα, Vβ, Vγ: Voltage θ1, θ2, θ3, θ4… Angle

Claims (15)

A first element and a second element that output a voltage in response to an external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. It is arranged to face the force detection device.   The force according to claim 1, wherein the external force detection unit detects the external force applied to the force detection device by taking a difference between the voltages output from the first element and the second element. Detection device.   In the first element and the second element, the direction of the polarization axis of the sensor of the first element and the direction of the polarization axis of the sensor of the second element are on the same axis. The force detection device according to claim 1, which faces each other. The first element and the second element are:
It is constituted by laminating a plurality of ground electrode layers grounded to the ground and the three sensors.
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 along the α-axis direction,
One of the sensors is a β-axis sensor that outputs the electric charge according to the external force along 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 along 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. The force detection device further includes a base plate and a cover plate facing the base plate,
The force detection device according to any one of claims 1 to 8, wherein each of the elements is provided between the base plate and the cover plate.   The force detection device according to claim 9, wherein the elements are arranged at equiangular intervals along a circumferential direction of the base plate or the cover plate. 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 element and a second element that output a voltage according to the external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. A robot characterized by being arranged to face. 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 element and a second element that output a voltage according to the external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. An electronic component conveying device, wherein the electronic component conveying device is arranged so as to face. 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 element and a second element that output a voltage according to the external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. An electronic component inspection apparatus characterized by being arranged so as to face. 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 element and a second element that output a voltage according to the external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. A component processing apparatus, which is arranged so as to face. A power unit for supplying power for movement;
A force detection device for detecting an external force generated by the movement,
The force detection device includes:
A first element and a second element that output a voltage according to the external force;
An external force detection circuit that detects the external force based on the voltage output from the first element and the second element;
The first element and the second element are:
A sensor having a polarization axis and outputting a charge according to the external force along the polarization axis;
A conversion circuit that converts the charge output from the sensor into the voltage;
In the first element and the second element, the direction of the polarization axis of the sensor of the first element is opposite to the direction of the polarization axis of the sensor of the second element. A moving object characterized by being arranged to face.

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