JP2017062260A - Force detection device and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized force detection device having output drift reduced, and a robot using the force detection device, an electronic component transportation device and an electronic component inspection device.SOLUTION: A force detection device 1a comprises: an element 10a outputting electric charge Q in response to external force received; a conversion output circuit 20 having a first switching element 23 and a first capacitor 22, converting the electric charge Q into a voltage V and outputting the voltage; a signal output circuit for compensation 30 having a second switching element 33 and a second capacitor 32 and outputting a signal for compensation Voff; and an external force detection circuit 40a detecting the external force based on the voltage V output from the conversion output circuit 20 and the signal for compensation Voff output from the signal output circuit for compensation 30. Capacitance of the second capacitor 32 is less than capacitance of the first capacitor 22.SELECTED DRAWING: Figure 1

Description

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

  In recent years, industrial robots have been introduced into production facilities such as factories for the purpose of improving production efficiency. Such an industrial robot includes an arm that can be driven in the direction of one axis or a plurality of axes, and an end effector such as a hand, a component inspection device, or a component transfer device, which is attached to the tip of the arm. Parts manufacturing work such as parts assembly work, parts processing work, parts transport work, parts inspection work, etc. can be executed.

  In such an industrial robot, a force detection device is provided between the arm and the end effector. As a force detection device used for an industrial robot, for example, a force detection device disclosed in Patent Document 1 is used. The force detection device of Patent Document 1 includes a charge output element (piezoelectric element) that outputs charges according to an external force received, an amplifier that amplifies charges output from the charge output elements, and charges output from the charge output elements. And a reset circuit having a mechanical relay for short-circuiting between the terminals of the capacitor and resetting the electric charge accumulated in the capacitor. By having such a configuration, the force detection device of Patent Literature 1 can detect an external force applied to the charge output element along an arbitrary axis.

  However, in order to control the end effector of an industrial robot, it is necessary to detect six-axis forces (that is, translational force components in the x, y, and z directions and rotational force components around the x, y, and z axes). There is a case. In such a case, a triaxial force detection device that can detect a triaxial force (translation force in the x, y, and z axis directions) by combining at least three force detection devices as disclosed in Patent Document 1 is configured. Therefore, it is necessary to mount the three-axis force detection device on a list of at least three industrial robots.

  If the size of the force detection device mounted on the list of such industrial robots is large, the operating area of the list may be narrowed. In addition, if the size of the force detection device is thick, the distance from the joint portion of the industrial robot to the end of the end effector becomes long, so that the portable weight of the industrial robot may be reduced. Therefore, the force detection device is preferably small and lightweight.

  In order to solve such a problem, various methods have been proposed. For example, Patent Document 2 discloses a force detection device using a semiconductor switching element as a reset circuit. Since the semiconductor switching element is smaller and lighter than the mechanical relay, the whole apparatus can be reduced in size and weight by using the semiconductor switching element as the reset circuit.

  However, when a semiconductor switching element is used as the reset circuit, output drift due to a leakage current of the semiconductor switching element occurs. Such output drift is not preferable because it lowers the detection resolution and detection accuracy of the force detection device. Furthermore, since the output drift is accumulated in proportion to the measurement (operation) time of the force detection device, there is a problem that the measurable time of the force detection device cannot be increased.

JP-A-5-95237 JP-A-11-148878

  The present invention has been made in view of the above circumstances, and provides a small-sized force detection device with reduced output drift, and a robot, an electronic component conveying device, and an electronic component inspection device using the force detection device. With the goal.

Such an object is achieved by the following invention.
The force detection device of the present invention includes an element that outputs electric charge according to the received external force, a first switching element, and a first capacitor, and converts the electric charge into a voltage and outputs the voltage. A compensation signal output circuit that has a conversion output circuit, a second switching element, and a second capacitor and outputs a compensation signal, the voltage output from the conversion output circuit, and the compensation signal An external force detection circuit that detects the external force based on the compensation signal output from the output circuit;
The capacitance of the second capacitor is smaller than the capacitance of the first capacitor.

  Thereby, the voltage output from the conversion output circuit can be compensated using the compensation signal output from the compensation signal output circuit. As a result, more accurate force detection can be performed. Further, since the capacitance of the second capacitor is smaller than the capacitance of the first capacitor, the compensation signal output circuit can acquire the compensation signal from the second switching element more accurately. As a result, the voltage output from the conversion output circuit can be compensated more accurately.

In the force detection device of the present invention, C2 / C1 is 0.1 to 0.8, where C1 is the capacitance of the first capacitor and C2 is the capacitance of the second capacitor. It is preferable.
When the capacitance ratio C2 / C1 falls below the lower limit value, the second capacitor may be saturated. On the other hand, if the capacitance ratio C2 / C1 exceeds the upper limit value, the compensation signal may not be accurately acquired from the second switching element.

In the force detection device of the present invention, the first switching element and the second switching element are semiconductor switching elements that generate a leakage current, and the first switching element and the second switching element are the first switching element and the second switching element, respectively. Mounted on the same semiconductor substrate so that the leakage current of the first switching element and the leakage current of the second switching element are interlocked, and the compensation signal output circuit is connected to the second switching element. It is preferable to detect a leakage current and output the detected leakage current as the compensation signal.
Thereby, the compensation signal output circuit can indirectly acquire the leakage current of the first switching element by detecting the leakage current of the second switching element.

In the force detection device of the present invention, the external force detection circuit corrects by providing a gain to at least one of the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit. Preferably, the external force detection circuit detects the external force by taking a difference between the voltage corrected by the gain correction unit and the compensation signal.
Thereby, the sensitivity difference between the voltage and the compensation signal due to the difference between the capacitance C1 of the first capacitor and the capacitance C2 of the second capacitor can be corrected.

In the force detection device of the present invention, the element is configured by stacking a plurality of ground electrode layers grounded to the ground and at least three sensors, and the force detection directions of the sensors are orthogonal to each other. Preferably it is.
Thereby, the element can output electric charges according to each of external forces along three axes orthogonal to each other.

In the force detection device of the present invention, it is preferable that at least one of the sensors includes an X-cut crystal, and at least two of the sensors include a Y-cut crystal.
Thereby, the element can output charges corresponding to the shearing force and the compressive force.
In the force detection device of the present invention, each of the sensors is provided with a first piezoelectric layer having a first crystal axis, a second crystal axis, which is provided to face the first piezoelectric layer. A second piezoelectric layer; and an output electrode layer provided between the first piezoelectric layer and the second piezoelectric layer, wherein the first piezoelectric layer includes the first piezoelectric layer. It is preferable that the crystal axis is directed in a direction opposite to the direction of the second crystal axis of the second piezoelectric layer.
Thereby, the positive charge or negative charge collected near the 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 further includes a first substrate and a second substrate facing the first substrate, and the element is between the first substrate and the second substrate. It is preferable to be provided.
Thereby, an external force applied to the first substrate or the second substrate can be detected.

The force detection device of the present invention has a plurality of the elements,
The respective elements are preferably arranged at equiangular intervals along the circumferential direction of the first substrate or the second substrate.
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 includes an element that outputs an electric charge according to the external force, a first switching element, and a first capacitor, and converts the electric charge into a voltage and outputs the voltage. A compensation signal output circuit that outputs a compensation signal, the voltage output from the conversion output circuit, and the compensation signal output circuit. An external force detection circuit for detecting the external force based on the output compensation signal;
The capacitance of the second capacitor is smaller than the capacitance of the first capacitor.
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.

The electronic component transport device of the present invention includes a motor, a gripping unit that is driven by the motor and grips the electronic component, and a force detection device that detects an external force applied to the gripping unit,
The force detection device includes an element that outputs an electric charge according to the external force, a first switching element, and a first capacitor, and converts the electric charge into a voltage and outputs the voltage. A compensation signal output circuit that outputs a compensation signal, the voltage output from the conversion output circuit, and the compensation signal output circuit. An external force detection circuit for detecting the external force based on the output compensation signal;
The capacitance of the first capacitor is larger than the capacitance of the second capacitor.

  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.

An electronic component inspection apparatus according to the present invention includes a motor, a gripper that is driven by the motor and grips the electronic component, an inspection unit that inspects the electronic component, and a force detection device that detects an external force applied to the gripper. And
The force detection device includes an element that outputs an electric charge according to the external force, a first switching element, and a first capacitor, and converts the electric charge into a voltage and outputs the voltage. A compensation signal output circuit that outputs a compensation signal, the voltage output from the conversion output circuit, and the compensation signal output circuit. An external force detection circuit for detecting the external force based on the output compensation signal;
The capacitance of the first capacitor is larger than the capacitance of the second capacitor.

  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.

It is a circuit diagram showing roughly a 1st embodiment of a force detection device of the present invention. It is sectional drawing which shows schematically the electric charge output element of the force detection apparatus shown in FIG. It is sectional drawing and the top view which show the example of mounting of the capacitor | condenser of the force detector shown in FIG. It is a circuit diagram which shows schematically 2nd Embodiment of the force detection apparatus of this invention. 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 perspective view which shows schematically 3rd Embodiment of the force detection apparatus of this invention. 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.

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. 1 is a circuit diagram schematically showing a first embodiment of the force detection device of the present invention. FIG. 2 is a cross-sectional view schematically showing a charge output element of the force detection device shown in FIG. FIG. 3 is a cross-sectional view and a plan view showing a mounting example of the capacitor of the force detection device shown in FIG.

  The force detection device 1a shown in FIG. 1 has a function of detecting an external force applied along an arbitrary axis (x axis, y axis, or z axis). The force detection device 1a includes a charge output element (element) 10a that outputs a charge Q in accordance with an external force applied (received) along an arbitrary axis, and a charge Q output from the charge output element 10a as a voltage. From the conversion output circuit 20 that converts to V and outputs the voltage V, the compensation signal output circuit 30 that outputs the compensation signal Voff, the voltage V that is output from the conversion output circuit 20, and the compensation signal output circuit 30 An external force detection circuit 40a that detects the applied external force based on the output compensation signal Voff is provided.

<Charge output element (element)>
The charge output element 10a shown in FIG. 2 has a function of outputting a charge Q according to an external force (shearing force) applied (received) along the β axis in FIG. The charge output element 10 a includes two ground electrode layers 11 and a sensor 12 provided between the two ground electrode layers 11. In FIG. 2, the lamination direction of the ground electrode layer 11 and the sensor 12 is the 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, respectively.
In the illustrated configuration, the ground electrode layer 11 and the sensor 12 all have the same width (length in the left-right direction in the figure), but the present invention is not limited to this. For example, the width of the ground electrode layer 11 may be wider than the width of the sensor 12 or vice versa.

  The ground electrode layer 11 is an electrode grounded to the ground (reference potential point). Although the material which comprises the ground electrode layer 11 is not specifically limited, For example, gold | metal | money, titanium, aluminum, copper, iron, or an alloy containing these is preferable. Among these, it is particularly preferable to use stainless steel which is an iron alloy. The ground electrode layer 11 made of stainless steel has excellent durability and corrosion resistance.

The sensor 12 has a function of outputting a charge Q according to an external force (shearing force) applied (received) along the β axis. This sensor 12 is configured to output a positive charge according to an external force applied 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.
The sensor 12 is provided so as to face the first piezoelectric layer 121 having the first crystal axis CA1 and the first piezoelectric layer 121, and the second piezoelectric layer 123 having the second crystal axis CA2. And an output electrode layer 122 that outputs a charge Q and is provided between the first piezoelectric layer 121 and the second piezoelectric layer 123.

  The first piezoelectric layer 121 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 121, electric charges are induced in the first piezoelectric layer 121 due to the piezoelectric effect. As a result, positive charges gather near the surface of the first piezoelectric layer 121 on the output electrode layer 122 side, and negative charges gather near the surface of the first piezoelectric layer 121 on the ground electrode layer 11 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 121, negative charges are generated near the surface of the first piezoelectric layer 121 on the output electrode layer 122 side. As a result, positive charges are collected in the vicinity of the surface of the first piezoelectric layer 121 on the ground electrode layer 11 side.

  The second piezoelectric layer 123 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 123, electric charges are induced in the second piezoelectric layer 123 due to the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the second piezoelectric layer 123 on the output electrode layer 122 side, and negative charges are collected in the vicinity of the surface of the second piezoelectric layer 123 on the ground electrode layer 11 side. Similarly, when an external force along the negative direction of the β axis is applied to the surface of the second piezoelectric layer 123, negative charges are generated near the surface of the second piezoelectric layer 123 on the output electrode layer 122 side. As a result, positive charges are collected near the surface of the second piezoelectric layer 123 on the ground electrode layer 11 side.

  Thus, the first crystal axis CA1 of the first piezoelectric layer 121 is oriented in the direction opposite to the direction of the second crystal axis CA2 of the second piezoelectric layer 123. As a result, as compared with the case where the sensor 12 is configured by only one of the first piezoelectric layer 121 and the second piezoelectric layer 123 and the output electrode layer 122, the positive charge collected near the output electrode layer 122. Or the negative charge can be increased. As a result, the charge Q output from the output electrode layer 122 can be increased.

The constituent materials of the first piezoelectric layer 121 and the second piezoelectric layer 123 include 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. Further, like the first piezoelectric layer 121 and the second piezoelectric layer 123, a piezoelectric layer that generates an electric charge with respect to an external force (shearing force) along the surface direction of the layer is configured by a Y-cut crystal. be able to.

  The output electrode layer 122 has a function of outputting positive charges or negative charges generated in the first piezoelectric layer 121 and the second piezoelectric layer 123 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 121 or the surface of the second piezoelectric layer 123, a positive charge is present in the vicinity of the output electrode layer 122. Gather. As a result, a positive charge Q is output from the output electrode layer 122. 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 121 or the surface of the second piezoelectric layer 123, negative charges are collected in the vicinity of the output electrode layer 122. As a result, a negative charge Q is output from the output electrode layer 122.

The width of the output electrode layer 122 is preferably equal to or greater than the width of the first piezoelectric layer 121 and the second piezoelectric layer 123. When the width of the output electrode layer 122 is narrower than that of the first piezoelectric layer 121 or the second piezoelectric layer 123, a part of the first piezoelectric layer 121 or the second piezoelectric layer 123 is the output electrode layer. No contact with 122. Therefore, some of the charges generated in the first piezoelectric layer 121 or the second piezoelectric layer 123 may not be output from the output electrode layer 122. As a result, the charge Q output from the output electrode layer 122 decreases.
Thus, the charge output element 10a can output the charge Q according to the external force parallel to the β axis in FIG. 2 by having the ground electrode layer 11 and the sensor 12 described above.

  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 10a, the present invention is not limited to this. By using the first piezoelectric layer 121 having a different orientation direction of the first crystal axis CA1 and the second piezoelectric layer 123 having a different orientation direction of the second crystal axis CA2, an external force (shear) parallel to the α axis is used. Force) or an external force (compression / tensile force) parallel to the γ-axis, the charge output element 10a that outputs the charge Q can be configured. Such a case is also within the scope of the present invention.

<Conversion output circuit>
The conversion output circuit 20 has a function of converting the charge Q output from the charge output element 10a into a voltage V and outputting the voltage V. The conversion output circuit 20 includes an operational amplifier 21, a capacitor 22, and a switching element 23. The first input terminal (minus input) of the operational amplifier 21 is connected to the output electrode layer 122 of the charge output element 10a, and the second input terminal (plus input) of the operational amplifier 21 is grounded to the ground (reference potential point). ing. The output terminal of the operational amplifier 21 is connected to the external force detection circuit 40a. The capacitor 22 is connected between the first input terminal and the output terminal of the operational amplifier 21. The switching element 23 is connected between the first input terminal and the output terminal of the operational amplifier 21 and is connected in parallel with the capacitor 22. The switching element 23 is connected to a drive circuit (not shown), and the switching element 23 performs a switching operation in accordance with an on / off signal from the drive circuit.

  When the switching element 23 is off, the charge Q output from the charge output element 10a is stored in the capacitor 22 having the capacitance C1, and is output as the voltage V to the external force detection circuit 40a. Next, when the switch element 23 is turned on, both terminals of the capacitor 22 are short-circuited. As a result, the electric charge Q stored in the capacitor 22 is discharged to 0 coulomb, and the voltage V output to the external force detection circuit 40a is 0 volt. When the switching element 23 is turned on, the conversion output circuit 20 is reset.

  The switching element 23 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 23 will be described as a representative example.

  The switching element 23 has a drain electrode, a source electrode, and a gate electrode. One of the drain electrode and the source electrode of the switching element 23 is connected to the first input terminal of the operational amplifier 21, and the other of the drain electrode and the source electrode is connected to the output terminal of the operational amplifier 21. The gate electrode of the switching element 23 is connected to a drive circuit (not shown).

The voltage V output from the ideal conversion output circuit 20 is proportional to the accumulation amount of the charge Q output from the charge output element 10a. However, in the actual conversion output circuit 20, a leak current that flows from the switching element 23 into the capacitor 22 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 is a problem that the detection accuracy and the detection resolution of the force detection device 1a are lowered. 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 of the present invention uses the compensation signal Voff output from the compensation signal output circuit 30 described below to reduce the influence of the leakage current caused by the semiconductor structure and the leakage current caused by the use environment (compensation). )can do.

<Compensation signal output circuit>
The compensation signal output circuit 30 has a function of outputting a compensation signal Voff for compensating the voltage V output from the conversion output circuit 20. The compensation signal output circuit 30 may be provided independently of the conversion output circuit 20 as illustrated. Here, “provided independently” means components of the compensation signal output circuit 30 (an operational amplifier 31, a capacitor 32, and a switching element 33 described later) and components of the conversion output circuit 20 (that is, the operational amplifier 21, It means that the capacitor 22 and the switching element 23) are different elements (components). That is, the compensation signal output circuit 30 is provided separately from the conversion output circuit 20 and does not share the components.

  The compensation signal output circuit 30 includes an operational amplifier 31, a capacitor 32, and a switching element 33. The first input terminal (minus input) of the operational amplifier 31 is connected to the capacitor 32 and the switching element 33, and the input terminal (plus input) of the operational amplifier 31 is grounded to the ground (reference potential point). The output terminal of the operational amplifier 31 is connected to the external force detection circuit 40a. The capacitor 32 is connected between the input terminal and the output terminal of the operational amplifier 31. The switching element 33 is connected between the first input terminal and the output terminal of the operational amplifier 31 and is connected in parallel with the capacitor 32. The switching element 33 is connected to a drive circuit (not shown), and the switching element 33 performs a switching operation in accordance with an on / off signal from the drive circuit.

  The switching element 33 is a semiconductor switching element (MOSFET) similar to the switching element 23 of the conversion output circuit 20. The switching element 33 has a drain electrode, a source electrode, and a gate electrode. One of the drain electrode and the source electrode of the switching element 33 is connected to the first input terminal of the operational amplifier 31, and the other of the drain electrode and the source electrode is connected to the output terminal of the operational amplifier 31. The gate electrode of the switching element 33 is connected to a drive circuit (not shown).

  The drive circuit connected to the switching element 33 may be the same drive circuit as the drive circuit connected to the switching element 23 of the conversion output circuit 20, or may be a different drive circuit. When the drive circuit connected to the switching element 33 and the drive circuit connected to the switching element 23 are different drive circuits, the drive circuit connected to the switching element 33 is different from the drive circuit connected to the switching element 23. Output synchronized on / off signal. Thereby, the switching operation of the switching element 33 and the switching operation of the switching element 23 are synchronized. That is, the ON / OFF timings of the switching element 33 and the switching element 23 are the same.

  The switching element 33 is a semiconductor switching element similar to the switching element 23 of the conversion output circuit 20. Therefore, the leakage current resulting from the semiconductor structure of the switching element 33 is substantially equal to the leakage current resulting from the semiconductor structure of the switching element 23. Here, “substantially equal” means that the difference between the leakage current due to the semiconductor structure of the switching element 33 and the leakage current due to the semiconductor structure of the switching element 23 is This means that the leakage current is sufficiently small to be negligible compared to the resulting leakage current.

  Further, the switching element 33 is mounted in a use environment equivalent to the switching element 23 of the conversion output circuit 20. “Usage environment” here refers to temperature and humidity. Thereby, the leakage current resulting from the usage environment of the switching element 33 and the leakage current resulting from the usage environment of the switching element 23 can be made substantially equal. As used herein, “substantially equal” means that the difference between the leakage current resulting from the usage environment of the switching element 33 and the leakage current resulting from the usage environment of the switching element 23 depends on the usage environment of the switching elements 23 and 33. This means that the leakage current is sufficiently small to be negligible compared to the resulting leakage current.

As a result, the leakage current of the switching element 33 is linked with the leakage current of the switching element 23. That is, when the leakage current of the switching element 23 increases, the leakage current of the switching element 33 increases similarly, and when the leakage current of the switching element 23 decreases, the leakage current of the switching element 33 decreases similarly. Thereby, the compensation signal output circuit 30 can indirectly acquire the leakage current of the switching element 23 by detecting the leakage current of the switching element 33.
The above-mentioned “under equivalent use environment” means, for example, when the switching element 33 is mounted in the vicinity of the switching element 23, when the switching element 23 and the switching element 33 are mounted in the same housing, 23 and the switching element 33 are mounted on the same semiconductor substrate.

  Among these, it is preferable that the switching element 23 and the switching element 33 are mounted on the same semiconductor substrate. By mounting the switching element 23 and the switching element 33 on the same semiconductor substrate, the temperature and humidity around the switching element 23 and the temperature and humidity around the switching element 33 can be easily made substantially equal. Here, “substantially equal” means that the difference between the temperature and humidity around the switching element 33 and the temperature and humidity of the switching element 23 is sufficiently small to be negligible.

Further, when the switching element 23 and the switching element 33 are mounted on the same semiconductor substrate, the switching element 23 and the switching element 33 can be formed by the same process, which is advantageous for shortening the work process. In addition, since the switching element 23 and the switching element 33 can be formed by the same process, variations in characteristics of the switching element 23 and the switching element 33 can be suppressed. Therefore, the leakage current caused by the semiconductor structure of the switching element 23 and the leakage current caused by the semiconductor structure of the switching element 33 can be equalized with higher accuracy.
When the switching element 33 is off, the leakage current generated in the switching element 33 flows into the capacitor 32 having the capacitance C2 and is stored in the charge, so that the compensation signal Voff is output to the external force detection circuit 40a. The Next, when the switching element 33 is turned on, both terminals of the capacitor 32 are short-circuited. As a result, the charge Q stored in the capacitor 32 is discharged to 0 coulomb, and the compensation signal Voff output to the external force detection circuit 40a is 0 volt.

  In a circuit having a voltage conversion function such as the conversion output circuit 20 and the compensation signal output circuit 30, when the capacitance of the capacitor is reduced, the voltage conversion sensitivity is improved, but the saturation charge amount is reduced. Usually, the leakage current of a semiconductor switching element such as the switching elements 23 and 33 is smaller than the charge Q input from the charge output element 10a. Therefore, the capacitance C2 of the capacitor 32 is preferably smaller than the capacitance C1 of the capacitor 22. As a result, the leakage current generated in the switching element 33 can be more accurately converted into a voltage.

  The capacitance ratio C2 / C1 between the capacitance C1 of the capacitor 22 and the capacitance C2 of the capacitor 32 is preferably 0.1 to 0.8, and is preferably 0.3 to 0.6. Is more preferable. When the capacitance ratio C2 / C1 falls below the lower limit value, the capacitor 32 may be saturated due to a leak current generated in the switching element 33. On the other hand, if the capacitance ratio C2 / C1 exceeds the upper limit value, sufficient sensitivity to the leakage current generated in the switching element 33 may not be obtained.

FIG. 3 shows an example of a circuit in which two capacitors 22 and capacitors 32 having different capacitances are mounted on the same semiconductor substrate. FIG. 3A is a plan view of a circuit having the capacitor 22 and the capacitor 32. In FIG. 3A, for the sake of explanation, some components are in a transparent state. FIG.3 (b) is the sectional view on the AA line in Fig.3 (a).
3 includes a semiconductor substrate 50, interlayer insulating layers 60 and 70 provided on the semiconductor substrate 50, capacitors 22 and 32 provided on the interlayer insulating layer 60, power distribution layers 80a and 80b, And a through hole 71 provided in the insulating layer 70.

The capacitor 22 is electrically connected to the operational amplifier 21 and the switching element 23 (not shown in FIG. 3) via the power distribution layer 80a and the through hole 71. Similarly, the capacitor 32 is electrically connected to the operational amplifier 31 and the switching element 33 (not shown in FIG. 3) via the power distribution layer 80b and the through hole 71.
The capacitor 22 having the capacitance C1 is provided between the capacitor lower electrode layer 221, the two capacitor upper electrode layers 223 facing the capacitor lower electrode layer 221, and the capacitor lower electrode layer 221 and the capacitor upper electrode layer 223. Capacitor insulating layer 222 formed.

The capacitor 32 having the capacitance C2 is provided between the capacitor lower electrode layer 321, the capacitor upper electrode layer 323 facing the capacitor lower electrode layer 321, and the capacitor lower electrode layer 321 and the capacitor upper electrode layer 323. And a capacitor insulating layer 322.
Capacitance of a capacitor having a structure such as the capacitor 22 and the capacitor 32 is proportional to the area of the capacitor upper electrode layer. In the illustrated configuration, the area of the capacitor upper electrode layer 323 of the capacitor 32 is smaller than the area of the capacitor upper electrode layer 223 of the capacitor 22. By having such a configuration, two capacitors 22 and 23 having different electrostatic capacities can be mounted on the same semiconductor substrate 50.

  Although the mounting example of the two capacitors 22 and 23 having different capacitances has been described using FIG. 3, the present invention is not limited to this. For example, the compensation signal output circuit 30 may have a plurality of capacitors connected in series. As a result, the capacitance of the capacitor of the compensation signal output circuit 30 can be reduced, and the capacitance of the capacitor of the compensation signal output circuit 30 can be made smaller than the capacitance of the capacitor of the conversion output circuit 20. Can do. The conversion output circuit 20 may include a plurality of capacitors connected in parallel. Thereby, the capacitance of the capacitor of the conversion output circuit 20 can be increased, and the capacitance of the capacitor of the compensation signal output circuit 30 can be made smaller than the capacitance of the capacitor of the conversion output circuit 20. . Such a case is also within the scope of the present invention.

<External force detection circuit>
The external force detection circuit 40 a has a function of detecting the applied external force based on the voltage V output from the conversion output circuit 20 and the compensation signal Voff output from the compensation signal output circuit 30. The external force detection circuit 40a includes an amplifier 41a connected to the conversion output circuit 20, an amplifier 42a connected to the compensation signal output circuit 30, and a differential amplifier 43a connected to the amplifiers 41a and 42a.

  The input terminal of the amplifier 41a is connected to the output terminal of the operational amplifier 21 of the conversion output circuit 20, and the output terminal of the amplifier 41a is connected to the first input terminal (minus input) of the differential amplifier 43a. The input terminal of the amplifier 42a is connected to the output terminal of the operational amplifier 31 of the compensation signal output circuit 30, and the output terminal of the amplifier 42a is connected to the second input terminal (plus input) of the differential amplifier 43a. Yes.

The amplifier 41a has a function of correcting the voltage V output from the conversion output circuit 20 by applying a gain G = a. The amplifier 42a has a function of correcting the compensation signal Voff output from the compensation signal output circuit 30 by applying a gain G = b.
The gain coefficient a of the amplifier 41a and the gain coefficient b of the amplifier 42a preferably satisfy a relational expression of a = C1 / C2 × b. Here, C1 is the capacitance of the capacitor 22 of the conversion output circuit 20, and C2 is the capacitance of the capacitor 32 of the compensation signal output circuit 30. Thereby, the sensitivity difference between the voltage V and the compensation signal Voff due to the difference between the capacitance C1 of the capacitor 22 and the capacitance C2 of the capacitor 32 can be corrected. As a result, the value of the corrected output drift D (ie, a × D) and the corrected compensation signal Voff (ie, b × D) are substantially equal. Here, “substantially equal” means that the difference between the corrected output drift D (ie, a × D) and the corrected compensation signal Voff (ie, b × D) is sufficiently negligible. Means small. Note that a = 1 means that the voltage V is not corrected. Similarly, b = 1 means that the compensation signal Voff is not corrected.

The differential amplifier 43a has a function of taking the difference between the voltage V corrected by the amplifier 41a and the compensation signal Voff corrected by the amplifier 42a and outputting the signal F. As described above, the value of the output drift included in the corrected voltage V and caused by the leakage current is substantially equal to the value of the corrected compensation signal Voff. Therefore, the signal F output from the output terminal of the differential amplifier 43a is as follows.
F = a × V−b × Voff
= A * (Vt + D) -b * Voff
= A × Vt + a × D−b × Voff
≒ a x Vt

  Thus, by taking the difference between the corrected voltage V and the corrected compensation signal Voff, the output drift D caused by the leakage current can be reduced (removed) from the corrected voltage V. By having such a configuration, the external force detection circuit 40a can output a signal F proportional to the amount of charge Q output from the charge output element 10a. Since the signal F corresponds to the external force applied to the charge output element 10a, the force detection device 1a can detect the external force applied to the charge output element 10a.

  As described above, the force detection device 1a of the present invention includes the compensation signal output circuit 30 and the external force detection circuit 40a, thereby reducing the output drift D caused by the leakage current of the switching element 23 of the conversion output circuit 20. can do. 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.

Second Embodiment
Next, a second embodiment of the present invention will be described based on FIG. 4 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. 4 is a circuit diagram schematically showing a second embodiment of the force detection device of the present invention. FIG. 5 is a cross-sectional view schematically showing the charge output element of the force detection device shown in FIG.

  The force detection device 1b shown in FIG. 4 has a function of detecting an external force applied along three axes (α (X) axis, β (Y) axis, γ (Z) axis) orthogonal to each other. The force detection device 1b includes a charge output element (element) 10b that outputs three charges Qx, Qy, and Qz in accordance with external forces applied (received) along three axes orthogonal to each other, and a charge output element A conversion output circuit 20a that converts the charge Qx output from the charge output element 10b into a voltage Vx; a conversion output circuit 20b that converts the charge Qz output from the charge output element 10b into a voltage Vz; and a charge output from the charge output element 10b. A conversion output circuit 20c that converts Qy into a voltage Vy, a compensation signal output circuit 30 that outputs a compensation signal Voff, and an external force detection circuit 40b that detects the applied external force are provided.

<Charge output element (element)>
The charge output element 10b has a function of outputting three charges Qx, Qy, and Qz according to external forces applied (received) along three axes orthogonal to each other. As shown in FIG. 5, the charge output element 10b outputs the charge Qy according to the four ground electrode layers 11 grounded to the ground (reference potential point) and the external force (shearing force) parallel to the β axis. 1 sensor 12, a second sensor 13 that outputs a charge Qz according to an external force (compression / tensile force) parallel to the γ-axis, and a charge Qx according to an external force (shearing force) parallel to the α-axis The ground electrode layer 11 and the sensors 12, 13, and 14 are alternately stacked. In FIG. 5, the stacking direction of the ground electrode layer 11 and the sensors 12, 13, 14 is defined as the γ-axis direction, and the directions orthogonal to the γ-axis direction and orthogonal to each other are defined as an α-axis direction and a β-axis direction, respectively.

In the illustrated configuration, the first sensor 12, the second sensor 13, and the third sensor 14 are stacked in this order from the lower side in FIG. 5, but the present invention is not limited to this. The stacking order of the sensors 12, 13, and 14 is arbitrary.
The first sensor 12 has a function of outputting a charge Qy according to an external force (shearing force) parallel to the β axis. The first sensor 12 has the same structure and function as the sensor 12 of the first embodiment described above.

The second sensor 13 has a function of outputting a charge Qz according to an external force (compression / tensile force) applied (received) along the γ axis. The second sensor 13 is configured to output a positive charge according to a compressive force parallel to the γ axis and to output a negative charge according to a tensile force parallel to the γ axis.
The second sensor 13 is provided with a third piezoelectric layer 131 having a third crystal axis CA3 and a third piezoelectric layer 131 facing the third piezoelectric layer 131 and having a fourth crystal axis CA4. There is an output electrode layer 132 that is provided between the body layer 133, the third piezoelectric layer 131, and the fourth piezoelectric layer 133 and outputs a charge Qz.

  The third piezoelectric layer 131 is composed of a piezoelectric body having a third crystal axis CA3 oriented in the positive direction of the γ axis. When a compressive force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 131, electric charges are induced in the third piezoelectric layer 131 due to the piezoelectric effect. As a result, positive charges gather near the surface of the third piezoelectric layer 131 on the output electrode layer 132 side, and negative charges gather near the surface of the third piezoelectric layer 131 on the ground electrode layer 11 side. Similarly, when a tensile force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 131, negative charges gather near the surface of the third piezoelectric layer 131 on the output electrode layer 132 side, Positive charges collect near the surface of the third piezoelectric layer 131 on the ground electrode layer 11 side.

  The fourth piezoelectric layer 133 is composed of a piezoelectric body having a fourth crystal axis CA4 oriented in the negative direction of the γ axis. When a compressive force parallel to the γ-axis is applied to the surface of the fourth piezoelectric layer 133, charges are induced in the fourth piezoelectric layer 133 due to the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the fourth piezoelectric layer 133 on the output electrode layer 132 side, and negative charges are collected in the vicinity of the surface of the fourth piezoelectric layer 133 on the ground electrode layer 11 side. Similarly, when a tensile force parallel to the γ-axis is applied to the surface of the fourth piezoelectric layer 133, negative charges gather near the surface of the fourth piezoelectric layer 133 on the output electrode layer 132 side, Positive charges are collected near the surface of the fourth piezoelectric layer 133 on the ground electrode layer 11 side.

As the constituent material of the third piezoelectric layer 131 and the fourth piezoelectric layer 133, the same constituent material as that of the first piezoelectric layer 121 and the second piezoelectric layer 123 can be used. In addition, like the third piezoelectric layer 131 and the fourth piezoelectric layer 133, the piezoelectric layer that generates an electric charge with respect to an external force (compression / tensile force) perpendicular to the surface direction of the layer is made of X-cut quartz. Can be configured.
The output electrode layer 132 has a function of outputting positive charges or negative charges generated in the third piezoelectric layer 131 and the fourth piezoelectric layer 133 as charges Qz. As described above, when a compressive force parallel to the γ axis is applied to the surface of the third piezoelectric layer 131 or the surface of the fourth piezoelectric layer 133, positive charges are collected in the vicinity of the output electrode layer 132. . As a result, a positive charge Qz is output from the output electrode layer 132. On the other hand, when a tensile force parallel to the γ axis is applied to the surface of the third piezoelectric layer 131 or the surface of the fourth piezoelectric layer 133, negative charges are collected in the vicinity of the output electrode layer 132. As a result, a negative charge Qz is output from the output electrode layer 132.

The third sensor 14 has a function of outputting a charge Qx according to an external force (shearing force) applied (received) along the α axis. The third sensor 14 is configured to output a positive charge according to an external force applied 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.
The third sensor 14 is provided to face the fifth piezoelectric layer 141 having the fifth crystal axis CA5 and the fifth piezoelectric layer 141, and the sixth piezoelectric layer having the sixth crystal axis CA6. It has an output electrode layer 142 that is provided between the body layer 143, the fifth piezoelectric layer 141, and the sixth piezoelectric layer 143, and outputs a charge Qx.

  The fifth piezoelectric layer 141 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 141, electric charges are induced in the fifth piezoelectric layer 141 by the piezoelectric effect. As a result, positive charges gather near the surface of the fifth piezoelectric layer 141 on the output electrode layer 142 side, and negative charges gather near the surface of the fifth piezoelectric layer 141 on the ground electrode layer 11 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 141, negative charges are generated near the surface of the fifth piezoelectric layer 141 on the output electrode layer 142 side. As a result, positive charges are collected in the vicinity of the surface of the fifth piezoelectric layer 141 on the ground electrode layer 11 side.

  The sixth piezoelectric layer 143 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 143, electric charges are induced in the sixth piezoelectric layer 143 by the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the sixth piezoelectric layer 143 on the output electrode layer 142 side, and negative charges are collected in the vicinity of the surface of the sixth piezoelectric layer 143 on the ground electrode layer 11 side. Similarly, when an external force along the negative direction of the α axis is applied to the surface of the sixth piezoelectric layer 143, negative charges are generated near the surface of the sixth piezoelectric layer 143 on the output electrode layer 142 side. The positive charges are collected near the surface of the sixth piezoelectric layer 143 on the side of the ground electrode layer 11.

  As the constituent materials of the fifth piezoelectric layer 141 and the sixth piezoelectric layer 143, the same constituent materials as those of the first piezoelectric layer 121 and the second piezoelectric layer 123 can be used. Further, like the fifth piezoelectric layer 141 and the sixth piezoelectric layer 143, 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 121 and the second piezoelectric layer 123, it can be composed of Y-cut quartz.

  The output electrode layer 142 has a function of outputting positive charges or negative charges generated in the fifth piezoelectric layer 141 and the sixth piezoelectric layer 143 as the charge Qx. 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 141 or the surface of the sixth piezoelectric layer 143, a positive charge is generated in the vicinity of the output electrode layer 142. Gather. As a result, a positive charge Qx is output from the output electrode layer 142. 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 141 or the surface of the sixth piezoelectric layer 143, negative charges are collected in the vicinity of the output electrode layer 142. As a result, a negative charge Qx is output from the output electrode layer 142.

  Thus, the 1st sensor 12, the 2nd sensor 13, and the 3rd sensor 14 are laminated so that the force detection directions of each sensor may be orthogonal to each other. Thereby, each sensor can induce an electric charge according to force components orthogonal to each other. Therefore, the charge output element 10b outputs three charges Qx, Qy, and Qz according to the external forces along the three axes (α (X) axis, β (Y) axis, γ (Z) axis). Can do.

  Moreover, the charge generation amount per unit force of the first sensor 12 and the third sensor 14 constituted by the Y-cut quartz is, for example, 8 pC / N. The charge generation amount per unit force of the second sensor 13 constituted by the X-cut quartz is, for example, 4 pC / N. Therefore, the sensitivity of the charge output element 10b to an external force (compression / tensile force) parallel to the γ axis is usually lower than the sensitivity of the charge output element 10b to an external force (shear force) parallel to the α axis or β axis. Therefore, the charge Qz output from the second sensor 13 is usually smaller than the charge Qy output from the first sensor 12 and the charge Qx output from the third sensor 14.

<Conversion output circuit>
The conversion output circuits 20a and 20c have the same configuration as the conversion output circuit 20 of the first embodiment. The conversion output circuit 20b has the same configuration as the conversion output circuit 20 of the first embodiment except for the electrostatic capacitance C3 of the capacitor 22. The conversion output circuit 20a has a function of converting the charge Qx output from the charge output element 10b into a voltage Vx. The conversion output circuit 20b has a function of converting the charge Qz output from the charge output element 10b into a voltage Vz. The conversion output circuit 20c has a function of converting the charge Qy output from the charge output element 10b into a voltage Vy.

  The same drive circuit may be connected to the switching element 23 of each conversion output circuit 20a, 20b, 20c, and a different drive circuit may be connected to each. All the switching elements 23 are supplied with ON / OFF signals that are all synchronized from the drive circuit. Thereby, operation | movement of the switching element 23 of each conversion output circuit 20a, 20b, 20c synchronizes. That is, the on / off timings of the switching elements 23 of the conversion output circuits 20a, 20b, and 20c are the same.

  As described above, the charge Qz output from the second sensor 13 is usually smaller than the charge Qy output from the first sensor 12 and the charge Qx output from the third sensor 14. Therefore, the capacitance C3 of the capacitor 22 of the conversion output circuit 20b is preferably smaller than the capacitance C1 of the capacitor 22 of the conversion output circuits 20a and 20c. Thereby, the electric charge Qz can be accurately converted into a voltage.

  The capacitance ratio C3 / C1 between the capacitance C1 and the capacitance C3 is preferably 0.3 to 0.8, and more preferably 0.45 to 0.6. When the capacitance ratio C3 / C1 falls below the lower limit value, the capacitor 22 may be saturated by the charge Qz. On the other hand, if the capacitance ratio C3 / C1 exceeds the upper limit, sufficient sensitivity to the charge Qz may not be obtained.

Moreover, since the switching element 23 of each conversion output circuit 20a, 20b, 20c is an equivalent semiconductor switching element, and is mounted in the equivalent use environment, the leakage current of each switching element 23 is substantially equal. . Therefore, the output drift D of each switching element 23 is also substantially equal.
The above-mentioned “under the same usage environment” means that, for example, when each switching element 23 is mounted in the vicinity of each other, when each switching element 23 is mounted in the same casing, each switching element 23 is the same The case where it mounts on the semiconductor substrate of this is mentioned.

  Among these, it is preferable that each switching element 23 is mounted on the same semiconductor substrate. By mounting each switching element 23 on the same semiconductor substrate, the temperature and humidity around each switching element 23 can be made substantially equal. Moreover, when each switching element 23 is mounted on the same semiconductor substrate, each switching element 23 can be formed by the same process, which is advantageous for shortening the work process. Moreover, since each switching element 23 can be formed by the same process, the characteristic variation of each switching element 23 can be suppressed. Therefore, the leak currents resulting from the semiconductor structure of each switching element 23 can be equalized with higher accuracy.

<Compensation signal output circuit>
The compensation signal output circuit 30 has the same configuration as the compensation signal output circuit 30 of the first embodiment. The compensation signal output circuit 30 receives a compensation signal Voff for compensating the voltage Vx output from the conversion output circuit 20a, the voltage Vz output from the conversion output circuit 20b, and the voltage Vy output from the conversion output circuit 20c. Has a function to output. The compensation signal output circuit 30 may be provided independently of the conversion output circuits 20a, 20b, and 20c as shown in the figure.

  Further, the switching element 33 of the compensation signal output circuit 30 is mounted under the same use environment as the switching element 23 of each of the conversion output circuits 20a, 20b, and 20c. Thereby, the leakage current of the switching element 33 is interlocked with the leakage current of each switching element 23. Therefore, the compensation signal output circuit 30 can indirectly acquire the leakage current of each switching element 23 by detecting the leakage current of the switching element 33. The compensation signal output circuit 30 outputs the acquired leakage current of the switching element 33 as the compensation signal Voff.

  Thus, the compensation signal output circuit 30 can indirectly acquire the leakage current of the switching element 23 of each of the conversion output circuits 20a, 20b, and 20c by detecting the leakage current of the switching element 33. Therefore, the force detection device 1b of the present invention does not need to provide three leak current detection circuits for each of the conversion output circuits 20a, 20b, and 20c. Therefore, the number of circuits required for the force detection device 1b can be reduced, and the force detection device 1b can be reduced in size and weight.

  The capacitance C2 of the capacitor 32 of the compensation signal output circuit 30 is preferably smaller than the capacitance C3 of the capacitor 22 of the second sensor 13. That is, the magnitude relationship between the capacitances C1 and C3 of the capacitor 22 and the capacitance C2 of the capacitor 32 is preferably C2 <C3 <C1. Thereby, the charges Qx, Qy, Qz and the leakage current of the switching element 33 can be accurately converted into voltages.

<External force detection circuit>
The external force detection circuit 40b outputs the voltage Vx output from the conversion output circuit 20a, the voltage Vz output from the conversion output circuit 20b, the voltage Vy output from the conversion output circuit 20c, and the compensation signal output circuit 30. And a function of detecting the applied external force based on the compensation signal Voff. The external force detection circuit 40b includes an AD converter 41b connected to the conversion output circuits 20a, 20b, and 20c and the compensation signal output circuit 30, and an arithmetic circuit 42b connected to the AD converter 41b.

The AD converter 41b has a function of converting the voltages Vx, Vy, Vz and the compensation signal Voff from an analog signal to a digital signal. The voltages Vx, Vy, Vz and the compensation signal Voff digitally converted by the AD converter 41b are input to the arithmetic circuit 42b.
The arithmetic circuit 42b includes a gain correction unit (not shown) that performs a correction by giving a gain to the digitally converted voltages Vx, Vy, Vz and the compensation signal Voff, and the voltages Vx, Vy, Based on Vz and the compensation signal Voff, an arithmetic unit (not shown) that calculates and outputs signals Fx, Fy, and Fz.

  The gain correction unit gives a gain G = a to the voltages Vx and Vy, gives a gain G = c to the voltage Vz, and gives a gain G = b to the compensation signal Voff, whereby the voltages Vx, Vy, and Vz And a function of correcting the compensation signal Voff. It is preferable that the gain coefficient a and the gain coefficient b satisfy the relational expression of a = C1 / C2 × b. It is preferable that the gain coefficient c and the gain coefficient b satisfy the relational expression c = C3 / C2 × b.

  Here, C1 is the capacitance of the capacitor 22 of the conversion output circuits 20a and 20c, C2 is the capacitance of the capacitor 32 of the compensation signal output circuit 30, and C3 is the capacitance of the capacitor 22 of the conversion output circuit 20b. It is electric capacity. Thereby, the sensitivity difference between the voltages Vx and Vy and the compensation signal Voff due to the difference between the capacitance C1 of the capacitor 22 and the capacitance C2 of the capacitor 32 in the conversion output circuits 20a and 20c can be corrected. Similarly, the sensitivity difference between the voltage Vz and the compensation signal Voff due to the difference between the capacitance C3 of the capacitor 22 and the capacitance C2 of the capacitor 32 of the conversion output circuit 20b can be corrected. Accordingly, the output drift D (ie, a × D or c × D) included in the corrected voltages Vx, Vy, and Vz due to the leak current and the corrected compensation signal Voff (ie, b × D) ) Is substantially equal. Note that a = 1 means that the voltages Vx and Vy are not corrected. b = 1 means that the compensation signal Voff is not corrected. Similarly, c = 1 means that the voltage Vz is not corrected.

  The calculation unit has a function of calculating and outputting signals Fx, Fy, and Fz based on the voltages Vx, Vy, and Vz corrected by the gain correction unit and the compensation signal Voff corrected by the gain correction unit. The signal Fx is calculated by taking the difference between the voltage Vx corrected by the gain correction unit (that is, a × Vx) and the compensation signal Voff (b × Voff) corrected by the gain correction unit. Therefore, the output signal Fx is as follows.

Fx = a × Vx−b × Voff
= A * (Vxt + D) -b * Voff
= A × Vxt + a × D−b × Voff
≒ a x Vxt
Here, Vxt is a voltage component (true value) included in the voltage Vx and proportional to the amount of charge Qx accumulated.

Similarly, the signal Fy is calculated by taking the difference between the voltage Vy corrected by the gain correction unit (ie, a × Vy) and the compensation signal Voff (b × Voff) corrected by the gain correction unit. . Therefore, the output signal Fy is as follows.
Fy = a × Vy−b × Voff
= A * (Vyt + D) -b * Voff
= A × Vyt + a × D−b × Voff
≒ a x Vyt
Here, Vyt is a voltage component (true value) included in the voltage Vy and proportional to the amount of charge Qy accumulated.

Similarly, the signal Fz is calculated by taking the difference between the voltage Vz corrected by the gain correction unit (that is, c × Vz) and the compensation signal Voff (b × Voff) corrected by the gain correction unit. . Therefore, the output signal Fz is as follows.
Fz = c × Vz−b × Voff
= C * (Vzt + D) -b * Voff
= C * Vzt + c * D-b * Voff
≒ c x Vzt
Here, Vzt is a voltage component (true value) included in the voltage Vz and proportional to the amount of charge Qz accumulated.

  As described above, the output drift D (ie, a × D or c × D) that is included in the corrected voltages Vx, Vy, and Vz and is caused by the leakage current, and the corrected compensation signal Voff (b × Voff). ) Is substantially equal to (), the output drift D caused by the leakage current can be reduced (removed) from the corrected voltages Vx, Vy, and Vz. By having such a configuration, the arithmetic circuit 42b can output signals Fx, Fy, and Fz that are proportional to the accumulation amounts of the charges Qx, Qy, and Qz output from the charge output element 10b. Since the signals Fx, Fy, and Fz correspond to the triaxial force (shearing force and compression / tensile force) applied to the charge output element 10b, the force detection device 1b can detect the triaxial force applied to the charge output element 10a. Can be detected.

  As described above, the force detection device 1b according to the present invention includes the compensation signal output circuit 30 and the external force detection circuit 40b, so that the output resulting from the leakage current of the switching element 23 of the conversion output circuits 20a, 20b, and 20c. The drift D can be reduced. As a result, 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.

<Third Embodiment>
Next, a six-axis force detection device (force detection device) according to a third embodiment of the present invention will be described with reference to FIG. Hereinafter, the third embodiment will be described with a focus on differences from the first and second embodiments described above, and descriptions of similar matters will be omitted.
FIG. 6 is a perspective view schematically showing a third embodiment of the force detection device of the present invention. The six-axis force detection device (force detection device) 100 in FIG. 6 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 six-axis force detection device 100 is sandwiched between a first substrate 101, a second substrate 102 facing the first substrate 101, and the first substrate 101 and the second substrate 102 (provided). And four calculation units (not shown) connected to the four force detection devices 1b.

  As described above, the force detection device 1b has a function of detecting an external force along three axes (α (X) axis, β (Y) axis, γ (Z) axis) orthogonal to each other. Further, the force detection device 1b is sandwiched (provided) between the first substrate 101 and the second substrate 102 in a state where they all face the same direction. As illustrated, the force detection devices 1b are preferably arranged at equiangular intervals along the circumferential direction of the first substrate 101 or the second substrate 102. More preferably, they are arranged at equal intervals in a concentric manner with the center point of the substrate 102 as the center. Thus, by arranging the force detection device 1b, it is possible to detect the external force without deviation.

  When an external force is applied in which the relative positions of the first substrate 101 and the second substrate 102 are shifted in the Fx0 direction, the force detection devices 1b output signals Fx1, Fx2, Fx3, and Fx4, respectively. Similarly, when an external force is applied in which the relative positions of the first substrate 101 and the second substrate 102 are shifted in the Fy0 direction, the force detection devices 1b output signals Fy1, Fy2, Fy3, and Fy4, respectively. Further, when an external force is applied in which the relative positions of the first substrate 101 and the second substrate 102 are shifted in the Fz0 direction, the force detection devices 1b output signals Fz1, Fz2, Fz3, and Fz4, respectively.

The first substrate 101 and the second substrate 102 are capable of relative displacement rotating around the x axis, relative displacement rotating around the y axis, and relative displacement rotating around the z axis. Can be transmitted to the force detection device 1b.
Based on the signal output from each force detection device 1b, the arithmetic unit translates the translational force component Fx0 in the x-axis direction, the translational force component Fy0 in the y-axis direction, the translational force component Fz0 in the z-axis direction, and the rotational force around the x-axis. The component Mx, the rotational force component My around the y axis, and the rotational force component Mz around the z axis are calculated. Each force component can be obtained by the following equation.

Fx0 = Fx1 + Fx2 + Fx3 + Fx4
Fy0 = Fy1 + Fy2 + Fy3 + Fy4
Fz0 = Fz1 + Fz2 + Fz3 + Fz4
Mx = b × (Fz4-Fz2)
My = a × (Fz3-Fz1)
Mz = b * (Fx2-Fx4) + a * (Fy1-Fy3)
Here, a and b are constants.

As described above, the six-axis force detection device 100 includes the first substrate 101, the second substrate 102, the plurality of force detection devices 1b, and the calculation unit, and thus can detect the six-axis force.
In the illustrated configuration, the number of force detection devices 1b is four, but the present invention is not limited to this. The six-axis force detection device 100 can detect the six-axis force as long as it has at least three force detection devices 1b. When the number of force detection devices 1b is three, the number of force detection devices 1b is small, so that the weight of the six-axis force detection device 100 can be reduced. In the case where there are four force detection devices 1b as shown in the figure, the 6-axis force can be obtained by a very simple calculation as described above, so that the calculation unit can be simplified. Further, when there are six force detection devices 1b, it is possible to detect a six-axis force with higher accuracy.

<Fourth embodiment>
Next, a single arm robot according to a fourth embodiment of the present invention will be described with reference to FIG. Hereinafter, the fourth embodiment will be described with a focus on differences from the first, second, and third embodiments described above, and description of similar matters will be omitted.
FIG. 7 is a diagram showing an example of a single-arm robot using the force detection device 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. 6-axis force detection device (force detection device) 100 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 six-axis force detection device 100 has a function of detecting an external force applied to the end effector 530. By feeding back the six-axis force detected by the six-axis force detection device 100 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 six-axis force detection device 100. 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.
In the illustrated configuration, the arm coupling body 520 is configured by a total of five arms, but the present invention is not limited to this. When the arm connection body 520 is constituted by one arm, when constituted by 2 to 4 arms, when constituted by 6 or more arms, it is within the scope of the present invention.

<Fifth Embodiment>
Next, based on FIG. 8, the multi-arm robot which is 5th Embodiment of this invention is demonstrated. Hereinafter, the fifth embodiment will be described with a focus on differences from the first, second, third, and fourth embodiments described above, and description of similar matters will be omitted.
FIG. 8 is a diagram showing an example of a multi-arm robot using the force detection device 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 an end effector 640a provided on the distal end side of the first arm coupling body 620. The end effector 640b provided on the distal end side of the second arm connector 630, and between the first arm connector 620 and the end effector 640a and between the second arm connector 630 and the end effector 640b. The six-axis force detection device (force detection device) 100 of the present invention is provided.

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 end effectors 640a and 640b have a function of gripping an object. The end effector 640a has a first finger 641a and a second finger 642a. The end effector 640b has a first finger 641b and a second finger 642b. After the end effector 640a reaches the predetermined operating position by driving the first arm coupling body 620, the object can be gripped by adjusting the distance between the first finger 641a and the second finger 642a. it can. Similarly, after the end effector 640b reaches a 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 to hold the object. can do.

The six-axis force detection device 100 has a function of detecting an external force applied to the end effectors 640a and 640b. By feeding back the six-axis force detected by the six-axis force detection device 100 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 end effectors 640a and 640b with an obstacle by the six-axis force detected by the six-axis force detection device 100. 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.
In the configuration shown in the figure, there are a total of two arm connectors, but the present invention is not limited to this. The case where the multi-arm robot 600 includes three or more arm coupling bodies is also within the scope of the present invention.

<Sixth Embodiment>
Next, based on FIGS. 9 and 10, an electronic component inspection apparatus and an electronic component transport apparatus according to a sixth embodiment of the present invention will be described. Hereinafter, the sixth embodiment will be described with a focus on differences from the first, second, third, fourth, and fifth embodiments described above, and description of similar matters will be omitted.

FIG. 9 is a diagram showing an example of an electronic component inspection device and a component conveying device using the force detection device 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 that can move 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, a six-axis force detection device (force detection device) 100 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 conveying device 740 including a six-axis force detection device (force detection device) 100 of the present invention. The electronic component transport device 740 includes a gripping portion 741, a six-axis force detection device 100 connected to the gripping portion 741, a rotation shaft 742 connected to the gripping portion 741 via the six-axis force detection device 100, and a rotation shaft. A fine adjustment plate 743 is rotatably attached to 742. 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 six-axis force detection device 100 has a function of detecting a six-axis force applied to the grip portion 741. By feeding back the six-axis force detected by the six-axis force detection device 100 to the control device 750, the electronic component transport device 740 and the electronic component inspection device 700 can perform work more precisely. Further, the contact of the grip portion 741 to the obstacle or the like can be detected by the 6-axis force detected by the 6-axis force detection device 100. 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.
Further, the force detection devices 1a, 1b and the six-axis force detection device 100 of the present invention can be applied to various measuring devices such as a vibration meter, an accelerometer, a gravimeter, a dynamometer, a seismometer, and an inclinometer. Various measuring devices using the force detecting devices 1a and 1b and the six-axis force detecting device 100 of the invention are also within the scope of the present invention.

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

  DESCRIPTION OF SYMBOLS 1a, 1b ... Force detection apparatus 10a, 10b ... Charge output element (element) 11 ... Ground electrode layer 12 ... (1st) sensor 121 ... 1st piezoelectric material layer 122 ... Output electrode layer 123 ... 2nd piezoelectric material Layer 13 ... second sensor 131 ... third piezoelectric layer 132 ... output electrode layer 133 ... fourth piezoelectric layer 14 ... third sensor 141 ... fifth piezoelectric layer 142 ... output electrode layer 143 ... first 6 piezoelectric layers 20, 20a, 20b, 20c ... conversion output circuit 21 ... operational amplifier 22 ... capacitor 23 ... switching element 30 ... compensation signal output circuit 31 ... operational amplifier 32 ... capacitor 33 ... switching element 40a, 40b ... external force detection circuit 41a, 42a ... amplifier 41b ... AD converter 42b ... arithmetic circuit 43a ... differential amplifier 50 ... semiconductor substrate 60, 7 ... Interlayer insulating layer 71 ... Through hole 80a, 80b ... Distribution layer 100 ... Six-axis force detector (force detector) 101 ... First substrate 102 ... Second substrate 221, 321 ... Capacitor lower electrode layer 222, 322 ... Capacitor insulation layers 223, 323 ... Capacitor upper electrode layer 500 ... Single arm robot 510 ... Base 520 ... Arm coupling body 521 ... First arm 522 ... Second arm 523 ... Third arm 524 ... Fourth arm 525 ... 5th arm 530 ... End effector 531 ... 1st finger 532 ... 2nd finger 600 ... Multi-arm robot 610 ... Base 620 ... 1st arm coupling body 621 ... 1st arm 622 ... 2nd arm 630 ... 2nd arm coupling body 631 ... 1st arm 632 ... 2nd arm 640a ... 1st end effect 641a ... first finger 642a ... second finger 640b ... second end effector 641b ... first finger 642b ... second finger 700 ... electronic component inspection device 710 ... base 711 ... electronic component 712u ... upstream side Stage 712d ... downstream stage 713 ... imaging device 714 ... inspection table 720 ... support table 731 ... Y stage 732 ... arm portion 733 ... X stage 734 ... imaging camera 740 ... electronic component transport device 741 ... gripping portion 742 ... rotating shaft 743 ... Fine adjustment plate 744x, 744y, 744θ ... piezoelectric motor 750 ... control device CA1 ... first crystal axis CA2 ... second crystal axis CA3 ... third crystal axis CA4 ... fourth crystal axis CA5 ... fifth crystal axis CA6: sixth crystal axis Fx0, Fy0, Fz0: translational force component Fx1, Fx2, Fx3 Fx4, Fy1, Fy2, Fy3, Fy4, Fz1, Fz2, Fz3, Fz4 ... Signal Q, Qx, Qy, Qz ... Charge Mx, My, Mz ... Rotational force components V, Vx, Vy, Vz ... Voltage Voff ... For compensation signal

The present invention, force detection device, and relates to a robot with the force detector.

Claims (13)

An element that outputs electric charge according to the external force received;
A conversion output circuit having a first switching element and a first capacitor, converting the charge into a voltage and outputting the voltage;
A compensation signal output circuit having a second switching element and a second capacitor and outputting a compensation signal;
An external force detection circuit that detects the external force based on the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit;
The force detection device according to claim 1, wherein a capacitance of the second capacitor is smaller than a capacitance of the first capacitor.   The force detection according to claim 1, wherein C2 / C1 is 0.1 to 0.8, where C1 is the capacitance of the first capacitor and C2 is the capacitance of the second capacitor. apparatus. The first switching element and the second switching element are semiconductor switching elements that generate a leakage current,
The first switching element and the second switching element are mounted on the same semiconductor substrate so that the leakage current of the first switching element and the leakage current of the second switching element are linked. And
The force detection device according to claim 1, wherein the compensation signal output circuit detects the leakage current of the second switching element and outputs the detected leakage current as the compensation signal. The external force detection circuit includes a gain correction unit that performs correction by giving a gain to at least one of the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit. ,
4. The force detection according to claim 1, wherein the external force detection circuit detects the external force by taking a difference between the voltage corrected by the gain correction unit and the compensation signal. 5. apparatus. The element is configured by laminating a plurality of ground electrode layers grounded to the ground and at least three sensors,
The force detection device according to any one of claims 1 to 4, wherein force detection directions of the sensors are orthogonal to each other. At least one of the sensors includes an X-cut crystal;
The force detection device according to claim 5, wherein at least two of the sensors include a Y-cut crystal. Each of the sensors 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 force detection device according to claim 5 or 6, wherein the first crystal axis of the first piezoelectric layer faces a direction opposite to the direction of the second crystal axis of the second piezoelectric layer. .   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 first substrate and a second substrate facing the first substrate,
9. The force detection device according to claim 1, wherein the element is provided between the first substrate and the second substrate. 10. The force detection device has a plurality of the elements,
The force detection device according to claim 9, wherein the elements are arranged at equiangular intervals along a circumferential direction of the first substrate or the second substrate. 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:
An element that outputs electric charge according to the external force;
A conversion output circuit having a first switching element and a first capacitor, converting the charge into a voltage and outputting the voltage;
A compensation signal output circuit having a second switching element and a second capacitor and outputting a compensation signal;
An external force detection circuit that detects the external force based on the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit;
The robot according to claim 1, wherein a capacitance of the second capacitor is smaller than a capacitance of the first capacitor. A motor,
A gripper that is driven by the motor and grips an electronic component;
A force detection device that detects an external force applied to the gripping portion;
The force detection device includes:
An element that outputs electric charge according to the external force;
A conversion output circuit having a first switching element and a first capacitor, converting the charge into a voltage and outputting the voltage;
A compensation signal output circuit having a second switching element and a second capacitor and outputting a compensation signal;
An external force detection circuit that detects the external force based on the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit;
The electronic component transport apparatus according to claim 1, wherein a capacitance of the second capacitor is smaller than a capacitance of the first capacitor. A motor,
A gripper that is driven by the motor and grips an electronic component;
An inspection unit for inspecting the electronic component, and a force detection device for detecting an external force applied to the gripping unit,
The force detection device includes:
An element that outputs electric charge according to the external force;
A conversion output circuit having a first switching element and a first capacitor, converting the charge into a voltage and outputting the voltage;
A compensation signal output circuit having a second switching element and a second capacitor and outputting a compensation signal;
An external force detection circuit that detects the external force based on the voltage output from the conversion output circuit and the compensation signal output from the compensation signal output circuit;
2. The electronic component inspection apparatus according to claim 1, wherein a capacitance of the second capacitor is smaller than a capacitance of the first capacitor.

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