JP2018017592A - Charge amplification circuit, physical quantity sensor device and robot - Google Patents

Abstract

Provided are a charge amplification circuit, a physical quantity sensor device, and a robot that can reduce drift due to leakage current. An electric charge amplifying circuit includes an attenuating circuit for lowering a voltage of a voltage source, a resistance element for generating a current by applying the voltage dropped by the attenuating circuit, and a charge amplifying unit to which the current is input. And The charge amplifying unit has an inverting input terminal and a non-inverting input terminal, and amplifies an electric potential difference between the inverting input terminal and the non-inverting input terminal; and an output terminal of the operational amplifier and the inverting terminal. A capacitor connected between the input terminal and the input terminal. [Selection diagram] Fig. 1

Description

  The present invention relates to a charge amplification circuit, a physical quantity sensor device, and a robot.

  2. Description of the Related Art Conventionally, in various fields, physical quantity sensors that generate a charge having a magnitude corresponding to a received physical quantity have been actively used. Usually, the electric charge from the physical quantity sensor is converted into a voltage signal by an amplifier circuit and used. Such an amplifier circuit includes, for example, an operational amplifier having an inverting input terminal, a non-inverting input terminal and an output terminal, and a capacitor (integrating capacitor) connected in parallel between the inverting input terminal and the output terminal. The circuit is general, and according to such a circuit, the charge from the physical quantity sensor input from the inverting input terminal is charged in the capacitor, and is obtained from the voltage of the capacitor (that is, the quotient value of the charge by the capacitor). The voltage can be output from the output terminal.

  However, there is usually a leakage current at the inverting input terminal of the operational amplifier, which is charged to the capacitor and the voltage at the output terminal fluctuates away from the initial value when the amplifier circuit is operated repeatedly for a long time. Will occur. If measurement of a physical quantity is started with drift occurring, this “drift” becomes an error in measurement, and the physical quantity cannot be detected accurately. For this reason, conventionally, a switching element connected in parallel with the capacitor is provided, and before starting the measurement of the physical quantity, the switching element is closed and both ends of the capacitor are short-circuited, and the charged “drift” charge is reset to zero. It was.

  Further, as a method of reducing “drift”, the configuration described in Patent Document 1 is known. In the charge amplifier circuit described in Patent Document 1, the compensation current flows into the amplifier circuit through the capacitor, so that the leakage current is canceled out and the drift is reduced.

JP 2009-58290 A

  However, in the configuration of Patent Document 1, a film capacitor having a large insulation resistance value is used as the capacitor. This film capacitor is merely a capacitor and is not supposed to be used as a substitute for a resistance element. The insulation resistance value variation (individual difference) is larger than that of the resistance element, and the temperature of the insulation resistance value There is no control over characteristics and aging. For this reason, the compensation current deviates from a magnitude suitable for canceling the leakage current, and it becomes difficult to accurately cancel the input leakage current by the compensation current.

  An object of the present invention is to provide a charge amplification circuit, a physical quantity sensor device, and a robot that can reduce drift due to leakage current.

Such an object is achieved by the present invention described below.
The charge amplification circuit of the present invention includes an attenuation circuit that drops the voltage of the voltage source,
A resistance element that generates a current by applying the voltage dropped in the attenuation circuit;
And a charge amplifying unit to which the current is input.
As a result, a charge amplifier circuit capable of reducing drift due to leakage current is obtained.

In the charge amplification circuit of the present invention, the charge amplification unit has an inverting input terminal and a non-inverting input terminal, and amplifies a potential difference between the inverting input terminal and the non-inverting input terminal;
It is preferable to have a capacitor connected between the output terminal of the operational amplifier and the inverting input terminal.
This simplifies the configuration of the charge amplification circuit.

In the charge amplifier circuit of the present invention, it is preferable that the resistance value of the resistance element is in a range of 1 × 10 ⁸ Ω to 1 × 10 ¹¹ Ω.
Thereby, what can grasp | ascertain the resistance value, a temperature characteristic, etc. correctly can be used as a resistance element.

In the charge amplification circuit of the present invention, it is preferable that the attenuation rate of the attenuation circuit is in a range of 1 / 10,000 or more and 1/10 or less.
Thereby, what can grasp | ascertain the resistance value, a temperature characteristic, etc. correctly can be used as a resistance element.

The physical quantity sensor device of the present invention includes a charge amplification circuit of the present invention,
A physical quantity sensor connected to the charge amplifying circuit and generating a charge corresponding to the physical quantity.
Thereby, the effect of the charge amplification circuit of the present invention can be enjoyed, and a highly reliable physical quantity sensor can be obtained.

The physical quantity sensor device of the present invention preferably includes a voltage source circuit that controls the voltage of the voltage source based on the temperature of the charge amplification circuit.
Thereby, the drift by leakage current can be reduced more effectively.

The physical quantity sensor device of the present invention preferably includes a voltage source circuit that controls the voltage of the voltage source based on an output of the charge amplification circuit when the physical quantity sensor does not receive a physical quantity.
Thereby, the drift by leakage current can be reduced more effectively.

In the physical quantity sensor device of the present invention, it is preferable that the physical quantity sensor is a force sensor.
This makes it easy to apply the physical quantity sensor device to a robot.

In the physical quantity sensor device of the present invention, it is preferable that the physical quantity sensor is a torque sensor.
This makes it easy to apply the physical quantity sensor device to a robot.

A robot according to the present invention includes the charge amplification circuit according to the present invention.
Thereby, the effect of the charge amplification circuit of the present invention can be enjoyed, and a highly reliable robot can be obtained.

1 is a circuit diagram illustrating a physical quantity sensor device according to a first embodiment of the present invention. 3 is a graph showing an example of an output from the charge amplifier circuit shown in FIG. 1. It is a circuit diagram of a physical quantity sensor device according to a second embodiment of the present invention. It is a top view of the physical quantity sensor which the physical quantity sensor apparatus shown in FIG. 3 has. It is sectional drawing of the sensor element which the physical quantity sensor shown in FIG. 4 has. It is a perspective view of the robot which concerns on 3rd Embodiment of this invention.

  Hereinafter, a charge amplification circuit, a physical quantity sensor device, and a robot of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<First Embodiment>
FIG. 1 is a circuit diagram showing a physical quantity sensor device according to the first embodiment of the present invention. FIG. 2 is a graph showing an example of an output from the charge amplifier circuit shown in FIG.

  A physical quantity sensor device 1 shown in FIG. 1 includes a charge amplification circuit 2 and a physical quantity sensor 3 that is connected to the charge amplification circuit 2 and generates a charge corresponding to the physical quantity. In addition, the charge amplifier circuit 2 includes an attenuation circuit 21 that drops the voltage Va of the voltage source circuit 4 (voltage source), a resistance element 23 that generates a current when the voltage Va dropped by the attenuation circuit 21 is applied, and a current Charge amplifying unit 22 to which is inputted. The charge amplifying unit 22 includes an inverting input terminal 221a, a non-inverting input terminal 221b, and an output terminal 221c, and an operational amplifier 221 (an operational amplifier) that amplifies a potential difference between the inverting input terminal 221a and the non-inverting input terminal 221b. And a capacitor 222 (integrating capacitor) connected between the output terminal 221c and the inverting input terminal 221a of the operational amplifier 221. In such a physical quantity sensor device 1, the charge signal output from the physical quantity sensor 3 is charged in the capacitor 222, and the voltage obtained from the voltage of the capacitor 222 (that is, the quotient value of the charge by the capacitor 222) is output from the output terminal 221c. Is done.

  Here, normally, there is a leakage current at the inverting input terminal 221a of the operational amplifier 221, and this leakage current is charged in the capacitor 222, and the physical quantity sensor device 1 is repeatedly operated for a long time, whereby the voltage at the output terminal 221c is initialized. A “drift” phenomenon occurs that fluctuates away from the value. If measurement of a physical quantity is started with drift occurring, this drift becomes a measurement error, and there is a problem that the physical quantity cannot be detected accurately. However, in the charge amplifying circuit 2, the leakage current is canceled by the minute compensation current generated by applying the voltage dropped by the attenuation circuit 21 to the resistance element 23 flowing into the inverting input terminal 221a. Therefore, the aforementioned drift can be reduced. In the charge amplifier circuit 2, by using the low voltage dropped by the attenuation circuit 21, not the insulation resistance of the film capacitor having the extremely high resistance value as in Patent Document 1, but the resistance element 23 is used to correspond to the leakage current. A minute compensation current can be generated. Unlike the insulation resistance of the capacitor, the resistance element 23 can use a resistance whose resistance value varies, temperature characteristics, and aging characteristics are guaranteed, so that the compensation current to be generated can be accurately controlled. Therefore, the physical quantity sensor device 1 that can enjoy the effect of the charge amplification circuit 2 can exhibit high reliability. Hereinafter, such a physical quantity sensor device 1 will be described in detail.

<Physical quantity sensor>
The physical quantity sensor 3 generates a charge corresponding to the physical quantity to be measured. The physical quantity sensor 3 is not particularly limited, but is a crystal such as quartz, topaz, barium titanate, lead titanate, lead zirconate titanate (PZT), lithium niobate, lithium tantalate, etc., PVDF (polyfluoride) A piezoelectric sensor using the piezoelectric effect of a piezoelectric organic film such as vinylidene) is preferable. Thereby, a high impedance charge signal from the piezoelectric sensor can be converted into a low impedance voltage signal by the charge amplification circuit 2. Among the piezoelectric sensors as described above, a piezoelectric sensor using quartz is particularly preferable. This is because a piezoelectric sensor using quartz has excellent characteristics such as a wide dynamic range, high rigidity, high natural frequency, and high load resistance.

  Further, the piezoelectric sensor is not particularly limited, and examples thereof include an acceleration sensor, an angular velocity sensor, a pressure sensor, a force sensor, a torque sensor, and the like. Among these, a force sensor and a torque sensor are particularly preferable. . By using the physical quantity sensor 3 as a force sensor or a torque sensor, the physical quantity sensor device 1 can be easily applied to a robot as described in a third embodiment to be described later.

  The physical quantity sensor 3 is not limited to the above as long as it generates a charge corresponding to the physical quantity when a physical quantity to be measured is added. For example, a sensor that does not use the piezoelectric effect may be used. Good. Moreover, it does not specifically limit as a physical quantity to detect, For example, you may detect light.

  One electrode of such a physical quantity sensor 3 is connected to the inverting input terminal 221a, and the other electrode is connected to the ground.

<Charge amplification circuit>
As shown in FIG. 1, the operational amplifier 221 has an inverting input terminal 221a, a non-inverting input terminal 221b, and an output terminal 221c, and amplifies the potential difference between the inverting input terminal 221a and the non-inverting input terminal 221b. The amplified voltage is output to the output terminal 221c. The inverting input terminal 221a is connected to one electrode of the physical quantity sensor 3, and the charge from the physical quantity sensor 3 flows into the inverting input terminal 221a. On the other hand, the non-inverting input terminal 221b is connected to the ground. A capacitor 222 is connected in parallel between the inverting input terminal 221a and the output terminal 221c. When a charge is generated from the physical quantity sensor 3, a potential difference having the same polarity as that of the charge is generated between the inverting input terminal 221a and the non-inverting input terminal 221b. The operational amplifier 221 inverts and amplifies the potential difference and outputs it to the output terminal 221c. As a result, a charge having a polarity opposite to the charge generated from the physical quantity sensor 3 is generated at the electrode on the output end 221c side of the capacitor 222. At this time, a reverse polarity, that is, a charge having the same polarity as that generated from the physical quantity sensor 3 is further induced in the electrode on the inverting input terminal 221 a side of the capacitor 222. It is done by moving. Since the potential difference between the inverting input terminal 221a and the non-inverting input terminal 221b decreases due to the movement of the charges, the inverting amplification operation of the operational amplifier 221 continues until the potential difference becomes substantially zero (0), and the physical quantity sensor 3 All of the electric charges generated from the above move to the capacitor 222. As a result, the voltage generated at both ends of the capacitor 222 is a voltage obtained by dividing the generated charge by the capacitance of the capacitor 222. Thus, since the charge amplifying unit 22 includes the operational amplifier 221 and the capacitor 222, the configuration of the charge amplifying unit 22 (charge amplifying circuit 2) is simplified.

  A switching element 223 is connected in parallel between the inverting input terminal 221a and the output terminal 221c in the same manner as the capacitor 222. With this switching element 223, the charge for the drift charged in the capacitor 222 can be reset to zero (0). Specifically, when the switching element 223 is off, the charge output from the physical quantity sensor 3 is stored in the capacitor 222, and a voltage having a magnitude corresponding to the physical quantity received by the physical quantity sensor 3 is output from the output terminal 221c. The On the other hand, when the switching element 223 is turned on, the terminals of the capacitor 222 are short-circuited, so that the charge stored in the capacitor 222 is discharged. Thereby, the charge for the drift charged in the capacitor 222 can be reset to zero.

  The attenuation circuit 21 and the resistance element 23 are circuits for generating a current Ia for canceling the leakage current from the voltage Va, and flowing the current into the inverting input terminal 221a. Note that the current Ia has the same absolute value as the leakage current but has the opposite polarity. With such a configuration, the leakage current can be canceled by the current Ia, and the above-described drift can be reduced. Therefore, the physical quantity sensor device 1 can exhibit excellent detection accuracy. In particular, by attenuating the voltage Va using the attenuation circuit 21 and the resistance element 23, the resistance of the resistance element 23 can be made smaller than the conventional one (for example, the configuration of Patent Document 1 described above). Therefore, the resistance element 23 can be used so that its resistance value, temperature characteristics, etc. can be accurately grasped, the current Ia can be generated more accurately, and the leakage current can be offset by the current Ia. .

  Here, the magnitude of the voltage Va is not particularly limited, and can be, for example, −5 V or more and +5 V or less. The voltage Va is applied from the voltage source circuit 4. The voltage source circuit 4 adjusts the magnitude of the voltage Va applied to the terminal 24 according to the magnitude of the leakage current. Thereby, the leakage current can be accurately canceled by the current Ia.

  For example, the magnitude of the leakage current varies depending on the temperature. Normally, the leakage current increases as the temperature increases. Therefore, the voltage source circuit 4 is preferably configured to control the magnitude of the voltage Va applied to the terminal 24 based on the temperature of the charge amplifier circuit 2. Specifically, for example, the relationship between the temperature of the charge amplifier circuit 2 and the magnitude of the leakage current is stored in advance as a table (relational expression), and further, a temperature sensor (not shown) that detects the temperature of the charge amplifier circuit 2. The voltage Va applied to the terminal 24 is preferably controlled based on the temperature of the charge amplifier circuit 2 detected by the temperature sensor and the table. Thereby, the drift by leakage current can be reduced more effectively.

  As another configuration, the voltage source circuit 4 is based on the output of the charge amplification circuit 2 when the physical quantity sensor 3 is not receiving a physical quantity, in other words, based on the output caused by the leakage current, for example. It is preferable to be configured so as to control the magnitude of the voltage Va applied to. For example, when the output of the charge amplification circuit 2 (the output of the terminal 25) when the physical quantity sensor 3 does not receive a physical quantity increases with time as shown in FIG. 2, the power supply is set so that this output becomes constant. What is necessary is just to control the magnitude | size of the voltage Va. Thereby, the drift by leakage current can be reduced more effectively.

  The attenuation circuit 21 is arranged between the terminal 24 to which the voltage Va is applied and the resistance element 23, and is a circuit that attenuates the voltage Va with a predetermined attenuation rate. The attenuation circuit 21 has two resistance elements 211 and 212 connected in series, one end connected to the terminal 24 and the other end connected to the ground. In such an attenuation circuit 21, when the resistance of the resistance element 211 is R1 and the resistance of the resistance element 212 is R2, the power supply voltage Va can be attenuated with an attenuation factor of R2 / (R1 + R2). Here, the attenuation factor of the attenuation circuit 21 is not particularly limited, but is preferably 1 / 10,000 or more and 1/10 or less, and more preferably 1/100 or more and 1/20 or less. By setting the attenuation rate within such a range, the voltage Va can be sufficiently lowered by the attenuation circuit 21 in a range where it is not buried in noise, and the resistance value of the resistance element 23 can be suppressed to that extent. For this reason, as the resistance element 23, one that can accurately grasp its resistance value, temperature characteristics and the like can be used.

  The two resistance elements 211 and 212 are not particularly limited, but it is preferable to use one that can accurately grasp the resistance value, temperature characteristics, and the like. Thereby, it is possible to accurately grasp the attenuation rate. As such resistance elements 211 and 212, for example, carbon film resistors, metal film resistors, metal oxide film resistors, winding resistors, enamel resistors, cement resistors, and the like can be used.

On the other hand, the resistance value of the resistance element 23 is not particularly limited, for example, 1 × 10 ⁸ Omega or more, preferably 1 × less ^{10 11 Ω, 1 × 10 8} Ω or more, 1 × ^{10 10} Omega less It is more preferable that By setting the resistance value in such a range, a sufficiently small current Ia corresponding to the leakage current can be generated. In addition, as the resistance element 23 having a resistance value in such a range, an element that can accurately grasp the resistance value, temperature characteristics, and the like can be used. Currently, when the resistance value is 1 × 10 ¹² Ω or more, it is technically and costly difficult to use a resistance element 23 that can accurately grasp the resistance value, temperature characteristics, and the like.

  Such a resistance element 23 is not particularly limited, but preferably has a high resistance and low temperature characteristics. For example, a carbon film resistor, a metal film resistor, a metal oxide film resistor, a winding resistor, a hollow resistor, and the like. Resistors, cement resistors, etc. can be used.

Second Embodiment
FIG. 3 is a circuit diagram of a physical quantity sensor device according to the second embodiment of the present invention. 4 is a plan view of a physical quantity sensor included in the physical quantity sensor device shown in FIG. FIG. 5 is a cross-sectional view of a sensor element included in the physical quantity sensor shown in FIG.

  The physical quantity sensor device according to the present embodiment is the same as the physical quantity sensor device of the first embodiment described above except that the physical quantity sensor is a composite sensor that serves both as a force sensor and a torque sensor.

  In the following description, the physical quantity sensor device according to the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. 3 to 5, the same reference numerals are given to the same configurations as those of the above-described embodiment.

  The physical quantity sensor 3 is a composite sensor that also serves as a force sensor and a torque sensor, and has six axial forces (translational force components in the X, Y, and Z axis directions orthogonal to each other and rotational force components around the X, Y, and Z axes). It has a function to detect. As shown in FIG. 4, the physical quantity sensor 3 includes two substrates 31 and 32 and four sensor elements 33 sandwiched between the substrates 31 and 32. The two substrates 31 and 32 are fixed by pressurizing bolts (not shown). The four sensor elements 33 are arranged at equal intervals (90 ° intervals) along the outer peripheral portions of the substrates 31 and 32.

  Each sensor element 33 has a function of outputting three charges Qx, Qy, and Qz in accordance with external forces applied along three axes (X axis, Y axis, and Z axis) orthogonal to each other. . As shown in FIG. 5, the sensor element 33 includes four ground electrode layers 34 grounded to the ground, a first sensor 35 that outputs a charge Qy according to an external force (shearing force) parallel to the Y axis, and Z A second sensor 36 that outputs a charge Qz according to an external force (compression / tensile force) parallel to the axis, and a third sensor 37 that outputs a charge Qx according to an external force (shear force) parallel to the X axis. The ground electrode layer 34 and the sensors 35, 36, and 37 are alternately stacked.

  The first sensor 35 includes a first piezoelectric layer 351 having a first crystal axis CA1 oriented in the negative direction of the Y axis and a second piezoelectric layer 353 having a second crystal axis CA2 oriented in the positive direction of the Y axis. And an output electrode layer 352 that is provided between the first piezoelectric layer 351 and the second piezoelectric layer 353 and outputs a charge Qy. In addition, the 1st piezoelectric material layer 351 and the 2nd piezoelectric material layer 353 can be comprised with a Y cut quartz plate, for example.

  The second sensor 36 includes a third piezoelectric layer 361 having a third crystal axis CA3 oriented in the positive direction of the Z axis and a fourth piezoelectric layer 363 having a fourth crystal axis CA4 oriented in the negative direction of the Z axis. And an output electrode layer 362 that is provided between the third piezoelectric layer 361 and the fourth piezoelectric layer 363 and outputs a charge Qz. In addition, the 3rd piezoelectric material layer 361 and the 4th piezoelectric material layer 363 can be comprised with an X cut quartz plate, for example.

  The third sensor 37 includes a fifth piezoelectric layer 371 having a fifth crystal axis CA5 oriented in the negative direction of the X axis and a sixth piezoelectric layer 373 having a sixth crystal axis CA6 oriented in the positive direction of the X axis. And an output electrode layer 372 that is provided between the fifth piezoelectric layer 371 and the sixth piezoelectric layer 373 and outputs a charge Qx. In addition, the 5th piezoelectric material layer 371 and the 6th piezoelectric material layer 373 can be comprised with a Y cut quartz plate, for example.

  The physical quantity sensor 3 has been described above. As shown in FIG. 3, in the physical quantity sensor device 1 of the present embodiment, three charge amplification circuits 2 are connected to one sensor element 33, and these three charge amplification circuits 2 are connected to charges Qx, Qy, and Qz. It corresponds. In addition, a voltage source circuit 4 is connected to each charge amplifier circuit 2 as in the first embodiment described above. The voltages Vx, Vy, and Vz output from each charge amplifier circuit 2 are input to the external force detection circuit 6, and the external force detection circuit 6 converts the translational force component in the X-axis direction, the translational force component in the Y-axis direction, and Z A translational force component in the axial direction, a rotational force component around the X axis, a rotational force component around the Y axis, and a rotational force component around the Z axis are detected.

  Also according to the second embodiment, the same effects as those of the first embodiment described above can be exhibited. The physical quantity sensor of the present embodiment is a composite sensor that serves as both a force sensor and a torque sensor. However, the physical quantity sensor is not particularly limited, and may be a force sensor or a torque sensor. It may be a sensor that detects other physical quantities.

<Third Embodiment>
FIG. 6 is a perspective view of a robot according to the third embodiment of the present invention.

  The robot 9 shown in FIG. 6 is a robot that can be used in a manufacturing process for manufacturing industrial products such as precision equipment. As shown in the figure, the robot 9 includes, for example, a base 91 fixed to a floor or a ceiling, an arm 92 rotatably connected to the base 91, an arm 93 rotatably connected to the arm 92, An arm 94 pivotably connected to the arm 93, an arm 95 pivotally connected to the arm 94, an arm 96 pivotally connected to the arm 95, and a pivotally connected to the arm 96 And a control unit 98 that controls the driving of the arms 92 to 97. Further, the arm 97 is provided with a hand connection portion, and an end effector 99 corresponding to the work to be executed by the robot 9 is attached to the hand connection portion.

  Such a robot 9 is provided with a physical quantity sensor device 1 that detects an external force applied to the end effector 99. The robot 9 can perform more precise work by feeding back the force detected by the physical quantity sensor device 1 to the control unit 98. Further, the robot 9 can detect contact of the end effector 99 with an obstacle by the force detected by the physical quantity sensor device 1. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that have been difficult with conventional position control can be easily performed, and the robot 9 can execute the work more safely. In addition to this, for example, the physical quantity sensor device 1 as a torque sensor device may be arranged at a joint portion of each arm 92, 93, 94, 95, 96, 97, or a physical quantity as a force sensor device. The sensor device 1 may be disposed at the fingertip of the end effector 99.

  Thus, since the robot 9 has the physical quantity sensor device 1 described above and the physical quantity sensor device has the charge amplification circuit 2, the robot 9 can enjoy the effects of the charge amplification circuit 2 described above, and can be trusted. The robot 9 has a high performance.

  The effect of the first embodiment described above can also be exhibited by the third embodiment. In addition, it does not specifically limit as a structure of a robot, For example, the number of arms may differ from this embodiment. The robot may be a so-called SCARA robot or double-arm robot.

  The charge amplification circuit, the physical quantity sensor device, and the robot of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each unit is an arbitrary function having the same function. It can be replaced with the configuration of In addition, any other component may be added to the present invention. Moreover, you may combine each embodiment suitably.

  DESCRIPTION OF SYMBOLS 1 ... Physical quantity sensor apparatus, 2 ... Charge amplification circuit, 21 ... Attenuation circuit, 211, 212 ... Resistance element, 22 ... Charge amplification part, 221 ... Operational amplifier, 221a ... Inverting input terminal, 221b ... Non-inverting input terminal, 221c ... Output terminal, 222, capacitor, 223, switching element, 23, resistance element, 24, 25 ... terminal, 3 ... physical quantity sensor, 31, 32 ... substrate, 33 ... sensor element, 34 ... ground electrode layer, 35 ... first sensor 351: First piezoelectric layer, 352: Output electrode layer, 353: Second piezoelectric layer, 36: Second sensor, 361: Third piezoelectric layer, 362: Output electrode layer, 363: Fourth piezoelectric layer 37 ... third sensor, 371 ... fifth piezoelectric layer, 372 ... output electrode layer, 373 ... sixth piezoelectric layer, 4 ... voltage source circuit, 6 ... external force detection circuit, 9 ... robot, 91 ... base, 92 , 3, 94, 95, 96, 97 ... arm, 98 ... control unit, 99 ... end effector, CA1 ... first crystal axis, CA2 ... second crystal axis, CA3 ... third crystal axis, CA4 ... fourth crystal axis, CA5 ... fifth crystal axis, CA6 ... sixth crystal axis, Ia ... current, Qx, Qy, Qz ... charge, Va ... power supply voltage, Vx, Vy, Vz ... voltage

Claims (10)

An attenuation circuit for dropping the voltage of the voltage source;
A resistance element that generates a current by applying the voltage dropped in the attenuation circuit;
A charge amplifying circuit comprising: a charge amplifying unit to which the current is input; The charge amplification section has an inverting input terminal and a non-inverting input terminal, and an operational amplifier that amplifies a potential difference between the inverting input terminal and the non-inverting input terminal;
The charge amplification circuit according to claim 1, further comprising a capacitor connected between an output terminal of the operational amplifier and the inverting input terminal. 3. The charge amplification circuit according to claim 1, wherein a resistance value of the resistance element is in a range of 1 × 10 ⁸ Ω to 1 × 10 ¹¹ Ω.   4. The charge amplifying circuit according to claim 1, wherein an attenuation factor of the attenuation circuit is in a range of 1 / 10,000 or more and 1/10 or less. 5. The charge amplification circuit according to any one of claims 1 to 4,
A physical quantity sensor device comprising: a physical quantity sensor connected to the charge amplification circuit and generating a charge corresponding to the physical quantity.   The physical quantity sensor device according to claim 5, further comprising a voltage source circuit that controls a voltage of the voltage source based on a temperature of the charge amplification circuit.   The physical quantity sensor device according to claim 5, further comprising a voltage source circuit that controls a voltage of the voltage source based on an output of the charge amplification circuit when the physical quantity sensor does not receive a physical quantity.   The physical quantity sensor device according to claim 5, wherein the physical quantity sensor is a force sensor.   The physical quantity sensor device according to claim 5, wherein the physical quantity sensor is a torque sensor.   A robot comprising the charge amplification circuit according to any one of claims 1 to 4.

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