JP2000329785A - Acceleration detecting device provided with piezoelectric acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration detecting device provided with a piezoelectric acceleration sensor capable of accurately detecting acceleration which vibrates at a frequency of 0.1 Hz or less. SOLUTION: This acceleration detecting device comprises one electrode 4b or more on the surface of a piezoelectric ceramic substrate 4a and one counter electrode 4c or more to counter the electrode 4b for detection on the back surface. The output of the piezoelectric acceleration sensor 4 in which spontaneous polarization charge is generated in the electrode 4b for detection at the time when the piezoelectric ceramic substrate 4a is bent by the action of acceleration is amplified with an offset voltage as a center by a voltage amplifier 2. An ultra-high resistor R8 is parallelly connected between the signal input terminal of the voltage amplifier 2 and a ground. The resistance value of the ultra-high resistor R8 is set at a value capable of constituting a current- voltage converting circuit which converts current outputted from the piezoelectric acceleration sensor 4 into voltage at the time when the piezoelectric acceleration sensor 4 detects acceleration which vibrates at a frequency of 0.1 Hz or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration detecting device provided with a piezoelectric acceleration sensor using a piezoelectric ceramic substrate.

[0002]

2. Description of the Related Art A piezoelectric acceleration sensor has one or more detection electrodes on the front surface of a piezoelectric ceramic substrate and one or more counter electrodes on the back surface facing the detection electrodes. When the piezoelectric ceramic substrate is bent, spontaneous polarization charges are generated in the detection electrodes. This type of piezoelectric acceleration sensor is a uniaxial acceleration sensor capable of detecting acceleration in one direction, a three-axis acceleration sensor capable of detecting acceleration in three-dimensional directions, and the like, and its basic principle and basic structure are described in International Publication WO 93/02342 ( PCT / JP92 / 0088
No. 2) and the like.

[0003] An acceleration detecting device provided with a conventional piezoelectric acceleration sensor amplifies an output voltage of the piezoelectric acceleration sensor around a predetermined offset voltage and outputs the amplified voltage as a voltage signal; An offset reference voltage generating circuit for generating an offset reference voltage serving as a reference. Although the output of the piezoelectric acceleration sensor has positive and negative polarities, in order to facilitate signal processing, the reference voltage for amplification of the amplifier circuit is shifted from 0 V to one polarity (generally positive polarity) by an offset voltage. Is displaced or moved.

[0004]

In the case where acceleration is detected using an acceleration detecting device provided with a conventional piezoelectric acceleration sensor, if the vibration or acceleration becomes an extremely low frequency of 0.1 Hz or less, the vibration or acceleration is reduced. It turned out to be undetectable.

An object of the present invention is to provide an acceleration detecting device provided with a piezoelectric acceleration sensor capable of accurately detecting acceleration oscillating at a frequency of 0.1 Hz or less.

[0006]

The vibration or acceleration is 1H.
When the frequency becomes extremely low below z, there may be a plurality of causes that the conventional acceleration detecting device cannot accurately detect vibration or acceleration. One cause is a change in characteristics of the piezoelectric acceleration sensor, as described in detail in Japanese Patent Application No. 10-203499, which is a prior application of the present applicant. That is, the basic structure of a piezoelectric acceleration sensor in which a dielectric (piezoelectric ceramic substrate) is arranged between the detection electrode and the counter electrode is the same as that of a capacitor. For example, the capacitance C of a piezoelectric acceleration sensor having a certain shape is about 1 nF. The impedance Z of the piezoelectric acceleration sensor is Z
= １ ／ πfC. Therefore, the impedance Z of the piezoelectric acceleration sensor increases as the frequency decreases, and for example, becomes about 1.6 GΩ at a frequency of 0.1 Hz. As described above, when the impedance value of the piezoelectric acceleration sensor increases, the output of the piezoelectric acceleration sensor flows into the offset reference voltage generating circuit side having a low impedance, which means that the vibration or acceleration is very low frequency of 1 Hz or less. , The vibration or acceleration cannot be detected accurately.

In order to eliminate this cause, Japanese Patent Application No.
According to the invention described in JP-A-203499, an ultra-high resistance element is disposed between the output point of the offset reference voltage generation circuit and the signal input terminal of the amplifier circuit, and the resistance of the ultra-high resistance element is set to 1 Hz or less by the piezoelectric acceleration sensor The impedance is set to be larger than the impedance of the piezoelectric acceleration sensor when detecting the acceleration oscillating at the frequency. In this case, even when the acceleration oscillating at a frequency of 1 Hz or less is detected, the output of the piezoelectric acceleration sensor has an offset reference voltage generation circuit because the resistance value of the ultra-high resistance body is larger than the impedance of the piezoelectric acceleration sensor. It can be prevented from flowing to the side. Therefore, it is possible to obtain an acceleration detection device including a piezoelectric acceleration sensor that can accurately detect acceleration oscillating at a frequency of 1 Hz or less.

However, even if the above configuration is adopted, if the vibration or acceleration becomes 0.1 Hz or less, the output of the amplifier circuit becomes unstable or unstable, and the detection accuracy of the acceleration deteriorates, or the measurement of the acceleration becomes difficult. It turned out to be impossible. As a result of research, it has been found that when the vibration or acceleration becomes 0.1 Hz or less, the cause is that the output voltage of the acceleration sensor becomes too small (or the output current becomes too small). Therefore, in the present invention, the piezoelectric ceramic substrate has one or more detection electrodes on the front surface and one or more counter electrodes facing the detection electrode on the rear surface, and the piezoelectric ceramic substrate is bent by the action of acceleration. In this case, a piezoelectric acceleration sensor that generates spontaneous polarization charge on the detection electrode, an offset reference voltage generation circuit that generates an offset reference voltage that is a reference for the offset voltage, and an output and offset of the detection electrode of the piezoelectric acceleration sensor A voltage amplifying circuit that receives a voltage to a signal input terminal, amplifies an output of the piezoelectric acceleration sensor around an offset voltage, and outputs the amplified voltage as a voltage signal. The following configuration has been adopted as the target of.

First, in the present invention, an ultra-high resistance circuit is electrically connected in parallel between the signal input terminal of the voltage amplifier circuit and the ground. The resistance value of the ultra-high resistance circuit is calculated by calculating the current obtained by converting the current output from the piezoelectric acceleration sensor into a voltage when the piezoelectric acceleration sensor detects acceleration oscillating at a frequency of 0.1 Hz or less. The value is set to a value that can constitute the voltage conversion circuit. When the frequency is high, such an ultra-high resistance circuit has no effect on the operation of amplifying the output voltage of the piezoelectric acceleration sensor. Therefore, when the frequency is high, the same operation as in the related art is performed. When the piezoelectric acceleration sensor detects acceleration oscillating at a frequency of 0.1 Hz or less, the output voltage and output current of the piezoelectric acceleration sensor become extremely small, and the voltage cannot be amplified as it is. Incidentally, the output current of the piezoelectric acceleration sensor in such a state is a minute current on the order of pico or femto-ampere. In such a state, the ultra-high resistance circuit connected in parallel between the signal input terminal of the voltage amplifier circuit and the ground functions as a current-voltage conversion circuit that converts this minute current into a voltage. , The voltage input to the signal input terminal of the voltage amplifier circuit is increased. By the way, the resistance value of this ultra high resistance circuit is 10G
If the input impedance of the voltage amplifier circuit is 1000 times or more the resistance value of the ultra-high resistance circuit, it is possible to detect vibrations or accelerations of ultra-low frequency of 0.1 Hz to 0.001 Hz. It is. If the ultra-high-resistance circuit is constituted by a chip-like ultra-high-resistance body, not only the number of components is reduced but also the circuit configuration is simplified.

The technical idea of the present invention is that the output of the piezoelectric acceleration sensor is not amplified based on the offset voltage,
Naturally, the present invention can be applied to a case where the output of the acceleration sensor is output as it is.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a main configuration of one embodiment of an acceleration detection device including a piezoelectric acceleration sensor according to the present invention. In FIG. 1, a piezoelectric acceleration sensor 4 is provided with detection electrodes for detecting accelerations in the X-axis, Y-axis, and Z-axis directions on the surface of a piezoelectric ceramic substrate, and a counter electrode on the back surface. This is a triaxial type that detects the magnitude and direction of acceleration according to spontaneous polarization charges generated in each detection electrode when the piezoelectric ceramic substrate is bent by the action of acceleration. In FIG. 1, only the circuit for the uniaxial detection electrode is shown, and the circuits for the remaining two-axis detection electrodes are omitted.

In this acceleration detecting device, a power supply voltage Vcc is applied to each unit from a DC power supply such as a battery. FIG.
, 1 is a low impedance reference constant voltage circuit comprising resistors R1 and R2 and an operational amplifier OP1 forming a buffer circuit, and 2 is a voltage amplifier circuit (differential amplifier circuit) comprising resistors R3 and R4 and an operational amplifier OP2. )
It is. Further, reference numeral 3 denotes an offset reference voltage generation circuit which is composed of resistors R5 and R6 and generates an offset reference voltage serving as a reference of the offset voltage. Reference numeral 4 denotes a piezoelectric acceleration sensor. R7 is an ultra-high resistance element connected between the output point of the offset reference voltage generating circuit 3 and the signal input terminal (non-inverting input terminal) of the voltage amplifier circuit 2. R8 is a chip-shaped ultra-high resistance element constituting an ultra-high resistance circuit electrically connected in parallel between the signal input terminal of the voltage amplifier circuit 2 and the ground.

The piezoelectric acceleration sensor 4 has one or more detection electrodes 4b on the front surface of a piezoelectric ceramic substrate 4a and one or more counter electrodes 4c on the back surface facing the detection electrodes 4b. . In the piezoelectric acceleration sensor 4, when the piezoelectric ceramic substrate 4a bends due to the action of acceleration, spontaneous polarization charges are generated on the detection electrodes 4b, and this is output as a current value. The output of the detection electrode 4b of the piezoelectric acceleration sensor 4 is input to a non-inverting input terminal (signal input terminal) of the voltage amplification circuit 2. And the voltage amplification circuit 2
The output point of the offset reference voltage generating circuit 3 (the resistors R5 and R5
The output of the piezoelectric acceleration sensor 4 is amplified around an offset voltage (for example, 1.1 V) determined based on an offset reference voltage appearing at the connection point 6 and output as a voltage signal (acceleration detection signal). The amplification degree of the voltage amplification circuit 2 is
It is determined by the ratio of the first and second gain setting resistors R3 and R4.

In this example, the output point of the offset reference voltage generation circuit 3 and the non-inverting input terminal (signal input terminal) of the voltage amplification circuit 2 or the detection electrode 4b of the piezoelectric acceleration sensor 4
A resistor R7 made of a 2GΩ super high resistance body is disposed between the resistor R7 and the resistor R7. Specifically, as the resistor R7, 2.0 mm × 1.25 m manufactured and sold by Hokuriku Electric Industry Co., Ltd.
An ultra high resistance chip resistor of 2 GΩ with a dimension of m can be used. Note that the resistance value of the resistor R7 is the value of the piezoelectric acceleration sensor 4 when the piezoelectric acceleration sensor 4 detects acceleration oscillating at a frequency of 1 Hz or less (ultra low frequency).
Impedance (for example, about 1.6 GΩ at 0.1 Hz)
Should be larger than Since the resistance value of the resistor R7 is sufficiently larger than the impedance of the piezoelectric acceleration sensor 4 at an extremely low frequency, there is no problem even if the resistance values of the resistors R5 and R6 constituting the offset reference voltage generating circuit 3 are low. Therefore, when the offset reference voltage is adjusted, the selection or adjustment of the resistance value (for example, adjustment by trimming of a trimmable chip resistor) is easy, and the offset reference voltage generation circuit 3 can be configured at low cost. The magnitude of the offset reference voltage is determined in consideration of the sensitivity of the piezoelectric acceleration sensor 1 and the expected maximum peak value of the acceleration to be measured.

The resistor R8 is formed of a 10 GΩ super high resistor. Specifically, as the resistor R8,
2.0mm × 1 manufactured and sold by Hokuriku Electric Industry Co., Ltd.
An ultra high resistance chip resistor of 10 GΩ with a size of 25 mm can be used. The operational amplifier OP2 is a MOS operational amplifier having a very high input impedance using a MOSFET in the first stage input section. The input impedance of the operational amplifier OP2 is desirably 1000 times or more the resistance value of the resistor R8, and has a value of 1 × 10 ¹⁵ Ω or more.

In this embodiment, even when detecting an acceleration oscillating at a frequency of 0.1 Hz or less, the resistance value of the resistor R7 made of an ultra-high-resistance element is larger than the impedance of the piezoelectric acceleration sensor 4; It is possible to prevent the output of the acceleration sensor 4 from flowing into the offset reference voltage generating circuit 3. Also, since a resistor R7 made of an ultra-high resistance element is used without using a complicated impedance adjustment circuit such as a bootstrap circuit including a capacitor, oscillation at an ultra-low frequency of 0.1 Hz or less with a small number of parts. Acceleration can be accurately detected. Moreover,
When detecting acceleration oscillating at a frequency of 0.1 Hz or less, the resistor R8 serves as a current-voltage conversion circuit, converts a minute current output from the acceleration sensor 4 into a voltage, and supplies the voltage to the voltage amplification circuit 2. Therefore, the acceleration that vibrates at a frequency of 0.1 Hz or less can be accurately measured. The chip-shaped ultra-high-resistance body having the largest resistance value currently available is manufactured and sold by Nippon Hydrazine Co., Ltd.
There is an ultra-high resistance body of 00 GΩ. When an ultra-high-resistance element of 100 GΩ is used as the resistor R8, 0.001 Hz
It has been found that acceleration oscillating at a frequency of can also be measured. It will be apparent to those skilled in the art that if an ultra-high resistance body having a larger resistance value is developed in the future, the detectable frequency will be further reduced.

In the above example, a differential amplifier using an operational amplifier OP2 is used as the voltage amplifier circuit 2. However, as shown in FIG. 2, an inverter IV as an inverting amplifier having a very large amplification degree is connected to a voltage amplifier circuit (linear amplifier). ) 2 ′. Even when the inverter IV is used, the detection electrode 4b of the piezoelectric acceleration sensor 4 is connected to the signal input terminal of the inverter IV, and is connected between the output point of the offset reference voltage generation circuit 3 and the signal input terminal of the inverter IV.
There is no change in that a resistor R7 made of a super-high-resistance element of GΩ is arranged, and a resistor R8 made of a super-high-resistance element of 10GΩ is arranged between the signal input terminal of the inverter IV and the ground. According to this example, the number of components is reduced, so that the size can be reduced when the acceleration detection device is modularized. Also in this example, as in the example of FIG. 1, the resistance value of the resistor R7 is sufficiently larger than the impedance of the piezoelectric acceleration sensor 4 at a very low frequency, so that the resistors R5 and R6 constituting the offset reference voltage generating circuit 3 are used. Has no problem even if the resistance value is low, and the offset reference voltage generating circuit 3 can be configured at low cost. When detecting an acceleration that vibrates at a frequency of 0.1 Hz or less, the resistor R8 serves as a current-voltage conversion circuit, converts a minute current output from the acceleration sensor 4 into a voltage, and converts the voltage into a voltage amplification circuit 2 '. To supply
Acceleration that vibrates at a frequency of 0.1 Hz or less can be accurately measured.

In order to reduce the power consumption of the inverter IV, as shown in FIG. 3, resistors R8 and R9
May be externally connected. By the way, Toshiba Corporation is TC7
When an inverter sold under the product number of SLU04FU is used, if the resistance value of the resistors R9 and R10 connected to the outside is 3.3 MΩ, the average current consumption of the circuit can be 1 μA or less. Therefore, it is sufficiently possible to use this kind of acceleration detecting device for a gas meter using a dry battery as a power source.

FIG. 4 is a circuit diagram showing an example of another embodiment of the present invention. The difference from the example of FIG. 1 is that the output point of the offset reference voltage generation circuit 3 ′ is connected to the non-inverting input terminal (signal input terminal) of the voltage amplification circuit 4 and the offset reference voltage generation circuit 3 ′ The point that the piezoelectric acceleration sensor 4 is configured by a voltage dividing circuit composed of two super-high resistance elements R'5 and R'6 and the resistance value of the two super-high resistance bodies R'5 and R'6 is determined. When the impedance of the piezoelectric acceleration sensor 4 is higher than the impedance of the piezoelectric acceleration sensor 4 when detecting the acceleration oscillating at a frequency of 1 Hz or less, and when the piezoelectric acceleration sensor 4 detects the acceleration oscillating at the frequency of 0.1 Hz or less. The point is that the value is determined so that the super high resistance element R'6 can form a current-voltage conversion circuit that converts the current output from the piezoelectric acceleration sensor 4 into a voltage. The other points are substantially the same as those in the example of FIG. In this example, specifically, two ultra-high resistance elements R'5
And R'6 have a resistance value of 10 GΩ or more. Even in such a configuration, as in the examples of FIGS.
Acceleration oscillating at the following frequencies can be accurately detected. In this example, since the offset reference voltage generation circuit 3 'is configured by two ultra-high resistance elements R'5 and R'6, it is easier to adjust the offset reference voltage than in the example of FIG. It is not, however, a practical problem.

The effects obtained in each of the above examples are listed below.

The impedance between terminals of the acceleration sensor is stabilized with the upper limit of the resistance value of the super high resistance element R8.

In the example of FIG. 1 and FIG.
, The non-inverting input terminal of the operational amplifier OP2 is connected to the ground or the ground, so that the terminal voltage becomes the ground or the ground level. Therefore, a general IC amplifier can be used without any problem.

When the frequency is high, the voltage is basically input and the ultra-high resistance R8 functions to ensure the ground level or the ground level. Not flowing. Therefore, even if the resistance value varies, the measurement of the acceleration is hardly affected.

The offset voltage is stabilized.

When detecting vibration and acceleration at a very low frequency, even if disturbance noise is mixed in, it is subjected to I / V conversion by the ultra-high resistance element R8. Is excellent.

The sensitivity is almost constant up to the very low frequency level (DC level).

Even if the resistance value of the ultra-high resistance element R8 changes with time, the resistance value is large, so that the resistance is hardly affected.

Even if a lightning surge enters the acceleration sensor device, it functions as a protection circuit because the ultra-high resistance element R8 performs I / V conversion.

Because of these effects, the spontaneous polarization charge of the piezoelectric acceleration sensor, which cannot be measured without using a circuit technique such as chopping, can be efficiently measured using an inexpensive IC amplifier. . Voltage amplification circuit 2
, A similar function can be achieved by arranging and connecting a pair of transistors such as NMOS differentially at the preceding stage. Further, in the examples shown in FIGS. 1 and 4, the signal processing is simple because a non-inverting amplifier is used, and a practical signal level can be sufficiently obtained by processing such as the amplification factor to compensate for the fixed difference of the sensor. Is also significantly improved.

[0030]

According to the present invention, there is an advantage that acceleration which vibrates at a frequency of 0.1 Hz or less can be detected.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main configuration of one embodiment of an acceleration detection device including a piezoelectric acceleration sensor according to the present invention.

FIG. 2 is a circuit diagram showing a main configuration of another embodiment of the acceleration detecting device including the piezoelectric acceleration sensor according to the present invention.

FIG. 3 is a circuit diagram showing a main configuration of another embodiment of the acceleration detection device including the piezoelectric acceleration sensor according to the present invention.

FIG. 4 is a circuit diagram showing a main configuration of another embodiment of the acceleration detecting device including the piezoelectric acceleration sensor according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reference constant voltage circuit 2 voltage amplification circuit 3 offset reference voltage generation circuit 4 piezoelectric acceleration sensor R7 resistor (ultra high resistance) R8 resistor (ultra high resistance) R'5, R'6 ultra high resistance

Claims (7)

[Claims] A piezoelectric ceramic substrate having at least one detection electrode on a front surface thereof and at least one counter electrode facing the detection electrode on a back surface, wherein the piezoelectric ceramic substrate is actuated by acceleration. A piezoelectric acceleration sensor that generates a spontaneous polarization charge on the detection electrode when flexed; an offset reference voltage generation circuit that generates an offset reference voltage that is a reference for an offset voltage; A piezoelectric acceleration sensor comprising: a voltage amplification circuit that receives an output of an electrode and the offset voltage at a signal input terminal, amplifies an output of the piezoelectric acceleration sensor around the offset voltage, and outputs a voltage signal. An acceleration detection device comprising: an ultra-high resistance circuit electrically connected in parallel between the signal input terminal of the voltage amplification circuit and ground. Converting the current output from the piezoelectric acceleration sensor into a voltage when the piezoelectric acceleration sensor detects an acceleration oscillating at a frequency of 0.1 Hz or less by using the resistance value of the ultra-high resistance circuit. An acceleration detection device including a piezoelectric acceleration sensor, wherein the acceleration detection device is set to a value that can constitute a current-voltage conversion circuit. 2. The piezoelectric type according to claim 1, wherein the ultra-high resistance circuit is formed of a chip-shaped ultra-high resistance body, and the ultra-high resistance body has a resistance value of 10 GΩ or more. An acceleration detection device including an acceleration sensor. 3. The resistance value of the ultra-high resistance body is 10 GΩ to 1
2. The acceleration detection device according to claim 1, wherein the input impedance of the voltage amplification circuit is at least 1000 times the resistance value of the ultra-high resistance element. apparatus. 4. A piezoelectric ceramic substrate having one or more detection electrodes on the front surface and one or more counter electrodes facing the detection electrode on the back surface, wherein the piezoelectric ceramic substrate is actuated by acceleration. A piezoelectric acceleration sensor that generates a spontaneous polarization charge on the detection electrode when bent, an offset reference voltage generation circuit that generates an offset reference voltage that is a reference for the offset voltage, and the detection of the piezoelectric acceleration sensor The output of the first electrode and the offset voltage are input to a non-inverting input terminal, a first resistor is connected between the inverting input terminal and the ground, and a second resistor is connected between the inverting input terminal and the output terminal. A differential amplifier connected to a resistor and applied to the non-inverting input terminal to amplify the output of the piezoelectric acceleration sensor around the offset voltage and output the amplified voltage as a voltage signal. And a piezoelectric acceleration sensor having a circuit, wherein the piezoelectric acceleration sensor has a frequency of 0.1 Hz or less between the signal input terminal of the differential amplifier circuit and ground. A current for converting a current output from the piezoelectric acceleration sensor into a voltage when detecting a vibrating acceleration;
An acceleration detection device including a piezoelectric acceleration sensor, wherein an ultra-high resistance element having an extremely high resistance value that can constitute a voltage conversion circuit is electrically connected in parallel. 5. A piezoelectric ceramic substrate having one or more detection electrodes on a front surface thereof and one or more counter electrodes facing the detection electrodes on a rear surface thereof, wherein the piezoelectric ceramic substrate is actuated by acceleration. A piezoelectric acceleration sensor that generates a spontaneous polarization charge on the detection electrode when flexed; an offset reference voltage generation circuit that generates an offset reference voltage that is a reference for an offset voltage; A piezoelectric amplifier comprising: a voltage amplification circuit that receives the output of the electrode and the offset voltage at a signal input terminal, amplifies the output of the piezoelectric acceleration sensor around the offset voltage, and outputs the amplified voltage as a voltage signal. An acceleration detection device including a sensor, wherein an output point of the offset reference voltage generation circuit is connected to the signal input terminal of the voltage amplification circuit. The offset reference voltage generating circuit is constituted by a voltage dividing circuit composed of two ultra-high resistance elements, and the resistance values of the two ultra-high resistance elements are oscillated by the piezoelectric acceleration sensor at a frequency of 0.1 Hz or less. A piezoelectric-acceleration sensor characterized in that the current-voltage conversion circuit converts a current output from the piezoelectric-type acceleration sensor into a voltage when the acceleration is detected. Acceleration detector. 6. The resistance value of the two ultra-high resistance bodies is 10 G
An acceleration detection device provided with the piezoelectric acceleration sensor according to claim 5, which is equal to or larger than Ω. 7. A piezoelectric ceramic substrate having one or more detection electrodes on a front surface thereof and one or more counter electrodes facing the detection electrodes on a rear surface thereof. A piezoelectric acceleration sensor in which spontaneous polarization charges are generated in the detection electrode when bent, an output of the detection electrode of the piezoelectric acceleration sensor being input to a signal input terminal, and an output of the piezoelectric acceleration sensor And a voltage amplification circuit that amplifies the voltage and outputs a voltage signal as a voltage signal.The acceleration detection device includes a piezoelectric acceleration sensor, wherein an ultra-high resistance circuit is provided between the signal input terminal of the voltage amplification circuit and ground. The piezoelectric acceleration sensor is electrically connected in parallel, and detects the resistance value of the ultra-high resistance circuit and the piezoelectric acceleration sensor when the piezoelectric acceleration sensor detects acceleration oscillating at a frequency of 0.1 Hz or less. An acceleration detection device comprising a piezoelectric acceleration sensor, wherein the acceleration detection device is set to a value that can constitute a current-voltage conversion circuit that converts a current output from the sensor into a voltage.