JPH0980072A - Accelerometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accelerometer for detecting the acceleration accurately at all times in which the scale factor is insusceptible to temperature variation. SOLUTION: A temperature resistive element 120 is mounted on a base 10 constituting a torquer and the temperature variation thereof is detected as resistance variation of temperature resistive element 120. An operational amplifier circuit comprising the temperature resistive element 120 and an additional resistor receives the currents being fed to torquer coils 34A, 34B and outputs a voltage signal indicative of detected acceleration. Resistance of the additional resistor is set as follows; b=[(R10 +R2 )/R2 ]a, where (b) is the temperature coefficient of temperature resistive element 120, R10 is resistance of temperature resistive element 120 under normal temperature, R2 is resistance of the additional resistor, and (a) is the temperature coefficient of torquer constant of torquer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accelerometer, particularly a servo type accelerometer.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show examples of conventional accelerometers. The accelerometer has a first base or frame 10 and a second base or frame 12, and the engaging portion 10e of the first frame 10 and the engaging portion 12e of the second frame 12 are mutually Engagement, whereby the two frames 10, 12 are connected.

The accelerometer is further provided with a flexible joint 20 attached to the mounting portion 10a of the first frame 10 via a pressing plate 18 by a suitable fastener such as a screw.
A rod-shaped pendulum 30 attached to the other end of the flexible joint 20, and a cylindrical pendulum 1 attached to the pendulum 30.
A pair of Toruca coils 34A and 34B and each of the frames 10 and 12 separated from the Toruca coils 34A and 34B.
A pair of disk-shaped permanent magnets 36A, 36B and a pair of cylindrical pole pieces 38A, 38B mounted on the pendulum 30, and a light emitting element 40A spaced from the pole piece 38A, 38B at the tip of the pendulum 30.
And a displacement detection device including the light receiving element 40B.

A pair of stoppers 42A and 42B are arranged at the tip of the pendulum 30 and are spaced therefrom, and the amplitude of the pendulum 30 is limited by the stoppers 42A and 42B. The male threads formed on the outer surfaces of the stoppers 42A and 42B are configured to engage with the female threads formed on the first and second frames 10 and 12, and the stopper 4 is rotated by rotating the stoppers 42A and 42B.
2A, 42B move in their axial direction, which allows the amplitude of the pendulum 30 to be adjusted.

The flange portion 10b of the first frame 10 is provided with a reference surface 10c, and a hole 10d is formed as shown in FIG. By mounting such a reference surface 10c on the corresponding reference surface of the object to be measured and inserting an appropriate fastener such as a screw into the hole 10d, the accelerometer is mounted and fixed to the object to be measured.

A cylindrical terminal case 44 is mounted on the flange portion 10b of the first frame 10, external terminals 50A and 50B are attached to the terminal case 44, and an opening 44a formed in the terminal case 44. Is configured to be closed by a lid 54. The stopper 42
The screw holes in which A and 42B are arranged are also sealed from the outside by an adhesive or the like.

Thus, the inside of the accelerometer has a closed structure. Therefore, after the internal components are assembled, electrical connection is made through the opening 44a, and the inside is evacuated or inert gas is supplied. Filling and closing such an opening 44a with the lid 54, the quality of the components can be maintained for a long time and the life of the accelerometer can be extended.

The pendulum 30, the Toluca coils 34A and 34B attached to the pendulum 30, and the flexible joint 20 are cantilevered by the mounting portion 10a of the first frame 10, and the flexible joint 20 has an appropriate flexible portion 20a. Is formed, whereby the pendulum 30 can swing about the rotation axis O-O passing through the bending portion 20a. The flexible portion 20a may be configured, for example, as shown in FIG. 4, to form a rectangular hole 20e in the flexible joint 20 and to form a thin wall portion in the two column portions on both sides thereof.

The first frame 10 is made of electromagnetic soft iron,
It functions as a yoke (return path) to form a magnetic circuit from the first pole piece 38A to the first frame 10 via the first permanent magnet 36A, and these cooperate with the first torquer coil 34A to form a first circuit. Provide 1 Toruca. The second frame 12 is made of electromagnetic soft iron and functions as a yoke (return path) to form a magnetic circuit from the second pole piece 38B to the second frame 12 via the second permanent magnet 36B. Cooperates with the second Toruca coil 34B to provide a second Toruca.

Here, as shown in the figure, the direction along the central axis of the pendulum 30 in a stationary state is defined as the Z axis, and the direction perpendicular to the Z axis, that is, the direction along the central axis XX of the accelerometer. The X axis is defined as a direction orthogonal to both the X axis and the Z axis.

The cylindrical Toruca coils 34A and 34B are mounted on the pendulum 30 so that the central axes thereof are aligned with the central axis XX of the accelerometer, and the cylindrical pole piece 38.
A and 38B are arranged inside.

The principle of detecting the input acceleration α by the accelerometer of this example will be described with reference to FIGS. 5 and 6. FIG.
Shows an example of the operational amplifier circuit. The operational amplifier circuit is the light receiving element 4.
The amplifier 110 for inputting and amplifying the output current i _{PU of} 0B, the Toruca coils 34A, 34B, and the Toruca coils 34A, 3
4B and a read resistor 111 connected to 4B. An output voltage signal V _{0 of the} accelerometer is obtained from the connection point 112 between the Toruca coils 34A and 34B and the reading resistor 111.

FIG. 6 is a block diagram showing the flow of acceleration detection in the accelerometer. Description will be given along blocks 101 to 108. In blocks 103 and 105, S represents a Laplace operator.

At block 101, when the input acceleration α acts along the central axis line XX of the accelerometer, the acceleration α acts on the pendulum 30. Let P be the pendulum of the pendulum 30. Next, in blocks 102 and 103, the pendulum 30 rotates about the rotation axis O-O passing through the bending portion 20a, and its tip portion is slightly displaced.

As shown in block 103, such a small amount of displacement is obtained by the inertia moment I of the pendulum 30 and the bending portion 20a.
Is determined by the spring constant k of

At block 104, the displacement of the tip of the pendulum 30 is detected by a displacement detector. When the tip of the pendulum 30 is displaced, the amount of light emitted by the light emitting element 40A and received by the light receiving element 40B changes,
The output current of the light receiving element 40B changes. Block 104
At, K _PU is the gain of the displacement detection device.

Thus, the output current from the light receiving element 40B of the displacement detecting device represents a minute displacement. Blocks 105 and 10
At 6, the output current i _PU of the light receiving element 40B is processed by the operational amplifier circuit to obtain the torquer drive current i. The Toruca driving current i is fed back to the Toruca coils 34A and 34B in block 108. At block 108, K _T is the Toluca constant for Toluca.

When the current flowing through the Toruca coils 34A and 34B changes, the pendulum 3 is generated due to the magnetic flux density passing through the Toruca coils 34A and 34B and the pole pieces 38A and 38B.
0 is slightly displaced around the rotation axis O-O passing through the bending portion 20a. In the adder 102, the small displacement due to the current i flowing through the torquer coils 34A and 34B is subtracted from the small displacement due to the input acceleration α. ToruCa coil 34
The ToruCa drive current i supplied to A and 34B is the pendulum 3
Since it is proportional to a small displacement of 0, the displacement of the tip of the pendulum 30 becomes zero.

When the displacement of the tip of the pendulum 30 becomes zero, the input acceleration α can be measured by detecting the current i flowing in the torquer coils 34A and 34B. At block 107, the Toruca coils 34A, 34B
The current i flowing through is converted into a voltage signal V ₀ . The input angular velocity α is obtained from the voltage signal V ₀ thus obtained.

Hereinafter, the output voltage signal V from the operational amplifier circuit will be described.
The relationship between ₀ and the input angular velocity α is shown by an equation. In the block diagram of FIG.

[0021]

[Formula 1] K _PU · K _A · K _T / (R _L + R _S ) = K K / (K + k) = K ₁ 1 / (K + k) = K ₂

If we solve for the current i,

[0023]

[Equation 2] i = K ₁ · (IK ₂ S ² + T _D K ₁ S + 1) ⁻¹
・ (P / K _T ) α

It becomes Here, K such that K >> k
If you select the values of _PU , K _A , K _T , R _L , and R _S ,

[0025]

## EQU3 ## i = [(I / K) S ² + T _D S + 1] ^-1 · (P
/ K _T ) α

Since the voltage signal V ₀ is the product of the Toruca current i and the read resistance R _S , V ₀ = iR _S.

[0027]

[Formula 4] V ₀ = [(I / K) S ² + T _D S + 1] ⁻¹ ·
(PR _S / K _T ) α

In the low frequency region, this equation is more simply expressed as follows.

[0029]

(5) V ₀ = (PR _S / K _T ) α

Here, P is the pendulum of the pendulum 30, R _S is the resistance value of the reading resistor, K _T is the Toruca constant, and α is the input acceleration.

The Toruca constant K _{T in} the equation (5) is defined by the permanent magnets 36A and 36B and the Toruca coil 34A which form the Toruca.
34B. However, the permanent magnets 36A, 36
The magnetomotive force of B fluctuates due to changes in ambient temperature. Therefore, the Toruca constant K _T generally changes depending on the temperature of the Toruca and is expressed as follows.

[0032]

[Equation 6] K _T = K _T0 (1 + aΔT)

Where K _T0 is the Toruca constant at room temperature,
a is the temperature coefficient of the Toruca constant, and ΔT is the temperature deviation from room temperature. The temperature coefficient a of the Toruca constant K _T is generally a <
0. The expression of Expression 6 is substituted into the expression of Expression 5. Since the temperature coefficient a of the Toruca constant K _T is minute, the following approximate expression can be obtained.

[0034]

## EQU7 ## V ₀ = (PR _S / K _T ) α = PR _S α / [K _T0 (1 + aΔT)] ≈PR _S α (1-aΔT) / K _T0

Here, the output voltage V with respect to the input acceleration α
The ratio of ₀ is referred to as the accelerometer scale factor F _S. Therefore, it is expressed as follows.

[0036]

## EQU8 ## PR _S (1-aΔT) / K _T0 = F _S V ₀ = F _S α

The scale factor F _S of the accelerometer is a function of temperature as expressed by the equation (8) and changes with temperature. Therefore, when the temperature changes, an error occurs in the output voltage V ₀ of the accelerometer.

A second conventional example of the accelerometer will be described with reference to FIG. FIG. 7 shows details of a portion of the first Toruca of the second conventional example. The second torquer has the same structure as the first torquer, and the parts other than the first and second torquers are the same as the first conventional example of the accelerometer described with reference to FIGS. 3 and 4. Have a configuration. Details of the accelerometer shown in FIG. 7 are described in Japanese Patent Application No. 1-1355 by the same applicant as the present applicant.
See No. 24.

The second conventional example is constructed so that the scale factor F _S of the accelerometer is always constant regardless of the temperature. In this example, the gap G in the circumferential direction between the pole piece 38A and the first frame 10 (pot-shaped yoke).
The magnetic flux Φ _G passing through is always constant without being affected by changes in ambient temperature.

As shown in the drawing, a spool member 60A made of magnetic shunt alloy having a circular cross section is provided along the central axis of the first torquer. That is, the first frame 10 and the permanent magnet 3
6A and the pole piece 38A are provided with through holes, and the spool member 60A is inserted into the through holes.

The spool member 60A includes a magnetic flux compensating portion 60b having a small central diameter and magnetic flux introducing portions 60 having large diameters on both sides thereof.
a and 60c, the inner magnetic flux introducing portion 60a is arranged in the pole piece 38A, the intermediate magnetic flux compensating portion 60b is arranged in the permanent magnet 36A, and the outer magnetic flux introducing portion 60c.
Are arranged in the first frame 10 (pot-shaped yoke).

As indicated by the arrow in FIG. 7, the magnetic flux Φ _M passing through the permanent magnet 36A is the magnetic flux Φ _G passing through the first frame 10 (pot-shaped yoke) and the magnetic flux Φ passing through the spool member 60A.
It is divided into _S and. If the ratio of the diameter of the magnetic flux compensating portion 60b and the diameter of the magnetic flux introducing portions 60a and 60c is set to a predetermined value, the gap G
The magnetic flux Φ _G passing through is always constant.

Thus, the spool member 6 is attached to the first torquer.
0A is arranged, and the magnetic flux compensating section 60b and the magnetic flux introducing section 60a,
By setting the ratio of the cross-sectional area of 60c to an appropriate value, the magnetic flux Φ _G passing through the gap G from the pole piece 38A and passing through the first frame 10 (pot-shaped yoke) becomes constant,
Scale factor errors due to temperature variations are eliminated.

[0044]

In the conventional accelerometer shown in FIG. 7, spool members 60A and 60B are used in order to eliminate the scale factor error due to temperature fluctuations, which complicates the structure and makes the manufacturing process difficult. There was a drawback that it increased.

Further, in such a conventional example, the spool member 6
0A and 60B were fixed to the holes formed in the pole piece 38A and the first frame 10 (pot-shaped yoke) or the second frame 12 (pot-shaped yoke) by press fitting or the like.
That is, the magnetic flux introducing portions 60a inside the spool members 60A and 60B were press-fitted into the holes of the pole piece 38A, and the magnetic flux introducing portions 60c outside were press-fitted into the holes of the first frame 10 or the second frame 12.

Therefore, in the conventional accelerometer, the permanent magnet 36
A, 36B, pole pieces 38A, 38B, frame 1
0, 12 (pot-shaped yoke) and spool members 60A, 60
It was difficult to manufacture and assemble the ToruCa containing B.

In view of the above point, the present invention provides an accelerometer that can always detect an accurate acceleration without changing the scale factor due to a change in ambient temperature and has a simple structure. With the goal.

[0048]

According to the present invention, for example, as shown in FIGS. 1 and 2, a base, a flexible joint mounted on the base, and one end of the flexible joint are attached. A pendulum, a displacement detection device that detects the displacement of the pendulum with respect to the base, a torquer that generates a torque proportional to the displacement detected by the displacement detection device, and a current signal supplied to the torquer. And an operational amplifier circuit for generating a voltage signal by means of a voltage signal output from the operational amplifier circuit. It includes a resistance temperature element having a temperature coefficient b of the same polarity as and having a resistance value linearly changing with temperature.

According to the present invention, in the accelerometer, the temperature coefficient b of the resistance temperature element is equal to the temperature coefficient a of the Toruca constant of the Toruca, and b = a.
Further, the operational amplifier circuit has an additional resistance connected in parallel to the resistance temperature element.

According to the present invention, in the accelerometer, the resistance value R ₂ of the additional resistance is set based on the following equation. b = [(R ₁₀ + R ₂ ) / R ₂ ] a where b is the temperature coefficient of the resistance temperature element, R ₁₀ is the resistance value of the resistance temperature element at room temperature, and a is the temperature coefficient of the Toruca constant of the Toruca. Is.

[0051]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 2, corresponding parts in FIGS. 3 to 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

The accelerometer of this example has a resistance temperature element 120 for compensating the temperature sensitivity of the torquer. The resistance temperature element 120 is an element having temperature sensitivity of the same polarity as the temperature sensitivity of the Toruca constant, and is configured so that the resistance value changes linearly with temperature.

The resistance temperature element 120 is arranged at an appropriate position so as to respond to the temperature of the torquer. For example, holes may be provided in the first or second frames 10 and 12 and the holes may be arranged in the holes. In FIG. 1, it is arranged in a hole provided in the first frame 10.

A printed wiring board or hybrid IC
The resistance temperature element 120 may be arranged above. In such a case, the printed wiring board or the hybrid IC on which the resistance temperature element 120 is mounted is arranged at an appropriate position inside the accelerometer so as to have the same temperature response as that of the torquer.

The accelerometer of this example may have the same structure as that of the conventional accelerometer shown in FIGS. 3 and 4, except for the resistance temperature element 120 and the operational amplifier circuit connected thereto.

An example of an operational amplifier circuit used in the accelerometer according to the present invention will be described with reference to FIG. The operational amplifier circuit of the present example is different from the operational amplifier circuit of the conventional accelerometer of FIG. 5 in that the resistance temperature element 120 is used instead of the reading resistor 111.
And an additional resistor 121 is arranged.

The operational amplifier circuit of this example includes an amplifier 110 for inputting and amplifying the output current i _PU of the light receiving element 40B, a torquer coil 34A, 34B, and a resistance temperature element 120 and an additional resistor 121 connected to the torquer coil 34A, 34B. Have. The additional resistor 121 is connected in parallel to the resistance temperature element 120. The voltage signal V ₀ is obtained from the connection point 112 between the Toruca coils 34A and 34B and the resistance temperature element 120.

In order to explain the basic principle of the present invention, the additional resistor 121 is removed and considered. When the additional resistor 121 is removed, the operational amplifier circuit of this example becomes the same as the operational amplifier circuit of FIG. Therefore, if the resistance value R ₁ of the resistance temperature element 120 is used instead of the read resistance R _S , the formula 1 to formula 8
The argument of the formula of is established.

The output voltage V ₀ of the accelerometer is the product of the Toruca current i and the resistance value R ₁ of the resistance temperature element 120. Therefore, it is expressed as follows.

[0060]

[Formula 9] V ₀ = i · R ₁

[0061] In Equation 7 wherein the, R ₁ far as the expression instead structured R _S is obtained.

[0062]

## EQU10 ## V ₀ = PR ₁ α (1-aΔT) / K _T0

Here, P is the pendulum of the pendulum 30, α is the input acceleration, K _T0 is the Toruca constant at room temperature,
a (<0) is the temperature coefficient of the Toruca constant K _T , and ΔT is the temperature deviation from room temperature.

It is assumed that the temperature characteristic of the resistance R ₁ of the resistance temperature element 120 is expressed by the following equation.

[0065]

[Formula 11] R ₁ = R ₁₀ (1 + bΔT)

Here, R ₁₀ is the resistance value of the resistance temperature element 120 at room temperature, b is the temperature coefficient of the resistance value of the resistance temperature element 120, and ΔT is the temperature deviation from room temperature.

This equation is substituted into the equation (10) to transform it.

[0068]

## EQU12 ## V ₀ = PR ₁₀ α (1-aΔT) (1 + bΔT) / K _T0 ≈PR ₁₀ α [1+ (b-a) ΔT] / K _T0

Therefore, if b = a, V ₀ = PR ₁₀ α / K
_T0, and the output voltage V ₀ which the accelerometer is constant regardless of the temperature. In general, the temperature sensitivity of the Toruca can be compensated by using the resistance temperature element 120 having the temperature coefficient a having the same absolute value and the same polarity as the temperature coefficient a of the Toruca constant K _T.

However, in general, the resistance temperature element 12 having a temperature coefficient b equal to the temperature coefficient a of the Toruca constant K _T.
It is difficult to obtain 0. Therefore, in this example, FIG.
As shown in FIG.
21 is connected. As a result, as will be described below, even the resistance temperature element 120 having the temperature coefficient a that is not equal to the temperature coefficient a of the Toruca constant K _T can compensate the temperature sensitivity of the Toruca.

The output voltage V ₀ of the accelerometer in the operational amplifier circuit shown in FIG. 2 is expressed as follows.

[0072]

[Formula 13] V ₀ = i · R ₁ R ₂ / (R ₁ + R ₂ )

Here, R ₁ is the resistance value of the resistance temperature element 120, and R ₂ is the resistance value of the additional resistor 121. Here, when the current i is set as i = i ₀ (1 + aΔT) and the resistance value R ₁ is represented by the equation (11), the following equation is obtained.

[0074]

## EQU14 ## V ₀ = i ₀ R ₂ R ₁₀ (1 + bΔT) (1-a
ΔT) / [R ₂ + R ₁₀ (1 + bΔT)]

If the right side of this equation is Taylor-expanded by ΔT, it can be approximated as follows. In addition, f = R ₂ / (R
₂ + R ₁₀ ).

[0076]

V ₀ = fi ₀ R ₁₀ [1 + (− a + fb) ΔT]

Therefore, if -a + fb = 0, the output voltage V ₀ of the accelerometer becomes constant regardless of the temperature change. That is,

[0078]

## EQU16 ## a / b = R ₂ / (R ₂ + R ₁₀ )

Thus, according to the present example, the equation 16 is satisfied.
So that the resistance value R of the additional resistor 121 ₂If you set
Yes. That is, a resistance temperature element having an arbitrary temperature coefficient of resistance b
Even with 120, the temperature of the scale factor of the accelerometer
The sensitivity can be zero.

When the expression (16) is satisfied, the output voltage V ₀ of the accelerometer is expressed as follows.

[0081]

V ₀ = (a / b) i ₀ R ₁₀ = i ₀ R ₂ R ₁₀ /
(R ₂ + R ₁₀ )

[0082] According to this embodiment, as the resistance value R ₁ of the resistance temperature element 120 is represented by the numerical formula 11, a resistance value R ₁ by temperature change varies linearly, of such resistor R ₁ The temperature coefficient b is selected so as to satisfy the equation (16). As shown in the equation (16), the temperature resistance element 120
The polarity of the temperature coefficient b of the resistance value R ₁ is the same as the polarity of the temperature coefficient a of the Toruca constant K _T.

Although the embodiments of the present invention have been described in detail above, those skilled in the art will understand that the present invention is not limited to the above-mentioned embodiments and various other configurations can be adopted without departing from the gist of the present invention. Easy to understand.

[0084]

According to the accelerometer of the present invention, by providing the temperature resistance element 120 and making the temperature coefficient b of the temperature resistance element 120 equal to the temperature coefficient a of the Toruca constant K _T , the temperature sensitivity of the Toruca is improved. Because I can compensate
This has the advantage that accurate acceleration can be detected without being affected by temperature changes.

According to the accelerometer of the present invention, the temperature resistance element
The temperature coefficient b of 120 is the Toluca constant K _TTo the temperature coefficient a of
Provide additional resistance to resistance temperature element
To compensate for Toluca's temperature sensitivity
Accurate acceleration without being affected by temperature changes
It has the advantage that the degree can be detected.

The accelerometer of the present invention has the advantage that by providing the resistance temperature element and the additional resistance, the scale factor error due to the temperature change can be removed without changing the mechanical structure.

In the accelerometer of the present invention, even if the temperature sensitivity of the scale factor is different for each accelerometer, the scale factor error can be easily removed by selecting the resistance value of the resistance temperature element and the resistance value of the additional resistance. There is an advantage that can be.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an accelerometer of the present invention.

FIG. 2 is a cross-sectional view showing an example of an operational amplifier circuit of the accelerometer of the present invention.

FIG. 3 is a plan view showing the inside of an example of a conventional accelerometer.

FIG. 4 is a diagram showing a part of a conventional accelerometer.

FIG. 5 is a diagram showing a conventional operational amplifier circuit of an accelerometer.

FIG. 6 is a functional block diagram of a conventional accelerometer.

FIG. 7 is a diagram showing a part of another example of a conventional accelerometer.

[Explanation of symbols]

 10 Base (frame) 10a Attachment part 10b Flange part 10c Reference surface 10d Hole 10e Engagement part 12 Base (frame) 12e Engagement part 18 Holding plate 20 Flexible joint 20a Flexible part 20b Fixed part 20d Mounting part 20e Hole 30 Pendulum 34A, 34B Toruca coil 36A, 36B Permanent magnet 38A, 38B Pole piece 40A Light emitting element 40B Light receiving element 42A, 42B Stopper 44 Terminal case 44a Opening 50A, 50B External terminal 54 Lid 60A, 60B Spool member 60a, 60c Magnetic flux introducing part 60b Magnetic flux Compensator 62A, 62B Nut 110 Amplifier 111 Reading resistance 112 Connection point 120 Resistance temperature element 121 Additional resistance

Claims (4)

[Claims] 1. A base, a flexible joint mounted on the base, a pendulum attached to one end of the flexible joint, and a displacement detector for detecting displacement of the pendulum with respect to the base. A torquer that generates a torque proportional to the displacement detected by the displacement detection device, and an operational amplifier circuit that inputs a current signal supplied to the torquer to generate a voltage signal are provided. In the accelerometer configured to obtain the acceleration from the output voltage signal, the operational amplifier circuit has a temperature coefficient b having the same polarity as the Toruca constant a of the Toruca, and the resistance value linearly changes with temperature. An accelerometer including a resistance temperature element. 2. The accelerometer according to claim 1, wherein the temperature coefficient b of the resistance temperature element is equal to the temperature coefficient a of the Toruca constant of the Toruca, and b = a. 3. The accelerometer according to claim 1, wherein the operational amplifier circuit has an additional resistance connected in parallel with the resistance temperature element. 4. The accelerometer according to claim 3, wherein the resistance value R ₂ of the additional resistance is set based on the following equation. b = [(R ₁₀ + R ₂ ) / R ₂ ] a where b is the temperature coefficient of the resistance temperature element, R ₁₀ is the resistance value of the resistance temperature element at room temperature, and a is the temperature coefficient of the Toruca constant of the Toruca. Is.