JP2000205934A - Weight detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the stability of detecting accuracy by detecting load at a pressure level. SOLUTION: A piezoelechic transformer 14 where a drive 12 is formed by providing input electrodes 12a, 12b longitudinally on the upper and lower surfaces of a piezoelechic ceramic plate 11 at one end face thereof, and where a power generating part 13 is formed by providing an output electrode 13a on the other end face, is provided with a load transmission means 18 which transmits load, with a support means 19 between the transformer 14 and the means 18. A frequency is applied to the drive 12 by a signal generation means 15 and a computing part 16 computes an output signal from the power generating part 13 so as to calculate the load applied, thereby stabilizing output sensitivity and enabling the load applied to be detected easily even if it is at a pressure level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the technology of a weight detecting device.

[0002]

2. Description of the Related Art Conventional weight detection devices of this type include:
There is a bimorph-type weight detecting device as shown in FIG. 11 (for example, IEEE Transaction on Electron Devices,
vol.ED-26, No.5, p815-p817, 1979. This bimorph-type weight detector will be described with reference to FIG.

The electrodes 1b, 1c are provided on both sides of the piezoelectric film 1a.
And a band-shaped piezoelectric film 2 provided with electrodes 2b and 2c on both sides of a piezoelectric film 2a, and one end thereof is supported in a cantilever manner by a support portion 3. . The piezoelectric film 1 has electrodes 1
A voltage is applied from the transmitting unit 4 connected to the electrodes b and 1c to vibrate, and an output signal due to the vibration is extracted from the electrodes 2b and 2c of the piezoelectric film 2. With this configuration, the object 5 can be
When the contact is made, the weight is detected and the output signal from the piezoelectric film 2 changes, thereby detecting the contact with the object.

[0004]

However, with the conventional weight detecting device, it is possible to detect the presence or absence and the contact position of the object 5 on the piezoelectric film 2, but the pressure level due to the contact of the object 5 is reduced. There was a problem that it could not be detected. In addition, since the support portion 3 has a configuration in which one end is supported in a cantilever shape, when the object repeatedly contacts, the piezoelectric films 1 and 2 are deteriorated and the detection sensitivity is reduced. I was

In order to further improve the detection sensitivity and the stability of the output signal, it is necessary to increase the voltage applied from the transmitting section 4 and to add a gift to the circuit side. Had the problem of becoming In addition, when this type of weight detecting device is used for various purposes, it is desired to detect pressure and vibration simultaneously, but there is a problem that such a demand cannot be met.

[0006]

According to the present invention, in order to solve the above-mentioned problems, input electrodes are provided above and below one end face of a piezoelectric ceramic plate to form a drive section, and the other end face is provided with a drive section. A piezoelectric transformer provided with an output electrode to form a power generation unit,
Load transmitting means for transmitting a load applied to the piezoelectric transformer, supporting means provided at a contact portion between the load transmitting means and the piezoelectric transformer, signal generating means for applying a frequency to the driving section, And a calculation unit for calculating the applied load by calculating the output signal of the transformer.

When a load is applied to the piezoelectric transformer vibrating at the frequency applied by the signal generating means and pressure is applied, the vibration characteristics of the piezoelectric transformer change according to the pressure, and the power generation unit Since the piezoelectric electromotive force generated in the power generation unit also changes, the applied load can be easily detected with a simple configuration by calculating the piezoelectric electromotive force taken out from the output power supply formed in the power generation unit by the calculation unit. .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The weight detecting device of the present invention can be embodied with the structure described in each claim.
This will be described together with the operation and effect.

According to the present invention, an input electrode is provided in the longitudinal direction of the upper and lower surfaces on one end face side of the piezoelectric ceramic plate to form a drive section, and an output electrode is formed on the other end face. A piezoelectric transformer provided with a power generating unit, a load transmitting unit for transmitting a load applied to the piezoelectric transformer, a supporting unit provided at a contact portion between the load transmitting unit and the piezoelectric transformer, and a driving unit. A signal generating means for applying a predetermined frequency to vibrate the piezoelectric transformer; and a calculating part for calculating an applied load by calculating an output signal of the piezoelectric electromotive force generated in the power generating part.

[0010] When a load is applied to the piezoelectric transformer vibrating at the frequency applied by the signal generating means, the vibration characteristics of the drive section change according to the pressure based on the load,
Since the piezoelectric electromotive force generated in the power generation unit also changes, it is possible to detect the load easily applied with a simple configuration by calculating the piezoelectric electromotive force extracted from the output electrode provided in the power generation unit by the calculation unit. Can be.

According to a second aspect of the present invention, in the piezoelectric transformer, a drive section is formed by providing input electrodes in the longitudinal direction of the upper and lower surfaces on one end face side of the piezoelectric ceramic plate, and a drive section is formed on the other end face. Is formed with a plurality of output electrodes.

Then, the piezoelectric electromotive force is extracted from each output electrode, and the arithmetic unit can use a plurality of detection signals, so that the load can be detected with high reliability and the output output from each output electrode can be obtained. By determining the magnitude of the signal, the output piezoelectric electromotive force can be selected and output as needed.

According to a third aspect of the present invention, the supporting means is formed by an elastic member.

Since the vibration of the piezoelectric transformer is absorbed and the friction with the supporting means is reduced by using the elastic member as the supporting means, the stability of the detection sensitivity can be improved.

According to a fourth aspect of the present invention, the supporting means is provided near a node of vibration of the piezoelectric transformer.

By providing the support means near the node where the piezoelectric transformer vibrates, the vibration of the piezoelectric transformer is not hindered, so that the stability of the detection sensitivity can be improved.

Further, the elastic member used for the supporting means has a small contact area with the piezoelectric transformer, for example, like a mesh.

Since the resistance between the piezoelectric transformer and the supporting member can be reduced by using the supporting means having a small contact area with the piezoelectric transformer, the stability of the output signal from the piezoelectric transformer can be improved. it can.

According to a sixth aspect of the present invention, the load transmitting means is provided with a fulcrum, a force point, and an action point to reduce the load applied to the piezoelectric transformer.

Since the load is applied to the piezoelectric transformer via the point of action, and the load is not directly applied to the piezoelectric transformer, the load can be reduced and the piezoelectric transformer can be prevented from being damaged. The relationship between the load applied to the piezoelectric transformer and the output signal is such that the lower the load, the greater the change in the output signal, so that the detection sensitivity can be improved.

[0021] Further, as described in claim 7, the point of force provided in the load transmitting means has its position adjustable so that the load applied to the piezoelectric transformer can be varied.

Since the load applied to the piezoelectric transformer can be adjusted by moving the position of the point of force, the output sensitivity can be easily selected as required.

Further, according to the present invention, a lead wire having a diameter of 0.3 mm or more, which is hardly affected by vibration, is used for taking out an input electrode and an output electrode of a piezoelectric transformer.

[0024] The stability of the output signal of the piezoelectric transformer can be improved by making the lead wire hardly affected by the vibration of the piezoelectric transformer itself.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 shows a configuration diagram of a weight detecting apparatus according to Embodiment 1 of the present invention.

Input electrodes 12a and 12b are provided in the longitudinal direction on both front and rear surfaces on one end face side of the piezoelectric ceramic plate 11 (length 50 mm, width 13 mm, thickness 2 mm) to form a drive section 12, and the other end face. An output electrode 13a is provided in the unit to form a power generation unit 13. The driving unit 12 and the power generation unit 13 form a piezoelectric transformer 14. Lead wires 17a, 17b are connected to the input electrodes 12a, 12b of the drive unit 12, respectively.
The signal generator 15 is connected to the drive unit 13 via the. The output electrode 13a provided on the power generation unit 13 is connected to the calculation unit 16 via a lead wire 17c to calculate an applied load. The input electrodes 12a and 12b and the output electrode 13a can be formed by printing silver paste or the like, for example, but may be formed by depositing a metal material such as aluminum.

The driving section 12 is polarized between the input electrode 12a and the input electrode 12b, and the power generating section 13 is polarized between the output electrode 13a and the input electrodes 12a and 12b. Is indicated by an arrow on the piezoelectric ceramic plate 11.

The load applied to the weight detecting device is transmitted to the piezoelectric transformer 14 via the load transmitting means 18.
Support members 19 provided on the upper and lower surfaces to support the
Attached to.

Next, the operation and action will be described.

First, in response to the oscillation signal generated by the signal generation means 15, the input electrodes 12a, 12
The drive unit 12 sandwiched between b. The following description is based on the assumption that the frequency of the oscillation signal generated by the signal generator 15 is f1. The vibrating part propagates to the vibration power generating part 13 of the twelve, and generates a piezoelectric electromotive force, that is, a detection voltage according to the vibration. When a load W is applied to at least one of the drive unit 12 of the piezoelectric transformer 14 or the power generation unit 13 via the load transmitting unit 18 and the support member 19 as shown in FIG. Thus, it can be grasped as the piezoelectric electromotive force V1 generated in the power generation unit 13.

FIG. 2 shows an oscillation signal V0 generated by the signal generating means 15 when a load W is applied to the piezoelectric transformer 14.
(Frequency f1) and the signal waveform of the piezoelectric electromotive force V1 generated in the power generation unit 13 are shown in the characteristic diagram of FIG.
In a state where no object is placed on the, that is, when there is no load W (t <t1), the piezoelectric electromotive force V1 is output in synchronization with the oscillation signal V0. In addition, the drive unit 12 generates the power
, A phase difference L01 occurs due to the propagation of the vibrations.

Next, when a certain object is mounted or a load W is applied due to the atmospheric pressure or the pressure of the liquid, the vibration of the drive unit 12 is hindered by the applied pressure. Decreases from D0 to D1, and the phase also changes from L0 to L01. The value of the applied load W can be calculated by the calculation unit 16 based on the change in the vibration characteristics when the load is applied.

FIG. 3 shows that the driving unit 12 is driven with a constant amplitude, that is, an oscillation signal 10 V from the signal generating unit 15, and is obtained by the power generating unit 13 when a load of 1 kg or 2 kg is applied to the entire surface of the piezoelectric transformer 14. FIG. 4 is a characteristic diagram illustrating a frequency characteristic of a piezoelectric electromotive force D.

Here, a load resistance of 20 kΩ is inserted between the output electrode 13a and the input electrode 12b. Then, the load W, that is, the load 1 kg or 2 kg
In contrast, it can be seen that the piezoelectric electromotive force D obtained by the power generation unit 13 is highest at the resonance frequency and decreases as the frequency deviates from the resonance frequency.

Therefore, the output signal of the signal generating means 15 is
The sensitivity can be improved by setting the piezoelectric transformer 14 near the resonance frequency which is the frequency of the region where the longitudinal vibration mode and the width vibration mode are coupled. Further, as the applied load increases, the vibration of the piezoelectric transformer 14 is suppressed. Therefore, as shown in FIG. 3, when the applied load increases, the piezoelectric electromotive force, which is the output voltage, decreases. Further, as shown in FIG. 4, the relationship between the load 1 kg to 5 kg applied near the first resonance frequency of 32 to 33 kHz of the piezoelectric transformer and the piezoelectric electromotive force D becomes higher. Since the electromotive force D has changed, the calculation unit 16 can calculate the applied load from the output signal of the power generation unit 13.

(Embodiment 2) FIG. 5 shows a configuration diagram of a weight detecting apparatus according to Embodiment 2 of the present invention, which is different from Embodiment 1 in that a plurality of output electrodes are provided.
Note that the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

The drive unit 12 of the piezoelectric transformer 14 is provided with input electrodes 12 a and 12 b on the upper and lower surfaces thereof.
Has a plurality of output electrodes 13a-1a divided in the length direction.
3d is provided. Each output electrode 13a, 13
The width dimensions of b, 13c, and 13d are the same, and the intervals between the output electrodes 13a to 13d are also the same. If the electrode 13b close to the driving unit 12 is on the ground side, the electrode 13c is a first output electrode, the electrode 13d is a second output electrode, and the electrode 13a is a third output electrode, the output electrodes 13c, An output having a magnitude of 1/3 times, 2/3 times, or the like of the reference voltage can be obtained for each of 13d and 13a. Further, by changing the number of output electrodes and the interval between the output electrodes variously, each of the output electrodes 13a to 13d
, The magnitude of the output signal to be output can be obtained arbitrarily, so that the piezoelectric electromotive force to be output can be selected as necessary, and since there are multiple outputs, reliability is increased, and more accurate weight is obtained. Detection becomes possible.

(Embodiment 3) In Embodiment 3, an elastic member is used as the support means 19 in Embodiments 1 and 2. As the elastic member, a flat silicon rubber having a thickness of 5 mm is used, and is provided on the entire upper and lower surfaces of the piezoelectric transformer 14.

As described in the first embodiment, the principle of the weight detecting device is as follows. A predetermined transmission signal is applied to the piezoelectric transformer 14 to vibrate, and the piezoelectric electromotive force generated at that time is taken out as an output signal. When a load is applied to the piezoelectric transformer 14 in the state,
The applied load is calculated by the calculation unit 16 using this relationship because the piezoelectric electromotive force generated by the suppression of the vibration is also reduced. However, since the vibration of the piezoelectric transformer 14 necessarily depends on the supporting means 19, the supporting means 1
9 is made of a hard material, vibration cannot be absorbed.
As a result, it becomes impossible to stably output the piezoelectric electromotive force due to an increase or a change in friction between the piezoelectric electromotive force and the piezoelectric element 9.

The piezoelectric electromotive force (V) output when the silicon rubber (thickness 2 mm) as an elastic body is used and the glass plate (thickness 2 mm) as a hard body is used as the support means 19. Considering the stability, the result is as shown in FIG. The horizontal axis indicates the time during which the signal was applied, and the vertical axis indicates the piezoelectric electromotive force at that time. Also, the piezoelectric transformer 14 has 3
A transmission signal having a first resonance frequency of 2.5 KHz and an amplitude of 10 V was applied.

As a result, when the elastic material was used as the support means 19, the time dependency was low, and the output change rate was 1.2% in about 30 minutes, whereas when the hard material was used. Means that the rate of change in about 30 minutes is about 3.6%,
9 is made of an elastic material, the output stability is about 3
And the accuracy of weight detection can be improved.

(Embodiment 4) FIG. 7 shows a configuration diagram of a weight detecting device according to Embodiment 4 of the present invention. In Embodiment 4, an elastic member is used as the support means 19 in Embodiments 1 to 3, In addition, it is provided near a node of vibration of the piezoelectric transformer 14.

As the elastic member used for the support means 19, a flat silicon rubber having a thickness of 2 mm, a width of 15 mm and a length of 15 mm is used, and is provided in the vicinity of a vibration node of the piezoelectric transformer 14. Here, if the oscillation signal applied from the signal generating means 15 is a signal having a half wavelength and a first resonance frequency, FIG.
As shown in (1), since the node of vibration in the piezoelectric transformer 14 is located at a position corresponding to a half of the entire length of the piezoelectric transformer 14, the support means 19 is provided around this position. When the transmission signal has one wavelength, the nodes of vibration in the piezoelectric transformer 14 are １ ／ and ／ of the total length of the piezoelectric transformer 14.
Position.

With the above configuration, a signal having a first resonance frequency of 32.5 kHz and an amplitude of 10 V was applied to the piezoelectric transformer 14 from the signal transmitting means 15.
The time dependency of the output change rate is about 0.1% in 30 minutes,
As compared with the case where a flat elastic member is provided on the entire surface of the piezoelectric ceramic 14 as the support means 19, the stability can be improved by about 12 times.

(Embodiment 5) FIG. 8 is an exploded view of a weight detecting device according to Embodiment 5 of the present invention. In Embodiment 5, an elastic member used as the support means 19 in Embodiments 1 to 4 is used. It is configured in a mesh shape.

Note that the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.
As the elastic member used for the support means 19, a 2 mm-thick mesh-like silicon rubber is used, and is provided on the entire upper and lower surfaces of the piezoelectric transformer 14.

With the above configuration, an oscillation signal having a first resonance frequency of 32.5 kHz and an amplitude of 10 V was applied to the piezoelectric transformer 14 from the signal transmission means 15.
The time dependency of the output change rate is 0.18% in 30 minutes, and the time dependency of the output change rate in the case of using the flat support means 19 is 1.2% in 30 minutes. , About 6.5 times the stability.

Further, when a load of 1 kg is applied and when 5 kg
The rate of change of the output of the piezoelectric transformer 14 when the load is applied is 32%, which is about 1.5 times higher than the rate of change of the output 22% when the flat supporting means 19 is used. Can be improved. This means that the support means 19
By making the elastic member used as the mesh into a mesh shape, frictional resistance and the like due to contact between the piezoelectric transformer 14 and the support means 19 can be reduced.
The output stability of the piezoelectric trough 14 is improved.
This is because the inhibition of the vibration can be reduced and the sensitivity is also improved.

Therefore, by forming the elastic member used as the support means 19 in a mesh shape, it is possible to improve both sensitivity and stability. In this embodiment, a mesh-like elastic member is used as the support means 19. However, a similar effect can be obtained even if the contact area between the piezoelectric transformer 14 and the support means 19 is reduced, for example, if the surface is spherical or convex. I have confirmed that it can be obtained.

(Embodiment 6) FIG. 9 shows a configuration diagram of a weight detecting apparatus according to Embodiment 6 of the present invention. In Embodiment 6, the load transmitting means 18 in Embodiments 1 to 5 are provided with fulcrums A, A force point B and an action point (C) are provided to reduce the load applied to the piezoelectric transformer 14.

The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, the load transmitting means 18 has one end as a fulcrum A, the other end as an operating point C for transmitting the load W to the piezoelectric transformer 14, and a force point B between the two for receiving the load W.
Is provided.

By doing so, it is possible to suppress the application of an impact load or a withstand load to the piezoelectric transformer 14, prevent the piezoelectric transformer 14 from being damaged, and improve the reliability as a weight detecting device. be able to.

Further, the weight detecting device having the configuration in which the load is applied indirectly as described above and the weight detecting device having the configuration in which the load is directly applied to the piezoelectric transformer 14 as shown in FIG. The relationship between the applied load W and the piezoelectric electromotive force V output by the piezoelectric transformer 14 is as shown in FIG. From this result, when a load is directly applied to the piezoelectric transformer 14, the change in the piezoelectric electromotive force output from the piezoelectric transformer 14 is large in the low load region,
It can be seen that as the applied load increases, the change in output also decreases. This is because the vibration of the piezoelectric transformer 14 is so small that a large load is applied, so that the vibration is greatly suppressed.

On the other hand, when a load is applied to the piezoelectric transformer 14 indirectly, for example, the load W applied to the piezoelectric transformer 14 is reduced to に よ っ て by providing the fulcrum A at a position １ ／ of the axis. Sensitivity, the load is 0
It can be improved about 1.2 times in the range of ５5 kg.

Further, in the low load range, for example, when the applied load was increased from 2 kg to 3 kg, the output change when the load was directly applied was 0.9 V, whereas the output change was 0.9 V. The output change at this time is 2.6 V, and the sensitivity can be improved about three times.

In this embodiment, the point of force B is provided between the fulcrum A and the point of action C. However, the position of the point of force B can be adjusted so that it can be moved. Can be adjusted. That is, since the load applied to the piezoelectric transformer 14 can be reduced by bringing the power point B closer to the fulcrum A, the sensitivity can be improved. By moving the power point B, the sensitivity can be selected as needed. it can.

(Embodiment 7) In Embodiment 7, the input electrodes 12a and 12b and the output electrode 1 in Embodiments 1 to 6 are used.
Lead wires 17a, 17b, 1 for taking out from 3a
7c which is hardly affected by the vibration of the piezoelectric transformer 14
A lead wire of 0.3 mm or more is used. When an oscillation signal is applied to the input electrodes 12a and 12b by the signal generating means 15, the piezoelectric transformer 14 vibrates. This vibration leads 1 to take out the piezoelectric electromotive force from the output electrode 13a.
7c, the lead wire 17c and the output electrode 1
Since a load is applied to the contact surface with 3a to suppress the vibration of the piezoelectric transformer 14, the output piezoelectric electromotive force becomes unstable, and the output electrode 13a is easily peeled off. Therefore, the piezoelectric transformer 1 is configured as described above.
4, an oscillation signal having a first resonance frequency of 32.5 kHz and an amplitude of 10 V was applied from the signal transmission means 15. That is, the time dependency of the output change rate is about 0.03% in 30 minutes, and φ
The stability can be improved about 10 times compared to the case where a lead wire of 0.3 mm or less is used.

[0060]

The present invention is embodied in the form described above and has the following effects.

According to the weight detecting device of the present invention, the oscillating signal from the signal generating means is provided to the piezoelectric transformer provided with the driving section in which the input electrode is formed on the piezoelectric ceramic plate and the power generating section in which the output electrode is formed. Is applied to oscillate the drive unit and output the output signal as piezoelectric electromotive force in the oscillating unit. If a load such as weight, atmospheric pressure, or liquid pressure is applied, the piezoelectric transformer vibrates according to the load. Since the characteristics change and the output signal also changes, the load applied can be easily detected with a simple configuration by calculating the output signal by the calculation unit.

According to the weight detecting device of the second aspect, since the piezoelectric transformer is provided with the power generation unit having the plurality of output electrodes, a plurality of output signals can be used as the detection signal. Reliable load detection is possible.
By making the output signals from the respective output electrodes different in magnitude, it is possible to select and output an output signal as required. By using the resonance frequency for the vibration of the piezoelectric transformer, the sensitivity of the output of the power generation unit to the load can be maximized, and the output sensitivity can be improved.

According to the weight detecting device of the third aspect, since the elastic member is used as the supporting means, the vibration of the piezoelectric transformer is absorbed, and the friction between the piezoelectric transformer and the supporting means is increased. , And fluctuate,
The stability of the output signal can be improved.

According to the fourth aspect of the present invention, since the supporting means is provided near the node of the vibration of the piezoelectric transformer, the vibration of the piezoelectric transformer is not hindered and the output signal is stabilized. Performance can be improved.

Further, according to the weight detecting device of the fifth aspect, since the elastic member used for the supporting means is formed so as to have a small contact area with the piezoelectric transformer, the resistance between the piezoelectric transformer and the supporting member is reduced. It is possible to improve the stability of the output signal of the piezoelectric transformer by reducing it.

According to the weight detecting device of the sixth aspect, since the load transmitting means is provided with the fulcrum, the power point, and the point of action, a small load can be indirectly applied to the piezoelectric transformer. In addition, the piezoelectric transformer can be prevented from being damaged. The relationship between the load applied to the piezoelectric transformer and the output is such that the lower the load, the greater the change in output. Therefore, the output sensitivity can be improved by applying a small load.

According to the weight detecting device of the present invention, since the position of the power point of the load transmitting means can be adjusted, the load applied to the piezoelectric transformer can be adjusted by moving the power point. The sensitivity can be selected as needed.

Further, according to the weight detecting device of the present invention, when the output signal from the input electrode and the output electrode of the piezoelectric transformer is taken out, the diameter which is hardly affected by the vibration is φ.
By using a lead wire of 0.3 mm or more, the suppression of vibration can be prevented and the stability of the output of the piezoelectric transformer can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a weight detection device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an electromotive force generated in a signal generation unit and a power generation unit in the weight detection device.

FIG. 3 is a characteristic diagram showing a relationship between a frequency of a signal generation unit and a piezoelectric electromotive force of a power generation unit in the weight detection device.

FIG. 4 is a characteristic diagram showing a relationship between a load applied in the weight detection device and a piezoelectric electromotive force output.

FIG. 5 is another configuration diagram of the weight detection device according to the second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between a driving time of a weight detection device and a piezoelectric electromotive force to be output according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a weight detection device according to a fourth embodiment of the present invention.

FIG. 8 is an exploded configuration diagram of a weight detection device according to a fifth embodiment of the present invention.

FIG. 9 is a configuration diagram of a weight detection device according to a sixth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing the relationship between the applied load of the weight detection device and the output piezoelectric electromotive force.

FIG. 11 is a configuration diagram of a conventional weight detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Piezoelectric ceramic plate 12 Drive part 12a, 12b Input electrode 13 Power generation part 13a, 13b, 13c13d Output electrode 14 Piezoelectric transformer 15 Signal generation means 16 Operation part 17a, 17b, 17c Lead wire 18 Load transmission means 19 Support means

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroyuki Ogino 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Masahiko Ito 1006 Odaka Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] 1. A piezoelectric transformer in which input electrodes are provided on upper and lower surfaces on one end face side of a piezoelectric ceramic plate to form a drive section, and output electrodes are provided on the other end face to form a power generation section. Load transmitting means for transmitting a load applied to the transformer, supporting means provided at a contact portion between the load transmitting means and the piezoelectric transformer, signal generating means for applying a frequency to the driving section, A weight detection device comprising: a calculation unit that calculates an applied signal by calculating an output signal. 2. A piezoelectric transformer comprising: a drive section formed by providing input electrodes on upper and lower surfaces on one end face side of a piezoelectric ceramic plate; and a power generation section formed by providing a plurality of output electrodes on the other end face. The weight detection device according to claim 1. 3. The weight detecting device according to claim 1, further comprising a supporting means formed of an elastic member. 4. The weight detecting device according to claim 1, wherein the supporting means is provided near a node of vibration of the piezoelectric transformer. 5. The weight detecting device according to claim 1, wherein the elastic member forming the supporting means is configured to reduce a contact area with the piezoelectric transformer. 6. The weight detecting device according to claim 1, wherein a fulcrum, a force point, and an action point are provided on the load transmitting means. 7. The weight detecting device according to claim 6, wherein the position of the point of force of the load transmitting means is adjustable. 8. The weight detecting device according to claim 1, wherein a lead wire having a diameter exceeding 0.3 mm is used for taking out an input electrode and an output electrode of the piezoelectric transformer.