JPH07270261A - Contact force and tactile sensor using piezoelectric vibration having three-terminal structure - Google Patents

Abstract

PURPOSE:To obtain a contact force and tactile sensor using a piezoelectric vibrator having a three-terminal structure which has a strong noise resistance and a high resolution and can be made small in size. CONSTITUTION:When an oscillation circuit 102 makes oscillation, vibration is generated under an electrode 103a by a reverse piezoelectric effect. Under an electrode 103b, vibration caused by the vibration generated in an electrode 103c and propagated therefrom is present, and that vibration becomes piezoelectric vibration in the electrode l03b and an electric charge is generated. By the propagation of the vibration from the electrode 103c to the electrode 103b, at this time, signals other than the one near a resonance frequency f0 of a three-terminal piezoelectric vibrator 103 are filtered and removed. When noise comes in the oscillation circuit 102, for instance, a signal in a band narrower than the band of DELTAf can be taken out of a signal outputted from an output terminal 106, while the noise in the band of DELTAf comes in a signal outputted from an output terminal 107.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor for detecting a reaction force received when it comes into contact with an object having a viscoelastic characteristic, and particularly for a pressure sensor provided in an instrument inserted into a body cavity such as an endoscope or a catheter. , Tactile sensor.

[0002]

2. Description of the Related Art In recent years, endoscopes have come to emphasize the function of manipulating an observation object while observing, rather than the function as an instrument for observing the inside of a body cavity or the like. This can be more easily deduced from the situation where a rigid endoscope is used for cholecystectomy. Surgery and diagnosis using an endoscope are expected to expand in the future.

Further, since a catheter inserted into a blood vessel in the brain is used in the brain in which mistakes in use lead to human life, it is necessary to sense the state of contact with the blood vessel and prevent injury due to catheter insertion. is there. The treatment of the brain is mainly surgical, and the physical burden on the patient is very large. Therefore, medical treatment that uses a catheter or the like and has a relatively small physical burden on the patient is desired.

As described above, pressure information and tactile information as well as visual information are important in order to appropriately perform diagnosis and treatment in a more complicated and fine operation body cavity. Therefore, as a structure for obtaining pressure and tactile information, it is conceivable to dispose pressure and tactile sensors on the wall surface of the endoscope or the wall surface of the catheter. As a result, contact with a body cavity such as an internal organ or a blood vessel can be performed without causing pain to the patient, and surgery can be performed with minimal invasiveness. Note that such a sensor must be provided in a very small portion.

As described above, pressure and tactile information is an important issue in the future medical care. It should be noted that the pressure sense here is defined as the perception of reaction force due to the viscoelastic property of the object, and the tactile sense is a higher level of perception than the pressure sense, and the hardness determined by the viscoelastic property and their structure. It is defined as the perception of softness. Here, the tactile sense, which is a higher level of perception than the pressure sense, is as follows.
It is considered to be composed of two elements. The first is viscoelastic property, the second is non-linearity of viscoelastic property, and the third is anisotropic. The viscoelastic property is the mechanical impedance of the surface of the object, and the non-linearity of the viscoelastic property affects the mechanical impedance of the contact part in the depth direction except the contact part, which has different mechanical impedance. That is, the anisotropy is defined as a characteristic in the direction perpendicular to the surface of the object and in the direction along the surface of the object. This is for example
It is empirical that the sense of hardness on the surface is different when the contact part is connected to hard tissue such as bone in the living body and when the contact object does not contact other things such as dangling I know. Therefore, a sensor that detects the viscoelastic characteristic of the object as a mechanical impedance is called a pressure sensor, and a sensor that detects a plurality of three tactile components is called a tactile sensor.

In response to such needs, it is conceivable to use a piezoelectric vibrator as a sensor principle which can be expected to detect with high sensitivity and high reliability. An example in which a piezoelectric vibrator is used as the pressure sensor or the tactile sensor is used. There was no. In addition,
Although the fields of application are completely different, the following are examples of using this piezoelectric vibrator for a sensor.

As an example, there is a quartz oscillator gas sensor which is a sensor using a quartz oscillator as an odor sensor. In this method, an adsorption film is applied to a crystal oscillator, and a change in vibration characteristics due to an odor substance adhering to the adsorption film is sensed to detect the intensity of the odor. It is considered that this change is due to a change in the oscillation frequency caused by the mass loading effect of the odor substance and a change in the viscoelasticity of the adsorption film. As a crystal oscillator gas sensor based on this method, a technical report of the Institute of Electronics, Information and Communication Engineers (US9
3-7 1993-05) and the like are known. The crystal oscillator gas sensor will be described below.

FIG. 38 (a) is a circuit diagram of the above crystal oscillator gas sensor, and FIG. 38 (b) is a diagram showing an equivalent circuit near the resonance frequency of the crystal oscillator on this circuit diagram. Here, Z _3e represents impedance due to mass load and viscoelastic change. From the equivalent circuit shown in FIG. 38 (b), the admittance of the crystal unit is

[0009]

[Equation 1] Is given. Where Y _d is the braking admittance, Y
_mot is called dynamic admittance, C ₀ is called a binding capacitance, and C ₁ is called a piezoelectric capacitance. When there is no load than this, the resonance frequency f _r0 and the anti-resonance frequency f _a0 are

[0010]

[Equation 2] Is expressed as When a mass change occurs due to the adsorption of odor molecules, Z _3e becomes an inductive reactance, and as a result, the resonance frequency f _r1 and the anti-resonance frequency f _a1 decrease as given by the following equation.

[0011]

[Equation 3] In addition, when the viscoelastic change of the membrane occurs due to adsorption, Z _3e
Since has both inductive reactance and resistance components, the resonance resistance also changes significantly.

As another example, JP-A-3-8164
There is a tactile sensor disclosed in Japanese Patent No. This method uses a vibrator 3601 and a vibrator 360 as shown in FIG.
The vibration detecting element 3602 attached to the No. 1 amplifier circuit 36
03, frequency measuring device 3604 or voltage measuring device 360
Self-exciting circuit 36 composed of measuring section 3606
The signal from the vibration detecting element 3602 is amplified by an amplifier circuit 3603 and fed back to a vibrator 3601 for self-excitation. Then, the natural frequency when not in contact with the target object and the natural frequency when in contact with the target object are obtained from the frequency detected by the vibration detecting element 3602 attached to the vibrator 3601. ,
An apparatus and method for detecting the hardness and softness of an object from the difference between the two.

[0013]

However, in the above-described crystal oscillator gas sensor of the conventional example, when an oscillation circuit is assembled, a terminal that configures the circuit and a terminal that monitors the output are shared, and noise that enters the circuit is eliminated. It is considered that the noise resistance is weak due to the influence.

Further, in the above-mentioned tactile sensor of the conventional example, since the vibration detecting element 3602 is attached to the contact portion with the object, miniaturization becomes very difficult. Further, in order to increase the detection resolution, it is necessary to have a large resonance sharpness (Qm). However, when the vibration detecting element 3602 is attached to the vibrator as described above, the resonance sharpness is significantly lowered and the sensitivity is lowered. I will end up. Further, since this tactile sensor can measure only the mechanical impedance at the contact surface with the object, it cannot be said that the tactile sensor defined above.

The present invention has been made in order to solve the above problems, and uses a piezoelectric vibrator having a strong noise resistance, a high resolution, and a three-terminal structure capable of being downsized. It is an object to provide a pressure sensor and a tactile sensor.

[0016]

In order to solve the above-mentioned problems, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to claim 1 makes a vibrator contact an object,
In a pressure sensor that detects a viscoelastic characteristic of the object as an electric signal based on a characteristic change of the vibrator, the vibrator is a piezoelectric vibrator, and one surface of the piezoelectric vibrator includes a first electrode and a second electrode. Of the first electrode and the second electrode, and two electrodes of the third electrode on the other side of the piezoelectric vibration. To form an oscillation circuit by connecting to a circuit that oscillates using the equivalent circuit constant of the child, and to use an electrode of the first electrode and the second electrode that does not form the oscillation circuit as an output terminal. Is characterized by.

A tactile sensor using a piezoelectric vibrator having a three-terminal structure according to claim 2 detects the vibration response from the piezoelectric vibrator by applying a pulse by bringing the piezoelectric vibrator into contact with an object. By doing so, in the tactile sensor that detects two or three characteristics among the viscoelastic characteristic, the non-linearity, and the anisotropy of the object, the energy trapping-type first sensor is provided on one surface of the piezoelectric vibrator. Electrode and second
And three electrodes of an energy trap type third electrode on the other surface, and a pulse is applied between any one of the first electrode and the second electrode and the third electrode. Pulse applying means for applying a signal, and vibration of the piezoelectric vibrator output between the remaining one electrode of the first electrode and the second electrode and the third electrode by the applied pulse signal. And a detection means for detecting a response.

Further, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a third aspect of the invention is such that a vibrator is brought into contact with an object and the viscoelastic characteristic of the object is changed by changing the characteristics of the object. Of the piezoelectric vibrator, the piezoelectric vibrator includes a first electrode and a second electrode on one surface of the piezoelectric vibrator, and a third electrode on the other surface.
The first electrode and the second electrode.
Is connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator to form an oscillation circuit, and one of the first electrode and the second electrode serves as an output terminal. It is characterized by doing.

[0019]

In the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the present invention, the vibrator is brought into contact with the object and the viscoelastic characteristic of the object is detected as an electric signal by the characteristic change of the vibrator. In the pressure sensor having means, the vibrator is a piezoelectric vibrator, and the first electrode and the second electrode are provided on one surface of the piezoelectric vibrator, and the three electrodes of the third electrode are provided on the other surface. Have. Then, either one of the first electrode or the second electrode and the two electrodes of the third electrode are connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator and oscillate. A circuit is formed, and one of the first electrode and the second electrode that does not form the oscillation circuit is used as an output terminal.

Further, a tactile sensor using a piezoelectric vibrator having a three-terminal structure, the piezoelectric vibrator is brought into contact with an object,
A tactile sensor having detection means for detecting two or three characteristics among the viscoelastic characteristics, nonlinearity, and anisotropy of the object by detecting the vibration response from the piezoelectric vibrator due to pulse application. At one surface of the piezoelectric vibrator, the energy confinement type first electrode and the second electrode
And the above three electrodes of the energy trap type third electrode on the other surface. Then, a pulse signal is applied between the one of the first electrode and the second electrode and the third electrode by the pulse oscillating means,
The vibration response of the piezoelectric vibrator due to the pulse signal output between the third electrode and the remaining one electrode of the first electrode and the second electrode is detected by the detection means.

A pressure sensor using a piezoelectric vibrator having a three-terminal structure makes the vibrator contact an object and detects the viscoelastic characteristic of the object as an electric signal by changing the characteristic of the object. In the pressure sensor having a detection means, the vibrator is a piezoelectric vibrator, and the three electrodes of the first electrode and the second electrode on one surface of the piezoelectric vibrator and the third electrode on the other surface thereof. It has electrodes. And the first
The electrode and the second electrode are connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator to form an oscillation circuit. Further, one of the first electrode and the second electrode serves as an output terminal.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the structure of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the first embodiment of the present invention.

The first embodiment is a three-terminal piezoelectric vibrator 103.
Electrode 103b and electrode 103c on the front surface and electrode 10 on the back surface
It has three terminals 3a and 2 of electrodes 103a and 103c.
The terminal is the equivalent circuit constant LCR of the three-terminal piezoelectric vibrator 103.
The components are connected to a circuit 105 that can configure an oscillation circuit, and the oscillation circuit 102 is configured from this.

The pressure sensor 104 has an output terminal 106 for outputting an output signal from the electrode 103b and a detection circuit 108 for detecting a sensor signal from the output terminal 106.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the first embodiment will be described.

In the oscillation circuit 102, the three-terminal piezoelectric vibrator 103 is in a vibrating state depending on the characteristics of the three-terminal piezoelectric vibrator such as the impedance characteristics of the three-terminal piezoelectric vibrator 103.

On the other hand, FIG. 2 is a diagram showing a configuration of an oscillation circuit using a two-terminal piezoelectric vibrator which is known as a conventional example. Oscillation circuit 20 using two-terminal piezoelectric vibrator 203
2 has the same basic configuration as the oscillation circuit 102 using the three-terminal piezoelectric vibrator 103 shown in FIG. 1, but is different from the oscillation circuit 102 in that the electrode 203b is a circuit 205 and an output terminal to the outside. 207 is shared.
Therefore, in the oscillator circuit 102, the output terminal is connected to the electrode 10.
The output terminal 107 from 3c is equivalent to the circuit shown in FIG.

The frequency bands of the output signals from the output terminal 107 from the oscillator circuit 102 shown in FIG. 1 and the output terminal 207 from the oscillator circuit 202 shown in FIG.
It becomes as shown in FIG.

On the other hand, the frequency band of the output signal from the electrode 103b (output terminal 106) is as shown in FIG. 3 (a). This is based on the following principle.

In FIG. 1, when the oscillator circuit 102 is oscillating, vibration occurs under the electrode 103a due to the inverse piezoelectric effect. Therefore, it becomes the same as the signals in the frequency bands of both the circuit 205 and the piezoelectric vibrator 203 in FIG.

On the other hand, in the portion below the electrode 103b,
There is vibration due to the propagation of the vibration generated in the electrode 103c, and this vibration becomes piezoelectric vibration in the electrode 103b to generate electric charges.

At this time, the electrodes 103c to 103b
Due to the vibration propagation to, the signals other than the signal in the vicinity of the resonance frequency f ₀ of the three-terminal piezoelectric vibrator 103 are filtered and removed. For example, when noise enters the oscillation circuit 102,
Although the signal output from the output terminal 107 has noise in the Δf ′ band, the signal output from the output terminal 106 can take out a signal in the Δf ′ band which is narrower than the Δf ′ band. Therefore, the signal from the electrode 103b of the three-terminal piezoelectric vibrator 103 becomes a signal in the frequency band as shown in FIG.

The pressure sensor 104 uses the three-terminal piezoelectric vibrator 103 as a probe, and the three-terminal piezoelectric vibrator 1 is used.
Since the pressure sense information 101 is detected from the characteristic change of 03, the pressure sense information 101 is not removed by the filter effect.

The output signal output from the output terminal 106 is output at the resonance frequency f ₀ of the three-terminal piezoelectric vibrator 103 as shown in FIG.
It is output with the amplitude corresponding to the real part of the impedance of. The viscoelastic property of the object is calculated from this output signal.
The natural frequency, which is the resonance frequency f ₀ , and the impedance can be obtained from an equivalent circuit.

The electrodes 103a of the three-terminal piezoelectric vibrator 103,
The equivalent circuit in 103c can be regarded as equivalent to the piezoelectric vibrator 203. Therefore, considering the equivalent circuit of the piezoelectric vibrator 203, the output signal from the three-terminal piezoelectric vibrator 103 can be expressed as shown in FIG. 5 using the Mason equivalent circuit 501. When this equivalent circuit is developed in the vicinity of the resonance frequency f ₀ , FIG.
Can be expressed like the LCR circuit 601. This LCR
Using the circuit 601, the resonance frequency f _r and the anti-resonance frequency f _a
And the impedance Z can be obtained by the following equation.

[0037]

[Equation 4] Therefore, the output signal f ₀ shown in FIG.
Corresponding to _r , V is proportional to Z. The detection circuit 108 detects the above f ₀ and V.

Next, consider that the viscoelastic body that gives the pressure information 101 comes into contact with the three-terminal piezoelectric vibrator 103. It is said that the viscoelastic body can divide the characteristics of stress and strain into two components. This is an elastic stress in which the stress and strain have the same phase, and a viscous stress in which the strain phase advances 90 ° with respect to the stress. Considering this as an equivalent circuit, the elastic stress is the resistance and the viscosity. Stress corresponds to reactance. Therefore, the equivalent circuit of the viscoelastic body is shown in FIG.
It is composed of ΔR ₁ and ΔL ₁ as shown in (c). A state in which a load such as a viscoelastic body is brought into contact with the three-terminal piezoelectric vibrator 103 is equivalent to one connected in series to an equivalent circuit. Therefore, when the viscoelastic body comes into contact, the resonance frequency f _r , the anti-resonance frequency f _a , and the impedance Z in the above equation are changed to f _r1 , f _a1 , and Z ₁ given by the following equations.

[0039]

[Equation 5] Therefore, as shown in FIG. 4A, the amplitude of the output signal is Δ
V becomes smaller, and the cycle of the output signal becomes shorter by the time Δt per cycle as shown in FIG. 4B, that is, the oscillation frequency of the output signal becomes smaller. By detecting each of these values, the contact state of the viscoelastic body can be detected.

As described above, according to the first embodiment, since the three-terminal piezoelectric vibrator has the three-terminal electrode structure, only the signal in the frequency band f ₀ can be detected, and the pressure sense It is possible to detect the signal of the sensor 104 as a signal with less noise.

Next, a pressure sensor using the piezoelectric vibrator having the three-terminal structure of the second embodiment according to the present invention will be described.

The structure of the second embodiment is the same as that of the first embodiment shown in FIG. 1 except that the area ratio of the electrode 103b to the electrode 103c is 0.1 to 1 and the other structures are the same. Are the same.

The second embodiment is a three-terminal piezoelectric vibrator 103.
Electrode 103b and electrode 103c on the front surface and electrode 10 on the back surface
3a of 3 terminals, and the electrode 10 of the electrode 103b.
The area ratio to 3c is 0.1 to 1, and the electrode 103
The two terminals of a and the electrode 103c are the three-terminal piezoelectric vibrator 1
Is connected to a circuit 105 that can configure an oscillation circuit using the equivalent circuit constant LCR component of 03.
Is configured.

Further, an output terminal 106 for outputting an output signal from the electrode 103b and a detection circuit 108 for detecting a sensor signal from the output terminal 106 are provided, and the pressure sensor 104 is constituted by them.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the second embodiment will be described.

In the three-terminal piezoelectric vibrator 103, the electrodes 103a and 103c, which are two terminals of the three terminals, are connected to the circuit 105.
Connected to the electrode 1 of the three-terminal piezoelectric vibrator 103.
03a, the electrode 103c and the circuit 105
2 is configured.

At this time, the 3-terminal piezoelectric vibrator 103 is in a vibrating state depending on the characteristics of the 3-terminal piezoelectric vibrator 103 such as the impedance characteristics of the 3-terminal piezoelectric vibrator 103. The frequency band of the output signal from the electrode 103b becomes a signal in the frequency band as shown in FIG.

On the other hand, the electrode 103b (output terminal 10
The amplitude of the output signal from 6) is as shown in FIG.
It is determined by the area ratio of 03b to the electrode 103c. This is because in the portion below the electrode 103b, the electrode 103c
There is vibration due to the propagation of the vibration that is occurring at
In 03b, this vibration becomes a piezoelectric vibration and a charge Q is generated. It is the electrode 103b that outputs the voltage V (= Q / C) due to this charge Q.

If the voltage applied to the electrode 103c is constant, the generated charge Q is also constant, and in order to increase the voltage V, it is conceivable to reduce the capacitance C. Since the capacitance C is proportional to the electrode area, the electrode 103
When the area of b is reduced, the voltage V output from the electrode 103b increases. Here, the electrode 1 of the electrode 103b
The area ratio to 03c is preferably small, but S /
Considering securing N and mounting necessary lead wires, 0.1 or more is desirable.

On the other hand, for the purpose of amplification, the amplification is not performed when the area ratio is 1 or more, so the upper limit was made less than 1. Therefore, the output signal as shown in FIG. 4 can be amplified by the above structural characteristics of the three-terminal piezoelectric vibrator 103.

As described above, in the second embodiment,
Electrode 103c of electrode 103b of 3-terminal piezoelectric vibrator 103
The ratio is set to 0.1 to 1. As a result, the output from the three-terminal piezoelectric vibrator 103 forming the pressure sensor 104 is output from the oscillation circuit 102, which is a sensing circuit, without using a circuit such as a charge amplifier.
The amplified signal can be output from the output terminal 106.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the third embodiment of the present invention will be described.

FIGS. 8 (a) and 8 (b) show a third embodiment of the present invention.
It is a figure which shows the structure of the pressure sensor using the piezoelectric vibrator which has a 3-terminal structure of an Example.

The third embodiment is an energy trapping type three-terminal piezoelectric vibrator 803 as shown in FIG. 8A, and the electrodes 803b and 803c are formed on the surface of the energy trapping type three-terminal piezoelectric vibrator 803. And the electrode 803 on the back
It has three terminals a, and the sum of the area of the electrode 803a and the area of the electrode 803b is substantially equal to the area of the electrode 803c.

FIG. 8B is a diagram showing a structure of a pressure sensor using the energy trapping type three-terminal piezoelectric vibrator 803.

2 of the electrode 803a and the electrode 803c
The terminal is the equivalent circuit constant LCR of the three-terminal piezoelectric vibrator 803.
The components are connected to a circuit 105 that can configure an oscillation circuit, and thus the oscillation circuit 102 is configured.

Further, an output terminal 106 for outputting an output signal from the electrode 803b and a detection circuit 108 for detecting a sensor signal from the output terminal 106 are provided, and the pressure sensor 104 is constituted by them.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the third embodiment will be described.

Energy trapping type three-terminal piezoelectric vibrator 80
3, the electrode 803a and the electrode 803c, which are two terminals of the three terminals, are connected to the circuit 105, and the electrode 803a and the electrode 80 of the energy trap type three-terminal piezoelectric vibrator 803 are connected.
The oscillator circuit 102 is configured by 3c and the circuit 105.

At this time, the energy-trapping type three-terminal piezoelectric vibrator 803 is in a signal state depending on the characteristics of the three-terminal piezoelectric vibrator, such as the impedance characteristics of the energy-trapping type three-terminal piezoelectric vibrator 803. This electrode 80
The frequency band of the output from 3b becomes a signal in the frequency band as shown in FIG.

However, the commonly used piezoelectric vibrator 20
Taking the 2-terminal piezoelectric vibrator as an example, the piezoelectric body 3 has electrodes 901a and 901b attached to the entire surface of the material of the piezoelectric vibrator 203 as shown in FIG. Therefore, depending on the shape of the vibrating portion determined by the electrodes 901a and 901b, a vibration waveform different from the ideal state is generated. This is related to the division of vibration near the anti-resonance point of the impedance characteristic and the reduction of the Qm value.

Therefore, in order to remove these, FIG.
Energy trap type three-terminal piezoelectric vibrator 8 shown in (a)
Use 03. In order to explain the characteristics of the energy trapping type three-terminal piezoelectric vibrator 803, the energy trapping type two-terminal piezoelectric vibrator will be described as an example. FIG. 10 shows a front view and a side view of the energy trap type two-terminal piezoelectric vibrator 1003. This energy trap type two-terminal piezoelectric vibrator 1003 has an electrode 1003a on one surface thereof,
An electrode 1003b is provided on the other surface, and the areas of these electrodes are smaller than the entire area of the energy trap type two-terminal piezoelectric vibrator 1003 and the thickness thereof is also thin. This should generally satisfy the conditions given by

[0063]

[Equation 6] Here, a: width of electrode 2h: thickness of piezoelectric vibrator ρ: density of piezoelectric vibrator 2h ′: thickness of electrode ρ ′: density of electrode. In the energy confinement type two-terminal piezoelectric vibrator 1003 formed to meet such a condition, vibration is generated only in the electrodes 1003a and 1003b facing each other. Usually, the vibration spreads to the wave source at that portion, but in this case, the vibration is caused by the electrodes 1003a and 1003.
Trapped just below b.

This is for the following reason. The energy trap type two-terminal piezoelectric vibrator 1003 vibrates according to an input signal due to an inverse piezoelectric effect. This vibration has a frequency according to the thickness of the energy trap type two-terminal piezoelectric vibrator 1003. Focusing on the energy at this time, the energy E
Is proportional to the Planck's constant h and the frequency ν.

[0065]

[Equation 7] The frequency ν is given by the following equation.

V = ν · λ The wavelength λ has the following relationship due to the difference in the thickness of the cross section.
However, the electrode part and the electrodeless part were distinguished by suffixes 1 and 2.

Since λ1> λ2 and the sound velocity v is constant, ν1 <ν2, and E1 <E2 where E1 is the energy directly below the electrode and E2 is the energy of the electrodeless portion. That is, it can be seen that the energy directly below the electrode is lower than that in the surrounding area. However, considering that energy generally moves to the lower side, E1 is always supplied with energy from E2, and eventually energy is confined directly under the electrode.

Further, by adopting the energy confinement type electrode structure, the vibration state immediately below the electrode does not change even if a factor such as a mass load that affects the vibration is applied around the electrode.

Therefore, as shown in FIG.
3a and 1003b, take-out electrodes 1003aL and 100
3 bL can be attached without affecting vibration, and an ideal vibration state and a high Qm value can be maintained.

A similar phenomenon occurs in a three-terminal structure, and a high Qm value can be maintained by constructing the three-terminal structure with energy trapping electrodes as shown in FIG. 8 (a).

The shape of the electrodes of the energy-trap type three-terminal piezoelectric vibrator at this time is not limited to the rectangular shape shown in FIG. 8A, but may be another shape such as a round shape.

As described above, according to the third embodiment, by adopting the energy confining electrode structure, it becomes possible to generate vibration at a value close to the theoretical value, and to provide a pressure sensor having high sensitivity. Is possible.

Next, a pressure and tactile sensor using the piezoelectric vibrator having the three-terminal structure according to the fourth embodiment of the present invention will be described.

FIG. 11 is a diagram showing the structure of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the fourth embodiment of the present invention.

The fourth embodiment is a three-terminal piezoelectric vibrator 103.
Electrode 103b and electrode 103c on the front surface and electrode 10 on the back surface
It has three terminals 3a and 2 of electrodes 103a and 103c.
The terminal is connected to a circuit 105 composed of an inverter 1106, a resistor 1107, capacitors 1108a and 1108b, and an equivalent circuit constant L of the above-described three-terminal piezoelectric vibrator 103.
An oscillation circuit 102 that oscillates using the CR component is configured. This oscillator circuit 102 is called a pierce circuit.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the fourth embodiment will be described.

The oscillating circuit 102 is composed of a power amplifier and a feedback circuit. In order for the circuit to oscillate, the gain Ga of the power amplifier and the attenuation Gf of the feedback circuit are in a relationship of Gf ≤ Ga, and further, the output side of the power amplifier. If the output fed back to the input side is positive feedback, that is, if it has the same phase, it will oscillate.

In FIG. 11, the inverter 1106 and the resistor 1107 determine the phase inversion and the feedback amount, and the three-terminal piezoelectric vibrator 103 causes the phase inversion. As a result, the output side and the input side of the power amplifier have the same phase, and the oscillator is configured.

Here, the inverter 11 is added to the oscillation circuit 102.
When a voltage for driving 06 is applied, it becomes an oscillating state and oscillates at the oscillation frequency of the three-terminal piezoelectric vibrator 103.

The pressure information 101 due to contact with the object is
The signal is detected on the contact surface of the three-terminal piezoelectric vibrator 103 having a three-terminal electrode structure, and the signal is detected by one electrode 103 of the three-terminal circuit.
This is performed by the detection circuit 108 connected to b.

FIG. 12 is a block diagram showing the flow of this detection processing. The output signal 3201 from the oscillation circuit 102 shown in FIG. 11 is measured in frequency and amplitude by the frequency detection circuit 3202 and the amplitude detection circuit 3203. Then, the measured signal and the signal when there is no load on the three-terminal piezoelectric vibrator body 103 shown in FIG. 11 are compared by the comparator 3204 and output as the output 3205 of the viscoelastic characteristic.

The amplitude detection circuit 3203 is composed of a peak detector, and the frequency detection circuit 3202 is composed of a counter.

Further, FIG. 13 is a block diagram showing a flow of processing in the comparator 3204. First, blank measurement 3101 is performed under no load condition, and frequency detection 3106 and amplitude detection 31 are performed from the oscillation signal output at that time.
07, and the detection data is stored in the memory 3108.

After that, in the pressure sense measurement 3112, the object comes into contact with the three-terminal piezoelectric vibrator 103 3102, the oscillation signal at that time is measured 3103, and the frequency detection 3104 and the amplitude detection 3105 are performed based on the measured oscillation signal. Then, the frequency and amplitude of this detection data are compared by the comparator 3109.
Is compared with the frequency and amplitude of the detection data detected by the blank measurement 3101 stored in the memory 3108 and stored in the memory 3108.
Set to 10. Note that FIG. 12 is a block 311 in FIG.
Equivalent to 1.

The output signal output from the output terminal 106 is as shown in FIGS. 4 (a) and 4 (b). This output signal is output at the resonance frequency f ₀ of the three-terminal piezoelectric vibrator 103, and is output with an amplitude corresponding to the real part of the impedance of the three-terminal piezoelectric vibrator 103. Therefore, FIG.
The output signal f ₀ shown in (a) corresponds to f _r in the above equation,
V is proportional to Z. The detection circuit 108 detects the above f ₀ and V.

Next, when the viscoelastic body comes into contact with the oscillation circuit 102, the resonance frequency f _r , the anti-resonance frequency f _a , and the impedance Z of the above formulas f _r1 , f _a1 shown in the above formula (1),
Change to Z ₁ .

Therefore, the amplitude of the output signal is reduced by ΔV as shown in FIG. 4A, and the cycle of the output signal is shortened by the time Δt per cycle as shown in FIG. 4B.
That is, the oscillation frequency of the output signal decreases. By detecting each of these values, it becomes possible to detect the viscoelastic characteristics of the viscoelastic body.

The electrode structure of the three-terminal piezoelectric vibrator 103 may have a rectangular shape as shown in FIG. 8, but the shape is not limited to the rectangular shape as long as the energy can be efficiently trapped. May be.

The oscillator circuit 102 is not limited to the Pierce circuit, and any other circuit may be used as long as it is an oscillator circuit configured by using the equivalent circuit constant of the three-terminal piezoelectric vibrator 103.

Further, as the piercing circuit, one having the same function as that of the inverter may be used. For example, even if two input terminals of the AND circuit are combined and used as one input terminal, the same characteristic is obtained. Therefore, an AND circuit may be used.

As described above, in the fourth embodiment, the Pierce circuit is used, and since the oscillation occurs between the resonance frequency and the anti-resonance frequency, the frequency adjustment becomes unnecessary and the circuit Adjustment becomes easy.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the fifth embodiment of the present invention will be described.

FIG. 14 is a diagram showing the structure of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the fifth embodiment of the present invention.

In the fifth embodiment, the energy trap type 3 is used.
The electrode 803b and the electrode 80 are provided on the surface of the terminal piezoelectric vibrator 803.
3c, which has three terminals of an electrode 803a on the back surface,
03a and the two terminals of the electrode 803c are connected to a circuit 105 that can configure an oscillation circuit using the equivalent circuit constant LCR component of the piezoelectric vibrator, and the oscillation circuit 102 is configured from this.

Further, an output terminal 106 for outputting a signal from the electrode 803b, an output terminal 107 for outputting a signal from the electrode 803c, an output terminal 106 and an output terminal 107.
1201 for adding the signals from the adder 1201 and the detection circuit 12 for detecting the sensor signal from the adder 1201.
03, and these constitute the pressure sensor 1204.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the fifth embodiment will be described.

Energy-confining 3-terminal piezoelectric vibrator 80
The equivalent circuit of 3 can be expressed as shown in FIG. The outline of the operation of this equivalent circuit shows the same effect as that in which two vibrators are confined on one piezoelectric ceramic plate and a phase inversion transformer is built in. That is,
When a signal is applied to the electrodes 803c and 803a, the electrodes 8
A signal whose phase is inverted is output from 03b and the electrode 803a. Therefore, the output signal from the electrode 803c and the electrode 8
The phase of the output signal from 03b is inverted.

On the other hand, the pressure sensation information 101 input by contacting the energy-trapping type three-terminal piezoelectric vibrator 803 uniformly enters into the electrodes 803b and 803c as mechanical signals, and the energy-trapping type three-terminal piezoelectric vibrator 803 outputs an electric signal. Converted to A. This electrode 803b and electrode 80
The signals from 3c are in phase. FIG. 16 shows the summary of these signals.

When the signals from the output terminals 106 and 107 are added by the adder 1201, the oscillation signal S is removed from the output terminal 1202, and the pressure signal A is doubled and output. Further, even if the noise S ′ enters the oscillator circuit 102, the phases are inverted between the output terminal 107 and the output terminal 106, so that the noise S ′ is removed by the adder 1201.

As described above, the pressure signal A can be detected even with the configuration in which the output signal from the output terminal 106 as described in the first embodiment is directly input to the detection circuit 108, but noise is generated in the output signal. May be mixed in. However, with the configuration of the fifth embodiment, the noise resistance is strong and the noise in the frequency band Δf shown in FIG. 3 can be removed.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the sixth embodiment of the present invention will be described.

FIG. 17 is a diagram showing the structure of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the sixth embodiment of the present invention.

In the sixth embodiment, the energy trap type 3
The electrode 803b and the electrode 80 are provided on the surface of the terminal piezoelectric vibrator 803.
3c and three terminals of an electrode 803a on the back surface.
The two terminals of a and the electrode 803c are connected to the circuit 105 that can configure the oscillation circuit using the equivalent circuit constant LCR component of the piezoelectric vibrator, and the oscillation circuit 102 is configured.

A phase shifter 1401 for shifting the output signal from the electrode 803b, an output terminal 1402 for outputting the output signal, an output terminal 107 for outputting an output signal from the electrode 803c, and the output An adder 1201 for adding the outputs from the terminal 1402 and the output terminal 107
And a detection circuit 1203 for detecting the sensor signal from the adder 1201.
4 are configured.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the sixth embodiment will be described.

An equivalent circuit of the three-terminal energy trap type three-terminal piezoelectric vibrator 803 can be represented as shown in FIG. The outline of the operation of this equivalent circuit shows the same effect as that of confining two vibrators on one piezoelectric ceramic plate and further incorporating a phase inversion transformer. That is, when a signal is applied to the electrodes 803c and 803a, the electrodes 803
Signals with inverted phases are output from b and the electrode 803a. Therefore, the output signal from the electrode 803c and the electrode 803
The phase of the output signal from b is inverted.

However, considering the phenomenon of vibration propagation, there is a possibility that the phase may not be completely inverted.
Therefore, in the configuration shown in FIG. 14, the adder 1201 may not be able to accurately remove the oscillation signal and noise. Therefore, in the sixth embodiment, a phase shifter 1401 that can be adjusted so as to completely invert the output signal from the electrode 803b to the output terminal 107 is provided.

Thus, when the output signal from the electrode 803b is input to the phase shifter 1401, the output terminal 1402 and the output terminal 1 for outputting the output signal from the phase shifter 1401.
The output of the oscillation signal S of 07 and the noise S ′ are completely inverted, and the adder 1201 outputs the oscillation signal S and the noise S ′.
Can be removed.

As described above, the fifth signal shown in FIG.
In the embodiment, in the configuration in which the output signal from the output terminal 106 and the output signal from the output terminal 107 are directly input to the adder 1201, noise may be mixed in the output signal. However, with the configuration of the sixth embodiment, the noise resistance is strong and it is possible to remove the noise accurately within the frequency band Δf shown in FIG.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the seventh embodiment of the present invention will be described.

FIG. 18A is a view of a piezoelectric vibrator having a three-terminal structure according to the seventh embodiment of the present invention as viewed from the two-terminal side, and FIG. 18B is a sectional view thereof.

In the seventh embodiment, the polarization direction 1501 of the energy confining type three-terminal piezoelectric vibrator 803 used in FIG. 8 is changed to the electrode 803 as shown in FIG. 18B.
a, or the direction perpendicular to the electrodes 803b and 803c, that is, the surface in contact with the object is polarized in the thickness direction.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the seventh embodiment will be described.

The polarization direction 150 as shown in FIG.
1, the electrode 803a, the electrode 80 as shown in FIG.
An energy trapping type three-terminal piezoelectric vibrator 80 that comes into contact with an object by the oscillation circuit 102 composed of two terminals 3c.
The surface of 3 vibrates in the thickness direction. Therefore, for example, a living body has anisotropy of viscoelasticity due to tendons and the like, but by vibrating in the vertical direction with respect to an object in this manner, the viscoelasticity in the vertical direction can be detected.

Therefore, in the seventh embodiment, it is possible to detect the viscoelastic characteristic in the longitudinal direction as the mechanical impedance in the viscoelastic characteristic of the anisotropic object.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the eighth embodiment of the present invention will be described.

In the eighth embodiment, as shown in FIG. 18C, the polarization direction 1501 of the energy trap type three-terminal piezoelectric vibrator 803 used in FIG.
a, or a direction parallel to the electrodes 803b and 803c,
That is, the surface in contact with the object is polarized in the slip direction.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the eighth embodiment will be described.

Polarization direction 150 as shown in FIG.
2, the electrode 803a, the electrode 803 as shown in FIG.
The surface of the three-terminal piezoelectric vibrator that is in contact with the object vibrates in the sliding direction by the oscillation circuit 102 having two terminals c. Therefore, for example, a living body has anisotropy of viscoelasticity due to tendons and the like, but the viscoelasticity in the lateral direction can be detected by vibrating in the lateral direction with respect to the object in this manner.

Therefore, in the eighth embodiment, it is possible to detect the viscoelastic characteristic in the lateral direction as the mechanical impedance in the viscoelastic characteristic of the object having anisotropy.

Next explained is a tactile sensor using a piezoelectric vibrator having a three-terminal structure according to the ninth embodiment of the invention.

In the ninth embodiment, the piezoelectric vibrator is brought into contact with the object, and the vibration response from the piezoelectric vibrator due to the pulse application is detected, so that the viscoelastic characteristic and nonlinearity of the object are anisotropic. In the tactile sensor having means for detecting two or three characteristics, the piezoelectric vibrator has the energy trapping electrodes 1 and 2 on one surface and the energy trapping electrode 3 on the other surface. And a means for applying a pulse signal between the electrode 1 and the electrode 3, and a means for detecting a vibration response of the piezoelectric vibrator due to the pulse signal output between the electrode 2 and the electrode 3. Have.

Next, the operation of the tactile sensor using the piezoelectric vibrator having the three-terminal structure of the ninth embodiment will be described.

A pulse signal as shown in FIG. 21A is applied between the terminals 1801 and 1802 of the piezoelectric vibrator 1805 having the energy trapping electrode having the two-terminal structure as shown in FIG. Then, the terminals 1803 and 1804 have the same input and output electrodes.
A waveform in which an input signal as shown in (b) and a vibration waveform according to the characteristics of the piezoelectric vibrator 1805 are superimposed is output. Therefore, in order to detect only the vibration waveform of the piezoelectric vibrator 1805, it is necessary to remove the pulse signal.

On the other hand, the terminals 1601 of the piezoelectric vibrator 803 of the energy trapping electrode having the three-terminal structure as shown in FIG.
When a pulse signal as shown in FIG. 22A is applied between the terminal 1602 and the terminal 1602,
Only a vibration waveform corresponding to the characteristics of the energy trap type three-terminal piezoelectric vibrator 803 as shown in FIG. 22B is output.

This is because vibration occurs between the electrode 803a and the electrode 803c due to the inverse piezoelectric effect due to the pulse signal shown in FIG. 22A, but between the electrode 803a and the electrode 803b, between the electrode 803a and the electrode 803c. Vibration propagated Vibration is occurring. A piezoelectric signal due to the piezoelectric effect corresponding to this vibration is detected between the terminals 1603 and 1604. Therefore, the voltage signal of only the vibration due to the piezoelectric effect is output to the output terminal.

Further, at this time, when ultrasonic waves are generated from the vibration by the energy confinement type three-terminal piezoelectric vibrator 803 and the object is in contact as shown in FIG. 23, the signal at that time is shown in FIG. Like In FIG. 23, 200
Reference numeral 1 is a viscoelastic body, 2002 is an impedance changing section, and 20
Reference numeral 03 is a sensor, 2004 is a transmitted wave, and 2005 is a received wave. Then, the impedance changing unit 2002 reflects the transmission wave 2004 from the sensor 2003,
In 003, the received wave 2005 is detected. FIG. 24 shows the signal at this time. Using this signal, it becomes possible to measure the echo signal by the non-linear elastic part.

FIG. 24 shows an impulse response when there is no load on the energy trap type three-terminal piezoelectric vibrator 803.

When a pulse signal as shown in FIG. 24A is applied to the energy confining three-terminal piezoelectric vibrator 803, the energy confining three-terminal piezoelectric vibrator 803.
Oscillates at a resonance frequency fnoload determined by the shape and dimensions of the energy trapping three-terminal piezoelectric vibrator 803 at this time and an amplitude Vnoload depending on the resonance sharpness Qm as shown in FIG.

FIG. 23 is a schematic diagram for explaining the propagation of ultrasonic waves in a living body.

First, the voltage applied to the energy-trap type three-terminal piezoelectric vibrator 803 has a voltage waveform close to a delta function as shown in FIG. By this delta function voltage application, the energy confining type three-terminal piezoelectric vibrator 803 is vibrationally excited at its resonance frequency, and this vibration vibrates as one vibration system with the object as shown in FIG. Then, a transmission signal waveform 2101 which is an impulse response as shown in FIG.
Propagates through the object 2001 as
When it reaches 002, the vibration is reflected there, and returns to the sensor 2003 as an echo signal 2005 to return to the sensor 2
By vibrating 003, a received signal waveform 2102 is obtained as shown in FIG.

Here, the amplitude in the transmission signal waveform 2101 is V1max, the center frequency is f10, the amplitude in the reception signal waveform 2102 is V2max, and the center frequency is f20. The amplitude Vnoload and the center frequency fnoload when there is no load, the amplitude V1max and the center frequency f10 of the transmission signal waveform 2101, and the reception signal waveform 21
Comparing the amplitude V2max of 02 and the center frequency f10,
Attenuation of amplitude such that Vnoload>V1max> V2max and fnoload
There is a relationship that the frequency>f10> f20 is shifted to the low frequency side. Thus, the amplitude attenuation (Vnoload / V1max) and the frequency shift (f
noload> f10) is related to mechanical impedance. Therefore, the viscoelastic characteristic can be detected by using the transmission signal waveform 2101.

Further, as shown in FIG. 24B, an echo is observed as in the received signal waveform 2102, the amplitude is attenuated (f10> f20 or fnoload> f20), and the center frequency is shifted (V1max> V2max). Or Vnoload> V2m
ax) is related to the nonlinear characteristics of the object. In particular, echoes correspond to discontinuities in acoustic impedance. Therefore, the non-linear characteristic can be detected by using this received signal waveform 2102.

Further, the mechanical impedance of the object is detected from the received voltage waveform, but since it contains not only the information of the object but also the characteristics peculiar to the transducer, it is necessary to separate it. For the separation, the amplitude Vnoload and the center frequency fnoload as shown in FIG. 22 are actually measured, and the separation is performed using this.

Since the difference in the mechanical impedance is reflected in the deviation of the center frequency and the change in the amplitude, the signals are sampled individually, and the FFT and the peak detector are individually applied, and the maximum value of the amplitude and By obtaining the frequency at this time, separation becomes possible, and the nonlinear characteristic can be obtained.

Here, the physical quantities to be detected are arranged again as shown in FIG. In FIG. 26,
f is the frequency, V is the amplitude, t1 is the oscillation time width of the transmission signal waveform 2101, and T is the time until the reception signal waveform 2102 is received. The subscripts 1 and 2 in FIG. 26 correspond to the transmission signal waveform 2101 and the reception signal waveform 2102.

Further, the deviation of the frequency and the change of the maximum amplitude are detected from the transmission signal waveform 2101, and the viscoelastic characteristic is detected from this. Further, the frequency shift, the change in the maximum amplitude, and the time until the echo signal is received are detected from the received signal waveform 2102, and the nonlinear characteristic is detected from this.

Here, for example, a living body has anisotropy in viscoelastic characteristics due to tendons and blood vessels. This anisotropy is shown in FIG.
When the polarization direction 1501 as shown in FIG.
When a pulse as shown in FIG. 24A is applied to the two terminals of the electrode 3a and the electrode 803c, the surface of the energy-trap type three-terminal piezoelectric vibrator 803 that contacts the object vibrates in the thickness direction. Therefore, at that time, a response waveform as shown in FIG. 24B is generated, and from this, the longitudinal viscoelastic characteristics and non-linearity can be detected.

Similarly, when the anisotropy is the polarization direction 1502 as shown in FIG. 18C, the electrode 803a and the electrode 8 are formed.
When a pulse as shown in FIG. 24A is applied to the two terminals of 03c, the surface of the energy trap type three-terminal piezoelectric vibrator 803 in contact with the object vibrates in the slip direction. Therefore, at that time, a response waveform as shown in FIG.
From this, lateral viscoelastic characteristics and non-linearity can be detected.

As described above, the anisotropy is also detected by arranging the polarization directions of the energy confinement type three-terminal piezoelectric vibrator 803 so that the polarization directions are oriented in different directions on the same plane as shown in FIG. It will be possible. For example,
The three-terminal piezoelectric vibrator 3704 polarized in the thickness direction and the three-terminal piezoelectric vibrator 3705 polarized in the sliding direction each have three
A terminal electrode is attached to form an integrated structure.

These are integrated with each other with a groove 3506 interposed therebetween so as not to exert an influence of vibration, each is vibrated, and each signal is processed by a processing circuit 3318 as shown in FIG. As described above, the anisotropy of the object can be detected by the method of integrally using the three-terminal piezoelectric vibrators having the polarization directions different in the thickness direction and the slip direction. As a result, the longitudinal and lateral viscoelastic characteristics of the object, non-linearity,
Anisotropy can be measured.

The signal processing flow at this time is shown in FIG. The drive processing circuit 3318 includes a pulse oscillation circuit 3303 for driving the piezoelectric body 803, a pulse reception circuit 3304 that receives a signal from the electrode 803b, and an impulse response waveform analysis circuit 3308 that analyzes the received signal. Then, the pulse oscillation circuit 3303 and the pulse receiving circuit 3
304, a control circuit 3302 that controls the impulse response waveform analysis circuit 3308, an analysis value storage circuit 3309 that stores the viscoelasticity characteristic value, the nonlinear characteristic value, and anisotropy from the impulse response waveform analysis circuit 3308, and this analysis value storage circuit The analysis value calculation circuit 3310 calculates the value obtained in 3309 into a value related to tactile sense. Then, this calculation result is displayed on the CRT.
Is output to the output circuit 3311 once, and the perceptual data conversion processing circuit 3312 uses the value as tactile data.

Further, the impulse response waveform analysis circuit 3308 has the structure shown in FIG. 28B, and the signal waveform obtained from the pulse receiving circuit 3304 is output from the gate circuit 3314 to the signal waveform shown in FIG. The transmission signal waveform 2101 and the reception signal waveform 2102 shown in are separated. The signal waveform passing through the gate circuit 3314 is a digital F
The FT3315 detects the maximum amplitude and center frequency of the signal waveform, and inputs this value to the analysis value storage circuit 3316.
The above is the operation of the impulse response waveform analysis circuit 3308. The signal processing is performed by the processing circuit as described above.

As described above, in the two-terminal structure shown in FIG. 20, it is necessary to distinguish the input signal and the output signal by the difference signal circuit or the like in order to remove the pulse waveform.
It becomes a factor to enlarge the sensor peripheral circuit. However, the energy trapping electrode has a three-terminal structure as shown in FIG. 19, so that the pulse waveform can be removed without using a difference signal circuit.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the tenth embodiment of the present invention will be described.

FIG. 29 shows the sensor signal 2 on the power line 2219.
It is a figure which shows the principle of the system which overlaps 215.

The sensor circuit 2201 is the pressure sensor 10.
4, a DC signal cutting capacitor 2212, and a circuit 2211 for superimposing a necessary signal from the output from the pressure sensor 104 on the power supply line 2219. The pressure sensor 104 has a configuration similar to that of the pressure sensor 104 shown in FIG. 8 and includes capacitors 1108a and 1108.
b, resistor 1107, inverter 1106, three-terminal electrode 8
A three-terminal piezoelectric vibrator 803 composed of 03a, 803b, and 803c. The oscillation circuit is a 3-terminal piezoelectric vibrator 80.
3 electrodes 803a and 803c, and electrode 803b
Serves as a signal output terminal.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the tenth embodiment will be described.

A constant voltage V is always applied to the power supply line 2219 shown in FIG. In order to transmit a signal using the power supply line 2219, if this signal is a DC signal, it is difficult to distinguish this signal from the constant voltage V, but if it is input to the power supply line 2219 as an AC signal, the identification becomes easy. . For example, the oscillation frequency can be directly superimposed on the power supply line, and the transmission is easy.

The amplitude can be transmitted by once measuring the amplitude with a peak detector or the like and then converting it into a frequency signal according to the amplitude with a VCO or the like. However, it is difficult to simultaneously transmit the oscillation frequency and the amplitude, and it is necessary to output two signals with a certain time difference.

Therefore, a circuit for converting the signal from the pressure sensor 104 into a signal for superimposing on the power supply line 2219 and generating a time difference, a detection / conversion circuit 2211 is used. The signal flow at this time is as follows. (1) A DC voltage is applied to the inverter 1106 and the detection / conversion circuit 2211 using the power supply line 2219. At this time, the detection / conversion circuit 221 is connected by the capacitor 2212.
Since only the differential component of the voltage signal of the power supply line 2219 can be input to the output terminal 1 of 1, the DC voltage does not enter. (2) The power supply line 2219 causes the pressure sensor 104 to oscillate near the resonance frequency of the three-terminal piezoelectric vibrator 803, and has an amplitude corresponding to this resonance resistance. Here, when an object having a viscoelastic property comes into contact with the three-terminal piezoelectric vibrator 803, the resonance resistance and the amplitude change. This amplitude is output with the same waveform from the electrode 803b. However, the phase is shifted. (3) The output signal from the electrode 803b of the three-terminal piezoelectric vibrator 803 is input to the detection / conversion circuit 2211. The detection / conversion circuit 2211 is configured as shown in FIG. 30, the output signal 2501 is divided, the amplitude is detected by a peak detector 2502 for amplitude detection, and the amplitude is converted into a frequency corresponding to the magnitude of the amplitude. The signal is input to the VCO 2503, and its signal is input to the gate circuit 2504.

The signal for the other frequency component is
It is directly input to the gate circuit 2504. At this time,
Since there is processing by detecting the amplitude, the gate circuit 2504
There is a time difference between the signals input to. As shown in FIG. 31, the gate circuit 2504 opens the frequency component gate during the time Tg1 until the signal from the VCO 2503 is input, and outputs the frequency component waveform Wf to the signal line. After that, during time Tg2, the amplitude gate is opened and the amplitude component waveform WVCO is output to the signal line. Therefore, the signal from the gate circuit 2504 becomes 2 within the time T1.
Two signals will be output. As described above, these signals are transmitted on the power supply line 2219. (4) On the other hand, the signal transmitted through the power supply line 2219 is hand-processed for each oscillation frequency and amplitude according to the timing chart shown in FIG. There is a timer circuit which is driven at the same timing as the gate circuit, and the frequency signal received at the timing of time Tg1 can be recognized as the signal of the oscillation frequency, and the frequency signal received at the timing of time Tg2 has the amplitude. It can be recognized as a signal of. By virtue of FM detection of these, the viscoelastic property of the object can be detected.

As described above, according to the tenth embodiment, at least two power supply lines and signal lines are required in the conventional method, but the signal lines are formed by superimposing signals on the power supply lines. Since it can be reduced, the effect is great in fields such as endoscopes and catheters where there are large dimensional constraints.

The detection / conversion circuit 221 shown in FIG.
The peak detector 2502 and VCO 2503 of No. 1 are not necessarily limited to this configuration, and may have another configuration as long as it is a means for detecting the amplitude and converting it into the frequency.

The oscillation circuit of the pressure sensor 104 is not limited to the pierce circuit, and the three-terminal piezoelectric vibrator 8 is used.
Other circuits may be used as long as they are oscillation circuits configured using the equivalent circuit constant of 03.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the eleventh embodiment of the present invention will be described.

FIG. 32 is a diagram showing one transmission system of the output signal of the pressure sensor using the oscillation circuit described in the first embodiment.

First, the pressure sensors are 2401, 402,
2403 and 2404 correspond to this pressure sensor 2401.
Power supply line 240 as a power supply line for driving
Have five.

Details of the pressure sensors 2401 to 2404 are shown in FIG. This FIG. 25 shows a timer circuit 220.
Sensor signal 22 to the power supply line 2219 using
The principle of the method of superimposing 15 is shown. Also, FIG.
3 is a timing chart based on this principle shown in FIG.

The sensor I circuit 2201 is the pressure sensor 1.
04, a timer circuit 2205, capacitors 2212 and 2213 for cutting DC signals, an inverter 1106, a capacitor 2221 for pulse generation, a resistor 2220, and the output from the pressure sensor 104.
It is configured by a circuit 2211 for superimposing on 9.
Of this configuration, sensing start command pulse VP 221
4 is replaced by the input of the timer circuit B 2218 for the pulse 2217 in the sensor II circuit 2202.

The pressure sensor 104 has the same structure as the pressure sensor 104 shown in FIG.
8a, 1108b, resistor 1107, inverter 110
6, a three-terminal piezoelectric vibrator 803 composed of three-terminal electrodes 803a, 803b, 803c. The oscillation circuit is formed by the electrodes 803a and 803c of the three-terminal piezoelectric vibrator,
The electrode 803b serves as a signal output terminal.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the 11th embodiment will be described.

A constant voltage V is always applied to the power supply line 2405 shown in FIG. To transmit a signal through the power supply line 2405, if the signal is a DC signal, it is difficult to distinguish it from the constant voltage V. However, if the AC signal is input to the power supply line 2405, its identification becomes easy. For example, if the above signal is
If input as the C signal, the oscillation frequency can be directly superimposed on the power supply line, and the transmission is easy.

The amplitude can be transmitted by once measuring the amplitude with a peak detector or the like and then converting it into a frequency signal according to the amplitude with a VCO or the like.

Although the signals can be transmitted by the above method, the pressure sensors 2401 to 2401 can be used with the configuration shown in FIG.
Correspondence between 2404 and this sensor output 2401s to 2404s cannot be done at hand. Then, the method using the timer circuits 2205 and 2218 as shown in FIG. 25 makes it possible to associate the pressure sensor with the output. The signal flow at this time is as follows. (1) Each circuit, that is, the timer circuits 2205 and 221
8, D to inverter 2216, detection / conversion circuit 2211
The C voltage is applied using the power supply 2219. At this time, the timer circuit 2 is connected by the capacitors 2213 and 2212.
205 and the output terminal of the detection / conversion circuit 2211,
Since only the differential component of the voltage signal on the power supply line 2219 can be input, no DC voltage is input. (2) The sensing start command pulse 2214 is supplied from the power supply line 2219. (3) The sensing start command pulse 2214 turns on the timer circuit A 2205 that constitutes the sensor I circuit 2201. The timer circuit 2205 outputs the DC voltage V1 during the fixed time T1, and the DC voltage is turned off after the fixed time T1. The inverter circuit 2 is driven by this DC voltage V1.
206 is activated and the pressure sensor 104 oscillates. (4) The pressure sensor 104 oscillates near the resonance frequency of the three-terminal piezoelectric vibrator 803 and has an amplitude corresponding to this resonance resistance. When stress is applied to the three-terminal piezoelectric vibrator 803, the resonance resistance amplitude changes. This amplitude can be output with the same waveform from the electrode 803b. However, the phase is shifted. (5) The output signal from the electrode 803b of the three-terminal piezoelectric vibrator 803 is input to the detection / conversion circuit 2211. The detection / conversion circuit 2211 has a configuration as shown in FIG. 30. The output signal 2501 is divided, the amplitude is detected by a peak detector 2502 for amplitude detection, and the frequency is matched to the magnitude of the amplitude. Convert VCO2503
And the signal is input to the gate circuit 2504.

The signal for the other frequency component is input to the gate circuit 2504 as it is. At this time, there is a time difference between the signals input to the gate circuit 2504 because of the processing by the amplitude detection. As shown in FIG. 31, the gate circuit 2504 opens the frequency component gate and outputs the frequency component waveform Wf to the signal line during the time Tg1 until the signal from the VCO 2503 is input.
After that, during time Tg2, the amplitude gate is opened and the amplitude component waveform WVCO is output. Therefore, two signals from the gate circuit 2504 are output within the time T1. As described above, these signals are transmitted on the power supply line 2219. (6) After time T1, the output of the timer circuit 2205 becomes low level, and the output of the inverter 2216 turns on. This change signal is transmitted to the capacitor 2221 through the differential waveform 22.
17, and the differential waveform 2217 becomes the timer circuit 221.
8 becomes a start command pulse, and the operation of the sensor II circuit 2202 is started. This is sequentially repeated up to the Nth sensor, which corresponds to the Nth sensor 2404 in FIG.
The output of the second timer circuit N is returned to the timer circuit 2205 through the inverter and the capacitor in the same waveform as the sensor start command pulse 2214. This process is repeated. (7) On the other hand, the signal transmitted through the power supply line 2219 is processed at hand for each sensor number according to the timing chart as shown in FIG. There is a timer circuit which is driven at the same timing as the pressure sensor circuit at hand, and the frequency signal received at the timing of time T1 can be recognized as the signal of the sensor I, and oscillation is performed by the timing chart as shown in FIG. There is a timer circuit at hand that drives at the same timing as the gate circuit for processing for each frequency and amplitude, and the frequency signal received at the timing of time Tg1 can be recognized as the oscillation frequency signal, and at the timing of time Tg2. The received frequency signal can be recognized as an amplitude signal. By performing FM detection on these, it is possible to detect the viscoelastic characteristics of the object using a plurality of sensors. Further, the pressure sense applied to the sensor can be detected by performing FM detection on this.

By repeating the above routinely, it is possible to know what kind of pressure sense is applied to which sensor.

As described above, according to the eleventh embodiment, at least two power supply lines and signal lines are required in the conventional system, but the signal lines are formed by superimposing the signals on the power supply lines. Since it can be reduced, its effect is great in places where there are large dimensional constraints such as endoscopes and catheters.

The detection / conversion circuit 221 shown in FIG.
The peak detector 2502 and VCO 2503 of No. 1 are not necessarily limited to this configuration, and may have another configuration as long as it is a means for detecting the amplitude and converting it into the frequency.

The oscillation circuit of the pressure sensor 104 is not limited to the pierce circuit, and the three-terminal piezoelectric vibrator 8 is used.
Other circuits may be used as long as they are oscillation circuits configured using the equivalent circuit constant of 03.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the twelfth embodiment of the present invention will be described.

FIG. 34 is a diagram showing one transmission system of the output signal of the pressure sensor using the oscillation circuit described in the first embodiment.

The structure of the pressure sensor 104 is similar to that of the first embodiment described above. The pressure sensor 104 includes a three-terminal piezoelectric vibrator 103, three-terminal electrodes 103a, 103b, 103.
c, an inverter 1106, a feedback resistor 1107, and capacitors 1108a and 1108b. The transmission of the sensor output is composed of a frequency dividing circuit 2807, an FM modulating circuit 2808, and a transmitting antenna 2809, and a receiving antenna 2810, an FM detecting circuit 2811, and a detecting circuit 28 on the receiving side.
It consists of 12.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the twelfth embodiment will be described.

The frequency of the output signal from the electrode 103b of the three-terminal piezoelectric vibrator 103 is dropped by the frequency dividing circuit 2807,
After being FM-modulated by the FM modulation circuit 2808, it is transmitted through the transmitting antenna 2809. The output signal from the transmitting antenna 2809 is received by the receiving antenna 2810, FM detected by the FM detection circuit 2811, and detected by the detection circuit 2812 as a viscoelastic characteristic. The above is one detection circuit.

In the output, if the center frequency of the pressure sensor 104 and the center frequency for transmission match, the circuit can be simplified.

The oscillation circuit of the pressure sensor 104 is not limited to the pierce circuit, and the three-terminal piezoelectric vibrator 8 is used.
Other circuits may be used as long as they are oscillation circuits configured using the equivalent circuit constant of 03.

As described above, according to the twelfth embodiment, since the transmission line for transmitting the output signal from the pressure sensor 104 is unnecessary, the size of the endoscope, the catheter, etc. is largely restricted. In the above, the effect on the size becomes large.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a thirteenth embodiment of the present invention will be described.

The thirteenth embodiment is a modification of the one transmission method of the output signal when a plurality of pressure sensors using the oscillation circuit described in the first embodiment are used in the twelfth embodiment. FIG.

The structure of the pressure sensor 104 is similar to that of the first embodiment described above. The pressure sensor 104 includes a three-terminal piezoelectric vibrator 103 and three-terminal electrodes 103a, 103b, 103.
c, an inverter 1106, a feedback resistor 1107, and capacitors 1108a and 1108b. The transmission of the sensor output is composed of a frequency dividing circuit 2807, an FM modulating circuit 2808, and a transmitting antenna 2809, and a receiving antenna 2810, an FM detecting circuit 2811, and a detecting circuit 28 on the receiving side.
It consists of 12.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the thirteenth embodiment will be described.

The frequency of the output signal from the electrode 103b of the three-terminal piezoelectric vibrator 103 is reduced by the frequency dividing circuit 2807,
After being FM-modulated by the FM modulation circuit 2808, it is transmitted through the transmitting antenna 2809. The output signal from the transmitting antenna 2809 is received by the receiving antenna 2810, FM detected by the FM detection circuit 2811, and detected by the detection circuit 2812 as a viscoelastic characteristic. The above is one detection circuit.

Then, in FIG. 34, the FM modulation circuit 28
The center frequency of 08 is made different for each pressure sensor so that the receiving side can also detect the signals of the respective center frequencies separately. As a result, a plurality of pressure sensors can be detected wirelessly.

The oscillation circuit of the pressure sensor 104 is not limited to the pierce circuit, and the three-terminal piezoelectric vibrator 8 is used.
Other circuits may be used as long as they are oscillation circuits configured using the equivalent circuit constant of 03.

Next, a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the fourteenth embodiment of the present invention will be described.

As shown in FIG. 35, the three-terminal piezoelectric vibrator 8
03 has three terminals, an electrode 803b and an electrode 803c on the front surface and an electrode 803a on the back surface, and an electrode 803b and an electrode 803c.
Is the equivalent circuit constant L of the three-terminal piezoelectric vibrator 803.
The CR component is used to connect to the circuit 105 that can configure the oscillation circuit, and the oscillation circuit 102 is configured from this. Then, the output terminal 106 that outputs the output signal of the electrode 803b.
The pressure sensor 104 is configured by the detection circuit 108 that detects the sensor signal from the.

Next, the operation of the pressure sensor using the piezoelectric vibrator having the three-terminal structure of the fourteenth embodiment will be described.

In the three-terminal piezoelectric vibrator 803, the electrodes 803b and 803c, which are two terminals of the three terminals, are connected to the circuit 105.
Connected to the electrode 8 of the three-terminal piezoelectric vibrator 803.
03b, the electrode 803c, and the circuit 105 constitute the oscillation circuit 102. At this time, the three-terminal piezoelectric vibrator 803
Becomes a vibrating state depending on the characteristics of the three-terminal piezoelectric vibrator such as impedance characteristics. At this time, the vibration is caused by the electrode 8
On the surface of 03a, vibration 2 having a waveform as shown in FIG.
901 occurs.

When the electrode 803a is used as the contact surface with the object, a structure as shown in FIG. 36 can be considered. FIG. 36 shows
9 is a cross-sectional view of a structure in which a three-terminal piezoelectric vibrator 803 and a circuit board 3002 are connected to each other. FIG. It is provided at the bottom. Three
In the terminal piezoelectric vibrator 803, the electrode 803a is on the upper surface, the electrodes 803b and 803c are on the lower surface, and the surfaces of the electrodes 803b and 803c are not in contact with the circuit board 3002.

With this arrangement, the oscillator circuit 10 shown in FIG.
2 can be configured, and since the electrodes on the same surface are used for the oscillation circuit, connection with the circuit board 3002 including the circuit 105 and the detection circuit 108 becomes easy.

As described above, in the connection between the circuit board 3002 and the three-terminal piezoelectric vibrator 803, the above-mentioned first
In the connection between the electrode 103a and the electrode 103c described in the embodiment, the electrode surfaces are not on the same surface, which makes connection difficult. However, in the fourteenth embodiment, the electrode surfaces are on the same surface, which facilitates connection. Become.

Next, a tactile sensor using a piezoelectric vibrator having a three-terminal structure according to the fifteenth embodiment of the present invention will be described.

As shown in FIG. 27, an electrode 803 is formed on the surface of the three-terminal piezoelectric vibrator 3704 whose polarization direction is the thickness vertical direction.
b, an electrode 803c, and three terminals of an electrode 803a on the back surface, the two terminals of the electrode 803a and the electrode 803c form an oscillation circuit using the equivalent circuit constant LCR component of the three-terminal piezoelectric vibrator as shown in FIG. The oscillator circuit 102 (not shown) is connected to the configurable circuit 105 (not shown).

A pressure sensor 370 including an output terminal 106 (not shown) for outputting an output signal of the electrode 803b and a detection circuit 108 (not shown) for detecting the output signal.
7 and a three-terminal piezoelectric vibrator 37 in which the polarization direction is the slip direction
05 has three terminals, an electrode 803bs and an electrode 803cs, and a back surface, an electrode 803as. Further, the electrode 80
2 terminals of 3as and the electrode 803cs are connected to a circuit 105 (not shown) capable of forming an oscillation circuit using an equivalent circuit constant LCR component of a three-terminal piezoelectric vibrator as shown in FIG.
A pressure sensor 3708 that constitutes the oscillation circuit 102 (not shown) and includes an output terminal 106 that outputs the output signal of the electrode 803bs and a detection circuit 108 that detects the output signal.
Is integrated with a groove 3706.

Next, the operation of the tactile sensor using the piezoelectric vibrator having the three-terminal structure of the 15th embodiment will be described.

In FIG. 27, a three-terminal piezoelectric vibrator 370 is used.
4 is an electrode 803b and an electrode 8 which are two terminals of the three terminals.
When 03c is connected to the circuit 105, the three-terminal piezoelectric vibrator 3
The electrode 803b and the electrode 803c of the circuit 704 and the circuit 105 form the oscillation circuit 102.

At this time, the three-terminal piezoelectric vibrator 3704 is
The above-mentioned three-terminal piezoelectric vibrator 370 such as impedance characteristics
The vibration state depends on the characteristics of No. 4. This vibration vibrates in the vertical direction with respect to the surface of the electrode 803a that contacts the object. The longitudinal viscoelastic characteristic of the object can be detected from the detection signal, and the pressure sensor 3707 is configured.

The three-terminal piezoelectric vibrator 3705 has electrodes 803bs and 803cs, which are two of the three terminals.
Is connected to the circuit 105, the three-terminal piezoelectric vibrator 3705
The electrode 803bs, the electrode 803cs, and the circuit 105 form the oscillation circuit 102. At this time, the three-terminal piezoelectric vibrator 3705 is in a vibration state depending on the characteristics of the three-terminal piezoelectric vibrator 3705 such as impedance characteristics. This vibration vibrates laterally with respect to the surface of the electrode 803a that contacts the object. The lateral viscoelastic characteristic of the object can be detected from the detection signal, and the pressure sensor 3708 is configured.

Then, the pressure sensor 3707 and the pressure sensor 3708 are integrated via a groove 3706 for preventing respective vibrations from propagating.

When the pressure sensor 3701 having such a structure is driven, vertical and horizontal vibrations are generated, and viscoelastic characteristics in both the vertical and horizontal directions can be detected at the same time. This is a tactile sensor because it can detect the anisotropy of the vertical direction and the horizontal direction and can detect the viscoelastic characteristics.

As described above, according to the fifteenth embodiment, the pressure sensor 3707 including the three-terminal piezoelectric vibrator 3704 polarized in the thickness longitudinal direction and the three-terminal piezoelectric vibrator 3705 polarized in the sliding direction are used. By using the pressure sensor that detects only the elastic characteristics of the pressure sensor 3708 that is configured with different polarization, a tactile sensor of a higher order than the pressure sensor can be configured.

The structure shown in FIG. 27 is an example of assembly, and another structure may be used as long as it is a combination capable of detecting the vertical direction and the horizontal direction, such as having four sliding directions.

Next, FIG. 37 (b) is a diagram in which a pressure sensor using a piezoelectric vibrator having a three-terminal structure of the present invention is attached to an endoscope. Reference numeral 3401 denotes an endoscope and 3402 denotes a pressure sensor. By providing the sensor on the side wall of the endoscope in this way, it becomes possible to sense the presence or absence of contact in the body cavity into which the endoscope is inserted, the pressed state, that is, pressure sense information. By feeding this back to the operator of the endoscope, the insertion status of the endoscope can be transmitted to the operator, and the insertion of the endoscope can be facilitated.

FIG. 37 (a) is a diagram in which a manipulator 3404 is equipped with a tactile sensor using a piezoelectric vibrator having a three-terminal structure according to the present invention. In this way, by providing the tactile sensor 3403 just at the portion that touches the ball of the human finger, the condition is very close to the tactile sense of the human finger. For example, in the master slave manipulator, by transmitting this tactile sensation to the operator, the operator can feel as if he / she is actually touching the object without directly touching the object.

Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications and applications are possible within the scope of the gist of the present invention. Here, the summary of the present invention is summarized as follows.

(1) Corresponds to the first embodiment (FIGS. 1 and 3 to 6).

[0208] In a pressure sensor for bringing a vibrator into contact with an object and detecting the viscoelastic characteristic of the object as an electric signal by changing the characteristics of the vibrator, the vibrator is a piezoelectric vibrator, and the piezoelectric vibration The child has three electrodes, a first electrode and a second electrode on one surface and a third electrode on the other surface, and one of the first electrode and the second electrode The two electrodes of the third electrode are connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator to form an oscillation circuit, and the oscillation of the first electrode and the second electrode is performed. A pressure sensor using a piezoelectric vibrator having a three-terminal structure, characterized in that an electrode that does not form a circuit is used as an output terminal.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the oscillation circuit is propagated from the electrode forming the oscillation circuit to the electrode not forming the oscillation circuit. The above-mentioned vibration becomes piezoelectric vibration and charges are generated in the electrodes that are not formed.

Thus, the pressure sensor using the piezoelectric vibrator having the three-terminal structure can detect only the signal in the frequency band Δf by adopting the three-terminal electrode structure, and the signal of the pressure sensor is noisy. It becomes possible to detect it as a signal with less noise.

(2) Corresponds to the second embodiment (FIGS. 1 and 3 to 7).

In (1) above, the pressure sensation using the piezoelectric vibrator having the three-terminal structure is characterized in that the area ratio of the two electrodes of the piezoelectric vibrator forming the oscillation circuit is 0.1 to 1. Sensor.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in the above (1), the ratio of the first electrode to the second electrode of the three-terminal piezoelectric vibrator is 0. It has a structure of 1 to 1. Here, the amplitude of the output signal from the first electrode is determined by the area ratio of the first electrode to the second electrode. If the voltage applied to the second electrode is constant, the generated charge Q is also constant, and it is conceivable to reduce the capacitance C in order to increase the voltage V. Since the electrostatic capacitance C is proportional to the electrode area, the voltage V output from the first electrode increases as the area of the first electrode decreases. Therefore, the output signal is given by the above structural characteristics of the three-terminal piezoelectric vibrator.
Can be amplified.

Thus, the pressure sensor using the piezoelectric vibrator having the three-terminal structure described above can output the output from the three-terminal piezoelectric vibrator constituting the pressure sensor to the sensing circuit without using a circuit such as a charge amplifier. It becomes possible to output as an amplified signal by a certain oscillation circuit.

(3) Corresponds to the third embodiment (FIG. 8).

In the above (1), the piezoelectric vibrator is an energy trap type piezoelectric vibrator. 3
A pressure sensor using a piezoelectric vibrator having a terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in the above (1), the piezoelectric vibrator has the energy trapping type electrode structure, so that the energy directly below the electrode is E1. If the energy of the electrodeless portion is E2, then E1 <E2. Here, since the energy generally moves to the lower side, E1 is always supplied with energy more than E2, and eventually the energy is confined just below the electrode.

Thus, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure can generate vibration at a value close to the theoretical value by adopting the energy confining electrode structure, and has high sensitivity. It is possible to provide a pressure sensor.

(4) Corresponds to the fourth embodiment (FIG. 11).

A pressure sensor using a piezoelectric vibrator having a three-terminal structure according to the above (1), wherein the oscillation circuit is a pierce circuit composed of an element having an inverter function, a resistor and a capacitor.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the piercing circuit is used in the above (1), and the oscillation occurs between the resonance frequency and the anti-resonance frequency. Become.

As a result, the pressure sensor using the piezoelectric vibrator having the above-described three-terminal structure does not require frequency adjustment, and has the effect of facilitating circuit adjustment.

(5) Corresponds to the fifth embodiment (FIG. 14).

In the above (3), adding means for adding the output terminal provided in the oscillation circuit and the output from the electrode which does not form the oscillation circuit among the first electrode and the second electrode is provided. A pressure sensor using a piezoelectric vibrator having a three-terminal structure characterized by being provided.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, when a signal is applied to the two electrodes forming the oscillation circuit in (3) above,
Signals with inverted phases are output from the first electrode and the second electrode. When these signals are added by the adder, the oscillation signal is removed and the pressure sensation signal is doubled and output. Furthermore, even if noise enters the above oscillation circuit,
The signals output from the first electrode and the second electrode have their phases inverted, and thus are removed by the adder.

Thus, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure is strong in noise resistance and has the frequency band Δf shown in FIG. 3 if it is constructed as in the fifth embodiment. It is also possible to remove noise inside.

(6) Corresponds to the sixth embodiment (FIG. 17).

In the above item (5), there is provided a phase shift means for changing the phase of the output from one of the first electrode and the second electrode which does not form an oscillation circuit. A pressure sensor using a piezoelectric vibrator having a three-terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in (5) above, the oscillation circuit of the first electrode and the second electrode is not formed. By passing the output signal from the electrode through the phase shifter, the phase is completely inverted with respect to the output signal from the other electrode.

As a result, the pressure sensor using the piezoelectric vibrator having the three-terminal structure directly outputs the outputs from the first electrode and the second electrode to the adder as shown in (5). In the input configuration, noise may be mixed in the output signal, but by adopting the configuration of the sixth embodiment, noise resistance is strong and noise within the frequency band Δf shown in FIG. 3 is also present. It can be removed.

(7) Corresponds to the seventh embodiment (FIG. 18).

In the above (3), there is provided a three-terminal structure characterized by comprising a thickness direction vibrating means for vibrating the vibration direction of the surface of the piezoelectric vibrator in contact with the object in the thickness direction of the piezoelectric vibrator. A pressure sensor using a piezoelectric vibrator.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in the above (3), when the piezoelectric vibrator has a polarization direction as shown in FIG. The circuit vibrates the surface of the piezoelectric vibrator in contact with the object in the thickness direction of the piezoelectric vibrator.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure can detect the viscoelastic characteristic in the longitudinal direction as the mechanical impedance in the viscoelastic characteristic of the anisotropic object. It is possible.

(8) Corresponds to the eighth embodiment (FIG. 18). In the above (3), a piezoelectric vibration having a three-terminal structure is provided, which comprises a sliding direction vibrating means for vibrating a vibration direction of a surface of the piezoelectric vibrator in contact with an object in a sliding direction of the piezoelectric vibrator. Pressure sensor using a child.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in the above (3), when the piezoelectric vibrator has a polarization direction as shown in FIG. The circuit vibrates the surface of the piezoelectric vibrator in contact with the object in the slip direction of the piezoelectric vibrator.

As a result, the pressure sensor using the piezoelectric vibrator having the three-terminal structure can detect the viscoelastic characteristic in the lateral direction as the mechanical impedance in the viscoelastic characteristic of the anisotropic object. It is possible.

(9) Corresponds to the ninth embodiment (FIGS. 19 to 24). Two or three of the viscoelastic characteristics, non-linearity, and anisotropy of the target object are detected by bringing the piezoelectric vibrator into contact with the target object and detecting the vibration response from the piezoelectric vibrator due to pulse application. In a tactile sensor having a detection means for detecting two characteristics, an energy trapping type first electrode and a second electrode are provided on one surface of the piezoelectric vibrator, and an energy trapping type third electrode is provided on the other surface. Pulse oscillating means having the three electrodes, for applying a pulse signal between any one of the first electrode and the second electrode, and the third electrode; Second above
And a detection means for detecting the vibration response of the piezoelectric vibrator according to the pulse signal output between the other one of the electrodes and the third electrode. Tactile sensor using the piezoelectric vibrator.

According to the tactile sensor using the piezoelectric vibrator having such a three-terminal structure, the polarization directions of the energy-trap type three-terminal piezoelectric vibrator are changed to different directions on the same plane as shown in FIG. Are arranged so that they face each other, and three-terminal electrodes are attached to the three-terminal piezoelectric vibrator polarized in the thickness direction and the three-terminal piezoelectric vibrator polarized in the sliding direction, respectively, and a pressure sensor that vertically vibrates and a vibration sensor that horizontally vibrates. Use the pressure sensor configuration.

As a result, the tactile sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure is different from the target object by the method of integrally using the three-terminal piezoelectric vibrators having the polarization directions different in the thickness direction and the slip direction. It can detect directionality. As a result, the longitudinal and lateral viscoelastic properties of the object,
Non-linearity and anisotropy can be measured. Further, in the piezoelectric vibrator having the two-terminal structure as shown in FIG. 20, it is necessary to distinguish the input signal and the output signal by a difference signal circuit or the like in order to remove the pulse waveform, which becomes a factor of enlarging the sensor peripheral circuit. . However, by adopting a three-terminal structure in the energy trapping electrode, it becomes possible to remove the pulse waveform without using the difference signal circuit.

(10) Corresponds to the tenth embodiment (FIG. 29).

In the above (1), the viscoelastic characteristic of the object is detected as an electric signal from the output from the electrode which does not form the oscillation circuit among the first electrode and the second electrode, A transmission means for transmitting the electric signal by superimposing it on the power supply line of the pressure sensor and transmitting the electric signal.
A pressure sensor using a piezoelectric vibrator having a terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the amplitude of the electric signal detected by the pressure sensor is once measured by a peak detector or the like, and then the VCO or the like. Is converted into a frequency signal according to the amplitude. However, it is difficult to simultaneously transmit the oscillation frequency and the amplitude, and it is necessary to output two signals with a certain time difference. Therefore, the electric signal is converted into a signal to be superimposed on the power supply line by the detection / conversion circuit,
In addition, it is converted into a signal having the above time difference.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure requires at least two power lines and signal lines in the conventional method. Since it is possible to reduce the number of signal lines, the effect is great in a field where there are large dimensional constraints such as an endoscope and a catheter.

(11) Eleventh embodiment (FIGS. 25 and 30)
Corresponding to Figure 33). In (10) above, a piezoelectric device having a three-terminal structure, characterized in that a plurality of the pressure sensors are provided, and a timer circuit that associates each pressure sensor with the output of each pressure sensor is provided. Pressure sensor using a vibrator.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the signal can be transmitted by the above (10), but with the configuration shown in FIG. 2404 and this sensor output 240
I cannot handle 1s to 2404s at hand. Therefore, the pressure sensor is associated with the output by the method using the timer circuits 2205 and 2218 as shown in FIG.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure requires at least two power supply lines and signal lines in the conventional method. Since it is possible to reduce the number of signal lines, the effect is great in a field where there are large dimensional constraints such as an endoscope and a catheter.

(12) Corresponds to the twelfth embodiment (FIG. 34).

In the above (1), the viscoelastic characteristic of the object is detected as an electric signal from the output from the electrode which does not form the oscillation circuit among the first electrode and the second electrode, The electric signal is FM-modulated and then transmitted, and a transmitting unit is provided, a receiving unit that receives the transmitted signal and performs FM detection, and a detection unit that detects a viscoelastic characteristic signal from the FM-detected signal. A pressure sensor using a piezoelectric vibrator having a three-terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the frequency of the output signal from the electrode of the above-mentioned three-terminal piezoelectric vibrator is dropped by the frequency dividing circuit, and F
M modulation circuit After being FM-modulated, it is transmitted through a transmitting antenna. The output signal from the transmitting antenna is received by the receiving antenna and FM-detected by the FM detection circuit,
It is detected as a viscoelastic characteristic by the detection circuit.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure does not require a transmission line for transmitting the output signal from the pressure sensor, so that the size of the endoscope, catheter, etc. is restricted. , The effect on the size is large.

(13) Corresponds to the thirteenth embodiment (FIG. 34).

A plurality of pressure sensors using the piezoelectric vibrator having the three-terminal structure described in the above (12) are provided, and a plurality of center frequencies are included in the transmitted and received propagating waves.
A pressure sensor using a piezoelectric vibrator having a terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, in the above (12),
As shown in FIG. 34, the center frequency of the FM modulation circuit is made different for each pressure sensor, and the receiving side can also detect the signal of each center frequency separately for each pressure sensor. Therefore, each of the plurality of pressure sensors can be detected wirelessly.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure does not require a transmission line for transmitting the output signal from the pressure sensor, so that the size of the endoscope, catheter, etc. is restricted. , The effect on the size is large.

(14) Fourteenth Embodiment (FIGS. 35 and 36)
Corresponding to.

[0257] In a pressure sensor having a detection means for bringing a vibrator into contact with an object and detecting the viscoelastic characteristic of the object as an electric signal by changing the characteristics of the vibrator, the vibrator is a piezoelectric vibrator. , The first electrode and the second electrode on one surface of the piezoelectric vibrator, and the three electrodes of the third electrode on the other surface, and the first electrode and the second electrode.
Is connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator to form an oscillation circuit. A pressure sensor using the piezoelectric vibrator having a three-terminal structure.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the first electrode and the second electrode on the same plane use the equivalent circuit constant of the piezoelectric vibrator. It is connected to a circuit that oscillates to form an oscillation circuit. As a result, in the pressure sensor using the piezoelectric vibrator having the above-described three-terminal structure, the electrode surface for connecting the oscillation circuit is not on the same surface in the above-described first embodiment, so connection is difficult, but with this configuration. Connection is facilitated because the electrode surfaces are on the same surface.

(15) Corresponds to the fifteenth embodiment (FIG. 27).
In the above (1), a thickness direction vibrating unit that vibrates the vibration direction of the surface of the piezoelectric vibrator that contacts an object in the thickness direction of the piezoelectric vibrator, and the vibration direction of the surface of the piezoelectric vibrator is the piezoelectric vibration. A tactile sensor using a pressure sensor using a piezoelectric vibrator having a three-terminal structure, comprising: a sliding direction vibrating unit that vibrates in a sliding direction of a child.

According to the pressure sensor using the piezoelectric vibrator having such a three-terminal structure, the surface of the electrode contacting the object and the surface of the electrode contacting the object are oscillated in the vertical direction. On the other hand, a pressure sensor that vibrates in the lateral direction is integrally formed via a groove so that each vibration does not propagate. When driving the pressure sensor with such a configuration,
Vibrations in the vertical and horizontal directions occur, and viscoelastic characteristics in both the vertical and horizontal directions can be detected at the same time.

As a result, the pressure sensor using the piezoelectric vibrator having the above-mentioned three-terminal structure is polarized in the thickness longitudinal direction.
By using a pressure sensor composed of terminal piezoelectric vibrators and a pressure sensor that detects only the elastic characteristics of a pressure sensor composed of three-terminal piezoelectric vibrators polarized in the slip direction, which are differently polarized, It becomes possible to configure a high-order tactile sensor.

[0262]

As described above, according to the present invention, there is provided a pressure and tactile sensor using a piezoelectric vibrator having a strong noise resistance, a high resolution, and a three-terminal structure which can be downsized. It becomes possible to provide.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a first embodiment.

FIG. 2 is a diagram showing a configuration of an oscillation circuit using a conventional two-terminal piezoelectric vibrator.

FIG. 3 is a diagram showing a frequency band of an output signal from a pressure sensor.

FIG. 4 is a diagram showing an output signal output from an output terminal 106.

FIG. 5 is a diagram showing a Mason equivalent circuit of the piezoelectric vibrator.

FIG. 6 is a diagram showing an equivalent circuit near the resonance frequency of the piezoelectric vibrator.

FIG. 7 is a diagram showing an electrode area ratio of a piezoelectric vibrator and an amplitude characteristic of an output signal.

FIG. 8 is a diagram showing an energy trap type three-terminal piezoelectric vibrator and a pressure sensor according to a third embodiment.

FIG. 9 is a diagram showing a structure of a conventional two-terminal piezoelectric vibrator.

FIG. 10 is a diagram showing a structure of an energy trap type two-terminal piezoelectric vibrator.

FIG. 11 is a diagram showing a configuration of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a fourth embodiment.

FIG. 12 is a block diagram illustrating a flow of detection processing according to a fourth embodiment.

FIG. 13 is a block diagram showing a flow of processing in a comparator 3204.

FIG. 14 is a diagram showing a configuration of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a fifth embodiment.

FIG. 15 is a diagram showing an equivalent circuit of an energy confinement type three-terminal piezoelectric vibrator.

FIG. 16 is a diagram summarizing output signals in the fifth embodiment.

FIG. 17 is a diagram showing the configuration of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a sixth embodiment.

FIG. 18 is a diagram showing the structure of a piezoelectric vibrator having a three-terminal structure according to a seventh embodiment.

FIG. 19 is a diagram for explaining the operation of the energy trap type piezoelectric vibrator having the three-terminal structure according to the ninth embodiment.

FIG. 20 is a diagram for explaining the principle of a two-terminal piezoelectric vibrator.

FIG. 21 is a diagram showing an output signal of a two-terminal piezoelectric vibrator.

FIG. 22 is a diagram showing an output signal of a three-terminal piezoelectric vibrator.

FIG. 23 is a schematic diagram showing the propagation of ultrasonic waves in a living body.

FIG. 24 is a diagram showing input / output signals in the tactile sensor.

FIG. 25 is a diagram showing a power line superimposing sensor signal transmission circuit.

FIG. 26 is a diagram summarizing physical quantities detected by a tactile sensor.

FIG. 27 is a view showing an example of assembling different-direction polarization of a piezoelectric vibrator.

FIG. 28 is a diagram showing a signal processing flow of the tactile sensor.

FIG. 29 is a diagram showing a power supply line superimposed sensor signal transmission circuit (single unit).

FIG. 30 is a diagram showing a power supply line superposition type detection / conversion circuit.

FIG. 31 is a timing chart of a power line superimposing detection / conversion circuit.

FIG. 32 is a diagram showing a power line superposition type conceptual diagram.

FIG. 33 is a timing chart of power line superimposed sensor signal transmission.

FIG. 34 is a diagram showing a wireless sensor signal transmission circuit.

FIG. 35 is a diagram showing the structure of a pressure sensor using a piezoelectric vibrator having a three-terminal structure according to a fourteenth embodiment.

FIG. 36 is a diagram showing a configuration of a three-terminal piezoelectric vibrator and a circuit board.

FIG. 37 shows an example in which a pressure sensor and a tactile sensor are attached to an endoscope and a manipulator.

FIG. 38 is a diagram showing a circuit diagram of a crystal oscillator gas sensor of a conventional example and an equivalent circuit in the vicinity of the resonance frequency of the crystal oscillator on this circuit diagram.

FIG. 39 is a diagram showing a configuration of a conventional tactile sensor.

[Explanation of symbols]

101 ... Pressure information, 102 ... Oscillation circuit, 103 ... 3-terminal piezoelectric vibrator, 103a, 103b, 103c ... Electrode, 1
04 ... Pressure sensor, 105 ... Circuit, 106, 107 ... Output terminal, 108 ... Detection circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H03H 9/17 H // A61B 1/00 300 D

Claims (3)

[Claims] 1. A pressure sensor for bringing a vibrator into contact with an object to detect viscoelastic characteristics of the object as an electric signal by changing characteristics of the vibrator, wherein the vibrator is a piezoelectric vibrator. The piezoelectric vibrator has three electrodes, a first electrode and a second electrode on one surface and a third electrode on the other surface, and either one of the first electrode and the second electrode One of the first electrode and the second electrode is connected to a circuit that oscillates using the equivalent circuit constant of the piezoelectric vibrator to form an oscillation circuit. A pressure sensor using a piezoelectric vibrator having a three-terminal structure, characterized in that an electrode not forming the oscillation circuit is used as an output terminal. 2. A viscoelastic property, a non-linearity, and anisotropy among the object are obtained by bringing the object into contact with a piezoelectric vibrator and detecting a vibration response from the piezoelectric vibrator by applying a pulse. In a tactile sensor that detects two or three characteristics, an energy trap type first sensor is provided on one surface of the piezoelectric vibrator.
Of the first electrode and the second electrode and the third electrode of the energy trapping type third electrode on the other surface, and one of the first electrode and the second electrode and the third electrode. Pulse applying means for applying a pulse signal between the electrodes, the first electrode and the second electrode by the applied pulse signal
A piezoelectric vibration having a three-terminal structure, comprising: a detection unit that detects a vibration response of the piezoelectric vibrator output between the other one of the electrodes and the third electrode. Tactile sensor using a child. 3. A pressure sensor for bringing a vibrator into contact with an object and detecting the viscoelastic characteristic of the object as an electric signal by changing the characteristic of the vibrator, wherein the vibrator is a piezoelectric vibrator, and The piezoelectric vibrator has three electrodes, a first electrode and a second electrode on one surface and a third electrode on the other surface, and the first electrode and the second electrode are connected to the piezoelectric vibrator. 3 is characterized in that it is connected to a circuit that oscillates by using the equivalent circuit constant of No. 1 to form an oscillation circuit, and one of the first electrode and the second electrode is used as an output terminal. A pressure sensor using a piezoelectric vibrator having a terminal structure.