JPH0989746A - Sensor and monolithic piezoelectric vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor by which the resonance frequency and the resonance resistance of a piezoelectric vibrator can be found simultaneously so as to be separated. SOLUTION: A sensor is provided with an input terminal 95 to which input signals having different frequencies according to the passage of time are input, with a transistor 89 which amplifies an input signal to be input from the input terminal 95 and with a piezoelectric vibrator 88 which is connected in parallel with an emitter resistance 90 at the transistor 89 and which is resonated with reference to the specific frequency of the input signal. On the basis of the output of the transistor 89 at a time when the output signal from the input terminal 95 is input and the piezoelectric vibrator 88 is resonated, the resonance frequency and the resonance resistance of the piezoelectric vibrator 88 are detected simultaneously so as to be separated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor using a monolithic piezoelectric vibrator.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 2-290529 shows an example of a sensor using a piezoelectric vibrator, and FIG. 12 shows the structure of such a sensor. In the figure, the piezoelectric element 3 and the amplifier 16 constitute a self-excited oscillation circuit 8, and the sensor head 1, the amplifier 16, and the frequency counter 9 are included.
a, frequency-voltage converter 17, A / D converter 1
Reference numeral 8 constitutes a self-excited oscillation frequency change detection circuit. In such a configuration, a change in the oscillation frequency when the sensor head 1 comes into contact with an object is detected by the frequency counter 9a, converted into a level output by the frequency-voltage converter 17, and this level output is further converted by the AD converter 18. And then A
-D converted and output as information indicating the hardness value.

Further, the oscillator 12a, the sensor head 1, the amplifier 16, the rectifying circuit 14a, the smoothing circuit 14b, and the A / D converter 18 constitute a level change detecting circuit. In such a configuration, when the sensor head 1 comes into contact with an object, the output level changes due to the AC voltage applied by the oscillator 12a. This change in output level is caused by the rectifier circuit 14a.
Is rectified, smoothed by the smoothing circuit 14b, A / D converted by the A / D converter 18, and output as information indicating the hardness value.

The above-mentioned two circuits, that is, the self-excited oscillation frequency change detection circuit and the output level change detection circuit are switched by three kinds of switches SW1, SW2, SW3 operated in conjunction with each other by the analog switch circuit 19. The analog switch circuit 19 is switched by the timer 20 at predetermined time intervals. Then, the arithmetic circuit 21 uses the timer 20.
In addition to the drive control of, the hardness information is obtained based on the two hardness information output from each of the above circuits.

As described above, the above-mentioned sensor has three switches SW1, SW2, and SW3 for changing the self-oscillation frequency (resonance frequency) and the output level, that is, the resonance resistance when an object contacts the sensor head 1. Is obtained by switching.

[0006]

However, in the sensor having the above-mentioned structure, the resonance frequency and the resonance resistance of the piezoelectric vibrator cannot be separately measured at the same time. The present invention has been made in view of such a problem, and an object thereof is to separately detect the resonance frequency and the resonance resistance of the piezoelectric vibrator at the same time to detect the elastic characteristics and the viscous characteristics of the load. The purpose is to provide a sensor that seeks the Another object of the present invention is to provide a monolithic piezoelectric vibrator having a small size and improved measurement reliability.

[0007]

In order to achieve the above object, the sensor of the present invention has an input section for inputting input signals having different frequencies according to the passage of time, and an input section from this input section. An amplifying means for amplifying the input signal, a piezoelectric vibrator provided with respect to the amplifying means, and resonating with respect to a specific frequency of the input signal; Signal processing means for separating and simultaneously detecting the resonance frequency and the resonance resistance of the piezoelectric vibrator based on the output of the amplifying means when resonating is provided.

That is, the sensor of the present invention inputs an input signal having a different frequency according to the passage of time from the input section, and amplifies the input signal by the amplifying means. And
The resonance frequency and the resonance resistance of the piezoelectric vibrator are separately detected at the same time based on the output of the amplifying unit when the piezoelectric vibrator resonating with respect to a specific frequency of the input signal resonates. .

Further, the present invention provides a monolithic piezoelectric vibrator in which a plurality of piezoelectric vibrators are formed on the same piezoelectric plate,
The first and second electrodes are arranged in parallel on the first surface of the piezoelectric vibrator, and the first, second, and third electrodes are arranged in parallel on the second surface of the piezoelectric vibrator. The first electrode provided on the first surface and the first electrode provided on the second surface constitute an S-mode piezoelectric vibrator, and the first electrode is provided on the first surface. An A-mode piezoelectric vibrator is configured by the provided second electrode and the second and third electrodes provided on the second surface.

That is, in the monolithic piezoelectric vibrator of the present invention, the first and second electrodes are arranged in parallel on the first surface of the plurality of piezoelectric vibrators, and the second electrode of the piezoelectric vibrator is arranged. By arranging the first, second, and third electrodes in parallel on the first surface, the first electrode provided on the first surface is provided.
S-mode piezoelectric vibrator composed of the first electrode provided on the second surface, the second electrode provided on the first surface, and the second electrode provided on the second surface. It has two detection modes, each of which is composed of an A-mode piezoelectric vibrator composed of the provided second and third electrodes.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the present embodiment, the change in impedance of the piezoelectric vibrator is detected simultaneously by separating the change in resonance frequency and the change in resonance resistance. And a viscous characteristic.

FIG. 1 is a diagram showing the configuration of the tactile sensor circuit 5 and its periphery according to the first embodiment. In FIG.
Reference numeral 88 denotes a piezoelectric vibrator as a tactile sensor, and a transistor 8
9 is connected in parallel to the emitter resistor 90. A wiring 96 for supplying a DC bias voltage is connected to the base input of the transistor 89 by a capacitor 96 and DC bias resistors Rb1 (92) and Rb2 (93). A load resistance RL91 is connected to the collector portion of the transistor 89, and a collector voltage is supplied via the load resistance RL91. The collector output is the capacitor 9
The DC component is cut off via 7 and further converted into a DC pulse signal through the diode 107 and output to the terminal 98. Then, the signal is transmitted to the control circuit block section described later through the tactile sensor signal transmission line 3 connected to the terminal 98. Reference numeral 95 denotes an input terminal for inputting a high frequency pulse signal, which is connected to the signal transmission line 2, and a DC power supply voltage supply terminal 150 is connected to the signal transmission line 2 via the rectifier circuit 109.

FIG. 2 is a block diagram of a control circuit for controlling the tactile sensor circuit 5 described above. In FIG. 2, 110
Is a rectangular wave generator that outputs a rectangular wave 112, 111 is a sawtooth wave generator that generates an intermittent sawtooth wave 102 in synchronization with the rectangular wave 112, and 114 is a buffer circuit. Reference numeral 115 denotes an FM modulation circuit that changes the frequency around a specific frequency fi according to the output voltage value of the buffer circuit 114, and its output waveform is a high frequency pulse train signal composed of high frequency pulses that change the same frequency.

FIG. 3 is a diagram showing the structure of an FM modulation circuit for generating such a high-frequency pulse train signal, which is composed of a Colpitts oscillation circuit having a piezoelectric vibrator 5001, a variable capacitance diode 5002 and capacitors 5003 and 5004 as constituent elements. Has been done. 5005 is a power supply terminal, 5006 is a transistor, 5007 is an emitter resistance, 5008 is a DC blocking capacitor, 5009 is an output terminal, 5010, 5
011 is a DC bias resistor, 5012 is an input terminal, 50
Reference numeral 13 denotes an input resistance, and the high frequency pulse train signal is configured to be input from the output terminal 5009 to the terminal 95 of the tactile sensor circuit 5 via the signal transmission line 2.

Further, the control circuit of FIG. 2 also includes a signal processing unit for the tactile sensor pulse train signal Ssens (121). This signal processing unit uses the tactile sensor pulse train signal 121.
A peak detector 131 for detecting the pulse peak value of
An AD converter 133 that converts the output of the peak detector 131 into a digital signal, a counter circuit 129 that counts the time from the rising time T1 of the rectangular wave obtained by amplifying the same pulse waveform by the amplifier 119 to the peak time of the pulse train signal, and counts the time A clock signal generator 113, a decoder 130 for converting the BCD output of the counter circuit 129 into an input signal of the arithmetic circuit 134,
The presenting device 13 performs arithmetic processing based on the outputs of these two systems.
6 is composed of various circuits of an arithmetic circuit 134 which outputs an input signal to the circuit 6.

FIG. 4A is a diagram showing the waveform of a high frequency pulse signal input to the input terminal 95 of the tactile sensor circuit 5. As shown in the figure, the amplitude is constant from time T1 (85) when the high-frequency pulse rises to time T2 (86) when the high-frequency pulse rises, and as shown in FIG.
It is a signal that continuously changes from −Δfi to fi + Δfi.

The detection principle of the tactile sensor circuit 5 described above will be described below. 5 and 6, the piezoelectric vibrator 88
Is the resonance resistance ZrA as shown in 99 when there is no load (state A).
Is small, the anti-resonance resistance ZaA is large, and a large impedance characteristic of Qm having the resonance frequency frA and the anti-resonance frequency faA is shown. When a load such as 100, 101 in FIG. 5 or B to E in FIG. 6 is applied to this, a resonance resistance ZrB and a B load impedance characteristic 100 having a resonance frequency frB depending on the content of the load, and The C load impedance characteristic 101 having the resonance resistance ZrC and the resonance frequency frC is exhibited. Other load states D, E
Similarly for ZrD, ZaD, frD, faD and ZrE, Za
An impedance characteristic having E, frE, and faE is shown.

Such a change in resonance frequency ΔfrB = frA−
frB, ΔfrC = frA−frC, ... And change in antiresonance frequency Δ
faB = faA−faB, ΔfaC = faA−faC, ..., Or change in resonance resistance ΔZrB = ZrA−ZrB, ΔZrC = ZrC−Zr
C, ..., Change in anti-resonance resistance ΔZaB = ZaA−ZaB, ΔZaC
= ZaC-ZaC, ... is related to the real part and the imaginary part of the mechanical impedance of the viscoelastic body when the load is a viscoelastic body object, and further calculated from these two characteristics Δf and ΔZr. It becomes possible to express elastic modulus and viscosity separately. When expressed as one characteristic by taking one of these two characteristics Δf and ΔZr, or taking the square root of the sum of the squares of both, it can be used as a pressure sensor, that is, a sensor that detects the pressing force when the sensor contacts a viscoelastic object. Can be easily guessed.

From the above impedance characteristics, the impedance of the piezoelectric vibrator 88 changes when a load is applied to a high frequency signal having a constant frequency and amplitude, but this change amount is, as can be seen from the above description, the resonance frequency. It can be seen that it is due to the effect of both the change due to the change in the resonance resistance and the change due to the change in the resonance resistance. When a change in impedance due to both of these effects occurs due to the application of a load, a high frequency pulse signal having an amplitude Vin and a frequency fin as shown in FIG. 4A is input to the terminal 95 of the circuit shown in FIG. , The output terminal 97 of the capacitor Cc2 (97) has an amplitude Vout = Vin × RL / (RE | Z) and a frequency fout = f.
A high frequency amplified output of in is obtained.

Since Vout when a load is applied is smaller than that when no load is applied according to the above equation in response to an increase in the impedance of the piezoelectric vibrator 88 due to application of a load, the piezoelectric vibration is detected by detecting this change in Vout. The change in the impedance Z of the child 88 is known, and the state of load application can be determined from the change in the impedance Z.

Here, the amplitude is constant and the input frequency f
in is represented by the straight line indicated by 103 in FIG. 7 from time T1 to T
When it is monotonically increased from fi-Δfi to fi + Δfi over 2, if the piezoelectric vibrator 88 is in an unloaded state, the fin is corresponding to the resonance resistance Zr and the impedance characteristic 99 of the resonance frequency fr as shown in FIG. At time T0 when it becomes equal to fr, a high-frequency pulse signal of maximum amplitude is output, and the signal output to the terminal 98 after passing through the capacitor 97 and the diode 107 is the DC pulse signal having the peak value V shown at 104 in FIG. Become.

Further, when the A load shown in FIG. 5 is applied to the piezoelectric vibrator 88, and the impedance characteristic 100 of the resonance resistance Zr 'and the resonance frequency fr' is exhibited,
Corresponding to this, the peak voltage of the output of the terminal 98 becomes smaller corresponding to the resonance resistance increasing to Zr ',
The time at which the peak voltage is indicated is also shifted to time T'when the applied frequency fin becomes fr '. Similarly, when the B load in FIG. 5 is applied to the piezoelectric vibrator 88 and the impedance characteristic 101 changes, the applied frequency fin shifts to the time T ″ when the applied frequency fin becomes fr ″.

Next, a method of detecting the shift amount and the peak value will be described with reference to FIG. First, the rectangular wave 112 obtained by the rectangular wave generator 110 is converted into the sawtooth wave generator 11
It is input to 1 and converted into an intermittent sawtooth wave 102. The intermittent sawtooth wave 102 is input to the buffer circuit 114, and its output signal is input to the FM modulator 115. Then, the output from this FM modulator is frequency f from time T1 to time T2.
A pulse train signal composed of signals as shown in FIGS. 4A and 4B is obtained by changing from fi-Δfi to fi + Δfi around i. At the moment when the high frequency pulse signal is present, fi-Δf
When a high frequency pulse changing from i to fi + Δfi is input to the tactile sensor circuit 5 of FIG. 1, a DC pulse signal is output to the output terminal 98 of the tactile sensor circuit 5 including the piezoelectric vibrator 88 having a resonance frequency of fi. . When the load state changes at other moments, the tactile sensor circuit 5 outputs DC pulse signals corresponding to the respective timings, so integrating all the moments results in a tactile sensor pulse train signal 121 as shown in FIG. .

After this signal is branched, one of them is shown in FIG.
Amplifier (comparator) of the control circuit block shown in
19 is input. The DC pulse signal is converted into a rectangular pulse wave signal by the comparator 119, and the counter circuit 129 counts the time from the time T1 to the rising or falling time of this rectangular wave. The change in the calculated value due to the application of the load, that is, the change in the resonance frequency is calculated from the count number of the clock signal from the clock signal generator 113.

The other one is input to the peak detector 131 of the control circuit block shown in FIG. 2 and the peak value is detected. Then, the detection signal is converted into a digital signal by the AD converter 133, processed by the arithmetic circuit 134 together with the count value, and drives the presentation device 136.

According to the above-described first embodiment, the elastic modulus and the viscosity coefficient of the viscoelastic object can be separated and simultaneously detected. The second embodiment of the present invention will be described below. In the tactile sensor using the Colpitts circuit, if the resonance resistance of the piezoelectric vibrator of the Colpitts circuit is large, it is difficult to oscillate and the dynamic range of the sensor becomes extremely poor. On the other hand, it is preferable that the electrodes of the piezoelectric vibrator have the electric wiring terminals on the same surface side in consideration of the ease of wiring and the necessity of downsizing. Vibration due to such driving is called A-mode thickness longitudinal vibration and exhibits good impedance characteristics, but it is difficult to obtain a stable oscillation output of the Colpitts oscillator because of high resonance resistance. The second embodiment solves such a problem.

The structure of the second embodiment differs from that of the first embodiment in that the structure of the piezoelectric vibrator 88, the emitter resistance 90, and the load resistance (collector resistance) 91 in the structure of the tactile sensor circuit shown in FIG. It is a value.

The configuration of this embodiment will be described below with reference to FIG.
A description will be given using (a), (b), and (c). The piezoelectric vibrator (FIG. 8A) used in the first embodiment is connected in parallel to the emitter resistor 90 and is called an S-mode piezoelectric vibrator. On the other hand, as shown in FIG. 8B, the electrode of the piezoelectric vibrator 138 is provided with the common electrode 141 on the side in contact with the object, and the electrode 139, which is divided into two, on the opposite surface. 140 is provided. Such a piezoelectric vibrator is called an A-mode piezoelectric vibrator. Common electrode 14
1 has an area about the sum of the area of the divided electrode 139 and the area of the divided electrode 140, and does not require any wiring. Therefore, the surface on the common electrode 141 side has no unevenness, and it becomes easier to form an elastic member, a protrusion for realizing a good contact state with an object, or the like on the surface.

As shown in FIG. 8 (c), A having such a structure is used.
The impedance characteristic of the mode-thickness longitudinal piezoelectric vibrator is generally the impedance characteristic 144 of the S-mode thickness-longitudinal piezoelectric vibrator.
An impedance characteristic 143 having a larger resonance resistance than that of the above is shown.

Therefore, in order to obtain the same sensor sensitivity as that of the previous embodiment, the emitter resistance 142 and the load resistance (collector resistance 9) shown in FIG.
1) needs to be increased. At the same time, as shown in FIG. 8C, the impedance 143 of the A-mode thickness longitudinal piezoelectric vibrator has a resonance frequency also shifted to the high frequency side, so that the center frequency of the high frequency pulse train signal is set to be equal to fr. The other configurations and waveforms are exactly the same as those in the first embodiment, and will be omitted.

According to the second embodiment described above, since the one surface of the piezoelectric vibrator has no unevenness at all, the surface on the common electrode side has no unevenness, and the elastic member and the object It becomes easy to form a protrusion or the like for achieving a good contact state with.

The third embodiment of the present invention will be described below.
As described above, when a viscoelastic object is used as a load, changes in the resonance frequency fr and the resonance resistance Zr of a plurality of piezoelectric vibrators are detected, and the results are used to derive a viscosity coefficient and an elastic coefficient. Has been described. However, when the viscoelastic object is used as a load, it actually changes not only the resonance frequency fr and the resonance resistance Zr but also the anti-resonance frequency fa and the anti-resonance resistance Za as shown in FIG. The purpose of this embodiment is to further improve the sensitivity by using these changes in the anti-resonance frequency fa and the anti-resonance resistance Za.

FIG. 9 is a diagram showing the configuration of the third embodiment. Reference numeral 2001 denotes a monolithic piezoelectric vibrator that serves as a tactile sensor, and includes an A-mode piezoelectric vibrator 2002 connected in parallel to an emitter resistor 2007 of a transistor 2006 and two capacitors 2004, 2005 and S whose one end is connected to the base of the transistor 2006. The mode piezoelectric vibrator 2003 is composed of circuit elements connected in a T shape. In the figure, the piezoelectric vibrator 2002 of the above two modes,
Although the 2003 is integrated, it may be configured as a separate body.

The base of the transistor 2006 is further provided with DC bias resistors Rb1 2011 and Rb2 201.
2 is connected to determine the DC operating point of the transistor 2006. A load resistor 2008 is connected to the collector of the transistor 2006, and the terminal 2015 is connected to the signal line 2 via the rectifier circuit 2030. A DC blocking capacitor 2009, a diode 2010 for converting to a DC pulse signal, and a terminal 2014 for transmitting the output to the sensor signal transmission line 3 are provided in the collector section.
Is provided.

A terminal 2013 is provided at the other end of the T-shaped circuit element and is connected to the signal line 2 so that a high frequency pulse signal can be input. The T
The last end of the V-shaped circuit element is the A-mode piezoelectric vibrator 2
Both terminals (B) of 002 are grounded together (20
16). The rectifier circuit 2030 described above is connected to the address signal line 2 by using a rectifier circuit equivalent to that shown in FIG.

The resonance frequency frA of the A-mode piezoelectric vibrator 2002 and the anti-resonance frequency fas of the S-mode piezoelectric vibrator 2003 are made to be substantially the same in design such as electrode size and arrangement.

FIG. 10 shows the above-mentioned 2 which is a tactile sensor element.
A cross-sectional view of a monolithic piezoelectric vibrator 2001 in which a type of piezoelectric vibrator and two capacitors are integrated is shown. A method of manufacturing such a monolithic piezoelectric vibrator 2001 will be described below. First, the region 2018 is polarized by using a preliminary electrode (not shown) capable of removing the PZT thin piece later, and the region 2019 is left unpolarized.

After polarization, the preliminary electrode is removed and the formal electrode A,
B, C, D, E, and F are formed by means of vacuum evaporation, sputtering, or the like, and pattern formation is performed. Incidentally, when utilizing a piezoelectric vibrator in which a piezoelectric thick film such as a PZT thick film is formed on a substrate, the means of the spare electrode cannot be used. Therefore, electrodes A, B, C, and D are formed in advance on the surface of the substrate, a PZT thick film is formed by the jet printing system method (JPS method) already disclosed by the present inventors, and after heat treatment, The upper electrodes E and F are formed by a normal method, and then the electrodes E and F are conductively connected to be one polarization terminal, and the lower electrodes A and B are conductively connected to the other polarization terminal. To do. A DC voltage is applied between these two polarization terminals to polarize them.

After that, the conductive connection state is released. The substrate is a silicon single crystal substrate, and is surface-oxidized, and the transistor 2006 and other resistive elements 2007, 2008, 2011, and 2012 and wiring for making them into the circuit of FIG. 9 are internally formed. Has been done. The base portion, the emitter portion, and the ground portion of the transistor 2006 are electrically connected to the corresponding pad electrodes through the via holes provided in the surface oxide film. An insulating film is coated on the surfaces of the upper electrodes E and F to form the contact side with the object.

The operation of the above configuration will be described below. The high frequency pulse signal input to the terminal 2013 via the signal line 2 is transmitted to the capacitor 2004 and the S-mode piezoelectric vibrator 2003.
Coupling capacitor 200 divided by impedance ratio
The signal is input to the base of the transistor 2006 via 5.
This divided voltage signal has a larger value as the impedance of the piezoelectric vibrator increases. Therefore, when a high frequency pulse signal having a frequency corresponding to the anti-resonance frequency fa is input, the maximum voltage is exhibited, and when the load is applied, the anti-resonance resistance is gradually reduced and the divided voltage is gradually reduced.

On the other hand, since the anti-resonance frequency fa of the S-mode piezoelectric vibrator 2003 corresponds to the resonance frequency fr of the A-mode piezoelectric vibrator 2002, it exhibits the lowest impedance value Zr. Therefore, the combined resistance with the emitter resistance 2007 becomes the minimum, and the voltage amplification degree represented by the ratio of the load resistance 2008 and the combined resistance becomes the maximum. Further, when a load is applied, the resonance resistance Zr of the A-mode piezoelectric vibrator 2002 increases, so that the amplification degree decreases.

As described above, when a high-frequency pulse signal having the same frequency as the anti-resonance frequency fa of the S-mode piezoelectric vibrator 2003, that is, the resonance frequency fr of the A-mode piezoelectric vibrator 2002 is input, a DC pulse signal output to the terminal 2014. When the load is applied, the increase of the resonance resistance Zr of the A-mode piezoelectric vibrator 2002 and the decrease of the anti-resonance resistance Zr of the S-mode piezoelectric vibrator 2003 act synergistically to cause a large output change. You will get it.

With the structure of the tactile sensor circuit shown in FIGS. 9 and 10 as described above, a large sensitivity can be obtained, and a monolithic piezoelectric vibrator is used.
By embedding all the circuit elements other than the monolithic piezoelectric vibrator shown in FIG. 9 in a silicon substrate, it is possible to greatly reduce the size and to provide a sensor device that can be easily used in the fields of micro tactile sensing for medical use and the like. .

Incidentally, as shown in FIG. 11, even when only the S-mode piezoelectric vibrator 2003 is used, the anti-resonance frequency fa
And the anti-resonance resistance Zr can be obtained. According to the above-described structure of the piezoelectric vibrator, since the load receiving surface has no terminal structure, the load can be stably received with good reproducibility. Further, since the surface of the back surface for connecting the terminals is also in the same surface, it becomes easy to bond to the electrode pad arranged on the silicon substrate. When forming a film of the piezoelectric vibrator, the film is directly formed on the electrode pad arranged on the substrate in advance, and then,
No wiring is required just by forming the upper electrode, which leads to structural reliability improvement.

[In the above embodiment, a transistor is used as the amplifying element, but a FET is used instead of the transistor.
Alternatively, an operational amplifier may be used. When the FET is used, the circuit configuration is almost the same as the above embodiment,
When an operational amplifier is used, the circuit configuration is as shown in FIG.

Although the S-mode and A-mode oscillators are used as a pair, a combination of S-modes may be used as long as one anti-resonance frequency matches the other resonance frequency. In this case, the piezoelectric vibrator whose thickness changes midway is used.

Although the present invention has been described above based on the embodiments, the technical idea of the following constitution is derived from the present invention. (1). An input section for inputting an input signal having a different frequency according to the passage of time, an amplifying means for amplifying an input signal inputted from the input section, and an amplifying means provided for the amplifying means are provided for identifying the input signal. A resonance frequency of the piezoelectric vibrator based on an output of the amplifying means when the piezoelectric vibrator resonates, the input signal being input from the input unit. A sensor provided with signal processing means for separating and detecting a resonance resistance at the same time. (2). In configuration (1), the piezoelectric vibrator has first and second electrodes arranged in parallel on a first surface thereof, and first, second, and third electrodes arranged in parallel on a second surface thereof. A first piezoelectric vibrator for S-mode detection, which is composed of a first electrode provided on the first surface and a first electrode provided on the second surface, and Two different detection modes, that is, a second piezoelectric vibrator for A-mode detection, which includes a second electrode provided on the first surface and second and third electrodes provided on the second surface, are provided. A sensor, which is a monolithic piezoelectric vibrator in which a plurality of piezoelectric vibrators are formed on the same piezoelectric plate. (3). In the configuration (1), the amplification means is a transistor or a FET (field effect transistor),
The sensor, wherein the piezoelectric vibrator is connected in parallel to the emitter resistance of the transistor or the source resistance of the FET. (4). In the configuration (1), the amplification means is a transistor or a FET (field effect transistor),
The piezoelectric vibrator is the base or FE of this transistor.
A sensor characterized in that it is connected to the gate of T. (5). In the configuration (2), the amplifying means is a transistor or a FET (field effect transistor),
The first piezoelectric vibrator is connected in parallel to the emitter resistance of the transistor or the source resistance of the FET, and the second piezoelectric vibrator is connected to the base of the transistor or the gate of the FET. Sensor to do. (6). In the configuration (2), the amplifying means is an operational amplifier, the first piezoelectric vibrator is connected to a feedback portion of the operational amplifier, and the second piezoelectric vibrator is connected to a non-inverting input terminal of the operational amplifier. A sensor characterized by being present. (7). In a monolithic piezoelectric vibrator in which a plurality of piezoelectric vibrators are formed on the same piezoelectric plate, first and second electrodes are arranged in parallel on a first surface of the piezoelectric vibrator, and
First, second, and third electrodes are arranged in parallel on the second surface of the piezoelectric vibrator, and the first electrode provided on the first surface and the second electrode are provided on the second surface. The first electrode constitutes an S-mode piezoelectric vibrator, and the second electrode provided on the first surface and the second and third electrodes provided on the second surface. 1. A monolithic piezoelectric resonator characterized in that an A-mode piezoelectric resonator is constituted by. (8). In the configuration (7), the first and second electrodes on the first surface are electrodes not connected to terminals, and the first, second, and third electrodes on the second surface are terminal connection electrodes. The monolithic piezoelectric vibrator according to claim 5, wherein

The functions and effects of the above configurations (1) to (6) are as follows. (Operation) A change in impedance of the piezoelectric vibrator is separated into a change in resonance frequency and a change in resonance resistance and detected simultaneously. (Effect) It is possible to provide a sensor that can obtain the elastic characteristic and the viscous characteristic of a viscoelastic object that is a load from both the detected amounts of the change of the resonance frequency and the change of the resonance resistance.

The functions and effects of the above configurations (7) to (8) are as follows. (Function) First and second electrodes are arranged in parallel on the first surface of the piezoelectric vibrator, and first, second and third electrodes are arranged on the second surface of the piezoelectric vibrator. By arranging in parallel, the first electrode and the second electrode provided on the first surface are arranged.
S-mode piezoelectric vibrator including a first electrode provided on the surface of the second electrode, a second electrode provided on the first surface, and a second electrode provided on the second surface. A piezoelectric vibrator having two detection modes, which is an A-mode piezoelectric vibrator, is formed monolithically with the third electrode. (Effect) It is possible to provide a monolithic piezoelectric vibrator that is small and has improved measurement reliability. "

[0050]

According to the present invention, the resonance frequency and the resonance resistance of the piezoelectric vibrator can be separately obtained at the same time. In addition, a monolithic piezoelectric vibrator having a small size and improved measurement reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a tactile sensor circuit according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of a tactile sensor circuit.

FIG. 3 is a diagram showing a configuration of the FM modulator of FIG.

FIG. 4A is a diagram showing a high-frequency pulse signal waveform for a tactile sensor, and FIG. 4B is a diagram showing how the frequency of the high-frequency pulse signal in FIG. 4A changes with time.

FIG. 5 is a diagram showing a difference in impedance characteristic of the piezoelectric vibrator depending on presence / absence of a load.

FIG. 6 is a diagram showing a relationship between impedance characteristics of a piezoelectric vibrator and an output of a tactile sensor circuit.

FIG. 7 is a diagram showing a signal waveform of each part.

FIG. 8 is a diagram for explaining a second embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 10 is a cross-sectional view of a monolithic piezoelectric vibrator.

FIG. 11 is a diagram showing a modification of the third embodiment of the present invention.

FIG. 12 is a diagram showing a circuit configuration of an embodiment using an operational amplifier.

FIG. 13 is a diagram showing a configuration of a conventional sensor.

[Explanation of symbols]

88 ... Pressure electric vibrator, 89 ... Transistor, 90 ... Emitter resistance, 91 ... Collector resistance, 92, 93 ... DC bias resistance, 94 ... Power supply voltage supply terminal, 95 ... High frequency pulse signal input terminal, 96, 97 ... Capacitor, 98
... Output terminal.

Claims (2)

[Claims] 1. An input unit for inputting an input signal having a different frequency according to the passage of time, an amplifying unit for amplifying an input signal inputted from the input unit, and the amplifying unit. A piezoelectric vibrator that resonates with respect to a specific frequency of an input signal, and a resonance of the piezoelectric vibrator based on an output of the amplifying unit when the input signal is input from the input unit and the piezoelectric vibrator resonates. A signal processing unit that separates and simultaneously detects a frequency and a resonance resistance, and a sensor. 2. A monolithic piezoelectric vibrator in which a plurality of piezoelectric vibrators are formed on the same piezoelectric plate, wherein first and second electrodes are arranged in parallel on a first surface of the piezoelectric vibrator. First, second, and third electrodes are arranged in parallel on the second surface of the piezoelectric vibrator, and the first electrode provided on the first surface and the second electrode are provided on the second surface. An S-mode piezoelectric vibrator with the first electrode, and a second electrode provided on the first surface, and second and third electrodes provided on the second surface. 1. A monolithic piezoelectric resonator characterized in that an A-mode piezoelectric resonator is constituted by.