CN1141429A - Capacitive-component reducing circuit in electrostatic-type transducer means - Google Patents

Abstract

Driving voltage V is supplied to a piezo oscillator2 by means of an AC driving power source. A loop 8 is arranged at an electrode C of the piezo oscillator2; an electrostatic capacitor C<s> and an amplifier with a magnification coefficient of (N+1) are connected in series in the loop. When the capacitance of the electrostatic capacitor C<s> is arranged to be 1/N of the capacitance of the damping capacitor C<d >of the piezo oscillator2, the current i3 running through the damping capacitor C<d> will be substituted and shunted by the current i1 from the electrostatic capacitor C<s>, thus the damping capacitor C<d> does not consume driving current. Therefore, the small amount of the capacitance of the damping capacitor C<d> is determined by the capacitance of the electrostatic capacitor C<s> and the magnification coefficient of the amplifier and is irrelative to the frequency.

Description

Reduce the loop of capacitive component in the electrostatic sensor device

The present invention relates to the loop that reduces capacitive component of electrostatic sensor device, wherein the capacitive component of the damping capacitor of piezoelectric oscillator and electrostatic transducer is reduced or offsets, thereby can in such as the electrostatic sensor device of electrostatic transducer one class, realize effectively driving and super-sensitive vibration detection with piezoelectric oscillator, this electrostatic transducer utilize the distortion of piezoelectricity and have opposite each other, gapped therebetween electrode; The present invention simultaneously also further relates to the drive unit and the pick-up unit thereof of electrostatic sensor device.

The electrostatic sensor device is applied in the various technical fields.For example, electrostatic generator in the electrostatic sensor device can be used as the device that sends energy aspect electric in piezoelectric sender, the device of energy is dynamically sent in conduct in piezo-electric motor or piezoelectric actuator, the device of signal is mainly sent in conduct in piezolectric gyroscope, acceleration transducer, ultrasonic sensor, infrared ray sensor etc., as in the oscillation device of frequency source as the device that sends signal, in wave filter etc. as the device use of sending signal.Similarly, electrostatic transducer can be used for oscillation mode gyro, acceleration transducer, ultrasonic sensor, infrared ray sensor etc.

Figure 26 A to Figure 28 represents common example, and it is the piezoelectric oscillator as the electrostatic sensor device.Figure 26 A represents piezoelectric oscillator 1, and the equivalent circuit shown in Figure 26 B is illustrated near the piezoelectric oscillator 2 when tuning-points is to vibrate.

In these figure, the series resonance side of being made up of Rm, Cm and Lm 3 is represented the resonance of piezoelectric oscillator 2 of equal valuely.Cd in the parallel resonance side 4 represents the damping capacitor component of piezoelectric oscillator with series resonance side 3, and Figure 27 represents the admittance frequency characteristic of piezoelectric oscillator 2.In Figure 27, fa represents tuning-points (resonance frequency, series resonance point), and fb represents antiresonance point (anti-resonance frequency, parallel resonant point).

When piezoelectric oscillator was driven, the electric current that flows through damping capacitor Cd was a reactive current, and it provides energy can for the vibration of piezoelectric oscillator, therefore can increase the energy loss of device.Therefore, owing to electric current will be added on this damping capacitor Cd, so except making the real essential energy of piezoelectric oscillator vibration institute, drive power source also to damping capacitor Cd energize.

Figure 28 is an example in common loop, it when piezoelectric oscillator when tuning-points fa vibrates, offset the electric current that flows through damping capacitor Cd of equal valuely.

In this common example shown in Figure 28, have the coil 6 and pressure of inductance L d

Electrical oscillator 2 parallel connections.Here, the impedance Z m of series resonance side 3 represents with formula 1.

(formula 1) Zm=Rm+j (ω Lm+1/j ω Cm

AC power source 5 among Figure 28 is the power supply of constant voltage, if be added to piezoelectric vibration

Voltage on device 2 and the coil 6 represents with V, then flow to piezoelectric oscillator 2 and coil 6

Stream I represents with formula 2.

(formula 2) I=(1/Zm+j ω Cd+1/j ω Ld) V

＝{1/Zm＋j(ωCd-1/ωLd)}·V

By formula 2 as can be known, it is to satisfy the condition of formula 3 that electric current I becomes minimum condition, and electric current I can be represented with formula 4.

(formula 3) ω Cd=1/ ω Ld

(formula 4) I=(1/Zm) V

Like this, the coil with the inductance L d that represents with formula 5 is in parallel with piezoelectric oscillator, and its Chinese style 5 is launched to get for inductance L d by formula 3, the result, and the damping capacitor Cd of piezoelectric oscillator can be cancelled of equal valuely.

(formula 5) Ld=1/ ω ²Cd=1/ (2 π f) ²Cd

Offset the electric current that flows through damping capacitor Cd of equal valuely and the power source capacity of AC driving power source 5 can be reduced the amount that a quilt is offset like this.

For piezoelectric oscillator is driven under resonant condition, yet the driving frequency of AC driving power source must be near tuning-points fa or antiresonance point fb, in ceramic resonator of piezoelectric transition (PZT) (PZT) system etc., changes such as the elasticity factor of piezoelectric oscillator, and because the influence of the heat that the temperature variation of external environment and oscillator itself produce, the resonance frequency of ceramic resonator etc. can fluctuate.And, know that driving voltage also can make the resonance frequency fluctuation.Therefore, for often can be near tuning-points fa the drive pressure electrical oscillator, the essential resonance frequency that detects piezoelectric oscillator, and in desirable frequency range driving oscillator.So, can consider the drive unit of a tuning-points tracking mode, the frequency place of this device through being everlasting near resonance frequency is driven, and, in up-to-date piezo-electric motor etc., the sensor that detects the piezoelectric oscillator oscillatory regime is housed in this drive unit, and like this, the phase differential between the voltage of measuring according to drive current or driving voltage with by sensor can be followed the tracks of the fluctuation of piezoelectric oscillator tuning-points.

On the other hand, when piezoelectric oscillator is used as sensor in oscillation mode gyroscope etc., produce a problem, promptly because the influence of damping capacitor Cd effect, the detection voltage or the electric current that obtain from piezoelectric oscillator reduce, and can not detect the vibration of piezoelectric oscillator highly delicately.Because this problem, common actual practice is that inductance L d is in parallel with piezoelectric oscillator, offsetting or to reduce damping capacitor Cd of equal valuely, and so and improve its detection sensitivity, this situation to the drive pressure electrical oscillator is similar.

In addition, because the comparison bandwidth of wave filter is subjected to the restriction of the intrinsic electro-machanical coupling factor of piezoelectric oscillator, the comparison bandwidth for the extended filtering device is connected inductance L d with entry terminal.

Yet, as shown in Equation 5, offset the inductance L d and (driving frequency f) of damping capacitor Cd of equal valuely ²* (damping capacitor Cd) is inversely proportional to.Particularly, because square being inversely proportional to of Ld and driving frequency f, when because temperature change etc. when causing resonance frequency to change, under the situation of the difference increase of driving frequency and resonance frequency, the amount of offsetting damping capacitor Cd will sharply reduce of equal valuely.In addition, the size of general inductance L d wants big than All other routes element such as the size of resistance R and capacitor C, therefore is difficult to make the loop compact dimensions.In addition, in order to improve negative function of equal value, inductance must change and regulates according to piezoelectric oscillator.But, comparing with resistance R and electrostatic capacitance C, inductance is not suitable for changing operation.

Tuning-points tracking mode drive unit is partly by using sensor to realize that this sensor detects the oscillatory regime of piezoelectric oscillator in the mode similar to common piezo-electric motor.Yet, in other motors, there is not the sensor that can detect oscillatory regime best, therefore, be by detecting driving voltage, motor temperature waits and changes driving frequency, still, in this case, is difficult to follow the tracks of fully tuning-points.

In resembling the oscillation mode gyroscope, utilize under the situation of piezoelectric oscillator as sensor, the damping capacitor Cd that is used as the piezoelectric oscillator of testing goal can be reduced of equal valuely or eliminate by utilizing inductance L d.Yet because the function that reduces to act as frequency of equal value, it is very big that this effect size is influenced by driving frequency.In addition, such as already explained, general inductance is difficult to adjust, and the size of its electronic component is bigger than other electronic component dimensions.

When piezoelectric oscillator was used as wave filter, inductance L d was connected with the input-output terminal, to reach the bandwidth of broad.Yet, exist restrictive condition, promptly be difficult to make telefault to do to such an extent that size is less, and the effect of inductance is only just effective under a specific frequency.

As the electrostatic transducer of electrostatic sensor device, be same thing promptly with piezoelectric oscillator, it comprises the electrode that several are flat, these electrodes are opposite each other, and a narrow gap is arranged between them.When voltage is added on the gaps between electrodes, promptly carry out an operation, distance between electrodes is changed, on the contrary, when applying external force in a kind of mode that distance between electrodes is changed, then the voltage between the electrode changes.This loop that the driving of electrostatic transducer and the equivalence of operation detection add road and piezoelectric oscillator is the same.Therefore, also exist in electrostatic transducer and problem same in piezoelectric oscillator, promptly capacitive component consumes driving power, and in pick-up unit, capacitive component reduces the sensitivity that detects.

Consider above-mentioned shortcoming, therefore the objective of the invention is to provide a kind of loop of reducing capacitive component, this loop does not use inductance to reduce, and further offset the energy relevant with the capacitive component of electrostatic sensor device, purpose of the present invention also will provide a kind of and can drive the driving arrangement of electrostatic sensor device and a kind of pick-up unit that can detect the vibration of electrostatic sensor device highly delicately is provided in the mode of saving energy.

Another object of the present invention is that a kind of drive unit will be provided, and it can follow the tracks of resonance frequency frequently, and works as owing to temperature change, and driving voltage change etc. also can drive when causing the resonance frequency of electrostatic sensor device to fluctuate.

A further object of the invention is to build a self-vibration loop that comprises the electrostatic sensor device, makes to drive the electrostatic sensor device in resonance frequency or anti-resonance frequency place.

Be characterised in that according to minimizing capacitive component of the present invention loop there is an amplifier in this loop, it can be with the voltage amplification of electrostatic sensor device one side, and this loop also has a passage that the described side of the amplification output terminal of this amplifier and electrostatic sensor device is coupled together by electrostatic capacitance, like this, the capacitive component of electrostatic sensor device can reduce to minimum.

The electrostatic sensor device for example can be represented with piezoelectric oscillator, and this oscillator is electrostrictive transducer or electrostatic transducer, and wherein flat electrode is opposite each other, and a little gap etc. is arranged between them.Under the piezoelectric oscillator situation, capacitive component is a damping capacitor, and under the electrostatic transducer situation, capacitive component is the capacitive component between electrode opposite each other.

In above situation, if when electrostatic capacitance is approximately the 1/N of capacitive component of electrostatic sensor device, then preferably make the enlargement factor of amplifier be approximately the electrostatic sensor device capacitive component (N+1) doubly.

In this case, if represent with V at the voltage of electrostatic sensor device one side, then at the voltage of amplifier outlet terminal, the voltage that promptly is added on electrostatic sensor device and the mutual electrostatic capacitance of connecting is V (N+1).

If the electrostatic sensor device is a piezoelectric oscillator, then electrostatic capacitance can be made with the same material that constitutes this piezoelectric oscillator.

According to the present invention, a kind of drive unit is provided, it comprises: driving power is supplied to the passage of electrostatic sensor device and reduces the capacitive component loop by it, wherein reduces amplifier in the capacitive component loop and is positioned at by described passage and is supplied to the position that the driving power of electrostatic sensor device is exaggerated.

In a loop configuration example of this situation, as shown in Figure 1, built a loop, in this loop, driving power at first is supplied to the C end of electrostatic sensor device, then, passage is held from described C, gets back to described C end through amplifier 7 and electrostatic capacitance Cs.Perhaps, as shown in figure 21, the passage that driving power is supplied to electrostatic sensor device C ' end is connected and configuration in parallel with the passage that electrostatic capacitance Cs arrives described C ' end by amplifier 7 with driving power.The loop of Fig. 1 is the same with loop shown in Figure 21 in essence.Yet, if the loop makes as shown in Figure 1, uprise when frequency of utilization, and the amplification coefficient of amplifier 7 may produce vibration when also uprising.Like this, preferably as shown in figure 22, when driving power is supplied to the passage of electrostatic sensor device when in parallel with the passage with amplifier and electrostatic capacitance by it, then between driving power supply side and electrostatic sensor device, in being supplied to the described passage of electrostatic sensor device, driving power is provided with voltage retaining device.

In addition, also be equipped with: current phase pick-up unit, phase comparator, wave filter and voltage-controlled oscillator; The current phase pick-up unit is used to detect the current phase that flows through the electrostatic sensor device, phase comparator is used for comparison by detected current phase of described current phase pick-up unit and the voltage-phase that is supplied to the driving power of electrostatic sensor device, wave filter filters the high fdrequency component of described phase comparator, voltage-controlled oscillator is controlled oscillation frequency changeably according to the resulting output voltage in described filter filtering operation back, like this, can supply with driving power according to the oscillation frequency of described voltage-controlled oscillator, and the electrostatic sensor device can be driven under resonance frequency.

In these cases, when the electrostatic sensor device is piezoelectric oscillator, the oscillation frequency of described voltage-controlled oscillator is variable control in such a way, and promptly the phase differential that is relatively drawn between current phase and voltage-phase by described phase comparator is zero.

Secondly, pick-up unit according to the present invention is characterised in that, can obtain electric output from the electrostatic sensor device that is forced its vibration by external force, and be furnished with the loop that reduces capacitive component in pick-up unit.

In addition, drive unit according to the present invention has frequency selection loop and amplifier; This frequency selects the loop to comprise capacitive component and resistive component in the electrostatic sensor device, and in amplifier, this frequency selects the loop to be located in the positive feedback loop, and this drive unit is characterised in that, carries out self-vibration under the frequency of being selected the loop decision by described frequency.

In these cases, described frequency selects the loop by first resistance of connecting in the positive feedback loop of described amplifier and first capacitor and in parallel, and second resistance and second capacitor that are connected the irreversible input side of described amplifier are formed, this frequency selects the loop to constitute like this, promptly or be first resistance and first capacitor, or the capacitive component and the resistive component of second resistance and second capacitor and electrostatic sensor device adapt.

Particularly, as shown in Figure 9, structure can be such, promptly first electric capacity and first resistor are connected in the positive feedback loop of amplifier, piezoelectric oscillator or be connected with the irreversible input side of amplifier such as the electrostatic sensor device of electrostatic transducer one class, self-vibration is being produced by described first capacitor and first resistance and near become the electrostatic sensor device of driving condition tuning-points the frequency place that capacitive component and resistive component determined.Perhaps, as shown in figure 11, structure can be such, be that the electrostatic sensor device is connected with the positive feedback loop of amplifier, second electric capacity that is connected in parallel to each other is connected with the irreversible input side of amplifier with second resistance, and self-vibration produces at the frequency place that is determined by near the capacitive component of the electrostatic sensor device that becomes driving condition antiresonance point and resistive component and second capacitor and second resistance.

In addition, preferably structure is such, promptly capacitive component and resistive component as Fig. 9 and C ' among Figure 11 be connected with the electrostatic sensor device like that shown in the R '.

In addition, in these cases, be preferably in the negative feedback loop of amplifier an amplitude stability loop that comprises the resistance that can determine the amplifier amplification coefficient is set.

Reducing in the capacitive component loop according to of the present invention, be supplied to such as the voltage of electrostatic sensor device one side of piezoelectric oscillator one class or the voltage that produces in described side and amplify, the voltage of this amplification is added on the electrostatic capacitance of connecting with the electrostatic sensor device again by amplifier.Therefore, the capacitive component of electrostatic sensor device has been offset in the existence of flowing through the electrostatic capacitance electric current, the damping capacitor of piezoelectric oscillator for example, and the result makes the work of electrostatic sensor device capacitive component reduce to minimum.

In these cases, set when the enlargement factor of amplifier and to be approximately (N+1), and electrostatic capacitance is approximately the 1/N of the capacitive component of electrostatic sensor device, that is the voltage that ought be added on electrostatic sensor device and the electrostatic capacitance is set at V (N+1), and be supplied to the voltage of electrostatic sensor device one side or when the voltage that described side produces was defined as V, the capacitive component of electrostatic sensor device almost can be cancelled fully.If even electrostatic capacitance can not with the strict coupling of this value, the effect of this minimizing capacitive component also can reach.

When the electrostatic sensor device was piezoelectric oscillator, electrostatic capacitance can be with making with the material identical materials of piezoelectric oscillator.In this case, piezoelectric oscillator and electrostatic capacitance are to be under the situation of equal value for the environmental baseline such as temperature one class, and therefore, capacitive component can further reduce effectively.

In drive unit according to the present invention, be added with driving power in a side (one of electrode) such as the electrostatic sensor device of piezoelectric oscillator one class.Driving power is exaggerated device through different passages and amplifies, and the voltage of this amplification is added on the electrostatic capacitance that is connected described side from supplying with the place of described driving power.Utilize this to reduce the capacitive component loop, can make the capacitive component of electrostatic sensor device reduce to minimum or be cancelled, like this, capacitive component is consumed power not.Therefore can reach the driving operation of saving energy.

In addition, when the setting that is connected in parallel to each other of the passage that driving power is supplied to the electrostatic sensor device and the passage that comprises amplifier and electrostatic capacitance, and when being placed between driving power supply side and the electrostatic sensor device, in the described passage that driving power is supplied to the electrostatic sensor device, be provided with such as the voltage retaining device of voltage-tracing device one class and can realize stable driving operation, can not produce vibration.

If the frequency of driving power is so variable chemical control system, promptly be supplied to the bit comparison mutually of phase place and the electric current that flows into the electrostatic sensor device of the driving voltage of electrostatic sensor device, the phase differential of voltage and current is zero, for example under the situation of piezoelectric oscillator, then the electrostatic sensor device can be driven through be everlasting resonance frequency or anti-resonance frequency place.Even when the resonance frequency of electrostatic sensor device or anti-resonance frequency fluctuation, driving power is often followed the tracks of the fluctuation of this frequency therefore.

In addition, in the drive unit of electrostatic sensor device according to the present invention, be provided with amplifier (operational amplifier), and in the positive feedback loop (positive feedback passage) of described amplifier, be provided with frequency and select the loop, simultaneously described frequency selects the loop to comprise the capacitive component and the resistive component of electrostatic sensor device, more particularly, comprise the capacitive component and the resistive component that are in the electrostatic sensor device under resonance (series resonance) or antiresonance (parallel resonance) state, like this, self-vibration can be carried out near the tuning-points of electrostatic sensor device or antiresonance point.

This drive unit has used Wei En (Wien) bridge oscillator circuit theory.Frequency in this oscillator loop is selected the loop, for example can be by being one another in series, be included in first capacitor and first resistance in the positive feedback loop of amplifier and be connected in parallel to each other, second capacitor and second resistance that are connected the irreversible input side of amplifier constitute.Here, can also build a self-vibration loop, its frequency of operation is by the decision like this of the capacitive component of electrostatic sensor device and resistive component, promptly or be first capacitor and first resistance, or near the electrostatic sensor device that tuning-points or antiresonance point, driven of second capacitor and second resistance replace.

In addition, select in the loop in said frequencies, first and second capacitors play Hi-pass filter and low-pass filter effect respectively, so that construct a bandpass filter between the input and output of amplifier, the natural frequency of vibration can determine like this.Here, may produce a situation, promptly between such as the resonance frequency of the electrostatic sensor device of piezoelectric oscillator one class or anti-resonance frequency, have difference, and the natural frequency of vibration be selected the loop decision by described frequency.Like this, as Fig. 9 or shown in Figure 11, additional capacitor C ' and additional resistance R ' and electrostatic sensor device are in parallel or connect, and this additional capacitor and additional resistance play the effect of the cutoff frequency of adjusting described low-pass filter and Hi-pass filter, as a result, the self-vibration operation can be carried out at the resonance frequency or the anti-resonance frequency place of electrostatic sensor device.

In addition, the resistance that the decision amplification coefficient is set in the negative feedback loop of amplifier can be stablized the amplitude of self-vibration.

Fig. 1 is the equivalent circuit figure of the drive unit of expression piezoelectric oscillator according to an embodiment of the invention.

Fig. 2 is the loop diagram of an equivalence, the state that its expression and the damping capacitor component of piezoelectric oscillator shown in Figure 1 are offset of equal valuely.

Fig. 3 A and Fig. 3 B are the figure of the frequency characteristic of the current gain of expression piezoelectric oscillator shown in Figure 1 and phase place.

Fig. 4 is the equivalent circuit figure that is used for the common piezoelectric oscillator drive unit of experiment purpose.

Fig. 5 is the figure of the experimental result of the common piezoelectric oscillator drive unit of expression

Fig. 6 is the equivalent circuit figure according to piezoelectric oscillator drive unit of the present invention that is used for experiment purpose.

Fig. 7 is the figure of expression according to the experimental result of piezoelectric oscillator drive unit of the present invention.

Fig. 8 is used to the side view of the piezoelectric oscillator structure of testing in the present invention for expression.

Fig. 9 is the equivalent circuit figure of the drive unit from vibration shape piezoelectric oscillator according to an embodiment of the invention.

Figure 10 A and Figure 10 B are near the equivalent circuit figure of the piezoelectric oscillator shown in Figure 9 tuning-points.

Figure 11 is the equivalent circuit figure of self-excited oscillating type piezoelectric oscillator drive unit according to another embodiment of the present invention.

Figure 12 A and Figure 12 B are near the equivalent circuit figure of the piezoelectric oscillator shown in Figure 11 antiresonance point.

Figure 13 is the equivalent circuit figure of the drive unit of resonant tracking piezoelectric oscillator according to an embodiment of the invention.

Figure 14 A and Figure 14 B are the gain of expression piezoelectric oscillator supplying electric current shown in Figure 13 and the figure of phase propetry thereof.

Figure 15 is the equivalent circuit figure of piezoelectric oscillator pick-up unit according to an embodiment of the invention.

Figure 16 is a loop diagram of equal value, the state that the damping capacitor component of the piezoelectric oscillator that its expression is shown in Figure 15 is offset of equal valuely.

Figure 17 is the wiring diagram of equal value that is used for the common piezoelectric oscillator pick-up unit of experiment purpose.

Figure 18 is the figure of the experimental result of the common piezoelectric oscillator pick-up unit of expression

Figure 19 is the equivalent circuit figure according to the pick-up unit of piezoelectric oscillator of the present invention, as to be used for experiment purpose.

Figure 20 is the figure of expression according to the experimental result of piezoelectric oscillator pick-up unit of the present invention.

Figure 21 is the equivalent circuit figure of expression according to the piezoelectric oscillator drive unit of another structural drawing of the present invention.

Figure 22 carries out the equivalent circuit figure of improved better example to piezoelectric oscillator drive unit shown in Figure 21 for expression.

Figure 23 is a loop diagram of equal value, and it has represented an example, and structure applications wherein shown in Figure 22 is in resonant tracking drive unit shown in Figure 13.

Figure 24 A and Figure 24 B are respectively the drive unit of electrostatic transducer and the structural drawing of its equivalent circuit figure.

Figure 25 A and Figure 25 B are respectively the pick-up unit of use electrostatic transducer and the structural drawing of its equivalent circuit figure.

Figure 26 A and Figure 26 B are respectively at the piezoelectric oscillator of tuning-points and the loop diagram of equivalent circuit thereof.

Figure 27 is the figure of the frequency characteristic of expression piezoelectric oscillator admittance.

Figure 28 is the loop diagram that common piezoelectric oscillator drives the loop, and wherein the damping capacitor component of piezoelectric oscillator has been offset of equal valuely.

Piezoelectric oscillator or flat electrodes electrostatic transducer opposite each other can be used as the example of electrostatic sensor device.In the following embodiments, will begin to utilize piezoelectric oscillator as an example the electrostatic sensor device to be described.

Fig. 1 is the equivalent circuit figure of the drive unit of expression piezoelectric oscillator according to an embodiment of the invention.

Referring to Fig. 1, an electrode of piezoelectric oscillator 2 (in equivalent circuit figure, being expressed as near the state that vibrates the tuning-points that is in) ground connection, and another electrode (being in a side in the present invention) is connected with AC driving power source 5.Amplifier 7 is connected with another electrode, in amplifier 7, is added to the voltage on this electrode, promptly the driving power voltage of supplying with by AC driving power source 5 be amplified to gain (N+1) doubly.At the amplification output terminal of this amplifier 7, the capacitor that electrostatic capacitance is Cs of connecting, this electrostatic capacitance Cs connects with piezoelectric oscillator 2 at another electrode place, and comprises that the loop 8 (reducing the capacitive component loop) of this amplifier and Cs is connected the C point.The capacitance of electrostatic capacitance Cs is approximately the 1/N of the damping capacitor Cd of piezoelectric oscillator 2.This loop 8 is exactly according to capacitive component (damping capacitor) loop that reduces of the present invention.

In Fig. 1, represent with i by the supplying electric current that AC driving power source 5 is supplied with, the electric current that flows through electrostatic capacitance Cs is represented with i1, the impedance of the series resonance side 3 of piezoelectric oscillator 2 is represented with Zm, and the electric current that flows through it is represented with i2, the electric current that flows through damping capacitor Cd represents with i3, and the electric current that flows through amplifier 7 is represented with i4.

Owing to be added in the C point from the driving voltage V of AC driving power source 5, because the effect of amplifier 7, the current potential that D is ordered will be (N+1) V.Like this, the voltage that equals NV is added in (D-C) between a D and the C.Because the impedance at D-C place is 1/ (j ω Cs), so i1 can represent that wherein ω is an angular frequency with formula 6.

(formula 6) i1=j ω CsNV

Similarly, i2 and i3 can represent with formula 7 and formula 8 respectively.

(formula 7) i2=V/Zm

(formula 8) i3=j ω CdV

Because i4 is very little electric current, if when not considering i4, then i can represent with formula 9.

(formula 9) i=i2+i3-i1

Formula 6,7 and 8 substitution formulas 9 can be got formula 10.

(formula 10) i=V/Zm+j ω (Cd-NCs) V

Here, if formula 11 establishments,

(formula 11) Cs=Cd/N

Then i will equal the right-hand vector of formula 7, and i equals i2, promptly only the supplying electric current of supplying with from AC driving power source 5 will be thought of as the amount of the impedance Z m that flows into series resonance side 3, and not have current supply to damping capacitor Cd, and this electric capacity just can not work to vibration.

Because the damping capacitor Cd component of piezoelectric oscillator is offset of equal valuely, therefore, will be the loop of only being formed by series resonance side 3 shown in Figure 2 corresponding to the equivalent circuit of this state of piezoelectric oscillator.The gain characteristic of the supplying electric current i that is supplied with by AC driving power source 5 represents that with formula 12 tuning-points fa represents that with formula 13 phase propetry is represented with formula 14.Fig. 3 A represents the frequency characteristic of the gain of supplying electric current i, and Fig. 3 B represents the frequency characteristic of the phase place of supplying electric current i.

(formula 12) i=V/Zm=V/{Rm+j (ω Lm-1/ ω Cm) } $=V\&CenterDot;{\mathrm{\&epsiv;}}^{\mathrm{j\&theta;}}/\left[\sqrt{\{{\mathrm{<figure-callout\; id="2"\; label="Rm"\; filenames="A9610040200411.png"\; state="\{\{state\}\}">Rm</figure-callout>}}^2+{(\mathrm{\&omega;Lm}-1/\mathrm{\&omega;Cm})}^2\}}\right]$

(formula 13) $\mathrm{fa}=1/\left\{2\mathrm{\&pi;}\sqrt{(\mathrm{Lm}\&CenterDot;\mathrm{Cm})}\right\}$

(formula 14) θ=-tan ^-1{ (ω Lm-1/ ω Cm)/Rm}

Flowing through the condition that the electric current of damping capacitor Cd is cancelled is to satisfy formula 11, and promptly electrostatic capacitance Cs is the 1/N of damping capacitor Cd.This condition is provided by the function of the gain N of electrostatic capacitance Cs and amplifier 7, does not comprise the function of drive frequency of AC driving power source 5.Therefore, frequency dependence is not included in the condition of offsetting damping capacitor Cd.Because in the process of offsetting damping capacitor Cd, it is more much easier than adjusting inductance L to adjust electrostatic capacitance Cs, even therefore utilize the variable electrostatic capacitance of varactor or vernier capacitor formula also can be very compact.In addition, if gain N is regulated by variable resistor, and electrostatic capacitance Cs fixes, and also can obtain similar superior effect, can do compactlyer like this.Certainly, can reach superior effect, even the condition set of the gain of the electrostatic capacitance Cs that will realize and amplifier 7 and formula 11 is not to mate finely like this, the influence of damping capacitor Cd also can reduce.

The electronic component of actual realization electrostatic capacitance Cs can be made with the same material of making piezoelectric oscillator 2.The part material that constitutes piezoelectric oscillator can not be that polarization is handled, and this part can be used as electrostatic capacitance Cs.Like this, the part of same material is that polarization is handled, so that make piezoelectric oscillator, and another part is not the polarization processing, so that make electrostatic capacitance Cs, so no longer needs to possess especially an element as electrostatic capacitance Cs.Therefore, not only reached cost efficiency, and can reduce many essential parts, device size can be done compactlyer like this.Amplifier 7 is for amplifying the device of voltage, and amplifier 7 can be by transistor, operational amplifier, formations such as transformer.

Fig. 5 and Fig. 7 represent the experimental result of common loop and one embodiment of the invention respectively.

Fig. 8 represents to test the component parts 10 of used piezoelectric oscillator.Referring to Fig. 8, electrode 13, piezoelectric 12 and drive electrode 11 are placed on the side surface of glass substrate 14, and electrode 15, piezoelectric 16 and detecting electrode 17 are placed on the opposite side surface of glass substrate 14 similarly.Piezoelectric 12 and 16 non-conductive polarised direction are represented with arrow shown in Figure 8.

Fig. 5 represents to utilize the experimental result in common loop, does not realize in this common loop according to loop 8 of the present invention (reducing the capacitive component loop).Fig. 4 is the experimental loop in the common loop of use, and Fig. 5 represents the output with ammeter shown in Figure 49 detections.Referring to Fig. 4, an electrode grounding of piezoelectric oscillator 2, and another electrode is connected with AC driving power source 5, ammeter 9 connects and is placed between piezoelectric oscillator 2 and the AC driving power source 5.Used piezoelectric oscillator 2 is a component parts 10 shown in Figure 8 in the experiment, and the drive electrode 11 of component parts 10 is connected with the terminal A of experimental loop shown in Figure 4, and the electrode 13 of component parts 10 is connected with the terminal B of experimental loop shown in Figure 4.

Fig. 5 represents a figure, and its axis of abscissa is represented the frequency of the driving power supplied with by AC driving power source 5, and Y axis Y represents the gain (dB) of the supplying electric current i that supplied with by the AC driving power source, also represents the phase theta (degree) of supplying electric current i.Output X represents gain characteristic, and the maximal value of gain appears at tuning-points fa, and the minimum value of gain appears at antiresonance point fb.Output Y represents phase propetry, and except near tuning-points fa and antiresonance point fb, under the influence of damping capacitor Cd, the phase place of supplying electric current i is all spent than driving voltage leading 90 on each frequency.

Fig. 7 represents the experimental result of utilizing one to realize according to the loop of loop 8 of the present invention (reducing the capacitive component loop).Fig. 6 represents experimental loop, and Fig. 7 represents the output by ammeter detection shown in Figure 6.Referring to Fig. 6, an electrode grounding of piezoelectric oscillator 2, and another electrode of piezoelectric oscillator 2 is connected with AC driving power source 5, makes driving power supply with piezoelectric oscillator 2 by terminal A.As reducing in the loop 8 in capacitive component loop, the voltage on the terminal A is exaggerated device 7 and amplifies a N+1 coefficient in the feed path of driving power.Electrostatic capacitance Cs connects with the amplification output terminal of amplifier 7, and is connected with terminal A.The approximate 1/N that is set at damping capacitor Cd of electrostatic capacitance Cs.

Ammeter 9 connects and is placed between piezoelectric oscillator 2 and the AC driving power source 5.For the piezoelectric oscillator that in experiment, uses, used component parts 10, and the drive electrode 11 of component parts 10 is connected with the terminal A of experimental loop, and the electricity level 13 of component parts 10 is connected with the terminal B of experimental loop.By amplifier 7, negative feedback loop piece 19 constitutes with the positive feedback loop piece 18 that comprises electrostatic capacitance Cs according to device embodiment illustrated in fig. 6; Amplifier 7 is an operational amplifier, and negative feedback loop piece 19 comprises resistance R 3 and R4, in order to the gain of setting voltage amplification.Each parameter suc as formula 15 and formula 16 shown in set like that.

(formula 15) N+1=1+ (R3/R4)

(formula 16) Cs=Cd/N

Fig. 7 represents a figure, and its axis of abscissa is represented frequency, and its Y axis Y is represented the gain (dB) by the supplying electric current i of AC driving power source supply, also represents the phase theta (degree) of supplying electric current i.Output X represents gain characteristic.Damping capacitor Cd is offset of equal valuely, and gain reaches maximal value at tuning-points fa place.Output Y represents phase propetry.Referring to Fig. 7, as can be seen, at tuning-points fa place, with respect to the driving voltage phase place, phase place is almost nil, and from this frontier point, leading about 90 degree of current phase, about 90 degree of phase lag then.

The output characteristics of comparison diagram 5 and Fig. 7 can be sure of, can offset the component of damping capacitor Cd by adding loop shown in Figure 68 (reducing the capacitive component loop) of equal valuely, and can reducing one, driving power applies watt level that damping capacitor Cd is consumed by AC driving power source 5.

Fig. 9 and Figure 11 represent the drive unit of piezoelectric oscillator, and this piezoelectric oscillator is the self-vibration loop 20 according to the embodiment of the invention.

Form by amplifier 27, the negative feedback loop piece 23 that is connected with amplifier and positive feedback loop piece 22 according to device embodiment illustrated in fig. 9; Amplifier 27 is an operational amplifier, and negative feedback loop piece 23 comprises resistance R 3 and R4, is used for the gain that setting voltage amplifies, and positive feedback loop piece 22 is connected with piece 23 by amplifier 27, and it comprises electrostatic capacitance Cs, resistance R 1 and piezoelectric oscillator 1.

Still referring to Fig. 9, positive feedback loop piece 22 is selected the loop for frequency, wherein electrostatic capacitance Cs connects with resistance R 1, and the circuit of this series connection is connected in the positive feedback passage 22a of amplifier 27 (positive feedback loop), promptly is connected in the passage that outgoing side and irreversible input side with amplifier 27 couple together.An input that electrode is the irreversible input side of amplifier 27 of piezoelectric oscillator 1, and another electrode grounding of piezoelectric oscillator 1.Negative feedback loop piece 23 is the amplitude stability loop, the gain that its setting voltage amplifies, wherein be provided with the negative feedback channel 23a (negative feedback loop) that is connected with the reversible side entry terminal of amplifier 27 by resistance R 3, resistance R 4 connects and is placed between the irreversible input side and ground of amplifier 27 simultaneously.

Figure 10 A is near the equivalent circuit that piezoelectric oscillator obtains when being driven tuning-points fa, and at tuning-points fa, Lm and Cm are series resonances, and are equivalent to the state shown in Figure 10 B.For the equivalent circuit shown in Figure 10 B, tuning-points fa can be obtained by formula 17.

(formula 17) $\mathrm{fa}=1/2\mathrm{\&pi;}\sqrt{(\mathrm{Lm}\&CenterDot;\mathrm{Cm})}$

Simultaneously, (suppose that the loop does not have additional resistance R ' and additional capacitor C ') in loop shown in Figure 9, piezoelectric oscillator 1 is replaced by the series resonance equivalent circuit, like this, comes the loop is analyzed.The result who analyzes will be illustrated below.

If the voltage on the irreversible entry terminal of amplifier 27 is represented with ei, the voltage ei ' expression of reversible entry terminal, output voltage is represented with eo, then sets up as follows by the relation of formula 18 and formula 19 expressions.

(formula 18) ei=eo/{ (1+R1/Rm+Cd/Cs)+

j(ωCdR1－1/ωCsRm)}

(formula 19) ei '={ R4/ (R3+R4) } eo

If the enlargement factor of amplifier 27 (operational amplifier) is enough big, then the relation of formula 20 is set up.Then, with formula 18 and formula 19 substitution formulas 20, can obtain formula 21.

(formula 20) ei=ei '

(formula 21) R4/ (R3+R4)=1/{ (1+R1/Rm+Cd/Cs)+

j(ωCdR1－1/ωCsRm)}

By formula 21 as can be known, the oscillating condition in the driving loop 20 of piezoelectric oscillator 1 is such, and promptly amplitude condition is by formula 22 expressions, and frequency condition is by formula 23 expressions.

(formula 22) (R3+R4)/R4=1+R1/Rm+Cd/Cs

(formula 23) ω CdR1=1/ ω CsRm

Here, satisfy each parameter of above-mentioned amplitude condition and frequency condition, as R1, R3, R4 and Cs can select like this, even loop 20 becomes the self-vibration loop in piezoelectric oscillator tuning-points fa vibration.

In other words, this self-vibration loop is the loop of utilization Wei grace (Wien) bridge oscillator circuit theory.In Wei grace bridge oscillator loop, positive feedback is added on the amplifier (operational amplifier) 27, vibrate to produce, and this natural frequency of vibration is to be determined by the positive feedback loop piece 22 of selecting the loop as frequency.In positive feedback loop piece 22 (frequency selection loop), the first capacitor C s and first resistance R 1 are connected in positive feedback loop, and the Cd of the piezoelectric oscillator 1 of equivalent circuit shown in Figure 10 B and Rm are used separately as second electric capacity and second resistance.Second electric capacity and second resistance are parallel with one another, and are connected with the irreversible input side of amplifier 27.Select in the loop in frequency, the first capacitor C s (electrostatic capacitance) plays the Hi-pass filter effect, and second electric capacity (damping capacitor) Cd plays the low-pass filter effect.The bandpass filter decision that the natural frequency of vibration is made up of Hi-pass filter in the positive feedback passage of amplifier 27 and low-pass filter.

Negative feedback loop piece 23 works to stablize the self-vibration amplitude loop in such a way, and promptly it can get the voltage amplification gain setting of amplifier 27 enough high.

Here, the resonance frequency of piezoelectric oscillator 1 is by formula 17 decision, promptly during movement by the inductive component Lm and the capacitive component Cm decision of piezoelectric oscillator 1.This situation may occur, promptly this resonance frequency can not often be mated with selected the natural frequency of vibration of loop decision by frequency.

In this case, preferably each capacitance and resistance value are according to having additional capacitor C ' and additional resistance R ' to regulate with piezoelectric oscillator 1 this mode in parallel or selecting, as shown in Figure 9.In this case, the work of additional capacitor C ' can be adjusted the cutoff frequency of low-pass filter, and the work of additional resistance R ' can be adjusted the cutoff frequency of Hi-pass filter.As a result, can proofread and correct, make the resonance frequency coupling of the natural frequency of vibration in self-vibration loop 20 and piezoelectric oscillator 1 or approximate.Therefore, preferably additional capacitor C ' and additional resistance R ' are made of free variable elements, and/or electrostatic capacitance Cs and resistance R 1 are made of free variable element.

Secondly, in the embodiment shown in fig. 11, amplifier 37 is an operational amplifier, and what be connected with operational amplifier has negative feedback loop piece 33 and a positive feedback loop piece 32; Negative feedback loop piece 33 comprises resistance R 3 and R4, the gain of amplifying in order to setting voltage, and positive feedback loop piece 32 is made of electrostatic capacitance Cs and resistance R 2 and piezoelectric oscillator 1.Positive feedback loop piece 32 is selected the loop for frequency, has wherein built positive feedback passage (positive feedback loop) 32a that comprises piezoelectric oscillator, has promptly built a passage that the outgoing side and the irreversible input side of amplifier 37 are coupled together; Piezoelectric oscillator 1 is connected in this passage.Electrostatic capacitance Cs and resistance R 2 are parallel with one another, and are connected with ground with the irreversible input side of amplifier 37.Be provided with negative feedback loop piece 33, so that, also construct a negative feedback channel 33a who is connected with the reversible entry terminal of amplifier 37 by resistance R 3 simultaneously by voltage amplification gain setting to enough high levels are come stabilized amplitude.Resistance R 4 connects and is placed between the reversible input side and ground of amplifier 37.

Figure 12 A is near the equivalent circuit that piezoelectric oscillator 1 obtains when being driven antiresonance point fb.At antiresonance point fb place, Lm ' and Cm ' are parallel resonance, and with the state equivalent shown in Figure 12 B.The antiresonance point fb of the equivalent circuit shown in Figure 12 B can be drawn by formula 24.

(formula 24) $\mathrm{fb}=1/2\mathrm{\&pi;}\sqrt{(\mathrm{Lm}\text{'}\&CenterDot;\mathrm{Cm}\text{'})}$

Simultaneously, (suppose that the loop does not have additional capacitor C ' and additional resistance R ') in loop shown in Figure 11, piezoelectric oscillator 1 is replaced by the parallel resonance equivalent circuit, and this loop is analyzed.The result who analyzes will be described below.

If the voltage on amplifier 37 irreversible entry terminals is represented with ei, the voltage ei ' expression of irreversible terminal, output voltage represents that with eo then the relation by formula 25 and formula 26 expressions is as follows.

(formula 25)

ei＝eo/{(1＋Rm’/R2＋Cs/Cd’)＋j(ωCsRm’－1/ωCd’R2)}

(formula 26) ei '={ R4/ (R3+R4) } eo

If the enlargement factor of amplifier 37 (operational amplifier) is enough big, then the relation of formula 27 is set up.Then, formula 25 and formula 26 substitution formulas 27 can be got formula 28

(formula 27) ei=ei '

(formula 28) R4/ (R3+R4)=1/{ (1+Rm '/R2+Cs/Cd ')+j (ω CsRm '-1/ ω Cd ' R2) }

By formula 28 as can be known, the oscillating condition that comprises the self-vibration loop 30 of piezoelectric oscillator 1 is that amplitude condition is represented with formula 29, and frequency condition is represented with formula 30.

(formula 29) (R3+R4)/R4=1+Rm '/R2+Cs/Cd '

(formula 30) ω CsRm '=1/ ω Cd ' R2

Here, satisfy each parameter of amplitude condition and frequency condition, as R2, R3, R4 and Cs select like this, even this loop becomes the self-vibration loop in the vibration of piezoelectric oscillator antiresonance point fb place.

The principle in self-vibration loop shown in Figure 11 can be used Wei grace (Wien) bridge oscillator loop circuit representation, and it is identical with principle shown in Figure 9.When in Figure 11, the equivalent circuit shown in piezoelectric oscillator 1 usefulness Figure 12 B replaces, and first electric capacity and first resistance are respectively Cd ' and Rm ', and second electric capacity and second resistance are respectively Cs and R2.In that loop, near the damping capacitor Cd ' of the piezoelectric oscillator 1 of working antiresonance point plays Hi-pass filter, and electrostatic capacitance Cs plays the low-pass filter effect.

Here, the anti-resonance frequency of piezoelectric oscillator is by formula 24 decisions.Then, a kind of situation may appear, wherein this anti-resonance frequency can not be often and the natural frequency of vibration in self-vibration loop 30 be complementary.In this case, preferably additional capacitor C ' is connected with piezoelectric oscillator 1 with additional resistance R ', as shown in figure 11.In this case, the effect of additional capacitor C ' is the frequency of passing through of proofreading and correct Hi-pass filter, and the effect of additional resistance R ' is the frequency of passing through of proofreading and correct low-pass filter.Like this, the natural frequency of vibration in self-vibration loop 30 can be mated with the anti-resonance frequency of piezoelectric oscillator 1 or be approximate.In this embodiment, preferably additional capacitor C ' and additional resistance R ' and/or electrostatic capacitance Cs and resistance R 2 also are made up of free variable elements.

Should be appreciated that in Figure 11, additional capacitor C ' and additional resistance R ' can be in parallel with piezoelectric oscillator 1, and in Fig. 9, additional capacitor C ' and additional resistance R ' can connect with piezoelectric oscillator 1.In addition, such structure can also be arranged, among additional capacitor C ' or the additional resistance R ' any one promptly is set in Fig. 9 and Figure 11.In other words, in the operation near the natural frequency of vibration, any one is effective in adjustment Hi-pass filter or the low-pass filter in resonance frequency that makes piezoelectric oscillator or anti-resonance frequency.

In Fig. 9 and embodiment shown in Figure 11, each embodiment has constructed the self-vibration loop of a use piezoelectric oscillator, and this is a kind of application that reduces the capacitive component loop that comprises damping capacitor Cd (or Cd ') and electrostatic capacitance Cs.

The actual electrical sub-element of realization electrostatic capacitance Cs can be made with the same material that constitutes piezoelectric oscillator 1.A part that constitutes the material of the piezoelectric oscillator processing that can not polarize, a part can be used as electrostatic capacitance Cs like this.In addition, amplifier 27,31st, the device of amplification voltage, multiplying arrangement can be by transistor, compositions such as operational amplifier, transformer.

Figure 13 represents drive unit according to still another embodiment of the invention, and this drive unit can be followed the tracks of the tuning-points of piezoelectric oscillator.

Referring to Figure 13, an electrode grounding of piezoelectric oscillator 2, and driving voltage V is added on another electrode (opposite side) of piezoelectric oscillator 2.On a C, driving voltage is added on another electrode, and the amplifier 7 that gains to (N+1) is connected on the C point.The electrostatic capacitance Cs that connects with the amplification output terminal of this amplifier 7 is connected on the C point, thereby constitutes loop 8 (reducing the capacitive component loop).Configuration aspects is identical with loop shown in Figure 1

Referring to Figure 13, the supplying electric current of piezoelectric oscillator 2 is represented with i, the electric current that flows through electrostatic capacitance Cs is represented with i1, the impedance of piezoelectric oscillator 2 series resonance sides 3 is represented with Zm, the electric current that flows through this series resonance side represents with i2, and the electric current that flows through damping capacitor Cd is represented with i3 and the electric current that flows through amplifier 7 is represented with i4.

When voltage V was added on the C, because the effect of amplifier 7, the voltage at some D place was (N+1) V.Like this, the voltage that equals NV is added in (D-C) between a D and the C.Because the impedance at D-C place is 1/ (j ω Cs), i1 can represent with formula 31.

(formula 31) i1=j ω CsNV

Similarly, i2 and i3 can represent with formula 32 and formula 33.

(formula 32) i2=V/Zm

(formula 33) i3=j ω CdV

If because i4 is very little, can ignore, then i can represent with formula 34.

(formula 34) i=i2+i3-i1

In formula 31,32 and 33 substitution formulas 34, can get formula 35.

(formula 35) i=V/Zm+j ω (Cd-NCs) V

Here, if formula 36 establishments.

(formula 36) Cs=Cd/Ni will equal the right-hand vector of formula 32, and i equals i2.In other words, the supplying electric current that is supplied to piezoelectric oscillator 2 only considers to flow into the amount of the impedance Z m of series resonance side 3, and does not have current supply to damping capacitor Cd, and damping capacitor Cd does not exert an influence to vibration.

Then, the gain characteristic of supplying electric current i represents that with formula 37 tuning-points represents that with formula 38 phase propetry is represented with formula 39.Figure 14 A represents the frequency characteristic of supplying electric current i gain, and Figure 14 B represents the frequency characteristic of supplying electric current i phase place.

(formula 37) i=V/Zm=V/{Rm+j (ω Lm-1/ ω Cm) }

$=V\&CenterDot;{\mathrm{\&epsiv;}}^{\mathrm{j\&theta;}}/\left[\sqrt{{\mathrm{<figure-callout\; id="2"\; label="Rm"\; filenames="A9610040200411.png"\; state="\{\{state\}\}">Rm</figure-callout>}}^2+{(\mathrm{\&omega;Lm}-1/\mathrm{\&omega;Cm})}^2}\right\}]$

(formula 38) $\mathrm{fa}=1/\left\{2\mathrm{\&pi;}\sqrt{(\mathrm{Lm}\&CenterDot;\mathrm{Cm})}\right\}$

(formula 39) θ=-tan ^-1{ (ω Lm-1/ ω Cm)/Rm}

Referring to Figure 14 B, the phase place of the supplying electric current of piezoelectric oscillator 2 and the phase differential that is added between the phase place of the driving voltage on another electrode of piezoelectric oscillator 2 are 0 degree at tuning-points fa place.The represented embodiment of Figure 13 is directed to this with notice and in fact invents.Like this, can obtain to follow the tracks of the drive unit of wiping the piezoelectric oscillator a little that shakes by detecting this phase differential.

Referring to Figure 13, the AC power source part of drive pressure electrical oscillator 2 comprises again: current phase pick-up unit, Waveform forming device A, Waveform forming device B, phase comparator, loop filter, voltage-controlled oscillator (VCO) and power amplifier.

The current phase that partly is supplied to another electrode of piezoelectric oscillator 2 from the AC power supply source detects with the electric current phase detection device.In Waveform forming device A, represent with φ 1, represent with φ 2 and be added in the output that voltage-phase on the piezoelectric oscillator 2 passes through after the Waveform forming device B wave shaping through the output of wave shaping.Through two inputs that output is phase comparator after the wave shaping, can detect the phase error of φ 1 and φ 2 like this.Send into loop filter (low-pass filter) by the phase error output that phase comparator comes, the high fdrequency component of output is removed, thereby obtain phase error voltage Vp.This phase error voltage Vp input voltage control generator (VCO), the frequency that the result can obtain adapting with Vp is exported.After this, power amplification is carried out in the output of VCO in power amplifier, be added on the piezoelectric oscillator 2 by the current phase pick-up unit then.

Here, phase comparator, loop filter and voltage-controlled oscillator (VCO) are work like this, and promptly when the phase place (voltage-phase) of phase place (current phase) the specific output φ 2 that exports φ 1 was further leading, the oscillation frequency of voltage-controlled oscillator became than higher.On the contrary, phase comparator, loop filter and voltage-controlled oscillator are worked like this, and promptly when the phase place (current phase) of phase place (voltage-phase) the specific output φ 1 that exports φ 2 was more leading, then the oscillation frequency of voltage-controlled oscillator became lower.When the phase place of output φ 1 the same with the phase place of exporting φ 2, promptly when the phase differential between current phase and the voltage-phase be 0 when spending, oscillation frequency is fixed.As shown in Figure 14B, export the phase place of φ 2 when identical when phase place and the voltage of electric current output φ 1, piezoelectric oscillator 2 will be driven at the tuning-points place.When the resonant frequency point of piezoelectric oscillator reduces owing to influences such as external environment conditions, φ 2 and φ 1 relatively, phase place becomes in advance, and the frequency of voltage-controlled oscillator is variable control when hanging down numerical value, can follow the tracks of resonance like this.On the contrary, when the resonance frequency of piezoelectric oscillator uprised, φ 1 and φ 2 compared, and phase place becomes in advance, and the frequency gets higher of voltage-controlled oscillator, can follow the tracks of resonance like this.

In drive unit shown in Figure 13, there is no need provide the sensor that detects resonance frequency, and the driving frequency of piezoelectric oscillator can be fixed on the resonance frequency of piezoelectric oscillator as in the common example.Realize that by the present invention structural drawing shown in Figure 13 is very effective, particularly when because space or resulting cost performance impact, in the time of can not adding this sensor.In addition, even ought be owing to the influence of the heat that produces, when tuning-points changed inadequately, resonance frequency can be automatically tracked.Moreover the loop of being realized by the present invention can be used for the piezoelectric oscillator of form of ownership.Like this, this loop goes for the drive unit of piezo-electric motor, piezoelectric transducer and piezolectric gyroscope, even make because temperature variation etc. when causing the resonance frequency of piezoelectric oscillator to change, can often be followed the tracks of resonance frequency.

In other words, in drive unit shown in Figure 13, possess loop 8 (reducing the capacitive component loop) and eliminated the power consumption that the damping capacitor Cd by piezoelectric oscillator 2 causes, and realized following the tracks of the driving operation of the resonance of piezoelectric oscillator 2.

Here, the actual electrical sub-element of realizing electrostatic capacitance Cs can be made with the same material that constitutes piezoelectric oscillator 2.A part that constitutes the material of piezoelectric oscillator 2 is made the part of not handling through hyperpolarization, and therefore, this part can be used as electrostatic capacitance Cs.Amplifier is the device that is used to amplify voltage, and amplifier 7 can be made of transistor, operational amplifier, transformer etc.

Figure 15 represents pick-up unit according to still another embodiment of the invention.

Referring to equivalent circuit shown in Figure 15, piezoelectric oscillator 50 utilizes electric loop to represent like this, promptly when piezoelectric oscillator is accepted external stress, just produces voltage.Figure 15 is the equivalent circuit of pick-up unit, wherein, is for example given the vibration of piezoelectric oscillator by compound centripetal force, is detected in the oscillation mode gyroscope.In the equivalent circuit of Figure 15, represent to produce mechanical stress with the part that F represents, this mechanical stress is converted to electric signal by the converter of equivalence.Cd2 in the part of representing with E in same equivalent circuit represents damping capacitor, and it is a capacitive component as the non-conductive material of piezoelectric.

An electrode grounding of piezoelectric oscillator 50, and have gain on the amplifier 57 of (N+1) and another electrode (opposite side of oscillator) that electrostatic capacitance Cs2 is connected on piezoelectric oscillator 50.Like this, constituted a loop similar 58 (reducing the capacitive component loop) to loop shown in Figure 1.In other words, in this pick-up unit, constituting the amplifier 57 that reduces the capacitive component loop will be in the voltage amplification of G point generation.

Referring to Figure 15, represent with i10 that still the electric current that flows through electrostatic capacitance Cs2 represents that with i11 the electric current that flows through damping capacitor Cd2 is represented with i13, extracts out as the electric current of output and represents with i12 by the electric current that extraneous stress produces.Because the electric current of input amplifier 57 is very little, can ignore this electric current.

If represent with V that at the voltage that a side of the electrode of piezoelectric oscillator 50 produces the voltage of ordering at H is (N+1) V, quantity is that the voltage of NV is added in (H-G) between a H and the G.Impedance between the some H-G is 1/ (j ω Cs2), and therefore, i11 can represent with formula 40.

(formula 40) i11=j ω Cs2NV

Voltage V is added on the damping capacitor Cd2, and therefore, i13 can represent with formula 41.

(formula 41) i13=j ω Cd2V

When setting up the concerning of formula 42, formula 43 is set up.

(formula 42) Cs2=Cd2/N

(formula 43) i13=i11

Here, the pass of formula 44 ties up to the G point and sets up, and formula 43 substitution formulas 44 can be got formula 45.

(formula 44) i11+i10=i13+i12

(formula 45) i12=i10

Correspondingly, if electrostatic capacitance Cs2 is the 1/N of damping capacitor Cd2, then electric current 58 is supplied to damping capacitor Cd2 from the loop.As a result, because the influence of the electric charge that external carbuncle produces, the current i 10 that is produced is not supplied to damping capacitor Cd2, and current i 10 can all outwards be extracted out like this.This state is represented with the equivalent circuit 51 of Figure 16.Compare with the situation that has damping capacitor Cd2, very clear, output impedance Z increases, and as sensor, output sensitivity improves simultaneously.

In this pick-up unit, flow through condition that the current i 13 of damping capacitor Cd2 is cancelled for satisfying formula 42, provide and this condition is a function by the gain N of electrostatic capacitance Cs2 and amplifier 57, and do not comprise the function that detects electric voltage frequency.Therefore, the dependence of frequency is not included in the condition of offsetting damping capacitor Cd2.Because in the process of offsetting damping capacitor Cd2, it is more much easier than adjusting inductance L to adjust electrostatic capacitance Cs2.By using the variable electrostatic capacitance of varactor or vernier capacitor formula, can make compact conformation simultaneously.Perhaps, if the gain N of amplifier 57 can regulate with variable resistor, and electrostatic capacitance Cs2 fixes, and also can obtain similar superior effect, like this, can make structure further compact.

Certainly, also can obtain superior effect, even the condition coupling that the electrostatic capacitance Cs2 that Here it is will connect can not be well sets with aforementioned formula 42, the influence of damping capacitor Cd2 also can reduce.In addition, the actual electrical sub-element of realizing electrostatic capacitance Cs2 can be used the same made that constitutes piezoelectric oscillator.Perhaps, in oscillation mode gyroscope etc., have only the processing that can not polarize of the part of the piezoelectric of the test section that constitutes piezoelectric oscillator, this part also can be used as electrostatic capacitance Cs2.Perhaps, when whole piezoelectrics of piezoelectric oscillator are handled through hyperpolarization, and the part of not vibrated in this piezoelectric also can be used as electrostatic capacitance Cs2.In addition, amplifier 57 is for amplifying the device of voltage, and this device can be made of transistor, operational amplifier, transformer etc.

Figure 18 and Figure 20 represent the experimental result of relevant pick-up unit of the present invention shown in Figure 15.

Adopted component parts 10 as shown in Figure 8 in the experiment.

Figure 18 represents the experimental result of common pick-up unit, and this pick-up unit does not use loop 58 of the present invention (reducing the capacitive component loop).In experimental provision, the drive electrode 11 of component parts 10 shown in Figure 8, electrode 13, detecting electrode 17 and electrode 15 are connected to the terminal A of experimental loop shown in Figure 17, and terminal B is on terminal C and the terminal D.Terminal B shown in Figure 17 and terminal D ground connection.Driving voltage is by AC driving power source 5, and drive electrode 11 and electrode 13 by Fig. 8 are supplied on the piezoelectric 12, and like this, piezoelectric can carry out the bending vibration.Then, detect the vibration that passes to piezoelectric 16 by glass substrate 14.Piezoelectric oscillator 50 shown in Figure 15 equivalent circuit is corresponding to this piezoelectric 16 of Fig. 8.

Figure 18 is illustrated in the output voltage V out of (C-D) between the terminal C and terminal D shown in Figure 17.Figure 18 is a figure, and its abscissa axis is represented frequency, and its axis of ordinates is represented output voltage V out (dB), and fc is illustrated in the peak response in the testing process.

Figure 20 has represented to use the experimental result of loop 58 of the present invention (reducing the capacitive component loop).In this experimental provision, terminal B and terminal D ground connection, and terminal A is connected with AC driving power source 5, as shown in figure 19.Loop 58 (reducing the capacitive component loop) is connected on the terminal C, and the amplifier 57 that has gain (N+1) in this loop is connected with electrostatic capacitance Cs2.The amplification coefficient that comprises the negative feedback channel 56 setting amplifiers 57 of resistance R 3 and R4.The electrode 11,13,17 and 15 of component parts shown in Figure 8 respectively with terminal A, B, C is connected with D.In addition, in Figure 19, piezoelectric 16 is corresponding to piezoelectric oscillator 50.

Driving voltage is by AC driving power source 5, and drive electrode 11 and electrode 13 by Fig. 8 are supplied to piezoelectric 12, and like this, piezoelectric carries out the bending vibration.Yet, detect the vibration that is passed to piezoelectric 16 by glass substrate 14.Figure 20 represents the output voltage V out between experimental provision terminal C shown in Figure 19 and the terminal D (C-D).Figure 20 is a figure, and its abscissa axis is represented frequency, and its axis of ordinates is represented output voltage V out (dB).In Figure 19, amplifier 57 is an operational amplifier, and (R3, R4 Cs2) set according to formula 46 and formula 47 each parameter.

(formula 46) N+1=1+R3/R4

(formula 47) Cs2=Cd2/N

Relatively the output voltage V out at Figure 18 and Figure 20 point fc place as can be seen, shown in Figure 20 have a loop 58 (reducing the capacitive component loop), satisfy the common device high approximately 5dB of the output voltage of the device that formula 47 imposes a condition than Figure 18, therefore, can reach highly sensitive detection, make the influence of resistance chip capacitor Cd2 reduce to minimum.

Will the improvement example of the foregoing description be described below.

At first, in the embodiment shown in fig. 1, constructed loop 8, in this loop, had amplification coefficient and connect with electrostatic capacitance Cs for the amplifier 7 of (N+1), this loop is a capacitive component loop.Yet this reduces the capacitive component loop and also can construct like that as shown in figure 21.

Referring to Figure 21, be provided with a passage among the figure, driving power is supplied on the electrode of piezoelectric oscillator 2 one sides (some C ') by this passage from AC driving power source 5, and be provided with another passage, this passage comes out from above-mentioned channel branch, amplifier 7 and electrostatic capacitance Cs series connection in this passage, and electrostatic capacitance Cs is connected on the C ' point.In other words, the passage (a) of supply driving power is in parallel with the passage (b) that another has amplifier 7 and electrostatic capacitance Cs between driving power (AC driving power source 5) side and piezoelectric oscillator 2.In addition, in this embodiment, the driving voltage V that is supplied to piezoelectric oscillator 2 described sides is gone into big device and is amplified (N+1) doubly, and the amplification output terminal of amplifier 7, is connected on the C ' point by electrostatic capacitance Cs.

Figure 21 represents the piezoelectric oscillator with same form shown in Figure 1.When the electric current that is supplied to a C ' by AC driving power source 5 is represented with i, the electric current that flows through series resonance side and damping capacitor Cd is represented with i2 and i3 respectively, when flowing through the electric current i1 ' expression of electrostatic capacitance Cs, then the relation between each electric current will be the relation that the i1 in formula 9 is drawn by i1 ' replacement.

Therefore, in the drive unit that is equipped with minimizing capacitive component loop 8 ' shown in Figure 21, condition when formula 11 expressions, be that electrostatic capacitance Cs is that the condition of the 1/N of damping capacitor Cd is when satisfying, damping capacitor Cd does not consume from the next supplying electric current i of driving power, like this, piezoelectric oscillator can be driven effectively.

In addition, in the embodiment shown in fig. 13, even, also can obtain same superior effect if loop 8 is replaced by the capacitive component loop 8 ' that reduces shown in Figure 21.

Figure 22 represents the drive unit of piezoelectric oscillator shown in Figure 21 is carried out improved better example.Referring to Figure 22, driving power is in parallel with passage (b) by the passage (a) that it is supplied to electrode in piezoelectric oscillator 2 one sides (some C '), and passage (b) has the amplifier 7 and the electrostatic capacitance Cs of mutual series connection between as driving power supply side and the electrode (putting C ') in described side.In other words, passage (a) and passage (b) constitute with bifurcation approach, passage (a) partly is supplied to piezoelectric oscillator 2 with power from the supply of driving power, and passage (b) is by amplifier 7 and electrostatic capacitance Cs, constitute to piezoelectric oscillator 2 from the supply part of driving power, formation reduces capacitive component loop 8 ".With power supply to the passage (a) of piezoelectric oscillator 2, be provided with voltage-tracing device (buffer amplifier) 41, as voltage retaining device.

Voltage-tracing device 41 is electric parts that the people that are skilled in technique know usually, the wherein outgoing side of operational amplifier and reversible input side short circuit, and adopt 100% feedback, like this, voltage gain is set at i.Voltage-tracing device 41 works to keep driving power voltage and prevents to produce vibration.In other words, in loop structure shown in Figure 1, with gain amplifier set the too high voltage amplification that can order C, and in loop 8, may produce vibration, because loop 8 is a feedback-type, wherein electric weight feeds back to a C by electrostatic capacitance Cs, produces non-steady state like this.Yet the voltage-tracing device 41 that is provided with as shown in figure 22 can prevent to form oscillation circuit in passage (a) and passage (b), can constitute the highly stable drive unit of piezoelectric oscillator like this.

Figure 23 represents an example, comprising the capacitive component loop 8 that reduces shown in Figure 22 " structure be used in the resonant tracking drive unit shown in Figure 13.To in the past similar with the explanation that Figure 14 is done according to Figure 13, the current phase of supplying with from the power amplifier of supplying with part (supply side) as driving power is detected by the current phase pick-up unit, and its (current phase) output φ 1 delivers to phase comparator.The voltage of C ' point promptly is supplied to the voltage-phase of piezoelectric oscillator 2, delivers to phase comparator as output 42.Then, voltage-controlled oscillator (VCO) is controlled like this, if promptly the phase differential of exporting between φ 1 and the φ 2 is 0, then oscillation frequency is fixed.Therefore, the driving operation of tracking piezoelectric oscillator 2 tuning-pointss becomes possibility.

Among Fig. 1, represented piezoelectric oscillator as the electrostatic sensor device.Same superior effect can reach in the drive unit of electrostatic transducer 60, shown in Figure 24 A.

Referring to Figure 24 A, in electrostatic transducer 60, be placed on the opposite of the flat electrodes 62 of movable side in the flat electrodes 61 of fixation side, a little gap d is arranged in the middle of their.When electrode 61 and 62 aspectant areas are represented with A, the bias voltage that provides between the electrode is represented with E, the input voltage that provides between the electrode (driving voltage) represent with V and electrode between the specific inductive capacity of air layer when representing with ε, then owing to the influence of input voltage V, the static driven power f that acts between electrode 61 and 62 is represented by formula 48.

(formula 48) f={ (ε AE)/d ²V

Near electrostatic transducer 60 driven equivalent circuit tuning-points is shown among Figure 24 B with 60a (sees the part that indicates reference number 60a).Near the state that this and piezoelectric oscillator shown in Figure 1 vibrate tuning-points is of equal value.Referring to Figure 24 B, Ca represents the capacitive component between electrode 61 and 62, and R represents the mechanical drive resistance of movable electrode 62, and L represents the spring constant by the movable electrode of mechanical support generation, and C represents the viscous resistance by mechanical elasticity supporting generation.In the process that drives electrostatic transducer 60a, capacitive component Ca also consumes drive current, and this current drain is inoperative to the driving operation of movable electrode 62.

Therefore, added (the perhaps more complete capacitive component loop 8 ") that reduces that reduces capacitive component loop 8 ' or Figure 22 of Figure 21; shown in Figure 24 A and Figure 24 B; make that electrostatic capacitance Cs is the 1/N of capacitive component Ca, and the enlargement factor of amplifier 7 is set at (N+1), the loop 8 identical with the loop of Fig. 1.Like this, utilize the mode similar, can make on capacitive component Ca consumed current reduce to minimum, and and then offset to the drive unit of piezoelectric oscillator.The result can reach effective driving operation.In this case, use comprise voltage-tracing device 41 shown in Figure 22 reduce capacitive component loop 8 ", can carry out stable driving operation, can not produce vibration.

Their wiring diagram and advantage are the same with the wiring diagram and the advantage of drive unit shown in Figure 13, and simultaneously, the resonant tracking drive unit of Figure 13 and the resonant tracking drive unit of Figure 23 go for electrostatic transducer 60.

Secondly, Figure 25 A represents to utilize electrostatic transducer 60 to detect the pick-up unit of vibration.For example, in the oscillation mode gyroscope, pick-up unit works like this, and promptly piezoelectric oscillator etc. makes movable electrode 62 vibrations, and the masterpiece that compound centripetal force produces is used on this movable electrode 62.

When because the movement velocity of the movable electrode 62 that the effect of the power of generations such as compound centripetal force causes when representing with V, the detection current i can be represented with formula 49.

(formula 49) i={ (ε AE)/d ²V

Extract this current i out, can draw output voltage V out.

In this pick-up unit, detect output and reduce a size of current value that flows through the capacitive component Ca of electrostatic transducer 60, shown in the equivalent circuit of Figure 25 B.Yet, similar to pick-up unit shown in Figure 15, added loop 58 (reducing the capacitive component loop), wherein amplifier 57 has the amplification coefficient of (N+1), and the capacitance of electrostatic capacitance Cs2 is set at the 1/N of capacitive component Ca.Therefore, similar to embodiment shown in Figure 15, the electric current that flows through capacitive component Ca is by 58 electric current has strengthened from the loop, and the result can detect highly delicately by the resulting electric current of machinery-electric conversion.

In addition, in Fig. 9 and self-vibration loop shown in Figure 11, can replace piezoelectric oscillators with electrostatic transducer 60 when building the loop.In other words, when electrostatic transducer 60 is driven when doing self-vibration, can use the self-vibration loop 20 same near tuning-points with loop shown in Figure 9.Because electrostatic transducer 60 uses capacitive component Ca, antiresonance point has appearred.Near the equivalent circuit that electrostatic transducer 60 vibrates antiresonance point is identical with the form shown in Figure 12 A.Therefore, use self-vibration loop 30 shown in Figure 11, electrostatic transducer 60 can be driven near antiresonance point, does self-vibration.

As mentioned above, use when of the present invention, the capacitive component loop of being made up of electrostatic capacitance and amplifier that reduces is connected on the side (electrode) such as the electrostatic sensor device of piezoelectric oscillator and electrostatic transducer one class.Like this, can be supplied to piezoelectric oscillator with the electric current of the electric current equivalence of damping capacitor component that flows through piezoelectric oscillator etc., and be used for the damping capacitor that piezoelectric oscillator inputs or outputs, or the capacitive component of electrostatic transducer can be cancelled of equal valuely or reduce to minimum.

Therefore, when on the driving loop that is used in the electrostatic sensor device, can not use inductance just can offset damping capacitor or capacitive component.Like this, can not rely on frequency, the loop adjustment easily and size can do compactly.Even under the situation that the condition of offsetting can not satisfy well of equal valuely, capacitive component also can be reduced by equivalence effectively.In addition, in reducing the capacitive component loop, have such as the such voltage retaining device of voltage-tracing device and can reach more stable driving operation.

In addition, in the time of on being used in such as the pick-up unit of piezolectric gyroscope one class, output impedance will increase.Like this, the output voltage increase can improve detection sensitivity.In the time of on being used for piezoelectric transducer, can obtain similar superior effect.So the output voltage increase can be made contributions to the performance of improving converter.

In addition, when being used for wave filter, offset or the damping capacitor that reduces piezoelectric oscillator can increase the comparison bandwidth.

Moreover, according to the present invention, reduce the capacitive component loop and be connected on the electrostatic sensor device, and tuning-points can obtain like this, the voltage-phase that is about to flow into the current phase of piezoelectric oscillator etc. and drive pressure electrical oscillator etc. compares.So, device just can be driven at the tuning-points place that obtains like this, like this, even when causing the tuning-points of electrostatic sensor device to fluctuate owing to reasons such as temperature, also can often follow the tracks of tuning-points.As a result, can not utilize sensor, only utilize the sensing device that is located on fraction of piezo-electric motor, under common condition of work, just can reach the tracking operation that has realized.Therefore, loop of the present invention is not only applicable to the piezo-electric motor of all models formula, and can be used as frequency-tracking formula driving loop use, such as the piezoelectric sensor and the piezoelectric transducer that are used to use other piezoelectric effects.

In addition, utilize amplifier and frequency to select the loop to constitute the self-vibration loop, and near the capacitive component of the electrostatic sensor device that vibrates tuning-points or antiresonance point and resistive component are included in this frequency and select in the loop.Like this, the electrostatic sensor device can be driven near tuning-points or antiresonance point, thereby realizes effectively driving operation.In addition, having additional capacitor and additional resistance makes and might carry out self-vibration at the frequency place consistent or approaching with the tuning-points of electrostatic sensor device or antiresonance point.

In addition, in the negative loop of amplifier, comprise the resistance that can make amplification coefficient be set at high numerical value, may under stabilized amplitude, carry out self-vibration like this.

Except already mentioned above, also can do many improvement and variation to the foregoing description, and can not depart from novelty of the present invention and superior characteristics.Correspondingly, all these improvements and changes can be included in the appending claims scope.

Claims (23)

1. loop that reduces capacitive component in the electrostatic sensor device, it is characterized in that: it has an amplifier, amplifier is with the voltage amplification of electrostatic sensor device one side, it also has a passage simultaneously, this passage is from the amplification output terminal of amplifier, be connected with the described side of electrostatic sensor device by electrostatic capacitance, like this, it is minimum that the capacitive component of electrostatic sensor device can reduce to.

2. reduce the capacitive component loop in the described electrostatic sensor device of claim 1, wherein the electrostatic sensor device comprises a piezoelectric oscillator, and electrostatic capacitance is to use and constitutes that piezoelectric vibration modulator material identical materials realizes.

3. reduce the capacitive component loop in the described electrostatic sensor device of claim 1, wherein the enlargement factor of amplifier is approximately the capacitive component of electrostatic sensor device (N+1) doubly, and electrostatic capacitance is approximately the 1/N of electrostatic sensor device capacitive component.

4. reduce the capacitive component loop in the described electrostatic sensor device of claim 3, wherein the electrostatic sensor device comprises a piezoelectric oscillator, and electrostatic capacitance realizes by using with the same material that constitutes piezoelectric oscillator.

5. the drive unit of an electrostatic sensor device, it comprises:

, a passage, driving power is supplied to electrostatic sensor device and a loop that reduces capacitive component by this passage; In this loop, be provided with amplifier, amplifier is with the voltage amplification of electrostatic sensor device one side, this loop also is provided with a passage simultaneously, this passage is from the amplification output terminal of amplifier, be connected with the described side of electrostatic sensor device by electrostatic capacitance, thereby make the capacitive component of electrostatic sensor device reduce to minimum.

Wherein, the amplifier in reducing the capacitive component loop is arranged on such position, promptly is supplied to the driving power of electrostatic sensor device, is exaggerated by described passage.

6. the drive unit of the described electrostatic sensor device of claim 5, wherein the electrostatic sensor device comprises a piezoelectric oscillator, electrostatic capacitance is by using and constituting piezoelectric vibration modulator material identical materials and realize simultaneously.

7. the drive unit of the described electrostatic sensor device of claim 5, wherein the enlargement factor of amplifier be approximately electrostatic sensor device capacitive component (N+1) doubly, and electrostatic capacitance is approximately the 1/N of electrostatic sensor device capacitive component.

8. the drive unit of the described electrostatic sensor device of claim 5, wherein, the electrostatic sensor device comprises a piezoelectric oscillator, and electrostatic capacitance is by using and constituting piezoelectric vibration modulator material identical materials and realize.

9. the drive unit of the described electrostatic sensor device of claim 5, also comprise: the current phase pick-up unit is used to detect the current phase that flows through the electrostatic sensor device; Phase comparator is used for comparison by described current phase pick-up unit current phase that detects and the voltage-phase that is supplied to the driving power of electrostatic sensor device; Wave filter, the high fdrequency component of the described phase comparator of its elimination; Voltage-controlled oscillator, it comes variable control oscillation frequency according to the output voltage that obtains after the filtering operation that is undertaken by described wave filter, thereby can supply with driving power according to the oscillation frequency of described voltage-controlled oscillator, and the electrostatic sensor device is driven at the resonance frequency place.

10. the drive unit of the described electrostatic sensor device of claim 5, wherein, the electrostatic sensor device comprises a piezoelectric oscillator, and the oscillation frequency of described voltage-controlled oscillator is variable like this control, promptly by described phase comparator relatively, the phase differential between current phase and the voltage-phase is zero.

11. the drive unit of the described electrostatic sensor device of claim 5, wherein, be supplied to the described passage of electrostatic sensor device and comprise between the amplifier supply side and electrostatic sensor device that is located at driving power in parallel by its driving power with the passage of electrostatic capacitance, wherein, voltage retaining device is located at driving power and is supplied in the described passage of electrostatic sensor device by it.

12. the drive unit of the described electrostatic sensor device of claim 11 also comprises: the current phase pick-up unit is used to detect the current phase that flows through the electrostatic sensor device; Phase comparator is used for comparison by described current phase pick-up unit current phase that detects and the voltage-phase that is supplied to the driving power of electrostatic sensor device; Wave filter, the high fdrequency component of the described phase comparator of its elimination; Voltage-controlled oscillator, it is according to the variable control oscillation frequency of output voltage that is obtained behind filtering operation by described wave filter, thereby can supply with driving power according to the oscillation frequency of described voltage-controlled oscillator, the electrostatic sensor device is driven at the resonance frequency place.

13. the drive unit of the described electrostatic sensor device of claim 12, wherein, the electrostatic sensor device comprises a piezoelectric oscillator, the oscillation frequency of described voltage-controlled oscillator is variable like this control simultaneously, and promptly the phase differential by the more ferroelectric stream phase place of described phase comparator current potential phasetophase is zero.

14. the pick-up unit of an electrostatic sensor device, it comprises:

Amplifier, it is with the voltage amplification of electrostatic sensor device one side; , a passage, it is connected with the described side of electrostatic sensor device by electrostatic capacitance from the amplification output terminal of described amplifier; Reduce the capacitive component loop, it makes the capacitive component of electrostatic sensor device reduce to minimum.

15. the pick-up unit of the described electrostatic sensor device of claim 14, wherein, the electrostatic sensor device comprises a piezoelectric oscillator, and electrostatic capacitance is to realize by using with the material identical materials that constitutes piezoelectric oscillator simultaneously.

16. the drive unit of the described electrostatic sensor device of claim 14, wherein, (N+1) that the enlargement factor of amplifier is approximately electrostatic sensor device capacitive component doubly, and electrostatic capacitance is approximately the 1/N of electrostatic sensor device capacitive component.

17. the pick-up unit of the described electrostatic sensor device of claim 16, wherein, the electrostatic sensor device comprises a piezoelectric oscillator, and electrostatic capacitance realizes by using and constituting the same material of piezoelectric vibration modulator material.

18. the drive unit of electrostatic sensor device, it comprises:

Frequency is selected the loop, and it comprises the capacitive component and the resistive component of electrostatic sensor device; Amplifier, it comprises the described frequency selection loop that is located in the positive feedback loop; Like this, self-vibration selects the frequency place of loop decision to carry out in described frequency.

19. the drive unit of the described electrostatic sensor device of claim 18 wherein, is provided with the amplitude stability loop in the negative feedback loop of described amplifier, this loop comprises the resistance of a described amplifier amplification coefficient of decision.

20. the drive unit of the described electrostatic sensor device of claim 18, wherein, described frequency selects the loop by first resistance of connecting in the positive feedback loop of described amplifier and first electric capacity, and also remove and second resistance that is connected with the irreversible input side of described amplifier and second electric capacity and form, wherein, first resistance and first electric capacity, or the capacitive component and the resistive component of second resistance and second electric capacity and electrostatic sensor device adapt.

21. the drive unit of the described electrostatic sensor device of claim 20 wherein, is provided with the amplitude stability loop in the negative feedback loop of described amplifier, this loop comprises the resistance of a described amplifier amplification coefficient of decision.

22. the drive unit of the described electrostatic sensor device of claim 20, wherein, additional capacitor is connected with the electrostatic sensor device with additional resistance.

23. the drive unit of the described electrostatic sensor device of claim 22 wherein, is provided with the amplitude stability loop in the negative feedback loop of described amplifier, this loop comprises the resistance of a described amplifier amplification coefficient of decision.

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