JPH0933334A - Impedance characteristic measuring method for piezoelectric component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the impedance of a piezoelectric component without waste and with superior precision and quickness by sampling frequencies at a smaller frequency pitch as approaching the frequency of a phase of zero degree. SOLUTION: A frequency region containing a frequency in which the phase of a piezoelectric component becomes zero degree is sampled at a frequency pitch Δfs , and sampling frequencies f1 , f2 , which are the frequencies before and after first passing a phase of zero degree, and their phases ϕ1 , ϕ2 are measured, and sampling frequencies f3 , f4 , which are the frequencies before and after once more passing the phase of zero degree, and their phases ϕ3 , ϕ4 are measured. By an interpolation method, a temporary resonance frequency fr1 and an temporary anti-resonance frequency fa1 are led out, and when phases ϕ5 , ϕ6 measured at the frequencies fr1 , fa1 stay within a predetermined phase cross, the frequencies fr1 , fa1 are determined as the resonance frequency (measured value) and the anti-resonance frequency (measured values), and also the impedance is measured at the frequencies fr1 , fa1 so as to obtain a resonance impedance Zr and an anti-resonance impedance Za respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring impedance characteristics of a piezoelectric component, particularly a piezoelectric component used in an oscillation circuit, a resonance circuit or the like.

[0002]

Conventionally, the resonance frequency f _r of the piezoelectric ceramic resonator, the anti-resonance frequency f _a, when measuring the resonance impedance Z _r and antiresonant impedance Z _a is a resonant frequency f _r and the antiresonance frequency f _a The resonance frequency f _r , the anti-resonance frequency f _a , the resonance impedance Z _r, and the anti-resonance impedance Z _a are obtained by sampling the included frequency region at a constant frequency pitch and examining the impedance values obtained by each sampling. .

[0003]

However, in the conventional method, since the frequency domain is sampled at a constant frequency pitch, it takes a long time for measurement, and the measurement is wasteful. This is because the impedance values that are actually required are only those near the resonance frequency f _r and the anti-resonance frequency f _a , and the remaining measurement data are hardly needed.

Therefore, an object of the present invention is to provide a method for measuring the impedance characteristic of a piezoelectric component, which can improve the measurement efficiency and easily improve the measurement accuracy.

[0005]

In order to achieve the above object, the method for measuring the impedance characteristic of a piezoelectric component according to the present invention comprises (a) a frequency at which the phase of the piezoelectric component becomes 0 ° at a predetermined frequency pitch Δf _S. And sampling the frequency region including 0, and measuring the sampling frequency f ₁ and its phase φ ₁ before passing the phase 0 °, and the sampling frequency f ₂ and its phase φ ₂ after passing the phase 0 °,
(B) a step of deriving the equation _{f 3 = f 1 + (Δf} S · φ 1) / (φ 1 -φ 2) frequency f ₃ using a piezoelectric component in (c) the frequency f ₃ Impedance And the step of measuring
It is characterized by having.

[0006] The impedance characteristic measuring method of a piezoelectric component according to the present invention, (d) a piezoelectric component of the resonant frequency f _r
And _a frequency pitch Δf _S slightly smaller than the difference Δf between the antiresonance frequency f _{a and} the frequency range including the frequency at which the phase of the piezoelectric component becomes 0 °, are sequentially sampled from the low frequency side, and before the phase 0 ° is passed first. the sampling frequency f ₁ and the phase phi ₁ the first phase 0 and゜Wo sampling frequency f ₂ and the phase phi ₂ after passing again the phase 0゜Wo before passing through a sampling frequency f ₃ and the phase phi ₃ , the step of measuring the sampling frequency f ₄ and the phase φ ₄ thereof after passing the phase 0 ° again, and (e) the provisional resonance frequency f _r1 and the provisional anti-resonance frequency f _a1 are respectively _expressed by the relational expression f and deriving with _{r1 = f 1 + (Δf S} · φ 1) / (φ 2 -φ 1) f a1 = f 3 + (Δf S · φ 3) / (φ 3 -φ 4), ( f) The tentative resonance frequency f
measuring the impedance of the piezoelectric component at _r1 and the provisional anti-resonance frequency f _a1 .

[0007]

The above method utilizes the fact that the phases at the resonance frequency f _r and the anti-resonance frequency f _a are each 0 °. Then, sampling is performed with a smaller frequency pitch as the frequency approaches the phase 0 °. Therefore,
Compared with the conventional method in which unnecessary frequencies are sampled at a constant frequency pitch regardless of whether they are in the vicinity of the resonance frequency f _r and the anti-resonance frequency f _a , there is no waste and accuracy is improved. Good measurements are made quickly.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for measuring impedance characteristics of a piezoelectric component according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a graph showing an impedance curve 1 and a phase curve 2 of the piezoelectric ceramic vibrator. The impedance curve 1 and the phase curve 2 show typical values of the piezoelectric ceramic vibrator. The piezoelectric ceramic vibrator, a current flowing through the vibrator at the resonance frequency f _r is to become the maximum, the impedance is minimized. on the other hand,
At the anti-resonance frequency f _a , the current flowing in the oscillator becomes minimum and the impedance becomes maximum. The former is called resonance impedance Z _r, and the latter is called anti-resonance impedance Z _a . Further, the piezoelectric ceramic vibrator has _a phase of 0 ° at the resonance frequency _fr and the anti-resonance frequency fa.

A method for obtaining the individual resonance frequency f _r1 , anti-resonance frequency f _a1 , resonance impedance Z _r and anti-resonance impedance Z _a of the piezoelectric ceramic vibrator having the above characteristics (representative values) will be described. First, derived on the basis of a difference Δf of the piezoelectric resonant frequency (typical) of the ceramic resonator f _r and the anti-resonance frequency (typical) f _a in FIG.

Next, as shown in FIG. 2, the phase characteristics of the piezoelectric ceramic vibrator are sequentially sampled from the low frequency side at a frequency pitch Δf _S slightly smaller than Δf. The sampling area at this time is the resonance frequency (representative value) _fr.
The anti-resonant frequency includes the (typical) f _a. As a result, the frequency domain including the frequency having the phase of 0 ° is sampled. Further, it is preferable that the sampling area is approximately 2Δf _S. This is because the number of samplings is small and the measurement can be performed more quickly. However, the frequency pitch Δf _S is not limited to this, and the phase characteristics may be sampled at a frequency pitch such as 1/2 or 1/3 of Δf.

Then, the sampling frequency f ₁ before passing the phase 0 ° and its phase φ ₁ are measured first, and the sampling frequency f ₂ after passing the phase 0 ° and its phase φ ₂ are measured first. , The sampling frequency f ₃ before passing the phase 0 ° and its phase φ ₃ are measured again, and the sampling frequency f ₄ after passing the phase 0 ° and its phase φ ₄ are measured again. However, in this embodiment, since the number of samplings is reduced so that the measurement can be performed quickly, the sampling frequencies f ₂ and f ₃ become the same frequency,
The phases φ ₃ and φ ₄ also have the same numerical value.

Next, a temporary resonance frequency f _r1 and a temporary resonance frequency f _a1 are derived from the following relational expressions (1) and (2) using a method of function approximation called an interpolation method. f _r1 = f ₁ + (Δf _S · φ ₁ ) / (φ ₂ −φ ₁ ) …… (1) f _a1 = f ₃ + (Δf _S · φ ₃ ) / (φ ₃ −φ ₄ ) …… ( 2) (However, f ₁ <f ₂ <f ₃ <f ₄ , φ ₂ >0> φ ₁ , φ ₃ >
0> φ ₄ ) Next, as shown in FIG. 3, the phases φ ₅ and φ ₆ of the piezoelectric ceramic vibrator at the provisional resonance frequency f _r1 and the provisional anti-resonance frequency f _a1 are measured. If the phases φ ₅ and φ ₆ are within the predetermined phase tolerance, the provisional resonance frequency f _r1 and the provisional anti-resonance frequency f _a1 are set to the resonance frequency (measurement value) and the anti-resonance frequency (measurement value) of the piezoelectric ceramic oscillator ( (Measured value)
The impedances at these frequencies f _r1 and f _a1 are measured to obtain the resonance impedance Z _r and the anti-resonance impedance Z _a , respectively.

On the other hand, the phase φ_FiveOr φ₆At least one of
If either one is out of the specified phase tolerance, use the interpolation method.
Repeat the above process until the phase within the tolerance is obtained by using
You. For example, the provisional resonance frequency f_r1Phase φ at_FiveIs given
Out of phase tolerance and φ_FiveIf> 0,
As shown in FIG. 4, the temporary resonance frequency f_r1Starting from
Frequency pitch Δf_SFrequency pitch Δf less than 1/2_S2
To sequentially support the phase characteristics of the piezoelectric ceramic oscillator to the low frequency side.
To sample. In this embodiment, Δf_S2= (Δf _S/
2). And, before the phase 0 degree is passed first,
Sampling frequency f_FiveAnd its phase φ₇Measure and rank first
Sampling frequency f after passing through phase 0 °₆And so much
Phase φ₈To measure. However, in this embodiment, the sample
Frequency f_FiveIs a temporary resonance frequency f_r1And the phase φ_FiveAnd φ
₇Will be the same value.

Next, using the interpolation method, the provisional resonance frequency f _r2 is derived again from the following relational expression (3). _{f r2 = f 6 + (Δf} S2 · φ 8) / (φ 5 -φ 8) ...... (3) Next, to measure the phase phi ₉ of the piezoelectric ceramic vibrator at the resonance frequency f _r2 of the temporary. If the phase φ ₉ is within the predetermined phase tolerance, the provisional resonance frequency f _r2 is set as the resonance frequency (measurement value) of this piezoelectric ceramic oscillator, and the impedance at this frequency f _r2 is measured to resonate. Find the impedance Z _r .

According to the above method, sampling is performed at a smaller frequency pitch as the frequency approaches the phase 0 ° (that is, the resonance frequency and the anti-resonance frequency). Regardless of the method, the impedance characteristic can be measured with high efficiency without waste, as compared with the conventional method in which unnecessary frequencies are sampled at a constant frequency pitch.

The method for measuring the impedance characteristic of the piezoelectric component according to the present invention is not limited to the above embodiment, and can be variously modified within the scope of the gist.

[0017]

As is apparent from the above description, according to the present invention, as the frequency of the phase 0 °, that is, the resonance frequency and the anti-resonance frequency is approached, sampling is performed at a smaller frequency pitch, which is a waste. It is possible to quickly perform accurate and accurate measurement.

[Brief description of drawings]

FIG. 1 is a graph showing an impedance characteristic and a phase characteristic of a piezoelectric component for explaining an embodiment of a method for measuring an impedance characteristic of a piezoelectric component according to the present invention.

FIG. 2 is a graph for explaining a method for measuring impedance characteristics of a piezoelectric component having the characteristics shown in FIG.

FIG. 3 is a graph for explaining the impedance characteristic measuring method subsequent to FIG.

FIG. 4 is a graph for explaining the impedance characteristic measuring method following FIG.

[Explanation of symbols]

f _r … Resonance frequency f _a … Anti-resonance frequency Δf _S … Frequency pitch f ₁ , f ₂ , f ₃ , f ₄ … Sampling frequency φ ₁ , φ ₂ , φ ₃ , φ ₄ … Phase f _r1 … Temporary resonance frequency f _a1 ... provisional anti-resonance frequency

Claims (2)

[Claims] 1. A sampling frequency f ₁ before passing through a phase of 0 ° is sampled in a frequency region including a frequency at which the phase of the piezoelectric component is 0 ° at a predetermined frequency pitch Δf _S.
And its phase φ _1, and the step of measuring the sampling frequency f ₂ after passing through the phase 0 ° and its phase φ ₂ , and the relational expression f ₃ = f ₁ + (Δf _S · φ ₁ ) / (φ ₁ − process and the impedance characteristic measurement method of a piezoelectric component, characterized in that it and a step of measuring the impedance of the piezoelectric component by the frequency f ₃ to derive frequency f ₃ with phi _2). In 2. A piezoelectric component of the resonance frequency f _r and the anti-resonance frequency f slightly smaller frequency pitch than the difference Delta] f of _a Delta] f _S, successively the frequency region including the frequency of the piezoelectric component of the phase becomes 0 ° from the low-frequency side Sampling frequency f ₁ and its phase φ ₁ before passing the phase 0 °, sampling frequency f ₂ and its phase φ ₂ after passing the phase 0 ° first, and phase 0 ° again Measuring the sampling frequency f ₃ and its phase φ ₃ before passing, and the sampling frequency f ₄ and its phase φ ₄ after passing again phase 0 °, and the provisional resonance frequency f _r1 and provisional anti-resonance The frequency f _a1 is _expressed by the relational expression f _r1 = f ₁ + (Δf _S · φ ₁ ) / (φ ₂ −φ ₁ ) f _a1 = f ₃ + (Δf _S · φ ₃ ) / (φ ₃ −φ ₄ ). a step of deriving with the resonance frequency f _r1 and anti-resonance circumference of provisional the temporary Impedance characteristic measurement method of a piezoelectric component, characterized in that it comprises a step of measuring the impedance of the piezoelectric component, a several f _a1.