Method for testing piezoelectric/electrostrictive device, testing apparatus, and method for adjusting piezoelectric/electrostrictive device

• US 8,304,961 B2
• Filed: 10/15/2010
• Issued: 11/06/2012
• Est. Priority Date: 04/18/2008
• Status: Expired due to Fees

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Ohnishi, Takao, Goto, Naoki
• Primary Examiner(s): DOUGHERTY, THOMAS M
• Application Number:
  US12/905,296
• Publication Number:
  US 20110025171A1
• Time in Patent Office: 753 Days
• Field of Search: 735/79, 324/727, 427/10, 310/318
• US Class Current: 310/318
• CPC Class Codes: G01N 2291/2697 Wafer or (micro)electronic parts
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/4454 Signal recognition, e.g. specific values or portions, signal events, signatures
• CPC Class Codes: H10N 30/04 Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
• CPC Class Codes: H10N 30/06 Forming electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/2047 Membrane type
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: Y10T 29/42 Piezoelectric device making
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part

Abstract

There is provided a method for testing a piezoelectric/electrostrictive actuator, wherein the displacement of a piezoelectric/electrostrictive actuator is estimated on the basis of the relations between one or more frequency characteristic values selected from the group consisting of the heights and areas of the peaks of the resonance waveforms and the difference of the maximum and minimum of the first order or first to higher orders of the resonance frequency characteristic values of the piezoelectric/electrostrictive actuator and the k-th order (k=1 to 4) of the first or first to higher orders of resonance frequencies. According to this piezoelectric/electrostrictive actuator testing method, a piezoelectric/electrostrictive actuator can be tested with high precision without actually driving the same as a product and without being accompanied by any disassembly/breakage.

Claims

1. A method for testing a piezoelectric/electrostrictive actuator, the method including the steps of obtaining one or more frequency characteristic values of the piezoelectric/electrostrictive actuator selected from the group consisting of heights and areas of the peaks of resonance waveforms and a difference between a maximum and minimum value of a first order or first to higher orders of the resonance frequency characteristic values of the piezoelectric/electrostrictive actuator and the k-th order (k=1 to 4) of the first or first to higher orders of resonance frequencies;

and

estimating a displacement of the piezoelectric/electrostrictive actuator based on a relation between one or more of the obtained frequency characteristic values;

wherein the piezoelectric/electrostrictive actuator comprises a support portion and a vibration portion, the vibration portion having a piezoelectric/electrostrictive actuating portion disposed thereon, and the piezoelectric/electrostrictive actuating portion comprising at least one piezoelectric/electrostrictive body sandwiched between at least two electrodes.

2. The method for testing a piezoelectric/electrostrictive actuator according to claim 1, wherein the relation is a relation of dividing the one or more frequency characteristic values selected from the group consisting of the heights and areas of the peaks of the resonance waveforms and the difference of the maximum and minimum of the first order of the resonance frequency characteristic values of the piezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) of the first order of resonance frequency to estimate the displacement of the piezoelectric/electrostrictive actuator by the calculated value obtained by the division.

3. The method for testing a piezoelectric/electrostrictive actuator according to claim 1, wherein the relation is a relation of dividing a sum of the one or more frequency characteristic values selected from the group consisting of the heights and areas of the peaks of the resonance waveforms and the difference of the maximum and minimum of the first to higher orders of the resonance frequency characteristic values of the piezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) of the first order of resonance frequency to estimate the displacement of the piezoelectric/electrostrictive actuator by the calculated value obtained by the division.

4. The method for testing a piezoelectric/electrostrictive actuator according to claim 1, wherein the relation is a relation of dividing the one or more frequency characteristic values selected from the group consisting of the heights and areas of the peaks of the resonance waveforms and the difference of the maximum and minimum of the resonance frequency characteristic value for each of the resonances of the first to higher orders of the piezoelectric/electrostrictive actuator by the k-th order (k=1 to 4) of resonance frequency and obtaining the sum of the values for each of the resonances to estimate the displacement of the piezoelectric/electrostrictive actuator by the calculated value obtained by the sum.

5. The method for testing a piezoelectric/electrostrictive actuator according to claim 2, wherein the displacement of the piezoelectric/electrostrictive actuator is estimated by a value obtained by further multiplying the calculated value by the capacitance of the piezoelectric/electrostrictive actuator.

6. A method for adjusting a piezoelectric/electrostrictive actuator comprising:

estimating displacements of a plurality of piezoelectric/electrostrictive actuators according to the method for testing a piezoelectric/electrostrictive actuator of claim 1; and

trimming the piezoelectric/electrostrictive body of the piezoelectric/electrostrictive portion of at least some of the plurality of piezoelectric/electrostrictive actuators to uniformly adjust the displacement of the piezoelectric/electrostrictive actuators uniformly.

7. The method for adjusting a piezoelectric/electrostrictive actuator according to claim 6, wherein both the piezoelectric/electrostrictive body and the upper electrode of at least some of the plurality of piezoelectric/electrostrictive actuators are trimmed.