Temperature adaptive method for piezoelectric transducer

Abstract

The invention belongs to the technical field of transducers, and particularly relates to a temperature adaptability method for a transducer, and the method comprises the steps: obtaining the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 of the transducer at a target temperature before optimization; the difference value f2-f1 = delta f between the resonant frequency f1 of the transducer before optimization at the room temperature and the resonant frequency f2 of the transducer at the target temperature is calculated; and the transducer is optimized according to a preset optimization strategy, so that the difference value f3-f1 between the resonant frequency f3 of the optimized transducer at the room temperature and the resonant frequency f1 of the transducer before optimization at the room temperature is equal to-delta f. According to the method, the problem of temperature adaptability of the piezoelectric ultrasonic transducer is solved, the conductivity characteristic of the transducer is optimized, and the temperature of the transducer is improved. And the performance of the material can meet the requirement of a target temperature in a non-room-temperature environment.

Description

Technical Field

[0001] The invention belongs to the technical field of transducers, and in particular relates to a temperature adaptability method for a piezoelectric transducer. Background Art

[0002] Piezoelectric ultrasonic transducer is a widely used ultrasonic transmitting and receiving device. This type of transducer uses the positive piezoelectric effect and inverse piezoelectric effect of piezoelectric materials to produce uniform vibration in the high-frequency range, similar to a rigid piston. It has the advantages of simple structure, easy excitation, easy processing and molding.

[0003] However, piezoelectric materials are temperature-sensitive components, and their resonant frequency changes with temperature, which causes the optimal operating frequency of the piezoelectric transducer to be directly affected by the working environment temperature. At present, the design of piezoelectric transducers usually uses room temperature as the reference temperature. Therefore, when the piezoelectric transducer works in a non-room temperature environment, its sensitivity will decrease due to the drift of the resonant frequency.

[0004] To solve this problem, the existing technology has adopted some methods, such as setting a temperature compensation circuit or using an adaptive filtering algorithm for compensation, but these methods usually require the introduction of additional circuit elements, which is not conducive to the miniaturization of the transducer and also makes the signal processing process more complicated.

[0005] Therefore, the industry has been seeking a simple and effective method to improve the performance and adaptability of piezoelectric ultrasonic transducers in non-room temperature environments. Summary of the invention

[0006] The present invention proposes a temperature adaptability method for a piezoelectric transducer, which can solve the temperature adaptability problem of a piezoelectric ultrasonic transducer. By optimizing the conductivity characteristics of the transducer, its performance can meet the target temperature requirements in a non-room temperature environment.

[0007] The present invention provides a method for temperature adaptability of a piezoelectric transducer, comprising: Obtain the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization; Calculate the difference f2-f1=Δf between the resonant frequency f1 of the transducer before optimization at room temperature and the resonant frequency f2 at the target temperature; The transducer is optimized according to a preset optimization strategy, so that the difference between the resonant frequency f3 of the optimized transducer at room temperature and the resonant frequency f1 of the transducer before optimization at room temperature is f3-f1=-Δf.

[0008] As an optional implementation, the preset optimization strategy is to keep the thickness of the matching layer and the thickness of the backing layer unchanged, and adjust the thickness of the piezoelectric layer; For a piezoelectric transducer, the transducer has the maximum transmission and reception response when its operating frequency is the resonant frequency of the piezoelectric material, and the resonant frequency and size of the thickness vibration mode of the piezoelectric material have the following relationship: N t =f×t p ; Where N t is the frequency constant of the thickness vibration mode, f is the thickness resonance frequency, t p is the thickness of the piezoelectric layer. Since the conventional piezoelectric transducer is a longitudinal wave transducer, it works using the thickness resonance mode of the piezoelectric material block. The thickness resonance frequency f here is the resonance frequency f1 at room temperature. When the piezoelectric transducer is at the target operating temperature, the thickness resonance frequency shifts from f1 to f2 = f1 + Δf, and the thickness of the piezoelectric layer is reduced from t p1 Adjust to t p2 =t p1 +Δt p , so that f1×t p1 =f2×t p2 , it is calculated that in order to compensate for the frequency drift of the transducer at the target temperature, the thickness of the piezoelectric layer that needs to be adjusted is Δt p =-Δf×t p1 / (f1+Δf); where the conventional piezoelectric transducer is a longitudinal wave transducer, which works by using the thickness resonance mode of the piezoelectric material block, t p1 and t p2 Refers to the thickness dimension before and after optimization. However, if the thickness resonance mode is not used, such as the radial resonance mode, t here refers to the radial dimension, then the corresponding t p1 and t p2 Refers to the radial dimensions before and after optimization.

[0009] As an optional implementation, the preset optimization strategy is to keep the thickness of the piezoelectric layer and the thickness of the backing layer unchanged, adjust the thickness of the matching layer, and test the transducer conductance spectrum with different matching layer thicknesses to experimentally predetermine the matching layer thickness change Δt required to cause the frequency drift -Δf m , to adjust the thickness of the matching layer, thereby achieving temperature adaptation compensation of the piezoelectric transducer.

[0010] As an optional implementation, the conductivity characteristic of the transducer at room temperature is a single-peak conductivity spectrum, and the resonant frequency f1 is equal to the operating frequency f w .

[0011] As an optional implementation, the conductivity characteristic of the transducer at room temperature is a double-peak conductivity spectrum, and the resonance frequencies of the two conductivity peaks are f a and f b, the resonant frequency f1 is equal to the operating frequency f w , resonant frequency f1 or operating frequency f w Satisfy f a <f w <f b .

[0012] As an optional implementation, obtaining the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization includes: Test the conductivity characteristics of the transducer before optimization at room temperature and record the resonant frequency f1 of the transducer before optimization at room temperature; The conductivity characteristics of the transducer before optimization at the target temperature are tested and the resonant frequency f2 of the transducer before optimization at the target temperature is recorded.

[0013] As an optional implementation, the target temperature is an extreme temperature environment other than room temperature.

[0014] As an optional implementation, after optimizing the transducer according to a preset optimization strategy so that the difference between the resonant frequency f3 of the optimized transducer at room temperature and the resonant frequency f1 of the transducer before optimization at room temperature is f3-f1=-Δf, the method further includes: Test the conductivity characteristics of the optimized transducer at room temperature and record the resonant frequency f3 of the optimized transducer at room temperature; test the conductivity characteristics of the optimized transducer at the target temperature and record the resonant frequency of the optimized transducer at the target temperature, at which time the resonant frequency is equal to the resonant frequency f1 of the transducer at room temperature before optimization.

[0015] As an optional implementation, the transducer is an air-coupled piezoelectric ultrasonic transducer.

[0016] The present invention has at least the following beneficial effects: 1. The present invention tests the resonant frequency of the piezoelectric ultrasonic transducer at room temperature and target temperature respectively, and compensates for the resonant frequency drift by adjusting the structural parameters of the piezoelectric transducer itself, without adding an additional temperature compensation circuit or algorithm; 2. The present invention proposes a method for solving the temperature adaptability of a piezoelectric ultrasonic transducer by analyzing the conductance spectrum of the transducer at room temperature and target temperature, thereby providing a new solution for the development of temperature compensation technology for piezoelectric transducers. The problem of frequency drift of piezoelectric ultrasonic transducers at extreme working temperatures other than room temperature can be solved more simply, thereby improving the transceiver performance of piezoelectric transducers in working temperature environments other than room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A schematic flow chart of a method for temperature adaptability of a transducer in an embodiment of the present application is shown.

[0018] Figure 2 A schematic flow chart of yet another method for temperature adaptability of a transducer in an embodiment of the present application is shown.

[0019] Figure 3 The conductivity spectrum curves of the transducer at room temperature and target temperature before optimization in one embodiment of the present application are shown.

[0020] Figure 4 The receiving waveforms of the transducer before optimization at room temperature and target temperature in one embodiment of the present application are shown.

[0021] Figure 5 The conductivity spectrum curves of the optimized transducer at room temperature and target temperature in one embodiment of the present application are shown.

[0022] Figure 6 The receiving waveforms of the optimized transducer at room temperature and target temperature in one embodiment of the present application are shown. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0024] like Figure 1 and Figure 2 As shown, the present invention provides a temperature adaptability method for a piezoelectric transducer, comprising: Step S100: Obtain the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization; wherein the resonant frequency f1 is the operating frequency f of the transducer. w , the resonant frequency f2 of the transducer at the target temperature before optimization deviates from the operating frequency f w , its transmission and reception performance will be reduced; Step S200: Calculate the difference f2-f1=Δf between the resonant frequency f1 of the transducer before optimization at room temperature and the resonant frequency f2 at the target temperature; Step S300: Optimizing the transducer according to a preset optimization strategy, so that the difference between the resonant frequency f3 of the optimized transducer at room temperature and the resonant frequency f1 of the transducer before optimization at room temperature is f3-f1=-Δf, so as to achieve compensation for the resonant frequency drift when working at the target temperature. The resonant frequency f3 at this time is different from the resonant frequency f1 under the traditional design method; Step S400: placing the optimized transducer in a high and low temperature test chamber, and adjusting the temperature of the test chamber to a target temperature.

[0025] Specifically, the optimized transducer is placed in a high and low temperature test chamber, the temperature of the test chamber is adjusted to the target operating temperature, and the resonant frequency f4 of the optimized piezoelectric transducer is tested. At this time, f4 = f w Therefore, when working at the target temperature, the transmitting and receiving performance of the piezoelectric transducer will meet the design requirements.

[0026] Preferably, adjusting the thickness of the backing layer cannot adjust the resonant frequency of the piezoelectric transducer. The backing layer is used to absorb the sound waves emitted backward by the piezoelectric transducer. The backing layer is mainly used to control the bandwidth and noise. The thicker the backing, the weaker the sound waves reflected at the rear end of the backing layer, and the smaller the noise.

[0027] In one embodiment of the present invention, the specific transducer preset optimization strategy is to keep the thickness of the matching layer and the thickness of the backing layer unchanged and adjust the thickness of the piezoelectric layer; or to keep the thickness of the piezoelectric layer and the thickness of the backing layer unchanged and adjust the thickness of the matching layer.

[0028] Specifically, the transducer is optimized according to a preset optimization strategy by changing the thickness of the piezoelectric layer from t p1 Adjust to t p2 =t p1 +Δt p , so that f1×t1=f2×t2, and the piezoelectric layer thickness Δt that needs to be adjusted to compensate for the frequency drift of the transducer at the target temperature is calculated. p =-Δf×t p1 / (f1+Δf).

[0029] Specifically, by testing the transducer conductance spectra with different matching layer thicknesses, the matching layer thickness change Δt required to cause the frequency drift -Δf is experimentally determined in advance. m , to adjust the thickness of the matching layer, thereby achieving temperature adaptation compensation of the piezoelectric transducer.

[0030] In one embodiment of the present invention, the conductivity characteristic of the transducer at room temperature is a single-peak conductivity spectrum, and the resonant frequency f1 is equal to the operating frequency f w .

[0031] In one embodiment of the present invention, the conductivity characteristic of the transducer at room temperature is a double-peak conductivity spectrum, and the resonance frequencies of the two conductivity peaks are f a and f b , the resonant frequency f1 is equal to the operating frequency f w , resonant frequency f1 or operating frequency f w Satisfy f a <f w <f b .

[0032] For the conductivity characteristics of the transducer at room temperature (~25°C) before optimization, its conductivity spectrum can be a single peak, that is, the resonant frequency f1 is equal to the operating frequency f w ; The conductivity spectrum can also be double-peaked, and the resonance frequencies of the two conductivity peaks are f a and f b , the piezoelectric transducer works in the coupled mode of these two resonant modes, and the operating frequency is f w (f a <f w <f b ) is equal to the frequency of the coupled mode.

[0033] like Figure 2 As shown, in one embodiment of the present invention, in step S100, obtaining the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization includes: Step S110: testing the conductivity characteristics of the transducer before optimization at room temperature and recording the resonant frequency f1 of the transducer before optimization at room temperature; Step S120: testing the conductivity characteristics of the transducer before optimization at the target temperature and recording the resonant frequency f2 of the transducer before optimization at the target temperature.

[0034] In one embodiment of the present invention, the room temperature may be 25°C.

[0035] In one embodiment of the present invention, the target temperature is an extreme temperature environment other than room temperature.

[0036] Specifically, the target temperature is the target operating temperature, and the target operating temperature may be 80° C. Those skilled in the art may also set a corresponding temperature value according to an actual working scenario, while still falling within the scope of protection of the present invention.

[0037] In an application scenario of the present invention, the transducer is specifically an air-coupled piezoelectric ultrasonic transducer, which is a special type of piezoelectric ultrasonic transducer that can measure gas flow.

[0038] like Figure 3As shown in the figure, the conductivity spectrum curves of the transducer before optimization at room temperature and target temperature are shown. At room temperature, it has two vibration modes, and the corresponding resonance peak frequencies are f a1 and f b1 At the target temperature, the conductivity spectrum of the transducer still maintains two vibration modes, but the resonant frequencies move forward, which are f a2 and f b2 The working frequency of the transducer is f w Remain unchanged.

[0039] like Figure 4 As shown in the figure, the receiving waveform of the transducer at room temperature and target temperature before optimization, the sensitivity at room temperature (signal peak-to-peak value, V pp ) is much higher than the V pp This is because for the air-coupled piezoelectric ultrasonic transducer, it works by using the coupling mode of these two vibration modes, and the frequency of the coupling mode is equal to the excitation signal frequency f w At this time, the transmitting and receiving performance of the transducer is the best. However, at the target temperature, due to the drift of the resonant frequency, the coupling mode frequency used by the transducer deviates from the excitation signal frequency (Δf). Therefore, the transmitting and receiving performance of the transducer decreases, the sensitivity decreases, and cannot meet the application requirements.

[0040] like Figure 5 As shown in the figure, the conductivity spectrum of the optimized transducer at room temperature and target temperature is shown. By optimizing the air-coupled piezoelectric ultrasonic transducer and changing the thickness of the matching layer, the resonance frequencies of the two conductivity peaks at room temperature are f a3 and f b3 , the difference between the frequency of the coupled mode and the operating frequency is -Δf, which is used to compensate for the frequency drift of the transducer at the target temperature. Therefore, when the optimized transducer is at the target temperature, its operating frequency will be equal to the frequency of the coupled mode.

[0041] like Figure 6 As shown, the figure shows the receiving waveforms of the optimized transducer at room temperature and target temperature. Compared with room temperature, the sensitivity of the transducer at the target temperature is at a higher level and can meet the use requirements.

[0042] Here, in this way, the temperature adaptability of the transducer and the performance at the target temperature can be improved.

[0043] Here, the method for transducer temperature adaptability proposed in the present invention is simple and easy to implement. It can solve the problem of frequency drift of piezoelectric transducers at extreme working temperatures other than room temperature, and can also improve the transceiver performance of the transducer in extreme temperature environments other than room temperature.

[0044] It should also be understood that the terms used in this disclosure are only for the purpose of describing specific embodiments and are not intended to limit the disclosure. As used in this disclosure and claims, the singular forms of "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in this disclosure and claims refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0045] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0046] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for temperature adaptability of a piezoelectric transducer, characterized in that: include: Obtain the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization; Calculate the difference f2-f1=Δf between the resonant frequency f1 of the transducer at room temperature before optimization and the resonant frequency f2 at the target temperature; optimize the transducer according to the preset optimization strategy so that the difference f3 of the resonant frequency f3 of the optimized transducer at room temperature and the resonant frequency f1 of the transducer before optimization at room temperature is f3-f1=-Δf.

2. The method for temperature adaptability of a piezoelectric transducer according to claim 1, characterized in that: The preset optimization strategy is to keep the thickness of the matching layer and the thickness of the backing layer unchanged and adjust the thickness of the piezoelectric layer.

3. The method for temperature adaptability of a piezoelectric transducer according to claim 2, characterized in that: The preset optimization strategy is to keep the thickness of the matching layer and the thickness of the backing layer unchanged and adjust the thickness of the piezoelectric layer, including: By changing the thickness of the piezoelectric layer from t p1 Adjust to t p2 =t p1 +Δt p , so that f1×t p1 =f2×t p2 , the piezoelectric layer thickness Δt that needs to be adjusted to compensate for the frequency drift of the transducer at the target temperature is calculated p =-Δf×t p1 / (f1+Δf), where t p1 and t p2 Refers to the thickness size before and after optimization.

4. The method for temperature adaptability of a piezoelectric transducer according to any one of claims 1 to 3, characterized in that: The optimizing the transducer according to the preset optimization strategy also includes: The thickness of the piezoelectric layer and the thickness of the backing layer are kept constant, and the thickness of the matching layer is adjusted.

5. The method for temperature adaptability of a piezoelectric transducer according to claim 4, characterized in that: The method of maintaining the thickness of the piezoelectric layer and the thickness of the backing layer unchanged and adjusting the thickness of the matching layer comprises: By testing the transducer conductance spectrum with different matching layer thicknesses, the required matching layer thickness change Δt to induce the frequency drift -Δf is experimentally determined in advance. m , to adjust the matching layer thickness.

6. The method for temperature adaptability of a piezoelectric transducer according to claim 1, characterized in that: The conductivity characteristic of the transducer at room temperature is a single-peak conductivity spectrum, and the resonant frequency f1 is equal to the operating frequency f w .

7. The method for temperature adaptability of a piezoelectric transducer according to claim 1, characterized in that: The conductivity characteristic of the transducer at room temperature is a double-peak conductivity spectrum, and the resonant frequency f1 is equal to the operating frequency f w The resonant frequencies of the two conductivity peaks are f a and f b , resonant frequency f1 or operating frequency f w Satisfy f a <f w <f b .

8. The method for temperature adaptability of a piezoelectric transducer according to claim 1, characterized in that: The step of obtaining the resonant frequency f1 of the transducer at room temperature and the resonant frequency f2 at the target temperature before optimization includes: The conductivity characteristics of the transducer before optimization at room temperature are tested and the resonant frequency f1 of the transducer before optimization at room temperature is recorded; the conductivity characteristics of the transducer before optimization at the target temperature are tested and the resonant frequency f2 of the transducer before optimization at the target temperature is recorded.

9. The method for temperature adaptability of a piezoelectric transducer according to claim 1, characterized in that: The transducer is optimized according to a preset optimization strategy so that the difference between the resonant frequency f3 of the optimized transducer at room temperature and the resonant frequency f1 of the transducer before optimization at room temperature is f3-f1=-Δf, including: Test the conductivity characteristics of the optimized transducer at room temperature and record the resonant frequency f3 of the optimized transducer at room temperature; test the conductivity characteristics of the optimized transducer at the target temperature and record the resonant frequency of the optimized transducer at the target temperature, at which time the resonant frequency is equal to the resonant frequency f1 of the transducer at room temperature before optimization.

10. The method for temperature adaptability of a piezoelectric transducer according to claim 1, wherein the transducer can be any piezoelectric ultrasonic transducer.

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