A high-precision ultrasonic transducer, an ultrasonic liquid level meter measurement module and a liquid level measurement system
By using the resonant excitation of a high-precision ultrasonic transducer and a high-precision detection circuit, the problem of difficulty in recognizing small signals at the edge of a cup by traditional ultrasonic transducers is solved, thus achieving high-precision liquid level measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HENAN HANWEI ELECTRONICS
- Filing Date
- 2025-05-29
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional ultrasonic transducers have low sensitivity to small signals such as the rim of a cup, resulting in insufficient measurement accuracy and stability, and making it difficult to effectively identify signals from both the rim of the cup and the surface of the liquid at the same time.
A high-precision ultrasonic transducer is used, including a transducer excitation circuit, a signal amplification circuit, a high-precision detection circuit, and a control circuit. The transmitted energy is increased through resonant excitation, the high-precision detection circuit processes small signals, and the distance is calculated using peak discrimination.
It improves the signal-to-noise ratio and ranging accuracy, ensures accurate identification of signals from the cup rim and liquid surface, and avoids the influence of signal magnitude on measurement results.
Smart Images
Figure CN224499636U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of ultrasonic measurement technology, and in particular to a high-precision ultrasonic transducer, an ultrasonic level gauge module, and a level measurement system. Background Technology
[0002] As the principle of ultrasonic measurement tells us, ultrasonic measurement uses a transducer to drive a converter to send and receive ultrasonic waves, and uses the speed of ultrasonic waves in the air to measure distance. However, in practical applications, traditional transducers have low sensitivity to small signals such as those on the rim of a cup, thus failing to guarantee measurement accuracy and stability, and making it impossible to simultaneously and effectively identify small signals such as those on the rim of a cup and large signals such as those on the surface of the liquid.
[0003] Traditional ultrasonic transducers suffer from low sensitivity to small signals, such as those from the rim of the cup, when measuring signals from the liquid surface. This makes it impossible to simultaneously and effectively identify signals from both the rim and the liquid surface. Consequently, the measurement accuracy and stability are insufficient, making it difficult to meet the requirements of high-precision measurements. Utility Model Content
[0004] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application. Such simplifications or omissions shall not be used to limit the scope of this utility model.
[0005] To address the shortcomings of existing technologies, one objective of this utility model is to provide a high-precision ultrasonic transducer.
[0006] To achieve the above objectives, this utility model adopts the following technical solution: a high-precision ultrasonic transducer, comprising,
[0007] A transducer excitation circuit, comprising an electrically connected resonant inductor and a drive switch, is used to drive the transducer to transmit ultrasonic signals according to the transducer's operating frequency.
[0008] The signal amplification circuit is electrically connected to the transducer excitation circuit through the transducer and is used to amplify the ultrasonic signal according to the operating frequency of the transducer.
[0009] A high-precision detection circuit, electrically connected to a signal amplification circuit, is used to detect the input ultrasonic signal and output the detected signal; and,
[0010] The control circuit includes a microcontroller electrically connected to the high-precision detection circuit, used to control the transducer excitation circuit to send ultrasonic waves and to acquire and process the detected signal output by the high-precision detection circuit.
[0011] In a preferred embodiment of the high-precision ultrasonic transducer of this utility model, the signal amplification circuit comprises components electrically connected to each other.
[0012] Input clamping protection is used to clamp and protect large signals at the input of the amplifier circuit when the ultrasonic wave is transmitted.
[0013] Impedance matching is used to match the impedance of the input signal.
[0014] A high-pass filter is used to filter out low-frequency interference and bias voltage; and,
[0015] A non-inverting amplifier is used to amplify the desired signal with low noise.
[0016] In a preferred embodiment of the high-precision ultrasonic transducer described in this utility model, the high-precision detection circuit includes:
[0017] A high-pass filter circuit is connected to the output of the signal amplification circuit to further filter out low-frequency interference;
[0018] An operational amplifier, wherein its non-inverting input is connected to the high-pass filter circuit, and its inverting input is connected to the output via a detector diode;
[0019] A feedback resistor is connected between the output terminal and the inverting input terminal of the operational amplifier; and,
[0020] An RC circuit, connected to the output of the operational amplifier, is used to smooth the detected signal.
[0021] In a preferred embodiment of the high-precision ultrasonic transducer described in this utility model, the control circuit further includes:
[0022] A reset circuit, connected to the microcontroller, is used to perform a reset operation on the microcontroller; and,
[0023] A power coupling capacitor is connected to the power supply terminal of the microcontroller and is used to filter out power supply noise.
[0024] In a preferred embodiment of the high-precision ultrasonic transducer of this utility model, the transducer excitation circuit is resonantly connected to the transducer, and the resonant inductor and the transducer form a resonant circuit.
[0025] In a preferred embodiment of the high-precision ultrasonic transducer of this utility model, the microcontroller controls the drive switch via a PWM control signal.
[0026] The microcontroller acquires the detected signal output by the high-precision detection circuit through the ADC sampling interface, and performs peak identification and distance calculation on the acquired signal.
[0027] To address the shortcomings of existing technologies, another objective of this utility model is to provide an ultrasonic level gauge measurement module.
[0028] To achieve the above objectives, the present invention adopts the following technical solution: an ultrasonic level gauge measuring module, comprising the aforementioned high-precision ultrasonic transducer and a transducer connected thereto, wherein the transducer is used to transmit ultrasonic waves under the drive of the transducer excitation circuit and to receive ultrasonic echo signals.
[0029] As a preferred embodiment of the ultrasonic level gauge measurement module of this utility model, the transducer is a piezoelectric ceramic transducer with a working frequency range of [X1,X2]kHz.
[0030] To address the shortcomings of existing technologies, another objective of this invention is to provide a liquid level measurement system based on a high-precision ultrasonic transducer.
[0031] To achieve the above objectives, the present invention adopts the following technical solution: a liquid level measurement system based on a high-precision ultrasonic transducer, comprising the ultrasonic liquid level measuring module and a terminal device communicatively connected to the ultrasonic liquid level measuring module;
[0032] The terminal device is used to receive and display the cup rim distance, cup rim height, liquid level height, and cup fullness information sent by the ultrasonic level gauge measurement module.
[0033] In a preferred embodiment of the liquid level measurement system based on a high-precision ultrasonic converter described in this utility model, the communication connection is a serial communication connection, and the terminal device is an industrial computer or a PLC controller.
[0034] The beneficial effects of the liquid level measurement system based on a high-precision ultrasonic transducer of this invention are as follows: This invention can increase the transmission energy by several to tens of times by transmitting ultrasonic waves through resonant excitation; it can improve the signal-to-noise ratio by receiving ultrasonic echo signals through resonant LC frequency selection; it can realize the detection of small signals at the mV level through a high-precision detection circuit; and it can improve the ranging accuracy through peak discrimination, without being affected by the signal size. Attached Figure Description
[0035] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0036] Figure 1This is a schematic diagram of the composition and structure of the high-precision ultrasonic transducer of this utility model.
[0037] Figure 2 This is the excitation circuit diagram of the transducer of this utility model.
[0038] Figure 3 This is a circuit diagram of the signal amplification circuit of this utility model.
[0039] Figure 4 This is the high-precision detection circuit diagram of this utility model.
[0040] Figure 5 This is a schematic diagram showing the comparison before and after the high-precision detection circuit processing of this utility model.
[0041] Figure 6 This is the control circuit diagram of this utility model.
[0042] Figure 7 This is a schematic diagram comparing the resonant excitation method of this utility model with the ordinary excitation method.
[0043] Figure 8 This diagram shows a comparison between the high-precision detection circuit of this invention and commonly used detection circuits.
[0044] Figure 9 This is a diagram illustrating the effect of this invention in recognizing signals from the rim of the cup and the liquid surface. Detailed Implementation
[0045] To make the objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.
[0046] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.
[0047] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.
[0048] This invention provides a high-precision ultrasonic transducer capable of identifying signals from the rim of a cup and the liquid surface, thereby enabling the ultrasonic measurement circuit to effectively measure the rim and liquid surface of the cup. The intensity of the ultrasonic signal does not affect the accuracy of the transducer's measurement results.
[0049] Reference Figure 1 This high-precision ultrasonic transducer consists of four parts: a transducer excitation circuit, a signal amplification circuit, a high-precision detection circuit, and a control circuit. Combined with transducer HY1, it forms the entire ultrasonic level gauge measurement module. The main function of the transducer excitation circuit is to drive transducer HY1 to send ultrasonic signals according to its operating frequency.
[0050] Reference Figure 2 The transducer excitation circuit consists of a resonant inductor L1 and a drive switch Q1. The resonant inductor L1 and the transducer HY1 form a resonant circuit. In this embodiment, the resonant circuit can not only increase the driving capability by more than 11.2dB when the drive switch Q1 drives the transducer HY1, but also improve the signal-to-noise ratio by about 33.9dB when the transducer HY1 receives the ultrasonic echo signal.
[0051] Reference Figure 3 The main function of the signal amplification circuit is to amplify the ultrasonic signal according to the operating frequency of transducer HY1. The signal amplification circuit consists of input clamping protection, impedance matching, a high-pass filter, and a non-inverting amplifier.
[0052] Specifically, input clamping protection (by...) Figure 3 The circuit (composed of R7, D3, and D4) is used to clamp the large signal at the input of the amplifier circuit during ultrasonic wave transmission. The signal Sig_1 is input from the left side of R7 and output from the right side of R7 as Sig_1'. The right side of R7 is connected to D3 and D4, using the diode voltage drop to clamp and protect GND.
[0053] Furthermore, impedance matching (by...) Figure 3 The circuit (composed of C1, Q2, R6, R12, and R13) is used for impedance matching of the input signal. Transistor Q2 and the resistors form a typical follower circuit. The signal Sig_1' is isolated by C1, outputting Sig_1'', which then enters the base input of Q2, and finally outputs Sig_1''' from the emitter. The signal amplitude remains unchanged at each point of impedance matching.
[0054] Furthermore, the high-pass filter (made by...) Figure 3 The filter (composed of C4, R14, C3, and R11) is used to filter out low-frequency interference and bias voltage. Signal Sig_1''' or Sig_2' is input through the left side of C4 or C3 and outputs Sig_1'''' or Sig_2' from the right side of C4 or C3. The upper end of R14 or R11 is connected to the right side of C4 or C3, and the lower end of R14 or R11 is connected to GND. This forms a typical RC high-pass filter used to filter out low-frequency noise.
[0055] Among them, the in-phase amplifier (made by Figure 3The operational amplifier circuit (composed of U2A, R2, R5, U1B, R1, and R2) amplifies the desired signal with low noise. Signal Sig_1' or Sig_2' is input from the non-inverting input of operational amplifiers U2A and U1B, and outputs Sig_2 or Sig_3. The inverting input of operational amplifiers U2A and U1B is connected to the left side of R2 and R1 and the upper end of R5 and R3. The lower end of R5 and R3 is connected to GND, and the right side of R2 and R1 is connected to the output of the operational amplifier. The amplification factor of the non-inverting amplifier circuit composed of operational amplifier U2A is G1 = 1 + (R2 / R5), and the amplification factor of the non-inverting amplifier circuit composed of operational amplifier U1B is G2 = 1 + (R1 / R3). The total amplification factor of the amplifier circuit is G = G1 * G2.
[0056] Reference Figure 4 and Figure 5 The main function of the high-precision detection circuit is to perform detection processing on the ultrasonic signal Sig_3 at the input end, and then output the detected signal Sig_4.
[0057] Specifically, the high-precision detection circuit consists of a high-pass filter circuit (composed of...). Figure 4 Composed of C2 and R10), operational amplifier U1A, detector diode (composed of C2 and R10), and detector diode (composed of C2 and R10). Figure 4 Composed of D1 and D2), feedback resistor R4, RC circuit (composed of...) Figure 4 Composed of R9 and C5 (see) Figure 4 ).
[0058] The signal Sig_3 is input from the left end of C2, and outputs Sig_3' from the right end of C2. The right end of C2 is connected to the non-inverting input of operational amplifier U1A. The inverting input of operational amplifier U1A is connected to the upper end of D1 and the upper end of R4. The output of U1A is connected to the lower end of D1 and the left end of D2. The right end of D2 is connected to the lower end of R4, the upper end of C5, and the upper end of R9, outputting the signal Sig_4. The lower ends of C5 and R9 are connected to GND.
[0059] Reference Figure 6 and Figure 7 The main function of the control circuit is to send ultrasonic waves from the control excitation circuit and the ultrasonic signals obtained by the conversion and detection circuit, and to perform digital conversion.
[0060] Specifically, the control circuit mainly consists of a microcontroller U3 and a reset circuit (by...). Figure 6 (composed of R15 and C6) and power supply coupling capacitor (composed of Figure 6It consists of C7 and C8. The ultrasonic wave is transmitted by the PWM control signal output from the PC3 interface of the microcontroller (U3). The ultrasonic echo signal is received by the ADC sampling of the PC5 interface of the microcontroller U3 to acquire the signal Sig_4. The peak value identification and calculation of the echo signal are completed by the microcontroller U3. Serial communication is realized by the PB4 and PB5 interfaces of the microcontroller U3 to realize data exchange.
[0061] When the converter transmits ultrasonic waves, it controls the drive switch of the transducer excitation circuit through the PWM output of the control circuit, thereby stimulating transducer HY1 to transmit ultrasonic waves. The resonant excitation method composed of resonant inductor L1 and transducer HY1 effectively enhances the transmission intensity, increasing the transmission power by more than 11.2 dB. When the converter receives the ultrasonic echo, it uses the LC resonance of the transducer excitation circuit for frequency selection, thereby improving the signal-to-noise ratio of the echo signal by approximately 33.9 dB. In an optional embodiment, the LC resonance of the transducer excitation circuit can be replaced by a transformer-coupled LC resonance.
[0062] Furthermore, the input stage of the signal amplification circuit includes a high-pass filter, which effectively filters DC bias and low-frequency interference. The amplification uses a G-fold in-phase amplification, ensuring minimal signal phase delay. The amplified signal then enters a high-precision detection circuit for detection, facilitating sampling and calculation by the ADC in the control circuit. A typical detection circuit consists of a diode, a resistor, and a capacitor.
[0063] Reference Figure 8 A high-precision detector circuit consists of an operational amplifier, two diodes, a resistor, and a capacitor. In conventional detector circuits, the response time and forward voltage drop of the detector diodes cause significant signal distortion at voltages of tens of mV, and even smaller signals are lost. The high-precision detector circuit adds an operational amplifier to the conventional circuit to improve the response speed and compensate for the forward voltage drop of the detector diodes, thus effectively handling signals below 1 mV.
[0064] The signal detected by the high-precision detection circuit is connected to the ADC sampling circuit of the control circuit. The sampled data is then analyzed using peak detection. By combining the speed of sound in air and a fixed sampling rate, accurate information such as the distance to the rim, the height of the rim, the liquid level, and the fullness of the cup can be calculated. This information is then exchanged with other terminals via serial communication.
[0065] The comparator method commonly used in ultrasonic ranging suffers from poor detection accuracy and exhibits varying delays depending on signal strength. Peak detection, on the other hand, avoids this issue in principle, as signal strength does not affect the peak position. (Refer to...) Figure 9The description refers to the actual signals measured at the rim of the cup and the liquid level. In practice, the signal at the rim is typically tens to hundreds of times smaller than the signal at the liquid level, and it varies depending on the placement. Common comparator discrimination methods introduce a positive bias due to the rim distance, and a negative bias due to the full coverage of the liquid level and the rim. Our peak discrimination method is completely unaffected by the signal magnitude.
[0066] This utility model also provides an ultrasonic level gauge measurement module and a level measurement system based on a high-precision ultrasonic converter.
[0067] Ultrasonic level gauge measurement module: includes a high-precision ultrasonic transducer and a connected transducer. The transducer is typically a piezoelectric ceramic transducer, operating within a specific kHz range to ensure effective transmission and reception of ultrasonic waves.
[0068] Liquid level measurement system: This includes an ultrasonic level gauge measurement module and a terminal device that communicates with it. The terminal device receives and displays information such as the distance to the cup rim, the height of the cup rim, the liquid level, and the cup fullness sent by the ultrasonic level gauge measurement module. The communication connection is typically a serial communication connection, and the terminal device can be an industrial computer or a PLC controller, which facilitates data transmission and processing.
[0069] In practical applications, when it is necessary to measure the liquid level and rim height of a cup filled with liquid, the converter starts working. The microcontroller U3 in the control circuit sends a PWM control signal to drive the drive switch in the transducer excitation circuit. The resonant circuit composed of the resonant inductor and the transducer then comes into play, increasing the transmitted power by more than 11.2dB. This means that the transmitted energy of the ultrasonic signal is significantly improved, allowing it to reach the target object (rim of the cup or liquid surface) and return more effectively.
[0070] When an ultrasonic signal encounters the rim of a cup or the surface of a liquid and returns, the transducer receives the echo signal. These signals are often very weak, especially the rim signal, which can be tens to hundreds of times weaker than the surface signal. At this point, the high-precision detection circuit begins to operate. Its high-pass filter circuit first filters out low-frequency interference, ensuring signal purity. The operational amplifier increases the detection speed and compensates for the forward voltage drop of the detection diode, enabling even a small signal of only 1mV to be accurately detected. In this way, the rim signal, which would otherwise be easily ignored, can be clearly identified.
[0071] The microcontroller U3 in the control circuit acquires the detected signal through the ADC sampling interface. Unlike traditional comparator discrimination methods, this invention uses a peak discrimination method. This method does not depend on the signal magnitude but calculates the distance based on the peak position of the signal. This is because, regardless of signal strength, its peak position accurately reflects the ultrasonic wave return time, thus ensuring the accuracy of the distance measurement. This method effectively avoids measurement deviations caused by differences in signal magnitude, ensuring accurate and reliable measurements of the cup rim distance and liquid level height.
[0072] The above embodiments demonstrate the advantages and effects of this invention in practical applications. By employing key technologies such as resonant excitation to increase transmission energy, high-precision detection circuit to process small signals, and peak discrimination to improve ranging accuracy, this invention effectively solves the problems existing in traditional ultrasonic transducers when measuring signals at the rim of a cup and the liquid surface, providing a reliable solution for high-precision liquid level measurement.
[0073] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.
[0074] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A high-precision ultrasonic transducer, characterized in that: include, The transducer excitation circuit includes an electrically connected resonant inductor (L1) and a drive switch (Q1) for driving the transducer (HY1) to send ultrasonic signals according to the operating frequency of the transducer (HY1); The signal amplification circuit is electrically connected to the transducer excitation circuit through the transducer (HY1) and is used to amplify the ultrasonic signal according to the operating frequency of the transducer (HY1). A high-precision detection circuit, electrically connected to a signal amplification circuit, is used to detect the input ultrasonic signal and output the detected signal; and, The control circuit includes a microcontroller (U3) electrically connected to the high-precision detection circuit, used to control the transducer excitation circuit to send ultrasonic waves and to acquire and process the detected signal output by the high-precision detection circuit.
2. The high-precision ultrasonic transducer as described in claim 1, characterized in that: The signal amplification circuit includes components that are electrically connected to each other. Input clamping protection is used to clamp and protect large signals at the input of the amplifier circuit when the ultrasonic wave is transmitted. Impedance matching is used to match the impedance of the input signal. A high-pass filter is used to filter out low-frequency interference and bias voltage; and, A non-inverting amplifier is used to amplify the desired signal with low noise.
3. The high-precision ultrasonic transducer as described in claim 1, characterized in that: The high-precision detection circuit includes, A high-pass filter circuit is connected to the output of the signal amplification circuit to further filter out low-frequency interference; The operational amplifier (U1A) has its non-inverting input connected to the high-pass filter circuit, and its inverting input connected to the output via a detector diode. A feedback resistor (R4) is connected between the output terminal and the inverting input terminal of the operational amplifier (U1A); and, An RC circuit, connected to the output of the operational amplifier (U1A), is used to smooth the detected signal.
4. The high-precision ultrasonic transducer as described in any one of claims 1 to 3, characterized in that: The control circuit also includes, A reset circuit, connected to the microcontroller (U3), is used to perform a reset operation on the microcontroller (U3); and, A power coupling capacitor is connected to the power supply terminal of the microcontroller (U3) and is used to filter out power supply noise.
5. The high-precision ultrasonic transducer as described in claim 4, characterized in that: The transducer excitation circuit is resonantly connected to the transducer (HY1), and the resonant inductor (L1) and the transducer (HY1) form a resonant circuit.
6. The high-precision ultrasonic transducer as described in claim 5, characterized in that: The microcontroller (U3) controls the drive switch (Q1) through a PWM control signal. The microcontroller (U3) acquires the detected signal output by the high-precision detection circuit through the ADC sampling interface, and performs peak identification and distance calculation on the acquired signal.
7. An ultrasonic level gauge measuring module, comprising a high-precision ultrasonic transducer as described in any one of claims 1 to 6 and a transducer (HY1) connected thereto, characterized in that: The transducer (HY1) is used to transmit ultrasonic waves under the drive of the transducer excitation circuit and to receive ultrasonic echo signals.
8. The ultrasonic level gauge measuring module as described in claim 7, characterized in that: The transducer (HY1) is a piezoelectric ceramic transducer with an operating frequency range of [X1,X2]kHz.
9. A liquid level measurement system based on a high-precision ultrasonic transducer, characterized in that: Includes the ultrasonic level gauge measurement module as described in claim 7 or 8, and a terminal device that is communicatively connected to the ultrasonic level gauge measurement module; The terminal device is used to receive and display the cup rim distance, cup rim height, liquid level height, and cup fullness information sent by the ultrasonic level gauge measurement module.
10. The liquid level measurement system based on a high-precision ultrasonic transducer as described in claim 9, characterized in that: The communication connection is a serial communication connection, and the terminal device is an industrial control computer or a PLC controller.