Broadband air ultrasonic sensor

Abstract

The invention relates to the technical field of ultrasonic sensors, and provides a broadband air ultrasonic sensor, which comprises a shell, at least two piezoelectric ceramic pieces and a circuit board, and is characterized in that the shell is provided with a plurality of acquisition holes; the at least two piezoelectric ceramic pieces are fixedly arranged in the shell and correspond to the collection holes in the shell respectively, the piezoelectric ceramic pieces collect ultrasonic signals through the collection holes, and the frequency bands of the at least two piezoelectric ceramic pieces are different. According to the broadband air ultrasonic sensor, a plurality of piezoelectric ceramic pieces with different frequency bands are integrated, the frequency compensation module is arranged, and the frequency bands among the piezoelectric ceramic pieces with different frequency bands are compensated, so that collection and output of broadband sound waves of dozens of kilohertz are achieved, and then the broadband air ultrasonic sensor can be used in some application scenes. And a single sensor is used for carrying out wider-frequency-band ultrasonic wave acquisition operation, so that the spatial layout optimization and design of equipment are greatly facilitated, and the equipment cost for broadband detection is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic sensors, and in particular to a broadband air ultrasonic sensor. Background Art

[0002] An air ultrasonic sensor is a device that uses the propagation characteristics of ultrasound in the air to receive sound waves. It can be used to detect objects or measure distances. Ultrasonic spectrum detection uses the propagation and reflection characteristics of ultrasound waves of different frequencies in different media. By analyzing the received signal spectrum, the sensor can identify the material, shape, and surface characteristics of the object. This enables air ultrasonic sensors to not only detect the presence or distance of an object, but also perform more complex material analysis and structural diagnosis.

[0003] Existing air ultrasonic sensors all have fixed frequency bands. Taking an ultrasonic probe with a center frequency of 40kHz as an example, its actual frequency band is 39kHz to 41kHz. In some applications, it is necessary to detect ultrasonic signals of a certain width, and the required coverage bandwidth is usually tens of kilohertz. For example, in partial discharge detection, the discharge type is determined by ultrasonic spectrum analysis of the discharge. In gas leak detection, the size of the leak can be determined by ultrasonic spectrum analysis. For such application scenarios that require ultrasonic spectrum detection, multiple sensors are required. Each sensor is designed for a different frequency range and covers a wide frequency range through an array. Alternatively, multiple ultrasonic sensors with the same performance are used to increase the sensitivity within a certain wide frequency range. This method is particularly effective in complex environments, but this setting requires the use of more sensors, which is not conducive to the spatial layout of the equipment and will increase the equipment cost. Summary of the invention

[0004] In view of this, the present invention proposes a broadband air ultrasonic sensor, which integrates multiple piezoelectric ceramic sheets with different frequency bands and sets a frequency compensation module to compensate the frequency bands between piezoelectric ceramic sheets with different frequency bands, so as to realize broadband sound wave collection and output of tens of kilohertz, and then complete the operation of wide-band ultrasonic collection by a single sensor in certain application scenarios, which greatly facilitates the spatial layout optimization and design of the equipment, and effectively reduces the equipment cost for broadband detection.

[0005] The technical solution of the present invention is implemented as follows: The present invention provides a broadband air ultrasonic sensor, comprising a housing, at least two piezoelectric ceramic sheets, and a circuit board, wherein:

[0006] A number of collection holes are provided on the shell;

[0007] At least two piezoelectric ceramic sheets are fixedly arranged in the housing and correspond to the collection holes on the housing respectively. The piezoelectric ceramic sheets collect ultrasonic signals through the collection holes, and the frequency bands of at least two piezoelectric ceramic sheets are different.

[0008] A circuit board is arranged on the shell, and the circuit board includes a frequency compensation module and an addition output module. The frequency compensation module and the addition output module both have a signal input end and a signal output end. The piezoelectric ceramic piece is electrically connected to the signal input end of the frequency compensation module, and the signal output end of the frequency compensation module is electrically connected to the signal input end of the addition output module. The frequency compensation module is used to perform bandwidth compensation on piezoelectric ceramic pieces of different frequency bands so that each discontinuous frequency band is combined to form a continuous frequency band. The addition output module is used to perform addition output on the signal output by the frequency compensation module.

[0009] On the basis of the above technical solution, preferably, it further comprises a flexible substrate and a sound absorbing sheet, wherein:

[0010] The flexible substrate is compositely arranged at the bottom of each piezoelectric ceramic sheet to reduce mutual interference between piezoelectric ceramic sheets with different resonance frequencies;

[0011] The sound absorbing sheet is compositely arranged on the bottom of the flexible substrate, and the sound absorbing sheet is used for absorbing the sound energy in the process of ultrasonic wave conduction.

[0012] On the basis of the above technical solution, preferably, the circuit board also includes a programmable control module, the programmable control module includes a control output end, the frequency compensation module includes a control input end, and the control output end of the programmable control module is electrically connected to the control input end of the frequency compensation module to control the compensation frequency band of the frequency compensation module.

[0013] On the basis of the above technical solution, preferably, the circuit board also includes an impedance matching module, the impedance matching module has a signal input end and a signal output end, and the signal input end is electrically connected to the piezoelectric ceramic piece, the signal output end is electrically connected to the signal input end of the frequency compensation module, the frequency compensation module is electrically connected to the piezoelectric ceramic piece through the impedance matching module, and the impedance matching module is used to perform impedance matching on the signal output by the piezoelectric ceramic piece.

[0014] On the basis of the above technical solution, preferably, the circuit board also includes an amplifying compensation module, the amplifying compensation module has a signal input end and a signal output end, the signal input end of the amplifying compensation module is electrically connected to the signal output end of the frequency compensation module, the signal output end of the amplifying compensation module is electrically connected to the signal input end of the addition output module, and the addition output module is electrically connected to the frequency compensation module through the amplifying compensation module.

[0015] On the basis of the above technical solution, preferably, the frequency bands of the piezoelectric ceramic sheets are different, and the frequency band difference between two piezoelectric ceramic sheets with similar frequency bands is within a range of 5-15 kHz.

[0016] More preferably, it also includes a sound collector and a ceramic substrate, wherein:

[0017] The number of the sound collectors is the same as the number of the piezoelectric ceramic sheets, and they are correspondingly arranged on each piezoelectric ceramic sheet. The sound collectors correspond to the collection holes one by one to focus the sound waves.

[0018] The number of the ceramic substrates is the same as the number of the piezoelectric ceramic sheets. The ceramic substrates are arranged on the piezoelectric ceramic sheets in a one-to-one correspondence and are located between the piezoelectric ceramic sheets and the flexible substrate.

[0019] Further preferably, the impedance matching module includes an operational amplifier U32, a capacitor C172, a capacitor C175, a capacitor C173, a resistor R147, a resistor R148 and a resistor R149, wherein:

[0020] Pin 4 of the operational amplifier U32 is electrically connected to the piezoelectric ceramic sheet, pin 5 and pin 8 are connected to positive and negative DC power supplies respectively, and pin 1 and pin 6 are grounded;

[0021] One end of capacitor C172 is grounded, and the other end is electrically connected to pin 4 of operational amplifier U32;

[0022] One end of capacitor C175 is grounded, and the other end is electrically connected to pin 4 of operational amplifier U32;

[0023] One end of the capacitor C173 is electrically connected to the pin 7 of the operational amplifier U32, and the other end is electrically connected to the signal input end of the frequency compensation module (31);

[0024] The two ends of the resistor R147 are electrically connected to the two ends of the capacitor C175 respectively;

[0025] The two ends of the resistor R148 are electrically connected to the pin 2 and the pin 3 of the operational amplifier U32 respectively;

[0026] One end of the resistor R149 is grounded, and the other end is electrically connected to one end of the capacitor C173 connected to the frequency compensation module.

[0027] Further preferably, the amplification compensation module includes an operational amplifier U33, a resistor R151, a potentiometer W1, a capacitor C177 and a resistor R152, wherein:

[0028] Pin 4 of the operational amplifier U33 is electrically connected to the signal output terminal of the frequency compensation module, pin 5 and pin 8 are connected to the positive and negative DC power supplies respectively, and pin 1 and pin 6 are grounded;

[0029] The two ends of the resistor R151 are electrically connected to the pin 4 and the pin 1 of the operational amplifier U33 respectively;

[0030] Pin 1 of the potentiometer W1 is electrically connected to pin 2 of the operational amplifier U33, and both pin 2 and pin 3 of the potentiometer W1 are electrically connected to pin 3 of the operational amplifier U33;

[0031] The two ends of capacitor C177 are electrically connected to pin 7 of operational amplifier U33 and the signal input terminal of the addition output module respectively;

[0032] One end of the resistor R152 is grounded, and the other end is electrically connected to one end of the capacitor C177 connected to the addition output module.

[0033] On the basis of the above technical solution, preferably, the addition output module includes an operational amplifier U39, and pin 3 of the operational amplifier U39 is electrically connected to each piezoelectric ceramic sheet to receive the collected data of all the piezoelectric ceramic sheets.

[0034] The broadband air ultrasonic sensor of the present invention has the following beneficial effects compared with the prior art:

[0035] (1) By integrating multiple piezoelectric ceramics with different frequency bands and setting up a frequency compensation module, the frequency bands between piezoelectric ceramics with different frequency bands are compensated to achieve broadband sound wave collection and output of tens of kilohertz, thereby completing the wide-band ultrasonic wave collection operation by a single sensor in certain application scenarios, which greatly facilitates the spatial layout optimization and design of the equipment and effectively reduces the equipment cost for broadband detection;

[0036] (2) The flexible substrate can help reduce the environmental vibration and noise interference to the piezoelectric chip during operation through its vibration isolation properties, especially the mutual interference between piezoelectric ceramic pieces with different frequencies, thereby enabling the piezoelectric ceramic piece integrated on the flexible substrate to operate in a quieter signal environment, thereby improving the signal-to-noise ratio and detection accuracy of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a schematic diagram of the structure of the broadband air ultrasonic sensor of the present invention;

[0039] Figure 2 It is a schematic diagram of a circuit module of a broadband air ultrasonic sensor of the present invention;

[0040] Figure 3 This is an example diagram of the combined frequency bands of five piezoelectric ceramic sheets with different frequency bands of the broadband air ultrasonic sensor of the present invention;

[0041] Figure 4 This is an example diagram of the compensation frequency band of the broadband air ultrasonic sensor of the present invention;

[0042] Figure 5 This is an example diagram of the complete frequency band of the broadband air ultrasonic sensor of the present invention;

[0043] Figure 6 This is an example diagram of a circuit board module of a broadband air ultrasonic sensor of the present invention;

[0044] Figure 7 The impedance matching module circuit diagram of the broadband air ultrasonic sensor of the present invention;

[0045] Figure 8 A circuit diagram of a frequency compensation module of a broadband air ultrasonic sensor of the present invention;

[0046] Fig. 9 The circuit diagram of the amplification compensation module of the broadband air ultrasonic sensor of the present invention;

[0047] Fig.10 It is a circuit diagram of the addition output module of the broadband air ultrasonic sensor of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] like Figure 1-2 As shown, the broadband air ultrasonic sensor of the present invention comprises a housing 1 , at least two piezoelectric ceramic sheets 2 , and a circuit board 3 .

[0050] Several collection holes are provided on the shell 1. The shell 1 is made of metal, preferably aluminum alloy. It is cylindrical in shape and hollow inside. A plurality of collection holes are provided on one circular surface. The number of the collection holes is consistent with the number of the piezoelectric ceramic sheets 2, which are used to conduct sound waves into the shell 1. An interface is also required to be provided on the outside of the shell 1 to realize the transmission of collected data.

[0051] At least two piezoelectric ceramic sheets 2 are fixedly disposed in the housing 1 and correspond to the collection holes on the housing 1 respectively. The piezoelectric ceramic sheets 2 collect ultrasonic signals through the collection holes, and the frequency bands of at least two piezoelectric ceramic sheets 2 are different.

[0052] The piezoelectric ceramic piece 2 is the piezoelectric chip in the sensor. For the convenience of explanation, in this embodiment, five piezoelectric ceramic pieces 2 with different frequency bands are used as examples. The application of a single piezoelectric ceramic piece 2 in an ultrasonic sensor is usually limited by its fixed frequency band characteristics. This is mainly because the sensitivity of the piezoelectric ceramic piece 2 will change significantly with the change of the sound wave frequency. Sensitivity is usually measured in decibels dB. At a certain frequency, if the minimum decibel value required for the ultrasonic signal that the piezoelectric ceramic piece 2 can detect is low, it means that the piezoelectric ceramic piece 2 has a high sensitivity to the ultrasonic wave of that frequency.

[0053] However, different piezoelectric ceramic sheets 2 will show different performance characteristics during the manufacturing process due to differences in material formulation, structural design and manufacturing process. These differences not only affect the electrical properties and mechanical strength of the piezoelectric ceramic sheet 2, but also directly determine its ability to respond to ultrasonic signals of different frequencies. Therefore, a single piezoelectric ceramic sheet 2 can usually only show high sensitivity within a specific frequency band, while in other frequency ranges, the sensitivity may drop significantly. This frequency band limitation makes it difficult for a single piezoelectric ceramic sheet 2 to adapt to a wide frequency range in ultrasonic acquisition applications, and can only be optimized for a specific frequency or frequency band.

[0054] It should be noted that in this embodiment, the frequency bands of the piezoelectric ceramic sheets 2 are different, and the frequency band difference between two piezoelectric ceramic sheets 2 with similar frequency bands is within 5-15kHz to avoid low sensitivity, difficulty in frequency compensation, or reduced accuracy of the compensated signal.

[0055] like Figure 3 As shown, in this embodiment, in order to collect ultrasonic signals within the frequency band range of 25kHz-75kHz, five piezoelectric chips with center frequencies of 30kHz, 40kHz, 50kHz, 60kHz and 70kHz are selected, where the center frequency refers to the frequency with the highest sensitivity. Of course, for the piezoelectric chip with a center frequency of 40kHz, the actual available frequency band may be 39kHz-41kHz. In this embodiment, five piezoelectric chips are set to cover a frequency band with a bandwidth of 50kHz, so that ultrasonic signal collection operations with high sensitivity can be performed within the frequency band range of 25kHz-75kHz.

[0056] like Figure 6As shown, the circuit board 3 is arranged on the shell 1, and the circuit board 3 includes a frequency compensation module 31 and an addition output module 32. The frequency compensation module 31 and the addition output module 32 both have a signal input end and a signal output end. The piezoelectric ceramic piece 2 is electrically connected to the signal input end of the frequency compensation module 31, and the signal output end of the frequency compensation module 31 is electrically connected to the signal input end of the addition output module 32. The frequency compensation module 31 is used to perform bandwidth compensation on the piezoelectric ceramic pieces 2 of different frequency bands so that each discontinuous frequency band is combined to form a continuous frequency band. The addition output module 32 is used to perform addition output on the signal output by the frequency compensation module 31.

[0057] Specifically, the circuit board 3 is integrally arranged inside the housing 1, and together with the piezoelectric ceramic sheet 2 forms an integrated broadband air ultrasonic sensor. Figure 3 As shown in the figure, after the combination of five piezoelectric chips with different frequency bands, there is a large sensitivity fluctuation between the frequency bands. Although high-decibel ultrasound can still be collected, the sensitivity at the junction of the frequency bands is low, and the fluctuation of sensitivity will affect the accuracy of ultrasound collection. Figure 4-5 As shown, in order to avoid this problem, a frequency compensation module 31 is provided, which can perform frequency compensation on the piezoelectric ceramic piece 2 during the process of collecting ultrasonic waves, so as to compensate for the sensitivity at the junction of the frequency bands of the two piezoelectric ceramic pieces 2, so that the sensitivity curve of the detectable frequency band becomes a smooth line. The addition output module 32 is used to perform addition output on the signals collected by the piezoelectric ceramic pieces 2 to form a complete signal of a specific frequency, so as to realize the detection of ultrasonic signals with a bandwidth of 50kHz in a single sensor by setting five piezoelectric ceramic pieces 2.

[0058] As a preferred embodiment, it also includes a flexible substrate 4 and a sound absorbing sheet 5. The flexible substrate 4 is compositely arranged at the bottom of each piezoelectric ceramic sheet 2 to reduce the mutual interference between the piezoelectric ceramic sheets 2 with different resonant frequencies. The sound absorbing sheet 5 is compositely arranged at the bottom of the flexible substrate 4, and the sound absorbing sheet 5 is used to absorb the sound energy during the ultrasonic transmission process.

[0059] The flexible substrate 4 can be selected as a silicone electrode. The flexible substrate 4 is bonded and fixed to the bottom of the piezoelectric ceramic sheet 2. The top of the piezoelectric ceramic sheet 2 is the sound wave collection side. This setting can avoid interference and disturbance between the piezoelectric ceramic sheets 2 when collecting ultrasonic waves. In addition, in order to further reduce the interference between each other, the piezoelectric ceramic sheets 2 are distributed in the shell 1 with a maximum adjustable spacing. In this embodiment, the intermediate frequency band piezoelectric ceramic sheet 2 can be set in the middle of the circular surface of the shell 1, such as a piezoelectric ceramic sheet with a center frequency of 40kHz, and other piezoelectric ceramic sheets 2 are distributed in a ring outside it, thereby further reducing the interference between the piezoelectric ceramic sheets 2.

[0060] The sound absorbing sheet 5 is arranged on the ultrasonic sensor to reduce unnecessary reflections and echoes, thereby improving the performance of the sensor. The sound absorbing sheet 5 is connected to the flexible substrate 4 through an adhesive. Similarly, the flexible substrate 4 is also fixed to the piezoelectric ceramic sheet 2 through an adhesive.

[0061] like Figure 6 As shown, in this embodiment, the circuit board 3 also includes a program control module 33, the program control module 33 includes a control output end, the frequency compensation module 31 includes a control input end, and the control output end of the program control module 33 is electrically connected to the control input end of the frequency compensation module 31 to control the compensation frequency band of the frequency compensation module 31.

[0062] The program control module 33 includes a processor of model STM32F407VET6, which enables the frequency compensation module 31 to perform frequency band compensation by outputting electrical signals.

[0063] like Figure 8 As shown, the frequency compensation module 31 includes a latch U1 and a programmable filter U2. The model of the latch U1 is 54HC373, and the model of the programmable filter U2 is MAX262. The latch U1 is electrically connected to the programmable filter U2. The latch U1 is used to configure the working mode of the programmable filter U2, and is used as a configuration register to save the control signal and setting value of the filter. The programmable filter U2 is equipped with filter design software and has a microprocessor interface. It can control 64 different center frequencies f0, 128 different quality factors Q and 4 working modes, and the center frequency f0 and the quality factor Q can be independently programmed. The range of the center frequency f0 is 1Hz to 140kHz, and the maximum input clock is 4MHz.

[0064] On the programmable filter U2, the program design idea is: first configure the microcontroller IO port to match the filter data port, set the A and B channel working modes, calculate the cutoff frequency fc according to the center frequency f0, calculate the corresponding N value of Q0~Q6 according to the required Q, calculate the corresponding N value of F0~F5 according to the center frequency FCLK / f0, set the A and B channel filter modes low pass, high pass, band pass, band stop, full pass, and match them through the corresponding clock method.

[0065] In this embodiment, since the programmable filter U2 can be set to two working modes, and each working mode can correspond to a compensation waveform, for the center frequency compensation of the five piezoelectric ceramic pieces 2, five waveforms can be used, that is, three programmable filters U2 for compensation. Accordingly, the number of frequency compensation modules 31 is set to three.

[0066] like Figure 6As shown, in this embodiment, the circuit board 3 also includes an impedance matching module 34, the impedance matching module 34 has a signal input end and a signal output end, and the signal input end is electrically connected to the piezoelectric ceramic piece 2, and the signal output end is electrically connected to the signal input end of the frequency compensation module 31, and the frequency compensation module 31 is electrically connected to the piezoelectric ceramic piece 2 through the impedance matching module 34, and the impedance matching module 34 is used to perform impedance matching on the signal output by the piezoelectric ceramic piece 2.

[0067] The signals collected by each piezoelectric ceramic piece 2 need to be impedance matched, that is, the number of impedance matching modules 34 needs to be set to five to process the signals of each piezoelectric ceramic piece 2, such as Figure 7 As shown, taking a certain impedance matching module 34 as an example, the impedance matching module 34 includes an operational amplifier U32, a capacitor C172, a capacitor C175, a capacitor C173, a resistor R147, a resistor R148 and a resistor R149, a pin 4 of the operational amplifier U32 is electrically connected to the piezoelectric ceramic sheet 2, a pin 5 and a pin 8 are respectively connected to a positive and negative DC power supply, a pin 1 and a pin 6 are grounded, one end of the capacitor C172 is grounded, and the other end is electrically connected to pin 4 of the operational amplifier U32, one end of the capacitor C175 is grounded, and the other end is connected to the operational amplifier U3 2 is electrically connected to pin 4 of the operational amplifier U32, one end of the capacitor C173 is electrically connected to pin 7 of the operational amplifier U32, and the other end is electrically connected to the signal input end of the frequency compensation module 31, two ends of the resistor R147 are electrically connected to two ends of the capacitor C175, two ends of the resistor R148 are electrically connected to pin 2 and pin 3 of the operational amplifier U32, one end of the resistor R149 is grounded, and the other end is electrically connected to one end of the frequency compensation module 31 connected to the capacitor C173, and the model of the operational amplifier U32 can be selected as AD8421.

[0068] When processing a signal, a certain amplitude attenuation will be introduced, especially in the passband and transition band regions of the filter. By adding an amplification compensation circuit after the filter, the original amplitude of the signal can be restored or increased to the desired level, thereby ensuring that subsequent circuits or devices can receive signals of sufficient strength. Therefore, in this embodiment, the circuit board 3 also includes an amplification compensation module 35, and the amplification compensation module 35 has a signal input end and a signal output end. The signal input end of the amplification compensation module 35 is electrically connected to the signal output end of the frequency compensation module 31, and the signal output end of the amplification compensation module 35 is electrically connected to the signal input end of the addition output module 32. The addition output module 32 is electrically connected to the frequency compensation module 31 through the amplification compensation module 35.

[0069] The purpose of setting up an amplification compensation circuit behind the programmable filter is to restore and enhance the amplitude of the signal, ensuring that the signal still has sufficient strength and quality after filtering, so as to meet the requirements of subsequent processing circuits and optimize the performance of the entire system.

[0070] Since each frequency compensated signal needs to be amplified and compensated, five amplification and compensation modules 35 are provided, such as Fig. 9 As shown, taking one of them as an example, the amplification compensation module 35 includes an operational amplifier U33, a resistor R151, a potentiometer W1, a capacitor C177 and a resistor R152, pin 4 of the operational amplifier U33 is electrically connected to the signal output end of the frequency compensation module 31, pin 5 and pin 8 are respectively connected to the positive and negative DC power supplies, pin 1 and pin 6 are grounded, the two ends of the resistor R151 are respectively electrically connected to pin 4 and pin 1 of the operational amplifier U33, pin 1 of the potentiometer W1 is electrically connected to pin 2 of the operational amplifier U33, pin 2 and pin 3 of the potentiometer W1 are both electrically connected to pin 3 of the operational amplifier U33, the two ends of the capacitor C177 are respectively electrically connected to pin 7 of the operational amplifier U33 and the signal input end of the addition output module 32, one end of the resistor R152 is grounded, and the other end is electrically connected to one end of the addition output module 32 connected to the capacitor C177.

[0071] like Fig.10 As shown, the addition output module 32 includes an operational amplifier U39 , and a pin 3 of the operational amplifier U39 is electrically connected to each piezoelectric ceramic sheet 2 to receive the collected data of all the piezoelectric ceramic sheets 2 .

[0072] The model of operational amplifier U39 can be AD8421, and its pin 3 is connected in series to five amplification compensation modules 35 through five resistors, and then the signal is added and output through pin 6.

[0073] As a preferred embodiment, it also includes a sound collector 6 and a ceramic substrate 7. The number of the sound collectors 6 is the same as the number of the piezoelectric ceramic sheets 2, and they are correspondingly arranged on each piezoelectric ceramic sheet 2. The sound collectors 6 correspond one-to-one to the collection holes to focus the sound waves. The number of the ceramic substrates 7 is the same as the number of the piezoelectric ceramic sheets 2. The ceramic substrates 7 are correspondingly arranged on the piezoelectric ceramic sheets 2 and are located between the piezoelectric ceramic sheets 2 and the flexible substrate 4.

[0074] The ceramic substrate is arranged between the piezoelectric ceramic sheet 2 and the flexible substrate 4, which provides mechanical support and enhances the stability of the entire sensor structure. Since the piezoelectric ceramic sheet 2 is usually thin and fragile, the ceramic substrate can help disperse the pressure and prevent the piezoelectric ceramic sheet 2 from breaking or being damaged due to external force or during installation.

[0075] The sound collector 6 is cone-shaped as a whole and is bonded and fixed between the housing 1 and the piezoelectric ceramic sheet 2, so that the sound collector 6 focuses the energy of the ultrasonic wave and concentrates the sound wave on the piezoelectric ceramic sheet 2, thereby improving the effective detection distance of the sensor by focusing the sound wave. Stronger sound waves mean that sufficient echo signals can be obtained at a farther distance, thereby improving the detection range of the sensor.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A broadband air ultrasonic sensor, characterized in that: It comprises a housing (1), at least two piezoelectric ceramic sheets (2), and a circuit board (3), wherein: A plurality of collection holes are provided on the shell (1); At least two piezoelectric ceramic sheets (2) are fixedly arranged in the housing (1) and respectively correspond to respective collection holes on the housing (1); the piezoelectric ceramic sheets (2) collect ultrasonic signals through the collection holes, and the frequency bands of at least two of the piezoelectric ceramic sheets (2) are different; The circuit board (3) is arranged on the housing (1), and the circuit board (3) comprises a frequency compensation module (31) and an addition output module (32). The frequency compensation module (31) and the addition output module (32) both have a signal input end and a signal output end. The piezoelectric ceramic sheet (2) is electrically connected to the signal input end of the frequency compensation module (31), and the signal output end of the frequency compensation module (31) is electrically connected to the signal input end of the addition output module (32). The frequency compensation module (31) is used to perform bandwidth compensation on piezoelectric ceramic sheets (2) of different frequency bands so that each discontinuous frequency band is combined to form a continuous frequency band. The addition output module (32) is used to perform addition output on the signals output by the frequency compensation module (31).

2. The broadband air ultrasonic sensor according to claim 1, characterized in that: It also includes a flexible substrate (4) and a sound absorbing sheet (5), wherein: The flexible substrate (4) is compositely arranged at the bottom of each piezoelectric ceramic sheet (2) to reduce mutual interference between piezoelectric ceramic sheets (2) with different resonance frequencies; The sound absorbing sheet (5) is compositely arranged on the bottom of the flexible substrate (4), and the sound absorbing sheet (5) is used to absorb sound energy during ultrasonic wave conduction.

3. The broadband air ultrasonic sensor according to claim 1, characterized in that: The circuit board (3) further comprises a program control module (33), the program control module (33) comprises a control output end, the frequency compensation module (31) comprises a control input end, and the control output end of the program control module (33) is electrically connected to the control input end of the frequency compensation module (31) to control the compensation frequency band of the frequency compensation module (31).

4. The broadband air ultrasonic sensor according to claim 1, characterized in that: The circuit board (3) further comprises an impedance matching module (34), wherein the impedance matching module (34) has a signal input end and a signal output end, wherein the signal input end is electrically connected to the piezoelectric ceramic sheet (2), and the signal output end is electrically connected to the signal input end of the frequency compensation module (31), wherein the frequency compensation module (31) is electrically connected to the piezoelectric ceramic sheet (2) via the impedance matching module (34), and wherein the impedance matching module (34) is used to perform impedance matching on a signal output by the piezoelectric ceramic sheet (2).

5. The broadband air ultrasonic sensor according to claim 1, characterized in that: The circuit board (3) further comprises an amplifying compensation module (35), the amplifying compensation module (35) having a signal input end and a signal output end, the signal input end of the amplifying compensation module (35) being electrically connected to the signal output end of the frequency compensation module (31), the signal output end of the amplifying compensation module (35) being electrically connected to the signal input end of the addition output module (32), and the addition output module (32) being electrically connected to the frequency compensation module (31) via the amplifying compensation module (35).

6. The broadband air ultrasonic sensor according to claim 1, characterized in that: The frequency bands of the piezoelectric ceramic sheets (2) are all different, and the frequency band difference between two piezoelectric ceramic sheets (2) with similar frequency bands is within a range of 5-15 kHz.

7. The broadband air ultrasonic sensor as claimed in claim 2, characterized in that: It also includes a sound collector (6) and a ceramic substrate (7), wherein: The number of the sound collectors (6) is the same as the number of the piezoelectric ceramic sheets (2), and they are correspondingly arranged on each piezoelectric ceramic sheet (2), and the sound collectors (6) correspond one-to-one to the collection holes to focus the sound waves; The number of the ceramic substrates (7) is the same as the number of the piezoelectric ceramic sheets (2); the ceramic substrates (7) are arranged on the piezoelectric ceramic sheets (2) in a one-to-one correspondence and are located between the piezoelectric ceramic sheets (2) and the flexible substrate (4).

8. The broadband air ultrasonic sensor as claimed in claim 4, characterized in that: The impedance matching module (34) includes an operational amplifier U32, a capacitor C172, a capacitor C175, a capacitor C173, a resistor R147, a resistor R148 and a resistor R149, wherein: Pin 4 of the operational amplifier U32 is electrically connected to the piezoelectric ceramic sheet (2), pin 5 and pin 8 are respectively connected to a positive and negative DC power supply, and pin 1 and pin 6 are grounded; One end of capacitor C172 is grounded, and the other end is electrically connected to pin 4 of operational amplifier U32; One end of capacitor C175 is grounded, and the other end is electrically connected to pin 4 of operational amplifier U32; One end of the capacitor C173 is electrically connected to the pin 7 of the operational amplifier U32, and the other end is electrically connected to the signal input end of the frequency compensation module (31); The two ends of the resistor R147 are electrically connected to the two ends of the capacitor C175 respectively; The two ends of the resistor R148 are electrically connected to the pin 2 and the pin 3 of the operational amplifier U32 respectively; One end of the resistor R149 is grounded, and the other end is electrically connected to one end of the capacitor C173 connected to the frequency compensation module (31).

9. The broadband air ultrasonic sensor as claimed in claim 5, characterized in that: The amplification compensation module (35) includes an operational amplifier U33, a resistor R151, a potentiometer W1, a capacitor C177 and a resistor R152, wherein: Pin 4 of the operational amplifier U33 is electrically connected to the signal output terminal of the frequency compensation module (31), pin 5 and pin 8 are respectively connected to the positive and negative DC power supplies, and pin 1 and pin 6 are grounded; The two ends of the resistor R151 are electrically connected to the pin 4 and the pin 1 of the operational amplifier U33 respectively; Pin 1 of the potentiometer W1 is electrically connected to pin 2 of the operational amplifier U33, and both pin 2 and pin 3 of the potentiometer W1 are electrically connected to pin 3 of the operational amplifier U33; The two ends of the capacitor C177 are electrically connected to the pin 7 of the operational amplifier U33 and the signal input end of the addition output module (32) respectively; One end of the resistor R152 is grounded, and the other end is electrically connected to one end of the capacitor C177 connected to the addition output module (32).

10. The broadband air ultrasonic sensor according to claim 1, characterized in that: The addition output module (32) comprises an operational amplifier U39, and a pin 3 of the operational amplifier U39 is electrically connected to each piezoelectric ceramic sheet (2) to receive the collected data of all the piezoelectric ceramic sheets (2).

Images