Piezoelectric sensor signal conditioner

Abstract

The utility model relates to signal conditioning technical field, and disclose piezoelectric sensor signal conditioner, including conditioner shell, and the conditioner circuit board fixed in the inside of conditioner shell, signal input module, signal conditioning module and signal output module are integrated on conditioner circuit board. The core signal conditioning function of the utility model is realized through RC circuit that resistance R and capacitor C constitute, and the charge signal integration equivalent conversion is converted into voltage signal through capacitor C, and resistance R provides the discharge circuit for this charge, and its resistance value determines the low frequency response of circuit, and the whole conversion process does not need external to provide any form power supply, realizes passive work, the utility model completely gives up power module, so that the conditioner can be used as soon as possible in any need to deploy piezoelectric sensor occasion, need not consider the wiring power supply or battery replacement problem, especially suitable in remote, mobile or long -term monitoring etc. inconvenient power supply scene uses.

Description

Technical Field

[0001] This utility model belongs to the field of signal conditioning technology, and specifically relates to a piezoelectric sensor signal conditioner. Background Technology

[0002] Piezoelectric sensors are often used to measure force, acceleration, vibration, etc. The principle is that when a piezoelectric material is deformed under force, it will output an electric charge signal. This electric charge signal is proportional to the amount of deformation of the piezoelectric material. By measuring the amount of electric charge output by the sensor, the amount of deformation of the piezoelectric material can be obtained, and thus the magnitude of the force or acceleration being measured can be obtained.

[0003] In the existing technology, since piezoelectric sensors output charge signals, most signal acquisition devices do not have the ability to acquire charge signals. Furthermore, charge signals are easily affected by interference and attenuated during transmission, which makes it impossible for the acquisition system to accurately and effectively measure the charge signals output by the piezoelectric sensor.

[0004] Therefore, for the reasons mentioned above, it is necessary to convert the charge signal output by the piezoelectric sensor into a voltage signal. However, the existing charge conditioner circuit structures are too complex and require power supply, which increases the size of the signal conditioner structure and limits its application scenarios.

[0005] Currently, invention patent CN113342202A discloses an anti-interference analog signal conditioning circuit for acoustic wave touchscreens, belonging to the field of acoustic wave touchscreen technology. It includes an LC filter differential amplifier circuit and a VGA circuit. The LC filter differential amplifier circuit amplifies the input signal and filters and selects the frequency of the amplified signal during gain amplification to suppress interference signals. The VGA circuit is connected to both the LC filter differential amplifier circuit and the control voltage, forming a common negative feedback network for the LC filter differential amplifier circuit, used to adjust the gain factor. This further enhances the anti-interference capability of the acoustic wave touchscreen while maintaining high filtering frequency selection characteristics over a wide dynamic range.

[0006] The circuit structure disclosed above is still relatively complex and requires constant current source power supply, making it cumbersome to use. Complex wiring will introduce parasitic capacitance and inductance, leading to signal distortion. Furthermore, the increased number of components will lead to an increase in the failure rate.

[0007] Furthermore, the conditioner is an active structure that requires power, and it needs to be connected to a power source or have a built-in battery when in use, which limits its application scenarios;

[0008] Meanwhile, existing conditioners are bulky and inconvenient to carry. When using hundreds or thousands of piezoelectric sensors at the same time, an equal number of signal conditioners must be used. The large size of a single conditioner limits its portability. Utility Model Content

[0009] The purpose of this invention is to address the shortcomings of existing technologies by proposing a piezoelectric sensor signal conditioner.

[0010] To achieve the above objectives, this utility model adopts the following technical solution: a piezoelectric sensor signal conditioner, including a conditioner housing and a conditioner circuit board fixed inside the conditioner housing; the conditioner circuit board integrates a signal input module, a signal conditioning module, and a signal output module; the signal input module includes an FPC connector, which has a positive pin and a negative pin, the positive pin being used to connect to the positive lead of the piezoelectric sensor and serve as the signal input terminal, and the negative pin being used to connect to the negative lead of the piezoelectric sensor; the signal conditioning module includes a resistor R and a capacitor C; one end of the resistor R is connected to the positive pin of the FPC connector, and the other end of the resistor R is connected to one end of the capacitor C and the input terminal of the signal output module; the other end of the capacitor C is connected to the negative pin of the FPC connector and the ground terminal of the signal output module.

[0011] Preferably, the signal output module includes a coaxial cable and an RF connector.

[0012] Preferably, the coaxial cable includes an inner core wire and an outer shielding layer; the RF connector includes a shell and a pin; the inner core wire is connected to the pin, and the outer shielding layer is connected to the shell.

[0013] Preferably, the inner core of the coaxial cable is connected to the common connection terminal of the resistor R and the capacitor C, and the outer shielding layer of the coaxial cable is connected to the negative pin of the FPC connector.

[0014] Preferably, the conditioner circuit board is an array circuit board composed of multiple conditioning units.

[0015] In summary, this utility model has the following beneficial effects:

[0016] 1. The core signal conditioning function of this utility model is achieved by an RC circuit consisting of a resistor R and a capacitor C. This circuit utilizes the charge output characteristics of the piezoelectric sensor itself, and converts the charge signal into a voltage signal through the capacitor C. The resistor R provides a discharge circuit for the charge, and its resistance value determines the low-frequency response of the circuit. The entire conversion process does not require any external power supply, achieving true passive operation. Compared with the corresponding patent CN113342202A, this utility model completely eliminates the power supply module, allowing the conditioner to be plugged and played in any situation where a piezoelectric sensor needs to be deployed, without having to consider wiring, power supply or battery replacement issues. It is particularly suitable for use in scenarios where power supply is inconvenient, such as remote, mobile or long-term monitoring.

[0017] 2. Since the core circuit of this utility model consists of only two miniature surface-mount resistors and capacitors, the entire conditioner can be made very compact. The extremely simple circuit structure allows dozens or even hundreds of independent conditioning units to be integrated on the same PCB board with high density. Each conditioning unit corresponds to an independent sensor channel, realizing parallel conditioning of array signals. This solves the problem of large size of conditioners in large-scale sensor networks. Traditional solutions require stacking hundreds of independent and bulky conditioning boxes, while this utility model only needs a compact integrated PCB board to handle all channels, greatly improving portability and system integration.

[0018] 3. This utility model utilizes an FPC connector as the interface in the signal input module. This connector is specifically designed for connecting flexible printed circuits or ribbon cables. Sensors using FPC leads can be directly plugged in and out, providing a convenient and reliable connection. Compared to traditional soldering or screw crimping methods, it offers a standardized, quick-connect mechanical and electrical interface, firmly connecting the flexible sensor leads to the rigid conditioner circuit board. Traditional conditioners typically use solder wire or universal terminal blocks, which are prone to damage, poor contact, or unstable connection when handling the flexible and fragile FPC leads. The FPC connector design of this utility model solves this problem, improving the convenience, repeatability, and reliability of the connection, and reducing the difficulty and technical risks of on-site installation. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0020] Figure 2 This is a schematic diagram of the FPC connector of this utility model;

[0021] Figure 3 This is a schematic diagram of the conditioner circuit board of this utility model;

[0022] Figure 4 This is a schematic diagram of the resistor R of this utility model;

[0023] Figure 5 This is a schematic diagram of each module of the present invention;

[0024] Figure 6 This is a schematic diagram of the circuit board for the unit array sensor conditioner of this utility model.

[0025] Figure label:

[0026] 1. RF connector; 2. Coaxial cable;

[0027] 3. Conditioner housing;

[0028] 4. FPC connector;

[0029] 5. Conditioner circuit board;

[0030] 6. Resistance R;

[0031] 7. Capacitor C;

[0032] 8. Signal output module;

[0033] 9. Signal conditioning module;

[0034] 10. Signal input module. Detailed Implementation

[0035] To make the technical means, creative features, and achieved objectives and effects of this utility model easier to understand, the present utility model is further described below with reference to specific embodiments and accompanying drawings. However, the following embodiments are merely preferred embodiments of this utility model and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described in the implementation plan without creative effort are all within the protection scope of this utility model.

[0036] The specific embodiments of this utility model are described below with reference to the accompanying drawings:

[0037] Example 1:

[0038] refer to Figures 1-5 A piezoelectric sensor signal conditioner includes a conditioner housing 3 and a conditioner circuit board 5 fixed inside the conditioner housing 3. The conditioner circuit board 5 integrates a signal input module 10, a signal conditioning module 9, and a signal output module 8. The signal input module 10 includes an FPC connector 4 with positive and negative pins. The positive pin is used to connect to the positive lead of the piezoelectric sensor and serve as the signal input terminal, while the negative pin is used to connect to the negative lead of the piezoelectric sensor. The signal conditioning module 9 includes a resistor R6 and a capacitor C7. One end of the resistor R6 is connected to the positive pin of the FPC connector 4, and the other end of the resistor R6 is connected to one end of the capacitor C7 and the input terminal of the signal output module 8. The other end of the capacitor C7 is connected to the negative pin of the FPC connector 4 and the ground terminal of the signal output module 8.

[0039] Specifically, the system includes a central conditioning housing 3 for encapsulating and protecting internal components, and a conditioning circuit board 5 mounted inside the housing 3 by means of clips or screws. The conditioning circuit board 5 integrates a signal input module 10, a signal conditioning module 9, and a signal output module 8. The signal input module 10 includes an FPC connector 4 for connecting a flexible printed circuit (FPC) or a flexible flat cable. The FPC connector 4 has a positive pin for transmitting a positive charge signal and a negative pin for connecting to a reference ground. The positive pin is used for mechanical connection and electrical connection with the positive lead of an external piezoelectric sensor, thus serving as the signal input terminal of the entire conditioning structure. The negative pin is used for connection with the external piezoelectric sensor... The negative lead is mechanically connected and electrically connected; the signal conditioning module 9 consists of a surface-mount resistor R6 and a surface-mount capacitor C7, which form a passive RC charge-to-voltage conversion circuit; one end of the resistor R6 is electrically connected to the positive pin of the FPC connector 4 to provide a discharge path for the charge generated by the piezoelectric sensor and to set the time constant of the circuit; the other end of the resistor R6 is electrically connected to one end of the capacitor C7 to form a common node, which is also electrically connected to the input terminal of the signal output module 8; the other end of the capacitor C7 is electrically connected to the negative pin of the FPC connector 4 to receive the charge signal and integrate it into a voltage signal; this connection point is also electrically connected to the ground terminal of the signal output module 8.

[0040] The signal conditioning module 9, consisting of a surface-mount resistor R6 and a surface-mount capacitor C7, enables the conversion of charge signals into voltage signals without external power supply, achieving passivity and high reliability. The signal input module 10, including an FPC connector 4 for connecting to a flexible printed circuit (FPC) and positive and negative pins for mechanical and electrical connection with the piezoelectric sensor leads, provides a convenient, stable, and standardized connection to the flexible piezoelectric sensor, improving installation efficiency and reliability. This design offers a completely passive, extremely simplified, and reliable piezoelectric sensor signal conditioner. This design fundamentally eliminates dependence on external power, significantly improving reliability and expanding application scenarios. Furthermore, its interface, specifically designed for flexible sensors, solves the problems of easily damaged leads and poor contact in traditional connection methods.

[0041] The signal output module 8 includes a coaxial cable 2 and an RF connector 1. The coaxial cable 2 includes an inner core wire and an outer shielding layer; the RF connector 1 includes a shell and a pin; the inner core wire is connected to the pin, and the outer shielding layer is connected to the shell.

[0042] Specifically, the signal output module 8 includes a coaxial cable 2 for signal transmission and an RF connector 1 for interfacing with an external signal acquisition device. The input end of the coaxial cable 2 is connected to the common node and ground terminal on the conditioner circuit board 5, and the output end is connected to the RF connector 1. The coaxial cable 2 includes an inner core wire for transmitting the conditioned voltage signal and an outer shielding layer wrapped around the inner core wire for electromagnetic shielding and grounding. The RF connector 1 includes a metal shell connected to the outer shielding layer and a core pin connected to the inner core wire.

[0043] By incorporating the technical features of a coaxial cable 2 for signal transmission and an RF connector 1 for interfacing with an external signal acquisition device, the signal output module 8 achieves shielded transmission and standardized interface output. Further defining the technical features of the coaxial cable 2 (including an inner core and an outer shielding layer) and the RF connector 1 (including a shell and pins and their connection relationship), it specifically achieves interference-resistant signal transmission and a robust electrical and mechanical connection with the acquisition device. This provides a standard signal output scheme with strong interference resistance and a stable connection, ensuring that the conditioned weak voltage signal can be transmitted to the remote signal acquisition device with high quality and low loss, and facilitating compatibility with the standard interface of the acquisition device.

[0044] The inner core of coaxial cable 2 is connected to the common connection terminal of resistor R6 and capacitor C7, and the outer shield of coaxial cable 2 is connected to the negative pin of FPC connector 4.

[0045] Specifically, the inner core wire of coaxial cable 2 is soldered or crimped to the common node of resistor R6 and capacitor C7 inside the conditioner for transmitting the converted voltage signal; the outer shielding layer of coaxial cable 2 is connected to a grounding point inside the conditioner together with the negative pin of FPC connector 4 and the grounding terminal of capacitor C7.

[0046] By connecting the inner core wire of coaxial cable 2, the common node connection, the outer shielding layer, the negative pin of FPC connector 4, and the grounding terminal of capacitor C7 to a single grounding point, low-noise signal transmission and a unified grounding reference point are achieved, ensuring signal purity. This optimizes the grounding and signal transmission path design inside the conditioner, ensuring signal integrity. The single-point grounding principle avoids noise introduced by ground loops, further improving the quality of signal output and anti-interference capability.

[0047] Conditioner circuit board 5 is an array circuit board composed of multiple conditioning units.

[0048] Specifically, the conditioner circuit board 5 is a printed circuit board on which multiple identical signal input modules 10, signal conditioning modules 9 and signal output modules 8 can be arranged in parallel to form a multi-channel array conditioner circuit board for simultaneously processing signals from multiple piezoelectric sensors.

[0049] By arranging multiple identical modules in parallel on the conditioner circuit board 5 to form a multi-channel array conditioner circuit board, multiple independent conditioning units are integrated into a single circuit board with high density. This provides a compact and efficient parallel signal conditioning solution for array sensors, offering extremely high system integration and scalability. It is particularly suitable for large-scale sensor array applications, greatly saving space, simplifying the wiring complexity and overall size of multi-channel systems, and solving the portability and cost issues in large-scale deployment.

[0050] Example 2:

[0051] refer to Figures 1-5 Staff members used the structure disclosed in this utility model in a bridge structure monitoring system.

[0052] This system requires the deployment of hundreds of piezoelectric sensor arrays in key bridge components such as piers, inside box girders, and beneath the bridge deck to monitor the vibration and strain signals generated by the bridge under vehicle loads, wind loads, and environmental influences in real time over a long period. Most of these sensors are flexible piezoelectric film sensors based on polyvinylidene fluoride (PVDF) material, with 5mm wide flexible printed circuit (FPC) cables as leads. In specific implementation, a PVDF piezoelectric film sensor with a sensitivity of approximately 10 picocoulombs per Newton is selected, and its FPC lead is directly inserted into a 0.5mm pitch 24-pin Hirose FH12 series FPC connector in the conditioner signal input module of this invention, achieving a fast and reliable electrical and mechanical connection. The core components of the signal conditioning module are 0805-package surface-mount resistors manufactured by Murata Manufacturing Co., Ltd., with a resistance of 10 megohms, and surface-mount capacitors of the same package, with a capacitance of 100 picofarads. Together, they form an RC charge-to-voltage conversion network on the conditioner circuit board, converting the charge signal output by the sensor into a voltage signal with an amplitude of approximately 0 to 5 volts. The low-frequency cutoff frequency of this circuit is approximately 0.16 Hz, effectively capturing low-frequency vibrations of the bridge. The signal output module uses RG174 coaxial cable with a characteristic impedance of 50 ohms. Its length can be cut from 1 to 20 meters according to the needs of on-site wiring. The inner core wire of the cable is soldered to a common node, and the outer shielding layer, along with the negative pin of the FPC connector and the capacitor grounding terminal, is connected to the grounding copper foil on the circuit board. The RF connector uses a common Q9 type BNC connector, with its pin crimped to the inner core wire of the coaxial cable. The outer shell is tightened to the outer shielding layer. Finally, the BNC connector is plugged into the BNC interface of the pre-conditioning module of the NI PXIe acquisition system deployed in the pier monitoring box. The entire conditioner circuit board is made of FR4 material and measures 100 mm by 80 mm. It integrates 16 identical conditioning units in a grid pattern, which can process 16 sensor signals simultaneously. All conditioning units are sealed in a hollow shell made of ABS engineering plastic with an IP65 protection rating to adapt to the harsh environment of wet vibration at the bridge site.

[0053] Through this invention, hundreds of sensor signals can be passively, faithfully, and with anti-interference capabilities converted into standard voltage signals and transmitted to a central acquisition station 50 meters away, providing a continuous and high-quality data foundation for bridge structural safety assessment.

[0054] The working principle of this invention is as follows: When the piezoelectric sensor is subjected to force, acceleration, or vibration, it outputs a weak charge signal. This charge signal is transmitted to the FPC connector of the signal input module through the sensor's flexible lead wire. The signal conditioning module performs an equivalent conversion of the charge signal through a passive RC circuit consisting of a resistor and a capacitor. The capacitor acts as an integrator, converting the charge signal into a voltage signal, while the resistor is connected in parallel across the capacitor to provide a discharge path for the charge and determine the low-frequency response time constant of the circuit, thus forming a simple and reliable first-order high-pass filter. The converted voltage signal is transmitted through the coaxial cable of the signal output module. The inner core wire transmits the signal while the outer shielding layer is reliably grounded, effectively suppressing external electromagnetic interference. The RF connector at the end of the coaxial cable finally outputs the conditioned voltage signal to an external signal acquisition system in a standard interface format. This achieves the goal of converting the charge signal of the piezoelectric sensor into a voltage signal with high fidelity and anti-interference without external power supply and transmitting it over long distances.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A piezoelectric sensor signal conditioner, characterized in that: Includes a conditioner housing (3) and a conditioner circuit board (5) fixed inside the conditioner housing (3); The conditioner circuit board (5) integrates a signal input module (10), a signal conditioning module (9), and a signal output module (8); The signal input module (10) includes an FPC connector (4), which has a positive pin and a negative pin. The positive pin is used to connect to the positive lead of the piezoelectric sensor and serve as a signal input terminal, and the negative pin is used to connect to the negative lead of the piezoelectric sensor. The signal conditioning module (9) includes a resistor R (6) and a capacitor C (7); One end of the resistor R (6) is connected to the positive pin of the FPC connector (4), and the other end of the resistor R (6) is connected to one end of the capacitor C (7) and the input terminal of the signal output module (8). The other end of the capacitor C (7) is connected to the negative pin of the FPC connector (4) and the ground terminal of the signal output module (8).

2. The piezoelectric sensor signal conditioner according to claim 1, characterized in that: The signal output module (8) includes a coaxial cable (2) and an RF connector (1).

3. The piezoelectric sensor signal conditioner according to claim 2, characterized in that: The coaxial cable (2) includes an inner core wire and an outer shielding layer; the radio frequency connector (1) includes a shell and a pin; the inner core wire is connected to the pin, and the outer shielding layer is connected to the shell.

4. The piezoelectric sensor signal conditioner according to claim 3, characterized in that: The inner core of the coaxial cable (2) is connected to the common connection terminal of the resistor R (6) and the capacitor C (7), and the outer shielding layer of the coaxial cable (2) is connected to the negative pin of the FPC connector (4).

5. The piezoelectric sensor signal conditioner according to claim 1, characterized in that: The conditioner circuit board (5) is an array circuit board composed of multiple conditioning units.

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