A circuit based on a piezoelectric impact sensor

Abstract

The utility model discloses a kind of circuit based on piezoelectric impact sensor, including power module, piezoceramics module, amplifier circuit, reference voltage circuit, filter circuit and output drive circuit, each module is electrically connected by wire, power module includes bidirectional transient voltage suppression diode TVS1, schottky diode D1, power filter unit and low dropout linear regulator U1, the piezoceramics module includes piezoceramics, amplifier circuit includes four-channel operational amplifier U3, charge amplifier and voltage amplifier, reference voltage circuit includes voltage reference source chip U2, filter circuit includes resistance R8 and capacitor C9, output drive circuit is constituted by operational amplifier U3D, the utility model, the differential processing framework formed by charge amplifier and voltage amplifier, common-mode interference on transmission line between piezoceramics and amplifier circuit can be effectively inhibited, cooperate with the low-noise design of power filter unit and reference voltage circuit, significantly reduce sensor output noise.

Description

Technical Field

[0001] This utility model relates to the technical field of piezoelectric impact sensors, and in particular to a circuit based on a piezoelectric impact sensor. Background Technology

[0002] Piezoelectric impact sensors are detection devices that convert mechanical energy into electrical signals using the piezoelectric effect. Their core components include a piezoelectric element, signal processing circuitry, and a power supply unit. They are widely used in automotive safety systems, aerospace equipment vibration monitoring, industrial machinery impact early warning, and logistics cargo impact recording. Current circuit designs for piezoelectric impact sensors typically employ a "piezoelectric element, single-ended amplifier circuit, simple power supply" architecture: the piezoelectric element converts the impact mechanical energy into a charge signal, which is then directly amplified by a single-ended operational amplifier. An external power supply, after simple voltage division or rectification, directly powers the circuit. Some circuits even omit the reference voltage unit, relying on the power supply's own voltage as the signal bias.

[0003] However, existing signal processing uses a single-ended amplification architecture, which cannot suppress common-mode interference on the transmission line between the piezoelectric element and the amplification circuit, resulting in a significant increase in sensor output noise. The power supply unit lacks protection and stability design: there are no transient overvoltage protection devices, making it easy to damage the subsequent circuits due to external power surges; there is no reverse connection protection design, and the core chip will be burned out directly when the positive and negative terminals of the power supply are reversed; and no low dropout linear regulator (LDO) is used for voltage conversion, so external power supply voltage fluctuations are directly transmitted to the amplification circuit, further aggravating signal distortion; there is a lack of a high-precision voltage reference source, and the signal bias depends on the unstable power supply voltage, resulting in poor linearity of the sensor output amplitude, which cannot meet the high-precision detection requirements of manufacturing scenarios.

[0004] To address this issue, we propose a circuit based on a piezoelectric impact sensor. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a circuit based on a piezoelectric impact sensor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A circuit based on a piezoelectric impact sensor includes a power supply module, a piezoelectric ceramic module, an amplifier circuit, a reference voltage circuit, a filter circuit, and an output drive circuit. The power supply module is connected to the amplifier circuit through the reference voltage circuit. The positive and negative terminals of the piezoelectric ceramic module are both connected to the amplifier circuit. The amplifier circuit, the filter circuit, and the output drive circuit are connected in sequence. The power module includes a bidirectional transient suppression diode TVS1, a Schottky diode D1, a power filter unit, and a low dropout linear regulator U1, which are used to achieve protection, filtering, and stable conversion of external power supply. The piezoelectric ceramic module includes a piezoelectric ceramic, with the positive terminal of the piezoelectric ceramic being piezoelectric ceramic+ and the negative terminal being piezoelectric ceramic-, used to convert impact mechanical energy into an electric charge signal; The amplifier circuit includes a four-channel operational amplifier U3, a charge amplifier, and a voltage amplifier. The four-channel operational amplifier U3 is divided into four independent operational amplifiers: operational amplifier U3A, operational amplifier U3B, operational amplifier U3C, and operational amplifier U3D, which are used to convert charge signals into voltage signals and perform differential amplification. The reference voltage circuit includes a voltage reference source chip U2, which provides a high-precision DC bias voltage. The filter circuit includes a resistor R8 and a capacitor C9, which are used to filter out high-frequency noise in the amplified signal. The output drive circuit is composed of an operational amplifier U3D, which is used to reduce the output impedance and improve the load capacity. All modules are electrically connected by wires.

[0007] Preferably, the bidirectional transient suppression diode TVS1 is connected in parallel between the positive terminal VCC and the negative terminal GND of the external power supply, the Schottky diode D1 is connected in series between the positive terminal VCC and the power supply filter unit, the output terminal of the power supply filter unit is connected to the input terminal of the low dropout linear regulator U1, and the output terminal of the low dropout linear regulator U1 outputs the supply voltage VDD.

[0008] Preferably, the charge amplifier is composed of operational amplifier U3A, capacitor C13, resistor R9 and operational amplifier U3B, capacitor C14, resistor R10. The output terminal of operational amplifier U3A is fed back to its inverting input terminal through capacitor C13, and resistor R9 is connected in parallel across capacitor C13. The output terminal of operational amplifier U3B is fed back to its inverting input terminal through capacitor C14, and resistor R10 is connected in parallel across capacitor C14.

[0009] Preferably, the voltage amplifier comprises an operational amplifier U3C, resistors R2-R7, and capacitors C7 and C8. Resistor R2 is connected in series between the inverting input and output of operational amplifier U3C; resistor R3 is connected in parallel between the inverting input of operational amplifier U3C and the negative terminal of the external power supply GND; resistor R4 is connected in series between the non-inverting input of operational amplifier U3C and the reference voltage VREF; resistor R5 is connected in parallel between the non-inverting input of operational amplifier U3C and the negative terminal of the external power supply GND; resistor R6 is connected in series between the output of operational amplifier U3A and the negative terminal of the external power supply GND; and resistor R7 is connected in series between the output of operational amplifier U3B and the negative terminal of the external power supply GND.

[0010] Preferably, a decoupling capacitor C5 is connected in parallel to the input terminal of the voltage reference source chip U2 of the reference voltage circuit, and a bypass capacitor C6 is connected in parallel to the output terminal of the voltage reference source chip U2.

[0011] Preferably, the resistor R8 and capacitor C9 of the filter circuit constitute a low-pass filter unit.

[0012] Preferably, the operational amplifier U3D of the output drive circuit is configured as a voltage follower.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: The differential processing architecture composed of the charge amplifier and voltage amplifier in this invention can effectively suppress common-mode interference on the transmission line between the piezoelectric ceramic and the amplifier circuit. Combined with the low-noise design of the power supply filter unit and the reference voltage circuit, it significantly reduces the sensor output noise. The LDO conversion unit provides a stable power supply voltage VDD to avoid the influence of power supply fluctuations on the amplifier circuit. The voltage reference source U2 outputs a high-precision reference voltage VREF as a signal bias to ensure the linearity of the charge-to-voltage conversion and differential amplification process. After actual debugging, the linearity of the output amplitude of this circuit can be stably controlled within 0.5%, which is far better than the linearity level of more than 1% of existing products. The transient protection unit and reverse connection protection unit can resist transient overvoltage and reverse power connection, avoiding damage to the core components of the circuit. The operational amplifier U3D voltage follower in the output drive circuit reduces the output impedance and improves the load capacity, which can be directly adapted to a variety of data acquisition devices without the need for an additional drive module. Attached Figure Description

[0014] Figure 1 This is the overall block diagram of the impact sensor circuit of this utility model; Figure 2 This is the circuit diagram of the impact sensor of this utility model; Figure 3 This is a circuit diagram of the power module and its auxiliary structures of this utility model; Figure 4 This is a circuit diagram of the piezoelectric ceramic module, amplifier circuit, and their associated structures of this utility model.

[0015] In the diagram: 1-Power supply module, 2-Piezoelectric ceramic module, 3-Amplifier circuit, 4-Reference voltage circuit, 5-Filter circuit, 6-Output drive circuit. Detailed Implementation

[0016] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0017] In the description of this utility model, "multiple" means two or more, unless otherwise explicitly specified.

[0018] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0020] Reference Figure 1-4 A circuit based on a piezoelectric impact sensor includes a power supply module 1 for protection, filtering, and stabilization of external power supply; a piezoelectric ceramic module 2 for converting impact mechanical energy into charge signal; an amplifier circuit 3 for converting charge signal into voltage signal and differentially amplifying it; a reference voltage circuit 4 for providing high-precision DC bias voltage; a filter circuit 5 for filtering out high-frequency noise in the amplified signal; and an output drive circuit 6 for reducing output impedance and improving load capacity. The modules are electrically connected by wires. The power supply module 1 is connected to the amplifier circuit 3 through the reference voltage circuit 4. The positive and negative terminals of the piezoelectric ceramic module 2 are both connected to the amplifier circuit 3. The amplifier circuit 3, the filter circuit 5, and the output drive circuit 6 are connected in sequence. Power module 1 includes a bidirectional transient voltage suppressor diode (TVS1), which is used for power protection and to protect downstream circuits. When an abnormal overvoltage occurs in the circuit and reaches the TVS (avalanche) breakdown voltage, the TVS quickly changes from a high resistance state to a low resistance state, discharging the instantaneous overcurrent caused by the abnormal overvoltage to ground, while clamping the abnormal overvoltage to a low level, thereby protecting the downstream circuits from damage caused by the abnormal overvoltage. When the abnormal overvoltage disappears, the TVS resistance returns to a high resistance state. Schottky diode D1 is used for reverse connection protection of the power supply. When the positive and negative terminals of the power supply are connected normally, Schottky diode D1 conducts in the forward direction and the circuit works normally; when the positive and negative terminals of the power supply are reversed, Schottky diode D1 is reverse cut off, protecting the downstream components from damage. The power supply filtering unit consists of inductor L1, capacitor C1, and capacitor C2, employing a π-type filter architecture. Inductor L1 and capacitors C1 and C2 form the filter circuit, filtering the externally input power supply. The cutoff frequency is... A bidirectional transient suppression diode TVS1 is connected in parallel between the positive terminal VCC and the negative terminal GND of the external power supply to form a transient protection circuit. A Schottky diode D1 is connected in series between the positive terminal VCC of the external power supply and the power filter unit. It is installed in series, with its anode welded to the positive terminal VCC of the external power supply and its cathode connected to one end of the inductor L1 of the power filter unit through a wire. The output terminal of the power filter unit is connected to the input terminal of the low dropout linear regulator U1. A decoupling capacitor C3 is connected in parallel to the input terminal of the low dropout linear regulator U1. One end of the decoupling capacitor C3 is connected to the input pin of the low dropout linear regulator U1, and the other end is grounded. A bypass capacitor C4 is connected in parallel to the output terminal of the low dropout linear regulator U1. One end of the bypass capacitor C4 is connected to the output pin of the low dropout linear regulator U1, and the other end is grounded. The output terminal of the low dropout linear regulator U1 outputs the internal supply voltage VDD, which provides a stable power supply for the amplifier circuit 3 and the reference voltage circuit 4. The positive terminal of the external power supply VCC is used as the input of the low dropout linear regulator U1 after protection and filtering. Piezoelectric ceramic module 2 includes a piezoelectric ceramic. The positive terminal of the piezoelectric ceramic is piezoelectric ceramic+, and the positive input terminal of the piezoelectric ceramic is charged with Q+. The amplification factor is -1 / C13, and the corresponding output is... The negative terminal is a piezoelectric ceramic electrode, the negative terminal input of the piezoelectric ceramic electrode is charged with Q-, the amplification factor is -1 / C14, and the corresponding output is... The piezoelectric ceramic 2 is fixed to the impact receiving surface of the sensor housing with epoxy resin. Its positive lead-out piezoelectric ceramic + is connected to the inverting input terminal of the operational amplifier U3A in the amplifier circuit 3 through a shielded wire, and its negative lead-out piezoelectric ceramic - is connected to the inverting input terminal of the operational amplifier U3B in the amplifier circuit 3 through a shielded wire. Amplifier circuit 3 includes a four-channel operational amplifier U3, a charge amplifier, and a voltage amplifier. Operational amplifier U3 consists of four independent operational amplifiers: operational amplifier U3A, operational amplifier U3B, operational amplifier U3C, and operational amplifier U3D. The charge amplifier is composed of operational amplifier U3A, capacitor C13, and resistor R9, and operational amplifier U3B, capacitor C14, and resistor R10. The output of operational amplifier U3A is directly connected to its inverting input through capacitor C13. Resistor R9 is connected in parallel across capacitor C13, forming a closed-loop charge amplification circuit. Capacitor C13 and resistor R9 constitute a high-pass filter at the positive input of the piezoelectric ceramic, with a cutoff frequency of [missing value]. The output of operational amplifier U3B is fed back to its inverting input via capacitor C14. Resistor R10 is connected in parallel across capacitor C14. Capacitor C14 and resistor R10 form a high-pass filter at the negative input of the piezoelectric ceramic amplifier, with a cutoff frequency of [missing value]. The voltage amplifier consists of operational amplifier U3C, resistors R2-R7, and capacitors C7 and C8. It is used to convert differential signals into single-ended signals. Capacitors C7 and C8 filter out the DC bias after charge amplification of the piezoelectric ceramic. Resistor R2 is connected in series between the inverting input and output of operational amplifier U3C to form a negative feedback loop. Resistor R3 is connected in parallel between the inverting input of operational amplifier U3C and the negative terminal of the external power supply GND. Resistor R4 is connected in series between the non-inverting input of operational amplifier U3C and the reference voltage VREF. Resistor R5 is connected in parallel between the non-inverting input of operational amplifier U3C and the negative terminal of the external power supply GND. Resistor R6 is connected in series between the output of operational amplifier U3A and the negative terminal of the external power supply GND. Resistor R7 is connected in series between the output of operational amplifier U3B and the negative terminal of the external power supply GND, forming a signal voltage divider stabilization loop. For V+, the output of the charge amplifier is: For V-, the output of the charge amplifier is: For the reference voltage VREF, the charge amplifier output is: ; The total output of the voltage amplifier is: + ; When R2=R3=R4=R5=R6=R7, ; The total output of the piezoelectric ceramic after passing through the charge amplifier and voltage amplifier is: ; Reference voltage circuit 4 includes a voltage reference source chip U2, whose input is the supply voltage VDD, with a decoupling capacitor C5 connected in parallel at the input. Its output is the reference voltage VREF, with a bypass capacitor C6 connected in parallel at the output. Filter circuit 5 includes a resistor R8 and a capacitor C9. The resistor R8 and capacitor C9 in filter circuit 5 form a low-pass filter unit used to filter out interference and noise, with a cutoff frequency of [missing information]. The output drive circuit 6 includes an operational amplifier U3D, which forms a voltage follower to reduce output impedance and improve load capacity.

[0021] Based on the above structure, the present invention has the following embodiments: The external power supply is connected from the positive terminal VCC and the negative terminal GND. First, it undergoes transient overvoltage protection via a bidirectional transient voltage suppressor diode (TVS1). If a surge voltage occurs, the TVS1 quickly breaks down to discharge current, clamping the voltage within a safe range. Then, the power supply is protected against reverse connection via a Schottky diode D1, ensuring unidirectional current conduction. Next, a π-type filter circuit consisting of inductor L1, capacitor C1, and capacitor C2 filters out power frequency interference and high-frequency ripple. Finally, the voltage is regulated to 3.3V by a low-dropout linear regulator U1. The supply voltage VDD is further smoothed by decoupling capacitor C3 and bypass capacitor C4, providing a stable and clean power supply for amplifier circuit 3 and reference voltage circuit 4. Reference voltage circuit 4's U2 starts under the supply voltage VDD and outputs a 3.3V reference voltage VREF after internal reference source calibration. Decoupling capacitor C5 and bypass capacitor C6 filter out noise at the input and output terminals, respectively, so that the voltage ripple of reference voltage VREF is ≤1mV. Reference voltage VREF is transmitted through wires to the non-inverting input terminals of operational amplifiers U3A and U3B and the bias node of operational amplifier U3C in amplifier circuit 3, providing a stable DC bias reference for subsequent signal amplification. When external impact mechanical energy acts on the piezoelectric ceramic of piezoelectric ceramic module 2, the ceramic sheet generates a charge signal due to the piezoelectric effect, with the positive terminal outputting Q+ and the negative terminal outputting Q-. Q+ is transmitted through shielded wires to the inverting input terminal of operational amplifier U3A and Q- is transmitted to... The inverting input of operational amplifier U3B converts mechanical energy into a charge signal. The shielding layer of the shielded wire effectively avoids interference coupling during transmission. After the charge signal enters amplifier circuit 3, it is first converted into voltage signals V+ and V- by a charge amplifier consisting of operational amplifier U3A, capacitor C13, resistor R9, operational amplifier U3B, capacitor C14, and resistor R10. At the same time, a high-pass filter removes low-frequency drift. Subsequently, V+ and V- are isolated and DC biased by capacitors C7 and C8, and then input to a differential amplifier consisting of operational amplifier U3C. The single-ended signal output by operational amplifier U3C enters filter circuit 5. After passing through a low-pass filter consisting of resistor R8 and capacitor C9, high-frequency noise and spike interference are removed, and the effective low-frequency signal is retained, making the signal waveform smoother and reducing the noise amplitude to less than 5% of the effective signal. The filtered effective signal is then input to a voltage follower consisting of operational amplifier U3D.

[0022] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

[0023] In the description of this utility model, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

Claims

1. A circuit based on a piezoelectric impact sensor, characterized in that, It includes a power supply module (1), a piezoelectric ceramic module (2), an amplifier circuit (3), a reference voltage circuit (4), a filter circuit (5), and an output drive circuit (6). The power supply module (1) is connected to the amplifier circuit (3) through the reference voltage circuit (4). The positive and negative terminals of the piezoelectric ceramic module (2) are both connected to the amplifier circuit (3). The amplifier circuit (3), the filter circuit (5), and the output drive circuit (6) are connected in sequence. The power module (1) includes a bidirectional transient suppression diode TVS1, a Schottky diode D1, a power filter unit and a low dropout linear regulator U1, which are used to realize the protection, filtering and stable conversion of external power supply; The piezoelectric ceramic module (2) includes a piezoelectric ceramic, with the positive terminal of the piezoelectric ceramic being piezoelectric ceramic+ and the negative terminal being piezoelectric ceramic-, used to convert impact mechanical energy into charge signals; The amplifier circuit (3) includes a four-channel operational amplifier U3, a charge amplifier and a voltage amplifier. The four-channel operational amplifier U3 is divided into four independent operational amplifiers: operational amplifier U3A, operational amplifier U3B, operational amplifier U3C and operational amplifier U3D, which are used to convert the charge signal into a voltage signal and perform differential amplification. The reference voltage circuit (4) includes a voltage reference source chip U2, which is used to provide a high-precision DC bias voltage. The filter circuit (5) includes a resistor R8 and a capacitor C9, which are used to filter out high-frequency noise in the amplified signal. The output drive circuit (6) is composed of an operational amplifier U3D, which is used to reduce the output impedance and improve the load capacity. Each module is electrically connected by wires.

2. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The bidirectional transient suppression diode TVS1 is connected in parallel between the positive terminal VCC and the negative terminal GND of the external power supply. The Schottky diode D1 is connected in series between the positive terminal VCC and the power filter unit. The output terminal of the power filter unit is connected to the input terminal of the low dropout linear regulator U1. The output terminal of the low dropout linear regulator U1 outputs the supply voltage VDD.

3. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The charge amplifier consists of operational amplifier U3A, capacitor C13, resistor R9, operational amplifier U3B, capacitor C14, resistor R10. The output of operational amplifier U3A is fed back to its inverting input through capacitor C13, and resistor R9 is connected in parallel across capacitor C13. The output of operational amplifier U3B is fed back to its inverting input through capacitor C14, and resistor R10 is connected in parallel across capacitor C14.

4. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The voltage amplifier consists of operational amplifier U3C, resistors R2-R7, and capacitors C7 and C8. Resistor R2 is connected in series between the inverting input and output of operational amplifier U3C; resistor R3 is connected in parallel between the inverting input of operational amplifier U3C and the negative terminal of the external power supply GND; resistor R4 is connected in series between the non-inverting input of operational amplifier U3C and the reference voltage VREF; resistor R5 is connected in parallel between the non-inverting input of operational amplifier U3C and the negative terminal of the external power supply GND; resistor R6 is connected in series between the output of operational amplifier U3A and the negative terminal of the external power supply GND; and resistor R7 is connected in series between the output of operational amplifier U3B and the negative terminal of the external power supply GND.

5. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The voltage reference source chip U2 of the reference voltage circuit (4) has a decoupling capacitor C5 connected in parallel at its input terminal and a bypass capacitor C6 connected in parallel at its output terminal.

6. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The resistor R8 and capacitor C9 of the filter circuit (5) constitute a low-pass filter unit.

7. The circuit based on a piezoelectric impact sensor according to claim 1, characterized in that, The operational amplifier U3D of the output drive circuit (6) forms a voltage follower.

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