Piezoelectric ceramic sensor signal conditioning circuit

Abstract

The utility model relates to a piezoelectric ceramic sensor signal conditioning circuit, which comprises an input end, a filtering module, a field effect transistor, a voltage reference chip and an output end, and is characterized in that the input end is provided with an input interface for receiving input signals; the filtering module is connected with the input interface; a grid electrode of the field-effect tube is connected with the filtering module, a source electrode of the field-effect tube is connected with the constant current source, and a drain electrode of the field-effect tube is grounded; a reference voltage port of the voltage reference chip is connected with a source electrode of the field effect transistor; the output end is provided with an I EPE interface used for outputting signals. According to the utility model, fewer components with smaller packaging sizes are adopted, and the conversion of a sensor circuit for converting a charge signal output by the piezoelectric ceramic into a voltage signal and outputting the voltage signal through a standard I EPE interface is realized, so that the sensor can be directly connected with a signal acquisition system for use.

Description

Technical Field

[0001] The utility model relates to the technical field of piezoelectric ceramic sensor signal processing, in particular to a piezoelectric ceramic sensor signal conditioning circuit. Background Art

[0002] At present, piezoelectric ceramic sensors used to measure vibration, shock and acceleration usually need to be directly mounted on the measured object. However, the volume and weight of some of the measured objects are not all far beyond the volume and weight of the sensor. Therefore, when selecting sensors, the sensors are required to be as small and miniaturized as possible in order to minimize the impact of the installation of the sensors on the characteristics of the measured objects. It can be seen that when designing sensors, the sensors need to be miniaturized and miniaturized as much as possible.

[0003] The sensor uses piezoelectric ceramics as the measuring sensitive device. When the sensor is working, the piezoelectric ceramics will generate a charge signal. Since this charge signal is very weak, a signal conditioning circuit is needed to process the charge signal generated by the piezoelectric ceramics. The signal conditioning circuit is a key part of the sensor, but the signal conditioning circuit in the prior art has the defects of more circuit components, complex circuit structure, larger package size and high cost, which seriously limits the development of miniaturization and micro-miniaturization of sensors, and the signal processed by the signal conditioning circuit in the prior art is not easy to be directly collected and used by the signal acquisition system.

[0004] Therefore, there is an urgent need to propose an innovative piezoelectric ceramic sensor signal conditioning circuit to overcome the above-mentioned technical defects in the prior art. Utility Model Content

[0005] To this end, the technical problem to be solved by the utility model is to overcome the technical defects existing in the prior art, and propose a piezoelectric ceramic sensor signal conditioning circuit, which uses fewer components with smaller packaging size, realizes the conversion of the sensor circuit that converts the piezoelectric ceramic output charge signal into a voltage signal and outputs it with a standard IEPE interface, making it convenient for the sensor to be directly connected to the signal acquisition system for use.

[0006] In order to solve the above technical problems, the utility model provides a piezoelectric ceramic sensor signal conditioning circuit, comprising:

[0007] An input terminal having an input interface for receiving an input signal;

[0008] A filter module connected to the input interface;

[0009] A field effect tube, a gate of which is connected to the filter module, a source of which is connected to a constant current source, and a drain of which is grounded;

[0010] A voltage reference chip, whose reference voltage port is connected to the source of the field effect tube;

[0011] An output end having an IEPE interface for outputting signals.

[0012] In one embodiment of the present invention, a first resistor is further included, and the first resistor is connected between the source of the field effect tube and the constant current source.

[0013] In one embodiment of the present invention, a first capacitor is further included, and the first capacitor is connected between the positive electrode and the negative electrode of the IEPE interface.

[0014] In one embodiment of the present invention, the input interface includes a positive connection point and a negative connection point, the positive connection point is connected to the filter module, and the negative connection point is grounded.

[0015] In one embodiment of the utility model, the filtering module includes a second resistor, a third resistor, a second capacitor and a third capacitor, the third resistor, the second capacitor and the third capacitor are all connected in parallel between the positive connection point and the negative connection point, and the second resistor is connected between the second capacitor and the positive connection point.

[0016] In one embodiment of the present invention, a fourth resistor is further included, and the fourth resistor is connected to the drain of the field effect tube.

[0017] In one embodiment of the present utility model, the power port of the voltage reference chip is connected to the constant current source, and the ground port of the voltage reference chip is grounded.

[0018] The above technical solution of the utility model has the following advantages compared with the prior art:

[0019] 1. The signal conditioning circuit of the utility model adopts fewer components with smaller package size, realizes the conversion of the sensor circuit that converts the charge signal output by piezoelectric ceramics into a voltage signal and outputs it through a standard IEPE interface, which is convenient for the sensor to be directly connected to the signal acquisition system;

[0020] 2. The utility model provides a circuit solution for realizing the standardization of the signal conditioning interface of piezoelectric ceramic sensors using discrete devices. The field effect tubes and voltage reference chips used are basic electronic components with low cost and easy to purchase. The remaining circuit components are only resistors and capacitors. All electronic components are highly replaceable and are not limited to a certain model of products from a certain manufacturer. Instead, they can be used as long as the corresponding parameters are met. All electronic components in this design have a variety of different package sizes. Therefore, the appropriate component package can be selected according to the design size of the sensor to meet the installation size requirements of the signal conditioning circuit for piezoelectric sensors of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments of the utility model in combination with the accompanying drawings.

[0022] Figure 1 It is a schematic diagram of a piezoelectric ceramic sensor signal conditioning circuit proposed in an embodiment of the utility model. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0024] Reference Figure 1 As shown, an embodiment of the utility model provides a piezoelectric ceramic sensor signal conditioning circuit, including an input end, a filtering module, a field effect tube U2, a voltage reference chip U1 and an output end, wherein the input end has an input interface for receiving an input signal; the filtering module is connected to the input interface; the gate of the field effect tube U2 is connected to the filtering module, the source of the field effect tube U2 is connected to a constant current source, and the drain of the field effect tube U2 is grounded; the reference voltage port of the voltage reference chip U1 is connected to the source of the field effect tube U2; and the output end has an IEPE interface for outputting a signal.

[0025] The signal conditioning circuit of the utility model adopts fewer components with smaller package size, realizes the conversion of the sensor circuit of converting the charge signal output by the piezoelectric ceramic into a voltage signal and outputting it with a standard IEPE interface, and is convenient for the sensor to be directly connected to the signal acquisition system for use.

[0026] The piezoelectric ceramic sensor signal conditioning circuit proposed in this embodiment can easily convert the charge signal generated by the piezoelectric ceramic of the piezoelectric sensor into a voltage signal and output it in a standard IEC 60444 interface. Figure 1As shown, the input interface of the signal conditioning circuit of this embodiment is connected to the piezoelectric ceramic output electrode of the sensor. After the charge signal enters the circuit, it is filtered by the filtering module, and the signal conditioning amplification and conversion of the charge signal to a voltage signal are realized through the field effect transistor U2 and the voltage reference chip U1 of the circuit, and then output through the IEPE interface.

[0027] Wherein, the input interface includes a positive connection point T1+ and a negative connection point T1-, the positive connection point T1+ is connected to a filter module, the negative connection point T1- is grounded, the filter module includes a second resistor R2, a third resistor R3, a second capacitor C2 and a third capacitor C3, the third resistor R3, the second capacitor C2 and the third capacitor C3 are all connected in parallel between the positive connection point T1+ and the negative connection point T1-, the second resistor R2 is connected between the second capacitor C2 and the positive connection point T1+, the power port of the voltage reference chip U1 is connected to a constant current source, and the ground port of the voltage reference chip U1 is grounded. During specific operation, the positive connection point T1+ and the negative connection point T1- of the signal conditioning circuit of this embodiment are connected to the piezoelectric ceramic output electrode of the sensor, and after the charge signal enters the circuit, it is filtered by the filter module composed of components such as the resistor and capacitor of the circuit, and the signal conditioning amplification and the conversion of the charge signal to the voltage signal are realized through the field effect tube U2 of the circuit and the voltage reference chip U1, and then the output is connected through the I EPE interface of H1 and H2.

[0028] The piezoelectric ceramic sensor signal conditioning circuit provided in this embodiment also includes a first resistor R1, a first capacitor C1 and a fourth resistor R4, the first resistor R1 is connected between the source of the field effect tube U2 and the constant current source, the first capacitor C1 is connected between the positive electrode I EPE+ and the negative electrode I EPE- of the I EPE interface, and the fourth resistor R4 is connected to the drain of the field effect tube U2. In this embodiment, the positive connection point T1+ and the negative connection point T1- are used to connect the positive and negative electrodes of the piezoelectric ceramic, and H1 and H2 are the sensor I EPE output / input interface, H1 accesses the constant current provided by the signal acquisition device, usually 2-10mA constant current (when the constant current source is not connected to the sensor load, the output is generally 24V / 2-10mA, usually 24V / 4mA), and the sensor output signal is loaded on this constant current power supply and output in voltage form. After the constant current source enters the sensor, a reference voltage is generally set, which is called the zero point voltage in the sensor. In order to maximize the voltage amplitude range of the sensor output signal, the zero point voltage of the sensor is generally set to about half of the constant current source voltage amplitude provided by the acquisition device ( For example, if the constant current source is a 24V power supply, the zero voltage of the sensor is generally set at about 12V. Considering the fluctuation of the constant current source voltage of the acquisition equipment and the output amplitude range of the sensor, the zero voltage of the sensor is generally set between 8-15V). In the circuit of this embodiment, the first resistor R1 is used to set the zero voltage of the sensor, the second resistor R2 is used to adjust the flatness of the sensitivity curve of the high-frequency band of the sensor output, the third resistor R3 is used to adjust the flatness of the sensitivity curve of the low-frequency band of the sensor output, and the fourth resistor R4 is used to assist in adjusting the output sensitivity and zero voltage of the sensor. The first capacitor C1 is mainly used for power supply filtering on the IEPE interface. If the installation space of the sensor signal conditioning circuit board is relatively limited, the first capacitor C1 can be cancelled, and the second capacitor C2 and the third capacitor C3 are used to adjust the sensitivity of the sensor output. In addition, the second resistor R2, the second capacitor C2 and the third capacitor C3 also have the function of low-pass filtering. This part of the low-pass filtering circuit can be used to compensate for the high-frequency end of the amplitude-frequency response curve of the output signal caused by the resonance of the piezoelectric ceramic.

[0029] The utility model provides a circuit scheme for realizing standardization of the signal conditioning interface of a piezoelectric ceramic sensor using discrete devices. The field effect transistor U2 and the voltage reference chip U1 used are both basic electronic components with low cost and easy to purchase. The remaining circuit components are only resistors and capacitors. All electronic components are highly replaceable and are not limited to a certain model of products from a certain manufacturer. Instead, they can be used as long as the corresponding parameters are met. Moreover, all electronic components in the design scheme have a variety of different package sizes. Therefore, a suitable component package can be selected according to the design size of the sensor to meet the installation size requirements of the signal conditioning circuit for piezoelectric sensors of different sizes.

[0030] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention of the utility model.

Claims

1. A piezoelectric ceramic sensor signal conditioning circuit, characterized in that: include: An input terminal having an input interface for receiving an input signal; A filtering module connected to the input interface; A field effect tube, a gate of which is connected to the filter module, a source of which is connected to a constant current source, and a drain of which is grounded; A voltage reference chip, whose reference voltage port is connected to the source of the field effect tube; An output end having an IEPE interface for outputting signals.

2. The piezoelectric ceramic sensor signal conditioning circuit according to claim 1, characterized in that: It also includes a first resistor, which is connected between the source of the field effect tube and the constant current source.

3. A piezoelectric ceramic sensor signal conditioning circuit according to claim 1 or 2, characterized in that: It also includes a first capacitor, which is connected between the positive electrode and the negative electrode of the IEPE interface.

4. A piezoelectric ceramic sensor signal conditioning circuit according to claim 1 or 2, characterized in that: The input interface includes a positive connection point and a negative connection point, the positive connection point is connected to the filter module, and the negative connection point is grounded.

5. The piezoelectric ceramic sensor signal conditioning circuit according to claim 4, characterized in that: The filtering module includes a second resistor, a third resistor, a second capacitor and a third capacitor, the third resistor, the second capacitor and the third capacitor are all connected in parallel between the positive connection point and the negative connection point, and the second resistor is connected between the second capacitor and the positive connection point.

6. The piezoelectric ceramic sensor signal conditioning circuit according to claim 4, characterized in that: It also includes a fourth resistor, which is connected to the drain of the field effect tube.

7. The piezoelectric ceramic sensor signal conditioning circuit according to claim 1, characterized in that: The power port of the voltage reference chip is connected to the constant current source, and the ground port of the voltage reference chip is grounded.

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