A microprobe-based non-contact electrostatic potential tester

Abstract

The application belongs to the technical field of electrostatic measurement, and particularly relates to a non-contact electrostatic potential tester based on a micro probe. The non-contact electrostatic potential tester comprises a shielding shell, an induction electrode, a conductor plate, a conductor filament, a test module and an insulating medium. The shielding shell is a columnar structure with two open ends. The two ends of the shielding shell are respectively provided with the insulating medium. The induction electrode is fixed to the insulating medium at one end of the shielding shell. The test module and the conductor plate are respectively fixed to the insulating medium at the other end of the shielding shell. The test module is provided with a test electrode. The conductor filament is located in the shielding shell and is respectively connected to the induction electrode and the conductor plate at two ends. The insulating medium is arranged on the two sides of the conductor filament. The insulating medium is arranged between the conductor plate and the test module.

Description

Technical Field

[0001] This invention belongs to the field of electrostatic measurement technology, specifically relating to a non-contact electrostatic potential tester based on a microprobe. Background Technology

[0002] Static electricity, as a potential or direct hazard, widely affects people's lives and production, and is particularly important in fields such as petrochemicals, aerospace, and pyrotechnics. Electrostatic potential testing is a crucial step in electrostatic early warning and protection. Currently, electrostatic potential testers are mainly divided into two types: contact and non-contact. Both can be used for conductor potential testing. However, when it is necessary to avoid electrical contact with charged bodies or to test the potential of insulators, only non-contact electrostatic potential testers can be used.

[0003] Common non-contact electrostatic potential testers can be categorized into vibration capacitance type, rotating blade type, current collector type, and MEMS type, depending on their measurement principles. Their working principle involves the probe approaching a charged object without direct contact, causing a distortion in the electric field generated by the charge on the object. The tester measures the electric field strength at the probe's location after this distortion, and then obtains the potential value of the charged object through calibration.

[0004] The shortcomings of existing technologies and the technical problems to be solved by this invention:

[0005] Large probe size leads to large measurement error: Most non-contact electrostatic potential testers have relatively large probes, which can significantly affect the electrostatic state of charged objects when measured close to them. Even with on-site calibration and elimination of environmental influences, the measurement results may still have large errors and uncertainties.

[0006] The contradiction between sensitivity and detection area: While increasing the measurement distance can reduce the influence of the probe on the charged body, it will reduce the sensitivity and increase the detection area, resulting in the measurement result being the average effect of the charge distribution in the detection "field of view".

[0007] Poor comparability of measurement results: Different probe sizes have different effects on the electrostatic state of charged bodies, resulting in large differences in the measurement results of the same charged body using different probes, poor comparability, and almost none of them can accurately measure the electrostatic potential of small-sized or small-capacitance charged bodies. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a non-contact electrostatic potential tester based on a microprobe. The aim is to reduce the influence on the electrostatic state of charged bodies by decreasing the probe size, thereby achieving high-precision measurement of electrostatic potential and testing the electrostatic potential of small-sized or small-capacitance charged bodies. Simultaneously, by shielding the signal influence from areas outside the detection zone, it enables the measurement of the localized potential of a micro-region on the surface of the charged body.

[0009] The technical solution for implementing the present invention is as follows: In a first aspect, the present invention provides a non-contact electrostatic potential tester based on a microprobe, comprising: a shielding shell, a sensing electrode, a conductor plate, a conductor filament, a test module, and an insulating medium; wherein, the shielding shell is a columnar structure with openings at both ends, and insulating media are respectively disposed at both ends of the shielding shell; the sensing electrode is fixed on the insulating medium at one end of the shielding shell; the test module and the conductor plate are respectively fixed on the insulating medium at the other end of the shielding shell; the test module is provided with a test electrode; the conductor filament is located inside the shielding shell, and its two ends are respectively connected to the sensing electrode and the conductor plate; insulating media are disposed on both sides of the conductor filament, and an insulating medium is disposed between the conductor plate and the test module.

[0010] Optionally, the shielding shell of the present invention has an extended and adjustable structure at one end of the sensing electrode.

[0011] Optionally, the shielding shell of the present invention is made of a subconductor material.

[0012] Optionally, the present invention determines the sensitivity of the sensor test module by adjusting the size of the coupling capacitance formed between the conductor plate and the electrode plate of the test module. The adjustment method is: (1) adjusting the insulating medium between the conductor plate and the electrode plate of the test module, or (2) setting a capacitor between the conductor plate and the electrode plate and adjusting the size of the set capacitor.

[0013] Optionally, the sensing electrode of the present invention is a flat conductor electrode, a conductor ball electrode, or a conductor hemispherical electrode.

[0014] Optionally, the signal testing circuit in the test module of the present invention includes: a signal acquisition circuit, a post-amplifier circuit, a DC biaser, an active low-pass filter, and a voltage follower.

[0015] Optionally, the signal acquisition circuit of the present invention includes a direct sensing signal acquisition circuit and an AC modulation signal acquisition circuit. The test circuit further includes a switching circuit. When performing low-to-high frequency signal testing, the switching circuit controls the direct sensing signal acquisition circuit to work. When performing low-frequency signal testing, the switching circuit controls the AC modulation signal acquisition circuit to work.

[0016] Optionally, the direct sensing signal acquisition circuit of the present invention includes an operational amplifier. ,capacitance , and ,switch and Among them, capacitor Connected to the electrode plate and operational amplifier Between the inverting input terminals, the capacitor and Parallel to operational amplifier Between the output terminal and the inverting input terminal, the switch Set in capacitor On the branch, operational amplifier The inverting input is connected to a switch. Ground, operational amplifier The positive input terminal is grounded.

[0017] Optionally, the AC modulation signal acquisition circuit of the present invention includes: a ground electrode, an operational amplifier, a resistor, and a capacitor; wherein, the ground electrode is a circular electrode with a hole; the electrode plate is connected to the inverting input terminal of the operational amplifier, the connecting wire passes through the circular hole on the ground electrode, the resistor and capacitor are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier, and the ground electrode and the non-inverting input terminal of the operational amplifier are grounded.

[0018] Optionally, the tester of the present invention further includes an analog-to-digital converter, a microcontroller unit, a direct digital frequency synthesizer, and a vibration structure; When performing low- to high-frequency signal testing, the voltage signal processed by the test module is acquired at high speed by an analog-to-digital converter and then entered into the microcontroller unit for calibration to calculate the potential value of the charged body. When performing low-frequency signal testing, the AC signal output by the direct digital frequency synthesizer controlled by the microcontroller directly drives the vibrating structure, causing the grounding electrode, which is rigidly connected to the vibrating structure, to vibrate periodically. Subsequently, after I / V conversion and subsequent processing, the signal is output to the analog-to-digital converter. The microcontroller also needs to perform amplitude signal processing on the voltage signal, and the amplitude is proportional to the magnitude of the electric field on the surface of the charged body being tested, so as to calculate the potential value of the charged body.

[0019] Beneficial effects: Microprobe reduces measurement interference: In the prior art, the probe size is large, which has a significant impact on the electrostatic state of charged bodies. This invention reduces the probe size to the mm level, which significantly reduces the impact of the probe on the electrostatic state of charged bodies and fundamentally solves the problem of large measurement errors caused by the large probe size.

[0020] Micro-area measurement using shielded enclosure: A design of an extended and adjustable subconductor shielded enclosure is proposed. By adjusting the shielding depth and test distance, the test area can be flexibly controlled, enabling potential measurement from micro-areas on the order of mm² to wider areas on the order of cm². This achieves accurate measurement of electrostatic potential of small charged bodies and local potential measurement of micro-areas.

[0021] Adaptive design of sensing electrodes: Different shapes of sensing electrodes, such as flat plates and hemispherical electrodes, are designed according to the different shapes of the tested area of ​​the charged body, so that the tester can better adapt to different test scenarios and improve the accuracy and applicability of the measurement.

[0022] Signal processing optimization: For the frequency range of the measured signal from DC to low frequency and from low frequency to high frequency, both direct induction and AC modulation signal processing methods are provided, which improves signal quality and measurement accuracy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a structural diagram of the microprobe; Figure 2 This is an equivalent diagram of the principle of non-contact electrostatic potential testing. Figure 3 This is an equivalent diagram of the microprobe testing principle of the present invention; Figure 4 Induction electrodes of different shapes: (a) flat plate electrode, (b) hemispherical electrode; Figure 5 A cross-sectional view of the extended subconductor shielding shell; Figure 6 This is the signal processing circuit diagram for the test module; Figure 7 For the signal processing circuit of the test module—direct sensing; Figure 8 The signal processing circuit for the test module is AC modulation, (a) signal amplification circuit, and (b) vibration structure. Figure 9 This is a test flowchart. Detailed Implementation

[0025] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0027] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0028] like Figure 1 As shown in the figure, an embodiment of this application discloses a non-contact electrostatic potential tester based on a microprobe, comprising: a shielding shell, a sensing electrode, a conductor plate, a conductor filament, a test module, and an insulating medium; wherein, the shielding shell is a columnar structure with openings at both ends, and insulating media are respectively disposed at both ends of the shielding shell; the sensing electrode is fixed on the insulating media at one end of the shielding shell, and the test module and the conductor plate are respectively fixed on the insulating media at the other end of the shielding shell; the test module is provided with a test electrode; the conductor filament is located inside the shielding shell, and its two ends are respectively connected to the sensing electrode and the conductor plate; insulating media are disposed on both sides of the conductor filament, and an insulating medium is disposed between the conductor plate and the test module.

[0029] In this embodiment, the front end of the test microprobe is a sensing electrode, which is electrically connected to the larger conductor plate at the rear end via a conductor filament. The probe's subconductor shielding shell is made of a subconductor material, which shields against external environmental interference through grounding and is insulated from the test pieces of various conductor materials through insulating medium 1. The conductor filament and the subconductor shielding shell together form a distributed capacitance through insulating medium 2, creating a channel for transmitting charge signals between the front sensing electrode and the rear conductor plate. The rear conductor plate is isolated from the test electrodes on the test module through insulating medium 3, and the two form a coupling capacitance, becoming the main bridge for voltage signal transmission.

[0030] Figure 2 This is an equivalent diagram of the principle of non-contact electrostatic potential testing in the prior art, where each capacitor is defined as follows: The initial capacitance to ground of a charged body; : Coupling capacitance between the sensor's sensing electrode and the charged body; : Coupling capacitance between the sensor grounding housing and the charged body; Stray capacitance to ground in sensor signal transmission; : The capacitance to ground of the sensor test module.

[0031] When the initial surface voltage of the charged body is At that time, the surface charge is Therefore, when the probe approaches the test, the electrostatic state of the charged body changes, and at this time, its capacitance to ground is... (1) in, Let be the initial capacitance to ground of the charged body. This refers to the coupling capacitance between the sensor's grounded housing and the charged component. This is the series connection between the coupling capacitance of the sensor's sensing electrode and the charged body and the sensor's own input capacitance. Correspondingly, the surface voltage of the charged body is: (2) Therefore, the actual measured voltage value is less than the initial surface voltage of the charged body. Generally, Therefore, it is mainly due to and This affects the electrostatic state of the charged body, causing measurement deviations.

[0032] Figure 3 The equivalent diagram is shown below, based on the principle of non-contact electrostatic potential testing using a microprobe. The capacitances are defined as follows: : The capacitance of a charged body to ground; : Coupling capacitance between the sensor's sensing electrode and the charged body; : Coupling capacitance between the sensor grounding housing and the charged body; Stray capacitance to ground in sensor signal transmission includes the capacitance to ground of the sensing electrodes, conductive filaments, and conductor plates. : Coupling capacitance between the sensor conductor plate and the signal input terminal of the test module; : The capacitance to ground at the signal input terminal of the sensor test module.

[0033] according to Figure 1 The probe structure, by extending the test probe and reducing its cross-sectional size, reduces the influence of the testing instrument itself on the electrostatic state of the charged body, that is, reduces the coupling capacitance between the sensor's sensing electrode and the charged body. and the coupling capacitance between the sensor grounding housing and the charged body .

[0034] By adjusting the coupling capacitor The size of the sensor test module is used to determine its sensitivity, and to reduce the increased stray capacitance to ground caused by the extended test probe. The effect of adjusting the coupling capacitor The methods are: (1) adjusting the insulating medium 3 between the conductor plate and the electrode plate of the test module, or (2) adjusting the actual capacitance between the two by means of electrical connection. Both methods can achieve coupling capacitance. Adjustments to the coupling capacitor are necessary when electrostatic discharge is likely to occur under near-field, high-voltage testing conditions. It can effectively isolate the test module from charged bodies, reduce the potential electrostatic damage to the test module, and reduce the influence of the test module's own parameters on the test signal during transmission.

[0035] Furthermore, such as Figure 4 The sensing electrode shown is designed as follows: Figure 4 This image shows a cross-sectional view of a microprobe used in testing instruments for different applications. If the test area of ​​the charged body is relatively flat and its surface electric field is approximately uniform, then a flat conductor electrode is used as the induction electrode, such as... Figure 4 As shown in (a); if the test area of ​​the charged body has various different shapes, the shape of the induction electrode is a conducting sphere or a conducting hemisphere, and the electric field in each direction on the surface of the charged body is tested equivalently, such as... Figure 4 As shown in (b).

[0036] Furthermore, such as Figure 5 The shielding enclosure design shown is as follows: Figure 5 To extend the cross-sectional structure of the adjustable subconductor shielding shell, and based on the requirements of the actual testing scenario, extending the length of the subconductor shielding shell can shield the electric field interference in areas other than the local surface area of ​​the charged object under test, thus reducing the test area area during close-range testing. The test area A is closely related to the shielding depth D and the test distance L. If the probe cross-sectional size is selected to be on the order of mm, adjusting the shielding depth to a deeper level and reducing the test distance can approximately achieve a micro-area area (mm²). 2 Average potential testing (on the order of magnitude); when the shielding depth is shallow, appropriately increasing the testing distance can approximate a wider area (cm). 2 Evaluation of surface potential (on the order of magnitude).

[0037] In addition, the subconductor shielding shell is made of subconductor material. When conducting micro-area testing, if the electric field on the surface of the charged body is strong enough to cause electrostatic discharge, the extended subconductor shielding shell can effectively limit the magnitude of the discharge current released onto the subconductor shielding shell, further reducing the possibility of electrostatic discharge damaging the tester.

[0038] Furthermore, such as Figure 6 The direct induction signal test and processing circuit shown is as follows: Figure 6 The signal processing circuit of the test module can be divided into five parts. This is a signal acquisition circuit, in which, Figure 6 The electrode plate shown is Figure 1 The conductor plate in the microprobe structure diagram constitutes a coupling capacitor. The test signal passes through the coupling capacitor. This signal is then transmitted to subsequent acquisition and processing. For direct induction testing, it can be used to acquire broadband electric field signals from low to high frequencies, primarily relying on the bandwidth of the operational amplifier and analog-to-digital converter. Generally, it can process signals up to kHz or even higher frequencies. When the electric field on the surface of a charged object is a low-frequency field, the input resistance of the testing instrument must be high enough to slow down the attenuation of the test signal; therefore, the operational amplifier... A voltage follower with unity-gain amplification is used, and the leakage current at the input of the operational amplifier is further reduced by adding a guard ring; [Selection] , The bootstrap circuit and resistor R2 are used to compensate for the operational amplifier bias current to prevent operational amplifier saturation. For the subsequent amplifier circuit, the resistance values ​​and ratios of high-precision resistors are set to achieve preliminary signal processing. The amplification factor is... . It is an active low-pass filter, which is configured by setting... , , , The value of is used to determine the cutoff frequency and filter out high-frequency interference signals. To apply a DC bias voltage to the signal, through a resistor , For reference voltage Perform a resistor voltage divider, then pass it through a voltage follower. The high input impedance and low output impedance characteristics reduce resistance. , This affects the test signal. In-phase adder. The DC bias voltage after resistor voltage division and The filtered test signals are superimposed. It is a voltage follower. Used as a voltage follower, its low output impedance reduces signal attenuation during subsequent test signal acquisition.

[0039] Figure 6 The signal processing circuit of the test module Some signal acquisition circuits can be implemented using other testing methods. For example... Figure 7 This is a signal acquisition circuit based on the charge amplifier principle. Figure 7 The electrode plate shown is Figure 1 The conductor plate in the microprobe structure diagram constitutes a coupling capacitor. Operational amplifier The positive input terminal is connected to the ground electrode, while the reverse input terminal remains at a "virtual ground" zero potential. During the measurement, surface charge is generated on the surface of the sensing electrode of the microprobe. Due to electrostatic equilibrium, the test signal passes through the conductor filament and capacitor. Transmitted to capacitor (and needs to meet) Much larger ),So, The output voltage is By controlling the closing of the switch , with capacitor Larger capacitors in parallel To accommodate larger range settings, at this time The output voltage is Although a high-precision operational amplifier with an input bias current on the order of several fA is selected, and signal calibration can be performed on the test signal, prolonged testing may cause the operational amplifier to saturate. This can be addressed by controlling the closed switch. , Capacitors and The accumulated charge is released to the ground.

[0040] Furthermore, such as Figure 8 The AC modulation signal test and processing circuit shown is as follows: Figure 6 The signal acquisition circuit in section P1 of the signal processing circuit of the test module can be further adopted... Figure 8 The test method for AC modulation is shown. Generally, AC modulation methods are limited by the frequency of the modulating signal and are mainly suitable for measuring low-frequency electric field signals (0Hz to several hundred Hz). Figure 8 The electrode plate shown in (a) and Figure 1 The conductor plate in the microprobe structure diagram constitutes a coupling capacitor. The electrode plate and the subsequent ground electrode together form the ground capacitance of the sensor test module. . Figure 8 (b) is a micro-vibration structure modulated by AC, with a perforated circular electrode serving as the grounding electrode for periodic vibration. It vibrates periodically with a sinusoidal signal through the ground plane, and the induced current on the electrode plate is... ,in, Let be the potential of the electrode plate, and k be the amplitude of the ground plane vibration. This is the angular frequency of the sinusoidal signal. Subsequently, because the magnitude of the induced signal is very weak, it is converted into a easily processed voltage signal by an I / V conversion module, and then... Figure 6 The circuitry following P1 performs signal processing.

[0041] Other common AC modulation methods include rotary blade sensors and MEMS sensors.

[0042] The voltage signal from the direct sensing test module mentioned above, after being amplified, filtered, and DC biased, is acquired at high speed by an analog-to-digital converter and then enters the microcontroller unit. The signal is displayed on the screen and transmitted via external communication.

[0043] For the AC modulation test module, the test signal characteristics depend on the parameters of the periodically driven signal. First, the AC signal output by the direct digital frequency synthesizer controlled by the microcontroller directly drives the vibrating structure, causing the ground electrode, which is rigidly connected to the vibrating structure, to vibrate periodically. Subsequently, after I / V conversion and subsequent processing, the signal is output to the analog-to-digital converter. The microcontroller also needs to perform amplitude signal processing on the voltage signal, and the amplitude is proportional to the magnitude of the electric field on the surface of the charged body under test.

[0044] Furthermore, such as Figure 9 The test flow diagram shown is as follows: The test flow diagram of the non-contact electrostatic potential tester based on a microprobe is shown below. Figure 9 As shown. First, when the induction electrode (plate electrode or hemispherical electrode) is close to the charged body, based on the principle of electrostatic induction, the electric field generated in space by the surface charge of the charged body induces a charge on the induction electrode. If the area to be measured is a flat surface with a uniform electric field, the plate electrode is parallel to the surface of the charged body, and the induced charge is evenly distributed. If the area to be measured has a complex shape, the hemispherical electrode can equivalently induce electric fields in all directions, ensuring that the induced signal can accurately reflect the surface potential of the charged body. The induced charge signal generated by the induction electrode is transmitted to the rear conductor plate through a conductor filament. A distributed capacitance is formed between the conductor filament and the subconductor shielding shell. This distributed capacitance serves as a channel for charge signal transmission and simultaneously ensures electrical isolation during signal transmission, avoiding external interference.

[0045] The back-end conductor plate and the test electrodes on the test module form a coupling capacitor. The charge signal transmitted to the conductor plate is converted into a voltage signal through this coupling capacitor, realizing the initial conversion from charge signal to voltage signal and providing a foundation for subsequent signal processing.

[0046] Based on the testing requirements of DC-low frequency field and low-frequency-high frequency field, DC induction testing or AC modulation testing is selected. The processed voltage signal is acquired at high speed through an analog-to-digital converter (ADC), with the sampling rate determined according to the signal frequency. For direct induction test signals, the microcontroller unit performs calibration and other processing on the acquired voltage signal to calculate the potential value of the charged body. For AC modulation test signals, the microcontroller unit performs amplitude analysis on the voltage signal. Since the amplitude is proportional to the electric field strength on the surface of the charged body under test, it can be converted into the corresponding potential value through calibration.

[0047] The processed potential value is displayed in real time on an LCD screen or transmitted to a PC terminal for graphical display, making it easy for operators to intuitively obtain the measurement results.

[0048] Communication module: Outputs data via communication interfaces such as USB, Bluetooth, and RS485, supporting remote monitoring and data storage to meet the needs of industrial sites and other scenarios.

[0049] Existing non-contact electrostatic potential testers mainly suffer from problems such as large probe size, large measurement error, and inability to accurately measure small charged bodies. However, this invention effectively solves these problems through innovative designs such as micro probes, shielded shells, adaptive sensing electrodes, and optimized signal processing circuits. It is superior to existing technologies in terms of measurement accuracy, applicability, and anti-interference ability.

[0050] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A non-contact electrostatic potential tester based on a microprobe, characterized in that, include: The system comprises a shielding shell, a sensing electrode, a conductor plate, a conductor filament, a test module, and an insulating medium. The shielding shell is a columnar structure open at both ends, with insulating media at each end. The sensing electrode is fixed to the insulating media at one end of the shielding shell, and the test module and conductor plate are fixed to the insulating media at the other end of the shielding shell. The test module has an electrode plate. The conductor filament is located inside the shielding shell, with its two ends connected to the sensing electrode and the conductor plate, respectively. Insulating media are provided on both sides of the conductor filament, and an insulating medium is provided between the conductor plate and the test module. The shielding shell is provided with an extended adjustable structure at one end of the sensing electrode; the shielding shell is made of a subconductor material; the sensitivity of the sensor test module is determined by adjusting the size of the coupling capacitance formed between the conductor plate and the electrode plate of the test module. The adjustment method is: (1) adjusting the insulating medium between the conductor plate and the electrode plate of the test module, or (2) setting a capacitor between the conductor plate and the electrode plate and adjusting the size of the set capacitor; to realize potential measurement from a micro-area on the mm² scale to a wider area on the cm² scale.

2. The non-contact electrostatic potential tester based on a microprobe according to claim 1, characterized in that, The sensing electrode is a flat conductor electrode, a conductor ball electrode, or a conductor hemispherical electrode.

3. The non-contact electrostatic potential tester based on a microprobe according to claim 1, characterized in that, The signal testing circuit in the test module includes: a signal acquisition circuit, a post-amplifier circuit, a DC bias circuit, an active low-pass filter, and a voltage follower.

4. The non-contact electrostatic potential tester based on a microprobe according to claim 3, characterized in that, The signal acquisition circuit includes a direct sensing signal acquisition circuit and an AC modulation signal acquisition circuit. The test circuit also includes a switching circuit. When performing low-to-high frequency signal testing, the switching circuit controls the direct sensing signal acquisition circuit to work. When performing low-frequency signal testing, the switching circuit controls the AC modulation signal acquisition circuit to work.

5. The non-contact electrostatic potential tester based on a microprobe according to claim 4, characterized in that, The direct sensing signal acquisition circuit includes an operational amplifier. ,capacitance , and ,switch and Among them, capacitor Connected to the electrode plate and operational amplifier Between the inverting input terminals, the capacitor and Parallel to operational amplifier Between the output terminal and the inverting input terminal, the switch Set in capacitor On the branch, operational amplifier The inverting input is connected to a switch. Ground, operational amplifier The positive input terminal is grounded.

6. The non-contact electrostatic potential tester based on a microprobe according to claim 4, characterized in that, The AC modulation signal acquisition circuit includes: a ground electrode, an operational amplifier, a resistor, and a capacitor; wherein, the ground electrode is a circular electrode with a hole; the electrode plate is connected to the inverting input terminal of the operational amplifier, the connecting wire passes through the circular hole on the ground electrode, the resistor and capacitor are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier, and the ground electrode and the non-inverting input terminal of the operational amplifier are grounded.

7. The non-contact electrostatic potential tester based on a microprobe according to claim 4, characterized in that, The testing instrument also includes an analog-to-digital converter, a microcontroller unit, a direct digital frequency synthesizer, and a vibration structure; When performing low- to high-frequency signal testing, the voltage signal processed by the test module is acquired at high speed by an analog-to-digital converter and then entered into the microcontroller unit for calibration to calculate the potential value of the charged body. When performing low-frequency signal testing, the AC signal output by the direct digital frequency synthesizer controlled by the microcontroller directly drives the vibrating structure, causing the grounding electrode, which is rigidly connected to the vibrating structure, to vibrate periodically. Subsequently, after I / V conversion and subsequent processing, the signal is output to the analog-to-digital converter. The microcontroller also needs to perform amplitude signal processing on the voltage signal, and the amplitude is proportional to the magnitude of the electric field on the surface of the charged body being tested, so as to calculate the potential value of the charged body.

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