CN220438442U - Non-contact electrostatic voltage testing device - Google Patents
Non-contact electrostatic voltage testing device Download PDFInfo
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- CN220438442U CN220438442U CN202322036742.7U CN202322036742U CN220438442U CN 220438442 U CN220438442 U CN 220438442U CN 202322036742 U CN202322036742 U CN 202322036742U CN 220438442 U CN220438442 U CN 220438442U
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Abstract
The utility model discloses a non-contact electrostatic voltage testing device which comprises a direct induction type sensor, an emitter follower, a charge amplifier, a voltage amplifier and a charge-voltage conversion circuit, wherein the output end of the direct induction type sensor is connected with the input end of the emitter follower, the output end of the emitter follower is connected with the input end of the charge amplifier, the output end of the charge amplifier is connected with the input end of the charge-voltage conversion circuit, and the output end of the charge-voltage conversion circuit is connected with the input end of the voltage amplifier. The testing device has wide low-frequency range and high testing precision.
Description
Technical Field
The utility model relates to the technical field of electromagnetic testing, in particular to a non-contact electrostatic voltage testing device.
Background
Static electricity brings serious potential safety hazards to many industries due to concealment, potential, randomness, complexity and destructiveness, and the related fields include aerospace, ship transportation, petroleum, chemical industry, gunpowder production, microelectronic technology and the like. The test of electrostatic voltage is an important parameter for representing electrostatic power supply, and is required to test electrostatic parameters in electrostatic scientific research and process design, test, construction, production and other processes of electrostatic application. In order to check the design and manufacturing quality of static sensitive electronic products, it is also necessary to test the static discharge sensitivity of these products. It should be noted that some static parameters, although theoretically calculated, are often complex, and theoretical calculation alone is difficult to obtain satisfactory results for engineering needs, and must rely on testing.
Electrostatic voltage testing is divided into two methods, contact measurement, which is applicable to conductors, and non-contact measurement, which is applicable to non-conductors or contact-inhibited objects. The non-contact measurement has a plurality of influencing factors, not only has the influence of the self characteristic of the instrument on the test precision, but also has the influence of the calibration device of the test instrument on the test result, and also has the requirement of ensuring the test precision, and various factors should be considered in practical application. At present, the non-contact sensor has direct induction type, rotary vane type, variable capacitance type, air ionization type and the like, and the existing finished product instrument has the advantages and disadvantages, but has the common problems of zero drift, interference influence, narrow frequency range and the like, and has larger signal test error with quicker change, so that the instrument has no monitoring function.
Disclosure of Invention
In order to overcome the defects of zero drift, interference influence and narrow frequency range existing in the prior art, the non-contact electrostatic voltage testing device is provided, and the surface voltage of a charged body is tested by using a distorted electric field generated between a probe and the tested charged body, so that the testing precision is improved.
In order to solve the problem of narrow frequency range, the utility model provides the following technical scheme:
the utility model provides a non-contact electrostatic voltage testing arrangement, includes direct induction type sensor, emitter follower, charge amplifier, voltage amplifier and charge-voltage conversion circuit, the input of emitter follower is connected to the output of direct induction type sensor, and the input of charge amplifier is connected to the output of emitter follower, and the input of charge-voltage conversion circuit is connected to the output of charge amplifier, and the input of voltage amplifier is connected to the output of charge-voltage conversion circuit.
In the scheme, the direct induction type sensor is adopted to detect the charge of the charged body to be detected, the testing range can be adjusted by adjusting the distance between the direct induction type sensor and the charged body to be detected, and the emitter follower, the charge amplifier and the voltage amplifier are matched with each other, so that a wider low-frequency bandwidth is realized, namely, the frequency range is enlarged, and the frequency range can reach 2kHz through testing.
As an example of a possible way, the charge-voltage conversion circuit comprises two diodes, an NPN transistor and a PNP transistor, the two diodes being connected in series, the output of the charge amplifier being connected between the two diodes, the base of the NPN transistor being connected to the positive terminal of one diode, the base of the PNP transistor being connected to the negative terminal of the other diode, the emitter of the NPN transistor being connected to the emitter of the PNP transistor and being connected to the input of the voltage amplifier.
The direct induction type sensor collects charges, the charges are converted into voltage signals through the charge-voltage conversion circuit, and the circuit structure can be simplified while the conversion is realized by adopting the circuit structure, and the cost is kept low.
In order to solve the problem of zero drift, the embodiment of the utility model provides the following technical scheme:
the zero drift suppression circuit comprises a first resistor, a second resistor, a third resistor and a first variable resistor, wherein one end of the first resistor is connected with the input end of the emitter follower, one end of the second resistor is connected with the negative electrode of the power supply, the other ends of the first resistor and the second resistor are connected with the first variable resistor, one end of the third resistor is connected with the first variable resistor, and the other end of the third resistor is connected with the positive electrode of the power supply.
In the scheme, the zero drift suppression circuit is arranged, so that the problem of zero drift is solved, the stability of the testing device is improved, and the zero drift suppression circuit with the structure is simple in structure and high in reliability.
In a further optimized scheme, the distance between the direct induction type sensor and the charged body to be measured is 20-50 mm. In this scheme, through inject the distance between direct induction type sensor and the electrified body of survey, both ensured the safety in utilization, ensured certain test range again, satisfied the application demand.
In a further optimized scheme, the charge-voltage conversion circuit further comprises an A/D converter, and the output end of the charge-voltage conversion circuit is connected with the input end of the A/D converter. In this scheme, through setting up the AD converter, convert analog signal into digital signal, be convenient for follow-up processing, design such as warning suggestion, reinforcing testing arrangement's practicality.
In a further optimized scheme, a protection resistor is arranged between the direct induction sensor and the emitter follower. In this scheme, through setting up protection resistance, when outer electrified body (e.g. human body) bumps by mistake or is too close to the probe, prevent direct or corona discharge to emitter follower input, guarantee safety in utilization.
In order to solve the problem of electromagnetic interference, the embodiment of the utility model provides the following technical scheme:
the direct induction type sensor, the emitter follower, the charge amplifier, the voltage amplifier and the charge-voltage conversion circuit are all arranged in the shielding shell.
In the scheme, the shielding shell is arranged, so that the induction potential on the probe electrode is reduced, and the anti-interference capability is improved.
In an embodiment, the direct induction sensor includes a test probe, a coupling capacitor, an input resistor and an input capacitor, wherein the input resistor is connected in parallel with the input capacitor, one end of the input resistor is grounded, the other end of the input resistor is connected with the test probe, and the coupling capacitor is an equivalent capacitor between the test probe and ground.
In an embodiment, the emitter follower includes a first integrated operational amplifier chip, a forward input terminal of the first integrated operational amplifier chip is connected to an output terminal of the direct induction sensor, a reverse input terminal of the first integrated operational amplifier chip is grounded through a fourth resistor, and the first integrated operational amplifier chip is connected to a second variable resistor.
In an embodiment, the charge amplifier includes a second integrated operational amplifier chip, a reverse input end of the second integrated operational amplifier chip is connected to an output end of the first integrated operational amplifier chip, a capacitor is connected between the reverse input end and the output end, and a positive input end of the second integrated operational amplifier chip is grounded through a fifth resistor.
In an embodiment, the voltage amplifier includes a third integrated operational amplifier chip, wherein an inverting input terminal of the third integrated operational amplifier chip is connected to emitters of the NPN transistor and the PNP transistor through a sixth resistor, and an inverting input terminal of the third integrated operational amplifier chip is connected to an output terminal thereof through a seventh resistor, and a non-inverting input terminal of the third integrated operational amplifier chip is grounded through an eighth resistor.
Compared with the prior art, the utility model has the following beneficial effects:
the current non-contact dynamic range is smaller than 100Hz, the circuit design of the utility model adopts a quasi-charge amplifier, the input end adopts a zero drift suppression circuit to suppress zero drift, and the output signal of the charge amplifier adopts a direct current amplifier to amplify, thereby ensuring wider low frequency band. The test probe is of a direct induction type, and has the advantages of a certain frequency range, which is superior to a general non-contact electrostatic voltmeter, the dynamic range of the device can reach 2kHz, and the output amplitude is 0.5-1.0V.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present utility model and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a non-contact electrostatic voltage testing apparatus according to the present utility model.
Fig. 2 is an electrical schematic diagram of a direct induction sensor in an embodiment.
Fig. 3 is an electrical schematic diagram of a non-contact electrostatic voltage testing apparatus according to an embodiment.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present utility model.
As shown in fig. 1, the non-contact electrostatic voltage testing apparatus provided in this embodiment includes a direct induction sensor, an emitter follower, a charge amplifier, a voltage amplifier and a charge-voltage conversion circuit, wherein an output end of the direct induction sensor is connected to an input end of the emitter follower, an output end of the emitter follower is connected to an input end of the charge amplifier, an output end of the charge amplifier is connected to an input end of the charge-voltage conversion circuit, and an output end of the charge-voltage conversion circuit is connected to an input end of the voltage amplifier.
The direct induction type sensor is close to the charged body to be detected, preferably keeps a distance of 20-50mm from the charged body to be detected, not only can meet the test requirement, but also can ensure the application safety. The direct induction type sensor detects the electric charge released by the charged body to be detected, the electric charge is amplified by the emitter follower, the charge amplifier and the voltage amplifier, and finally the electric charge is converted into a voltage signal by the charge-voltage conversion circuit, so that the static voltage test is realized.
In order to further improve the test precision and facilitate signal processing, an a/D converter may be further disposed at the output end of the charge-voltage conversion circuit to convert the voltage analog signal into a voltage digital signal, and after processing into the digital signal, more functional designs may be implemented, for example, by configuring an alarm, and when the tested voltage is higher than, for example, 1KV, an alarm signal is sent.
The basic principle of static potential test of the direct induction type sensor is shown in figure 2. In the figure, T is a test probe, L is an equivalent input circuit of a sensor, and C w Is the coupling capacitance between the test probe and the charged body to be tested, R b And C b The input resistance and the input capacitance of the sensor, respectively. Due to the electric field of the charged body to be measured, an induced potential is generated on the probe T. The circuit in the figure can be seen as follows: c (C) w Is with C b In series with R b Is C b If the ground potential of the charged body to be measured is U, the probe ground voltage is: changing the distance between the probe and the charged body to be measured, i.e. changing the coupling capacitance C between the two w I.e. the range or reading of the sensor can be changed.
As shown in FIG. 3, the emitter follower employs an A1 (e.g., LC3140 integrated operational amplifier) chip, the positive input of the A1 chip passing through a protection resistor R 1 The output end of the direct induction type sensor is connected with the protection resistor R 1 Can prevent direct or corona discharge to the input end of the design follower when the charged body to be tested is mistakenly bumped or is too close to the direct induction sensor. The reverse input end of the A1 chip passes through a resistor R 2 The A1 chip is also connected with a variable resistor R W1 。
The charge amplifier adopts an A2 chip (LC 3140 integrated operational amplifier), the reverse input end of the A2 chip is connected with the output end of the A1 chip, and a capacitor C is connected between the reverse input end and the output end 2 The positive input of the A2 chip is grounded through a resistor (fifth resistor).
The charge-voltage conversion circuit comprises two diodes (V 1 、V 3 ) NPN triode V 2 And a PNP triode V 4 The two diodes are connected in series, the output end of the A2 chip is connected between the two diodes, the base electrode of the NPN type triode is connected to the positive end of one diode, the base electrode of the PNP type triode is connected to the negative end of the other diode, the emitter electrode of the NPN type triode is connected with the emitter electrode of the PNP type triode, and the emitter electrode of the NPN type triode is connected with the input end of the voltage amplifier. Diode V 1 The positive electrode of the (E) and the collector electrode of the NPN triode are connected with the positive electrode E-of the power supply, and the diode V 3 The negative terminal of the PNP triode and the collector of the PNP triode are both connected with the positive electrode E+ of the power supply. The power supply adopts + -5V power supply.
The voltage amplifier adopts an A3 chip (LC 3140 integrated operational amplifier), the reverse input end of the A3 chip is connected with the emitters of the NPN type triode and the PNP type triode through a resistor (sixth), the reverse input end of the A3 chip is connected with the output end of the A3 chip through a resistor (seventh resistor), the positive input end of the A3 chip is grounded through a resistor (eighth resistor), and the voltage U of the output end of the A3 chip 0 I.e. the voltage measured by the test device. Voltage U 0 Obtained by calibration.
In order to restrain the zero drift, the device also comprises a zero drift restraining circuitThe suppression circuit comprises a first resistor R 4 A second resistor R 3 Third resistor R 5 And a variable resistor R W2 First resistor R 4 A second resistor R connected to the positive input terminal (input terminal of emitter follower) of the A1 chip 3 One end of (a) is connected with the negative electrode of the power supply, and a first resistor R 4 A second resistor R 3 Is connected with the variable resistor R at the other end W2 Connected with a third resistor R 5 One end of (a) is connected with a variable resistor R W2 The other end is connected with the positive electrode of the power supply. First resistor R 4 By R W2 Obtaining a voltage division value, adding the voltage division value into a signal input end, and adjusting a variable resistor R W2 The input is made to receive a small signal in the opposite direction to cancel the drift signal. First resistor R 4 If the value is 1TΩ, the signal added to the input terminal is pA level, and normal signal amplification is not affected.
As shown in fig. 3, the circuit is also provided with zeroing and K 1 、R 6 And the zero resetting button is used for resetting the circuit.
After the non-contact electrostatic voltage testing device is developed, the accuracy of the device is calibrated by adopting a standard high-voltage source in a national defense key laboratory of a strong electromagnetic environment simulation and protection technology, and the distance between the front end of a sensor and a measured object is calibrated to be 50mm. Tested: the frequency range can reach 2kHz; at a test distance of 50mm, the measuring range can be practically tested to about + -5 kV; the measurement error is smaller than the maximum allowable error, and the minimum value of the measurement error is 1%, the maximum value is 1.8%, and the average value is 1.33%. And when the output is greater than 1kV, the alarm function is normal.
The foregoing is merely illustrative of the present utility model, and the present utility model is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present utility model.
Claims (10)
1. The non-contact electrostatic voltage testing device is characterized by comprising a direct induction type sensor, an emitter follower, a charge amplifier, a voltage amplifier and a charge-voltage conversion circuit, wherein the output end of the direct induction type sensor is connected with the input end of the emitter follower, the output end of the emitter follower is connected with the input end of the charge amplifier, the output end of the charge amplifier is connected with the input end of the charge-voltage conversion circuit, and the output end of the charge-voltage conversion circuit is connected with the input end of the voltage amplifier.
2. The device according to claim 1, wherein the charge-voltage conversion circuit comprises two diodes, an NPN transistor and a PNP transistor, the two diodes are connected in series, an output terminal of the charge amplifier is connected between the two diodes, a base of the NPN transistor is connected to a positive terminal of the one diode, a base of the PNP transistor is connected to a negative terminal of the other diode, an emitter of the NPN transistor is connected to an emitter of the PNP transistor, and an input terminal of the voltage amplifier is connected.
3. The device for testing the non-contact electrostatic voltage according to claim 2, further comprising a zero drift suppression circuit, wherein the zero drift suppression circuit comprises a first resistor, a second resistor, a third resistor and a first variable resistor, one end of the first resistor is connected with the input end of the emitter follower, one end of the second resistor is connected with the negative electrode of the power supply, the other ends of the first resistor and the second resistor are connected with the first variable resistor, one end of the third resistor is connected with the first variable resistor, and the other end of the third resistor is connected with the positive electrode of the power supply.
4. The device of claim 1, further comprising an a/D converter, wherein an output of the charge-to-voltage conversion circuit is coupled to an input of the a/D converter.
5. The non-contact electrostatic voltage testing apparatus according to claim 1, wherein a protection resistor is provided between the direct induction sensor and the emitter follower.
6. The device of claim 1, further comprising a shield housing, wherein the direct induction sensor, the emitter follower, the charge amplifier, the voltage amplifier, and the charge-to-voltage conversion circuit are all mounted within the shield housing.
7. The device according to claim 1, wherein the direct induction sensor comprises a test probe, a coupling capacitor, an input resistor and an input capacitor, the input resistor is connected in parallel with the input capacitor, one end of the input resistor is grounded, the other end of the input resistor is connected with the test probe, and the coupling capacitor is an equivalent capacitor between the test probe and the ground.
8. The device according to claim 1, wherein the emitter follower comprises a first integrated operational amplifier chip, a forward input terminal of the first integrated operational amplifier chip is connected to an output terminal of the direct induction sensor, a reverse input terminal of the first integrated operational amplifier chip is grounded through a fourth resistor, and the first integrated operational amplifier chip is connected to a second variable resistor.
9. The device according to claim 8, wherein the charge amplifier comprises a second integrated operational amplifier chip, wherein an inverting input terminal of the second integrated operational amplifier chip is connected to an output terminal of the first integrated operational amplifier chip, a capacitor is connected between the inverting input terminal and the output terminal, and a non-inverting input terminal of the second integrated operational amplifier chip is grounded through a fifth resistor.
10. The non-contact electrostatic voltage testing apparatus according to claim 2, wherein the voltage amplifier comprises a third integrated operational amplifier chip, wherein an inverting input terminal of the third integrated operational amplifier chip is connected to emitters of the NPN transistor and the PNP transistor through a sixth resistor, and an inverting input terminal of the third integrated operational amplifier chip is connected to an output terminal thereof through a seventh resistor, and a non-inverting input terminal of the third integrated operational amplifier chip is grounded through an eighth resistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322036742.7U CN220438442U (en) | 2023-07-31 | 2023-07-31 | Non-contact electrostatic voltage testing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322036742.7U CN220438442U (en) | 2023-07-31 | 2023-07-31 | Non-contact electrostatic voltage testing device |
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| Publication Number | Publication Date |
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| CN220438442U true CN220438442U (en) | 2024-02-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202322036742.7U Active CN220438442U (en) | 2023-07-31 | 2023-07-31 | Non-contact electrostatic voltage testing device |
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| CN (1) | CN220438442U (en) |
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2023
- 2023-07-31 CN CN202322036742.7U patent/CN220438442U/en active Active
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