基于MEMS的距离自适应型非接触静电仪

静电场测量是检测物体是否携带过量静电最直接的手段，对于静电防护具有重要意义。传统的静电仪主要依赖固定距离测量，在被测物难以维持静止或不容易靠近时，距离改变引起灵敏度变化，造成测量误差。该文基于微机电系统电场传感器，提出一种可根据测试距离自适应调整灵敏度的静电测量思路：通过超声波模块测量被测物的距离，然后通过单片机查找对应的灵敏度系数，结合电场测试结果计算被测电压。针对研制的静电仪，该文提出基于实验室标定及现场标定相结合的校准方法，搭建了动态灵敏度标定系统，计算出不同测试距离、不同被测物尺寸的传感器灵敏度系数对应关系。与定距测量的传统静电仪相比，该文通过灵敏度动态标定，实现了更精确的非接触表面静电压测量；采用微机电系统电场敏感元件，具有体积小、功耗低、易集成、可批量化制备等优点，封装后无裸露可动部件，可靠性高。经第三方计量检测，在不同测试距离下的平均误差为–2.98%。

A Daptive-distance Noncontact Electrostatic Meter Based on MEMS Technology

Electrostatic field measurement is the most direct method to detect whether an object carries excessive static charge. Traditional electrostatic meters mainly rely on fixed distance measurement. While the measured object is difficult to maintain still or not easy to approach, the distance change causes a sensitivity change and results in a measurement error. Based on the micro-machined electric field sensor, this paper proposes an electrostatic measurement idea that the meter adjusts the sensitivity adaptively according to the tested distance: measure the distance of the object through the ultrasonic module, to find the corresponding sensitivity coefficient through the microprocessor, and then to calculate the measured voltage accompany the electric field result. For the developed meter, this paper proposes a calibration method based on a combination of laboratory calibration and site calibration, builds a dynamic sensitivity calibration system, and calculates the corresponding relation of sensor sensitivity coefficients of different test distances and different measured object sizes. Compared with the conventional measurements in a fixed distance, this paper achieves more accurate non-contact surface static voltage measurement by means of sensitivity dynamic calibration. In the meanwhile, the micro electric field sensing element has the advantages of small size, low power consumption, easy integration, and capable of mass manufacturing. According to the third-party test, the average error at different test distances is –2.98%.