体积表面电阻率测试仪工作原理

体积表面电阻率测试仪工作原理

   根据欧姆定律，被测电阻Rx等于施加电压V除以通过的电流I。传统的高阻计的工作原理是测量电压V固定，通过测量流过取样电阻的电流I来得到电阻值。从欧姆定律可以看出，由于电流I是与电阻成反比，而不是成正比，所以电阻的显示值是非线性的，即电阻无穷大时，电流为零，即表头的零位处是∞，其附近的刻度非常密，分辨率很低。整个刻度是非线性的。又由于测量不同的电阻时，其电压V也会有些变化，所以普通的高阻计是精度差、分辨率低。

体积表面电阻率测试仪是同时测出电阻两端的电压V和流过电阻的电流I，通过内部的大规模集成电路完成电压除以电流的计算，然后把所得到的结果经过A/D转换后以数字显示出电阻值，即便是电阻两端的电压V和流过电阻的电流I是同时变化，其显示的电阻值不象普通高阻计那样因被测电压V的变化或电流Ｉ的变化而变，所以，即使测量电压、被测量电阻、电源电压等发生变化对其结果影响不大，其测量精度很高()，从理论上讲其误差可以做到零，而实际误差可以做到千分之几或万分之几。

The working principle of 
 
According to the ohm's law, the resistance to be measured Rx is equal to the applied voltage V of the divided by the current through the I. Working principle of the traditional high resistance meter is to measure the voltage V fixed, by measuring the I current through the sampling resistor to get resistance. Can be seen from the ohm's law, due to the current (I) is inversely proportional to the resistance, rather than direct proportion, so the display value of resistance is nonlinear, when the resistance is infinite, current is zero, namely the header of the zero level is up, the scale is very near, resolution is very low. The whole calibration is nonlinear. By measuring the resistance of the different, its voltage V will be some changes, so ordinary high resistance meter is of poor accuracy and low resolution. 
 
The instrument to measure the resistance at the same time on both ends of the current through the resistor voltage V and I, through the internal voltage divided by the current calculation of large scale integrated circuit is complete, then put the results after A/D conversion to digital shows resistance, even at the ends of the resistance current through the resistor voltage V and I change at the same time, the display of the resistance is not like ordinary high resistance meter by measuring the change of the V voltage or current I change and change, so, even if the measured voltage, by measuring the resistance and voltage change has A little influence on the results, the measuring precision is very high (patent), in theory, the error can be zero, and the actual error can achieve A few parts per thousand or so few.