體積表面電阻率測試儀工作原理

   根據(jù)歐姆定律，被測電阻Rx等于施加電壓V除以通過的電流I。傳統(tǒng)的高阻計(jì)的工作原理是測量電壓V固定，通過測量流過取樣電阻的電流I來得到電阻值。從歐姆定律可以看出，由于電流I是與電阻成反比，而不是成正比，所以電阻的顯示值是非線性的，即電阻無窮大時(shí)，電流為零，即表頭的零位處是∞，其附近的刻度非常密，分辨率很低。整個(gè)刻度是非線性的。又由于測量不同的電阻時(shí)，其電壓V也會(huì)有些變化，所以普通的高阻計(jì)是精度差、分辨率低。

體積表面電阻率測試儀是同時(shí)測出電阻兩端的電壓V和流過電阻的電流I，通過內(nèi)部的大規(guī)模集成電路完成電壓除以電流的計(jì)算，然后把所得到的結(jié)果經(jīng)過A/D轉(zhuǎn)換后以數(shù)字顯示出電阻值，即便是電阻兩端的電壓V和流過電阻的電流I是同時(shí)變化，其顯示的電阻值不象普通高阻計(jì)那樣因被測電壓V的變化或電流Ｉ的變化而變，所以，即使測量電壓、被測量電阻、電源電壓等發(fā)生變化對其結(jié)果影響不大，其測量精度很高()，從理論上講其誤差可以做到零，而實(shí)際誤差可以做到千分之幾或萬分之幾。

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.