液体酸度测量

Research on liquid acidity measurement

在利用传感器进行液体酸度测量的时候,往往由于传感器电极本身的差异,或是由于放大电路元器件的精确度的不同而引起的系统误差总是不可避免的,同时,温度对于输出信号的影响也是不可忽视的。本文分别从软硬件2个方面来解决由于系统误差而引起的输出信号的飘移问题。文中首先简要介绍了pH值电极的工作原理,然后给出了2种软件标定和温度补偿方法,最后提供了一个pH值电极信号测量的后置放大电路的设计方案,并重点指出了在硬件电路实现时的一些关键问题,特别是第一级运放电路元件的选型问题。

When measuring liquid acidity by using a sensor, commonly it is unavoidable that there is system error for differences of sensor electrode-self, or for precision differences of amplifier circuit components, and not ignoring temperature effect to output signal at the same time. This text introduces how to solve excursion problem of output signal because of system error from software and hardware two aspects： First briefly introduces work theory of pH value electrode, then shows two ways of software demarcating and temperature compensating, last provides a designing scheme of postposition amplifier circuit about pH value eletrode signal measuring and emphasizes pointing out some key problems about implementing hardware circuit, specially choosing components model problem of first amplifier circuit.