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随着现代工业的飞速发展,对湿度这个物理量的测量和控制提出了更高的要求。传统的毛发式和干湿球式湿度计由于存在响应速度慢、读数不便、操作繁杂、精度不高、寿命不长、无电信号输出等缺点,已不能满足人们更高的要求。为此研制用电阻或电容等电原理来工作的湿度传感器和测量仪器便成为课题被提出。电阻式多孔陶瓷型湿度计,国内已有不少单位在开发和生产,但就目前的实际进展来看,由于原材料及加工工艺的限制,存在着时漂和温漂问题,在线性度及要用交流源驱动方面也有不够方便之处,所以还难于推广应用。本文介绍一种薄膜电容型数字式湿度计。由于采用了高分子聚合物薄膜电容传感和脉冲宽度调制、大规模集成数字化转换、彩色液晶大屏幕显示和光耦合BCR 控制等技术,故有如下优点:1.能对0～99.9%RH 的全范围相对湿度测试;
With the rapid development of modern industry, higher requirements are put forward on the measurement and control of the physical quantity of humidity. Traditional hair and wet and dry bulb hygrometers have been unable to meet the higher requirements of people due to their short response time, inconvenient readings, complicated operation, low accuracy, short service life and no electric signal output. For this reason, it has been proposed to develop a humidity sensor and a measuring instrument which work on the principle of resistance or capacitance and the like. Resistive porous ceramic hygrometer, there are many units in the development and production, but the current actual progress, due to the constraints of raw materials and processing technology, there is the problem of drift and temperature drift, the linearity and to AC source drive also has not enough convenience, it is also difficult to promote the application. This article describes a film capacitance digital hygrometer. As a result of the use of polymer film capacitance sensing and pulse width modulation, large-scale integrated digital conversion, color LCD large screen display and optical coupling BCR control technology, it has the following advantages: 1. To 0 ~ 99.9% RH of the whole Range relative humidity test;