传感器设计--花盆缺水报警装置研讨.docVIP

花盆缺水报警装置 作 者： 指 导 老 师： 专 业： 测控技术与仪器 班 级： 学 号： 报告提交日期： 2012 年 9 月 目 录 一、前言··················································3 1、湿敏传感器的发展史·································3 2、湿敏传感器的种类及优缺点···························3 3、湿敏传感器发展趋势及应用···························4 二、选用湿敏传感器········································5 1、初定··············································5 2、实际选用···········································6 三、实验设计内容··········································6 1、设计题目···········································6 2、设计要求···········································6 3、设计原理···········································7 四、关于555的介绍·······································8 五、实 验 过 程··········································9六、负责主要的工作·······································10 1.选题···············································10 2．电路模拟仿真····································· 10 3.实验元器件的测试和电路调试························ 10 七、体会·················································11 八、致谢················································11九。参考文献············································· 11 十．附录·················································12 一、 前 言 1.湿敏传感器的发展史 早在18世纪人类就发明了干湿球和毛发湿度计，而电子式湿度传感器是近几十年．特别是近20年才迅速发展起来的。新旧事物的交替与人们的观念转变很有关系。由于干湿球、毛发湿度计的价格仍明显低于湿度传感器，造成一部分人对电子湿度传感器价格的不认可。正好像用惯了扫帚的人改用吸尘器时，总觉得花几百元钱买一台吸尘器有些不上算，不如花几元钱买把扫帚那样心理容易平衡。由于传统测湿方法在人们的脑海中印象太深了，一些人形成了只有干湿球湿度计才是准确的固有概念。有些用户拿干湿球湿度计来对比刚购得的湿度传感器，如发现示值不同，马上认为湿度传感器不准。须知干湿球的准确度只有5％一7％RH，不但低于电子湿度传感器，而且还取决于干球、湿球两支温度计本身的精度；湿度计必须处于通风状态：只有纱布水套、水质、风速都满足一定要求时，才能达到规定的准确度。湿度传感器生产厂在产品出厂前都要采用标准湿度发生器来逐支标定，最常用分流式标准湿度发生器来进行标定。所以希望用户在需要校准时也采用相同的方法，避免用准确度低的器具去校准或比对精度高的传感器。 1)、电解质湿敏元件 2)、高分子材料湿敏元件 3)、金属氧化物膜湿敏元件 4)、金属氧化物陶瓷湿敏元件 5)、热敏电阻式湿度传感器 6)、红外线吸收式湿度传感器 7)、微波式湿度传感器 8)、超声波式湿度传感器 　　湿度传感器的精度应达到±2%~±5%RH，达不到这个水平很难作为计量器具使用，湿度传感器要达到±2%~±3%RH的精度是比较困难的，通常产品资料中给出的特性是在常温(20℃±10℃)和洁净的气体中测量的。在实际使用中，由于尘土、油污及有害