测量灯罩表面污染程度的电路设计

本文介绍了一种测量灯罩污染程度的电路.信号发生器产生PWM信号给驱动LED的电路,紫外LED灯发出紫外光照到车灯灯罩上,灯罩散射回来的光由滤光片滤除干扰光后,由光电二极管接收并将光强转换成电信号,该电信号送至放大电路,放大电路输出的电压传至选频电路,选出的电信号由整流滤波电路转换成直流电压,该直流电压送至电压比较器,并与电压比较器的阈值比较.当灯罩污染达到一定程度时,电压比较器输出高电平,启动车灯清洗器,清洗干净后,自动关闭清洗器.本设计的目的在于既能保持车灯表面清洁,又能减少对灯罩不必要的清洗,延长清洗器的寿命.

The circuit design about detecting the pollution degree of lamp shade

This article introduces a kind of circuit of detecting the pollution degree of lamp shade.The signal generator generates PWM signals to drive the driver circuit of LED,and the ultraviolet from the uv leds shines on the lamp shade and scattered light from the lamp shade is received by photoelectric diode after filtering out interference light by the filter and photodiode converts light into electrical signals and electrical signals are sent to the amplification circuit.Amplification circuit outputs voltage to frequency selective circuit,and the selected electrical signals are changed into dc voltage by the rectifier and filter circuit.The dc voltage is sent to the voltage comparator and compared with the voltage comparator＇s thresholds.When the lamp shade＇s polluti-on reaches a certain degree,the voltage comparator outputs high level.Starting the light cleaner,after wash,the cleaner will be automatically closed.The design＇s purpose is not only to keeping the lamp surface clean,but to reducing unnecessary cleaning to the lamp and prolong the life of the cleaner.