基于单片机的LED智能补光台灯设计
摘 要随着现代社会的发展,中国青少年的近视率一直居高不下,成为困扰中国家庭的主要问题。随着科学技术的进步,科学家希望通过人工干预和治疗,从根本上解决近视问题。然而现代医学的发展虽然可以解决很多曾经困扰人类的疑难问题,却仍然不能从根源上预防和祛除近视。我们通过对影响视力的各种因素进行实验,发现造成青少年视力下降的最主要根源是灯光。传统护眼灯为了达到提高频率的目的,使用了高频镇流器,使得护眼灯的电磁辐射远比一般的电器高得多,是手机、电脑的数倍甚至数十倍,严重影响视力。而LED照明技术的出现,为我们提供了消除仅是问题的途径。本文基于单片机控制的智能补光系统,全天候模拟出上午9、10点钟自然光照,完全杜绝频闪、辐射和眩光,有效消除传统光源中紫外线、红外线,能有效降低因光线变暗或变亮对人眼睛的伤害,可以有效减少对电能的消耗,节能环保。 针对现代社会近视率居高不下的现象,提出了基于MCS-51单片机的LED智能补光系统对外界光线的自动采集和调整,以减少由于外界光线变亮变暗对人眼的伤害。实验结果表明LED灯管的亮度可以柔和地根据外界光线的变化而变化,不存在闪烁和刺眼现象。通过光敏电阻采集外部光照和光通量的变化,采集到的变化值经过和基准值比较后送到单片机进行运算,由MCU控制数字量的输出,从而改变流经LED灯管的电流,以此来调整LED的亮度,以接近自然光的状态运行,实现智能补光。 关键词:台灯 光度 PWM调光 自动调节With the development of modern society, the China youth myopia rate has been high, become the main problems of Chinese family. With the progress of science and technology, scientists hope to use artificial intervention and treatment, fundamentally solves the problem of myopia. However, although the development of modern medicine can solve many difficult problems have plagued mankind, myopia still cannot prevent from the source and eliminate. Our experiments on various factors affecting the eyesight, found that the most major causes of adolescent eyesight to drop is light. The traditional eye protection lamp in order to improve the frequency of the use of high frequency ballasts, electromagnetic radiation, make the eye protection lamp is much higher than the general electrical appliances, mobile phone, computer is several times even dozens of times, seriously affect vision. LED lighting technology, provides us with a way to eliminate is only part of the problem. In this paper, intelligent lighting system based on single chip microcomputer, all-weather simulate the morning of the 9, ten o'clock, natural light, completely eliminate the stroboscopic, radiation and glare, the effective elimination of traditional light sources in the ultraviolet, infrared, can effectively reduce the light dimming or brightening of the human eye damage, can effectively reduce the consumption of electricity, energy saving environmental protection.In the modern society high myopia phenomenon, put forward LED intelligent supplemental lighting system of MCS-51 single chip microcomputer automatic acquisition and adjustment of the external light based, to reduce due to external light dimmed on human harm. The experimental results show that the brightness of the LED lamp can be gently according to the changes of the external light changes, does not exist and dazzling flashing phenomenon. Light sensitive resistance acquisition of external light and luminous flux changes, changes in the value of the process and the reference value comparison is sent to the microcontroller operation, the output is controlled by MCU digital quantity, thus changing the current flowing through the LED lamp, the brightness in order to adjust the LED, to state run close to natural light, the realization of intelligent lighting.目录引言 一、 LED智能补光灯原理··························二、系统硬件电路设计······························2.1主控电路的系统································2.2恒流驱动系统···································2.3 调光方案的选择······························三、自动控制3.1光敏电阻反馈部分·············································3.2 ADC0809模数转换部分···············································3.3 调光系统······································四、软件设计4.1 总体框图·····································4.2 主要程序······································五、 总结附录:作品照片引言LED照明又称固态照明,作为继白炽灯、荧光灯后的第三代照明技术,具有节能、环保、安全可靠的特点,固态光源是被业界看好的未来十年替换传统照明器具极具潜力的新型光源,代表照明技术的未来。发展新固态照明,不仅是照明领域的革命,而且符合当前政府提出的“建设资源节约型和环境友好型社会”的要求。LED台灯就是以LED(Light Emitting Diode)即发光二极管为光源的台灯,LED是一种固态的半导体器件,它可以直接把电转化为光。LED台灯是典型的绿色照明光源产品,作为国家绿色照明推广使用的产品,具有广阔的应用前景。在实际的应用中,发现LED灯在周边亮度大时依然以同一功率发光,存在电能浪费。另外一方面,因为LED的发热量和电流存在正相关的关系,发热影响了LED的寿命,所以在不必要的亮度下也减少了LED的寿命。然而,当LED在周边亮度小时,LED灯不能提供足够和恰当的光度,这样又影响了阅读,造成视觉疲劳。PWM方法的基本思想就是利用单片机具有的PWM端口,在不改变PWM方波周期的前提下,通过软件的方法调整单片机的PWM控制寄存器来调整PWM的占空比,从而控制充电电流。本方法所要求的单片机必须具有ADC端口和PWM端口这两个必须条件,另外ADC的位数尽量高,单片机的工作速度尽量快。在调整充电电流前,单片机先快速读取充电电流的大小,然后把设定的充电电流与实际读取到的充电电流进行比较,若实际电流偏小则向增加充电电流的方向调整PWM的占空比;若实际电流偏大则向减小充电电流的方向调整PWM的占空比。本文介绍了以STC89C51为控制核心,通过光敏电阻感应光度,并利用PWM调光技术对LED进行光度的自动调节。一、 LED智能补光灯原理交流电源的频率为50赫兹,会使台灯产生每秒钟50回合的一明一暗的频闪。频闪导致眼睛瞳孔括约肌不停地张合,使眼球老损、变形,最终引发近视。而所谓的护眼灯是通过一种高频镇流器,把频闪从50次变成3至5万次,但其实并没有真正消除频闪,并不能真正保护眼睛。可以说,频闪是近视的罪魁祸首。LED低压直流发光技术,采用直流电源,完全无频闪;由光电传感器、红外传感器和单片机构成智能补光系统,可根据环境光变化自动调节光照强度,无论外界如何变化,始终保持恒定适眼光源。二、系统硬件电路设计基于C51单片机和PWM调光的LED台灯是以STC89C51作为主控芯片继而进行自动控制的。在自动控制时,通过ADC0809模拟-数字转换芯片不断检验光敏电阻的电压来间接测量感应光度,将电压和预设的阈值进行对比,调整PWM的占空比对LED的电流进行控制,从而实现了对光度的自动调节。总体框图如下图。图1.1光敏电阻传感器A/D转换模块AT89C52单片机D/A转换模块驱动电路超亮白光LED光电开关侦测电路2.1主控电路的系统主控芯片采用AT89C51单片机芯片,AT89C51单片机芯片有40个外部I/O口, 可用作对外部硬件的控制接口。其中P0.0-P0.7八个I/O口外接10K的电阻作为上拉电阻。40引脚为电平引脚外接五伏电压,20引脚为接地引脚,18和19引脚为外部晶振接口,为芯片提供晶振,9引脚为外部复位电路接口,P1.0-P1.7作为DA模块控制端口,P2.0-P2.7作为AD模块的控制端口。2.2恒流驱动系统 外部光线采集主要用到的传感器为:光敏传感器。光敏传感器实时监