The Design Of LED Lamp Light Intensity Detection

As "the Twelveth Five-Year plan" energy conservation and emission reductionforward, LED light source of the luminous efficiency constantly breakthroughs. The StateDevelopment and Reform Commission announced that ordinary lighting incandescentlamp will be gradually withdrawn from the market in the next five years. The wideapplication of LED light source, it is different from testing method of the traditional lightsource. The LED light source detection need to put forward the new requirements, tocomplete testing standards and testing methods. It is beneficial to the integration ofresources, and to accelerate development LED products. Therefore, photoelectricdetection of LED sources is very important to the LED industrial development.LED street lamp is the one of LED light sources. The size of LED lamp is differentfrom normal light sources. LED lamp has much bigger size. LED lamp test environmentrequires strict conditions. Detection is difficult. Testing equipment requires high, highcost, and don’t have good generality. It is necessary to design a kind of relatively simple,high precision test system for LED lamp. Comprehensive analysis of the LED street lampdetection methods at home and abroad, this article adopt to lamps rotary distributionphotometer. Through fixed the light sensor, rotated the lamps to measure LED lamp lightintensity at the full space. It was finished correction of the light sensor, and gave thedesign scheme of light intensity in this article. It is deep describes the hardware circuitdesign and software control. Amplifier circuit, A/D conversion circuit, MCU and displaycircuit constitute the main circuit.Using a high sensitivity, good linearity of silicon photocell as light sensor, correctedafter human visual characteristic curve and cosine correction. It will be output linear andstable current signal. The weak current signal will be amplify to voltage signal afterpreamplifier (ICL7650) circuit. Through the filter, voltage signal will be amplify againafter the level 2 amplifier circuit. Because of big change of light signal, it needed analogswitch (MAX4602) to automatically adjust the preamplifier range. Take 16 bits highprecision A/D converter (MAX1134) circuit to realize the voltage signal converted intodigital signals. It is used MCU to control displaying the value through the LCD.According to the inverse distance square law, it was finished the software correction andcalibration illumination detection system.After the system test, verified the illumination detection system about LED street lamp basically meet the design requirements.