Development Of LED Luminous Parameter Testing System

Light Emitting Diodes have many advantages such as small divergence angle,low power consumption,long life time,fast response,used widely in the field of lighting.At the beginning of the research,international and national material is referred to master the measuring principle of Lumi.nous flux and design an automatic calibrating system for LED measuring.The repeated experiments results show that the system can achieve the measurement of LED luminous parameters.Using the one pair of CCD describe the geometric axis of the LED,detecting rod is adopted to acquire the reference axis.The geometric axis of the LED is positioned coincident with the reference axis by positioning device;in this manner;the geometrical axis can pass through the centre of the detector apertures and perpendicular to the surface of the detector,so it can improve the measurement accuracy.Then,a design of two phase stepping motor driver based on THB6128 is introduced,the control chip gets the appropriate frequency of PWM pulses to set the speed of the turntable.Two dimensional turntable in the process of rotation,the detector collects the light signal,and the collected data is transmitted to the host computer through the serial port,the host computer analyzes and processes the received data.So the luminous intensity curve of each plane is obtained with the rotation of the turntable.At last,the software of the upper computer is developed by using C#,according to the segmentation algorithm of spherical zone to calculate the total luminous flux of LED,polar and rectilinear coordinates of the distribution curve of luminous intensity are drawn,meanwhile,the host computer saves real-time values of the luminous intensity,so it can provide valuable data for the subsequent analysis.By building the testing platform,the two groups of the standard LEDs are tested for many times.As can be seen from the test results,the system can be realized as LED luminous flux and luminous intensity measurement.Furthermore,the results show good repeatability,and it has positive significance for the improvement.