The Research Of LED Test System On In-circuit Tester In EMS Industry

LED (Light Emitting Diode) is widely used in industrial production, especially thatwe can see various colors everywhere of the LED in electronic products. In them thedifferent LED colors represents different work status. It will cause the back of theproduction process can’t go smoothly if we installed the wrong color LED on the pcba inthe process of production, and it will result in a large number of waste of manpower,material and financial resources etc.So it is very important that if we can check the defect of a LED color and functionalin the PCBA test stage. Traditional test method of enterprises is visual check, and it isobvious that there are some shortcomings. This work need the person must have theexperience, has a big workload, easy to visual fatigue. These will cause some LEDs misseddetection, eventually lead to low efficiency. At this time ICT (In-Circuit Test) equipmentcan solve this problem well if it can detect the LED color and its intensity automatically.The LEDIdentify has a great improve on the traditional test method. Traditional testmethod converts the led color to frequency or voltage. There are only0.2V~0.5Vdifference in two closed color, sometimes it is hard to distinguish them. When use thefrequency to representation the led color. The two closed colors only have1KHz~2KHzdifference also. But our LEDIdentify extracts the RGB tricolor value of the color by aTCS230color sensor, through improved the software algorithm, will compare the RGBtricolor value with the standard color value which are stored in the MCU and classification,MCU will output a binary code to represent the color. Our LEDIdentify has an analogyjudgment before given the test result, so it is more stable than the traditional tester identify.The LEDIdentify after many sets of test fixtures used in EMS factory show thatdistinguish results are accurate, stable, reduced the misjudgment rate, and can detect thedefective product effectively, reduce the repair rate. So it will save large manpower,material resources and financial resources for the enterprise.