LED (Light Emitting Diode), whose basic structure is an electroluminescent semiconductor material, the core part is a wafer composed of a p-type semiconductor and an n-type semiconductor, and a diode that emits light by using injection electricity is called a light-emitting diode, that is, an LED. . Since the 2008 Beijing Olympic Games, after years of vigorous development, China's LED industry chain has begun to take shape, from the most upstream substrate, chip manufacturing, to packaging modules, to downstream products, and including LED driver and production. The surrounding industries, such as test equipment, have developed in different ways. LED testing has also become an important topic in the industry. 
LED product testing
Throughout the entire LED industry chain, from chip to packaging, finished products, no need to test the various photoelectric indicators of the product, all test procedures are carried out under the premise that the LED is powered on. However, almost all LED product manufacturers, LED test system integrators and LED certification companies pay great attention to the entire test system, but few people pay attention to the most basic test equipment - power supply. In the entire LED test system, the power supply is the most basic power supply device, and its function is not only as simple as power supply. If not properly selected, an ordinary power supply can generate a powerful surge current at the moment of startup. Although the time is extremely short, it is enough to cause unimaginable damage to the life of the LED to be tested. When testing with a small current, the ordinary power supply needs to wait for about 50s~1min to illuminate the product to be tested. According to this efficiency, it is calculated by testing 200 products per day on average, only for waiting time. For nearly three hours, this is a terrible number for LED companies facing huge competition every day. After investigating and testing the tests of many LED related manufacturers, it was found that the neglect of the power supply used in the LED test caused the above two situations. Therefore, Itech is working to improve the power supply used in the test to solve this problem.
Suppress surges and protect LEDs
After extensive research and analysis, Idex found that when using ordinary power supply for LED test, after the test is completed, the average life of LED will drop by 20-30%. The most immediate problem caused by the unintentional decline in product life during the test is that the downstream manufacturer cannot pass the aging verification of the product. In the investigation of the LED industry, many manufacturers were plagued by this problem. They constantly suspected that their test equipment had serious deviations, and even sent technicians to the client for on-site verification, which could not solve this problem. Who can think of it? Is the power supply causing this embarrassing situation? In this regard, Itech has proposed a simple and effective solution, using advanced technology to improve the function of the DC power supply to achieve the effect of suppressing the inrush current. Thereby protecting the LED. This concept has been realized in the ITECH IT6200 series power supply, the key is the "LED mode", a special function for the LED industry. An experiment can be used to test the 170 light LED light bar with the Itech IT6200 series DC power supply.
Connect the LED light bar to the IT6200 series DC power supply, turn on the power output in normal mode and LED mode, and supply power to the light bar. Under the condition that the current command is set to Iset=20mA, the current waveform captured by the oscilloscope They are as follows:
As can be seen from the figure, when the LED mode is selected for testing, the current of the IT6200 DC power supply series rises very smoothly to the set value at the start, and there is no surge current generated at all, so it will not cause any life of the LED product. influences. This figure also explains from the side why the ordinary power supply will reduce the life of the LED product during the test, and as the test current increases, the surge current generated by the ordinary power supply will also increase. Therefore, the use of the Itech IT6200 series DC power supply in LED related tests is the best choice.
Improve test efficiency
LED products often work in high-voltage, low-current environments, especially for products such as LED backlights, which typically use extremely small currents for testing. Ordinary power supplies can easily enter the current limit mode at a small current output, resulting in a delay in voltage rise time. The smaller the current and the higher the voltage, the longer the corresponding rise time. The Idx IT6200 series DC power supply has another unique test mode, low current mode, which solves this problem. In this mode, the IT6200 series power supply can be started with a small current and the voltage rises at a high speed. When this mode is turned on, the rise time of the output voltage is not changed by the magnitude of the microcurrent, which greatly speeds up the voltage rise time and shortens the time during which the LED product is lit, thereby improving test efficiency and productivity.
For example, in the test of a mobile phone backlight, the IT6200 series DC power supply is used to supply power to the test, and the test is performed at a current of 1 mA. Then, when the low current mode of the IT6200 series power supply is turned on and off, the voltage change waveforms are as follows: The two figures show:
It can be seen that when the test current is extremely small, if the Low current mode is not used (that is, equivalent to a normal power supply), after a long wait, the voltage still cannot rise to the set value, and the LED to be tested has not been tested. It is lit and cannot start testing. When the low current mode of the IT6200 series power supply is used, the voltage quickly rises to the set value, and then the LED to be tested is illuminated and the test is started. The function of the Idx IT6200 series power supply to improve test efficiency and productivity is very important for the production line.
LED product aging test
The aging test of the LED products mentioned above is an important test item in the LED industry chain, especially for lighting and backlight products. In the long-term aging process, automation is a necessary condition. In addition, simultaneous aging and real-time monitoring of multiple sets of products is the key to improving efficiency, and it is also the most urgent requirement for LED test companies for aging test systems.
Idex LED aging test system, with high power ratio of digitally controlled DC power supply, because of its wide voltage and current usage, it can be applied to the aging test of various LED products; IT9100 test software can observe at the same time Aging of 16*32 channels of LED lighting and backlighting products (a total of 16 groups of up to 32 channels per group). The software monitoring interface is very user-friendly and easy to test with simple color management. The square is used to represent the channel. When the channel is configured, the channel block is grayed out. Different operating states have different color representations. For example, green indicates that the communication and operation are normal, yellow indicates communication failure, and red indicates that the operation has an error. The Idex LED test system is extremely cost effective, and the test software automatically records data for engineers to analyze and identify problems.
LED driver power test
LED good products, need to cooperate with a good drive power to show the quality. Taking the LED street lamp as an example, because it is used outdoors, it can be imagined that the external environment that the driving power supply needs to bear is rather bad. The quality problems of several LED street lamps that have occurred recently have also pointed the finger directly to the driving power source. For testing in this area, Itech has a corresponding solution.
LED driver power testing includes electrical performance testing, reliability testing, environmental compliance testing, etc., where power and electronic loads are the two most basic test instruments. As a component that converts the power supply to a specific voltage and current to drive the LED to emit light, the AC power supply simulates the mains, and the electronic load is used to simulate the real-loaded LED lamp.
ITECH IT8800 series electronic load CR-LED mode real analog LED lights
The AC power used in the test, in addition to simulating the daily power supply, has an important task, namely analog voltage instability, to test the stability of the drive power. The ACex AC power supply can simulate surges and notches, the frequency can be adjusted within the range of 40-500HZ, and the phase angle is adjustable from 0-360° to meet the test requirements to the greatest extent.
Light-emitting diodes have a turn-on voltage, and the diode works only when the voltage applied across the diode is greater than the turn-on voltage. It is this characteristic that exists that the traditional CR mode of electronic load is not completely realistic to simulate the characteristics of LED lights. Therefore, the Itech IT8800 series electronic load is specially equipped with the CR-LED test mode for the LED driver power supply test, and the diode turn-on voltage setting is added inside the instrument to truly simulate the characteristics of the LED lamp. In addition to the new CR-LED mode, this series of electronic loads also has a CC/CV/CR/CZ test mode, which can be optimally selected according to different applications.
Through in-depth research on LED industry related tests, fully listening to the actual needs of engineers, based on more than 60 years of instrument manufacturing experience, Itech provides comprehensive test solutions for the LED industry.
Jinhu Weibao Trading Co., Ltd , https://www.weibaoxd.com