The scheme of long-term power-on aging test of LED lighting products introduced in this paper mainly explains how to combine the hardware products in the system and the main monitoring software to achieve the maximum effect of power supply in the aging system and improve multiple The simultaneity and automation of LED product aging tests, the most accurate monitoring data and the goal of maximizing labor cost savings. The system has been applied to actual aging tests and will be further promoted and applied in the LED industry.
The principle of LED illumination
The Chinese LED industry started in the 1970s. After more than 30 years of development, China's LED industry has initially formed a relatively complete industrial chain including the production of LED epitaxial wafers, the preparation of LED chips, the packaging of LED chips and the application of LED products.
LED-illuminated LEDs are made of III-IV compounds such as GaAs (gallium arsenide), GaP (gallium phosphide), GaAsP (phosphorus gallium arsenide), and the core is the PN junction. Therefore, it has the IN characteristic of a general PN junction, namely forward conduction, reverse cutoff, and breakdown characteristics. In addition, it has luminescent properties under certain conditions. At the forward voltage, electrons are injected into the P region from the N region, and holes are injected into the N region from the P region. A part of the minority carriers (small children) entering the other area is combined with the majority carriers (multiple sub-) to emit light. Assuming that luminescence occurs in the P region, the injected electrons directly composite with the valence band holes to emit light, or are first captured by the luminescent center and then recombined with the holes. In addition to this luminescent composite, some electrons are trapped by the non-luminous center (this center is near the middle of the conduction band and the intermediate band), and then recombined with the holes, and the energy released each time is not large, and visible light cannot be formed.
Market requirements for LED lighting products
Some people call it a long-life lamp, which means a lamp that never goes out. Solid cold light source, epoxy resin package, there is no loose part in the lamp body, there are no shortcomings such as filament light-emitting, heat deposition, light decay, etc. The service life can reach 60,000 to 100,000 hours, which is 10 times longer than the traditional light source. the above. Therefore, in order to achieve such an ideal state, anti-aging ability is particularly important.
First, the aging test of LED lighting products
The long-term aging test of LED backlight and lighting products is a very important test. Through the aging test, it is possible to detect the light fading, color temperature change, leakage and other faults that LED products may produce in the long-term use, which is beneficial to the stability of product performance. ITECH power and aging test software is mainly used for aging test of LED backlights and lighting products.
The results of the aging test of LED lighting products have a great relationship with the equipment used. The aging equipment and LED lighting products must ensure that the best aging time is determined under the condition of sufficient heat dissipation, and the data is monitored and compared by the aging system. In order to get the most accurate test data, to achieve the purpose of production and testing.
Second, the characteristics of the power supply and aging system applied in the LED aging test
Since the operating current of the LED is very special, a professional test system is required to obtain reliable data. In general, the power and aging systems used in LED aging tests should have the following characteristics:
1. The high-power ratio digital control DC power supply has a wide range of voltage and current usage, and has a wide range of applications;
2, can automatically control the rate of change of voltage and current, the maximum possible cost reduction;
3. High precision and high resolution;
4, low noise and ripple;
5, as small as possible, save space;
Third, the construction of LED aging test system
The LED aging test system is built by DC power supply and control software, as shown in the following figure:
Note: The power supply model used in the above figure is ITECH IT6720, and the aging control software model is ITECH IT9100.
The following figure is a screenshot of the interface observed by the user during the aging test using the test system:
In this interface, 16*32 channels of LED lighting or aging of backlight products can be observed simultaneously. There are a total of 16 groups of up to 32 channels, each represented by an array. Each square on the interface represents a channel, and when the channel is configured, the channel block is grayed out. The use of color to distinguish between different operating states enables the user to observe any subtle changes more clearly, simply and quickly during use. Generally speaking, in order to meet people's habits, the functions represented by different colors are as follows:
Gray: configured or running stopped
Yellow: Communication failed
Red: Run error
Green: communication and operation are normal
Fourth, the advantages of using this LED aging test program
Selecting a flexible ratio of power supply, combined with multi-channel aging monitoring software, can achieve aging monitoring test for hundreds of LEDs at the same time.
The advantages of this program are:
1) The power supply is small and standard, and can be placed on a standard instrument cabinet. The aging system can be easily designed and placed according to the actual situation. Avoid the tedious work of special custom aging test system cabinets;
2) The programmable power supply used is easy to operate and has high precision and stability.
3) Intelligent fan control with low noise;
4) The aging value can be set in batches by software and the working status of each LED lighting product can be detected;
5) When the aging test bench continues to work for a long time, it is generally 72H, no need to be on duty;
6) Using monitoring software, data can be automatically recorded for analysis;
7) The price is reasonable, the construction is simple, and the future is highly scalable, which is very suitable for applications in this field.
V. Conclusion
The characteristics of LED illumination put forward special requirements for the scheme of aging test of LED lighting products. The LED burn-in test solution described above can be widely used in LED lighting and aging test of backlight products, and the performance is perfect. Select the professional power supply and control software for the LED industry, build the above test system, and get the most accurate and effective data.
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