Analysis of four key technologies for LED fluorescent lamp design

Fluorescent tubes are widely used in daily life, supermarkets, schools, office cities, subways, etc., but in public places that can be seen, you can see the use of fluorescent lamps! The energy-saving and energy-saving performance of LED fluorescent lamps has been widely recognized after a long period of publicity. However, many of the LED fluorescent tubes that have been bought at high prices are now in the same situation as cheap energy-saving lamps: energy saving. money! Moreover, it is a lot of waste of money. How to make the LED service life and brightness reach the standard of satisfactory use is a very meaningful topic! LED fluorescent tubes should maintain long life and high brightness. The problems to be solved are: power supply, LED light source, heat dissipation and safety.

a power source

The primary requirement of the power supply is high efficiency and high efficiency. If the heat is low, the stability will be high. Generally, there are two schemes of isolation and non-isolation in the power supply part. The isolation volume is large and the efficiency is low. In use, there are many problems in installation. It is not as good as the market prospect of non-isolated products. Here we mainly discuss non-isolation. Drive solution.
The non-isolated LED fluorescent lamp power supply is based on the A704WFT of Taiwan Guangpeng Technology Co., Ltd., and the MOS tube of the A704WFT is plugged in. The basic circuit is shown in Figure 1:

Figure 1: A704WFT non-isolated LED fluorescent lamp power supply

Power characteristics:
1. Mains power supply (85~265V), external MOS, power is not limited;
2, low power consumption, high efficiency, high power factor;
3, with load open circuit and short circuit protection, output overvoltage protection function, current ripple characteristics, output current is similar to DC DC, no lamp flash phenomenon, high load capacity, can drive up to 600mA current;
4, the customer has made 15W standard circuit, efficiency 88%, power factor 0.91, can pass CE certification, including EN55015 EMI test, lighting fixtures below 25W class C harmonic standard, EFT 1000V pulse group test, ESD 2000V static test. The 15-string application can control the output low voltage, eliminating the need for traditional large capacitors and controlling the output harmonics of the current.
5, A704's LED daylight application program is relatively mature and reliable, we can provide PCB line and EMC table reference for LED fluorescent lamp to improve the speed of customer design and development products!

Two LED light source

The LED lamp bead of Taiwan's patented structure is placed on the pin. The thermal energy passes through the silver foot directly to the tropical part produced by the chip node, and the traditional in-line product and the traditional patch product are cooled. There are qualitative differences, the node temperature of the chip will not accumulate, thus ensuring the good use of the light source bead, ensuring the long life of the light source bead, low light decay.
Although the traditional patch products can be connected to the positive and negative electrodes through the gold wire of the chip, and the thermal energy generated by the chip is connected to the silver foot through the gold wire, the conduction of heat and electricity is conducted by money, and the heat accumulation time is long. Will directly affect the life of LED fluorescent tubes.
The traditional heat transfer route and method of patch products are shown in Figure 2:

Figure 2: Heat transfer route and method of traditional patch products

The LED conduction route and method of Simings is shown in Figure 3:

Figure 3: Cummings' LED conduction route and method

The LED's patented heat dissipation structure allows the heat generated by the chip nodes to be quickly taken out, and no heat buildup occurs at the chip, thereby realizing long-life use of the LED light source bead. Moreover, in the life test of LED, Simings has made a complete experimental analysis for various complex application environments such as high and low temperature impact, over reflow, high temperature and high humidity, to ensure the low light decay of normal use. long life!

Three heat dissipation

The introduction of infrared radiation heat dissipation and application to fluorescent tubes is an important means to improve the service life of the lamps. In the heat dissipation consideration, we separate the heat dissipation of the LED light source bead and the heat dissipation of the power supply, and do not interfere with each other, thereby ensuring the rationality of heat dissipation.
There are three ways of heat conduction, convection, conduction and radiation. In a closed environment, convection and conduction are less likely to be achieved, and the emission of heat by radiation is the focus of fluorescent tube considerations. The following is the test data of our LED fluorescent tube. The temperature measured outside the LED silver foot solder joint is only 58 degrees.

The above data is a test report with an input power of 11.2 watts and a luminous flux of 890 LM. The maximum temperature inside the tube is 40.213 degrees. This temperature allows the capacitor of the power supply to work for a long time, thus ensuring the long life of the power supply!

Four security

Safety, here mainly refers to PC flame retardant plastic tube, because infrared heat can penetrate PC tube, we design to consider the safety of LED light when using it, use physical insulation of plastic, even if it is used The isolated power supply also guarantees the safety of use.

The development of LED fluorescent lamps has been going on for quite a long time. From the perspective of energy saving, its future application is quite broad. In addition to energy saving, its safe and long-life use is something we should pay more attention to!

Safety! In the design of LED fluorescent lamps, it is the first element. Using fluorescent lamps made of PC flame retardant materials, how to improve the life after solving the safety problem, the solutions proposed by the above projects hope to provide more LED fluorescent tube manufacturers. Way of thinking! (Wen Yong, general manager of Wen/Hong Baohong Electronics Co., Ltd.)