Five starting points for developing LED lighting technology

　　Five starting points for developing LED lighting technology

　　LED lamps are currently the most energy-saving, green and environmentally friendly electric light sources, and naturally become the main option for lighting energy conservation and emission reduction. As the cost and price of LED lamps gradually decrease, their popularity is also accelerating.

　　Reducing the cost of LED lights

　　LED chips account for a major part of the cost of LED lamps, so the main way to reduce the cost of LEDs is to reduce the cost of LED chips.

　　The key to the development of LED chip technology lies in the substrate material and epitaxial growth technology. The substrate material has evolved from traditional sapphire materials, silicon and silicon carbide to new materials such as zinc oxide and gallium nitride. In just a few years, with the help of a series of technical improvements including chip structure, surface roughening treatment and multi-quantum well structure design, LED has achieved a huge breakthrough in light efficiency.

　　The cost of silicon substrates is very low and the technology is constantly improving, but the current luminous efficiency is still unsatisfactory. If this development speed is maintained, once a higher level is reached, silicon substrates will become the most important technical solution and become an inevitable choice, and companies will also reap huge economic returns.

　　Improve the light efficiency of LED lights

　　Improving the light efficiency can also start from increasing the proportion of effective light. Thin-film chip technology can reduce the light output loss on each side, and use the reflective surface at the bottom to make more than 97% of the light output from the front, so that most of the light converted from electrical energy is effective light, which not only significantly improves the light efficiency of LEDs, but also creates excellent and convenient conditions for lens design. Thin-film chip technology is the core technology in the current production of ultra-bright LED chips.

　　Improve the color rendering of LED lights

　　In high-brightness white LEDs, a small portion of the blue light has a longer wavelength after Stokes shift. This is a good thing, because it allows LED lamp manufacturers to use many different colors of phosphor layers, thereby expanding the emission spectrum and effectively improving the color rendering index (CRI) of the LED. The high CRI obtained by using phosphor white LEDs comes at a cost, because the Stokes shift causes the efficiency of white LEDs to be lower than that of monochrome LEDs. However, for most lighting applications, it is better to use LED lamps with high CRI but slightly lower efficiency.

　　Improving the efficiency of LED lamp power supplies

　　Whether it is a current-limiting constant current controlled power supply or a constant current power supply controlled by an op amp, the power supply problem must be solved. That is, when the switching power supply chip is working, a relatively stable DC voltage is needed to power the chip, and the working current of the chip ranges from one MA to several MA. Like FSD200, NCP1012, and HV9910, this type of chip is high-voltage self-fed, which is convenient to use, but the high-voltage feeding causes the heat of the IC to rise, because the IC has to withstand about 300V DC. As long as there is a little current, even one MA, there will be 0.3 watts of damage. Generally, the LED power supply is only about ten watts, and the loss of a few watts can reduce the efficiency of the power supply by several points. A typical example is QX9910, which uses a resistor to pull down to get power. In this way, the loss is on the resistor, and it will lose about a few watts. There is also magnetic coupling, which is to use a transformer to add a winding to the main power coil, just like the auxiliary winding of the flyback power supply, so as to avoid the loss of these few watts of power. This is one of the reasons why a transformer is used when the power supply is not isolated, in order to avoid the loss of a few tenths of a watt of power and increase the efficiency by a few points.

　　Improving LED lighting system reliability

　　The overall efficiency, service life and reliability of LEDs must be improved through system optimization.

　　Light source: compact, efficient, choose the right color and output power.

　　Control and drive: Use electronic circuits to achieve constant current drive and control of LEDs.

　　Thermal management: To achieve a longer service life, the LED node temperature must be controlled. Heat dissipation model calculation and the use of new materials and new processes are hot spots in LED lighting technology.

　　Optical components: Lenses, reflectors or light guide materials focus light on a target area or disperse it around, depending on the design requirements.

　　With the rapid development of LED technology and the gradual improvement of LED light efficiency, the application of LED lights will become more and more extensive. Especially with the increasingly serious global energy shortage problem, LED lights will be the inevitable choice to replace incandescent lamps, tungsten filament lamps and fluorescent lamps. In addition, in terms of indoor lighting design, LED will tend to be intelligent, diversified and artistic.