1、 Product development direction
The light efficiency of LED has obviously exceeded that of compact fluorescent lamp. Due to the directionality of LED light, good light distribution can be achieved almost without using reflector, that is, the efficiency of lamp can reach about 90%, which is the advantage of LED lighting.
As a novel solid light source, LED has many unique advantages, such as almost no pollution in the production process and products, no fear of vibration, continuous dimming of 0% ~ 100%, working under ultra-low voltage, continuous working in the working state of switch and flash off, and directional output light. In recent years, the obvious progress in its light efficiency and light color has enabled it to enter commercial application, However, in the design and use, we must pay full attention to the characteristics of LED and make full use of its strengths and avoid weaknesses in order to achieve the expected good results.
At present, in the application of LED, we should give full play to its function of directional light output, make use of the specific beam output angle and different light intensity output of single LED, the reasonable design of installation direction and the function of lamp reflector to realize three-time light distribution, and make full use of the direct light and directivity of led to maintain the full utilization of LED emitted light and the uniformity of lighting, so as to prevent excessive lighting in local areas, Make up for the deficiency of its own luminous efficiency, so that the system efficiency can be significantly improved. At present, there are still many gaps in the efficiency level and output light intensity level of LED as a commercial application.
In addition, the road lighting lamps using LED as the light source shall be designed to ensure the reliability and continuous effectiveness of heat dissipation on the premise of IP protection. The LED driving circuit shall have high efficiency and perfect protection characteristics of EMI and EMS. The LED lamps with these characteristics not only have good lighting power density (LPD) index, but also have the advantage of no stroboscopic output light, which is very beneficial to the lighting of moving objects.
2、 Main problems of LED in lighting application
(1) Luminous flux needs to be further improved. There is still a big gap between the luminous efficiency of LED and high intensity gas discharge lamp (HID). Using LED as the lighting source must be able to emit more light and have higher energy conversion efficiency. At present, countries all over the world have stepped up the research on improving the luminous efficiency of LED.
(2) There is still a certain gap between the light emitted by LED and natural light. Natural light has a very strong yellow spectral component, giving people a warm feeling; The white light emitted by white LED has more blue light components. Under the illumination of this light, people’s vision is very unnatural.
(3) The price is high, which is the main reason affecting the popularity of LED lighting. However, in recent years, with the improvement of LED chip production technology and the lifting of the ban of various patented technologies, the manufacturing cost is declining sharply. LED lighting lamps are developing towards high efficiency and low cost, which provides favorable conditions for the wide application of LED in the field of lighting.
(4) The combination of electric light source technology and microelectronics technology is not enough, the control mode is monotonous, and the control means are primitive LED manufacturers should pay attention to the application of microelectronic technology in the field of light source control. They can learn from the practice of large outdoor LED display screen, control the luminous gray of dry LED light-emitting unit according to the duty cycle, and adopt embedded microcontroller to realize independent digital control.
(5) The consistency and reliability of products need to be improved. Since lighting fixtures need to be composed of multiple LED monomers, the parameter discreteness is an important technical problem. In addition to ensuring consistency as much as possible through pre selection and classification, it is also necessary to design reasonable lamp structure (including the arrangement and position layout of LED monomers) and study appropriate driving circuit to prevent accidental energy concentration from damaging some LEDs. In addition, when multiple LED monomers form a lighting lamp, it is inevitable to connect and apply the LEDs in parallel. In the process of use, as long as one LED is short circuited or open circuited (mainly open circuited), Will lead to the change of the working point of a small piece or the whole LED, shorten the service life or extinguish, and affect the lighting effect. Therefore, we must study a simple, cheap and effective protection circuit to minimize this adverse effect.
3、 Problems to be solved in the research and development of LED lighting products
LED is the most promising high-tech lighting source in the 21st century. As a new type of high-efficiency solid-state light source, LED has significant advantages such as long service life, energy saving and environmental protection. It will be another leap in the history of human lighting after incandescent lamp, fluorescent lamp and high-pressure gas discharge lamp. A relatively complete industrial chain has been initially formed in the production of epitaxial wafer, chip manufacturing, device packaging and integrated application of semiconductor lighting products, However, there are many restrictive factors in the realization of LED functional lighting. Therefore, in the current situation, we place the following hopes on the development and design of LED lighting products
(1) Meet people’s personalized needs for lighting. The modularization of LED brings convenience to the lighting design. Through the full and reasonable layout in the design, the LED is in good working condition LED lighting products are dwarfed by traditional light sources in meeting personalized lighting, and the shape diversification of LED lighting products will reach an unprecedented level. Therefore, the personalized R & D and design of LED lighting products is the biggest challenge that all LED lamp manufacturers must face.
(2) Environmental protection, energy conservation and rational utilization of LED, the concept of green lighting is the ecological design goal followed by the world. The optimized design of scenery complementary LED street lamps will expand the application scope and places of LED.
(3) Research and development of white LED lighting products with high power, high luminous efficiency and commercial color rendering. At present, the use of LED in the lighting field is still limited by the technical level and price. At present, the difficulty in the application of LED in the lighting field is that the light efficiency, power and price of white LED are not high. However, the development prospect of white LED is promising. The luminous efficiency will reach 1001m / W and the output power of a single LED will reach 10W. The research on the integrated packaging technology of high-power and high brightness LED, including the development of driving circuit and special lamps, is undoubtedly the key for led to finally enter the lighting field. Once the problems of light efficiency and price are solved, LED will be the main body of lighting in the future.
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