LED lighting market opportunities for the industry to bring infinite imaginary space, LED lighting applications have outdoor LED to jump from the past to the indoor lighting applications. According to the STrategies Unlimited statistics, over the next five years the development of LED indoor lighting will have exponential growth trend. In 2011, according to estimates, the output will be up to tens of billions of dollars. Especially take the lead in implementing the eu in 2009 banned incandescent lamp, and much attention has been paid to energy conservation issues, has produced the LED indoor lighting the huge market opportunities and optimistic outlook. Below from the cooling technology, optical design and driver design such as lamps and lanterns of demand, analysis of high power LED development in the field of indoor lighting.
The development of high power LED lighting of high power LED lighting development depends on two elements: one is the chip itself. 2 it is technology of lamps and lanterns, including thermal, optical, driver.
The chip support
At present, the key to the development of the LED chip technology is the base material and the technology of epitaxial growth.Basal materials from the traditional material, silicon and silicon carbide, sapphire to zinc oxide, new materials such as gallium nitride.Whether for accent lighting and integral illume high power chip, is used for decorative lighting and some simple auxiliary lighting low-power chips, technology upgrade key is about how to develop more efficient, more stable chips.In just a few years, with the aid of including chip structure, surface roughening treatment and multiple quantum well structure design of a series of technical improvement, achieved great breakthrough in the field of photosynthetic efficiency of LED.Figure 1 is the development of LED chip structure diagram.With the gradually mature of production technology, LED quantum efficiency will increase further, the LED chip of photosynthetic efficiency will be enhanced.
Thin film chip technology is the core technology of the ultra bright LED chip production, to reduce the loss of the light output of each side and can use at the bottom of the reflector makes more than 97% of the light output from the front (see figure 2).This not only significantly improve the LED lights, but also created a favorable conveniences for lens design.
Lamps and lanterns technology needs
1. Heat dissipation technology
The public has been paying attention to the service life of lamps and lanterns.If just rely on a low thermal resistance of LED components for the installation of lamps and lanterns is not a good cooling system, and must effectively reduce the thermal resistance from the PN node into the surrounding environment, to reduce the PN node temperature of the LED, prolong the service life of LED lamps and lanterns and successful practice and improve the actual flux goals.Different from the conventional lamps and lanterns, printed circuit board is LED power carrier, is also LED the heat carrier, so the heat dissipation fin and printed circuit board design is very important.In addition, the lamps and lanterns manufacturers must also consider the quality of the heat dissipation material, thickness, size and heat dissipation factors such as the processing of interface and connection.
2. Optical design
Compared with traditional lamps and lanterns, directional and point lights is the most typical two characteristics of LED, and how to make use of the two characteristics of the LED is the key of the optical design of lamps and lanterns.
Through the binary optical design of LED, LED lamps and lanterns can achieve better light distribution curve.For example, in the applications of indoor lighting lamps and lanterns light need to be very bright, can use a high light transmittance chimney improve the light extraction efficiency.Or applied technologies of light guide plate to lamps and lanterns, so as to change the LED point light source for the surface light source, not only can improve the light distribution uniformity of lamps and lanterns, also can prevent glare.In addition, in some auxiliary lighting and accent lighting applications, in order to highlight to illuminate objects and need specific focusing effect, in this case, it can be used with some projection lens and reflector, in order to achieve the ideal optical effect.
3. Driven design
Must ensure that the LED drive current to constant current output.When the LED is electrical work flow, relative changes in node voltage is very small.Therefore, to ensure a constant LED drive current, basically equal to ensure constant LED output current.In addition, lighting control design is one of the mainstream driven design, more atmosphere for lighting applications, according to the different environment to realize the different brightness levels, can fully realize the goal of energy saving.At present, the main trend of the driven design focuses on improving power factor, reduce the power consumption of the drive, optimizing the control precision and speed up the response.In the design process, the design of power supply, the layout of the printed circuit board and series-parallel ways are all factors must be considered.
High power LED lighting technology challenge
Even LED in indoor accent lighting and decorative lighting applications have satisfactory performance, but in general lighting and atmosphere lighting applications are still facing many challenges, including the initial cost, low color temperature of light, color rendering index and system reliability, etc.
1. At the beginning of further reduce the cost
Cost is a relatively sensitive factor in indoor lighting, especially in household lighting applications.Although leds model more and more, photosynthetic efficiency has been improved, but the price is high the problem still exists.But when the price of LED light source is reduced, the overall system design optimization, the total cost will decline.Recall the compact energy-saving fluorescent lamp on the market for the first time, costs about $15, has dropped to below $1.50.Can be concluded that, therefore, with the continuous development of the market, and the price of LED lights will soon to acceptable levels.
2. Improve low temperature of photosynthetic efficiency
Low colour temperature below 4000 K is usually the first choice for indoor home lighting. Warm Bai Guangling whole environment more warm and relaxed; And cold Bai Guangze clean, efficient and bright feeling to the person, more suitable for office and outdoor lighting. Because phosphor powder, when low color temperature of LED lights usually about 30% lower than the high colour temperature.
3. Management of photosynthetic efficiency and color rendering index
In general, the higher the leds luminous efficacy and color rendering index is lower. Indoor lighting usually require LED has higher color rendering index, in order to objectively display brightness and color of the object and to the naked eye directly observe the actual effect of the external landscape. Therefore, improve the LED lights at the same time, also need to further improve the color rendering index. Another method is to add some red light in the surface of lamps and lanterns, so as to achieve the effect of color rendering index more than 90.
4. During high current drive efficiency
Currently, usually 1 w LED current can be increased from 350 mA to 1000 mA.Under high current drive, however, even if the flux increased, the overall efficiency is usually relatively significant decline.Therefore, must be the total cost and balancing system photosynthetic efficiency.If we can improve the LED lights, under high current drive is just make sure to provide higher light efficiency of the system, can greatly reduce the required number of leds, so as to reduce the production cost greatly.
5. To further narrow the LED packaging size
In addition to environmental protection, energy saving, pollution-free, indoor also LED to personality these artistic quality, small size and characteristics.And through the narrowed LED packaging size, can make the lamps and lanterns design flexibility and the innovation space.To need to use mixed lighting applications in order to improve the color rendering, smaller packaging size helps to realize hybrid optical lens and the lighting design.
6. To extend the service life, improve the system reliability
In general lighting applications, LED the overall efficiency, service life and reliability must be through the system optimization to ascend.Traditional lamps and lanterns of the assembly system is simpler, and LED lighting system involving multiple components, as shown in figure 3.
LED light source: compact, high efficiency, has a variety of colors and the output power to choose from.
Power conversion: converts alternating current (ac), batteries and other power efficient safe low voltage, constant current power supply.
Control and drive: use electronic circuit realization LED constant current drive and control.
Thermal management: if you want to achieve a longer service life, LED node temperature control is very important, thermal analysis is also indispensable.
Optical element: lens, reflector, or guide plate material is to focus light on the target area for the required optical element.
Used in indoor lighting of LED light source is introduced
As already noted, compact and efficient is to select the LED light source of important factor. Mr OSLON SSL LED is the latest product of osram opto semiconductors, its power is about 1 w. As shown in figure 4, the LED is mainly designed for general indoor lighting, compact appearance, package size is only 3 mm x 3 mm, and the performance is stable, reliable, luminous efficiency is remarkable, maximum photosynthetic efficiency of more than 100 lm/w. Even in high power flow, it also can maintain excellent luminous efficiency and thus effectively reduce the overall cost of lamps and lanterns. And has high reliability and 80 & deg; Beam Angle, so can be smoothly to external light projection lens. The LED spotlights or indoor lighting, desk lamp and ceiling omni ideal light source.
Because it LED to deal effectively with high current, so it can help consumers create extremely energy saving and cost saving lighting solution. In this regard, Mr OSLON SSL LED has become the future & other; Green & throughout; All the characteristics of the light source. The LED thermal resistance as low as 7 k/W, thermal management is more simple, the appearance of the cabinet is that designers can more flexibility to create complex delicate lighting solution. If you need, don’t strong light, can be used with some of the lamps and lanterns collocation. In addition to the super white light (color temperature is 5700 ~ 6500 K) version, and white light in warm white light (color temperature is 2700 ~ 4500 K) version.
Mr OSLON SSL manufactured using the latest LED chip technology, ensure the high photosynthetic efficiency. Mr OSLON SSL LED the main parameters as shown in table 1. At present, when working current is 350 ma, the light source of super white light (color temperature of 5700 K and 6500 K) typical brightness as high as 110 lm, luminous flux maximum reach 130 lm. When working current is 350 ma and color temperature is 3000 K, the typical photosynthetic efficiency can reach 75 lm/W, brightness, 85 lm. When working current is 700 ma (warm white), brightness 155 lm, can reduce the unit cost of lumen, also can maintain high photosynthetic efficiency, even a small amount of leds can also achieve high standards of lighting.
For example, only need seven Mr OSLON SSL LED, can design a about 15 w LED spotlight (see figure 5). When the drive current of 700 ma, the brightness of the leds can reach 1400 lm, and size is very small. Depends on its 80 & deg; Beam Angle, carrying reflector or lens, light efficiency is still very high. Even after taking into account heat dissipation and optical loss, lamps and lanterns of the final flux can be more than 1000 lm. In addition, when you need different color temperature and color rendering index, only a minority of the seven star LED shall be replaced as warm white or other monochromatic LED Mr OSLON SSL.In this way, can get any or higher color temperature, color also greatly increase the design flexibility of LED lights.
With the rapid development of LED technology and the gradual improvement of the LED lighting, LED application will be more and more widely.With global energy shortage problem increasingly serious, in particular, people pay more and more attention to the development prospects of the LED in lighting market, the LED will be replace incandescent lamp, the potential of tungsten filament lamp and fluorescent lamp light source. In addition, in terms of interior design of lamps and lanterns, the LED will incline to energy conservation, human nature and art.And Mr OSLON SSL LED in accordance with the requirements of the indoor lighting application, it not only packaging size to 3 mm x 3 mm, and stable and reliable in performance.Its maximum photosynthetic efficiency of more than 100 lm/w, even in high electricity flow can maintain excellent light efficiency, and effectively reduce the overall cost of lamps and lanterns; In addition, because of its 80 & deg; The light beam Angle, so would like to outside projected onto the lens or reflector. In short, Mr OSLON SSL is indoor LED lamps and lanterns is the ideal light source.