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  • 新闻名称: White LED interior lighting applications
  • 发布时间: 2014-02-18

As a light source with great development potential, LED long life, firm structure, the advantages of lower power consumption and flexibility of dimensions has been more and more attention in recent years, LED particularly monochromatic LED is widely applied in the big-screen, traffic lights, landscape lighting. With the development of LED technology, white LED light effects, color rendering, color temperature, and a single LED indicators for power and luminous flux of LED modules and other parameters can make new breakthroughs, people apply LED lighting full of expectations.
However, white light LED applied to normal indoor lighting is also facing a series of challenges, such as single LED lighting flux is difficult to meet the needs of general lighting, high unit costs, low luminous efficiency than energy-saving lamps, chromatic aberration, lack of stability, and so on. Although the research situation is gratifying, but producing market-oriented products that truly meet the lighting requirements still need to be a certain amount of time, it's LED developers, producers and users it doesn't shy away from the truth. Lighting and ergonomics, and analysis of the current development status of the white-light LED light environment and health differences between the normal indicators that you need, to the process of promoting the application of LED lighting in the room made a number of recommendations:
1, lighting ergonomics
Ergonomics ergonomics/ergonomics, with "man-machine-environment" systems for the study, the use of methods such as observation, statistics, analysis, and research "man-machine-environment" relationship between the three major elements of the system in order to settle the effectiveness of the system, health problems. In other words, design and ergonomics of the study is to human needs, human capacity, the limit, and the coordination of tasks, jobs, products, environments and systems. Lighting ergonomics is a study of lighting environment designed to meet people's needs, make it faster and better through each Visual work or try to meet demand for comfortable and healthy.
Lighting should take full account of the environment meet the needs of Visual functions, enabling people to work properly in an appropriate visual environment, that is able to see clearly; and meet the psychological needs, that is, to read more comfortably. A recent study showed that light can also affect the secretion of melatonin in the body and affect the body's circadian rhythms, and health. Therefore, should consider good ergonomics of lighting environment human visual, mental and physical needs, consider a number of factors, or it can have on people's productivity, adversely affect the mental or physical health.
2, taking into account the requirements of ergonomics to white LED lighting
As previously stated, ergonomics should be taken into account in considering lighting requirements for lighting environment. Indoor environment is the environment people live and work most of the time, so people's demand for indoor lighting environment is getting higher and higher. Ability to meet these requirements, is the key to LED indoor lighting instead of the traditional light source.
2.1 Visual functionality requirements
In order to meet people's Visual needs, that is, to allow people to see clearly, that required lighting luminous environment with a certain level of illuminance, uniformity of illuminance and color rendering.
To meet certain levels of illumination, requires the LED luminous enough. In the case of a small reading room, assuming the reading room area of 6mx8m, about 20000~30000lm luminous flux in order to meet the reading needs of normal people. If they do not take into account other factors, 200lm of high-power particle on the market today also takes 100~150 particles LED to reach the requirements for illumination. Due to better market efficiency at around 30~40lm/W, regardless of energy consumption or costs, LED not to compete with energy-saving lamps or fluorescent. In addition, the immature in optical design of LED lighting technologies make the current LED lamp light distribution is not stable enough, they must reach a certain uniformity of illuminance at a high cost. But for the small area of accent lighting, LED can meet the needs of Visual, with a small amount of power consumption, in terms of uniformity could be more easily met. And in terms of color, the current white-light LED can meet the basic needs of indoor activities.
2.2 psychological needs
In normal indoor work or activities, people will not only require Visual function meets, also requires a certain degree of visual comfort, this is the people's psychological needs for lighting luminous environment also required light environment is not within the field of view has a direct or indirect glare flare, color temperature, lighting layout to appropriate and comfortable. In terms of requirements will vary depending on the glare, white LED light is both a strength and a challenge. Because of the LED beam angle and smaller dots, light emitted is very easy to control, but on the other hand, LED light intensity is usually set at maximum light intensity distribution if not handled properly can easily cause glare to the observer. Studies have shown that discomfort glare not only can cause a decline in productivity, but also can cause eye strain and headaches and other adverse reactions. In addition, the selection of three-chip RGB LED, are able to form any colour temperature white light, but larger color differences will affect the field of view of comfort and overall appearance. If you use blue light LED plus YAG powder, color temperature too high. In order to make the lighting with good effect, select the color temperature of the light source must be appropriate to require illumination, as shown in Figure 1 is the illuminance and color temperature corresponds to the comfort zone. Therefore, a higher color temperature can also affect the application of white LED in indoor lighting, because it requires a corresponding high level of illumination, to make people feel comfortable. The other hand, LED flexible form factor that LED lamps are designed with a lot of space that can fully meet the requirements of decorative.
2.3 the physiological needs
Interior lighting on physiological needs mainly for health needs. In addition to long-term UV exposure will have an adverse impact on the skin, affecting the health of the other two ways are often overlooked by people, one is through the Visual impact on health, and the other is through the circadian system affects health. Close contact with white LED interior lighting two Blu-ray is retinal hazard effects of light suppress melatonin secretion in human body the human circadian system and health. Typically ultraviolet light damage occurred in the eye before parts of the human eye, corneal damage. Blue light has wavelengths longer than ultraviolet light, through the eyes can reach the retina; and in the per unit of energy in the range of visible light is strongest, easily burn the retina and early cataracts. Meanwhile, melatonin secretion in the body under the influence of light, when melatonin secretion disorders, easily lead to confusion of the body's circadian rhythms, which causes cancer or other diseases.
In the 400~500nm region, this white light LED energy distribution with an apparent peak. Add a certain amount of Red phosphors can to a certain extent reduce the peak, but now predominantly white light LED using the Blu-ray region peak retinal hazard spectral sensitivity curve with Blu-ray and ganglion cells to light affecting circadian system's sensitivity curves have more overlapping regions, which had to be brought to our attention. When you use a UV LED plus three color phosphors for white light and RGB MultiChip LED, both of these effects can be ignored.
3, the status quo of white light LED
3.1 light effect
LED since the last century since the birth of the 60 's, to brightness up to 30 times times every 10 years, prices down 10 times "law of hydes"-like pace. It was reported that the current White LED luminous efficiency of laboratory data of over 100lm/W, and entering into the commercial field of high-power white LED light also reached 40lm/W. With the breakthrough, high-power LED luminous efficiency of the future still has a lot of upside, is likely to reach the highest 150~200lm/W.
3.2 luminous flux
With the launch of high-power LED and breakthroughs in key technologies such as packaging, thermal, 5WLED of the commercialization process has begun to take shape, the luminous flux of LED modules to be greatly improved. From Japan Asia current research data indicate that power and 5.5W respectively, flux and 250lm respectively integrated high-power LED module has been developed. LED for general lighting and this process has taken a major step forward.
3.3 color temperature and color rendering index
LED color temperature and color rendering properties of white light and white light LED is closely related to the preparation of programme. In 1996, Nichia Corporation, first using InGaN blue light chip plus YAG (yttrium aluminum Garnet) $ phosphors made from white light LED. Since then, people using r, g, and b color chips mixed light and near-ultraviolet chip stimulates the r, g, b tri-color phosphors for white light LED light made from the mixing.
Blue light LED plus YAG phosphor process simpler, lower technology costs, is currently the most common way of preparation of white light LED, but its relatively low color rendering index. Add some red phosphor and green phosphors can improve color rendering index, but because of the lower red light phosphor conversion rate, total luminous flux attenuation typically occur, namely efficiency decline. A near UV LED plus RGB phosphor powder, in theory you can get any higher color temperature and color rendering index white light LED, but now used for UV LED Phosphor technology has not yet matured. Method of single-chip coated phosphor based on phosphor coating technology of different, often have differences in color temperature 80~800K. Multi-chip LED it is theoretically possible to get any color temperature and high color rendering properties of white LED, but because of MultiChip LED forward voltage and different light output, maintain their temperature characteristics and optical properties are not the same, thus higher requirements for circuit design, the current technology is not yet mature, module secondary colour temperature varies.
4, promoting the application of white LED in indoor lighting
High-power white LED light effect, color and made great breakthrough single power, rapid momentum LED manufacturers to constantly update the achievements already made. However, in terms of taking into account ergonomics, to create an environment consistent with the Habitat needs of lighting, LED obviously still has a long way to go. In order to promote LED more and more rationally applied to interior lighting, following several aspects of LED designers, producers and users should be of mutual interest.
4.1 emphasis on reasonable lighting design
As far as Visual functions need, current LED luminous flux and luminous efficiency is also struggling to meet the needs of large area for general lighting. Thus, the reasonable lighting design is the key to LED in indoor lighting. For example, you can use local LED accent lighting or using auxiliary lighting and the LED is easy to control this feature adjusts the light design. Design should be combined with Visual functional, psychological and physiological needs, weaknesses, creating a healthy and comfortable environment.
4.2 strengthen LED secondary optics design technology
Is a key technology for LED lighting applications LED secondary optics design technology, through secondary optical design, LED light distribution optimization, while avoiding glare LED lights that had been shot better, meet the requirements for lighting.
4.3 attention LED upper, middle and lower reaches of the close contact
There is no doubt that LED from the upper and middle reaches of the development and application of LED technology has a key role, but the demand for downstream applications, and also plays a leading role in the middle on the LED. Scientists, engineers, and designers should strengthen contact, LED industry more streamlined and user-friendly.
LED interior lighting standards 4.4
Current inspection departments concerned have initiated research on the testing method for LED lighting, including test equipment development. National lighting Standardization Technical Committee has LED lighting standards technical standards and test methods included in the standardized work plans, hope through LED-lit standard development, promote the development of LED technology and lighting applications. LED indoor lighting standards should focus on optical characteristics of LED, distribution of the luminous flux, light, brightness, spectral distribution, chromaticity coordinates, color, color rendering index, lumen maintenance and so on. In addition, electrical accessories, mechanical properties, temperature characteristics and range of appliances should also be taken into consideration, such as security features.
5, concluding remarks
White LED in indoor lighting in the process has made significant breakthroughs in the last two years, taking into account the lighting on the basis of ergonomics, white LED in indoor lighting has certain advantages, however, still has many shortcomings. LED Designer, producers and users should unite the common building blocks for the development of LED technology, getting the most out of the next-generation light sources as soon as possible, get more benefits.