LED street lighting: safety and comfort is the first demandon February 28th, 2012 at 2:04 AM
According to the insiders, LED road lighting after several years of exploration and development, the application process of accumulation of technology and product improvement, at present the market continued steady growth, its development opportunity to show. In the eighth session of the China International Semiconductor Lighting Forum” LED road lighting market and technology applications” summit, many technical experts, corporate executives gathered, separately from the use of the environment, optimization design, the feelings of consumers and how the LED light source for scientific evaluation and other aspects of how LED better application in road lighting, how to get more secure, more comfortable road lighting environment. From which we can feel LED road lighting technology and product application to more in-depth, more humane direction of a big step forward.
Taiwan Industrial Technology Research Institute of optoelectronic optoelectronic components and system application group leader Zhu catechumens
Optimization design, satisfy the human comfort requirements
LED road lighting road lighting products need to follow the relevant technical specifications, to meet the ground irradiance and regional brightness and other related requirements. LED manufacturer is concerned with the output efficiency of light, but for the users, the ultimate concern is the human eye under specific circumstances to feel the quality of lighting, the light efficiency and light quality exists between a conversion coefficient, the coefficient is related to the environment, so the road lighting products before installation need to do a lot of specific research work, can’t take a standard everywhere use.
LED lighting products should be in a deep understanding of LED light source based on physical properties and the needs of the users are highly combined, such as human sensation of light combination, with the use of the combination of environmental, develop truly humanized lighting products, and reasonable optical design is a important aspect.
Several commonly used optical design methods are: ( 1) using the structure adjustment of light, is light monomer into array, the lamp panel tilting device, in order to adjust the required light distribution. The optical design of the biggest advantage is low cost, but to meet the higher light quality is not easy to achieve, but also can do single between each different tilts, make overlay the light meets the needs of street lamps. ( 2) with the two optical design, the use of a single in vitro optical design elements, such as the reflector or lens, so that the beam reaches the desired light distribution. It can bring monomer standardization, has high flexibility, can be LED monomer and optical design separately, makes the design more flexible, to meet the different requirements of the road environment. ( 3) using an optical element, in the LED monomer directly with package lens oriented single output light type into the desired distribution form, this kind of design can reduce the inconvenience in structure design. In the road direction on the asymmetric distribution of available light plate tilt or light lens design to achieve, so can simplify the integration, but the cost of design and manufacture cost is high. ( 4) using optical device, found only in the patent, but the product is not used, the design method of optical loss and is easy to repair, can meet the high optical quality requirements. The future road lighting requires the integration of these technologies, but also into the command and control technology and network management technology.
Philips ( China ) Investment Limited company Philips Shanghai academy lighting system and application of senior fellow Zhu Xiaoyan
Investigation shows that 3000K warm white LED lights more comfortable
Talking about the LED road lighting challenges, we will usually refer to product quality challenges, such as life, reliability, failure and the investment rate of return. But the product is for lighting services, the end user is concerned there is no glare, sidewalks, is it right? Too dark, white is comfortable, whether the illumination is higher. Energy saving is not only the product itself, energy saving, more important is the application effect of energy saving, is based on the safe and comfortable lighting environment on the basis of a comprehensive consideration of index.
Road lighting to road safety services, first of all need to meet the basic needs of security.
Safety is related to visual function, visual function relates to reaction time, detection rate, disability glare ( TI ) and face recognition and other factors. Also need further consideration of comfort, visual comfort relates to color temperature, average brightness / illuminance, luminance (illuminance ) uniformity, glare, environmental factors such as.
Philips do a lot about LED road lighting visual comfort research, such as the Holland Apeldoorm LED street lights sensory evaluation experiments, in the French city of Lyon do outdoor warm white lighting effects for the user sensory evaluation test, in China Suzhou outdoor warm white lighting effects for the user sensory evaluation test, in Shanghai to do the color temperature of road lighting discomfort glare effect.
According to the survey feedback, LED street lighting can be positive to accept, because the LED is energy saving, sustainable development source, LED will be looking to improve lighting on visual and sense of security, with innovative design of new products are always welcome. In general, when the streets and sidewalks road surface illuminance illuminance contrast is small, lighting and effects is very easy to be positive recognition; in general, warm tone LED was found to be comfortable. Of course, LED road lighting also faced some criticism: such as lighting is too bright, severity of glare, light is very bright, can interfere with vision and line of sight.
The experimental results show that, warm white ( 3000K ) than the cool white ( 6500K ) discomfort glare is smaller, more comfortable. LED road lighting warm white light is preferred, but it is not enough to consider. The sidewalk and driveway low contrast is more popular, the sidewalk minimum acceptable illumination range > 1.3Lux, most acceptable brightness contrast is 40% ~ 50%, sidewalks and building facade lighting degree directly affects people’s sense of security and comfort. Therefore, for road lighting, improve the sidewalk and driveway illuminance ratio is very important.
The related literature and case shows, fluorescent color of the metal halide lamp for road lighting in visual sensation on mechanical cold, no warm white light feel good, no HPS ( HPS ) gold good in color; white light far, eye observation ability, not suitable for hyperopia, hyperopic best with warm white light; suitable for road lighting color should be HPS light golden yellow light or warm white light; you light, fluorescent color LED street lamp is not suitable.
Therefore, through the experiment and theoretical study of feedback can be found, for the LED road lighting light color, cool white is market expedient option, while warm white is the LED road lighting in the correct direction. With warm white light technology, LED will better solve the contradiction between comfort and energy saving.
PhilipsLumileds lighting company Asia Marketing Director Zhou Xuejun
LED road lighting market opportunity to show
In 2011 last year and last year, LED street lamp lighting market presents stable development state and trend, on one hand the industry for the road lighting market expectations not so high, for the demand forecast to more rational attitude regression. On the other hand, through the first years of application and exploration, LED road lighting products continued to mature, cost drops continuously, make LED street lamp lighting market development opportunity to show.
From the LED street lamp market development the factor analysis, the current conservative, chip prices every 3 months decreased by about 5% or so, the whole system cost recovery cycle to 3 ~ 4 years approximation, falling prices for market start is important, although the future of the central government is unlikely to have the road lighting introduced very significant subsidy policy. In addition, in the EMC business model, because most of domestic investment companies require a higher rate of return on investment return period is too long, often become the EMC mode to carry out main factors. But with the overseas funds to enter, the rates of return on investment requirements are relatively low, the investment return period is shortened the case, those who have foreign capital background of EMC company active.
Furthermore, the 2012 LED street lamp output is expected to account for the entire street market in 50%, and in the market to promote respect local governments play a very important role in the three or four line of the city, more often than a city more active. With earlier around the street management relatively conservative attitude is different, at present, part of the street lamp management departments have started to try the scale of the use of LED road lighting products. Finally, the city changes a course accelerate also can stimulate the LED road lighting demand.
And tunnel lighting market to start earlier, has formed a stable market pattern is different, LED street lamp market national brand is not much, mostly regional brands, therefore, the enterprise still has certain development space. At present, many LED street lamp enterprises have begun to pay more and more attention to the standard application, light quality and visual comfort and more humanized lighting demand factors.