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Application of white LED in indoor lighting

From: Data:02/08/2016

as a light source with huge development potential and advantages of LED's long life, firm structure, low power consumption and flexible dimensions by more and more people's attention, in recent years, led especially monochromatic LED is widely application in large screen, the signal lamp and the scene view lighting. With the development of LED technology, white LED luminous efficiency, luminous flux of the color, color temperature and single LED power and LED module etc. parameters continuously made new breakthroughs, the people of LED applications in lighting is full of expectations.

however, will white LED applications to ordinary indoor lighting also faces a series of challenges, such as single LED luminous flux is difficult to meet the demand for general lighting, high unit cost, light efficiency energy-saving lamp low, color, lack of stability. Although the situation is gratifying, but to produce a truly meet the requirements of the lighting market products still need a certain time, which is LED R & D personnel, manufacturers and users can not avoid the fact. The from the lighting of the body function of analysis of the current situation of the development of white LED and and differences between normal index required by the healthy environment, to promote the LED in the application process of indoor lighting, some suggestions were put forward. Human efficacy of

1, lighting illumination environment should be fully considered to meet the needs of the people of vision, so that people can work normally in a suitable visual environment, that is able to see clearly; but also to meet the psychological needs of people, that is, to see more comfortable. A recent study shows that light can affect the body's physiological rhythm and health by affecting the secretion of melatonin in the body. So consider ergonomics of good luminous environment should starting from the visual, psychological and physiological needs, comprehensive consideration of the number of factors, otherwise it will to the people's work efficiency, physical or psychological health caused adverse effects.

2, white led the development of

2.1 light efficiency

2.2 flux

2.3 color temperature and color of

white LED color temperature and color rendering of white LED and preparation of closely related. 1996 Nichia company first used InGaN blue chip and YAG (yttrium aluminum garnet), method of fluorescent powder made of white LED. Since then, people have used R, G, B three color chip mixed light and near UV chip to stimulate the R, G, B three color phosphor mixed light made of white LED.
using the blue light LED and YAG fluorescent powder because of its simple process, low technical cost, is the most commonly used way to prepare white LED, but its color index is relatively low. Add some red light fluorescent powder and green fluorescence powder although can improve the color rendering index, but due to the red light fluorescent powder in the relatively low conversion rate, usually caused by attenuation of the luminous flux of the overall optical efficiency decline. The near ultraviolet LED and RGB trichromatic fluorescent powder theory can get any color and higher color index of white light LED, but currently used for UV LED fluorescent powder technology is not yet mature. Method of single chip is coated with fluorescent powder according to the coating technology of fluorescent powder of different color temperature difference is usually 80~800K. Multi chip LED theory can get any color and high color rendering of white LED, but due to the different multi chip led forward voltage and light output, also its properties in the temperature and maintaining the light characteristic is not the same, so higher requirements on the circuit design, the technology is not mature module Jianse temperature greatly different.

3, considering the effect of human body on the requirements of white LED lighting

as mentioned above, consider the effect of lighting should be taken into account the requirements of the lighting environment. Indoor environment is the environment that people live and work most of the time, so the demand for indoor lighting environment is more and more high. Whether it can meet these requirements is the key to LED instead of the traditional light source for indoor lighting.

3.1 visual function of demand

in order to meet people's visual needs, that is, to make people can see clearly, which requires a certain degree of illumination light environment, illumination uniformity and color rendering properties.

to meet a certain level of illumination, requires LED with sufficient luminous flux. To a small reading room, for example, assuming that the area of the reading room for 6m× 8m, is about to 20000~30000lm lumen Liangcai can satisfy the need of people's normal reading. If you do not consider other factors, the application is currently on the market 200lm large power particles also need 100~150 particles of LED to achieve such an illumination requirements. Due to the better light efficiency of the current market in 30~40lm/W or so, regardless of energy consumption or cost, LED can not compete with energy-saving lamps or fluorescent lamps. In addition, LED lamps and lanterns of the optical design technology is not mature so that the current LED lighting distribution is not stable enough, to achieve a certain degree of uniformity of illumination also requires a high cost. But for a small area of focus lighting, with a small amount of energy consumption of LED can meet the needs of vision, in terms of uniformity is also relatively easy to meet. And in the color of the color, the current white LED basic can meet the needs of the general indoor activities. <

3.2 psychology in normal indoor work or activities, people not only require visual function to meet, also need a certain degree of visual comfort, this is people to control illuminating light environment of psychological needs, demands within the field of view of the light environment can not have direct or indirect glare of glare, color temperature to appropriate, lamps and lanterns decorate to be comfortable. In terms of the requirements of the field of view of glare, the white LED is both an advantage and a challenge. Due to the smaller LED luminous point and the beam angle, so that the light a fire direction is easy to control, but on the other hand, usually led light is more concentrated, maximum intensity distribution, if not handled properly is easy to for the observer cause glare. Research shows that discomfort glare not only can cause the decline of work efficiency, but also can cause visual fatigue and headache and other adverse reactions. Also if the RGB LED chip selection, although can form any color of white light, but larger color will affect the field as a whole comfortable and beautiful. If the selection of Blu ray LED plus YAG powder, then the basic high temperature. In order to make the lighting has a good effect, the selection of light source color temperature must be and requirements of illumination to adapt, 1 is shown in illuminance and color temperature corresponding to the comfort zone. Therefore, the higher color temperatures will effect of white light LED in indoor lighting applications, because it requires a correspondingly high illumination, in order to make people feel comfortable. On the other hand, LED flexible shape and size of the LED lamps in the design of a large space, can fully meet the requirements of decorative.

3.3 physiological needs

indoor lighting in people on the physiological needs of the main performance for the health needs. In addition to the long-term UV exposure can cause adverse effects on the skin, light effect health in two ways is often neglected by people. A is light through visual impact health and the other one is the optical influence of the circadian system health. With the white LED used for indoor lighting close contact of the two effects is the retina of blue light hazard effect and light through inhibit the body in melatonin secretion and affect the body's circadian system and health. UV damage usually occurs in the front part of the human eye, that is, damage to the cornea. Blue light, because of its longer wavelength than ultraviolet light, can reach the retina through the fundus, and its unit energy in the visible range of the strongest, easy to burn the retina and the formation of early cataract. On the other hand, the secretion of melatonin in the human body is affected by the light, and it is easy to cause the disorder of the human body's physiological rhythm when the melatonin secretion is abnormal, which causes cancer or other diseases.

in the region of 400~500nm, the energy distribution of this white light LED has an obvious peak. After adding a certain amount of red light fluorescent powder can reduce the peak in a certain extent, but the current widespread use of white led the blue region peak and blue retinal damage spectra sensitivity curve and its influence of the circadian system of ganglion cells to light sensitivity curve more overlap region, which had caused our attention. And if the use of UV LED plus three color phosphors and RGB multi chip white LED, these two effects can be ignored.
4, promote white LED in indoor lighting application

4.1 attention and reasonable lighting design

4.2 attention led, midstream and downstream closely

there is no doubt, led midstream of LED technology development and application of played a key role, but downstream applications and demand also led the upper and middle reaches to leading role. Research workers, engineers and designers should strengthen the contact, so that the development of the LED industry is more reasonable and humane. One of the key technologies in the

4.3 LED two optical design technology LED

lighting applications is the LED two optical design technology, which can optimize the distribution of the light distribution of LED through the two optical design.