Wednesday, January 5, 2011
【 Weak current College 】 LED lighting development five Aeras 】
The most suitable LED lighting color temperature range should be close to the Sun natural white colour temperature range is the most scientific of choice; low irradiation intensity of natural white light, you can reach other non-natural white incomparable radiation effects; the most economical surface brightness range should 2cd/m2; improving lighting total uniformity and eliminate glare is the energy consumption of the most effective way.
In incandescent lamps, high pressure sodium lamp, the lighting of color have no choice but to quietly accept and adapt. However, you can select the color temperature to the LED lighting times, select what kind of LED lighting color temperature, becomes an urgent need of it with a clear conscious perception of the problem. This is related to energy efficiency and lighting quality event, we should not tolerate sloppy.
There is a saying that tend to move with European hobby, select 2700-3200K color temperature range. It is said that this is the European preference in color temperature range. On this, I have a different point of view, move to discuss with you:
1. identification of the human brain on things and response mechanisms
The human brain through the eye to get outside things with images of the first reaction is to the image and the original storage in the brain and memory compared to the image information in the body on which recognition, then immediately make the appropriate response actions. If you get image information and original storage information closer to identifying the faster, more agile response to. Driver's night if the difference in natural light during the day and further low color temperature light, to obtain the recognition of images, the more difficult to identify the slower speed, response speed slower followed. Answer slowed 0.1 seconds the result is sufficient to let the accident rate suddenly spurt. To compensate for the difference between day and nightillumination lighting defects arising from, the only solution is to increase the lighting intensity to improve in the low speed of recognition under the color temperature, this means that the increase in energy consumption.
From animals to humans of hundreds of thousands of years of a long process, human beings have always been living under the Sun of natural light, are all production and social activities. Long natural selection and evolution of the results, making the most of human eyes adjust color temperature range is Sun natural white colour temperature range (5500-7500K). Human eyes in this color temperature, dynamic and static object identification most powerful; in this color temperature range, the human response to external things also most agile. Because the people inside the brain and memory information stored in the object image information, mostly in natural white light exposure. Therefore, the most appropriate LED lighting of color temperature range should be close to the Sun natural white colour temperature range, is the most scientific of choice.
2, Europeans like low color temperature of the biological, geographical reasons
Then, why Europeans like low color temperature? this is human and geographical reasons. European Ethnography for white skin, white light makes the white skin looking pale. Even exaggeration, just like the color of the dead, so they prefer warm is natural. But we are yellow, Sun and natural white tone does not make us look pale. Also, much of Europe is located in the high latitudes, temperature lower zone, this is also the lead they prefer warm geographical reasons. However, we are located at the four seasons of the temperate zone, and no long cold winter, follow the Europeans choose too warm tone, it's not.
3, yellow light rain and fog penetrating power of suitable applications
There is a saying, that is, low color temperature of yellow light penetrating the ability of the rain and fog, so you should choose it. We do not deny that the yellow light on rain fog penetrating ability than white good this fact. However, we should understand that a lot of road lighting, is working in sunny accounted for most of the time, rain fog after all, the proportion of relatively small. Choose to adapt the mist weather warm color temperature luminaires, not distracting, the cart before the horse? in specific situations, such as Misty Harbor, is the low color temperature lighting of reasonable practices. Ordinary road lighting, or should select nearest Sun natural white colour temperature range, is both a science and energy-saving practices.
Above, we only from human identification and response mechanism to describe the lighting color temperature should choose close to nature of white light. Next, we go one step further from the angle of the color index to further on this point.
4, natural white light of the advantages of high color index
The Sun's natural white, after Mitsubishi mirror refraction, can be broken down into red, Orange, yellow, green, green, blue, purple, continuous spectrum, the wavelength of the seven rays 380nm-760nm. Sun natural white light contains full continuous visible spectrum.
The human eye can see objects, because the divergence from the objects or reflection of light into our eyes and senses. The basic mechanism for lighting is to bring light to the object, the object of absorption and reflection, and then from the outer surface of the reflex of objects into the eye, make people aware that the object's color and appearance. However, if this beam lighting light only a single color of light, then we can see that it is only with such a color object. It goes without saying that if the light is continuous with the full spectrum of light, then objects that appear in the face, and we in natural white light observed that the same vivid color tolerance and appearance.
Here you have to introduce a color index (Ra-colorrenderingindex/CRI) concept. The Sun's natural white light contains a complete and continuous spectrum, the body naturally white in the sun exposure, due to the interaction of various light, so that you can display the object's actual colors and appearance. So we put the Sun natural white color index defined as 100, which means that it can fully display the objects in the original true color. This is according to the human eye in Sun natural white light, the observed object's color, and standards.
Strictly speaking, in the nature of the standard white light exposure, every seemingly dull ordinary objects contour, can be broken down into standard colour plate shows a variety of color stops. In other words, if we use the standard white light to shine any color of an object, we can see its contour is the most "thick". However, if you use the monochromatic light, or the color is not very rich, deviations from the standard Sun natural light lights to light the object, its contours, as photosource "deficient" and not "thick" clear, even blurred.
Traditional dominant spectral HPS as 589.2nm and 589.6nm, are two very close to the line, close to the monochromatic light. High pressure sodium lamps of color index only 20-30. Therefore, high pressure sodium lamps of various objects will appear blurry. In order to enable people to see the original appearance of real objects, you need to enhance the intensity of the illumination, will be able to reach the eyes to see the real needs of the original object. Strengthening of illuminance, means that the increase in energy consumption. Even so, the observation of objects under the HPS clarity and true color, is never achieved a true natural white light. This is a lot of night-time shopper, to the day when I found the shopping night, not their favorite color, screaming, and initiator, it was the low color index of the light as well. Street side lights of the night market under pressure sodium low color weakness, is like window shopping night market must first note point oh.
5, low temperature and low-cost color index
The Sun's rays from morning to night on Earth, not every moment we feel the sunlight, are necessarily the natural white light. Because it also affected by the thickness of a cloud of absorption and refraction, reflection, interference, constitute a natural white light of various spectrum components and proportions, will change. Morning sunlight, are subject to heavy clouds, irradiation angle of refraction, so this time Golden sunshine, its color index has gone even 100, cannot be regarded as natural white light.
In accordance with the definition of color temperature, Kevlin 2800K-10000K belongs to Sun's color temperature range, this is the broad definition of color temperature of the Sun. However, only the color temperature 6500K light (also called D65) is a white standard color temperature, it is also the standard illuminants CIE D65. 6500K color temperature of light that are contained in the spectrum of the most complete, most close to the natural white light. The farther away from natural white color temperature of light source, its color index is lower.
Obviously, the lower the led color temperature, color index is more than the white LED. In the low color index of the light, take a close look at the original appearance of real objects, you need a higher light intensity to compensate for the color index. This means that people have to increase the lighting energy input, to get closer to the natural white light displays objects of the real original.
Practice shows that the use of close to nature white light, need only much less than other sources of illumination allows people faithfully sensing object of the real colours and original appearance. Low light means that less energy input, that means saving energy. We recommend using white light source close to nature as our lighting.
6, low color temperature LED light intensity decreasescosts
Since led packaging technology of doped a red pigment of LED, its light failure compared to white led faster, that is, its luminous intensity than white led down faster. Compensate for the light intensity decreases the cost of the loss is to increase the number of lamps LED packaging, that is, means that the increase in cost and energy, which is very reluctant to do so.
7. modify the inevitability of lighting standard times
Lighting of final purpose is to allow people to gain access to the dynamic and static objects realistic image of clarity. Now there is a color index of 70-90, close to the Sun naturally white LED lighting, is exactly what we improve lighting quality, reduce energy consumption of a very good chance.
High pressure sodium lamps of the color index of only 20-30. In order to it-led street lighting system, to obtain in the light of the objects observed identification and definition, it can only be used to increase the range of illumination value approach to efforts to achieve the purpose. Ministry of construction of the urban roadway lighting design standards ", is based on low-color index of sodium lamps-led lighting in the background, these standards were originally justifiable. However, the high color index of LED-lighting conditions, this standard becomes too high. Because, in high-color index of the led light source, to gain access to the object of the real image identification and observation of sharpness, need only much less than on HPS of illuminance required standard. In accordance with our many years of practical experience, just need less than the construction of the urban roadway lighting design standards for 30% of the illumination intensity, can reach and high pressure sodium, or even better identification and definition of lighting effects.
As with the HPS standards norms of illumination LED light source, means that unnecessary waste of energy. High intensity LED lighting, and even LED lighting will lead is too "loud" complaints; reducing the radiation intensity, not only can you gain energy savings, you can also obtain a "soft" lighting environment.
For high pressure sodium lamps and LED lamps both color index difference of 2-3 times of lighting, illumination standards changes certainly inevitable outcome. In our countries have yet to implement modifications of road lighting standards, only to draw the attention of the experts on this issue. Not offend the standards of existing national lighting, recommended or adopted the standard for low value is wise.
Therefore, LED lighting color temperature range and the choice of lighting standards, and lighting quality and energy conservation. Select nearest Sun natural white color temperature of LED lighting and appropriate lighting standards, it is only sensible and science, in line with the principles of energy saving.
8, lightingBrightness higher the better?
Currently, most domestic urban lighting brightness, are greater than the number of times specified by the State, as if to demonstrate the features of the city, in fact, this is very much a waste of energy of the error.
Please see the International Commission on illumination (CIE, 2003-2007), van-nipomo engineer (Ir.W.J.M.vanBommel) on average brightness and visibility of the results of the study:
This is an average brightness of pavement and display capabilities (RP) curve. Display capabilities of the RP refers to the human eye can see on the barrier of probability, that is commonly referred to as visibility.
The above study curves clearly to our transfer of this information:
Typically, when the average brightness of pavement 0.6cd/m2, the ability to display only 10% of the RP; when the average luminance reach 2cd/m2, the RP can reach 80%. While the average luminance of the local area to double on to 4cd/m2, visibility to reach 91.5%, i.e. more than double the consumption of energy, but visibility only improve 11.5%. Even if the average brightness on the ground to five times the average brightness, ground up 10cd/m2, the visibility can only increase to 95%. Spend four times less energy to improve the visibility of 15%. From an economic perspective, this is the candle. From optimization perspective, the average brightness 0.6-2cd/m2 is the optimization of economic choice.
Diffuse reflectance surface luminance and illuminance of L = E/π ρ is a ground reflection factor ρ and illumination product is related to the mathematical relationship. It just goes to show that the average illuminance or higher the better, and it is subject to the above basic embodied in the curve.
See the curve of the decision makers, we will naturally select 0.6-2cd/m2 of surface average brightness range, it does not and should not be blind pursuit of more light, the better the