Firstly, the LED is a semiconductor diode, its life is very long. When flux attenuation to 80%, its life reached 25,000 hours. And metallic halide lamp life at 6000 ~ 12,000 hours, high-pressure sodium lamp life is 12000 hours.
Secondly, LED the basic structure is a electroluminescent semiconductor materials and placed in a lead on the shelf, then around sealed with epoxy resin, rise to protect the internal HPVV function, therefore LED the aseismatic performance is good. Thirdly, white LED light color than high-pressure sodium lamp. In the middle of the visual level, eye in high colour temperature environment than low colour temperature environment more easy to identify things. White LED the colour-display sex also much better than high-pressure sodium lamp, high-pressure sodium lamp of colour developing index only 20 right left, and white LED can achieve 65-80. Fourthly, LED can realize more perfect dimmer function. Because the work scope is larger, LED the light output and working current is proportional to, so can reduce the current methods to dimmer. In addition, because doing frequent switch on the LED without too much damage, LED the dimmer still can use the pulse width adjustment methods to get through adjusting voltage 390v and working frequency and can effectively adjust LED the luminous intensity. Lastly, the lamps and lanterns of optical system inside, LED light source flux loss minimum. With traditional light source is different, LED half space shine light sources. High-pressure sodium lamp or metal halide lamp is whole space shine illuminant, need to one and a half space out shoot the light to change direction to half space 180 ° inside. When we rely on a reflector to complete, reflector light absorption and illuminant itself against light is inevitable. Instead of using LED light source, can't existence as the losses, the utilization rate of light than traditional illuminant high. Finally, LED light does not contain harmful mercury, unlike high-pressure sodium lamp or metal halide lamp in scrap when environmental harm.
The night comes, you ride in the street, street lamp faithfully accompanying you and make you safely home. Street lamp to bring your visual comfortable feeling first comes from pavement brightness is evener, then along the people or things can also see that you may know the situation may be unexpected. Street lamp lighting reached such requirements, its light distribution must be reasonable. Therefore, if you use LED lamp, although it supports with good light color, long life, light function etc advantages, its light distribution level is still auralability. At present, LED lamp just start, need to consummate unceasingly, whether lamps optical structure design, or cooling techniques, are still in improved unceasingly.
LED lamp and use traditional light lamps optical design way is different. Traditional light source is through the use of reflector lamps a light source of the flux will equally to suffer as the pavement. And LED lamp illuminant by very multiple LED, through design and each LED by the projection direction, make according to the pavement obtain homogeneous intensity of illumination.
At present, LED lamp at times and branch amongst the prospect for application of very good. Times are amongst the city road network combined with thingseses composed, distributing traffic role within the road. Times the intensity of illumination requirement achieves amongst the 15lx, intensity of illumination evenness 0.4, average brightness demand 1.0 CD/m2, the brightness of total evenness 0.4, the brightness of longitudinal evenness 0.5, threshold value increment more than 10. Meet energy level LED lights, and in lighting quality to achieve above requirement while lighting power density should be less than national standard regulation, when lane number p four, lighting power density acuities 0.70, lane number < four, lighting power density acuities 0.85. In order to satisfy the above-mentioned requirements, LED lamp of light distribution shape should be subject to strict requirements. In the street, the longitudinal beam should be projected onto a distant place, making the lamps and lanterns of spacing increase. The streetlights below, light intensity should is the smallest, with the elevation gamma increases, light intensity I 'increased. When I ', and gamma satisfy certain function relations, pavement can get uniform illumination. This function relation is as follows:
Of course, since the optical design complexity, light distribution shape can fully comply with this function relation, and can reduce the gamma Angle projection range, reduce lamp spacing to obtain even the intensity of illumination. In the street the longitudinal, maximum light intensity with the road ZongXian projection direction should be into certain Angle c, the size of the Angle of c depends on the road width, see figure 2. In perpendicular to the direction of the road, on the street lamp light distribution curve shape can also press this function relation design, gamma Angle range depends on the road width (c = 90 DHS) and sidewalks position (c = 270 DHS, see figure 3).
At present, in many factories design LED lamp also is filled with light distribution rasodilation example. Such as figure 4 is a section of 120WLED street lamp light distribution curve. Its the biggest light intensity 15 ° c Angle, by gamma-irradiation ° Angle 5.75. C = 0 °, 180, 15 ° of light distribution curve shape close in formula 1 the function equation. The lamps and lanterns in a four-lane times dry road, bilateral symmetry decorate, when light pole height is 8 meters, lamps and lanterns spacing 30 meters, lighting quality conforms to the national about road lighting standard requirements, the results presented in table 1. Its lighting power density (LPD) is 0.70, also achieved in high pressure sodium lamp lighting power density requirements. |
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