1. The most important feature of LEDs for illumination is the function of directional emission of light, because power LEDs are almost always equipped with reflectors, and the efficiency of such reflectors is significantly higher than the reflector efficiency of the lamps. In addition, the efficiency of the self-reflector has been included in the LED efficacy detection. Road luminaires using LEDs should utilize the characteristics of directional emitted light of LEDs as much as possible, so that each LED in the road luminaire directly directs the light to each area of the road surface to be illuminated, and then uses the auxiliary light distribution of the luminaire reflector to realize Very reasonable light distribution for road lamps. It should be said that the road lamps should meet the requirements of illumination and illumination uniformity of CJJ45-2006 and CIE31 and CIE115 standards. The function of three light distributions in the lamps should be better. The LED with reflector and having a reasonable beam output angle has a good primary light distribution function. In the luminaire, a good secondary light distribution function can be realized by designing the mounting position of each LED and the direction of the emitted light according to the height of the road lamp and the width of the road surface. Reflectors in such luminaires are only used as an auxiliary three-time light distribution to ensure better uniformity of road illumination.
In the design of the actual road lighting fixtures, each LED can be fixed on the luminaire with the spherical universal joint under the premise of basically setting the direction of each LED, when the luminaire is used at different heights and illumination widths. At the same time, the spherical gimbal can be adjusted to achieve satisfactory results for each LED. When determining the power and beam output angle of each LED, the LEDs can be calculated according to E(lx)=I(cd)/D(m)2 (the inverse law of the intensity and illuminance distance). The power that the beam should have when outputting the angle, and the light output of each LED can be predicted by adjusting the power of each LED and the different power output from the LED driver circuit to each LED. These adjustment methods are unique to road lamps that use LED light sources. By fully utilizing these features, it is possible to reduce the illumination power density under the premise of satisfying the illumination of the road surface and the illumination uniformity, thereby achieving the purpose of energy saving.