1. The biggest feature of LED for lighting is its directional light emission function, because almost all power LEDs are equipped with reflectors, and the efficiency of such reflectors is significantly higher than that of lamps. In addition, the light efficiency of LED has included the efficiency of its own reflector. The road lamps using LED shall make full use of the directional emission characteristics of LED as far as possible, so that each LED in the road lamps can directly direct the light to each area of the road to be illuminated, and then use the auxiliary light distribution of the lamp reflector to achieve a reasonable comprehensive light distribution of the road lamps. It should be said that road lamps should truly meet the requirements of CJJ45-2006, CIE31 and CIE115 standards for illuminance and uniformity of illuminance, and the function of three times light distribution should be included in the lamps to better achieve., LED with reflector and reasonable beam output angle has good primary light distribution function. In the lamp, the installation position and emission direction of each LED can be designed according to the height of the road lamp and the width of the road surface to achieve a good secondary light distribution function. The reflector in such lamps is only used as an auxiliary tertiary light distribution method to ensure better uniformity of road illumination.

In the design of actual road lighting lamps, each LED can be fixed on the lamp with a spherical universal joint on the premise that the setting direction of each LED is basically set. When the lamp is used at different heights and irradiation widths, the spherical universal joint can be adjusted to make the irradiation direction of each LED achieve satisfactory results. When determining the power and beam output angle of each LED, the power that each LED should have when basically selecting the beam output angle can be calculated according to E (lx)=I (cd)/D (m) 2 (inverse square law of light intensity and illuminance distance), and the light output of each LED can reach the expected value by adjusting the power of each LED and the different power output to each LED by the LED drive circuit. These adjustment methods are unique to the road lamps using LED light sources. Taking full advantage of these characteristics can reduce the lighting power density on the premise of meeting the illumination and uniformity of the road surface, so as to achieve the purpose of energy conservation.

2. The power supply system of LED street lamps is also different from the traditional light source. The constant current drive power required by LED is a cornerstone to ensure its normal operation. The simple switching power supply scheme often brings damage to LED devices. How to make a group of LED tightly compressed together safe is also an indicator of LED street lamps. The requirement of LED on the drive circuit is to ensure the constant current output characteristics. Because the junction voltage relative change area is very small when the LED is working in the forward direction, ensuring the constant LED drive current basically guarantees the constant LED output power. For the current situation of unstable power supply in China, it is necessary that the driving circuit of road lamp LED has constant current output characteristics, which can ensure the constant light output and prevent the LED from operating at excessive power.