The important technical threshold of LED street light in product development is optical design, because of the good light distribution characteristics of lamps, the light of LED street light can be effectively and evenly distributed on the illuminated road surface. Optical design (greater light utilization, light distribution) can be completed with the help of related software, such as TRACEPRO, LEDs with different brands, light types and different folded lenses have different requirements for LED spacing and aluminum substrate thickness. The optical design effect of the luminaire can be achieved with the help of software to achieve a more reasonable light distribution curve

In the design of the lamp, the light emitted by the LED closest to the lamp body wall should not be blocked, and the inner wall of the lamp should be designed to have a certain angle, or chrome plating can be used to obtain better light output. It is to add reflectors. The angle of the reflectors can be calculated by the software. The reflectors can increase the utilization rate of stray light by about 15%.

Traditional lamps and lanterns have long used incandescent and fluorescent light sources as reference objects to determine the optical and shape standards of lamps. Therefore, the design of LED lamps should consider abandoning traditional lamps and LED light-emitting modules. The optical characteristics are fully considered to be LED light sources. Specially designed different lamps, the optical system design content of LED lamps mainly includes the following aspects:

1) Determine the shape of the optical system, the number of LEDs and the size of the power according to the needs of the lighting object and luminous flux.
2) Design a combination of several LEDs into a secondary light source of a point light source, a ring light source or a surface light source, and calculate the optical system of the secondary light source according to the combined secondary light source.
3) In the design of the secondary light source that constitutes the lighting optical system, the control of the light distribution of each LED is very important.

Using cylindrical light guide plate in secondary optical technology
Using cylindrical light guide plate in secondary optical technology

At present, the LED street lights on the market, the light source part is mainly divided into two ways;
1) A single 1W high-power white LED array.
2) High-power integrated packaged LED modules.
Although the national standard for LED street lamps has not yet been issued, the light distribution of LED street lamps should achieve the following goals when referring to the requirements of traditional light source road lighting standards: suitable average road brightness, high total and longitudinal illuminance uniformity, suitable Ambient ratio, glare control, etc.

From the light distribution curve, to achieve the above goals is mainly to obtain the light intensity distribution of the bat airfoil through appropriate optical design, so as to obtain the rectangular light spot distribution on the road surface. However, the package lens (ie, the primary optical lens) of ordinary high-power white LEDs is not suitable for direct application to LED street lamps, so a secondary optical lens should be added to the primary optical lens of each high-power white LED. The secondary optical lens can achieve better results. The wave-shaped optical lens mask is directly designed outside the once-packaged LED light source, and the lens mask is used to achieve the function of the secondary optical lens of the entire LED street light light source.

As the packaging industry moves closer to the needs of the downstream application industry, a primary optical lens with a special shape is developed and designed, which is directly installed when the LED chip is packaged. It has the characteristics of small size and low cost, and fully meets the requirements of LED street lamps and road lighting. With the advancement of packaging technology, the packaging method of white LEDs has gradually shifted from a single 1w high-power 1.ED device to a high-power integrated packaged LED module. The power of the current high-power integrated packaged LED modules can reach up to 100W or more, but the large light-emitting area of ‚Äč‚Äčthis type of light source brings difficulties to the optical light distribution design.

Using the intelligent control technology of high-power white LED with enhanced red light, a light source module with a color rendering index of more than 90 and an adjustable correlated color temperature in the range of 2500~8000K can be obtained. This technology utilizes the integrated photoelectric conversion chip on the package substrate to monitor the white light colorimetric parameters of the LED module in real time. The photoelectric conversion chip feeds back the detected changes in the colorimetric parameters of the white light to the intelligent control system. It can output white light with optimal colorimetric performance, and can ensure that the output of the LED module maintains the set correlated color temperature range and color rendering index. Indirect monitoring of the junction temperature of the power LED chip, when the junction temperature exceeds the preset temperature of the system, the system can automatically adjust the heat dissipation path of the cooling system or reduce the power of the LED. The LED module can be composed of a single 1W high-power white LED array or a high-power integrated packaged LED module, which has been used in the design of LED street lamps.

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