High-collimation and high-performance LED warning light

Highly professional warning lights are commonly used in high-rise buildings, navigation, aviation and other places with high safety requirements. Take Taiwan as an example. As the height of buildings increases, many buildings and chimneys must be equipped with obstruction lights to maintain flight safety. In addition, places such as the sea and airports must have warning lights as a source of light for channel guidance, so there is an increasing demand in the market; however, due to the general technical bottlenecks in the current market on the island, the main focus is on the production of general warning lights. There are almost no companies that can produce advanced warning lights for aviation and navigation, so the warning lights used in Taiwan often have to be purchased overseas. For example, Taipei 101 and Taiwan High Speed ​​Rail both spend a lot of money to purchase warning lights from abroad. Therefore, it is hoped that through technological breakthroughs, extremely high-value products can be created.

1. Principle, architecture and method

The main software used is ASAP, an optical simulation software, for ray tracing and statistical and simulation data.

1.1 LED light source lampshade

First, we used a collimated LED lamp designed by a senior in the laboratory as shown in Figure 1. The result can be seen in Figure 2. The divergence angle is between -3 and 3 degrees, and its uniformity can reach 83.6% as shown in Figure 3.

1.2 Warning light internal structure

1. Reflective mirror:

Using the law of reflection: the angle of incidence is equal to the angle of reflection, and when the incident ray remains unchanged, the plane mirror rotates and the reflected ray changes to an image formed by an angular plane mirror.

We use this reflective mirror to reflect light in all directions because the target vertical emission angle is 0~6°, and the divergence angle of the collimated LED light is -3~3 degrees, so the reflected light needs to be rotated 3 degrees, and the mirror only needs to be rotated 1.5 degrees, so the angle between the reflective mirror and the horizontal is 45+1.5=46.5 degrees. The design is shown in Figure 4.

After a single collimated LED light is directed upwards and passes through the reflective surface, the upward collimated light is reflected to the horizontal direction. The vertical divergence angle of the light can be measured to be between 0 and 6 degrees, the horizontal divergence half-intensity angle is between -8 and 8 degrees, and the horizontal illumination uniformity is only 36%, as shown in Figure 6; Figure 5 is a schematic diagram of the surface to be tested. Because the illumination distribution will be circularly symmetrical, the illumination distribution diagram in Figure 7 only captures the range of 0 to 30 degrees.

2. Cylindrical mirror:

Because the uniformity in the horizontal direction is not very ideal, only 36%, we use the characteristics of light refraction to design a cylindrical mirror to make the light distribution in the horizontal direction more uniform. The optical path diagram is shown in Figure 8.

In this way, the cylindrical mirror is used to make the horizontal direction a divergent light, as shown in Figures 9 and 10.

After the light passing through the reflective mirror passes through the refraction cover, it can be measured that the vertical divergence angle of the light is still between 0 and 6 degrees, but the horizontal divergence half-intensity angle has been dispersed to about -25 to 25 degrees, and the illumination uniformity in the horizontal direction has increased to 63%, as shown in Figures 12 and 13; Figure 11 is a schematic diagram of the surface to be tested

3. Results

The lampshade, reflective mirror and cylindrical mirror of the LED light source are combined, and the overall structure diagram is shown in Figure 14. The light distribution of the entire system is controlled. Using the ASAP optical simulation software, the surface to be detected is placed eight kilometers away, as shown in Figures 15 and 16.

The measured intensity distribution is shown in Figure 17. The red line represents the light intensity distribution in the vertical direction. The target vertical emission angle is 0-6°. The illuminance distribution is shown in Figure 18. The illuminance uniformity is 50%.

4. Conclusion

In this study, the design of LED warning lights was simulated using optical software to place the entire system of collimated and uniform LED lampshades, reflectors and refraction lights. It was found that the vertical emission angle of the light on the detection surface 8 kilometers away was about 0-6°, and the overall (6 LEDs) output effective light uniformity was about 50%; since the application environment of this type of product is a place with high safety requirements, the use specifications of the lamp light intensity (cd/m2), viewing distance and angle will be determined according to different places, and the above results have met the relevant specifications.