Generally, the color selected for the LED beacon light has relatively low requirements for the driver's vision, and the colors used for the earliest traffic lights are also three colors of red, yellow and green.
The main reason is that the three colors can represent more traffic conditions. Red, green, yellow and blue are antagonistic colors that are not easy to be confused, and red and yellow have cultural meanings of caution. The red, yellow and green colors of the LED beacon lights are usually placed in order from left to right and top to bottom. The greater possibility is that it is consistent with the order in the culture and the direction of our language habits.
In fact, red and green beacon lights have strong penetrating power and are not simply divergent. They are easily recognized as hostile colors and are very suitable as LED signals.
Red, green, and yellow are the most suitable colors for LED beacon lights, which are related to people's visual structure and mental responses.
The human retina contains rod-shaped and three types of cone-shaped photoreceptor cells. The rod-shaped cells are particularly sensitive to yellow light, and the three types of cone-shaped cells are the most sensitive to red, green, and blue beacon light, respectively. Therefore, it is the easiest way for humans to distinguish between red and green.
Although the distinction between yellow and blue is simple, because the eyeball has fewer photoreceptor cells that are sensitive to blue light, red and green are better. In terms of emotional response, red is the most intense, followed by yellow, and green is a cool color, which has a quiet effect. Therefore, when people see the LED beacon light, they automatically use red for prohibition, yellow for warning, and green for safety.