led traffic lights red yellow green

Road traffic lights are a type of traffic lights used to allocate effective right of way to conflicting traffic flows to improve road traffic safety and road capacity. It is divided into two types: traffic control lights that give a directional signal and display a single color, such as traffic lights, and traffic control lights that indicate specific content such as pedestrians’ walk and stop (indicated by arrows), and the forward direction of vehicles. . In addition to meeting the general requirements of traffic lights, signal lights should also meet the following requirements: ①The light-emitting surface has a certain diameter, which is divided into 200mm and 300mm, and the surface brightness should be as uniform as possible. ②There are three light colors of red, yellow and green, and sometimes white is also used. ③Use hat brim and other measures to reduce the false display phenomenon when sunlight is obliquely shining on the light emitting surface of the lamp.
For traffic signal lights that emit a single color, the requirements: ①Light intensity: When the background brightness is 104cd/m2 and the viewing distance is 100m, the red light is 200cd, and the recommended ratio of red, yellow and green light intensity is 1:1.3:5. Except for urban highways and cities with bright backgrounds, the light intensity at night can be lower, so two light intensities of 200cd and 50cd can be used. ②Light intensity distribution: The light distribution is symmetrical. The light at the point where the light intensity drops to 50% of the peak intensity should be at 10° on the left and right of the optical axis and 5°-7° below the optical axis.

The pattern of the symbol signal light is to put people, bicycles, arrows, etc. on the surface of the circular lamp socket in a silhouette method, the silhouette part is illuminated, and the surrounding does not emit light. The design of the pattern must reduce the “astigmatism” phenomenon caused by large pupils or abnormal refraction errors (such as myopia)-a phenomenon similar to halo in the rain and fog, which reduces the recognizable degree of symbols. In addition, color can also express some specific meanings. To express heat or intensity, red is the strongest, followed by yellow. Green has the meaning of colder and calmer. Therefore, people often use red for danger, yellow for warning, and green for safety.