Overview: Sources of signal lights:

Commonly known as traffic lights. (Common traffic lights in China) In the early 19th century, in York City in central England, red and green clothes represented different identities of women. Among them, a woman in red dress said that I was married, while a woman in green dress was unmarried. Later, in the front of the London Parliament Building, there was a frequent accident of the carriage rolling, so people were inspired by the red and green. On December 10, 1868, the first member of the signal light family was born in the square of the London Parliament Building. The lamppost designed and manufactured by British mechanic De Hart is 7 meters high. There is a red and green lantern on the body - the gas traffic signal light, which is the first signal light on the city street. At the foot of the lamp, a policeman with a long pole can pull the belt to change the color of the lantern as he pleases. Later, a gas lampshade was installed in the center of the signal light, and two red and green glass were alternately blocked in front of it. Unfortunately, only 23 days of gas lamps suddenly exploded, causing a police officer on duty to ruin his life.