How do traffic light sensors work

Sensor is a kind of testing device, can feel the measured information, and will feel information, according to certain rules transform into electrical signal or other required information in the form of output, in order to meet the needs of information transmission, processing, storage, display, record and control requirements. The sensor you are quite common in our life. As we can see the traffic lights, at ordinary times is also a sensor, but how do the traffic light sensors work. In fact, by check information can learn sensor is the first step of automatic detection and automatic control. And the design of the traffic light is also on its principle. So, before know how do traffic light sensors work, let's understanding of the features of the sensor and the main features. 

   Sensor's features include: miniaturization, digital, intelligent, multi-functional, systematic and network, it not only promote the transformation and upgrading of traditional industries, but also possible to establish a new industry, becoming the new economic growth point in the 21st century. The existence and development of the sensor, let objects have sensory, such as touch, taste and smell let objects become live up slowly. And with the progress of science and technology, the sensor will be more and more attention and use. In life we common infrared sensor, uv scanning and so on, are inseparable from the relationship between with it. It also has a lot to do with the characteristics of the sensor. Sensor's static characteristic refers to the input signal to static, between the sensor's output and input has relationship to each other. When input and output had nothing to do with the time, so the relationship between them, namely the static characteristic of sensor available does not contain a time variable algebra equation, or by typing the abscissa, the corresponding output as ordinate and draw to describe the characteristic curve. Characterization of sensor static characteristics of the main parameters: linearity, sensitivity, hysteresis, repeatability, drift, etc. Through sensor features and characteristics, in the design of traffic lights, can easily understand how do traffic light sensors work as well as its working principle.