In recent years, ultrasonic sensors, similar to infrared sensors, have been applied in automatic detection of moving objects. Ultrasonic sensors are mainly using the doppler principle, launch out through crystals of high frequency ultrasound can perceive more than the human body, the selection of a typical 25 ~ 40 KHZ wave, and then control module to detect the frequency of the reflected wave, if the area is the object movement, reflected wave frequency will have slight fluctuations, namely, the doppler effect, to determine the lighting area of the moving object, so as to achieve the goal of control switch.
The longitudinal oscillation of ultrasonic wave can be propagated in gas, liquid and solid, and its propagation speed is different. It also has refraction and reflection phenomenon, in the air the propagation frequency is low, the attenuation is fast, but in the solid, the liquid attenuation is small, the propagation is far. Ultrasonic sensors take advantage of these characteristics. The ultrasonic sensor has the characteristics of large sensitive range, no blind area and no interference from obstacles. It has been proved to be the most effective method to detect the motion of small objects. Therefore, the system composed of LED lamps can be sensitive to the control switch. Due to the high sensitivity of the ultrasonic sensor, the air vibration, the ventilation heating and cooling system and the movement of the surrounding adjacent space will cause the ultrasonic sensor to trigger by mistake, so the ultrasonic sensor needs to be calibrated in time.

The temperature sensor NTC(negative temperature coefficient) is widely used as the over-temperature protection of LED lamps. LED lamps such as the use of high-power LED light source, it is necessary to use a multi-wing aluminum radiator, because the room lighting LED lamps itself is very small, heat dissipation problem to the present is one of the biggest technical bottleneck.
If the LED lamp heat dissipation is not satisfactory, it will lead to the LED light source due to overheating and early light decay. After the LED lamp is opened, the heat will also automatically rise due to the hot air and enrich to the lamp, affecting the life of the power supply. Therefore, when designing LED lamps, NTC can be attached to the aluminum radiator near the LED light source, so as to acquire the lamp's temperature in real time. When the temperature of lamp cup aluminum radiator increases, this circuit can be used to automatically reduce the output current of constant current source to cool the lamp. When the temperature of the lamp cup aluminum radiator rises to the limit value, the LED power is automatically turned off to realize the over-temperature protection of the lamp. When the temperature drops, the lamp is automatically turned on again.