Types of Sensors Used in LED Lighting

The technology of the sensor, which is a device for signal acquisition and electromechanical conversion, is highly advanced. In recent years, sensor technology has made great strides towards miniaturization, intelligence, multifunctionality and low cost. Various types of sensors can be combined with LED technology, including in industrial lighting, to form an intelligent control system. The sensor converts the collected physical signals into electrical signals. The collected signals are then intelligently processed by the integrated circuit based AD (analog to digital) converter, MCU (microcontroller) and DA (digital to analog) converters to control the on-off of the LED lighting. In addition, various control requirements can be set in the microcontroller (MCU) to control the switching time, brightness, color rendition and color change of LED lights so that the intelligent lighting control achieves its goal. Continue reading our article to learn more about sensor types and functions;

-Photosensitive Sensor

This type of sensor is an electronic sensor that can control the automatic opening and closing of the circuit due to the change of brightness in the morning and evening (sunrise and sunset). Photosensitive sensors can automatically control the on and off of LED lights according to the weather, time period and region. These sensor types are LED street lights, area lights, garden lights, courtyard lights, etc. It can be used with outdoor lighting such as During daylight hours, it reduces output power or is instructed by sensors to turn off all lights. On the contrary, at night, the sensors are instructed for lighting and make the lights turn on automatically after a certain time.

-Infrared Sensor

Infrared sensors detect and work with infrared rays emitted by the human body. The infrared sensor converts the infrared radiation energy of the Fresnel filter lens into an electrical signal. As long as there is no human movement in the detection area of ​​the passive infrared detector, the infrared sensor only detects the background temperature. When the human body is detected, the pyroelectric infrared sensor detects the difference between body temperature and background temperature through the Fresnel lens. After these signals are collected, they are compared with existing detection data in the system to determine if there is indeed someone or another infrared radiation object entering the detection area.

-Ultrasonic Sensor

Ultrasonic sensors are similar to infrared sensors. Especially in recent years, there are many applications for automatic detection of moving objects. This type of sensor uses the Doppler Principle to emit more high-frequency ultrasonic waves than the human body can detect through a crystal oscillator. Generally, a 25 to 40 kHz wave is selected and the control module detects the frequency of the reflected back wave. If there is object movement in the area, the frequency of the reflected wave will have a slight fluctuation. This is called the Doppler effect. Installed lamps or lights evaluate the movement of objects in the lighting area to achieve the on-off control purpose.

Ultrasonic sensors have a wide sensitivity range, have no visual blind areas and are unaffected by obstacles. It is the most effective method for detecting small object movements. Therefore, LED luminaires with an ultrasonic system may consist of sensitive control switches. Due to the high sensitivity of ultrasonic sensors, it is necessary to calibrate the ultrasonic sensor in a timely manner, as vibrations from air vibration, ventilation heating-cooling system and surrounding space may cause false triggering of the ultrasonic sensor.

-Temperature Sensor
Temperature sensors NTC (negative temperature coefficient) are widely used in overtemperature protection of LED lamps. If LED lamps use a very high power light source, they must use a multi-blade aluminum heat sink. If the heat dissipation performance of LED lamps is not good, it will cause lighting degradation of the LED light source due to overheating and adversely affect the life of the LED. High-bay lamps operating in high-temperature environments such as a steel mill can work with temperature sensors to capture the real-time temperature of the lamp. When the temperature inside the luminaire chamber gets too high, this circuit works and automatically reduces the output current and cools the light. When the temperature rises to the limit setting value, the LED power is automatically turned off to realize the over-temperature protection. The lamp turns on again when the temperature drops to a certain level. Due to the small internal space, the heat dissipation problem has been one of the biggest technical problems until now.

-Sound Sensor
sound sensor; It consists of an audio control sensor, an audio amplifier, a channel selection circuit, a delay circuit and a thyristor control circuit. Usually the audio comparison result is used to decide whether to start the control circuit. The original value setting of the sound sensor is given by the regulator. While working, the sound sensor constantly compares the external sound intensity with the original value. When the original value is exceeded, the audio signal is transmitted to the control center.

-Microwave Sensor
A microwave inductive sensor is a moving object detector designed using the Doppler Effect principle. It detects whether the position of the object moves without contact and generates a corresponding switching operation. When someone enters the detection area and meets the lighting requirements, the sensor switch will automatically open, the load device will start and the delay system will be activated. The load device continues to operate as long as the human body does not leave the sensing area. When the human body leaves the sensing area, the sensor starts to calculate the delay, the delay ends, the sensor switch closes automatically and the load device stops working. It is safe, convenient, smart and efficient.