Six commonly used sensors for LED intelligent lighting

Photosensitive sensor
A photosensitive sensor is an ideal electronic sensor that can control the circuit to automatically switch on and off due to changes in illumination during dawn and dusk (sunrise, sunset). The photosensitive sensor can automatically control the opening and closing of LED lighting fixtures based on weather, time period, and region. By reducing its output power during bright daylight hours to lower power consumption, a convenience store with an area of 200 square meters can reduce power consumption by up to 53% compared to using fluorescent lamps, and has a lifespan of approximately 50000 to 100000 hours. In general, the lifespan of LED lighting fixtures is around 40000 hours; The colors of the emitted light can also be varied in RGB (red, green, blue) colors to make the lighting more colorful and the atmosphere more lively.
A photosensitive sensor is an ideal electronic sensor that can control the circuit to automatically switch on and off due to changes in illumination during dawn and dusk (sunrise, sunset). The photosensitive sensor can automatically control the opening and closing of LED lighting fixtures based on weather, time period, and region. By reducing its output power during bright daylight hours to lower power consumption, a convenience store with an area of 200 square meters can reduce power consumption by up to 53% compared to using fluorescent lamps, and has a lifespan of approximately 50000 to 100000 hours. In general, the lifespan of LED lighting fixtures is around 40000 hours; The colors of the emitted light can also be varied in RGB (red, green, blue) colors to make the lighting more colorful and the atmosphere more lively.

Infrared sensor
Infrared sensors work by detecting the infrared radiation emitted by the human body. The main principle is that the infrared radiation emitted by the human body, which is about 10 μ m in size, is enhanced by a Fresnel filter lens and collected on a passive infrared (PIR) detector. When a person is active, the emission position of the infrared radiation will change, causing the element to lose charge balance and release charges outward through the pyroelectric effect. The infrared sensor converts the change in infrared radiation energy transmitted through the Fresnel filter lens into an electrical signal, that is, thermoelectric conversion. When there is no human movement in the detection area of the passive infrared detector, the infrared sensor only senses the background temperature. When a human enters the detection area, the difference between the human body temperature and the background temperature is sensed by the pyroelectric infrared sensor through a Fresnel lens. After the signal is collected, it is compared with the existing detection data in the system to determine whether there is really a human or other infrared source entering the detection area.
Passive infrared sensors have three key components: Fresnel filter lens, pyroelectric infrared sensor, and matched low-noise amplifier. The Fresnel lens has two functions: one is the focusing effect, which refracts the pyroelectric infrared signal onto the PIR; the other is to divide the detection area into several bright and dark areas, so that moving objects/people entering the detection area can generate a changing pyroelectric infrared signal on the PIR in the form of temperature changes. Generally, a low-noise amplifier is also matched. When the ambient temperature on the detector rises, especially when it approaches normal human body temperature (37 ℃), the sensitivity of the sensor decreases. It compensates for the gain and increases its sensitivity. The output signal can be used to drive electronic switches and achieve switch control of LED lighting circuits.

Ultrasonic sensor
Ultrasonic sensors, similar to infrared sensors, have been increasingly used in automatic detection of moving objects in recent years. Ultrasonic sensors mainly use the Doppler principle to emit high-frequency ultrasonic waves beyond what the human body can perceive through a crystal oscillator. Typically, 25-40kHz waves are selected, and the control module detects the frequency of the reflected wave. If there is object movement in the area, there will be slight fluctuations in the frequency of the reflected wave, known as the Doppler effect, to determine the movement of objects in the illuminated area and achieve the purpose of controlling the switch.
The longitudinal oscillation characteristics of ultrasound can propagate in gases, liquids, and solids at different speeds; It also exhibits refraction and reflection phenomena, with lower propagation frequency and faster attenuation in air, while it attenuates less and propagates further in solids and liquids. Ultrasonic sensors utilize these characteristics of ultrasound. Ultrasonic sensors have the characteristics of a large sensitive range, no visual blind spots, and are not affected by obstacles. They have been proven to be the most effective method for detecting small object movements. Therefore, the system composed of LED lamps can sensitively control the switch. Due to the high sensitivity of ultrasonic sensors, air vibrations, ventilation, heating, and cooling systems, as well as movements in adjacent spaces, can cause false triggering of ultrasonic sensors. Therefore, ultrasonic sensors need to be calibrated in a timely manner.

Temperature sensor
The NTC (Negative Temperature Coefficient) temperature sensor has been widely used for over temperature protection of LED lighting fixtures for a long time. If high-power LED light sources are used in LED lamps, multi wing aluminum heat sinks must be used. Due to the small space of indoor lighting LED lamps, heat dissipation is still one of the biggest technical bottlenecks.
If the heat dissipation of LED lamps is not satisfactory, it will cause early light decay of the LED light source due to overheating. After the LED lamp is turned on, the heat will also accumulate towards the lamp head due to the automatic rise of hot air, affecting the lifespan of the power supply. Therefore, when designing LED lighting fixtures, an NTC can be closely attached to the aluminum heat sink near the LED light source to collect the temperature of the fixture in real time. When the temperature of the aluminum heat sink of the lamp cup rises, this circuit can be used to automatically reduce the output current of the constant current source to cool down the fixture; When the temperature of the aluminum heat sink of the lamp cup rises to the limit setting value, the LED power supply will be automatically turned off to achieve over temperature protection of the lamp. When the temperature drops, the lamp will automatically turn on again.

Voice controlled sensor
A voice controlled sensor (microphone array) consisting of a sound control sensor, an audio amplifier, a channel selection circuit, a delay turn-on circuit, and a thyristor control circuit. To determine whether to activate the control circuit based on the sound comparison results, a regulator is used to set the original value of the sound control sensor. The sound control sensor continuously compares the external sound intensity with the original value, and when it exceeds the original value, it sends a “sound” signal to the control center. Sound control sensors are widely used in corridors and public lighting places.

Microwave induction sensor
Microwave induction sensor is a mobile object detector designed using the principle of Doppler effect. It detects whether the position of an object has moved in a non-contact manner, and then generates corresponding switch operations. When someone enters the sensing area and meets the lighting requirements, the sensing switch automatically turns on, the load appliance starts working, and the delay system is activated. As long as the human body does not leave the sensing area, the load appliance will continue to work. After the human body leaves the sensing area, the sensor begins to calculate the delay. When the delay ends, the sensor switch automatically closes and the load electrical device stops working. Truly achieving safety, convenience, intelligence, and energy efficiency.


Post time: Nov-29-2024