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1 Introduction
With the rapid development of the economy and society, electric energy is getting more and more tense, and the phenomenon of wasted energy still exists. In many colleges and universities, there is a problem that classroom lighting management is not in place. At night, the empty classrooms are still brightly lit. For such large buildings, lighting energy saving is becoming more and more important. The widely used lighting energy-saving switches are basically voice-activated, contact-type, etc. Due to the limitations of use, these switches can only be used as an auxiliary part of the control system. To realize the intelligent and energy-saving indoor lighting system, the most important point is that the system can detect and judge the presence of human beings. The passive pyroelectric infrared sensor on the market is limited to detecting dynamic human body and people who are sitting in the classroom. Do not react. The project team designed a low-cost, low-power indoor intelligent control system based on the active pyroelectric infrared sensor.
2. Overall system function and structure
2.1 Features
Pyroelectric infrared technology is used to detect whether there is any person in the room. When someone enters the room, the sensor detects the infrared rays emitted by the human body and generates a current signal. The signal is processed by the integrated processing circuit IC and transmitted to the single-chip microcomputer. The single-chip microcomputer controls the illumination through the control relay. The switch of the device, after which the single-chip computer controls the motor to rotate the sensor at intervals. If there is always a human body in the room, the lighting device remains energized. After the person leaves, the sensor closes the load due to the detection of the human body in the next detection cycle. It can achieve the effect of "people to light, people in the light, people off the light, safe and energy saving".
The intensity of the indoor light is detected by a photoresistor. Using the illumination characteristics of the photoresistor, the current generated by the photoresistor changes with a change in relative light intensity at a certain voltage, and these electrical signals are sent to the single-chip microcomputer, and the switch of the lighting appliance is automatically controlled by the single-chip microcomputer.
In terms of model power consumption, the sensor is up to 5W in the case of rotation and up to 0.5W in the static case. If the sensor is properly arranged in the classroom, energy-saving control of the lighting device can be realized.
2.2 structure block diagram
The design consists of an active pyroelectric infrared sensor detection module, a single-chip control module, an ambient light intensity detection module, and a relay execution module. The structure is shown in Figure 1.
Figure 1 block diagram
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