Infrared pyroelectric human body induction sensor, also known as pyroelectric sensor or human infrared sensor, is a sensor that can detect infrared rays emitted by humans or animals and output electrical signals.

Working principle

    The working principle of infrared pyroelectric sensor is based on the pyroelectric effect. When certain crystals (such as lithium tantalate, triglycine sulfate, etc.) are exposed to infrared radiation and the temperature rises, their surface charge will decrease, which is equivalent to releasing part of the charge. This phenomenon is called the pyroelectric effect. The sensor converts the released charge into voltage output through the amplifier, thereby realizing the detection of infrared radiation.

Structural composition

    Infrared pyroelectric sensor is mainly composed of filter, pyroelectric detection element and preamplifier.

    The filter is encapsulated at the top of the sensor housing, so that infrared radiation of a specific wavelength can selectively pass through and reach the pyroelectric detection element.

    The pyroelectric detection element is the core component of the sensor. It is made by plating metal electrodes on both sides of the pyroelectric crystal and then applying electrical polarization. It is equivalent to a flat capacitor with a pyroelectric crystal as the dielectric.

    The preamplifier is composed of a high-resistance field-effect transistor source follower, which is used to convert the weak current signal of the pyroelectric detector into a useful voltage signal output.

Sensor characteristics

    It does not emit any type of radiation: the infrared pyroelectric sensor does not emit any radiation when working, so it has the characteristics of good concealment.

    The device power consumption is very small: because the working principle of the sensor is based on the pyroelectric effect, its power consumption is very small.

    Low price: compared with other types of sensors, the price of infrared pyroelectric sensors is relatively low.

Application scenarios

    Infrared pyroelectric sensors are widely used in various scenarios of automatic perception of human presence, such as security monitoring, automatic lighting, automatic detection, smart home, etc.

    Security monitoring: installing infrared pyroelectric sensors at doorways, corridors, offices and other places can realize automatic perception of human presence and start security measures such as video recording and alarm of monitoring equipment.

    Lighting control: by setting up infrared pyroelectric sensors, it is possible to automatically switch on and off lighting equipment such as electric lights and night lights, thereby saving energy.

    Crowd flow detection in public places: Installing infrared pyroelectric sensors in public places such as gyms and cinemas can realize automatic detection of the number of spectators, so as to better manage the flow of people in the venue.

    Smart home: Installing infrared pyroelectric sensors at home can realize automatic perception of human entry and exit, and then realize the control of smart door locks, smart home appliances, etc.

    Infrared pyroelectric human body sensing sensors have broad application prospects and important practical value. However, in complex application environments, pyroelectric sensors may be susceptible to interference from various heat sources or sunlight sources, susceptible to interference from radio frequency radiation, and detection failure when the ambient temperature and human body temperature are close.

    Some scenes require enhanced white light filtering, some scenes require enhanced resistance to high-frequency interference, and some scenes require special solutions to animal interference false alarms, all of which put higher requirements on the technology of pyroelectric sensors.

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