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The pyroelectric infrared detection module is mainly composed of pyroelectric infrared detector, filter amplifier, voltage comparator and subsequent signal processing circuit.

The pyroelectric infrared detector is the core part of the pyroelectric infrared detection module, which is responsible for detecting the infrared signal from the human body and converting it into electrical signal output. The internal structure of a pyroelectric detector usually consists of two electrodes in series and a pyroelectric material. When the pyroelectric material absorbs infrared radiation, it causes a thermoelectric effect inside the material, resulting in an electrical signal.

Filter amplifier is an important part of pyroelectric infrared detection module, it mainly filters and amplifies the weak electrical signal output by pyroelectric detector, so that it can be better processed by the subsequent circuit. Generally, the filter amplifier consists of an operational amplifier and associated resistors, capacitors and other components.

Voltage comparator is a circuit used to compare input signal and reference signal in pyroelectric infrared detection module. It compares the electrical signal output of the filter amplifier with the reference voltage to determine whether the detected infrared signal is emitted by the human body. The output signal of the voltage comparator is usually a digital signal to facilitate subsequent signal processing.

The subsequent signal processing circuit mainly includes flip-flop, counter and output circuit, etc., which is used to process the signal output of the voltage comparator. The trigger is used to generate the trigger signal when the infrared signal from the human body is detected, the counter is used to count the number of times the human body moves, and the output circuit outputs the processed signal to the external device.

In general, the pyroelectric infrared detection module has the characteristics of wide detection range, high sensitivity and strong anti-interference ability in the application, so it is widely used in the fields of anti-theft alarm and motion detection.