Here's how they typically work:

IR Emission and Reception: The module consists of two main components: an IR emitter (usually an IR LED) and an IR receiver (usually a photodiode or phototransistor). The IR emitter emits an infrared light beam, and the IR receiver detects the reflected or scattered IR light.

Reflection from Objects: When the emitted IR light encounters an obstacle or object in its path, some of the light is reflected back toward the IR receiver.

Signal Processing: The module includes signal processing circuitry to analyze the received IR signal. It measures the intensity of the reflected IR light and determines whether an object is present or not based on the strength of the reflected signal.

Output Signal: The module typically provides a digital output signal (often labeled as "Obstacle Detected" or similar) that indicates the presence or absence of an obstacle. When an object is detected, the output goes high (1); when no object is detected, the output goes low (0).

Distance Sensing: Some modules can also provide analog output signals or distance information based on the strength of the reflected IR light. These analog outputs can be used to estimate the distance to the obstacle.