A phone screen's proximity sensor works by using infrared light to detect when something is close to the screen, typically your face during a call.
Here's a breakdown:
- Infrared Light Emission: The sensor contains a tiny infrared LED (Light Emitting Diode) that emits a small pulse of infrared light.
- Reflection Detection: When an object, such as your face, is close to the phone screen, the infrared light bounces off of it.
- Sensor Measurement: The proximity sensor measures the amount of reflected light. According to our reference, it's the reflectance that is measured by the sensor, helping it determine the distance of the object.
- Signal Transmission: If the sensor detects a significant amount of reflected light, indicating close proximity, it sends a signal to the phone's operating system.
- Screen Deactivation: Upon receiving this signal, the operating system shuts off the phone screen. This prevents accidental touches while you are on a phone call and saves battery.
| Component | Function |
|---|---|
| Infrared LED | Emits a pulse of infrared light. |
| Proximity Sensor | Measures the amount of reflected infrared light. |
| Operating System | Receives the signal from the proximity sensor and turns the screen off |
Example:
When you place your phone to your ear during a call, the proximity sensor:
- Emits infrared light.
- Detects the reflected light from your ear or cheek.
- Sends a signal to the operating system.
- The screen turns off to prevent accidental presses and conserve battery.
In short, the proximity sensor uses a light reflection technique to determine if something is near the screen. It helps in managing the screen's power and prevent accidental touch during calls, as explained by the reference, which highlights that "the proximity sensor shines a light onto your skin, the sensor sees the light bouncing back, knows your face is there and sends a signal to the operating system telling it to shut down the screen."
