Proximity sensor tester
Tests the sensor that blanks your screen during calls. On most phones it reports only two states, near and far, rather than a continuous distance.
| Sensor used | Infrared proximity sensor |
|---|---|
| Unit | Centimetres, but usually only two values |
| Useful range | Typically a few centimetres |
| Cannot do | Measure distance continuously, or work as a rangefinder |
The mechanism, not the marketing.
An infrared emitter sits near the earpiece with a detector beside it. When something close reflects that infrared light back, the sensor reports near.
Its job is to blank the screen when the phone is against your ear during a call, so it only needs to answer one question: is something close or not?
What a phone cannot do here.
- Most phones report a binary result. You will typically see one value with nothing nearby and a single fixed value when covered — no smooth scale in between, because the hardware does not provide one.
- It uses infrared, so very dark or non-reflective materials can absorb the beam and fail to register.
- A screen protector covering the sensor cutout is the usual cause of a screen that stays on during calls, or blanks when it should not.
Why does the proximity sensor only show two values?
Because that is all most hardware reports. It exists to detect a face during a call, which needs a near-or-far answer rather than a distance.
My screen stays on during calls — how do I check the sensor?
Run this test and cover the area near the earpiece. If the value never changes, the sensor is blocked — usually by a screen protector or case — or faulty.
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