Background
Touchscreen dead zones and ghost touches
Most phones, tablets, and touch laptops use a projected capacitive touchscreen: a fine grid of transparent electrodes that senses the small change in capacitance when a finger comes close. A controller scans the grid many times per second and reports each touch point. Dead zones, missed swipes, and phantom touches come from that grid, the layers on top of it, or the electrical environment around it.
Common causes of dead zones
- A cracked or damaged digitizer. Even a hairline crack can break electrode lines, which often leaves a straight strip that does not respond.
- Screen protectors. Thick protectors, air bubbles, or a protector that lifts at the edges can reduce sensitivity in that area. Remove or replace it and test again.
- Moisture or dirt. Water droplets and greasy films change the capacitance and confuse the controller.
- Edge rejection. Phones with curved or very thin edges deliberately ignore touches near the edge to prevent accidental input from your palm. That is a setting, not a defect.
- Software. A frozen app or an outdated system can stop reporting touches. A restart rules this out.
Ghost touches
Ghost touches are taps or swipes nobody made. A frequent cause is electrical noise from a cheap or faulty charger: the noise disturbs the touch sensor while the device is plugged in. Test with the charger unplugged. Other causes are a damaged display assembly, a swollen battery pressing on the screen, or moisture under the glass. If ghost touches come with a lifting or bulging screen, stop charging the device and get it checked, because a swollen battery can be a safety risk.
How many fingers does it support?
Most modern phones and tablets track up to 10 simultaneous touch points, and touchscreens certified for Windows support at least 5. The browser reports the device’s declared maximum as navigator.maxTouchPoints, and this test also counts how many touches it actually saw at once. If you see fewer than expected, try placing fingers further apart: touches very close together can merge into one.
Fixes to try
- Clean the screen and dry your hands, then remove the protector and retest.
- Unplug the charger, or try the original charger and cable.
- Restart the device and install system updates.
- On Windows touch laptops, the Tablet PC Settings control panel has a Calibrate option for pen and touch input.
- If one strip stays dead after all of this, the digitizer is likely damaged and needs repair.
Common questions
- Why does touch work with my finger but not with gloves?
- Capacitive screens need a conductive contact. Normal gloves insulate your finger. Touchscreen gloves have conductive fingertips, and some phones offer a glove mode that raises sensitivity.
- Can a screen protector cause ghost touches?
- It usually causes missed touches, not ghost touches. A protector with trapped water or dirt along the edge can occasionally trigger false input, though.
- Is a dead strip along the edge covered by warranty?
- If the device has no physical damage, a non-responsive area is usually treated as a hardware fault. Cracks and liquid damage are typically excluded, so document the condition of the glass when you contact support.