DeviceCheck Pro

Touch screen test

Find dead zones by painting every square, and check how many fingers your screen can track at once. Best done full screen, with the case and protector removed.

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How capacitive touchscreens sense your finger

Under the glass is a fine grid of transparent electrodes. Your finger conducts, so touching the glass changes the tiny electric charge stored where row and column electrodes cross. The controller scans the grid many times a second and works out the centre of every disturbed patch, which is why several fingers can be tracked at once and why gloves, very dry skin or a thick protector weaken the signal.

A dead zone happens when part of that electrode grid or its connection is damaged, typically after a drop or pressure on the screen. Because the grid runs in lines, faults often show as a whole strip that doesn’t respond, rather than a single spot.

Tips for accurate results

  • Use full-screen mode so the edges and corners are included; they fail first on many phones.
  • Swipe slowly in overlapping rows. Fast flicks can skip squares even on a healthy screen.
  • Pressure only shows on devices and browsers that report it; most phone touchscreens report a fixed value.

Checking a display for bad pixels too? Try the dead pixel test.

Still not working? Describe it

An AI assistant suggests likely causes and fixes, cheapest first. It sees only what you type. Answers can be wrong; check your device maker’s support pages before opening anything up.

Questions

How do I test my touchscreen?

Use “Paint the grid”: drag your finger across the whole screen until every square is filled. Squares that stay dark after you have swiped over them several times mark a dead zone. Then use the multi-touch pad with several fingers to check how many touches the screen tracks.

How many touch points should my screen support?

Most phones and tablets track 5 to 10 simultaneous touches. Windows touch laptops usually report 10. The page shows the number your browser reports (maxTouchPoints) alongside the most touches you actually managed.

Parts of my screen don’t respond. Is it hardware?

Remove the case and screen protector first; a lifted protector edge is a very common cause. Clean the screen, restart, and test again. A dead zone in the same spot every time, especially after a drop, points to a digitizer fault.

The screen registers touches I didn’t make (ghost touches).

Unplug the charger and test again: cheap chargers can inject electrical noise. Check for moisture and a damaged protector. Ghost touches that continue on battery with a clean screen usually need a digitizer repair.

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