A constant offset is a calibration or resolution problem; a dead zone is a hardware problem. Test with a mouse: if the pointer moves normally, the computer is fine and the fault lies in the touch panel or its driver.
Procedure
Plug in a mouse
If the pointer moves and clicks register, the system and the display are fine: the fault is confined to the touch layer and its driver.
Clean the panel and remove any film
On a capacitive screen, a film of grease, a thick protector or a puddle of water create zones that stop responding. Wipe dry with the screen off, then try again before touching any software.
Recalibrate, but only on a resistive panel
An identical offset across the whole surface usually comes from resolution or scaling: check those first. Calibration applies only to resistive panels, since a capacitive panel does not need it. If the manufacturer provides a calibration utility, run the full procedure without skipping a target.
Check resolution and scaling
A display resolution different from the panel’s native resolution, or an unusual display scaling, shifts the touch point in a regular way. Restore the native resolution before calling it a failure.
Reinstall the touch driver
A system update can replace the manufacturer’s driver with a generic one. Reinstall the terminal manufacturer’s driver, restart, then recalibrate if the panel is resistive. A dead zone that survives this step is a hardware case.
Check these before calling support
- A mouse works normally on the same station.
- Calibration has been redone in full, with the screen at its native resolution.
Useful terms
- Capacitive or resistive touchscreen
A capacitive touchscreen is a screen that senses the conductivity of a finger: it is precise and supports multi-touch, but ignores a thick glove.
- Driver and firmware
The driver is the software that lets a device talk to the operating system; the firmware is the software embedded in the device itself.
- All-in-one terminal
An all-in-one terminal is a point-of-sale station that packs the computer, the touchscreen and the power supply into a single chassis.