Slightly strange but logical one. We recently used a Dell E2014T 20 inch E-Series Touchscreen on a job. Worked fine until we got it on site and then the screen’s touch accuracy went haywire. On-screen buttons didn’t activate and some areas of the screen caused the touch area to seemingly warp and cause false cursor positioning.
We noticed a slight pattern to the ‘warping’, mostly to the left but also in a strange diagonal. We fired up a paint program and drew lines across the screen to reveal the distorted areas. The ‘ah-ha!’ moment was when we realised the screen was an optical touchscreen. The ‘OptiPlex’ system uses a series of infra-red lights and detectors located around the edge of the screen. By placing your finger on the screen, it breaks several of the beams and your finger’s location can be triangulated.
The distorted lines you can see in the image above is evidence of the screen going ‘wonky’ along definite diagonals. On closer inspection, there were small specs of sawdust in the screen border. A quick squirt of compressed air and the screen was back to normal.
Also, if you’re planning to use this monitor (or a lot of low-cost touchscreens like the the Mimo Magic Touch series) on a Mac, you’ll probably have a issue finding a driver. Apple just don’t seem to support any touchscreen standards. The only 3rd-party drivers we’ve managed to get to work are from Touchbase. They cost money but it may be the only option.