A Sticky Touch Screen Lets You Feel the Buttons
mikejuk sent one in that sends absolute shivers up my spine. "I have a problem with sticky touch screens — whenever I try to clean the jam off I activate and use a lot of apps I never intended to. However it looks as if sticky is the way of the future. A prototype screen has been shown that varies the friction as you move your finger across it. The result is that you can 'feel' the buttons and notches on scroll bars. It sure beats having to build real buttons..."
Did you read the article? While this isn't the same as a raised button, it is definitely a form of tactile feedback. I think the biggest issue with this form though is that it only appears to work for one finger.
TFA indicates that the screen vibrates to create a thin layer of air between the finger and the screen. That results in low friction. When the finger "touches" a button, the vibration stops, the finger "touches down on" the screen and the friction increases, telling the finger and the brain that a button (or a notch on a scroll bar, etc.) has been reached. That differs from currently-widely-available haptic feedback because the vibration is in the screen itself and not the entire device.
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