Bringing Tactile Feedback to an In-Air Screen

In-air touchscreens have been seen before – usually featuring a projector and water vapour (Display Monitor Vol 20 No 1, Vol 21 No 17). However, there has been little sensation of feedback. A team at the University of Tokyo, however, has developed a new way to present such a display. Although a screen is used, users are not allowed to touch it – bypassing the problem of oil, dirt and germs gathering on the unit.

An LCD display is located at the bottom of the system, face up, showing a video that will eventually be visible to the user; for instance, an ATM pinpad. The video reflects off an aerial imaging plate – a 2D array of corner reflectors – to present a ‘floating’ image to a user.

The clever bit is to ‘trick’ users into thinking that they are touching a screen – even though there is nothing there. The image appears in the middle of an infrared sensor grid, which tracks finger position. A phased array ultrasound transducer, at the top of the system, responds by sending a beam of ultrasound to that area. As a result, the user has the impression of physical contact. Various sensations can be created, from the feel of wind to a rigid surface.

A video ( shows that accuracy is raised when using the transduscer, as opposed to operating the same system without it.