Touchscreen interfaces may make our lives easier, but the things do tend to get smeared with finger oil and whatnot, plus they're notorious for spreading germs. That's why a team of researchers at the University of Tokyo, led by assistant professor Yasuaki Monnai, have developed the HaptoMime. It's an ATM-like interface that lets the user feel like they're touching a glass screen, when in fact they're touching nothing at all.

Here's how the system works ...

An LCD screen lies face-up on the bottom of the setup, displaying the interface video – this could be a numeric keypad, a menu board of icons, or anything else. Sitting at a 45-degree angle above that screen is an aerial imaging plate (AIP), which is a sort of two-way mirror.

When the user views that plate from the front, they see the LCD screen reflected through it. The illusion, however, is that the screen is hovering parallel to them at the front of the HaptoMime, instead of lying flat on its back at the bottom. It looks like they could reach in and touch the projected display, even though their finger would actually just pass right through to the AIP.

In order to make it seem like they're touching the display, the HaptoMime incorporates a grid of infra-red sensors and an ultrasound phased array transducer. The sensors first detect the location of the user's finger, as it enters the interface area. The transducer then responds by sending a focused beam of ultrasound to that area. As a result, the user's sense of touch is stimulated when their finger appears to reach the screen.

Additionally, by comparing the location of the user's finger to the layout of the interface on the LCD, it's possible for the user to actually ... well, to actually use the interface. As can be seen in the video below, they're able to drag and drop icons, play piano keys, and draw pictures.

Ultimately, it is hoped that the technology could be used to allow people with wet or dirty hands to access computers without messing up the screen, and to limit the spread of disease through interfaces used in public places.

A paper on the research was presented earlier this month at the ACM Symposium on User Interface Software and Technology, in Hawaii.

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