Smartphone Screen Lets You Reach Out and Touch Some Thing

Northwestern University researchers have developed a phone add-on that gives physical feedback

A tiny startup outside Chicago has created external hardware for a smartphone that enables a user to feel as well as see an image on flat glass. The user has the sensation of touching keys on a keyboard, for example.

The company, called Tanvas, is selling its $2,000 TPad phone, a standard Motorola Moto G coupled with haptic technology, which creates the illusion of touching physical textures and shapes displayed on its screen. “This is a new medium; a new way to display information,” says Joe Mullenbach, a Northwestern University Ph.D. candidate and one of two developers of the TPad, or tactile pattern display, phone.

A crude version of a haptic interface already comes with smartphones in the form of vibrations that alert you to an incoming call or text message in place of a ring tone. “Everything today is audio, visual or both, but people actually get a lot of information from tactile experiences,” Mullenbach says.

The TPad looks almost exactly like a Moto G snuggled in a protective case. Tanvas’s black hardware weighs 50 grams, most of which is the plastic-and-glass housing. A plate of glass covers the phone’s screen, and the plastic housing surrounds the rest. The haptics hardware requires relatively little power—about the equivalent of playing the Moto G’s speakers at full volume.

The technology works by tricking the brain into feeling something that doesn’t exist, not unlike the way a television fools the eye into perceiving motion. A tiny actuator in the housing makes the glass resonate at 38.7 kilohertz, an ultrasonic frequency that cannot be heard or felt. Tanvas’s algorithms analyze images on the Moto G’s screen, and the phone calculates where over the screen the user’s finger is positioned. These data are translated into ultrasonic oscillations that create the illusion of something physical.

The ultrasonic waves repel a fingertip from the glass. Larger-amplitude waves impede contact, making the screen feel slippery. Smaller amplitude oscillations allow more contact and therefore produce more friction.

There might, for instance, be an image on the screen of a roadway rumble strip that conveys a bumpy sensation to warn a driver not to drive out of a lane. A finger running over a valley in the strip would experience little friction and easily slide to an area that generates more friction, which would be sensed as one of the ridges in the rumble strip.

The TPad is capable of simulating smooth and raised shapes, abrupt edges and curved lines. Bas-relief images on, say, a coin can be faithfully represented. A scanned page’s words and images might be made to feel as if they were on a raised surface.


Author: Jim Nash