Head-mounted computers like Google Glass are a useful way to view content and interact with the world on the move, but one drawback is the lack of a physical interface on which the user can click, drag or navigate content.

Japan's NTT DoCoMo showed a prototype technology at Japan's Ceatec exhibition this week that aims to fix that.

The technology essentially takes any paper surface – a sheet of writing paper or the page of a book – and with the tap of a finger turns it into a display before your eyes. I got to try out the technology during a demonstration at the show.

DoCoMo's prototype glasses are a clunky affair, designed for engineering tests rather than consumers. They have two clear lenses through which I could see the world. The navigation system works with a small motion-sensing ring, worn on the finger you'll be navigating with.

I reached down and picked up an ordinary paper notebook, but when I tapped on its cover with my finger the outline of a display appeared. Tapping again brought up a simple interface that looked like it had been projected on to the notebook.

From there, I could navigate menu items by swiping icons on the notebook and tapping the ones I wanted to select. Tapping the movie icon played a movie, which appeared to be displayed on the notebook cover.

But the image was produced only in the glasses, and to anyone standing nearby it looked like I was tapping away on a blank page. To them I probably appeared slightly mad, but to my eyes it all made sense.

So instead of using voice commands or tiny buttons to control the display in the glasses, I could pick up something tangible instead. It also worked on a small pad of sticky notes, with the menu adapting to the size by showing one icon per screen instead of the grid I saw on the notebook.

Touching space

The interface is among a number prototypes for head-mounted displays being demonstrated by NTT DoCoMo, Japan's largest cellular operator.

A second, called the space interface, allows a person to manipulate virtual objects. In the demonstration, a virtual object hovered in front of me, and I could reach out my hands and pinch the sides and stretch it to make it bigger.

A small infrared camera on the glasses keeps track of the wearer's hands and interprets those movements to manipulate the object they appear to be holding.

A second demonstration of that technology allowed me to bounce an animated toy bear up and down on my finger. As it descended, I held my hand out to where it was falling and when it reached my finger it bounced back up. I could also bat it from side to side.

As with the first system, those nearby see nothing more than a person waving their hands in the air, but to the wearer it all makes sense.

AR with facial recognition

A third wearable technology used augmented reality to provide additional information about the world around. When a person approaches, the head-mounted device uses facial recognition to try to identify them, then projects their name and other details on a display.

So rather than scramble to remember someone's name, you can reply with a confident greeting and maybe a remark about the last time you saw them. It feels very futuristic and might raise concerns about privacy.

The same system can be used to translate text, on a restaurant menu for example. If you hold the menu up in front of you, the headset reads it and displays the translation.

All three technologies are research projects and there are no immediate plans to turn them into commercial products.