Wearable Computing

Headmounted Displays

In many applications of wearable computing it is necessary that the equipment allows the use of one's hands freely. That means, if any kind of display is involved, it cannot be held in the user's hand but must be located elsewhere. The most natural way of locating such a device, of course, is right before the eye. This gives reason for the idea of headmounted displays. The project in this field is on one hand related with the design of the displays and on the other with applying them to wearable computers.

The biggest project concerned with the task was to create a display integrate to the gear for detecting land mines by soldiers. This provided many challenges concerned with flexible usability in harsh surroundings and safety of the user.

The final display prototype is located on the soldier's helmet behind the visor. A rubber case should protect the forehead from crucial damage in case of accident and the optics are arranged in a way, that possible violation of the eye could be restricted to minimum. This optical system is rather simple using a lens, a mirror and a beam splitter. The lens should focus the displayed image to a distance comfortable for the user and the beam splitter is intended to enable both viewing the screen and the surroundings. One bigger problem of the prototype designing was the question of appropriate contrast. As the minefield can be located under bright snow as well as in a dark forest, it was chosen two polarisation filters, which can be twisted against each other. So the intensity of the light passing the beam splitter can be adjusted. In addition the device is supposed to work properly within a temperature range from -50 to +50 degrees centigrade.

In addition, several other display types were also developed for different virtual reality applications and for the wearable equipment. One current project is to develop an interface between a PC VGA output the Kopin Cyper Display 320 C, so this very small and high-standard device is usable for further applications.

The coming challenges in design and development will be decreasing the size of headmounted displays and to find a kind of socially acceptable shape so that they can be used in everyday life.

Soldier's Helmet

Mine-Detector-Display

Another Display-Design

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Updated , Hokkanen Mirja