Screen coverage: A pen-interaction problem for PDA's and touch screen computers

Touch screens at electronic kiosk systems, pen based PDAs or smart phones, have become more popular over the recent years. The direct interaction on the display by fingers, hands or pens implies the problem of covering the screen. The coverage depends on the interface organization and the use of the interaction elements. This paper describes a basic approach of measuring the coverage of the interface, as well as determination and definitions of basic parameters concerning the ratio between visualization and interaction areas. The metric determination of the coverage leads to analytic testimonies and provides new predictions for resent and future usability tests.