Nobuhiko MASUI*, Tetsuo OKAZAKI** and Yoshinobu TONOMURA*
*NTT Cyber Solutions Laboratories, ** NTT Software Corporation 1-1 Hikarinooka Yokosuka-Shi Kanagawa 239-0847 Japan
Personal Digital Assistants (PDA) are becoming essential private and business tools but their displays remain rather small. Moreover, their operating systems are limited. Obviously, they should allow the user to efficiently view a large amount of information within a limited time. An information display method that efficiently displays a large amount of information in a small display area and excels in visual recognition and ease of operation is thus essential. In addition, new PDA applications could be developed if a new information display method were developed that could efficiently display complex information. We propose and evaluate such a method for the user interface of PDA's. Our assumptions are an A5 size color display with about 640*480 pixels. Chapter 2 introduces the new method and a realization technique. Chapter 3 describes the experiment used to clarify the performance of this method, and experiment results are discussed. Chapter 4 provides examples of suitable applications for this method.
There are three methods for displaying a large amount of information: the scroll method, the multi-window method, and the overlay method. The scroll method demands frequent scrolling to refer to all information. The multi-window method occludes information lying underneath a window. Therefore, window switching is needed to view all information.
The overlay method tries to visually combine information on two or more separate layers and is often used in CAD and mapping systems. The overlay method can display a large amount of information in a small display area simultaneously. However, the existing overlay method suffers from 3 main problems: information occlusion, insufficient identification, and weak linkage between layers or objects.
We have extended the overlay method to create a new display method suitable for efficiently displaying complex information in a small display area. The method alters the visual attributes of the information on each layer as is described below.