End-user devices are increasingly designed with a reduced form factor as a primary goal, to reduce weight, bulk, and in many cases, costs. End-user devices that display information, however, have a competing need to provide a display that is legible to a user with average eyesight, limiting how small a display on such a device can be. In some cases, the display becomes a gating factor of the overall size of the device. Wearable devices, such as a watch, that are intended to be worn on a specific part of a human body inherently have very limited space for a display.
In addition to the display, devices often require a mechanism for the user to indicate to the device what information is desired to be viewed. Often one or more physical selection mechanisms, such as buttons, are provided on the device to implement a user interface that facilitates user interaction with the device. Such selection mechanisms must be of a sufficient size that they can be manipulated by a human finger, which again limits the extent to which the device can be reduced in size. This problem can be minimized by implementing only one or two buttons on the device, but this solution requires the user to memorize complex button sequences to initiate different commands. Such user interfaces are often perceived by users as difficult to use, because the complex button sequences are easily forgotten.
Accordingly, it would be desirable to minimize, to the extent practical, the size of a display of a device, and yet still maintain an intuitive user interface for controlling the display of information on the device.