| 摘要 |
<p>A portable radio communications device (1) has a display (6) on which a position indicator (7) can be positioned, and means (8) for controlling the position of the position indicator (7) on the display (6) manually by a user. The controlling means comprise an optical emitter adapted to illuminate an object through a translucent and moisture-proof surface; an optical detector adapted to detect changes in light reflected from the object due to the movement thereof; and circuitry for generating a control signal for the position of the position indicator (7) in dependence on the changes in reflected light. The optical detection of the movement of a finger provides a very easily operated control device with no need to press the finger against the device, and thus forces on the printed circuit boards are avoided. The moisture-proof surface ensures that the device is insensitive to dirt and moisture.</p> |
