| 摘要 |
The invention concerns the use of light sources such as light emitting diodes (LED's), combined with a standard optical sensor such as a rapid photodiode or photo-transistor to detect positions designated by the user by means of a device similar to a pencil or pen. The invention is particularly applicable to small-size portable devices for which an alphanumerical keyboard or a two-dimensional position defining device is required, such as portable telephones for example. |
