| 摘要 |
A position sensor includes a drive circuit 51 to apply and excitation pulse to an excitation winding 29. The decay time constant of the current loop formed by the excitation circuit and winding is longer in duration than the excitation pulse. The long decay time enables current to flow in the excitation winding for an amount of time after the pulse. This means shorter pulses, and hence less power, can be used. The sensor may be used in a x-y digitising tablet having a resonant stylus 41 which interacts with the excitation windings. Sensor windings 31, 33, 35, 37 may be located in the tablet or in the stylus which generate an output signal corresponding to the position of the stylus. The sensor may also be used behind the display of a hand-held electronic device such as a personal digital assistant (PDA), mobile telephone or web browser. |
