| 摘要 |
<p>A transducer signal waveshaping system is provided, in which a signal excitation circuit includes a non-linear device (18). The resulting circuit (10) produces a short input pulse, which allows a piezoelectric transducer (22) to transmit a shortened output signal having distinct waveshape characteristics. The resulting waveshaped output signal, typically an ultrasonic signal, provides a measurable time-dependent signal that is particularly suited for data entry systems, such as for movable transmitter pens (40) and white boards. The location of the transmitter pen (40) in relation to the writting area (112) of a white board (114) can be determined, using the periodic transmission of the waveshaped output signals. Alternative embodiments include additional circuit elements, which allow the resulting waveshaped output signal to include even more distinctive waveform features. The distinctive waveform features allow the transmitter pen (40) to be located even more accurately, and provide a means for transferring supplementary information, such as pen up vs. pen down distinction, and determined pen characteristics, such as pen color, pen line width, and pen user.</p> |
