| 摘要 |
<p>PURPOSE:To obtain a cordless tablet device which never malfunctions owing to noise, etc., by shortening the supply time of a current supplied to a coil wound around the core of an input pen to about 20musec. CONSTITUTION:When the core 1 of an input pen is pressed against in one of detection loops arranged in X-axis and Y-axis directions among corresponding sense loops 10 for selecting some item entered in a tablet input board with the input pen, a current (I) is fed to a coil 2 for about 20musec. Then, an electromagnetic induced voltage E' is generated at a sense loop 10 and then amplified by sense amplifiers 11 and 21, and the resulting signal is binary-coded by digital encoders 12 and 22 into a plus pulse signal, which is converted by a succeeding circuit which is not shown in the figure into code signals for showing X and Y coordinates. Outputs of said encoders 12 and 22, on the other hand, are supplied to an AND circuit 30 to send strobe pulses which show a signal from the input pen to a processing unit which is not shown in the figure.</p> |
