| 摘要 |
<p>PURPOSE:To provide a tablet device unified with a display which applies an active matrix drive method to detect coordinates without deteriorating the display quality. CONSTITUTION:The switches 6-11 switch and select the Y and X coordinate signal generating parts 3 and 5 during the detection of coordinates. Each of both parts 3 and 5 contains a single pulse generating circuit. This pulse generating circuit includes a differentiator, an inverter and a waveform shaper and inputs a gate clock signal and the TFT output signal sent from a liquid crystal driving TFT to generate a coordinate detection scanning pulse having the width shorter than the ON mode delay time of the TFT. This scanning pulse is applied successively to the gate electrode G and the source electrode S of a display panel 1 to scan these electrodes. Thus it is possible to prevent such a case where the TFT is turned on by the Y coordinate detection scanning pulse applied to the electrode G. Then the coordinates can be detected with no deterioration of the display quality.</p> |
