INPUT UNITED TYPE LIQUID CRYSTAL DISPLAY DEVICE AND COORDINATE DETECTING METHOD

摘要

PURPOSE:To improve the precision of coordinate detection and reduce the influence of an external noise as to the input united type liquid crystal display device which detects voltages, applied to an X electrode and a Y electrode of a liquid crystal display, through a pen. CONSTITUTION:This device consists of a liquid crystal panel 101, a column circuit 102, a common circuit 103, the pen 119, a display controller which performs display control in a display period and generates data for X-coordinate detection in a blanking period, an X-coordinate detecting circuit and a Y- coordinate detecting circuit equipped with integrating circuits which convert signals generated by detecting voltage variations of X and Y electrodes of the liquid crystal panel through the pen 119 into digital signals, and a coordinate detection control circuit which detects X and Y coordinates from the output signals of the X-coordinate detecting circuit and Y-coordinate detecting circuit and outputs them. Consequently, a coordinate position on the display screen that the pen comes into contact with can precisely be detected by utilizing the driving electrode of the liquid crystal panel 101 and the influence of the external noise is reducible.