DISPLAY DEVICE PROVIDED WITH COORDINATE INPUT FUNCTION

摘要

PURPOSE:To prevent deterioration of the resolution of a tablet by cancelling the induced signal of the tablet affected by noises to perform the second scan after catching the timing of the noise signal produced from a display part through a coordinate detecting part. CONSTITUTION:A display control circuit 1 supplies the signals to a segment driver 3 and a common driver 4 for display on a liquid crystal panel 2 and also supplies the frame signal to a coordinate detecting circuit 5. The X and Y scan circuits 7 and 8 scan successively the sense lines on a tablet and obtain the coordinate detecting signal by the electromagnetic conduction with an energizing coil 9. The noise signal is synchronous with the rise of the frame signal and gives effects to the coordinate detecting signal. The circuit 5 incorporates an MPU and the frame signal is supplied to the interruption input terminal of the MPU. Then the MPU performs successively the scan and invalidates the scan of the timing by which an interruption is produced since this timing contains the impulsive noises. Then the same scan is carried out in the next timing.