| 摘要 |
<p>PURPOSE:To prevent the deterioration of the precision of position detection due to noise of higher harmonics by preventing a first frequency for coordinate detection and a second frequency for illuminator lighting from being coincident and preventing the higher harmonics of the second frequency from being included in the pass band of the first frequency. CONSTITUTION:Position data consisting of X and Y direction data which are instructed to be next are inputted to an electronic computer 900, are sequentially stored in a display memory 501, are read and outputted to X, Y direction drivers 503 and 504. Then, they are synchronized with the timing pulse of a controller 502, and a scanning pulse which a scanning pulse generator 505 generates is inputted. Respective drivers 503 and 504 input position data to a panel 50 and a position instructed by a pen on the sense part 10 is displayed on the same position on the panel 50. When a back light 60 is lighted, an invertor 600 operates and noise due to the higher harmonics of a clock signal CK 2 occurs. But, the frequency of the higher harmonics of the signal CK 2 does not coincide with a clock signal CK 1 and it is not included in the pass frequency band of BPF 307.</p> |
