| 摘要 |
It is an object of the invention to provide a coordinate input apparatus which can eliminate an input point erroneously inputted. Values of voltage of pairs of electrodes (31, 32); (33, 34) of a tablet (24) are sampled at time t1 by A/D converter circuits (41, 42) to obtain values of X and Y coordinates of a latest input point. A coordinate predicting circuit (43) finds a predicted point of an input point of one period ahead from the coordinates of the latest input point and the input point at time t0 of one period before. The predicted point of the input point at time t1 is find in advance when the input point at time t0 is obtained. An erroneous input discriminating circuit (44) finds an error of the coordinates of the latest input point and the predicted point with respect to X- and Y-axis directions. When the error of the coordinates is less than an allowable error both in X- and Y-axis directions, the input point is determined to be valid and the coordinate of the input point is supplied to a buffer (47) as it is. When the error of the coordinates is the allowable error or more, the input point is determined to be invalid and (0, 0) is supplied to the buffer (47). <IMAGE> |
