GRAPHIC DATA ACQUISITION AND PROCESSING METHOD AND DEVICE

摘要

Ultrasonic pulses are emitted by two transmitters (12, 14) carried on an instrument (10) and substantially aligned with the tip thereof. A plurality of receivers (62a, ..., 62e) occupy predetermined positions relative to a base (50) on which a line is drawn with the tip of the instrument, such that the ultrasonic pulses emitted from any point on the base surface are received by more than two receivers. The ultrasonic pulse propagation times between each transmitter and the receivers are measured to determine the co-ordinates of the vector defined by the positions of the two transmitters, and thereby deduce the position of the instrument tip on the base, and at least one of the two instrument orientation data items consisting of the longitudinal tilt of the instrument relative to the base and the angular position of the instrument about an axis which is at a predetermined angle to said base. Furthermore, the pressure exerted on the base by the instrument tip is sensed in order to determine line width data on the basis of the orientation data and/or the pressure data, and instrument tip position data is combined with corresponding line width data.