Method and apparatus for inputting coordinates

Abstract

A coordinates input apparatus for detecting coordinate values of an arbitrary point by indicating the arbitrary point on a vibration transmission plate by a vibration input pen for generating a vibration, comprises: a plurality of sensors, arranged at predetermined positions in the vibration transmission plate, for detecting the vibration generated by the indication by the vibration input pen, for converting the vibration into electric signals, and for outputting; a measuring circuit to measure delay times from a time point when the arbitrary point has been indicated by the vibration input pen until time points when the electric signals are detected; an obtaining circuit to obtain origin correction data from a plurality of points on the vibration transmission plate; a memory to store the origin correction data; and a processor for reading out the origin correction data from the memory, for correcting the coordinate values on the basis of the delay times measured by the measuring circuit and the origin correction data, and for calculating the coordinate values. The processor has a selector to select the origin correction data of the optimum point so as to execute the optimum coordinate value correction from the origin correction data obtained from the plurality of points and stored in the memory.