Coordinate detecting device, writing instrument, and coordinate inputting system

摘要

A pen includes a first speaker that outputs a first signal and a second speaker that outputs a second signal. The first and second speakers are located away from a tip of the pen at respectively different locations. The second signal is delayed with respect to the first signal by a time shorter than a cycle of the first signal. An interpolation time is set between the times of generation of the first and second signals. Interpolated positions of the first and second speakers at the interpolation time are estimated, and position of the tip of the pen is calculated from the interpolated positions of the first and second speakers.