JPS648430A - Coordinate input device - Google Patents

Abstract

PURPOSE:To attain an accurate coordinate input by determining the coordinates of an input point based on time information obtained up to the leading and trailing zero crossing timing of a waveform of a detecting signal during the increment of the amplitude of the detecting signal. CONSTITUTION:Vibration from a vibrating pen 3 is inputted to a vibration transmitting plate 8, transmitted as a plate wave and detected by three vibration sensors 6. Output signals from the sensors 6 are inputted to an arithmetic control circuit 1 as timing information through a waveform detecting circuit 9. The circuit 9 is driven through a level comparator only during the increment of the level of an input signal and pulses having a prescribed width is outputted to the circuit 1. The circuit 1 finds out time values tp, t'p up to the leading and trailing zero crossing timing of the final pulse, calculates a distance between the vibration input point and each sensor by combining these time values and determines coordinate information from the distance information.