COORDINATE INPUT DEVICE, COORDINATE INPUT METHOD, ULTRASONIC WAVE DETECTION DEVICE, AND ULTRASONIC WAVE DETECTION METHOD

PROBLEM TO BE SOLVED: To provide a coordinate input device for precisely detecting a coordinate of a coordinate input means even if noise occurs. SOLUTION: The coordinate input device 200 is provided with a microphone 101 receiving an ultrasonic wave transmitted from an input pen 210, an adjacent pulse determination circuit 300 determining whether pulse width of a pulse signal based on the ultrasonic wave received by the microphone 101 is within a range of prescribed reference pulse width or not, determining whether a pulse interval of the pulse signal based on the ultrasonic wave received by the microphone 101 is within a range of a prescribed reference pulse interval or not and removing a pulse in the pulse signal as noise in accordance with determined results and a microcomputer 105 detecting the coordinate of the input pen 210 based on the pulse signal from which noise is removed in the adjacent pulse determination circuit 300. COPYRIGHT: (C)2005,JPO&NCIPI