| 摘要 |
<p>PROBLEM TO BE SOLVED: To recognize an inputting coordinate by calculating the arrival time of an ultrasonic signal by a digital multiplying processing or the like. SOLUTION: The frequency of an ultrasonic signal from an ultrasonic oscillator 1 is converted by a switch 2 so as to be transmitted from a speaker 4 incorporated in a coordinate input pen, and the transmitted sound is received buy each microphone 11 of receiving parts A and B provided at the right and left upper edges of a coordinate input board, then is amplified by an amplifying part 12, and digital-converted by an A/D converting part 13. Then, this signal is inputted to a multiplier 15, where it is multiplied by a cosine wave from a cosine wave memory 14, and inputted to a data processing part 18 after high frequency components are removed by an LPF 16. Then, the arrival time at the microphone 11 of the receiving parts A and B is calculated, thus an inputting coordinate is recognized.</p> |
