| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To suppress dispersion of errors of coordinate values of an ultrasonic type pointing device. <P>SOLUTION: This coordinate value input system is provided with: a first calculation processing part 191 using, as reception confirmation timing, timing at which a voltage value converted from ultrasonic waves received by an ultrasonic receiver R1 first passes either a threshold voltageγandψfor calculating a first period from the transmission timing of the ultrasonic waves to the reception confirmation timing; and a second calculation processing part 192 using, as reception settlement timing, any point of time after the voltage value has passed the threshold voltageγorψto a predetermined number of times X and until it passes the threshold voltageγorψnext time for calculating a second period from the transmission timing to the reception settlement timing as an ultrasonic wave propagation time. The second calculation processing part 192 changes the predetermined number of times X according to the first period. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
