| 摘要 |
An ultrasonic length measuring apparatus measures the number of times of crossing of the waveform of an ultrasonic wave signal with the threshold value, detects the crossing timing at, for example, the waveform having the maximal amplitude after a predetermined number of times counting from a crossing point crossing first, measures the time period from the transmission start of the ultrasonic wave by the transmission unit to the detected crossing timing and calculates the length based on the time measured. A coordinate inputting apparatus comprises a pen for transmitting an ultrasonic wave and a coordinate inputting apparatus for inputting coordinate positions of the pen based on a propagation time of the ultrasonic wave transmitted by the pen and received by a plurality of ultrasonic wave receivers and the receiver comprises at least a pair of ultrasonic receivers for receiving the ultrasonic wave transmitted by the pen and a clip mechanism for pinching a corner of a sheet. Malfunctioning due to the sound of collision generated by the contact of pen by delaying the transmission timing of the signal from the pen-shaped mover.
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