Apparatus and method for ultrasonic measuring of length for coordinate input

Abstract

A coordinate detection apparatus used, for example, to input handwriting to a computer. The apparatus measures the number of times of crossing of the waveform (55) of an ultrasonic wave signal over a threshold value (Vth), detects the crossing timing at, for example, the waveform having the maximal amplitude (W4) after a predetermined number of times counting from a crossing point of a first crossing, measures the time period from the transmission start of the ultrasonic wave by the transmission unit (10) to the detected crossing timing and calculates a length (L) based on the time measured. A coordinate inputting apparatus (100) comprises a pen (102) for transmitting an ultrasonic wave and a coordinate inputting apparatus for inputting coordinate positions of the pen (102) based on a propagation time of the ultrasonic wave transmitted by the pen (102) and received by a plurality of ultrasonic wave receivers (304) and the receiver comprises at least a pair of ultrasonic receivers (304-1, 304-2) for receiving the ultrasonic wave transmitted by the pen (102) and a clip mechanism for pinching a corner of a sheet. Malfunctioning due to contact noise between the pen and sheet can be avoided by delaying the transmission timing of the signal from the pen.

Description

technical field [0001] The present invention generally relates to an ultrasonic length measuring apparatus and method for measuring length by calculating the propagation time of ultrasonic waves, and, more particularly, the present invention relates to coordinate input of handwriting created by handwriting characters or numbers on paper with a special pen as characters Apparatus and method for ultrasonic length measurement of data and graphical data. Background technique [0002] A mouse, a trackball, and a magnetic or pressure-sensitive type tablet, etc. are known as coordinate input devices (pointing devices) for inputting coordinate information to a computer. Among these devices, magnetic or pressure-sensitive writing tablets are excellent in terms of usability and precision. It is a pointing device that, when a magnetic or pressure-sensitive type sensor plane is traced with a pen-type mover, is used to detect coordinate positions traced on the sensor plane and output th...

AI Technical Summary

Problems solved by technology

However, when such a conventional technique of applying triangulation is used, a blind area is generated in a part of the paper, and there arises a problem that input of coordinates becomes impossible, or even if input is possible, the resolution is thereby lowered

In addition, there arises a problem of larger equipment size and increased cost

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