Invention Grant
US07750894B2 Coordinates input system, coordinates input method, coordinates input program, and computer-readable storage medium 有权
坐标输入系统,坐标输入法,坐标输入程序和计算机可读存储介质

Coordinates input system, coordinates input method, coordinates input program, and computer-readable storage medium
Abstract:
A first arithmetic section is provided that calculates a first time, which is a time period from a transmission timing of a ultrasonic wave to a reception recognized timing at which a wave height value of the ultrasonic wave received by an ultrasonic wave receiving section crosses a predetermined threshold for a first predetermined number of times. A second arithmetic section is provided that calculates a second time as the propagation time of the ultrasonic wave, the second time being a time period from the transmission timing of the ultrasonic wave to a reception confirmed timing, which is a timing after the wave height value has crossed the predetermined threshold for a second predetermined number of times and before the wave height value crosses the predetermined threshold again, wherein the second arithmetic means varies the second predetermined number according to the first time. In this way, coordinates of a pointing device employing ultrasonic wave can be obtained with less error variation.
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