JPS6454525A - Coordinate input device - Google Patents

Abstract

PURPOSE:To decrease a reflected wave in the peripheral part, and to improve the detection accuracy at the time of detecting a vibration, by installing plural vibration- proof materials whose acoustic impedances are different, to the peripheral part of a vibration transfer plate. CONSTITUTION:A coordinate on a vibration transfer plate 8 of a vibration pen 3 is detected by measuring a transfer time of an ultrasonic vibration which has been transferred to a vibration sensor 6 through the transfer plate 8 from the pen 3. To the peripheral part of this transfer plate 8, a vibration-proof material 7 is installed, and the vibration-proof material 7 is constituted by installing a vibration-proof material 7-1 whose acoustic impedance is large, and a vibration-proof material 7-2 whose acoustic impedance is small, to the outside, and the inside, respectively. According to such a constitution, a reflected wave E by the first boundary surface becomes small by the acoustic impedance, and a comparatively large reflected wave F is generated by the second boundary surface, but the vibration is absorbed and decreased by the vibration-proof material 7-2. A reflected wave G by the third boundary surface shows a larger level, but until it reaches the third boundary surface, and by going and returning after it has been reflected thereby, the vibration is absorbed and decreased by each vibration-proof material. Accordingly, the reflected wave generated in the peripherals part decreases as a whole.