Coordinate input device

Abstract

Abstract PURPOSE:To calculate a coordinate position specified by a position specifying means as the delay time of a plate elastic wave beyond a detection time point by allowing a detecting means to detect the zero-cross point of a signal generated by a differentiating means. CONSTITUTION:A desired position on a coordinate input board is specified and the input board is actuated to generate the plate elastic wave. The plate elastic wave is received and the envelope of an electric signal corresponding to its intensity is differentiated twice to detect its zero-cross point and obtain a signal of propagation delay time, which is processed by an arithmtic control part 6 to calculate the coordinate position. The zero-cross point of the 2nd differentiated waveform has a larger gradient than the 1st detection point and the detection is performed with higher accuracy. Namely, a waveform received by a sensor 1a is amplified by an amplifier 16 and the envelope is detected by an envelope detecting circuit 17 and differentiated twice by differentiating circuits 18 and 19. The 1st zero-cross point of this waveform is detected by a detecting circuit 20 and sent to the arithmetic control part 6 to compute the coordinate position.

Inventors

• 👤 Kiyoshi Kaneko
• 👤 潔 兼子
• 👤 Atsushi Tanaka
• 👤 淳 田中
• 👤 Yuichiro Yoshimura
• 👤 雄一郎 吉村

Bibliographic Details