| 摘要 |
<p>PURPOSE:To shorten the length of a line where a pulse wave flows and to reduce an interference radio wave in strength by arranging a high voltage pulse generating circuit nearby the ultrasonic oscillator. CONSTITUTION:A tablet on which the position of a transmission pen is evaluated by utilizing an ultrasonic wave from the ultrasonic oscillator 12 is formed. A signal for determining the period of electric power and a trigger is supplied to the high voltage pulse generating circuit which consists of a transistor (TR) 15, inductor 13, inertia current diodes 16 and 18, etc., for driving the oscillator 12 from a power circuit 11 through a cable 24. Consequently, said ultrasonic wave oscillator 12 is applied with the current I2 of the inductor 13, obtained by turning on and off the electric power from the power circuit 11 through the TR15, as high-voltage pulses, thereby shortening the length of the line where a high- frequency and large-amplitude pulse wave flows. Further, an arithmetic circuit 5 calculates and measures the position of the transmission pen.</p> |
