| 摘要 |
PURPOSE:To reduce the interference attenuation of a reflected wave by changing the phase of an ultrasonic wave during the time of its transmission in a single frequency. CONSTITUTION:A transmission time signal from a trigger circuit 1 is supplied to frequency dividers 13, 14, a counter 16 and the reset terminal R of a data selector 17, and thereby the reset of each circuit is released during a time when the transmission time signal is present. Meanwhile, an output signal of an oscillation circuit 8 serves a trigger for a phase shifting circuit 12, making it operate. The phase shifting circuit 12 delivers from the output terminals Q and Q' of a multivibrator 11 and output having the same frequency and duty ratio with those of the output of the aforesaid oscillator 8 and an output having the same frequency therewith and the different duty ratio therefrom, and ithey are supplied as clocks of the frequency dividers 13 and 14 respectively. Accordingly, by designing data in the data selector 17 to be switched over over a binary output of the counter 16, an output having a different phase is obtained and transmitted as an ultrasonic wave through the intermediary of a transducer 2c. |
