| 摘要 |
PURPOSE:To ensure safety through prevention of output of an excessive ultrasonic wave by a method wherein when the peak value of a square computing output exceeds a set value, excitation of an ultrasonic probe is stopped. CONSTITUTION:A current by means of which an ultrasonic probe 5 is excited is detected in the shape of a voltage through a resistor R2, and electrically insulated by a transformer T2 to transmit it to a subsequent stage. The detecting current is squared by a squaring device 21 to obtain an exciting current square value, which is brought into an amount equivalent to acoustic intensity Im is defined to maximum intensity, ISPTA to space peak time average intensity, and ISPPA to space peak pulse average intensity. Three kinds of the intensity are determined from the exciting current of a ultrasonic probe, and compared respective specified voltage values, and when exceeding the specified voltage value, a high voltage used for exciting the ultrasonic probe 5 is shut off. Even when external noise is mixed and abnormality and a trouble occur, only an acoustic output within given specified value is emitted from the ultrasonic probe, resulting in the possibility of safe diagnosis. |
