| 摘要 |
PROBLEM TO BE SOLVED: To make preventable the variations in length of an end insensitive zone caused by a delay by providing a flaw detecting probe with a material end detecting function. SOLUTION: Most of ultrasonic wave is transmitted from a transmission probe 4 to a receiving probe 5 when a material 1 does not exist because the ultrasonic wave is not intercepted by the material 1. On the occasion, the height of echo is regarded as 100%. When the material 1 exists, the ultrasonic wave is intercepted by the material 1, so that little echo is received. When the material 1 intercepts half of the probe as an intermediate state, the echo becomes half of the echo obtained when the material 1 does not exist. This condition is defined as a time of judgement of the existence of the material 1. That is, a height of 50% echo is regarded as a threshold value, and the transmission probe 4 and the receiving probe 5 are provided with the self-recognition function for starting the detection when the height of echo is less than 50, and stopping the detecting when it is over 50%, which prevents the variations in length of an end insensitive zone between a channel and the material 1, and dispenses with an end detecting probe. |
