Ultrasonic inspection apparatus

Claim 1

In an apparatus for inspecting a test piece and indicating an unacceptable condition therein, including means for transmitting a test signal into said test piece, for receiving an associated response signal reflected back thereto, and for generating a defect signal when the character of said response signal indicates an abnormal condition in said test piece; means for moving said transmitting-receiving means relative to said test piece; means for generating a control signal at each of a plurality of predetermined intervals of distance of said movement of said transmitting-receiving means; means for pulsing said transmitting-receiving means to sequentially generate test signals at a frequency independent of generation of said control signals; and principal counter means for counting said controls signals in response to generation of defect signals and being reset to an initial value in response to the absence of generation of defect signals, said principal counter means further producing an alarm signal when it accumulates a count of said control signals that exceeds a preset amount in response to generation of sufficient defect signals during said movement of said transmitting-receiving means over a predetermined distance to confirm the presence of an abnormal condition that is unacceptable; the improvement comprising: reset counter means connected (1) to said transmitting-receiving means for receiving defect signals therefrom; (2) to said control signal generating means and being reset to an initial amount upon receipt of any one defect signal but counting control signals in the absence of receipt of defect signals and producing a reset signal when the accumulated count equals a predetermined amount indicative of the maximum distance of movement of said transmitting-receiving means during which a defect signal may not be generated from an unacceptable abnormal condition; and (3) to said principal counter means for conducting a reset signal thereto; whereby said principal counter means is reset by said reset signal when said reset counter accumulates a count equal to said predetermined amount indicating that defect signals have not been generated during movement of said transmitting-receiving means over a distance equal to said maximum distance and whereby said principal counter means accumulates a count of control signals as long as said reset counter receives at least one defect signal before accumulating a count equal to said predetermined amount.