| 摘要 |
PURPOSE:To detect cracked elements surely with simple operation and easy judgement of defectives and non-defectives by producing stress forcibly in the inside and detecting the sound from cracks. CONSTITUTION:A detector 2 has a sound detector 3 mountable to a package 1 contg. a pellet 1' which is an object to be detected, an amplifier 4, a high-pass filter 5 and a display device or deciding device 6. A circuit of the pellet 1' is constituted so as to be applied with voltages E1, E2. If a switch 7 is turned on to apply voltage to the pellet 1', the pellet evolves heat by itself and generates thermal stress. If a microcrack is produced in the pellet, the crack is progressed by the thermal stress and a sound is produced at this time. This sound is detected by the detector 2, by which the presence or absence of the crack is decided visually or by the deciding device. Only the crack progressing vibration discriminated from external vibrations is detected by the filter 5. It is equally well to utilize the on sgnal of the switch 7 for the trigger signal of the display device 6. |
