| 摘要 |
PURPOSE:To make a faithful detection possible with a high S/N by arranging divisionally an oscillation detecting coil and synthesizing respective detection signals from coils through corresponding delay circuits and transmitting them to a discriminator to select plate waves having a specific mode from propagated plate waves. CONSTITUTION:Signals similar to plate wave waveforms are induced in detecting coils 19a-19d and are supplied to delay circuits 20a-20d. Each signal is delayed by a time set by a delay controller 22 and has the same phase and is sent to an adding circuit 21. Signals Da-Dd are added in the adding circuit 21 to generate a wide-amplitude signal A having a spread similar to that of plate waves, and this signal A is sent to a discriminator 14 through an amplifier 13. The discriminator 14 discriminates the attenuation quantity and the propagation time of plate waves on a basis of this signal and discriminates finally properties of a sample plate body 16. Thus, the resolution is improved, and the oscillation is great, and therefore, the S/N is improved to make accurate discrimination possible. |
