AUTOMATIC DETECTION METHOD FOR RESONANCE FREQUENCY AND ITS DEVICE

摘要

PURPOSE:To obtain an efficient and exact detection method for resonance frequency and provide an automatic resonance frequency detection device with small size and good operation capability. CONSTITUTION:A synthetic oscillator 41 firstly automatically produces a coarse oscillation frequency signal VS within the frequency range set by a CPU 1 and oscillates a material 30 by way of a speaker 32. By detecting the maximum signal of the response signal SR from a sensor 31 detecting the displacement of the material 30, the CPU 1 defines the frequency corresponding to it as a coarse detecting resonance frequency fr. Then, within the predetermined frequency range in front and back of the coarse detection resonance frequency fr, a voltage control oscillator 43 automatically produces a fine oscillation signal VS and obtains a redetection resonance frequency to define it as the resonance frequency fc of the material 30. If a phase check signal generator 20 adds the response signal and the positive phase and negative phase of the oscillation frequency signal at the resonance frequency fc and compares the levels, then the phase of the response signal SR is simultaneously detected.