| 摘要 |
PURPOSE:To detect a minute sound pressure signal with ultrahigh sensitivity by providing a 1st ceramic resonator capacitor sensor circuit outputting a main sound detection signal and an operational amplifier amplifying a signal of the 1st ceramic resonator capacitor sensor circuit. CONSTITUTION:A 1st ceramic resonator capacitor sensor circuit 9a consists of an oscillation circuit 1 having a ceramic resonator, a main sound resonator 2 comprising other ceramic resonator than the ceramic resonator of the oscillation circuit 1 and a detection circuit 4. Then the detection circuit 4 applies envelope detection to an AM modulation signal from the main sound resonator 2 and converts the result into a signal corresponding to the sound pressure signal of the main sound and it is fed to an operational amplifier 12. The operational amplifier 12 amplifies the detection output signal and gives the result to a desired signal processing circuit for a loudspeaker or a recorder or the like. Thus, a weak sound pressure signal is accurately detected with high sensitivity. |
