PIEZOELECTRIC RECEIVER CIRCUIT

摘要

PURPOSE:To make the frequency characteristic of a magnetic field force flat by connecting a capacitor in parallel with a magnetic field generating coil, branching a voice signal current to the capacitor so as to cause a constant voice signal current to flow to the magnetic field generating coil. CONSTITUTION:A voice signal current (i) is branched to a magnetic field generating coil 1 as a current i1 and to a capacitor 4 as a current i4, and since the current is small in a frequency where the impedance of the circuit 4 is high, the current i1 flowing to the magnetic field generating coil 1 is less than the case not connected with the capacitor 4 at a high frequency. The current i1 flowing to the magnetic field generating coil 1 is made nearly constant at the voice frequency band by selecting the impedance of the capacitor 4 with respect to the impedance of the magnetic field generating coil 1 and the impedance of the piezoelectric receiver 2 properly.