| 摘要 |
PURPOSE:To detect oscillation acceleration with high sensitivity without decreasing the efficiency of a speaker nor a high limited reproduction frequency by feeding a signal from a piezoelectric element as a control signal back to the input signal of the speaker. CONSTITUTION:The piezoelectric element 11 is joined between the outer circumference of a voice coil bobbin 12 and a coupler ring 13 is joined to a diaphragm 1. Consequently, when force is generated at the bobbin 12, the cylindrical element 11 is applied with pressure in a shearing direction by the mass of the diaphragm 1 and a signal proportional to the pressure is generated between a terminals 3a and 4a. This signal is proportional to the acceleration of the diaphragm 1 and usable as the control signal. Consequently, large additional mass is unnecessary, so the oscillation acceleration is detected with good sensitivity without lowering the efficiency of the speaker nor the high limited reproduction frequency. |
