| 摘要 |
PURPOSE:To obtain a composite type speaker with ease of composite, thin thickness at low cost and high efficiency, by providing a piezoelectric element constituting a tweeter at a prolonged part of a voice coil forming a woofer. CONSTITUTION:The piezoelectric element 51 forming the tweeter is coupled to the upper end of the woofer voice coil bobbin 42, and an electric signal is given to positive/negative electrodes from leads 57, 58. Thus, the element is not vibrated in a low frequency sound where the impedance of the element 51 is high and the entire oscillating system is vibrated uniformly as the woofer. The woofer cone paper does not follow up because of a weak strength at middle and high sound frequencies, and the piezoelectric element 51 starts oscillation since the impedance is small. Further, it is not required for the cone paper of the woofer to provide much strength because no high frequency sound is required owing to the presence of the tweeter and the weight is made light. Thus, the efficiency of the woofer and the tweeter is high, and the speaker with broad band and high efficiency is attained. Further, the light weight is attained because of less number of component, and low cost and thin thickness are also attained. |
