1963 年 19 巻 6 号 p. 255-262
When magnetic or dielectric circuits exist in the electromechanical energy conversion of reciprocal electroacoustic transducers, the mechanical impedance z in the transducer equation for the system includes a negative stiffness. In this paper, it is pointed out that the vector power consumed as negative stiffness constitutes a part of magnetically consumed vector power. Then, in the calculation of electromagnetic and electrostatic transducers, the mechanically consumed vector power should be given by the power consumed by purely mechanical impedance which is obtained by subtraction of negative stiffness from the impedance z. In the electrodynamic transducer, there is no change in the polarizing magnetic field, because driving current and/or mechanical vibrations of the diaphragm have no effect on the field. The negative stiffness in this system become zero, and z in the equation equal to the pure mechanical impedance z_m. As a result of this consideration, the relation of the vector powers in the reciprocal transducers are shown as follows : EI^^^-+Fv^^^-=Z_eI^2+E^<'2>/(Z^^^-_r)+z_mv^2 for electromagnetic transducers, EI^^^-+F^^^-v=Y^^^-_eE^2+I^<'2>/(Y_r)+z^^^-_mv^2 for electrostatic transducers; EI^^^-+F^^^-v=Z_eI^2+0+z^^^-_mv^2 for electrodynamic transducers, where the first term of the right side denotes electrically consumed vector power, the second term magnetical one, and the third mechanical one respectively. It is also stated that the expression of mechanical vector power depends on the type of transducers and from this point of view a new classification of transducers is proposed in Fig. 11.