| 摘要 |
PURPOSE:To attain the fine reproduction of a low sound and also to increase the rigidity and to reproduce the fathfulness by amplifying the small amplitude of an oscillation source such as a voice coil by a mechanical amplifying means such as a lever and transmitting the amplified oscillation to a diaphragm. CONSTITUTION:When a reproducing signal current is applied into a voice coil 14 of which lower end part is inserted into a magnetic gap, driving force is generated by Fleming's left hand rule and the voice coil 14 is vertically oscillated. The oscillation is transmitted to the bent part (a) of a center supporting part 15 and the end part of the inner periphery of the 1st quadrilateral cylinder 16 is also vertically oscillated. At that time, the 1st and 2nd quadrilateral cylinders 16, 20 are rotationally reciprocated around the end part of the outer periphery of the 2nd quadrilateral cylinder 20 while bending and extending so that their diagonal length is changed. Then, an periphery supporting part 18 coupled with the peripheral edge of the quadrilateral cylinder 16 through a bending part (b) is vertically oscillated and a diaphragm 12 fixed on the supporting part 18 is vertically oscillated, so that sound is generated. In this case, the displacement of the diaphragm 12 coupled with the supporting part 18 is expanded by the ratio of the diagonal dj of the 2nd quadrilateral cylinder 20 to a value jf obtained by subtracting the diagonal length of the 2nd quadrilateral cylinder from the diagonal length of the 1st quadrilateral cylinder 16 as compared to the displacement of the voice coil 14.
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