| 摘要 |
PURPOSE:To ensure the sound reproduction without producing the nonlinearity of force even with a reduced major input, by securing a linear proportion for the relationship between the driving force and an input regardless of the position of a cylindrical conductor (coil). CONSTITUTION:An edge of a diaphragm 12 is fixed to a frame 11. A driving part 13 joined to the diaphragm 12 includes a magnetic circuit 24. A pierced hole 25 is provided at the center of a center pole of an under-plate 21 constituting the circuit 24. The circuit 24 has a magnetic gap 26 between a plate 23 and the center pole. A conductive cylinder 27 functioning as a coil is set into the gap 26 and then adhered to a center support rod 28 piercing through the center of a magnetic pole. At the same time, bearings 29 and 30 are set at both ends of the rod 28 to assure free revolution of the rod 28. In addition, the center edges of helical springs 31 and 32 are fixed to the rod 28. With such a constitution of the part 13, the number of chain crosses of magnetic flux has always no change since the relationship between the coil and the magnetic field has no change by the position. As a result, a constant driving force can always be obtained to eliminate the distortion of the driving force. |
