| 摘要 |
PURPOSE:To reduce the distortion due to a high frequency current flowing to a voice coil inserted in the magnetic gap and to make the assembly of a speaker easy, by constituting the magnetic circuit for speaker with sintered carbon steel. CONSTITUTION:At the external circumference on a lower end of a pole yoke 1, a back plate 2 is projected, a ring shape magnet 3 is fitted on the back plate 2, a top plate 4 is fixed on the upper surface of the magnet 3 and a magnetic circuit of a speaker is constituted. A voice coil is inserted between the inner circumference of the top plate 4 of the magnetic circuit and the upper end external circumference of the yoke 1. The yoke 1 of the magnetic circuit is formed with carbon steel, which is heated for a given time at a given temperature, and after heating, sintering treatment is made with sudden cooling. Further, a minor loop produced from a current flowing to the voice coil near the operating point A on a magnetization curve of the magnetic circuit is made smaller than the minor loop near the operating point B conventionally, allowing to reduce the distortion due to the high frequency current flowing to the voice coil. |
