| 摘要 |
PROBLEM TO BE SOLVED: To suppress generation of side lobe.SOLUTION: A coil 100 provided in a diaphragm vibrates back and forth on the basis of an acoustic signal, when the acoustic signal is supplied. Since the upper width is wider than the lower width in an air gap 70 where the coil 100 is located, the magnetic flux density on the upper side becomes smaller than the magnetic flux density on the lower side. Since a force acting on the coil 100 becomes smaller above the air gap 70, compared with the lower side where the magnetic flux density is large, displacement of the diaphragm on the upper side becomes smaller than that on the lower side, and thereby the sound pressure of a sound generated on the upper side of the diaphragm becomes smaller than that generated on the lower side. When there is a difference in the sound pressure of a sound generated on the upper side and lower side of the diaphragm, the directivity characteristics are different from those when there is no difference.SELECTED DRAWING: Figure 6 |
