A speaker diaphragm 10 is provided having an improved quality of radiation
sounds and a good outer appearance. The speaker diaphragm has in its
slanted area projections typically represented by a peak line 4 and
recesses typically represented by a bottom line 5. The projection
typically represented by the peak line extends radially from the central
area to the edge portion, and curves along the circumferential direction
as it comes near to the edge portion. While the speaker diaphragm 10
vibrates at a large amplitude and moves toward the bottom side thereof, a
rotation force is applied to air which is likely to concentrate upon the
central area to thereby lower the air pressure to the central area. The
speaker diaphragm 10 has a three-dimensional structure like a screw
propeller so that the mechanical strength of the speaker diaphragm 10 can
be increased over the whole area thereof and division vibrations can be
suppressed. The speaker diaphragm is manufactured by ejection molding of
material containing polypropylene as it main composition so that a variety
of colors can be easily used during manufacture processes. In cooperation
with the unique structure like the screw propeller, a strong visual
impression is given.
