The modern design of moving-coil drivers was established by Oliver Lodge in (1898)[2]. The moving coil principle was patented in 1924 by Chester W. Rice and Edward W. Kellogg.
The diaphragm is usually manufactured with a cone or dome shaped profile. A variety of different materials may be used, but the most common are paper, plastic and metal. The ideal material would be stiff (to prevent uncontrolled cone motions), light (to minimize starting force requirements) and well damped (to reduce vibrations continuing after the signal has stopped). In practice, all three of these criteria cannot be met simultaneously using existing materials, and thus driver design involves tradeoffs.