Edison is a tough example because many of his patents were on ideas that were invented in parallel or pre-dated by an inventor in Europe, Joseph Swan.
The key to preparing good claims in a utility patent is isolating the novelty of the invention in your independent claims.
All sorts of shapes, sockets, and filament materials were tried for years in making a lightbulb that would endure, with little success. Some filaments worked better than others, but all of them burned out too quickly. Some sockets were easier to use when changing the light bulb. If Edison is the first one to determine that a filament in a vaccuum will burn exponentially longer than a filament exposed to air, the independent claims should not specify the type of socket, the shape of the bulb, or the material used to make or coat the filament. It should be a filament in a bulb attached to a socket, wherein the socket and bulb form an air tight enclosure encapsulating the filament. The dependent claims should focus, at least in part, on how to attach the socket and bulb to form an air tight seal.
Answered on Dec 04th, 2013 at 9:25 AM