You've finally created a really unique but practical chair - something that would look perfect in the pages of Architectural Digest. You're also savvy enough to realize you should look into protective legal steps before unveiling it to the public (and rival designers). So you'll just apply for a standard patent, right? Well, not exactly. It's a common assumption that there's one general application process to have a patent granted. In fact, there are actually three types of patents (utility, design and plant) each with a distinct path for obtainment.
Not too many people are mistaken about whether their invention qualifies for a plant patent (which protects new varieties of - you guessed it - plants). But it's easier to confuse whether an invention qualifies for a design patent or utility patent, and it's important to decide this issue at the beginning of your search for protection. That's because applying for a patent typically involves considerable investments of time and money.
Under U.S. patent law, a utility patent protects "any new and useful process, machine, article of manufacture, or composition of matter, or any new and useful improvement thereof." A design patent protects a "new, original, and ornamental design for an article of manufacture." In short, utility patents protect the way something is made and used; design patents protect the way something useful looks.
If you've come up with a new type of engine (a machine), engine part (manufactured article) or an improved way of manufacturing engine parts (a method), then you're more likely looking for a utility patent. On the other hand, if your invention lies in the uniquely formed shape of a car's hood and fenders, then (assuming this new shape doesn't also improve the way the car works) you probably need a design patent.
Another example of an invention eligible for a utility patent is a jacket that contains an improved insulation system. A jacket whose invention lies completely in the unique curves of its lapels would better qualify for design patent protection. While the first invention improves the use of the jacket (keeping the user warm), the second invention is a design change that does not alter overall function.
There are a number of other differences between utility and design patents beyond appropriate subject matter and scope of protection. These include possible application types, required application elements, the examination process and length of patent terms. For more information on utility patents, see link.
Inventions typically qualify for only one type of patent. In rare cases, an invention will qualify for both types of protection, or for both design patent and copyright protection (and sometimes even trademark as well). Either way, you should be clear on what type of patent you are applying for because of the important differences between them.