There are three types or “categories” of patents: plant, design and utility.
Plant Patent Application
A plant patent is granted to an inventor who has invented or discovered and asexually reproduced a distinct and new variety of plant, with some exceptions. The grant, which lasts for 20 years from the date of filing the application, protects the inventor’s right to exclude others from asexually reproducing, selling, or using the plant so reproduced. This is a narrow class of patents that applies to very few applicants.
Design Patent Application
In a design patent application, the subject matter which is claimed is the design embodied in or applied to an article of manufacture (or portion thereof) and not the article itself. The design for an article consists of the visual characteristics embodied in or applied to an article. I.e., a design patent protects the look of the article rather than any functionality or intended use of the article.
Design protection does not extend to properties that are required in order to allow for similar functionality. I.e., since a design is manifested in appearance, the subject matter of a design patent application may relate to the configuration or shape of an article, to the surface ornamentation applied to an article, or to the combination of configuration and surface ornamentation. Design is inseparable from the article to which it is applied and cannot exist alone merely as a scheme of surface ornamentation. It must be a definite, preconceived thing, capable of reproduction and not merely the chance result of a method.
Design patents usually have a fairly narrow scope of protection. I.e., other things that look similar but do not include all required elements are not infringing. There are some things that we can do to broaden this protection (e.g., change some solid lines in a drawing to dashed lines which make them optional rather than required).
Utlity Patent Application
In a utility patent application, the subject matter which is claimed is the structural elements which make up the invention. I.e., the parts of the invention and their connection to one another are the protected subject matter. Broadly speaking, the appearance of the article and its intended use are of no consequence in a utility application. However, there are ways to give patentable weight to functional aspects of some elements. Nevertheless, in most cases the functionality of the invention or portions thereof are not given patentable weight and similar products may preclude patentability.
Utility applications may be filed as either a provisional application or a non-provisional application. Which one is right for you is a business decision but some important considerations are discussed in another blog post.
Utility patents usually result in more broad protection than design patents. I.e., competitors that offer similar functionality are more likely to be infringing a utility application than a design application.
Which application is right for you?
The general rule is that if you are looking to protect the appearance of the invention you should file a design application. Otherwise, you should file a utility application. Filing one does not preclude filing of the other so if both are important to you, then both should be filed in order to maximize protection.