From the US Patent & Trademark Office:
Definition of a Design
A design consists of the visual ornamental characteristics embodied in, or applied to, an article of manufacture. 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. A design for surface ornamentation is inseparable from the article to which it is applied and cannot exist alone. It must be a definite pattern of surface ornamentation, applied to an article of manufacture.
In discharging its patent-related duties, the United States Patent and Trademark Office (USPTO) examines applications and grants patents on inventions when applicants are entitled to them. The patent law provides for the granting of design patents to any person who has invented any new, original and ornamental design for an article of manufacture. A design patent protects only the appearance of the article and not structural or utilitarian features.
Types of Designs and Modified Forms
An ornamental design may be embodied in an entire article or only a portion of an article, or may be ornamentation applied to an article. If a design is directed to just surface ornamentation, it must be shown applied to an article in the drawings, and the article must be shown in broken lines, as it forms no
part of the claimed design. A design patent application may only have a single
claim (37 CFR § 1.153). Designs that are independent and distinct must be filed in separate applications since they cannot be supported by a single claim. Designs are independent if there is no apparent relationship between two or more articles. For example, a pair of eyeglasses and a door handle are independent articles and must be claimed in separate applications. Designs are considered distinct if they have different shapes and appearances even though they are related articles. For example, two vases having different surface ornamentation creating distinct appearances must be claimed in separate applications. However, modified forms, or embodiments of a single design concept may be filed in one application. For example, vases with only minimal configuration differences may be considered a single design concept and both embodiments may be included in a single application.
The Difference Between Design and Utility Patents
In general terms, a “utility patent” protects the way an article is used and works (35 U.S.C. 101), while a “design patent” protects the way an article looks (35 U.S.C. 171). Both design and utility patents may be obtained on an article if invention resides both in its utility and ornamental appearance. While utility and design patents afford legally separate protection, the utility and ornamentality of an article are not easily separable. Articles of manufacture may possess both functional and ornamental characteristics.
Improper Subject Matter for Design Patents
A design for an article of manufacture that is dictated primarily by the function of the article lacks ornamentality and is not proper statutory subject matter under 35 U.S.C. 171. Specifically, if at the time the design was created, there was no unique or distinctive shape or appearance to the article not dictated by the function that it performs, the design lacks ornamentality and is not proper subject matter. In addition, 35 U.S.C. 171 requires that a design to patentable must be “original.” Clearly a design that simulates a well-known or naturally occurring object or person is not original as required by the statute. Furthermore, subject matter that could be considered offensive to any race, religion, sex, ethnic group, or nationality is not proper subject matter for a design patent application (35 U.S.C. 171 and 37 CFR § 1.3).