Best Practices for Design Patents- Use of Solid vs. Broken (Phantom) Lines

By Debby Winters

As we already discussed in this series of blog posts about design patents, the solid lines in the figures of a design patent application function to define the scope of the invention. Broken (sometimes called phantom) lines may be used to show the environment in which the article is used, but do not form a part of the invention. Therefore, if a product includes all the features shown in solid lines in a design patent, but not the features shown in broken lines, that product still infringes that design patent. Similarly, if a prior art reference shows the features in solid lines but not the broken lines of a design, that prior art reference can still anticipate the design patent application. An application that includes broken lines should include a paragraph in the specification indicating that the broken lines are for illustrative purposes only and form no part of the claimed design.

In addition, broken lines may be used to broaden the scope of the design patent in a continuation application. For example, a continuation application may convert originally disclosed solid line structure to broken lines. Since it is the solid lines that function to define the scope of the invention, replacing solid lines with broken lines necessarily broadens the scope of the design patent. Again, the importance of using an experienced draftsperson cannot be overemphasized.