In patent claims, means-plus-function language may initially seem to broadly encompass various ways to achieve a function. However, under 35 U.S.C. § 112, ¶ 6, the scope of these limitations is restricted to specific embodiments disclosed in the patent specification, along with their equivalents. This can make means-plus-function claims narrower than they appear.
Understanding the Scope of Means-Plus-Function Language
For example, a generic term like “fastener” might broadly include items like nuts, bolts, screws, and hooks and loops. However, if a claim specifies “means for fastening” and the specification only describes nuts, bolts, and screws, the scope of the claim would not extend to hooks and loops, as they are not disclosed in the specification. This limitation means that while “means for fastening” may sound broad, it could actually restrict the scope compared to simply using the term “fastener.”
Identifying Means-Plus-Function Language without the Term “Means”
Although including the word “means” generally signals means-plus-function language, sometimes courts interpret claims as means-plus-function limitations even without the term “means.” This interpretive approach was illustrated in Massachusetts Institute of Technology (MIT) and Electronics for Imaging, Inc. (EFI) v. Abacus Software, where the patent’s claims did not use the term “means” but included limitations that the court interpreted as means-plus-function.
Case Overview
MIT and EFI, the assignee and exclusive licensee of U.S. Patent No. 4,500,919 (the ‘919 Patent), held a patent on a color processing system for producing copies. The ‘919 Patent included two specific limitations in its claims:
- “Colorant selection mechanism”
- “Aesthetic correction circuitry”
MIT and EFI alleged that Microsoft Windows infringed their patent claims. Although neither limitation explicitly used “means,” the Federal Circuit examined each to determine if they were means-plus-function limitations.
Federal Circuit’s Analysis
The Federal Circuit addressed each limitation individually:
- “Colorant Selection Mechanism” Interpreted as Means-Plus-Function
The court held that “colorant selection mechanism” should be treated as a means-plus-function limitation because:- Generic terms like “mechanism,” “means,” “element,” and “device” usually lack sufficient structural specificity.
- The patentee used “means” and “mechanism” interchangeably in the specification.
- At least one dictionary equates “means” with “mechanism”, reinforcing the structural ambiguity of “mechanism.”
- The phrase “colorant selection” lacked a clear structure both in the specification and in standard dictionary definitions.
- “Aesthetic Correction Circuitry” Interpreted as Structural
Conversely, the Federal Circuit found that “aesthetic correction circuitry” was not a means-plus-function limitation due to:- The dictionary definition of “circuit” implying sufficient structure.
- Prior Federal Circuit cases holding that “circuit” with a function denotes structure.
- The understanding within the art that “circuit” refers to hardware, providing clear structure even if broad.
The court also clarified that “circuit” denotes hardware and does not include software in this context, thus further supporting its interpretation of “aesthetic correction circuitry” as a structural term.
Key Takeaways from MIT v. Abacus Software
- Generic Terms and Means-Plus-Function Language: Terms like “mechanism,” “element,” or “device” may trigger means-plus-function interpretation if they do not specify a particular structure.
- Structural Terms: Words like “circuit” imply structure and do not invoke means-plus-function language, especially in technical fields where “circuit” is commonly understood as hardware.
- Hardware vs. Software Distinction: In this case, the term “circuit” was limited to hardware, reinforcing the need to specify the structure clearly in the claim.
These insights highlight the importance of carefully choosing language in patent claims to ensure accurate interpretation and enforceability. For guidance on using means-plus-function language or drafting claims to maximize protection, feel free to reach out to me at (949) 433-0900. As a patent attorney serving Orange County, Irvine, Los Angeles, San Diego, and surrounding areas, I’m here to help clarify claim strategies and strengthen patent applications.