Ancon Ltd v ACS Stainless Steel Fixings Ltd

Patent claims must be construed objectively through the eyes of the skilled person, using the claims, description and drawings together. Construction is purposive, but the function or purpose of an invention cannot replace the language chosen by the patentee. A patentee may claim less than the invention teaches or enables.

Where claims require a fixing head to have a generally elliptical cone shape, that expression retains the essential feature of an ellipse. It does not extend to every differently shaped head that produces a similar camming effect. A product lacking that essential claimed feature does not infringe, even if it obtains substantially the same technical benefit.

Ancon was the proprietor of European Patent (UK) No 0882164 for a channel assembly used for heavy-duty building fixings. It alleged that ACS’s 31/21 channel assembly infringed claims 1–12. ACS denied infringement and counterclaimed that the patent was invalid for anticipation, obviousness and insufficiency, relying principally on Dennis and Sandwith.

The central infringement issue was the construction of the expressions generally elliptical cone shape and forced against the lips of the channel. The court also considered whether the prior art anticipated or rendered obvious the claimed assembly.

1. Construction. Patent claims are construed objectively by asking what the skilled person would understand the patentee to mean. The court must read the claims in the context of the specification and drawings, consistently with Article 69 of the EPC and its Protocol. The construction is purposive rather than mechanically literal, but purpose and technical function are aids to meaning, not substitutes for the language of the claims.
2. Meaning of the claimed shape. The phrase generally elliptical cone shape described each of the three embodiments and retained an essential elliptical characteristic. The word generally accommodated truncation, flattened portions and other modifications shown in the patent, but did not remove the requirement for an identifiable elliptical form. The claims therefore did not cover every bolt head having curved, inclined surfaces capable of producing the same camming action.
3. Infringement. ACS’s bolt head was not generally elliptical in shape. Although it produced substantially the same camming benefits in a similar V-shaped channel, it lacked the essential claimed feature. The infringement claim therefore failed. It was unnecessary to decide the alternative construction of the phrase forced against the lips.
4. Validity. On the adopted construction, the insufficiency case fell away. Dennis did not disclose an elliptical cone or the relevant conical face and therefore did not anticipate claims 1, 3 or 6. It also provided no realistic or obvious route to the claimed bolt head or camming effect. Sandwith disclosed a different system and did not suggest a generally elliptical cone-shaped head. The validity attack accordingly failed.
5. The unjustified-threats counterclaim, being dependent on infringement and validity, was adjourned for later determination.