Alan Nuttall Ltd v Fri-Jado UK Ltd & Anor

Patent claims must be construed by giving their words their natural meaning in the context of the specification. Context informs construction, but does not justify ignoring or substantially altering the language used. A claim requiring outlets over a substantial length of a duct is not limited to outlets above a particular shelf unless the claim says so. Nor does air fail to be drawn from a chamber merely because it is entrained indirectly by another airflow. A design may infringe even though it performs the invention less effectively or in a different direction from the preferred embodiment. Obviousness is primarily a matter for the trial judge. An appellate court should intervene only where a properly directed judge reached a plainly untenable conclusion. A patent is not insufficient merely because it extends to a design which the skilled person can readily implement, although the specification does not describe that design as preferred.

Alan Nuttall Ltd appealed from the judgment of Mr Peter Prescott QC, sitting as a deputy judge in the Patents Court, which held that Fri-Jado UK Ltd and Fri-Jado BV’s Multi-deck Mark 2 cabinet infringed the patent and that the patent was neither obvious nor insufficient. The patent concerned a heated, open-fronted food display cabinet using two connected but separate airflow systems: one to warm the food and one to create an air curtain.

The appeal challenged the findings on infringement, obviousness and insufficiency. The central issues were whether the Mark 2 satisfied claim 1 despite having no outlets in part of the duct and using an upward rather than downward air curtain, whether the obviousness findings could be disturbed on appeal, and whether the patent was insufficient or lacked fair basis because the claim extended to the upward-curtain design.

1. Appeal dismissed. The trial judge had correctly found infringement, absence of obviousness and absence of insufficiency.
2. Claim 1 involved two separate, although interconnected and not wholly independent, airflow circuits. The claim’s two flow-inducing means performed different functions. This understanding was supported by the claim language, the specification and the evidence.
3. The phrase “a plurality of outlets over a substantial length of the duct” bore its ordinary meaning in context. It did not require outlets in any particular part of the duct, such as above the top shelf. Omitting outlets from a limited portion did not prevent the remaining portion from being a substantial length. Construction could not be used to introduce a limitation which the claim did not contain. A less effective implementation could still infringe.
4. The requirement that the second flow-inducing means draw air from the upper end of the chamber was satisfied. Air in the Mark 2 was drawn into the ascending airflow indirectly. Indirect entrainment did not deprive the process of the character of drawing air from the upper part of the chamber.
5. On obviousness, the judge had directed himself in accordance with Pozzoli SPA v BDMO SA & Moulage Industriel de Perseigne [2007] EWCA Civ 588. Obviousness was primarily for the trial judge. The appellate court would not interfere unless the conclusion was plainly untenable. Neither Guibert nor Detwiler, nor the asserted common general knowledge, made the claimed two-fan arrangement obvious. Detwiler was materially different in its two-door, two-curtain context.
6. The insufficiency and fair-basis arguments failed without resolving the wider law on fair basis or so-called Biogen insufficiency. The skilled person would have had no difficulty applying the patent’s teaching to an upward-curtain cabinet. A design’s lack of preference in the specification did not exclude it from the claim or invalidate the patent.

• Court of Appeal (Civil Division): Appeal dismissed.
• High Court of Justice, Chancery Division (Patents Court): Mr Peter Prescott QC, sitting as a deputy judge, held that the patent was infringed and that the patent was neither obvious nor insufficient: [2008] EWHC 1311 (Pat).