Zipher Ltd v Markem Systems Ltd & Anor

A court may enforce an unconditional undertaking given by counsel to limit patent claims, even where the undertaking was not recorded in the order. The relevant place to establish the undertaking is the transcript.

Following amendment of the Patents Act 1977, the discretion to refuse an otherwise allowable amendment is limited by relevant European Patent Convention principles. Conduct-based objections do not generally justify refusal, although abuse of rights or process may be restrained.

For insufficiency, the patent must enable the claimed invention without undue burden. A broad class must be enabled across its scope, and a combination of defects may cumulatively render a specification insufficient.

Zipher brought infringement proceedings concerning patents for tape drives and thermal transfer printers. Markem denied infringement and sought revocation of the patents.

Zipher also sought to amend patent 602. Markem contended that the amendment breached an unconditional undertaking given during earlier entitlement proceedings, and raised added-matter, discretion, novelty, inventive-step and insufficiency objections.

The principal issues were whether the undertaking was binding, whether the amendments were allowable, whether the patents were valid, and whether the accused printers infringed if the relevant claims were valid.

1. Undertaking. Zipher had given an unconditional undertaking to the court to limit the relevant claims to no more than claim 5 if it retained them. The undertaking took effect when given. Its omission from the order did not prevent enforcement. Zipher was therefore precluded from pursuing broader amendments to patent 602.
2. Amendment discretion. Section 75 of the Patents Act 1977, as amended, required regard to relevant European Patent Convention principles. The former broad discretion, including consideration of the patentee’s conduct and state of mind, was materially limited. Subject to procedural fairness and abuse of rights or process, a proper and timely amendment necessary and appropriate to the proceedings should ordinarily be allowed.
3. Construction and validity. “Monitoring tension” required monitoring a variable indicative of tension, not merely something bearing on what might happen to tension. The claims did not require monitoring while the tape was moving. Adjustment could be made through one motor or both. Claims 2 and 3 introduced impermissible intermediate generalisations by providing for tension control without monitoring.
4. Prior art. The Adkin Memorandum had not been shown to have been made available to the public because there was no proof that the former employees remained aware of its information when released from confidentiality. Datamax did not anticipate the claims as construed, but claims 1 and 6 would lack inventive step over Datamax with a variable-rate spring. The claims were not obvious over IBM, Shroff, Ikenaga, Wolff or Markem.
5. Insufficiency. The patents did not adequately teach how to obtain the work-related current needed to monitor tension with stepper motors. The erroneous tension equation, temperature effects and other defects reinforced the conclusion that the specification imposed a research burden and did not clearly and completely disclose how to perform the invention. Patent 375 was additionally insufficient because it expressly suggested an inadequately explained alternative current-measurement method.
6. Disposition. The amendment application failed. Patent 602 was invalid for insufficiency and remained so even if amended. Patent 375 was invalid for insufficiency. If valid, the relevant claims would have been infringed by the SmartDate 5 EV and LV, and specified claims by the Series 18.