Background
Kitagawa Industries owned Japanese Patent No. 7,207,706, entitled “Magnetic Shielding Material.” Following a patent opposition, the company amended the patent by deleting claims 2–4 and 7 and revising claims 1, 5, and 6. Claim 1 covered a shielding material having a magnetic layer and a single aluminum conductive layer, with the conductive layer having a thickness of 6.5–50 μm “according to the frequency band of the electromagnetic waves to be shielded.” Claims 5 and 6 added limitations concerning the magnetic layer.
The Japan Patent Office accepted the amendments but cancelled claims 1, 5, and 6. It concluded both that claim 1 lacked inventive step over an earlier disclosure and that the amended claims failed the clarity requirement. Kitagawa sought judicial cancellation of the JPO decision, challenging both grounds.
The Court’s Holding
The Intellectual Property High Court dismissed Kitagawa’s action and upheld cancellation of claims 1, 5, and 6. It held that the phrase requiring a conductive-layer thickness “according to the frequency band of the electromagnetic waves to be shielded” made claim 1 impermissibly unclear under Article 36(6)(ii) of the Patent Act. Because a frequency band is defined by upper and lower frequency limits, the court reasoned that the claim did not permit a reader to determine whether a particular layer thickness corresponded to the relevant band unless those limits and their relationship to thickness were identified.
The specification did not cure the defect. Although Figure 3 reported shielding performance for aluminum layers of 6.5, 11, and 30 μm, it did not establish whether any particular thickness within the claimed range corresponded to a frequency band bounded by specified upper and lower limits. Nor could labels on packaging, product numbers, or QR-code information supply the missing certainty: claim scope must be determined from the claims in light of the specification and drawings, and objectively identical products could not move into or out of the claim merely because of external labeling. The same defect applied to dependent claims 5 and 6.
Because the clarity violation independently required cancellation, the court did not decide whether the JPO’s inventive-step analysis was correct. It ordered Kitagawa to bear the litigation costs.
Key Takeaways
- A claim tying a physical parameter to a “frequency band” must provide enough information to determine the band’s upper and lower limits and how they correspond to that parameter.
- Experimental data for selected embodiments will not necessarily clarify the full claim scope when it does not define the claimed relationship across the range.
- Packaging, product codes, or QR-code disclosures cannot cure uncertainty in patent scope, particularly when identical products could be classified differently based only on external labeling.
Why It Matters
The decision underscores Japan’s requirement that third parties be able to determine claim scope from the patent itself. Functional language such as “according to” a target operating range may be indefinite when the claim and specification do not supply an objective method for deciding whether a product satisfies that relationship.
It also illustrates that a reviewing court may uphold a JPO cancellation on clarity alone without reaching a separately contested inventive-step ground when resolving that dispute could not change the outcome.