Federal Circuit Uses Reference Number Conventions In Claim Construction

On February 21, 2020, the Federal Circuit remanded Ironworks Patents LLC v. Samsung Elecs. Co. back to the Northern District of California due to its flawed claim construction below. The panel of judges found the term ‘camera unit’ to have been misinterpreted to require a battery and external interface device over the specification and convention of the reference numbering.

At issue for the camera unit was U.S. Pat. Nos. 6,427,078 directed to hand-held personal devices and the potential infringement of Samsung mobile phones. Because Samsung’s accused devices did not include a battery or external interface device, the lower court’s claim construction resulted in the two sides stipulating to non-infringement before Samsung took the construction to the Federal Circuit on appeal.

Ambiguity of the Claims

In their analysis of the term ‘camera unit’, the Federal circuit appropriately first looked to the claims themselves. Claim 1 provides that a ‘camera unit’ “comprises a camera, optics, means for processing and for storing, at least one memory unit, and an output”. Claim 36 provides a ‘camera unit’ as “having at least one memory unit.” Finally, claim 73 explains that the ‘camera unit’ “comprises optics, an image sensor, and means for processing and storing”. The various descriptions of the term in each independent claim led the Federal Circuit panel to the specification for clarity.

In Light of the Specification

The Federal Circuit found that the specification supported Ironworks’ construction excluding the battery and external interface from the camera unit. The specification “consistently refers to camera unit 14 which includes camera arrangement 14o (comprising camera 14a and optics 14b) and image processing unit 14c”.

Samsung argued that the description that “the structure of both camera card 15 and camera unit 14 conforms to the block diagram shown in Fig. 5” requires that everything shown in Fig. 5 must be included as part of the ‘camera unit’. The Federal Circuit was not persuaded:

“Figure 5 uses the same numbering convention as the rest of the specification, suggesting camera unit 14 is comprised of elements numbered as 14 (i.e., camera arrangement 14o, which comprises camera 14a and optics 14b, and image processing unit 14c). See ’078 patent at 4:25–29. Other elements in Figure 5 are numbered differently, such as battery 21 and interface 22, suggesting they are not part of the camera unit 14. See id. In fact, the description concerning Figure 5 explains that “camera card 15” (as opposed to “camera unit 14”) includes battery 21 and interface 22. Id. at 4:25–29. On the other hand, a camera unit as expressly defined in the specification includes a camera, optics, and an image processing unit.”[1]


In the instant case, the narrowed interpretation of camera unit increases the likelihood that Ironworks will win its infringement case for those claims. On a practical level, this emphasis on reference number convention emphasizes the need for consistent and clear drafting in the initial filings and the necessary attention to detail needed to adequately protect your innovations.

[1] Ironworks Patents LLC v. Samsung Elecs. Co., 2020 U.S. App. LEXIS 5269 (Fed. Cir. Feb. 21, 2020)

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