General distinctions drawn between the claimed invention and the prior art are not sufficient to provide any objective boundaries for terms of degree. Here, for example, the patentee’s argument during prosecution that prior art disk-shaped and plate-shaped heat sinks were not “elongated” as claimed was found to create an unresolved ambiguity as to how the prior art elements are not considered to be “elongated.” “Those general descriptions hardly provide the necessary ‘objective boundaries’ about the length or shape of an ‘elongated’ core.” It may therefore be helpful to provide or specifically claim more concrete boundaries for any terms of degree introduced during prosecution that do not have the requisite objective boundaries in the original specification.
Background / Facts: The patent being asserted here is directed to heat sinks for LED lamps. The asserted claims all require a thermally conductive and “elongated” core to dissipate heat from the LEDs. However, the term “elongated” appears nowhere in the specification, nor are the core’s dimensions otherwise described in text or drawings. In the prosecution history, the patentee distinguished a disk-shaped heat sink and a plate-shaped heat sink in the prior art as not containing an “elongated” element, even though the disk and plate both extend in length.
Issue(s): Whether the asserted claims are indefinite because a person of ordinary skill in the art would have no objective means to determine which cores are “elongated” and which are not.
Holding(s): Yes. “Although ‘a patentee need not define his invention with mathematical precision’ [], at best, a skilled artisan would know from the prosecution history only that the elongated cores cannot be ‘disk or plate shaped’ or ‘generally planar.’ [] Those general descriptions hardly provide the necessary ‘objective boundaries’ about the length or shape of an ‘elongated’ core.”