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The Intellectual Property Court’s Opinion on Whether a Claim with a Numerical Limit Is a Selection Invention
A "selection invention" is an invention that is based on the selection of subordinate elements of the superordinate concept underlying a known invention. According to Section 3.5 of the current Patent Examination Guidelines, the standard for determining the inventive step of a selection invention is strict, which requires the determination of whether the selected part produces any unexpected results over the prior art in order to determine whether the claimed invention could be easily arrived at.
In its 2017 Xing Zhuan Su Zi No. 71 Administrative Judgment, the Intellectual Property Court has clearly explained whether the invention of a claim with a numerical limit is a selection invention. The invention of the patent involved in that case is a "writing instrument with a friction body." Claim 1 of that patent recites, among others, that "the contact area (A) is in the range from 3.0 to 13.0 mm2 when pressed against a glass plate with a load of 1,000 grams," that "the contact area (B) is in the range from 1.4 to 3.2 mm2 when pressed against a glass plate with a load of 500 grams," and that "A and B satisfy the equation of B<A≦4B." After the intervening party filed an cancellation petition, the Intellectual Property Office determined that the petition should be granted and the patent was therefore revoked. During the administrative litigation, the intervening party argued that the limit of the contact area equation in Claim 1 of the patent rendered the claimed invention a selection invention and that because the plaintiff (i.e., the patentee) did not prove that such limit values were features that would produce unexpected results over the prior art, the claimed invention should be deemed to lack an inventive step.
In this regard, the Intellectual Property Court has stated the following: "A selection invention is an invention that involves the selection of individual elements, subsets or sub-ranges, which have not been explicitly mentioned, within a larger known set or range. For the disputed patent, Features 1 and 2 (i.e., the contact areas under the load of 1,000 grams and 500 grams) and Feature 3 (i.e., the elastomer equation satisfying B<A≦4B) are technical features not covered by the prior art of Exhibits 2, 3 and 10. Therefore, the patent is not an invention that purposefully selects individual elements, subsets or sub-ranges, which have not been explicitly mentioned, within a larger known set or range. The purpose of the disputed patent is to use reversible thermochromic ink to freely form an image with the handwriting width in the range from 0.1 to 1 while the contact area of which reflects different pressure conditions of 500 grams and 1,000 grams. The glass plate's pressurized contact area under the minimum handwriting width has been clearly defined. Therefore, the invention is not created by the above-mentioned 'purposeful selection of individual elements, subsets or sub-ranges, which have not been explicitly mentioned, within a larger known set or range,' and thus the disputed patent is not a selection invention."
The Intellectual Property Court has further stated the following: "The embodiments provided in the specification of the disputed patent have revealed different contact areas and handwriting widths, which shows that the micro area could be easily discolored by friction without increasing the times of friction or strong pressing force. Therefore, the technical features of the corresponding contact area range under the different pressurized load of 500 grams and 1,000 grams in Claim 1 of the disputed patent are not features that could be easily arrived at by a person skilled in the art through carrying out repeated friction tests with a narrow handwriting width. It is not a prior art without a numerical limit on selected area and thus not a type of selection invention. The intervening party's presumption that the claimed invention is a selection invention should not be accepted."
Therefore, the invention of a claim with a numerical limit is not necessarily a selection invention, and this issue should be determined based on whether the invention requires a "purposeful selection of an individual component, subgroup or sub-range, which has not been explicitly mentioned, within a larger known set or range."